a study of a self generated stratospheric sudden warming and its mesospheric lower thermospheric impacts using the coupled time gcm ccm3 1 a stratospheric sudden warming episode was self consistently generated in the coupled national center for atmospheric research thermosphere ionosphere mesosphere and electrodynamics general circulation model climate community model version 3 time gcm ccm3 taking advantage of the unique vertical range of the coupled model ground to 500 km we were able to study the coupling of the lower and upper atmosphere in this warming episode planetary wave 1 is the dominant wave component in this warming event analysis of the wave phase structure and the wave amplitude indicates that the wave may experience resonant amplification prior to the peak warming the mean wind in the high latitude winter stratopause and mesosphere decelerates and reverses to westward due to planetary wave forcing and forms a critical layer near the zero wind lines the wind deceleration and reversal also change the filtering of gravity waves by allowing more eastward gravity waves to propagate into the mesosphere and lower thermosphere mlt which causes eastward forcing and reverses the westward jet in the mlt this also changes the meridional circulation in the upper mesosphere from poleward downward to equatorward upward causing a depletion of the peak atomic oxygen layer at 97 km and significant reduction of green line airglow emission at high latitudes and midlatitudes planetary waves forced in situ by filtered gravity waves in the mlt grow in the warming episode their growth and interaction with tides create diurnal and semidiurnal variabilities in the zonal mean zonal wind

solar and lunar tidal variabilities in gps tec and geomagnetic field variations seasonal as well as during the sudden stratospheric warming of 2010 the global positioning system gps deduced total electron content tec data at 15 n geomagnetic which is the northern crest region of equatorial ionization anomaly are used to study solar and lunar tidal variabilities during the years 2008 and 2009 and also during the 2009 2010 winter when a major sudden stratospheric warming ssw event has occurred the diurnal and semidiurnal tidal amplitudes show semiannual variation with maximum amplitudes during february march and september november whereas terdiurnal tide is larger during april september they show significant longitudinal variability with larger smaller amplitudes over 250 e 150 e 200 e 250 e lunar semidiurnal tidal amplitudes show sporadic enhancements during northern winter months and negligible amplitudes during northern summer months they also show notable longitudinal variabilities the solar migrating tides dw1 and sw2 show semiannual variation with larger amplitudes during spring equinox months whereas tw3 maximizes during northern summer dw2 shows larger amplitudes during summer months during the ssw except tw3 the migrating tides dw1 and sw2 show considerable enhancements among solar nonmigrating tides sw1 tw2 and ds0 show larger enhancements solar tides in tec and equatorial electrojet strength over tirunelveli vary with the time scale of 60 days during october 2009 march 2010 similar to ozone mass mixing ratio at 10 hpa and this confirms the vital role of ozone in tidal variabilities in ionospheric parameters lunar tidal amplitudes in changes in horizontal component of geomagnetic field h are larger over tirunelveli a station near dip equator solar semidiurnal tides in h have larger amplitudes than lunar tides over polar stations mawson and godhavn

a measurement of lunar tides in the mesosphere at adelaide south australia wind measurements at adelaide 35 s at heights from 76 to 98 km are analyzed for semidiurnal or semimonthly lunar tides two data sets are used one of about 2 years 1984 1985 and one of 1 year 1986 the lunar tide amplitude generally has its largest values at the equinoxes though this pattern changes in 1984 1985 at the greatest heights to solstice maxima especially in winter july diurnal average amplitudes reach 4 m s 1 while the largest value obtained was 8 m s 1 inferred vertical wavelengths of the propagating tides were rather variable and there was evidence of possible mode coupling and interference in summer wavelengths of 25 km occurred below 92 km and were evanescent above while in winter long wavelengths were found in the 78 to 90 km range with shorter 38 km wavelengths above that height comparisons of phases with results from saskatoon and kyoto suggest that around 95 km antisymmetric modes may be dominant in june and december and symmetric modes in february diurnal variations in the lunar tide were evident and year to year changes were seen in some aspects comparison with currently available models shows several points of disagreement

chemographic relationships of biotite and cordierite in the mcgerrigle thermal aureole gaspe quebec biotite and cordierite occur in a 1 km wide zone of pelitic hornfelses around the mcgerrigle pluton these phases display systematic changes in xfe that can be attributed to continuous reactions involving chlorite or andalusite in the system kfmash through much of the zone biotite and cordierite were products of the breakdown of chlorite close to the pluton this continuous reaction was terminated by a discontinuous reaction that introduced andalusite pelites which interdigitate with apophyses of the intrusive at the pluton margin contain assemblages that record a continuous reaction between biotite cordierite andalusite muscovite and quartz or alternatively the discontinuous breakdown of muscovite and quartz to k feldspar and andalusite the mole fraction of fe in biotite and cordierite increased significantly with the progress of the first continuous reaction and apparently decreased during the second continuous reaction the kd of fe mg between the minerals decreased and apparently increased respectively during the two reactions biotite cordierite chlorite assemblages are interpreted to have been stable at temperatures between 525 c and 615 c and biotite cordierite andalusite assemblages stable at temperatures between 615 c and 635 c the confining pressure was estimated to have been 2 kbar the results of this study suggest that the kd of fe mg between biotite and cordierite is a function of temperature the fe mg exchange characteristics of the controlling continuous reaction and non ideal mixing of fe and mg

assessment of crystallographic orientation effects on secondary ion mass spectrometry sims analysis of cassiterite abstract crystallographic orientation effects on ion microprobe analyses for u pb and o isotopes have been reported for a number of oxide minerals including rutile tio2 and baddeleyite zro2 here we evaluate the effects of crystal orientation on u pb and o isotopic data measured by ion microprobe on cassiterite sno2 which is isostructural with rutile the crystallographic orientations of mounted and polished grains of cassiterite were determined by electron backscatter diffraction ebsd those grains were then analysed for u th pb isotopes and 18o 16o compositions using the shrimp rg and shrimp si ion microprobes respectively based on these data cassiterite appears to show no dependence of key measurement parameters such as uo2 uo pb uo or 18o 16o ratios at the achieved precision with crystallographic orientation the contrasting behaviour of isostructural cassiterite and rutile provides new insights into the mechanisms leading to crystallographic orientation effects during ion microprobe analyses with electronic structure proposed as being a significant factor

planetary waves and variability of the semidiurnal tide in the mesosphere and lower thermosphere over esrange 68 n 21 e during winter 1 the main features of the planetary waves and the variability of the semidiurnal tide with planetary wave periods observed by meteor radar over esrange 68 n 21 e have been investigated the interval of 39 months covering continuous measurements from october 1999 to december 2002 has been examined the planetary waves most frequently observed by meteor radar measurements in the mesosphere and lower thermosphere 80 100 km over esrange are 5 8 to 10 16 and 23 day waves the quasi 2 day wave is excluded in this study they are strongly amplified in the winter some differences between high and middle latitude planetary waves notwithstanding the 5 10 and 16 day waves are most probably related to the well known normal mode there are some reasons to believe that the vertically upward propagating 23 day wave could be generated by solar forcing the variability of the semidiurnal tide with periods of planetary waves has been thoroughly studied as well it is found that in the winter when the planetary waves are significantly amplified a very strong periodic variability of the semidiurnal tide is observed as well this result indicates that the most probable mechanism responsible for the periodic tidal variability during winter is in situ nonlinear coupling between tides and planetary waves two winter periods have been examined 1999 2000 and 2001 2002 in order to find strong evidence supporting this suggestion the validity of the frequency phase and vertical wavenumber wavelength relationship between the prime the planetary wave and semidiurnal tide and secondary waves has been established the novel aspect of this work is that we show for the first time that the calculated vertical structures vertical wavelengths of the sum and difference secondary waves which have very close periods are actually very different

equatorial vertical drift modulation by the lunar and solar semidiurnal tides during the 2013 sudden stratospheric warming during the 2013 stratospheric sudden warming ssw period the jicamarca unattended long term investigations of the ionosphere and atmosphere julia radar at jicarmarca peru observed low latitude vertical drift modulation with lows of 0 12 m s daytime maximum drifts between 6 13 and 22 25 january and enhanced drifts up to 43 m s between 15 snd 19 january the ncar thermosphere ionosphere mesosphere electrodynamics general circulation model reproduces the prevailing vertical drift feature and is used to examine possible causes the simulations indicate that the modulation of the vertical drift is generated by the beating of the semidiurnal solar sw2 and lunar m2 tides during the ssw period the beating is observable since the magnitudes of lunar and solar semidiurnal tidal amplitudes are comparable the theoretical beating frequency between sw2 and m2 is 1 15 13 day which may be modified due to phase changes this study highlights the importance of the lunar tide during ssw periods and indicates that the equatorial vertical drift modulation should be observable at other longitudes as well

on the relationship between weakening of the northern polar vortex and the lunar tidal amplification in the equatorial electrojet enhanced lunar tidal effects in the equatorial electrojet eej during northern winters in the form of big l days have been known for a long time recent studies suggest that the changes in the tidal propagation conditions due to stratospheric sudden warmings ssw could be responsible for this phenomenon in this work we have used the h component of the magnetic field recorded at huancayo from 1997 2013 to study the relation between the timing and magnitude of the semi monthly lunar tide in the eej and the stratospheric polar vortex weakening pvw we prefer a definition of pvw by taking into account the atmospheric conditions from december to february for each winter our results indicate that the semi monthly lunar tide in the eej gets enhanced during northern winters when a significant pvw occurs and its peak timing and magnitude is correlated with the timing and intensity of pvw the timing of lunar tidal peaks and pvw correlate better than their respective magnitudes our results suggest that the initiation of the lunar tidal enhancement in most of the cases is closely related to a pvw event furthermore we discuss events where the semi monthly lunar tidal enhancements are not well timed with respect to pvw we also suggest that the amount of tropospheric forcing into the stratosphere plays a major role in the enhancement of the lunar tides in the eej

excavation damaged zone depths prediction for tbm excavated roadways in deep collieries the excavation works at underground mines create excavation damage zone edz in surrounding rocks around roadway geometry the edz depth is a critical parameter for stability analysis risk assessment support design and toxic waste leakage this paper proposed an innovative edz depth prediction based on a modified nonlinear mohr failure criterion and modification of conventional analytical solution by means of perturbation method a set of cyclic loading tests of surrounding rock of roadways are conducted and a modified mohr failure criterion of rocks under cyclic loading path of tbm excavation is established on the basis of test results moreover perturbation method was introduced for enhancing calculation accuracy in order to verify the proposed analytical solution a set of in situ digital panoramic borehole camera image monitoring was carried out within the roadways and the monitoring results correlated well with the proposed analytical solution the edz geometries of roadways in deep mines are typically oval and the edz depth is influenced by ground stress magnitude lateral coefficient and support stress significantly through the proposed analytical solution a more accurate prediction of edz depth of roadways can be obtained conveniently before the excavation works

