variations of hydraulic properties of granular sandstones during water inrush effect of small particle migration the evaluation of the hydraulic properties evolution of granular sandstones in relation with groundwater inrush within faults is an important issue for mining engineering applications this paper presents the results of an experimental investigation of small particle migration from granular sandstone samples under different original porosities particle size compositions and water flow pressures a new rock testing system has been setup to carry out the tests based on the results it is observed that the overall permeability evolution during the tests can be divided into four different phases including i re arrangement of large rock fragments ii water inrush with substantial particle migration iii continued moderate particles seepage and iv steady state water flow the crushing of edges and corners of large rock fragments and the evolution of the fracture network has mainly been observed in the first two phases of the tests the results indicate that the migration of small particles has an essential effect on permeability and porosity increase during water inrush through fractured sandstone the samples with higher original porosity higher percentage of fine particles in their formation and under higher water flow pressures achieve higher permeability and porosity values when the test is complete furthermore using the measured data the performances of a number of empirical models for permeability evolution in fractured porous media have been studied the prediction results indicate that not all of the fractures in a sample domain contribute in small particle migration there are parts of the fracture network that are not effective in particle flow a sample with less original porosity more fine particles and under lower water pressure shows less ineffective fractures therefore using the concept of the effective porosity fracture is sufficient enough for the flow calculation

origin of groundwater salinity and hydrogeochemical processes in the confined quaternary aquifer of the pearl river delta china summary the pearl river delta prd located in the coastal area of south china contains a large confined quaternary aquifer this aquifer has been identified to have high concentrations of total dissolved solids ranging from 1 g l in the inland area to 26 8 g l near the southeast shoreline this work aims to investigate the origin of groundwater salinity and the major hydrogeochemical processes controlling the groundwater evolution in the confined basal aquifer of the prd a total of 40 boreholes were drilled in the prd during 2007 2009 and groundwater samples were collected for major ion ca 2 mg 2 na k nh 4 cl so 2 4 and hco 3 and isotope d 18 o d 2 h 3 h d 13 c and 14 c analyses these analyses demonstrate that groundwater in the confined basal aquifer is recharged by local rainwater and seawater and seawater is the major salinity source for groundwater the contribution of seawater varies from less than 1 in the inland areas to 74 near the shoreline so 2 4 reduction and methanogenesis occur in this reducing confined aquifer the results of ion exchange show that mg 2 exchanges mainly with the nh 4 ion which is derived from the mineralization of sedimentary organic matter ion exchange between na

source location dependency site response in the taipei basin of taiwan by using hvsr analysis abstract techniques using horizontal to vertical spectral ratios hvsr have frequently been adopted in many studies particularly of seismic site amplification however the influence of source location on the hvsr is not previously well studied this paper studies the variation of the s wave hvsr in the taipei basin based on a variety of hypocenter locations the earthquake records are classified into three categories include depth azimuth and distance we report the s wave hvsr to have strong focal depth dependence for which the hvsr of the deep events are larger than shallow events besides the s wave hvsr in the northern and northeastern parts of the basin also displays source azimuthal dependence however there is no apparent difference in source distance dependence in contrast to the s wave hvsr the coda wave hvsr all showed no apparent difference for various earthquake hypocenter locations the synthetic modeling results support our idea that the cause of the variation of hvsr results for different earthquake focal depths is the different s wave angles of incidence into the basin based on the dependency of the site amplification on the focal depth a focal depth dependent empirical transfer function etf was established the focal depth dependent etf was verified to improve the accuracy of the ground motion prediction by using the stochastic method in this study we demonstrate that the source location effect especially the focal depth can significantly influence the s wave hvsr and therefore needs to be taken into account in site response investigation

numerical investigation of groundwater outbursts near faults in underground coal mines permeable geologic faults in the coal seam can cause intermittent production problems or unexpected amounts of groundwater outburst from the underlying aquifers with the acknowledgment of the basic mechanism for groundwater outbursts the groundwater outburst along the fault zones in coal mines are numerically investigated using rfpa a numerical code based on fem the fracture initiation propagation and coalescence in the stressed strata and the seepage field evolution in the stress field are represented visually during the whole process of groundwater outburst the numerically obtained damage evolution shows that the floor strata could be classified as three zones i e mining induced fracture zone intact zone and fault reactivation zone in which the intact zone is the key part for resisting groundwater outburst and directly determines the effective thickness of water resisting rock layer with understanding of the evolution of stress field and seepage flow in floor strata the groundwater outburst pathway is calibrated and the transformation of floor rock mass from water resisting strata to outburst pathway is clearly illuminated moreover it is shown that geometrical configuration including inclination angle of faults and seam drop along faults have an important influence on groundwater outburst finally based on geological hydrogeology survey and numerical results the mechanism analysis of groundwater outburst in an engineering case is studied which can provide significantly meaningful guides for the investigation on mechanism and prevention of groundwater outburst induced by faults in practice