fracture cleat analysis of coals from zonguldak basin northwestern turkey relative to the potential of coalbed methane production abstract in this study the fracture structure of three coals sulu k 1 acilik k 2 and cay dogu ayak from two different seams in the zonguldak basin located on the black sea coast of turkey have been analyzed in relation to coalbed methane recovery x ray computerized tomography ct light microscopy image analysis and scanning electron microscopy sem analysis have been performed on mine coal samples to have a better understanding of distribution of minerals fracture morphology and apertures and matrix fracture interactions via examination of fracture surfaces results show that the acilik and sulu coals seem to be structurally more prone to be commercially productive these coals show a high degree of fracturing and cleat development as evidenced by x ray ct and light microscopy examination of polished surfaces although the cay dogu ayak coal shows a high fracture density the cleat surface morphology and smaller fracture apertures may make this coal unfavorable for gas flow

metallogenesis and geodynamics of the lachlan orogen new and old insights from spatial and temporal variations in lead isotopes abstract analysis of the distribution patterns of pb isotope data from mineralised samples using the plumbotectonic model of carr et al 1995 which invokes mixing between crustal and mantle reservoirs indicates systematic spatial patterns that reflect major metallogenic and tectonic boundaries in the paleozoic lachlan and delamerian orogens in new south wales and victoria australia this distribution pattern accurately maps the boundary between the central and eastern lachlan subprovinces the central lachlan subprovince is characterised by pb isotope characteristics with a strong crustal signature whereas the eastern lachlan subprovince is characterised by variable crustal and mantle signatures the macquarie volcanic province is dominated by pb with a mantle signature known porphyry cu au and high sulphidation epithermal au cu deposits in the province are associated with a zone characterised by the strongest mantle signatures in contrast granite related sn deposits in the central lachlan subprovince are characterised by the strongest crustal signatures the pb isotope patterns are broadly similar to nd isotope model age patterns derived from felsic magmatic rocks although a lower density of nd isotope data locations makes direct comparison difficult the two reservoirs identified by carr et al 1995 do not appear to be isotopically linked the crustal source was not formed via extraction from the mantle source rather the two reservoirs formed separately the mantle reservoir may have been sourced from a subducting proto pacific plate whereas the crustal reservoir is most likely to be extended australian crust the data allow the possibility that the proto pacific mantle source was isotopically linked to the western tasmanian crustal source comparison of pb isotope data from the girilambone district central lachlan subprovince e g tritton and avoca tank cu deposits with those from the cobar cu au zn pb district eastern lachlan subprovince in north central new south wales indicates a less radiogenic signature and probably older age for deposits in the girilambone district hence a syngenetic volcanic associated massive sulphide origin for these deposits is preferred over a syn tectonic origin the data are also consistent with formation of the girilambone deposits in a back arc basin inboard from the earliest phase of the macquarie volcanic province

investigation of the excavation damaged zone around deep tbm tunnel using a voronoi element based explicit numerical manifold method abstract a voronoi element based explicit numerical manifold method is adopted to investigate the evolution process and failure characteristics of the excavation damaged zone around a deeply buried tbm tunnel an explicit time integration scheme of numerical manifold method is adopted as the numerical platform based on which a voronoi polygon assemblage is generated to approximate the blocky structure of the surrounding rock mass resulting from discrete fracture networks a new mathematical mesh generation method is developed to better adapt to the voronoi polygons and an excavation algorithm including both in situ stress equilibrium and tbm excavation modelling techniques is proposed to capture the mechanical response of the tbm tunnelling process with the newly developed ve enmm approach the progressive failure process of the surrounding rock mass in a headrace tunnel of yindajihuang project is simulated and the formation mechanism of the excavation damaged zone is explored simulation results show that a large extent of excavation damaged zone is easily formed in the highly fractured rock mass due to the high in situ stress in deep grounds besides relatively large convergence displacements are predicted around the tunnel surface leading to a high risk of tbm shield jamming as in the practical situation however the development of damaged zone is effectively restrained and the convergence displacements are well controlled by an early installation of the tunnel lining segments thus preventing the occurance of tbm shield jamming additional simulations are conducted to study the effects of the lateral in situ stress ratio on the excavation damaged zone it is inferred that the increase of lateral stress ratio facilitates the fracturing of the surrounding rock mass which results in a larger extent of the damaged zone and more severe squeezing deformation compared with those under lower lateral stresses

a global view of the atmospheric lunar semidiurnal tide 1 atmospheric lunar semidiurnal tides are studied using 10 years of temperature data collected by the thermosphere ionosphere mesosphere energetics and dynamics sounding of the atmosphere using broadband emission radiometry satellite the amplitudes and phases in the temperature field are calculated by performing least mean square fit in a data set of about 60 day interval combining ascending and descending data together the mean tidal structures are studied for the height range from 20 to 120 km between 50 latitude and centered on each month from february 2002 to january 2012 a clear signature of the 12 42 h lunar semidiurnal tide is observed in the data characteristic of propagating waves is observed in the vertical amplitude and phase profiles in almost all heights the best conditions of propagation for the lunar semidiurnal tide are reached in the lower thermosphere region asymmetry between the hemispheres and seasonal variability is observed in the amplitudes of the tide longitudinal variations are also observed which reveals the existence of nonmigrating components in addition to the dominant migrating lunar tide

deformation characteristics of a roadway in steeply inclined formations and its improved support abstract mining roadways in steeply inclined rock layers commonly experience severe deformation in form of large asymmetric deformation roof subsidence and floor heave which significantly threaten the stability of a roadway using a coal exploration roadway in anhui province china as a case study the deformation characteristics of a roadway in steeply inclined rock formations and the corresponding improved support scheme is analysed by numerical simulation the simulation is performed using a cohesive element to consider the influence of geologic bedding plane around the roadway the results show that due to the spatial relationship of the roadway and the two bedding planes i e interfaces rocks above the roadway move downward along the interface while rocks below the roadway move upward along the interface the maximum deformation occurs along the upper left and lower right sides of the roadway surface which accounts for the large leaning asymmetric deformation of the roadway right inclination an improved support scheme for the roadway is proposed using long cables to restrain severe deformation short cables and enclosed u shaped steel sets to improve the ground stress state the proposed scheme can effectively restrain floor heave manage large asymmetrical deformation compared to the original scheme

numerical modelling of the effects of weak immediate roof lithology on coal mine roadway stability abstract the stability and associated design of roof reinforcement requirements of tunnels driven in united kingdom coal measures strata is directly related to the engineering characteristics of the immediate roof lithology and the effects of redistribution of the in situ stress numerical modelling carried out by the authors has been used to simulate the widely observed detrimental effects of both high horizontal stress and weak immediate roof lithology on tunnel roof stability different numerical modelling techniques such as continuum discontinuum and hybrid finite element discrete element codes have been used to model the deformational behaviour of coal measures strata and are discussed in the context of specific case examples to highlight their application and suitability for modelling of weak rock the modelled results demonstrate that the thickness of the relatively weak mudstone in the roof of the tunnel has a significant influence on the extent of failure and ultimately the need for additional reinforcement

investigation of key techniques on floor roadway support under the impacts of superimposed mining theoretical analysis and field study various sizes of coal pillars will be formed after the mining of close distance coal seams the concentrated stress formed on the coal pillars can cause serious deformation and failure to the roadway below floor roadway wantian coal mine in guizhou was taken as an example to study the stress propagation and distribution of roadway by kirsch equations based on the stope condition a numerical model was established to analyze the changes of stress displacement and plastic zones around roadways and the cause for roadway deformation during the mining of the upper coal seams the new support scheme was designed and applied at the study site the results show that the vertical stress the maximum shear stress and the plastic zones of the rock surrounding the roadway increase with the mining of the upper working faces roadway deformation and failure mainly occurs at floor sides and corners the key of roadway support was to control floor heave and then to recover the integrity and strength of the surrounding rock of two sides the developed omnidirectional rotatable drilling equipment can guarantee the success rate of floor drilling the broken surrounding rock of floor was enhanced through grouting the high prestress cable was used to support the roof and two sides and the birdcage cable was for the floor by the new support system the roadway deformation was controlled which could meet the support requirements

effect of rock mass and discontinuity mechanical properties and delayed rock supporting on tunnel stability in an underground mine abstract in this paper the rock mass stability around the tunnels in an underground mine is investigated using the distinct element method a three dimensional model was developed based on the available geological geotechnical and mine construction information it incorporates the inclined lithologies including a weak interlayer the persistent and non persistent faults and a complex tunnel system the strain softening constitutive model was prescribed for the rock masses in the numerical model the continuously yielding joint model was used to describe the non linear behavior of the faults to account for the deformations occurred between the excavations and rock supporting the delayed installation of supports was implemented by using the stress relaxation method numerical analyses were performed to study the effects of the post failure constitutive parameters of the rock masses the mechanical properties of faults and the delayed supporting on tunnel stability the following results are presented a the rock mass deformations and failure zones around the excavations b the joint shear displacements of the major fault and c the failure conditions of the applied supports satisfactory comparisons are obtained between the predictions based on numerical modeling and the field deformation measurements the analysis procedures presented in this study are applicable for stability assessment of various underground rock excavation projects located in different parts of the world having different geological settings and complex engineering situations

monitoring of coal mining subsidence in peri urban area of zonguldak city nw turkey with persistent scatterer interferometry using alos palsar this paper presents the results of spatiotemporal monitoring of surface subsidence over a mining area in zonguldak province of turkey using synthetic aperture radar sar data providing maps of subsidence rates in the radar line of sight direction a total of 18 sar images acquired between january 2007 and june 2010 by the japanese advanced land observing satellite have been used to map the surface displacements using the persistent scatterer interferometry technique the use of phased array type l band synthetic aperture radar data has proved useful for avoiding signal decorrelation and estimating surface deformation in the heavily vegetated study region the technique enables the monitoring of continuous small displacements over a large area our findings present that many persistent scatterers were located on the vegetation cover the results reveal areas of ground surface subsidence up to 44 mm year that are well correlated with the underground coal mining galleries particularly in the gelik region where the karadon mining galleries are present