numerical evaluation of land subsidence induced by groundwater pumping in shanghai to predict the future behavior of land subsidence in shanghai due to pumping of groundwater a numerical model is established in the proposed model groundwater flow in three dimensional conditions and soil deformation in one dimen sional conditions are calculated the model takes into account the multi aquifer aquitard hydrogeological condition of the soft deposit of shanghai the variation of the coefficient of compressibility and coefficient of hydraulic conductivity of the soils with the consolidation process are simulated relationships among land subsidence groundwater withdrawal volume and groundwater level are analyzed comparison between the measured value and calculated value shows that the model simulates the measured value fairly well the future of land subsidence behavior due to groundwater withdrawal is predicted and discussed via consideration of the variation of the following parameters in the future 30 years net withdrawn volume of groundwater pumping layer and pumping region resume un modele numerique est propose afin de predire le comportement futur d un affaissement de sol cause par le pompage de l eau souterraine a shanghai dans le modele propose l ecoulement de l eau souterraine en trois dimensions et la deformation du sol en une dimension sont calcules le modele considere la condition hydrogeologique multi aquifere aquitard du depot mou de shanghai les variations du coefficient de compressibilite et du coefficient de conductivite hy draulique des sols lors du processus de consolidation sont simulees les relations entre l affaissement du sol le volume de retrait de l eau souterraine et le niveau phreatique sont analysees des comparaisons entre les valeurs mesurees et calculees montrent que le modele peut simuler les valeurs mesurees relativement bien le comportement futur du sol en affaissement cause par le retrait de l eau souterraine est predit et discute en considerant les variations pour les prochains 30 ans pour les parametres suivants le volume net d eau souterraine retire la couche de pompage et la region de pompage mots cles pompage de l eau souterraine affaissement du sol ecoulement de l eau souterraine en trois dimensions consoli dation en une dimension prediction traduit par la redaction

mechanical behavior of groundwater seepage in karst collapse pillars abstract groundwater inrush has an impartible relationship with geological structures such as karst collapse pillars kcps which are widely distributed in north china in order to study the mechanism of groundwater inrush from coal seam floor the variable mass dynamics and nonlinear dynamics were introduced a mechanical model plug model is established to describe the behavior of water seepage flow in coal seam floor containing kcp the study shows that 1 if the mass of the kcp keeps steady the water seepage velocity in the kcp and the surrounding rocks will reach a constant value soon 2 if the mass of the kcp and the surrounding rocks increases by grouting etc the seepage velocity in the kcp and the surrounding rocks will reach its minimum value gradually and 3 if the mass of the kcp and the surrounding rocks decreases by scouring the flow velocity in the kcp and the surrounding rocks shows a monotone increase the water flow may change into pipe flow especially when a large number of the mass of the kcp and the surrounding rocks enters into goaf road which may lead to instable flow and cause groundwater inrush

field experiments and numerical simulations of confined aquifer response to multi cycle recharge recovery process through a well summary shanghai is one of the cities suffering from land subsidence in china land subsidence has caused serious financial losses thus artificial recharge measures have been adopted to compensate the drawdown in shallow confined aquifers and thereby control land subsidence in this study a multi cycle recharge recovery field experiment was performed to investigate the response of a shallow confined aquifer to artificial recharge through a well in the experiment a series of recharge recovery cycles with different recharge volumes and durations with and without artificial pressure were performed the water levels monitored in the recharge and observation wells indicated the response of the aquifer to the multi cycle recharge recovery process meanwhile a finite difference method fdm numerical model was established and its parameters were obtained via a reversed numerical analysis on the experimental data the responses of the shallow confined aquifer to the multi cycle recharge recovery process were simulated in detail using the model the calculation results showed that the water level dropped significantly when the recharge ended moreover the efficiency of a multi cycle recharge was found to be higher than that of a concentrated one under the same recharge volume and time the relationship between recharge frequency and efficiency expressed as h 0 29498 f 0 40163 and r 2 0 97264 respectively was obtained through the fdm numerical simulation in the recharge intervals the optimal recharge efficiency was achieved when the water level rose to 40 of the peak