longitudinal variation of the lunar tide in the equatorial electrojet the atmospheric lunar tide is one known source of ionospheric variability the subject received renewed attention as recent studies found a link between stratospheric sudden warmings and amplified lunar tidal perturbations in the equatorial ionosphere there is increasing evidence from ground observations that the lunar tidal influence on the ionosphere depends on longitude we use magnetic field measurements from the champ satellite during july 2000 september 2010 and from the two swarm satellites during november 2013 february 2017 to determine for the first time the complete seasonal longitudinal climatology of the semidiurnal lunar tidal variation in the equatorial electrojet intensity significant longitudinal variability is found in the amplitude of the lunar tidal variation while the longitudinal variability in the phase is small the amplitude peaks in the peruvian sector 285 e during the northern hemisphere winter and equinoxes and in the brazilian sector 325 e during the northern hemisphere summer there are also local amplitude maxima at 55 e and 120 e the longitudinal variation is partly due to the modulation of ionospheric conductivities by the inhomogeneous geomagnetic field another possible cause of the longitudinal variability is neutral wind forcing by nonmigrating lunar tides a tidal spectrum analysis of the semidiurnal lunar tidal variation in the equatorial electrojet reveals the dominance of the westward propagating mode with zonal wavenumber 2 sw2 with secondary contributions by westward propagating modes with zonal wavenumber 3 sw3 and 4 sw4 eastward propagating waves are largely absent from the tidal spectrum further study will be required for the relative importance of ionopsheric conductivities and nonmigrating lunar tides

depth of emplacement fluid provenance and metallogeny in granitic terranes a comparison of western thailand with other tin belts the most important tin mineralization in thailand is associated with the late cretaceous to middle tertiary western thai granite belt a variety of deposit types are present in particular pegmatite vein and greisen styles of mineralization a feature common to most of the deposits is that they are associated with granites that were emplaced into the khang krachan group which consists of poorly sorted carbonaceous pelitic metasediments most of the deposits contain low to moderately saline aqueous fluid inclusions and aqueous carbonic inclusions with variable ch4 co2 ratios low salinity aqueous inclusions represent trapped magmatic fluid in at least one case the nong sua pegmatite based on their occurrence as primary inclusions in magmatic garnet aqueous carbonic inclusions are commonly secondary and neither the co2 nor nacl contents of these inclusions decrease in progressively younger inclusions implying that they are not magmatic in origin reduced carbon is depleted in the metasediments adjacent to granites and the d values greisen muscovites are variable but are as low as 134 per mil indicative of fluid interaction with organic graphitic material this suggests that the aqueous carbonic fluid inclusions represent fluids that were produced at least in part during contact metamorphism metasomatism by comparing the western thai belt with other sn w provinces it is evident that there is a strong correlation between fluid composition and pressure in general low to moderately saline aqueous inclusions and aqueous carbonic inclusions are characteristic of mineralization associated with relatively deep plutonic belts mineralized pegmatites are also typically of deeper plutonic belts and pegmatite hosted deposits may contain cassiterite that is magmatic crystallized from granitic melt or is orthomagmatic hydrothermal crystallized from aqueous or aqueous carbonic fluids in origin the magmatic aqueous fluids those that were exsolved from granitic melts are interpreted to have had low salinities as a consequence of the low salinities tin is partitioned in favour of the melt on vapour saturation thus with a high enough degree of fractionation the crystallization of a magmatic cassiterite or different sn phase such as wodginite is inevitable because tin is not partitioned in favour of the vapour phase upon water saturation of the granitic melts it is proposed that relatively deep vein and greisen systems tend to form by remobilization processes in addition many deeper greisen systems are hosted in part by carbonaceous pelitic metasediments and the reduced nature of the metasediments may play a key role in remobilizing tin sub volcanic systems by contrast are characterized by high temperature high salinity fluids owing to the high chlorinity tin is strongly partitioned in favour of the vapour and cassiterite mineralization can form by of orthomagmatic hydrothermal processes similar relationships between the depth of emplacement and fluid composition also appear to apply to other types of granite hosted deposits such as different types of molybdenum deposits

lunar tide in the thermosphere and weakening of the northern polar vortex the lunar tide and its variability are beginning to be realized as elements of ionosphere thermosphere weather herein we demonstrate that an enhancement in m 2 amplitude at 110 km in the dynamo region is related to the timing and intensity of stratospheric polar vortex weakening pvw timing of the pvw which typically occurs during january february changes on the order of 4 7 d yr between 2002 and 2013 and the m2 enhancement changes with it with a time delay of order 2 8 days the m2 temperature amplitude at 110 km as determined from the sounding of the atmosphere using broadband emission radiometry saber measurements on the thermosphere ionosphere mesosphere energetics dynamics timed spacecraft increases linearly from about 20 k to 29 k as the westward zonal mean zonal wind increases from about 10 m s 1 to 80 ms 1 at 70 n and 48 km altitude in accord with pvw events from year to year according to modern era retrospective analysis for research and applications merra data these relationships point to a level of predictability regarding impacts of the lunar tide on thermosphere and ionosphere densities winds and plasma drifts

investigation on the evolution and control of surrounding rock fracture under different supporting conditions in deep roadway during excavation period abstract this paper presents an investigation of fracture evolution of surrounding rock with different supporting conditions during excavation period in hulusu coal mine inner mongolia china fractures of surrounding rock were measured by borehole images obtained with a digital panoramic borehole camera and surface displacement of roadway was measured using the intersection point method based on the rock properties original support method and constructional process of bolter miner a simple and fast support system was proposed which realized the complete parallel operation between bolt support and coal cutting according to the data obtained from field monitoring and construction situation the array pitch was extended from 1 0 m to 1 5 m gradually field measurements indicated that the overall effect of roadway under new support was more satisfactory than under original support with no exception in all the five test stages when the array pitch extended up to 1 5 m the roof and rib convergence were 11 mm and 16 mm a reduction of 66 7 and 57 9 respectively under new supporting condition fractures were distributed only within the bolt anchorage zone and both the number and opening of fractures were small by contrast under original supporting condition fractures were distributed both in and out of the bolt anchorage zone new support can make full use of deep strata by constructing thick anchorage rock beam and large displacement of shallow strata can be inhibited through small displacement of deep strata the realization of co movement between large small displacements ensures the safety control of roadway new support can greatly improve support efficiency providing a solution to the imbalance between excavation speed and production needs widely existing in coal mines producing 10 million tons a year new support has already been successful applied in another roadway with top coal in hulusu coal mine

the role of the mantle in the genesis of tin deposits and tin provinces of eastern australia initial nd isotope data for the four granites related to the ardlethan sn deposit in the wagga sn belt of the central lachlan fold belt of eastern australia range from 11 6 to 2 1 increasing with increasing fractionation the four granites beneath the renison tin mine in western tasmania range from 6 1 to 3 9 the data clearly establish the presence of light rare earths of mantle origin in the fractionated granites associated with the ardlethan porphyry sn deposits and hint at the same relationship for the renison granites though in this case the mineralizing pluton is probably yet to be discovered sulfur and carbon isotope data from the ardlethan and renison ores and from similar deposits in tasmania suggest that mantle volatiles played a significant role in the genesis of sn granites and deposits mantle input may have occurred either by mixing of crustal and mantle melts or metasomatism by mantle derived fluids

computation of subsidence parameters resulting from layer movements post operations of underground mining abstract it is obvious to anyone working on or dealing with underground mining operations production gaps have to be opened in the ground during mining the ground layers just above these gaps collapse toward production lines resulting in horizontal and vertical movements both inside and on the earth s surface these movements are referred to as mining subsidence which eventually causes technical economic social and environmental hazards to natural and cultural structures on the surface it is substantially crucial to the general and regional characteristics of these subsidence occurrences in the underground mining region so it can be possible to mitigate the subsidence induced damages and problems both in the ground and on the surface subsidence observations thus are conducted inside and on the ground by employing geodetic geophysical and geotechnical methods with the aim to determine the characteristics and parameters of subsidence occurrence in a region evaluating these subsidence observations the zonguldak hard coal basin and kozlu coal production region within the basin are places where urbanization and underground mining operations are intensively under way therefore it is vitally important to continuously monitor the horizontal and vertical displacements formed due to the underground mining in the basin and to determine the subsidence parameters so that it may be possible to forestall the subsidence induced issues that may occur in the near future this study yields information and computations about the subsidence parameters determined under the light of three periods of geodetic observations carried out in the region using the three periods of gps and precise leveling observations the average slope angle values resulting from vertical displacements in the study region were obtained from the adjusted coordinates and height differences and estimated as 16 67 in positive direction and 18 03 in negative direction the horizontal unit deformation parameters on the other hand were computed as 0 28 mm m for the extension parameter while 0 26 mm m for compression parameter along the routes chosen in the kozlu region

deformational behaviour of roadways in soft rocks in underground coal mines and principles for stability control following a brief introduction to the nature of a roadway excavated in soft rocks in underground coal mines six characteristics featuring its deformational behaviour are formulated and illustrated extensively with data collected over decades the characteristics are 1 a high rate of rapid deformation in response to ground pressure redistribution 2 evident rheological deformation 3 high sensitivity to stress changes 4 high sensitivity to water invasion 5 deformation occurring in all directions of the roadway cross section and 6 a predominant floor heave component in the roof to floor convergence in view of the nature of an underground roadway located in soft strata principles for controlling the roadway stability both effectively and economically for the whole service life span are specified a case study is also presented in order to demonstrate the application of the outlined principles for the stability control of roadways excavated in such soft rocks using a multiple support system with joints

geology re os ages sulfur and lead isotopes of the diyanqinamu porphyry mo deposit inner mongolia ne china the diyanqinamu porphyry mo deposit in the southern greater khingan range of the central asian orogenic belt contains 800 million metric tons mt of ore with an average grade of 0 097 molybdenum the deposit is hosted in late jurassic volcanic rocks of tuff andesite and volcanic breccia multiple stage hydrothermal activities have resulted in propylitic phyllic and argillic alteration in this deposit five stages i v of hydrothermal activity are identified stage i is represented by a mineral assemblage of epidote chlorite and magnetite with some discontinuous barren veinlets of quartz k feldspar fluorite magnetite epidote chlorite stage ii is marked by occurrence of quartz fluorite molybdenite magnetite pyrite sericite siderite veinlets veins with phyllic halos stage iii consists of fluorite siderite quartz molybdenite pyrite ankerite calcite chalcopyrite veins that are commonly related to phyllic alteration and dissemination of fluorite in the altered rocks stage iv has an assemblage of fluorite quartz pyrite ankerite calcite molybdenite chalcopyrite sphalerite galena in coarse veins 10 20 mm wide stage v consists of narrow 5 mm wide veinlets of calcite fluorite pyrite quartz molybdenite mainly occurs in stages ii and iii re os dating results for molybdenite samples from these two stages yielded an isochron age of 156 2 4 2 ma 2 mswd 0 96 n 10 most molybdenite samples have high 34s values 8 4 relative to other sulfide minerals i e galena sphalerite pyrite and chalcopyrite of stages ii to v 34s 2 5 8 3 n 22 molybdenite also has low 207pb 204pb and 208pb 204pb ratios relative to other sulfide minerals although there are minor overlaps in a diagram of 206pb 204pb versus 207pb 204pb these pb isotope data display a positive trend transecting the growth curves of crustal lead which could be invoked by mixing of crustal and mantle sources with distinct pb isotopes in combination with the s isotope data and mineral paragenesis we suggest that magmas were the main source of molybdenum whereas other metals i e pb zn and cu were possibly sourced from the country rocks