dewatering induced subsidence during excavation in a shanghai soft deposit foundation dewatering has become a major cause of land subsidence in shanghai the burial depth of foundations in relation to geotechnical construction works is less than 75 m and the corresponding groundwater includes phreatic low pressure artesian and the first confined aquifers based on the geological and hydrogeological conditions beneath shanghai methods of dewatering may be divided into three modes and further five patterns according to the insertion depth of the dewatering retaining system the most common dewatering mode aims to reduce the water pressure in the confined aquifer by setting the dewatering wells inside the pit whilst the retaining walls are buried in the confined aquifer and partially cut off the confined aquifer layer to predict the settlement due to foundation dewatering numerical models are generally adopted which are similar to those used to predict land subsidence induced by regional groundwater withdrawal however since foundation dewatering is conducted along with the setting of retaining walls and foundation pit excavation which differs from regional groundwater withdrawal interactions between the retaining wall dewatering well the dewatering excavation and dewatering recharge are important factors affecting the analytical model since the grading of the shallow soil layers is different stratified settlement characteristics of the shallow soil strata and seepage erosion which results in additional deformation need to be given particular consideration

an evaluation on h v ratio vs spectral ratio for site response estimation using the 1994 northridge earthquake sequences the applicability of the single station h v method based on the spectral ratio between the horizontal and the vertical components of strong ground motions is examined for site response estimation using the high quality data from the 1994 northridge earthquake sequence instead of using rayleigh wave data from microtremors the large amplitude wave part of the s wave data is used and based on the 1994 northridge mainshock and aftershock recordings we have found that upon averaging over a number of recordings for a given station the station site responses derived both from the single station h v ratio and from the standard spectral ratio with respect to a reference rock site station are sufficiently close for practical purposes we therefore conclude that the h v ratio can reasonably predict the resonant frequency and the amplification level of a site response especially for sites in the neighborhood of the epicenters in the absence of a reference rock site station the h v ratio provides a practical alternative to the standard site response estimation

cryoclastic origin of particles on the surface of enceladus analogous to volcanic deposits on earth we can infer eruption characteristics on enceladus from the relationship between particle size and distance from the vent we develop a model in which ice particles feeding plumes are accelerated by the gas we consider two cases drag limited and collision limited acceleration which link particle size to exit velocity after being ejected at the vent particles follow ballistic trajectories we fit the model to observations of particle size on the surface inferred from modeled vims data collected by the cassini spacecraft we obtain a relationship between gas temperature and characteristic acceleration length whereby lower gas temperatures require longer acceleration lengths the model shows that the large size of particles on the surface is consistent with the size of particles observed with the cda and vims instruments at heights of cassini flybys and the size of particles that reach escape velocity and are found in saturn s e ring

landslides associated with spheroidally weathered mantle of granite porphyry induced by 2011 typhoon talas in the kii peninsula japan abstract typhoon talas brought heavy rain to the kii peninsula japan during 2 5 september 2011 causing hundreds of debris avalanches and debris flows in the southeastern part of the peninsula we undertook field investigations to understand the geological and geomorphological context of the landslides and found that the most important geological factor is spheroidal weathering of granite porphyry this granite porphyry is deeply weathered with corestones in higher elevations and forms low relief surfaces of which marginal areas were the major sources of debris avalanches corestones that failed were embedded in grus in situ or on nearby slopes of mudstone in which the granite porphyry intruded the corestones are made by spheroidal weathering from well developed columnar joints and sheeting joints sheeting joints in the source granite porphyry acted as sliding surfaces both before and during the occurrence of the 2011 debris avalanches

engineering and geological characteristics of granite weathering profiles in south china granite weathering profiles are widely distributed in south china their engineering and geological characteristics are major geotechnical subjects that are important in the design and construction of civil engineering projects this paper presents a summary of the weathering characteristics and zoning of granite weathering profiles in south china and discusses their engineering and geological properties a five grade scheme has been adopted in the zoning of a granite weathering profile studies have shown that the completely weathered granites cwg in south china have the following characteristics low moisture content low to medium plasticity w l 22 5 39 0 i p 6 5 11 8 medium void ratio 0 36 1 29 weak shrinkage and medium compressibility a 1 2 0 24 0 8 mpa 1 and high shear strength phi 20 30degrees c 20 40 kpa the cwgs are usually at a low or high plastic state and most of them are over consolidated soils a majority of the physical and mechanical properties have good statistical correlations with the degree of weathering the data presented in the paper are important in geotechnical engineering projects such as slope stability evaluation in china c 2002 elsevier science ltd all rights reserved

analysis of spectral ratios for estimating ground motion in deep basins abstract use of nakamura9s spectral ratio horizontal versus vertical components is investigated theoretically for deep sedimentary basins by considering semi circular and semi spherical valleys the ratio is evaluated from the steady state surface response for different incident waves based on this ratio both the resonant frequencies and ground motion amplification are determined the results based on nakamura9s ratio are compared with those based on the sediment to bedrock spectral ratios kagami9s ratio the results show that for both two and three dimensional models nakamura9s technique predicts well the fundamental resonant frequency but it could not determine higher resonant frequencies of the basins the error in nakamura9s estimate of the fundamental resonant frequency increases for stations near the valley center for alluvial valleys considered in this article nakamura9s ratio failed to predict accurately surface ground motion amplification

on the horizontal to vertical spectral ratio in sedimentary basins the horizontal to vertical spectral ratio hvsr has been used by many researchers to characterize local conditions in terms of the dynamic response of the soil one of its variants is that proposed by nakamura 1989 in which records of microtremors are used usually the analysis is aimed to obtain the predominant period of the site under study in this work we explore what can be achieved by using this method we study the response of different configurations under incident waves coming from an explosive source using the indirect boundary element method ibem we investigate two cases low and high velocity contrast holding constant the physical properties inside the basin and changing only the properties of the bedrock then we compute the seismic response using the horizontal sediment to bedrock spectral ratio sbsr at various locations on the free surface of the basins and compare it with the one calculated by the hvsr at the same locations the comparison shows that in general the predominant period computed with the hvsr is not the same as that obtained by the sbsr in all the locations on the other hand the hvsr approximation can reasonably well predict the fundamental local frequencies when the impedance contrast between the basin and the bedrock is low however hvsr cannot be used in sedimentary basins having a high impedance contrast with respect to the bedrock below

the composition and structure of enceladus plume from the complete set of cassini uvis occultation observations abstract observations acquired at ultraviolet wavelengths are uniquely well suited to investigate the composition and structure of enceladus plume this paper describes the observations analysis techniques and results of all the enceladus occultations observed by cassini s ultraviolet imaging spectrograph uvis and other observations designed to study the plume limits on gas at non polar latitudes are derived constraints on the minor constituents composition of enceladus primarily water vapor plume are evaluated the overall source rate variability over a time span of 13 years is

the height of fractured water conducting zone in undermined rock strata the height of fractured water conducting zone is of significant importance for the safety of underground mining because of the conspicuous discrepancy of the height of fractured water conducting zone in bulianta coal mine as predicted by the traditional method with those observed in practice a systematic research has been carried out the study indicates that two aspects should be taken into account firstly the traditionally proposed empirical formula in prediction of the height of fractured zone was based on the conditions of single slice mining where the mining height was less than 3 m and the total slice mining height was limited within 15 m in such a case it would not be suitable to predict the maximum fractured zone height for the conditions where a single mining height is larger than 3 m secondly the stratum structure such as the thick and strong rock layer termed as key stratum plays an important role in controlling of the height of movement in the overburden physical model tests by making use of a similar material illustrate that if the vertical distance from the primary key stratum to the coal seam is shorter than a certain value then the developing fracture zone will extend above the key stratum into the top of bedrock resulting in a larger height of water conducting zone than is calculated by the empirical method the outcome of the work presented will be helpful in practice to prevent the overburden aquifer inrush and to avoid mine water hazard

influence of structure and water pressure on the hydraulic conductivity of the rock mass around underground excavations abstract in this study in situ water injection tests and numerical modeling in conjunction with core logs and television image measurements were applied for an investigation of the hydraulic properties of the rock mass around underground excavations the aim of our work was to investigate the influence of rock structure and water pressure on the hydraulic conductivity of the rock mass around underground excavations thus water injection tests were conducted in four boreholes that were drilled in the rock mass in underground tunnels in china seepage connection initiation and steady state seepage were proposed to identify the seepage evolution course within the rock mass by combining the results of pressure and hydraulic conductivity generally hydraulic conductivity is strongly related to rock structure and water pressure the results also revealed that a rearrangement of rock structure would occur in the damage zone resulting in an increase in hydraulic conductivity of nearly one to several orders of magnitude the results from the modified numerical model showed that the pore water distribution and the groundwater inflow rate are affected by both the hydraulic conductivity and the thickness of the damage zone and they are influenced more by the thickness of this zone