magmatic and hydrothermal history of the porphyry style deposits of the ardlethan tin field new south wales australia the cassiterite sulfide deposits of the ardlethan tin field are classified as porphyry style sn deposits on the basis of the intimate spatial and temporal relationships of the breccia pipes and sn deposits with the ardlethan granite and in particular the mine porphyry the continuum of salinity and temperature conditions from high temperature and high salinity fluids in the ardlethan granite to lower temperature and less saline fluids in the breccia pipes in the mine granite and the isotopic character of the ore fluids which is consistent with a magmatic fluid source characterized by primitive isotopic signatures for carbon and sulfur the deposits occur in breccia pipes in the siluro devonian mine granite 417 or 2 5 ma close to its contacts with the ardlethan granite 410 or 2 5 ma and ordovician metasediments the ardlethan granite and related phases are moderately to strongly fractionated and enriched in rb th u nb y li as ta w f and sn tourmaline nodules occur within the ardlethan granite and halite bearing fluid inclusions found in quartz from the nodules homogenized between 250 degrees and 485 degrees c one of the most fractionated phases of the ardlethan granite the mine porphyry was emplaced into the major breccia pipe of the mine granite following the onset of brecciation brecciation and mineralization are linked to the release of magmatic volatiles and saline brines from the ardlethan granite the vug filling minerals in all the deposits show a paragenetic sequence from cassiterite wolframite arsenopyrite milky quartz and tourmaline to pyrite chalcopyrite sphalerite galena tourmaline and clear quartz to late stage toothy quartz fluorite and cookeite fluid inclusion data from quartz show that the deposition of milky quartz and cassiterite occurred between 300 degrees and 370 degrees c sulfide and clear quartz between 210 degrees and 2800c and toothy quartz fluorite and cookeite between 105 degrees and 245 degrees c fluid salinities ranged

neodymium and strontium isotope study of the blue tier batholith ne tasmania and its bearing on the origin of tin bearing alkali feldspar granites the middle to late devonian plutons of the blue tier and eddystone batholiths of ne tasmania intrude quartz wacke and mudstone of the ordovician devonian mathinna beds four granitoid types are recognized hornblende biotite granodiorite biotite granite biotite cordierite garnet granite and alkali feldspar granite afg minor diorite bodies and dolerite dykes are also present tin w mineralisation is genetically associated with the afg major granitoid types other than afg of the blue tier and eddystone batholiths all have similar 143nd 144nd initial ratios nd 5 0 to 6 5 at ma more fractionated felsic samples within individual plutons have lower nd values suggesting progressive involvement up to about 5 of the sedimentary country rocks which have nd of about 11 at 370 ma the source rock model age for all granitoids except afg based on a depleted mantle evolution model tdm is about 1 6 ga on the basis of geochemical data 87sr 86sr initial ratios 0 707 0 713 oxygen isotope ratios 180 9 to 12 and rb sr and k ar isotopic age dates 368 to 388 ma the major plutons were interpreted to have been generated independently from heterogeneous crustal sources geochemical variation within each major granitoid type with the possible exception of the afg is due to fractional crystallisation accompanied by some country rock assimilation integrated nd sr and o isotopic systematics of the blue tier batholith of the bassian terrain are different from granite batholiths in the mainland of the lachlan fold belt similarity of isotopic systematics of the blue tier batholith to those of devonian granites in central victoria reinforces the geological correlation between western tasmania and south australia in the early paleozoic two competing hypotheses for the generation of sn w mineralized afg have been proposed on the basis of geological relationships chemical and mineralogical trends and stable and radiogenic isotopes the first hypothesis groves et al 1977 higgins et al 1985 higgins 1990 links the afg with the country rock more mafic poimena granite through processes of fractional crystallisation and subsequent metasomatic modification the second hypothesis suggests that these afg are unrelated to the poimena granite they are specialised granites derived from a different parent with distinctive chemical isotopic systematics sun et al 1986 mackenzie 1986 mackenzie et al 1988 1990 according to the first hypothesis the afg exhibit a range in nd initial values from 5 9 to 2 2 however there is no known isotopic mechanism which can produce this range within the geological time frame of intrusion and solidification at this time the authors favour the second hypothesis because of chemical and isotopic correlations on the basis of a distinct discontinuity between poimena and afg on a y versus ga al plot there is also a clear grouping of initial nd for the poimena granite around 6 and the afg 2 4 it is argued that those few afg having much lower nd than 2 4 are either samples of altered poimena granite two samples with nd 6 8 and 9 1 or a result of extensive metasomatic modification one sample nd 5 9 involving circulation of fluids in equilibrium with the country rocks poimena granite initial nd 6 and mathinna beds 11 hydrothermal minerals from the anchor tin deposit show a range in initial nd and 87sr 86sr correlated with paragenesis apatite formed during albitisation of the lottah granite has nd and sr isotopic compositions intermediate between those of the lottah and poimena granites greisen fluorites have initial nd between 4 0 and 4 6 closer to the lottah average composition while initial 87sr 86sr approaches that of the metasedimentary country rock 0 729 fluorites formed during sericitic alteration have lower nd compositions 0 721 these data support an origin of tin mineralisation through mixing of an afg derived magmatic fluid with a externally derived meteoric groundwater dominated fluid

application of manley rowe relation in analyzing nonlinear interactions between planetary waves and the solar semidiurnal tide during 2009 sudden stratospheric warming event

coal rank and petrography of upper carboniferous seams in the amasra coalfield turkey abstract the amasra coalfield is a part of the upper carboniferous zonguldak coal basin of turkey within the istanbul zone a hercynian deformed unit forming the eastern continuation of the moesian platform in se europe which was later deformed by alpine tectogenesis the mainly westphalian aged coals were sampled from an underground mine and from cores from nine exploration wells and petrographic maceral and microlithotype analysis and mean maximum vitrinite telocollinite reflectance r max in oil were determined the coals were characterised by low ash and low total sulphur contents abundant vitrinite group macerals and relatively abundant vitrite clarite and duroclarite microlithotypes vitrinite reflectance was in the range 0 58 1 04 r max indicating ranks from high volatile c bituminous to high volatile a bituminous coal the r max generally increases with increasing depth in the exploration wells with gradients ranging from 0 21 to 0 40 r max km and an average of 0 30 r max km the highest value occurs in the south of the coalfield in a region of hercynian folding and thrusting the relationship between vitrinite reflectance and thrusts in the wells suggests that coal rank was developed mainly pre thrusting but that some wells arguably show evidence for post thrust coalification peak coalification probably occurred during late mesozoic early tertiary rifting so that the thrusts which developed after coalification are likely to be alpine in age whereas the thrusts that pre date coalification may have been hercynian structures

implications from inclusions in topaz for greisenisation and mineralisation in the hensbarrow topaz granite cornwall england textural and geochemical studies of inclusions in topaz from greisens in the hensbarrow topaz granite stock st austell cornwall are used to constrain the composition of fluids responsible for late stage greisening and mineralisation the topaz contains an abundant and varied suite of inclusions including aqueous liquid vapour l v quartz zinnwaldite albite k feldspar muscovite ilmenorutile apatite columbite zircon varlamoffite sn fe o oh 2 and qitianlingite fe 2 mn 2 2 nb ta 2w 6o10 primary l v inclusions in topaz show relatively high th mainly 300 to 500 c and a narrow range of salinities 23 30 wt nacl equivalent compared with those in greisen quartz 150 450 c 0 50 wt nacl equivalent textures indicate that topaz formed earlier than quartz and the fluid inclusion data are interpreted as indicating a cooling of the hydrothermal fluids during greisenisation mixing with meteoric waters and a decrease in pressure causing intermittent boiling the presence of early formed albite and k feldspar as inclusions in the topaz is likely to indicate that the greisen forming fluid became progressively more acid during greisenisation the most distinctive inclusions in the topaz are wisp and bleb shaped quartz 50 m in size which show textural characteristics indicating former high degrees of plasticity they often have multiple shrinkage bubbles at their margins rich in sn fe mn s and cl and more rarely contain euhedral albite k feldspar stannite or pyrrhotite crystals up to 40 m in size the quartz inclusions show similar morphologies to inclusions in topaz from quartz topaz rocks elsewhere which have been interpreted as trapped silicate melt their compositions are however very different to those expected for late stage topaz normative granitic melts from their textural and chemical characteristics they are interpreted as representing crystallised silica colloid probably trapped as a hydro gel during greisenisation there is also evidence for the colloidal origin of inclusions of varlamoffite in the topaz these occurrences offer the first reported evidence in natural systems for the formation of colloids in high temperature hydrothermal fluids their high ore carrying potential is suggested by the presence of varlamoffite and the occurrence of stannite pyrrhotite and sncl within the quartz inclusions

a diurnal modulation of the lunar tide in the upper atmosphere analysis of geomagnetic data from several stations in the equatorial region shows that the amplitude of the lunar semimonthly tide frequently does not have the expected symmetry about noon in its diurnal variation there is a distinct tendency for larger amplitudes in the morning at many stations this effect is largest in equinoctial months though there are regional differences analysis of data from different years confirms its presence the interaction between solar and lunar tides in the middle atmosphere may be responsible for the observed modulation

metallogenic relationships to tectonic evolution the lachlan orogen australia abstract placing ore formation within the overall tectonic framework of an evolving orogenic system provides important constraints for the development of plate tectonic models distinct metallogenic associations across the palaeozoic lachlan orogen in se australia are interpreted to be the manifestation of interactions between several microplates and three accretionary complexes in an oceanic back arc setting in the ordovician significant orogenic gold deposits formed within a developing accretionary wedge along the pacific margin of gondwana at the same time major porphyry cu au systems formed in an oceanic island arc outboard of an evolved magmatic arc that in turn gave rise to granite related sn w deposits in the early silurian during the ongoing evolution of the orogen in the late silurian to early devonian sediment hosted cu au and pb zn deposits formed in short lived intra arc basins whereas a developing fore arc system provided the conditions for the formation of several volcanogenic massive sulphide deposits inversion of these basins and accretion to the australian continental margin triggered another pulse of orogenic gold mineralisation during the final consolidation of the orogenic belt in the middle to late devonian

the control of coal bed decollement related slickensides on roof falls in north american late paleozoic coal basins abstract slickensides cause potentially hazardous ground conditions in underground coal mines investigations by the mine safety and health administration s msha roof control division indicate that many slickensides represent bedding plane faults and drag folds that formed during coal bed decollement a style of bedding plane faulting that occurs in shale units above coal seams these slickensides formed in response to regional tectonic stresses rather than by differential compaction and strike parallel to local and regional fold axes and thrust faults this paper relates some slickensides in the appalachian illinois arkoma and black warrior basins to the structural grain developed during the late pennsylvanian permian alleghanian orogeny provides descriptions of slickensides and advocates geologic mapping as a predictive method for identifying adverse ground conditions associated with tectonically formed slickensides