groundwater as an environmental constraint of longwall coal mining groundwater impacts are a common reason for opposition to longwall mining most impacts are due to subsidence related fracturing although upper aquifers are protected from drainage to the mine by a confining zone water levels decline due to fracture dilation and drawdown expands outward a few hundred meters recovery of water levels is common

evaluation of the blocking effect of retaining walls on groundwater seepage in aquifers with different insertion depths abstract in the design of a deep retaining wall it is necessary to consider the blocking effect on groundwater seepage of retaining walls in aquifers in this study both laboratory tests and numerical simulation with finite element method fem were adopted to investigate the blocking effect on groundwater seepage under different insertion depths of retaining wall in aquifer laboratory tests were conducted to analyze this blocking effect in an unconfined aquifer the test results indicate that the effective insertion depth ratio j of a retaining wall in shanghai aquifer sand is about 70 a three dimensional numerical model 3d fem was conducted to analyze the laboratory test results the fem results show that fem is a reliable method to analyze the blocking effect on groundwater seepage in an aquifer based on the same aforementioned procedure a 3d fem model is established to investigate the blocking effect in the confined aquifer in shanghai deposit both laboratory test and fem results show that drawdown of groundwater level decreases with an increase of the insertion depth ratio j of retaining structures in an aquifer the optimal value of j approximately 70 is achieved for retaining wall based on the synthetic results from laboratory test fem analysis and the equation of pujades et al for either unconfined aquifers or confined aquifers of shanghai

characteristics of ice grains in the enceladus plume from cassini observations ice grains in the enceladus plume have been observed by several cassini instruments during many enceladus encounters in this paper we study the ice grains ranging from less than one nanometer to micrometers in size based on multiple instrument observations we have analyzed the nanograin data from the e17 and e18 cassini plasma spectrometer caps energy spectra using the approach of hill et al 2012 and studied the charging of the grains using the e3 e6 radio and plasma wave spectrometer rpws langmuir probe lp data presented by morooka et al 2011 to bridge the gap between caps nanograin observations and cosmic dust analyzer and rpws micrograin observations we propose a composite size distribution and fit it to the e3 e5 e17 and e18 caps and rpws data the resulting size distribution peaks at 2 nm and provides a total grain mass density 20 that of the water vapor measured by ion and neutral mass spectrometer at the densest part of the plume and a total grain charge density much smaller than that inferred from the rpws lp plasma data charge balance with the rpws lp plasma data would require many more grains than provided by the best fit composite distribution to the caps and rpws data and would provide a grain mass density comparable to that of the water vapor on the basis of these results we study the subsequent motion of the ice grains and estimate the resulting grain current 104 to 105a and grain mass production rate 15 65 kg s

statistical and hydro mechanical coupling analyses on groundwater drawdown and soil deformation caused by dewatering in a multi aquifer aquitard system abstract groundwater withdrawn in a multi aquifer aquitard system maas may cause vertical cross flow supplement and result in groundwater drawdown and soil deformation in both aquifers and aquitards this study investigates the responses of groundwater and deep soils to dewatering in the maas through statistical and numerical analyses field data of ten pumping tests conducted in the maas in shanghai urban area are collected and a statistical analysis for groundwater drawdown and ground settlement is performed field measurements indicate that the drawdowns are distributed linearly along radial distance in logarithmic coordinates however the ground settlements are disproportional to the drawdowns and show a trilinear distribution along the radial direction to examine the inconsistent distributions of the groundwater drawdown and the ground settlement representative dewatering models are developed numerically and solved explicitly by the coupled biot s three dimensional consolidation theory numerical results of dewatering in maas are compared to those obtained by a non coupling formula moreover effect of a micro confined aquifer on drawdown and soil deformation is discussed it is found that soil compression in each stratum is closely related to the decline of the pore pressure whilst small expansions are observed in early dewatering stages due to the hydro mechanical coupling effect the ground surface settlement near the pumping well obtained by the coupled numerical method is significantly smaller than that by the non coupling formula owing to horizontal and vertical cross flow supplement an additional aquifer embedded in aquitard above the pumping aquifer can relief both the groundwater drawdown and ground surface settlement significantly