origin of the atypical puy les vignes w breccia pipe massif central france constrained by trace element and boron isotopic composition of tourmaline abstract the puy les vignes w deposit is an atypical wolframite bearing hydrothermal breccia pipe hosted in migmatitic biotite sillimanite gneisses in the northwestern french massif central the deposit is characterized by volumetrically important tourmaline alteration allowing to investigate the fluid evolution of the ore forming hydrothermal system four generations of hydrothermal tourmaline tur 1 tur 4 formed during pre syn and post mineralization stages were identified based on detailed petrographic observations and were analyzed in situ for their chemical and boron isotopic compositions at the grain scale tourmaline commonly shows oscillatory zoning and dissolution textures resulting from a multi stage crystallization in a fluid dominated system the different generations of hydrothermal tourmaline have dravite schorl compositions and show similar major and trace element contents falling into the field of metamorphic rocks high concentrations of v cr sr and low concentrations of li sn in tourmaline suggest a metamorphic dominated origin of these elements the boron isotopic compositions of tourmaline range between 13 3 and 7 8 and cannot unambiguously distinguish between a magmatic and a metamorphic fluid origin our data indicate that the chemical and boron isotopic composition of tourmaline was dominantly controlled by high temperature fluid rock interactions between the metamorphic basement and boron rich reduced and low salinity hydrothermal fluids based on these results we propose a fluid evolution scenario for the puy les vignes ore forming hydrothermal system release of magmatic hydrothermal fluids from an unexposed peraluminous leucogranite at ca 324 ma is proposed as the main mechanism responsible for early greisenization and formation of disseminated tur 1 this episode was followed by massive tourmalinization and hydraulic brecciation of the overlying gneisses producing a tourmaline rich tur 2 crackle breccia by interactions with boron rich hydrothermal fluids fluid assisted reopening and collapse of the former tourmalinite at ca 318 ma yielded a matrix supported quartz tourmaline breccia pipe and formation of wolframite bearing quartz veins accompanied by deposition of tur 3 finally post ore hydraulic fracturing at ca 300 ma led to formation of tourmaline rich microbreccias tur 4 possibly from metamorphic fluids

melt inclusions in quartz from an evolved peraluminous pegmatite geochemical evidence for strong tin enrichment in fluorine rich and phosphorus rich residual liquids abstract we have investigated the magmatic evolution of a late stage f and p rich pegmatite forming aluminosilicate liquid and the geochemical controls on magmatic mineralizing processes by remelting totally crystallized melt inclusions in quartz and analyzing the quenched glass by epma and sims the quartz phenocrysts were sampled from a pegmatite that occurs in a variscan granite genetically associated with cassiterite and wolframite mineralized greisen veins at the ehrenfriedersdorf sn w deposit central erzgebirge se germany the melt inclusion compositions imply that the pegmatite forming liquid achieved extreme levels of chemical differentiation it contained high abundances of sn f p li rb cs nb ta and be and abnormally low concentrations of ca y sr and ree for a granite and it was strongly peraluminous the molar al 2 o 3 cao na 2 o k 2 o ranged from 1 3 to 2 0 fractions of the pegmatite forming liquid were extremely enriched in p 2 o 5 f al 2 o 3 and the molar abundances of f p in the glasses correlate strongly with moles of network modifying al ions implying that the bulk liquid included f p and al bearing complexes formation of these complexes reduced the activities of f p and al in bulk liquid suppressed the crystallization of magmatic topaz and p rich minerals and allowed the liquid to become enriched in these constituents some fractions of the ehrenfriedersdorf aluminosilicate liquid contained 1000 2000 ppm sn these levels of sn enrichment were up to 2 orders of magnitude greater than that ever reported for nonmineralized metaluminous and peraluminous igneous materials and are consistent with some experimentally derived sn solubilities in cassiterite saturated granitic liquids at geologically relevant pressures and temperatures this concordance implies that cassiterite could have crystallized directly from this highly evolved p and f rich peraluminous granitic liquid without the involvement of hydrothermal fluids

climatology of semidiurnal lunar and solar tides at middle and high latitudes interhemispheric comparison the semidiurnal lunar and solar tides obtained from meteor radar measurements spanning from 2009 until 2013 observed at davis 69 s and rio grande 54 s are presented and compared to the northern hemisphere ones at andenes 69 n and juliusruh 54 n mean tidal differences for both intra and inter hemispheric scenarios are analyzed tidal behavior is also compared against numerical simulations during 2009 and 2013 sudden stratospheric warming ssw time periods possible influences in the southern hemisphere from the local stratosphere are also investigated using modern era retrospective analysis for research and applications version 2 merra 2 datasets the main features of the mean zonal wind are similar in both hemispheres i e stronger amplitudes over mid latitude locations eastward winds during winter and westward below 90 km with eastwards higher up during corresponding summer times on the other hand the semidiurnal solar tides observed in the southern hemisphere show clear differences when compared to the northern hemisphere and between mid and high latitude locations at the same hemisphere these differences are even larger for the semidiurnal lunar tide which shows stronger amplitudes from october to march and march to october over davis and rio grande respectively our results indicate that the lunar tides over the southern hemisphere mid latitudes are more prone to react to the northern hemisphere stratospheric polar vortex influences in agreement with numerical simulations particularly for the time of the 2013 ssw

september 2019 antarctic sudden stratospheric warming quasi 6 day wave burst and ionospheric effects an exceptionally strong stationary planetary wave with zonal wavenumber 1 led to a sudden stratospheric warming ssw in the southern hemisphere in september 2019 ionospheric data from esa s swarm

modelling of gas generation in coals of the zonguldak basin northwestern turkey abstract the generation of gas in selected coal seams of the zonguldak basin northwestern turkey has been modelled by incorporating laboratory derived non isothermal reactions kinetics into the geothermal histories of the coal bearing strata kinetic parameters have been determined by programmed temperature open system pyrolysis of a low maturity 0 5 r 0 coal at three linnear heating rates of 0 1 0 7 and 5 0 k min the mathematical analysis of the bulk hydrocarbon evolution profiles assuming 25 first order reactions with activation energies regularly spaced between 46 and 70 kcal mol and a single pre exponential factor a yielded a value of a 3 17 10 16 min 1 and a rather broad hydrocarbon potential vs activation energy distribution with a maximum at 55 kcal mol geological time temperature relationships have been reconstructed by use of the basin modelling technique depending on the location within the basin of the wells studied and on the geological history of the coal bearing sediments the simulation procedure resulted in a predicted gas generation of up to 40 mg per g of coal

hoek brown parameters for predicting the depth of brittle failure around tunnels a review of underground openings excavated in varying rock masstypes and conditions indicates that the initiation of brittlefailure occurs when the damage index di expressed as theratio of the maximum tangential boundary stress to the laboratoryunconfined compressive strength exceeds approx0 4 when thedamage index exceeds this value the depth of brittle failure around a tunnel can be estimated by using a strengthenvelope based solely on cohesion which in terms of thehoek brown parameters implies that m 0 it is proposed that inthe brittle failure process peak cohesion and friction are notmobilized together and that around underground openings thebrittle failure process is dominated by a loss of the intrinsiccohesion of the rock mass such that the frictional strengthcomponent can be ignored for estimating the depth of brittlefailure an essential component in designing support for theopening case histories were analyzed using the hoek brownfailure criterion with traditional frictional parameter

a case study on large deformation failure mechanism of deep soft rock roadway in xin an coal mine china abstract large deformation of soft rock roadway has always been a major difficulty in deep mining practices this paper describes a case study of the failure mechanisms and stability control technology of deep roadway with soft rock mass in xin an coal mine in gansu province china rock mass properties around the roadway are evaluated using geological strength index gsi based on the field data and the mechanical properties of intact rock specimens the universal discrete element code udec software program is adopted to establish the numerical model of a ventilation roadway in xin an coal mine and the micro parameter calibration is conducted with the rock mass properties the failure process of roadway under unsupported and primary support conditions is simulated the deformation stress and crack evolution characteristics were clearly illustrated failure first appears around the roadway surface because there is a high stress concentration around the roadway surface after excavation the failure area propagates further into the deep surrounding rock as the stresses applied on the surface gradually decreases finally resulting in a large zone of stress relaxation there exists a large scale of tensile failure in the shallow rock which leads to swelling and fracturing around the roadway the primary support is low in strength with no support in the floor which results in serious floor heave side shrinking and roof subsidence a new bolt cable mesh shotcrete shell combined support is proposed to support the ventilation roadway the monitoring data in the experiment section show that the new support design successfully controls the large deformation of the roadway which can provide helpful references for support designing of engineering in deep soft rock roadway

global structure of the lunar tide in ionospheric total electron content 1 the global structure of the lunar tide in the ionosphere is studied based on observations of the global positioning system gps total electron content tec the unprecedented spatial and temporal resolution afforded by the gps tec observations enables illustration of the latitude longitude solar local time and seasonal variability of the lunar tide in the ionosphere based on analysis of the multi year mean from 1999 2008 the dominant component is generally the semidiurnal lunar tide however a significant diurnal variation is also observed in some instances the semidiurnal component achieves a maximum amplitude of 6 in the equatorial ionization anomaly crest regions and a slight hemispheric asymmetry is present with larger amplitudes in the northern hemisphere furthermore the maximum amplitudes in the semidiurnal lunar tide are found to occur during northern hemisphere winter and during 9 15 solar local time during certain years a secondary maxima in solar local time is also observed demonstrating the influence of the lunar tide on the prereversal enhancement lastly the observations reveal significant longitudinal variability in the semidiurnal lunar tide that is most prominent between november and february the presence of a longitudinal variation reveals the existence of nonmigrating components in addition to the dominant migrating semidiurnal lunar tide

developments in the design of tunnels and caverns in the triassic rocks of the sydney region abstract details are given of the analytical methods used to design rockbolt and shotcrete support for tunnels and large span caverns under relatively low cover in the near horizontally bedded triassic sandstones of the sydney region the paper provides a concise description of the engineering geology of the sydney sandstones because it is fundamental to tunnel support design that a valid geological model be the basis of any analytical design equations are provided which allow calculations of the lengths density and capacity of rockbolts for support in this geological environment the paper also discusses the design approach adopted for support of tunnels and caverns which are at sufficient depth to generate compressive and shear failure of the rock mass so called true rock pressure

lunar tide in the equatorial f region vertical ion drift velocity vertical ion drift velocity data from jicamarca have been analyzed for a lunar semidiurnal tide using a least squares fitting method amplitudes of up to 6 m s 1 are obtained with phases in agreement with lunar tidal determinations of other associated physical parameters variations between season solar activity and day to night are also examined generally amplitudes are larger in the southern summer much of the phase variation with season is very similar for solar maximum and minimum years there is a summer to winter phase change that is most distinct at solar maximum nighttime a day to night phase reversal can also been seen in some seasons hints of this are also found in the lunar tide in the f region height and in the magnetic variations at huancayo