effects of hydrothermal alterations on physical and mechanical properties of rocks in the kuril kamchatka island arc abstract the hydrothermal systems of the kuril kamchatka island arc are hosted in volcanic formations of neogene quaternary age thermal water alters volcanic rocks and transforms them into hydrothermal rocks such as secondary quartzites various propylites zeolitic rocks argillic rocks clays opalites and quartz feldspar metasomatites mineralogical alteration of rocks contributes to changes of their physical and mechanical properties the relationship between type of hydrothermal alteration and rock properties is quite variable and depends on a number of factors including parent rocks conditions chemical composition and type of fluid and duration of fluid rock interaction the study showed that high temperature fluids cause consolidation and strengthening of rock decrease in their porosity and permeability and remove hygroscopic moisture this tendency is observed independently of fluid chemical composition property variations caused by low temperature subsurface fluids are more complicated and diverse but their deterioration prevails i e a decrease in density strength and elastic modulus formation of secondary porosity high hygroscopy softening and swelling in water saturated environment special attention is given to the near surface alteration zones which affects the selection of sites for power plant construction and can impact the integrity of their foundation the subsurface horizon of hydrothermal clays is the most problematic zone due to high porosity plasticity hygroscopy compressibility and occasionally swelling

earthquake site response study in giumri formerly leninakan armenia using ambient noise observations we have tested whether ambient noise observations reveal useful information regarding site response at sediment sites in giumri formerly leninakan armenia this was done by comparing the noise observations with spectral ratio site response estimates based on aftershock data of the 7 december 1988 earthquake we show that neither the horizontal component noise spectra alone nor spectral ratios taken with respect to a nearby bedrock site reveal useful information regarding site response however spectral ratios of horizontal components taken with respect to vertical components nakamura s method exhibit a prominent peak that corresponds to the fundamental resonant frequency observed in the aftershock data based on this and other recent investigations we conclude that nakamura s method may be a reliable procedure for determining the fundamental resonant frequency of sedimentary deposits from ambient noise observations

responses of retaining wall and surrounding ground to pre excavation dewatering in an alternated multi aquifer aquitard system abstract pre excavation dewatering ped is an important construction stage in deep excavation field measurements show that retaining walls can develop obvious deflections during ped which has been rarely considered in the past the characteristics of ped induced wall deflection and the relationship of this deflection to surrounding ground deformation are still unclear in this study a ped test is simulated by a numerical model the model is verified by field observations and used to investigate the responses of retaining wall and surrounding ground to ped results indicate that the maximum wall defection hm and surface settlement vm can all reach centimeter level under common conditions of ped the ratio of vm to hm varies at the range of 0 45 0 67 wall and soil deformations will be more obvious if the soils within the dewatering depth hd have better permeability the relative positions between hd and strata i e aquifer or aquitard have great influence on the ped induced deformations if an aquifer appears below hd further increasing hd can induce a rapid growth of wall and soil deformations if thick aquitard appears below hd the deformation increments by further increasing hd are not apparent however once hd exceeds the center of the thick aquitard and reaches a thick confined aquifer the wall deflections and soil deformation zones behind the wall will enlarge significantly meanwhile a large bending moment in the retaining wall will arise around the bottom of the confined aquifer the designers should consider this condition and allocate enough steel rebars there preventing the appearance of wall cracks in the confined aquifer

the miarolitic pegmatites from the konigshain a contribution to understanding the genesis of pegmatites in this paper we show that the crystallization of miarolitic pegmatites at konigshain started at about 700 c in melts containing up to 30 mass water such high water concentration at low pressures 1 3 kbar is only possible if the melts are peralkaline such peralkaline melts are highly corrosive and reacted with the wall rock here the granite host forming the graphic granite zone in part via a magmatic metasomatic reaction with cooling the water concentration in some melt fractions increased up to 50 mass h2o the melt dominated system ends below 600 c and passes into a fluid dominated system the beginning of which is characterized by strong pressure fluctuations caused by the change of oh and co32 in the melt to molecular water and co2 we note two generations of smoky quartz one crystallized above the transition of quartz 573 c and one below both of which contain melt inclusions this indicates that some melt fraction remains during at least the higher temperature portion of the growth of minerals into the miarolitic cavity contradicting the view that minerals growing into a pegmatite chamber only do so from aqueous fluids we show that the konigshain miarolitic pegmatites are part of the broad spectrum of pegmatite types and the processes active at konigshain are representative of processes found in most granitic pegmatites and are thus instructive in the understanding of pegmatite formation in general and constraining the composition and characteristics of pegmatite forming melts