lunar tide in the equatorial electrojet in relation to stratospheric warmings 1 the relationship between sudden stratospheric warmings ssws and large amplitude lunar tides in the equatorial electrojet eej is studied analysis of ground magnetometer data shows that the lunar tide in the eej is maximum during the northern winter season except in the pacific ocean region since ssws are also a northern winter phenomenon it is suggested that the relation between the large lunar tide in the eej and the ssw may possibly be coincidental the lunar tide in the geomagnetic variations at huancayo is anomalously large compared with other eej stations an examination of geomagnetic variations at eej stations during ssw events shows that afternoon counter electrojets are frequently present at new moon and full moon though the relationship is sometimes broken the observation of large lunar eejs when no ssw is present and of various different delay times suggests that other atmospheric processes are likely to be in play

responses of quasi 2 day waves in the mlt region to the 2013 ssw revealed by a meteor radar chain we present an analysis of the responses of quasi 2 day waves qtdws to the 2013 sudden stratosphere warming ssw in the mesosphere and lower thermosphere mlt region the study is based on data collected by a meteor radar chain along the 120 e meridian in the northern hemisphere which consists of four stations at mohe 52 5 n 122 3 e beijing 40 3 n 116 2 e wuhan 30 5 n 114 6 e and sanya 18 3 n 109 6 e it is the first time that an enhancement of the qtdw in the neutral wind during the 2013 ssw is observed in the midlatitudes in the northern hemisphere during the ssw the amplification of the qtdw in the low latitudes is the most prominent and the direction of the mean zonal wind shows clear reversion from eastward to westward the consistent variations of the qtdws and the mean neutral wind at the four stations are very likely associated with the ssw

the interplay of groundwater and magmatic fluids in the formation of the cassiterite sulfide deposits of western tasmania abstract the cassiterite sulfide deposits of western tasmania are spatially and temporally related to devonian granitoids the stable isotope and fluid inclusion data of these deposits are best explained by a genetic model in which sn is leached from the granites by reduced non magmatic fluids mixed with late stage magmatic fluids these fluids mineralize the overlying dolomite horizons and subjacent faults by a combination of wallrock and boiling induced reactions the model requires co incidental release of volatiles and ingress of groundwaters to sustain the leach mechanism this implies some specific structural deformational controls on the process and an intimate association between cassiterite sulfide deposits and volatile rich granites the sulfur isotope data show a wide range in values from about 2 to 20 per mil and are explained in terms of a near zero magmatic component and three heavier country rock sources the precambrian oonah formation the crimson creek formation and the mount read volcanics following this interpretation the heavy sulfur isotope values from the heemskirk granite hajitaheri 1985 and the federal bassett fault at renison kitto 1994 indicate ingress of groundwater into the granites salinities of fluid inclusions from the deposits show a restricted range around 5 to 15 weight percent nacl equivalent compared with the range shown by inclusions from alteration zones within the granites around 5 to 40 weight percent nacl equivalent it is suggested that the wide range of salinities in the granites is generated in the critical region of the nacl h 2 o system at temperatures around 400 to 500 c and pressures around 400 to 500 bars the limited range of salinities in the deposits reflects cooling to sub critical conditions cooling through the critical region promotes homogenization of groundwater and magmatic vapor and brine condensation of magmatic volatiles within this zone of mixing maintains acidity and promotes fluid rock reaction the geochemistry of the granites underlying the renison bell area bajwah et al 1995 is interpreted in terms of two granites the geological relationships indicate the more mafic phase the renison granite was intruded by the more fractionated pine hill granite fluids from the pine hill granite sericitised and tourmalinized both the renison granite and pine hill granite along their mutual contact generating a broad north east trending zone of alteration this contact may have been offset by the federal bassett fault before the renison deposit was formed it is suggested that groundwater flow was essentially constrained within this nw se trending structure and subsidiary structures magmatic volatiles emanating from deep within the pine hill granite acidified the reduced groundwater and promoted leaching of the granite the siting of the renison deposit on the margin of the pine hill granite is consistent with a strong up flow zone on the margin of a cooling pluton the very constant s isotope signature in the deposit is consistent with a large scale homogenization process operating over a sustained period the very large size of the renison deposit is accounted for by a long lived groundwater system maintained by the high heat flow from a fractionated granite

ionosphere variability during the 2009 ssw influence of the lunar semidiurnal tide and mechanisms producing electron density variability to investigate ionosphere variability during the 2009 sudden stratosphere warming ssw we present simulation results that combine the whole atmosphere community climate model extended version and the thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm the simulations reveal notable enhancements in both the migrating semidiurnal solar sw2 and lunar m2 tides during the ssw the sw2 and m2 amplitudes reach 50 m s 1 and 40 m s 1 respectively in zonal wind at e region altitudes the dramatic increase in the m2 at these altitudes influences the dynamo generation of electric fields and the importance of the m2 on the ionosphere variability during the 2009 ssw is demonstrated by comparing simulations with and without the m2 time gcm simulations that incorporate the m2 are found to be in good agreement with jicamarca incoherent scatter radar vertical plasma drifts and constellation observing system for meteorology ionosphere and climate cosmic observations of the maximum f region electron density the agreement with observations is worse if the m2 is not included in the simulation demonstrating that the lunar tide is an important contributor to the ionosphere variability during the 2009 ssw we additionally investigate sources of the f region electron density variability during the ssw the primary driver of the electron density variability is changes in electric fields changes in meridional neutral winds and thermosphere composition are found to also contribute to the electron density variability during the 2009 ssw the electron density variability for the 2009 ssw is therefore not solely due to variability in electric fields as previously thought

quiet variability of equatorial e b drifts during a sudden stratospheric warming event 1 we present strong evidence that during the january 2008 minor sudden stratospheric warming ssw event the equatorial vertical e b drifts exhibit a unique and distinctive daytime pattern we do not think one event causes the other however both events might be related through the global effects of planetary waves the drifts were measured by the jicamarca incoherent scatter radar located under the magnetic equator we have observed an anomalous temporal variation of the vertical e b drifts during the minor ssw event showing a semidiurnal variation with very large amplitudes lasting for several days large differences in the e b drifts were observed during a period of large increase of temperature and a large decrease of mean zonal wind in the high latitude stratosphere 60 90 n this high correlation is an unexpected finding which might shed new light on sources and mechanisms of quiet time ionospheric variability

physical modeling of an underground roadway excavation in geologically 45 inclined rock using infrared thermography abstract physical modeling of excavation of a roadway tunnel in the geologically 45 inclined rock strata by using a newly developed physical modeling approach the so called physically finite elemental slab assemblage pfesa together with infrared ir thermography were conducted for visualization and observation of the progressive development of the excavation damaged zone edz the excavation was schemed as two phases i e phase 1 the full face excavation and phase 2 the staged excavation the experiment was performed under unbalanced confinement found in underground coal mining the relative temperatures of the excavation zone were mapped by the ir camera in real time and over the entire field into thermography series which were processed using such procedures as statistics noise removal and spectral frequency analysis for image feature extraction irt defined as the statistical mean of the thermography matrix was used as a measure of rock responses characterizing the full face excavation and the staged excavation as a multi linearity and nonlinearity processes respectively by its time marching scheme the temporal and spatial evolutions of the edz were described in detail by the denoised thermographies directional propagations of the excavation induced stress wave were characterized by the spectral frequency analysis of the resultant thermographies

upper mesospheric lunar tides over middle and high latitudes during sudden stratospheric warming events in recent years there have been a series of reported ground and satellite based observations of lunar tide signatures in the equatorial and low latitude ionosphere thermosphere around sudden stratospheric warming ssw events this lower atmosphere ionosphere coupling has been suggested to be via the e region dynamo in this work we present the results of analyzing 6 years of hourly upper mesospheric winds from specular meteor radars over a midlatitude 54 n station and a high latitude 69 n station instead of correlating our results with typical definitions of ssws we use the definition of polar vortex weaking pvw used by zhang and forbes 2014 this definition provides a better representation of the strength in middle atmospheric dynamics that should be responsible for the waves propagating to the e region we have performed a wave decomposition on hourly wind data in 21 day segments shifted by 1 day in addition to the radar wind data the analysis has been applied to simulations from whole atmosphere community climate model extended version and the thermosphere ionosphere mesosphere electrodynamics general circulation model our results indicate that the semidiurnal lunar tide m2 enhances in northern hemispheric winter months over both middle and high latitudes the time and magnitude of m2 are highly correlated with the time and associated zonal wind of pvw at middle high latitudes m2 in the upper mesosphere occurs after before the pvw at both latitudes the maximum amplitude of m2 is directly proportional to the strength of pvw westward wind we have found that m2 amplitudes could be comparable to semidiurnal solar tide amplitudes particularly around pvw and equinoxes besides these general results we have also found peculiarities in some events particularly at high latitudes these peculiarities point to the need of considering the longitudinal features of the polar stratosphere and the upper mesosphere and lower thermosphere regions for example during ssw 2009 we found that m2 enhances many days before pvw which is not in agreement with most of our results

study on deformation failure mechanism and support technology of deep soft rock roadway abstract the roadway support has always been a difficult problem in the mining engineering especially in the deep soft rock roadway whether it can provide endurable and effective support directly affects the safety production and sustainable development of the mine in order to solve the supporting issues it is necessary to make the deformation failure mechanism of deep soft rock roadway clear this paper describes a case study of the deformation failure mechanism and support technology of deep roadway with soft rock mass in no 2 mine zone of jinchuan mine that is located in gansu province china based on a detailed field investigation and previous research experience the modes influencing factors laws and mechanisms of deformation failure in the roadway are summarized then the primary combined supporting scheme double layer bolt mesh shotcrete and u shaped steel is evaluated through numerical simulation calculation and onsite experiments to make up for the shortcomings of the primary support an improved combined supporting scheme double layer long bolt mesh shotcrete and cfst concrete filled steel tube is proposed the results of numerical simulation field monitoring and economic analysis show that the new support can control the deformation of the roadway effectively and has a high cost performance finally several suggestions for supporting in deep soft rock roadway are put forward aiming at serve as a reference for other engineering

investigation on the variability of the geomagnetic daily current during sudden stratospheric warmings the magnetic field records of the magnetometer networks in the american east asian australian and european african sectors were employed in this present work we used them to investigate equatorial electrojet eej counter electrojet cej tidal variability in eej strength and ionospheric current during the 2005 2006 and 2008 2009 sudden stratospheric warming ssw events in addition to the well investigated tidal variability in eej strength over the american and east asian sectors we investigated that of the african sector for the first time interestingly the tidal components in eej strength during both ssw events clearly exhibit marked longitudinal differences with high moderate and low amplitudes in the american east asian and african sectors respectively an exception found around day 71 in the african sector after the 2008 2009 ssw event had higher solar diurnal tidal component as compared to that of the asian sector over the american sector solar and lunar semidiurnal tides were strongly associated with cej current during both ssw events whereas at the african and east asian sectors such variabilities are not evident a solar diurnal tidal component was strongly related to a reduction in the eej strength over the east asian sector in addition a prolonged period of cej occurrence that begins during the ssw precondition and ends when the ssw was evolving characterized the african sector during both ssw events there is a steady shift in phase at later hours when both ssw events are evolving

c nofs observations of the equatorial ionospheric electric field response to the 2009 major sudden stratospheric warming event 1 we present new observations made by the coupled ion neutral dynamics investigation cindi ion velocity meter ivm instrument onboard the communication navigation outage forecasting system c nofs satellite that show the effects of the january 2009 sudden stratospheric warming ssw event on equatorial electric fields we have used ivm observations to construct composite curves of mean equatorial vertical plasma drifts as a function of local time and longitude sector these curves show large upward vertical drifts during morning hours and downward drifts during afternoon our analysis indicates that this pattern could be observed over the range of longitudes where adequate ivm measurements were available from approximately 165 e to about 315 e longitude a clear day to day quasi deterministic variability in the drifts is also observed with the transition from upward to downward drifts occurring at increasing local times from 25 to 30 january 2009 the analysis also suggests some level of longitudinal variability in the magnitude of the drifts these in situ observations are in good agreement with previous ground based measurements of the response of equatorial electric fields to ssw events in particular we found that ivm drift measurements centered around 285 e depart significantly from climatological values but agree exceptionally well with ground based measurements of vertical drifts made by the jicamarca incoherent backscatter radar overall the results agree well with previous studies of ssw events demonstrate the usefulness of the ivm observations and motivate further studies of the variability of the equatorial ionosphere using c nofs

analysis of roof fall hazards and risk assessment for zonguldak coal basin underground mines the roof fall hazards are frequent problems of underground coal mines which are generally unpredictable due to the associated uncertainties these uncertainties which arise from geological and stress conditions and mine environment make the control of roof fall hazards difficult in underground coal mines the most efficient method for coping with uncertainties in roof fall hazards is the use of risk assessment techniques in this study a risk assessment and management methodology is proposed for roof fall hazards in underground mines of the zonguldak coal basin the annual rates of roof falls obtained from the five mines in the basin are statistically analyzed the components of risk which are the probability of roof fall and consequences of roof fall hazard are identified and quantified the probability of roof fall is computed by fitting a distribution function to the annual roof fall while the consequences of roof falls are quantified based on a cost model then a decision analysis methodology for evaluating the performance of possible alternative action to be taken in order to decrease the risk is developed the results show that the underground coal mines in the zonguldak coal basin have considerably high risk levels and hence require comprehensive risk management schemes

pore volume and surface area of the carboniferous coals from the zonguldak basin nw turkey and their variations with rank and maceral composition abstract the macropore volume micropore volume and surface area of carboniferous bituminous coals from the zonguldak basin in northwestern turkey have been determined furthermore variations of these coal properties with rank and maceral composition have been investigated helium density mercury porosimetry and low pressure co 2 gas adsorption measurements were performed in order to determine the pore volumes and the surface area of coals helium and mercury densities of the coals vary between 1 28 1 41 and 1 11 1 32 g cm 3 respectively the macropore volume determined by mercury porosimetry varies between 0 0065 and 0 0687 cm 3 g for the interpretation of the adsorption mechanism and for the determination of the respective pore volumes and surface areas langmuir and dubinin radushkevich d r equations were applied the micropore volume and respective micropore surface area values are ranging from 0 0139 to 0 0524 cm 3 g and from 42 to 160 m 2 g respectively the langmuir monolayer volume which can be considered as an estimate of the gas adsorption capacity varies between 14 and 37 cm 3 g the corresponding specific surface area values range from 80 to 216 m 2 g a comparison of pore volumes with rank and maceral composition of coals indicated that micropore volume decreases with increasing maturity up to a value of 1 0 r o and then increases with further increase of coal rank a similar trend is also observed with langmuir monolayer volume and specific surface area in general an indicative correlation could not be observed between maceral composition and pore volume and surface area however a weak correlation does exist between langmuir monolayer volume and vitrinite content

lunar gravitational atmospheric tide surface to 50 km in a global gridded data set the lunar gravitational semidiurnal atmospheric tide l2 is detected in the geopotential field in the era interim reanalysis by regressing the data for each of the four daily analysis times onto periodic lunar half synodic cycle time series and differencing the resulting regression maps a robust pattern dominated by zonal wave number 2 emerges which agrees with tidal theory and with previous observational studies based on station data in terms of its amplitude phase and seasonality at the earth s surface above the 100 hpa level the tidal signal amplifies with height and it is downward propagating below that level it is almost barotropic the l2 signal is resolvable even in data for individual months of individual years monthly time series of tidal amplitude and phase exhibit a well defined pattern of seasonality year after year since the era forecast model has no l2 gravitational forcing the source of its l2 signal must be in the observations

lunar tides in total electron content over brazil using data from global navigation satellite systems dual frequency receivers the lunar tides were studied in the ionospheric total electron content tec over brazil from 2011 to 2014 in order to calculate the amplitudes and phases of the lunar tides quiet magnetic days within a 27 day window has been used to remove the solar rotation effects relative residuals tec were calculated by performing a spectral analysis by removing the solar tide contributions lastly a lunar month size window was used to calculate the amplitude and phase of the lunar components lunar diurnal tide amplitudes showed a semiannual variation with maximum in the equinox months for almost all latitudes while lunar semidiurnal amplitudes were larger in december and january and may be related to sudden stratospheric warming events both components did not display significant longitudinal variation what could be due to the short range of longitude 30 degrees lunar diurnal amplitudes were basically uniform over brazil while lunar semidiurnal amplitudes showed some peaks over the equatorial ionization anomaly crest and minimum values near the magnetic equator

coupling between mesosphere and ionosphere over beijing through semidiurnal tides during the 2009 sudden stratospheric warming 1 sudden stratospheric warming ssw in the winter of 2008 2009 is the strongest recorded ssw event the enhancement in semidiurnal variation of ionospheric tec total electron content with phase shift forward is shown during 22 to 27 january 2009 based on the tec observations in beijing 40 30 n 116 19 e geographic 39 73 n dip latitude we focus on finding the reason for the tec variation winds observed by an all sky meteor radar in the same observatory are used to study mesospheric variation the semidiurnal solar tide in the mesosphere starts to increase before the ssw and maintains oscillation with period 16 20 days during the ssw the semidiurnal lunar tides in tec and wind start to increase on 17 and 15 january respectively although the semidiurnal lunar tide in tec over beijing almost dies out on 1 february that over equatorial ionospheric anomaly crest does not vanish until 15 february when lunar tide in wind tends to be very weak the maximum of lunar tide in wind appears on 2 february at 96 km with amplitudes of 15 m s and 21 m s for zonal and meridional winds the phase comparison shows that lunar tides in tec and zonal wind reach their maxima at almost the same time which is 2 4 h lag behind the meridional wind the coupling between the mesosphere and ionosphere contributes to the semidiurnal variation of tec through both solar and semidiurnal lunar tides the enhancement in semidiurnal lunar tide is responsible for the tec peak shift forward during the ssw

determination of underground mining induced displacements using gps observations in zonguldak kozlu hard coal basin abstract mining activities cause horizontal and vertical movements on the earth s surface as well as in underground which give rise to environmental economical judicial and urbanization problems these movements or displacements the results of collapsing vertical displacement swelling slope change bending and cracking are referred to as mining subsidence which depends on the depth and dimension of mined area production methods underground operating speed time and geological structure of area the mining subsidence eventually affects the development of cities and city life by causing damages and destruction on buildings and structures on the surface in order to study the displacements caused by on going mining activities city of zonguldak its town kozlu and its near surroundings are chosen since they constitute the center for hard coal basin in turkey for 160 years with a population of 300 000 and an area of 80 km2 this study details the results from a gps network conducted in the basin to determine the horizontal displacements on the surface created by the mining activities the displacement results obtained from this study have been found to range from 10 to 78 mm with 4 4 to 7 9 mm rmse values these results indicate that the surface of the basin is under these effects today

tunneling in squeezing rock the bolu tunnel anatolian motorway turkey abstract the bolu tunnel is subject to considerable deformation due to stress related failure in the rock mass in thrust zones and strike slip faults that transect the tunnel these deformations resulted in some serious geotechnical problems which were overcome either by flexible or extremely heavy support systems the heavy system was used to prevent or bring under control the large deformations that would take place during excavation whereas the flexible method allows the deformations to develop without restraint the heavy support system was used in thrust fault zones and in flysch zones in the bolu tunnel and produced more successful results in comparison to the flexible support system a brief explanation of the tunnel collapse in the duzce earthquake is also provided

re profiling of a squeezing tunnel considering the post peak behavior of rock mass abstract in problems involving large deformation one of main concerns in rock engineering is the occurrence of a heavily reduction in tunnel section and even shield jamming in this paper a rigorous theoretical model is established to characterize the process of tunnel re profiling works in heavily squeezing ground to re construct the desired profile based on the finite strain approach and lagrangian material description the post peak behavior of rock mass and elasto plastic strains in plastic zone during each excavation process are taken into account therefore the proposed method enables to quantify the repetitive disturbances to a plastified surrounding rock and accumulated degradation of material properties a numerical procedure is presented in which the history dependent behavior and path of material point in strain softening rock mass during the entire excavation process are determined via our previous work in combination with incremental algorithm and spatial interpolation the discrepancy from the accurate solution induced by the negligence of elastic strains in all plastic zones is investigated by comparing the present results with the existing study an extensive computations are then carried out to clarify some practical questions including the effects of post peak behavior ground condition and old temporary support on the repetitive re profiling the variation of rock pressure developing on a rigid support after excavation and the required minimum over excavation size to achieve the desired profile also the effectiveness of advancing a pilot tunnel is investigated under different post peak and geometrical conditions in order to illustrate the applicability of the construction method in squeezing ground

empirical estimation of strength of jointed rocks traversed by rock bolts based on experimental observation abstract engineering behaviour of jointed rocks is substantially incompetent as compared to intact rocks due to the presence of joints rock bolts are routinely used to reinforce jointed rocks at project sites the assessment of the strength behaviour of bolt reinforced jointed rock is a challenging task due to the complex interaction between the joints and the bolts the present paper attempts to resolve this issue through an experimental study natural rock cores with a natural joint and synthetic rock cores with smooth joint have been tested under uniaxial compression the tests have been performed on specimens without and with bolt grouted steel bolt was used to reinforce the rock results from the tests indicate that the provision of the bolt alters the failure mode of jointed rock and enhances the strength and modulus values strength and modulus of the reinforced rock were found to be correlated with each other it is proposed that the strength of reinforced rock can be obtained from strength and modulus of the intact rock and the modulus of the reinforced rock the intact rock strength and modulus may be obtained from laboratory tests and the modulus of the reinforced rock may be obtained by back analysing the deformations observed in the field sakurai s critical strain concept has been analysed and it is observed that the correlations suggested through proposed empirical approach closely commensurate with critical strain approach and hence give scale free results