countermeasures of water and mud inrush disaster in completely weathered granite tunnels a case study this paper presents a case study of the countermeasures of water and mud inrush disasters in the junchang tunnel in guangxi china this tunnel was constructed in a weathered granite formation and four serious water and mud inrush disasters occurred during construction the geological and hydrological conditions are first reviewed to understand their effects on the water and mud inrush disasters four potential causes of the serious water and mud inrush disasters in the junchang tunnel were proposed including the poor stability of the completely weathered granite the high groundwater level and large groundwater flow rate insufficient pre reinforcement of the surrounding rock and the disturbances caused by tunnel construction water sealing and ground reinforcement measures were suggested before excavation to improve the stability of the surrounding rock and plug the water outflow channels and full face curtain grouting was considered as the first choice furthermore several improvements including the combined utilization of various grouting materials supplementary grouting with steel pipes in collapsed boreholes and dynamically optimized grouting methods were implemented to solve the serious water inflow and collapse problems experienced during the drilling and grouting work a detailed curtain grouting scheme was proposed and applied in practice a comprehensive evaluation based on inspection borehole investigations and p q t analysis indicated that the curtain grouting method yielded satisfactory performance in water sealing and ground reinforcement in addition the groundwater level and settlement data collected in the field validated the effectiveness of the proposed countermeasures

numerical study on the responses of groundwater and strata to pumping and recharge in a deep confined aquifer abstract groundwater drawdown and strata settlements induced by dewatering in confined aquifers can be relieved by artificial recharge in this study numerical simulations of a field multi well pumping recharge test in a deep confined aquifer are conducted to analyze the responses of groundwater and strata to pumping and recharge a three dimensional numerical model is developed in a finite difference software which considers the fluid mechanical interaction using the biot consolidation theory the predicted groundwater drawdown and ground settlements are compared to the measured data to confirm the validation of the numerical analysis of the pumping and recharge both numerical results and measured data indicate that the effect of recharge on controlling the groundwater drawdown and strata settlements correlates with the injection rate and well arrangements since the groundwater drawdown induced by pumping can be controlled by artificial recharge soil compression can be relieved by reducing the changes of effective stress of the soils consequently strata settlement induced by pumping can be relieved by artificial recharge and ground settlements can be eliminated if an appropriate injection rate and well arrangement are being determined moreover the changes of the pore pressure and seepage force induced by pumping and recharge will also result in significant horizontal deformations in the strata near the recharge wells

analyses of leakage effect of waterproof curtain during excavation dewatering abstract the waterproof curtain that is used to block groundwater leaks occasionally during deep excavation and can have a harmful impact on the surroundings this study adopts a three dimensional 3d fluid solid coupled finite element model fem to analyze the impact due to a leakage in the waterproof curtain during excavation dewatering in the model both a user defined one dimensional leakage element and a solid leakage element are incorporated to simulate the leakage the leakage of the curtain in the soil is analysed by monitoring the variation in hydraulic conductivity the simulated results demonstrate that the leaking rate leaking volume groundwater drawdown and ground settlement are closely related to the hydraulic conductivity of the leakage point the results also show that the groundwater head outside the pit declines quickly when the leakage occurs but soil consolidation proceeds slowly in addition the characteristics of the soil that is adjacent to the leakage point also have a tangible effect on the groundwater head and ground settlement the hydraulic conductivity and deformation modulus of the soil has a significant effect on the ground settlement while the influence of the anisotropy of the soil is relatively low

distribution of icy particles across enceladus surface as derived from cassini vims measurements abstract the surface of enceladus consists almost completely of water ice as the band depths of water ice absorptions are sensitive to the size of particles absorptions can be used to map variations of icy particles across the surface the visual and infrared mapping spectrometer vims observed enceladus with a high spatial resolution during three cassini flybys in 2005 orbits en 003 en 004 and en 011 based on these data we measured the band depths of water ice absorptions at 1 04 1 25 1 5 and 2 m these band depths were compared to water ice models that represent theoretically calculated reflectance spectra for a range of particle diameters between 2 m and 1 mm the agreement between the experimental vims and model values supports the assumption that pure water ice characterizes the surface of enceladus and therefore that variations in band depth correspond to variations in water ice particle diameters our measurements show that the particle diameter of water ice increases toward younger tectonically altered surface units with the largest particles exposed in relatively fresh surface material the smallest particles were generally found in old densely cratered terrains the largest particles 0 2 mm are concentrated in the so called tiger stripes at the south pole in general the particle diameters are strongly correlated with geologic features and surface ages indicating a stratigraphic evolution of the surface that is caused by cryovolcanic resurfacing and impact gardening