numerical and theoretical study of bi planar failure in footwall slopes abstract bi planar failure is the commonest type of failure in steep and high footwall slopes this paper presents an investigation of the bi planar failure mechanism and a stability analysis model for footwall slopes based on the study of eleven diabase mines in hunyuan county shanxi province china first a detailed investigation of the site and tests were carried out to obtain a geological model and calculation parameters for the slope then the failure process in footwall slopes was investigated by a trigon approach performed using the universal distinct element code udec software package a mechanism was then obtained for bi planar compression shear failure by combining the results obtained for the stress displacement and crack development subsequently based on the limit equilibrium and frictional plasticity theories a new columnar mechanical model was proposed for bi planar footwall slope failure the results demonstrate that the udec trigon approach was well suited to simulating bi planar failure in steep and high footwall slopes employing this approach a sliding failure surface that initiates develops and propagates in the discontinuity and intact rock could be correctly captured and the evolution of the damage in the toe of the slope could be quantitatively investigated the results also indicate that shear failure first occurs at persistent discontinuities and then compression shear failure occurs in the intact rocks in addition the failure surface of the rock emanates from the toe of the slope is oriented upwards at an angle to the persistent discontinuity thus forming the through sliding surface this angle can be determined using frictional plasticity theory the critical heights and safety factors of footwall slopes could be readily obtained by employing this new columnar mechanical model giving results that are consistent with the results of numerical simulations furthermore the results of a parameter sensitivity analysis show that the dip angle of the toe breakout surface increases as the slope angle increases however the angle between the toe breakout and internal shear surfaces remains unchanged as the slope angle increases moreover the critical height of the footwall slope decreases linearly as the slope angle increases the method proposed provides theoretical guidance for the stability analysis of steep and high footwall slopes the results produced should also help engineers to gain a better understanding of the mechanisms of bi planar failure in such rock slopes

improved compound support system for coal mine tunnels in densely faulted zones a case study of china s huainan coal field abstract when tunnelling in densely faulted zones of coal mines serious deformation often occurs due to adverse geological conditions such as extremely broken and weak rock mass high tectonic stress fissure water to investigate a more efficient support strategy for tunnels passing through densely faulted zones a tunnel in china s huainan mining area is taken as an experimental site to study an improved support method some key factors associated with the stability of tunnels in the densely faulted zone are analysed based on the analysis of failure characteristics of a previously excavated tunnel a detailed procedure for the improved support method is proposed in which a long pipe pre grouting method together with a new kind of grouting cable are applied finally the improved support strategy is implemented in the experimental tunnel the monitoring results suggest that serious deformation is avoided and the improved compound support method is feasible for tunnels in densely faulted zones

effects of mining subsidence on masonry buildings in zonguldak hard coal region in turkey gallerias are the underground constructed results of mining as these space in underground layers collapse horizontal and vertical ground movements occur and movement which may reach the earth s surface are known as mining subsidence the result of underground displacement may cause surface ground movement which can be detrimental to masonry buildings especially in hard coal regions thorough familiarity with general and regional characteristics of an affected area can assist reduction of the effects zonguldak and the nearby settlement area with a population of 300 000 constitute the centre of a hard coal basin where extensive mining has a history extending through 160 years mining constitutes the main economic activity in this region and consequently influences every aspect of life this study s intent is to identify the effects of mining subsidence on masonry buildings in the mining area of kozlu zonguldak turkey and illustrate them with selected images of damaged masonry buildings also included are satellite and mining galleria images

investigating the effect of simultaneous extraction of two longwall panels on a maingate gateroad stability using numerical modeling abstract in longwall mining method the stability of the maingate and tailgate gateroads is of great importance because these excavations are used for essential services such as ventilation and transportation the aim of this paper is to develop a numerical model to investigate the stability of a maingate gateroad named p8 maingate during caving and extraction of p7 and p8 coal panels of tabas parvadeh underground mine stability analysis is carried out by critical shear strain criterion zone plasticity conditions support system efficiency and strength stress ratio conditions using flac3d a software based on finite difference numerical methods in the critical shear strain criterion method the stability analysis is conducted by comparing the shear strain increments of the element in the model and sakurai critical shear strain in the second stability analysis method based on zone plasticity the zones indicating shear plastic failures are the potential instability causing regions in the support system efficiency method the applied load and pressure are compared to the yielding strength of the support systems to check their stability in the strength stress ratio ssr method a safety factor is determined for the gates and the strength versus stress plots of the gates are assessed to control the stability condition the results of numerical modeling indicate the stability of the p8 maingate using these methods the modeling results are then compared to the instrumentation data to investigate the consistency where a good agreement was observed

study on electrical potential inversion imaging of abnormal stress in mining coal seam during the mining activities coal rock dynamic disasters have caused grievous casualties and massive property losses it is the severe problem for regional monitoring of abnormal stress electrical potential ep can be produced on coal rock under loading and its response is related closely with the loading stress and damage evolution meanwhile electric field inversion has the advantage to realize regionalization monitoring in the space to identify the abnormal stress localization characteristics in mining coal seam after theoretical derivation the strategy of ep inversion imaging on is studied under bilateral model further simulation experiment of coal rock under loading is conducted the abnormal probability zones of sample can be identified with ep inversion imaging while it corresponds with severe damage zones with significant crack propagation it can be utilized to reveal the localized characteristics of damage and failure of coal rock spatially finally the results of ep inversion in the mining coal seam indicate that the abnormal probability zones can be considered as stress concentration and dynamic hazard areas its effectiveness is verified by microseismic monitoring and rock burst hazard assessment the study provides a new idea to monitor abnormal stress zone regionally and forecast dynamic disasters in the field

empirical and numerical analyses of support requirements for a diversion tunnel at the boztepe dam site eastern turkey abstract this paper presents the engineering geological properties and support design of a planned diversion tunnel at the boztepe dam site that contains units of basalt and tuffites empirical theoretical and numerical approaches were used and compared in this study focusing on tunnel design safety rock masses at the site were characterized using three empirical methods namely rock mass rating rmr rock mass quality q and geological strength index gsi the rmr q and gsi ratings were determined by using field data and the mechanical properties of intact rock samples were evaluated in the laboratory support requirements were proposed accordingly in terms of different rock mass classification systems the convergence confinement method was used as the theoretical approach support systems were also analyzed using a commercial software based on the finite element method fem the parameters calculated by empirical methods were used as input parameters for the fem analysis the results from the two methods were compared with each other this comparison suggests that a more reliable and safe design could be achieved by using a combination of empirical analytical and numerical approaches

the unusual midwinter warming in the southern hemisphere stratosphere 2002 a comparison to northern hemisphere phenomena a strong midwinter warming occurred in the southern hemisphere sh stratosphere in september 2002 based on experiences from the northern hemisphere nh this event can be defined as a major warming with a breakdown of the polar vortex in midwinter which has never been detected so far in the sh since observations began at the earliest in the 1940s minor midwinter warmings occasionally occurred in the sh but a strong interannual variability as is present in winter and spring in the nh has been explicitly associated with the spring reversals a detailed analysis of this winter reveals the dominant role of eastward traveling waves and their interaction with quasi stationary planetary waves forced in the troposphere such wave forcing finally leading to the sudden breakdown of the vortex is a familiar feature of the northern winter stratosphere therefore the unusual development of this antarctic winter is described in the context of more than 50 arctic winters concentrating on winters with similar wave perturbations the relevance of preconditioning of major warmings by traveling and quasi stationary planetary waves is discussed for both hemispheres

study on the fracture characteristics of thick hard limestone roof and its controlling technique the taiyuan group is one of the coal bearing formations in shanxi province in which coal resource is extremely abundant no 15 coal seam is the main minable coal seam in taiyuan group and it develops with thick hard limestone roof which is a threat to safe and efficient mining because of the roof failure aiming at the geological setting of no 15 coal seam and its surrounding rock we conduct an experimental study on physical and mechanical properties of no 15 coal seam and its floor as well as roof and we also have an underground measurement on roof fracture width and floor loose range of headgate based on experimental results and fracture mechanics theory we established a thick hard limestone roof cracking model and discussed the factors that affect roof fracture initiation and extension the research results demonstrate that roof fracture height is affected by the horizontal stress surrounding rock deformation roof mechanical strength and roof span the deformation of wall and floor will induce the roof fracture extension the roof fracture extension is high in stress concentration area under the upper coal face residual coal pillar the fracture height can be effectively controlled by reducing surrounding rock loose range and improving mechanical strength of walls

collision related fore arc and back arc evolution of the northern sunda arc abstract comparison with other arc systems suggests that in the fore arc area of the northern sunda arc emplacement of chromite and jadeite bearing serpentinite melange diapirs and deposition of olistostromes were caused by campanian collision with a continental fragment since underthrust eastwards beneath the arc the age and position of east directed thrusts and associated tin granites in the continental back arc area implies that thrusting and generation of granites were genetically related to the collision and that the back thrusts were coupled to the fore arc thrusts by a decollement beneath the fore arc basin and magmatic arc subsidence and sedimentation in the fore arc basin succeeded collision and rise of the back arc shan plateau possibly resulted from late cenozoic relaxation of collision related compressive stress

effect of sudden stratospheric warming on lunar tidal modulation of the equatorial electrojet 1 using the equatorial electrojet eej peak current intensity as deduced from champ magnetic observations from the years 2001 through 2009 we investigated the relationship between sudden stratospheric warming ssw and lunitidal signatures in the tropical ionosphere there is a practically one to one correspondence between midwinter ssw periods and the strongest 13 day modulation of the eej strength as observed by champ that is all the midwinter ssw periods from december 2001 to august 2009 were accompanied by an enhanced 13 day modulation of the eej strength no other geophysical phenomenon brought about as strong a 13 day modulation as those of the midwinter ssw periods during each midwinter ssw period the amplified 13 day modulation of the eej strengths starts roughly within 1 week around the first peak in stratospheric temperature difference an oscillation with a period of 13 26 days is predicted by the lunitidal equation when considering the precession of the champ orbit when fitting the lunitidal equation to the eej modulations during the midwinter ssw periods consistent phase delays of 4 4 0 3 days of the tidal signal emerge for all the cases the results suggest that the pronounced 13 day modulation of the eej strength is related to an enhancement of the lunar tide in the ionosphere by the ssw effect