hard rock spectral models for intermediate depth vrancea romania earthquakes the frequency dependent amplification for rock sites as well as apparent source spectra were studied using an earthquake ground motion database collected in romania almost all events occurred in the vrancea focal zone southeast carpathians which is characterized by a high rate of occurrence of large earthquakes in a narrow focal volume the seismic activity ranges within an almost vertical stripe in depths between 60 and 170 km the database used includes several hundred records from more than 100 small magnitude m w 3 5 5 3 earthquakes that occurred in 1996 2004 and six acceleration records obtained during four large m w 7 2 6 9 6 3 and 6 0 earthquakes the characteristics of amplification were evaluated using the well known technique of horizontal to vertical h v fourier spectral ratio of the s wave phase lermo and chavez garcia 1993 the apparent source spectra were obtained from horizontal components using site h v propagation path geometric spreading and anelastic attenuation and near surface attenuation kappa factor corrections seismic radiation within the frequency range from 0 2 0 3 to 15 20 hz during the earthquakes of various magnitudes in the vrancea zone may be described by an omega square single corner frequency spectral model 2 brune spectrum the stress parameter which controls high frequency spectral amplitudes increases with magnitude from 20 30 bars for m w 3 5 up to 200 250 bars for m w 4 8 5 3 and up to 1000 bars for the case of large m w 6 0 6 5 events empirical amplification h v for rock sites showing stability for particular locations reveal high variability from station to station which together with variations of values of kappa reflects influence of local geologic and geomorphologic factors

reconciliation of crosshole seismic velocities with well information in a layered sedimentary environment in sedimentary environments horizontal fine layering can cause significant complications when analyzing and comparing seismic data with different frequencies and propagation directions at the whitchester test site three boreholes penetrate upper carboniferous cyclical sediments involving interbedded carbonates sandstones and mudstones with seismic velocities ranging from less than 3 0 km s in the mudstones to over 4 5 km s in the carbonates initial crosshole results from two boreholes approximately 200 m deep and 75 m apart showed a poor correlation with the borehole logs recorded in a third intermediate borehole furthermore the tomographic images were inconsistent with the expected geology the objective of this paper is to reconcile the crosshole seismic data with the borehole log information the borehole information must be upscaled to match the resolution of the crosshole experiment however upscaling techniques based on backus averaging lead to the prediction of significant anisotropy of the order of 20 in places with a vertical symmetry axis this anisotropy is a result of a combination of fine layering and the intrinsic mineral anisotropy measured on the core samples although it is the layer induced anisotropy that dominates at the crosshole frequencies of 400 hz this prediction was tested by including anisotropy parameters into the analysis of the crosshole data using anisotropic velocity tomography in the central part of the final anisotropic velocity tomograms where the ray coverage is adequate these crosshole results are consistent with the anisotropy predictions once the anisotropy was properly accounted for the tomographic images are consistent with the layered nature of the geology at the site and they show the location and throw of a known fault in the section we conclude that at this site and at crosshole frequencies seismic layer induced anisotropy plays a significant role and must be accounted for when processing and interpreting crosshole seismic data

site response evaluation using the h v ratio at the yan liau station in hualien taiwan four days after the december 13 1990 hualien taiwan earthquake m l 6 9 a temporary array of fifteen triaxial digital accelerographs was deployed in the epicenter area to monitor aftershocks approximately 600 earthquakes triggered this array during the three month deployment period the yan liau station s63 alone recorded 162 events most of the accelerograms at s63 exhibit resonance we have estimated site responses at the yan liau station using both the single station spectral ratio or h v ratio method and the traditional spectral ratio method that compares ratios at a soil site with those at a reference hard rock site based on site response analyses of s waves and coda waves of ground motion recordings both types of waves show that the h v ratio provide a good estimate at the resonant frequency although the site amplification factor is overestimated in addition the study of microtremor is also a good alternate for estimating the site predominant frequency while the ground acceleration or pga gradually increases the resonant frequency shifts to lower frequencies

barrier effect of underground structures on aquifers abstract impervious structures below the water table modify the natural groundwater flow in aquifers they act as barriers causing heads to rise upgradient and to fall downgradient we define the barrier effect as the increase in head loss across the barrier with respect to the natural conditions prior to construction we distinguish between regional the minimum head loss observed at long distances and local the maximum head loss observed close to the structure barrier effects we use numerical and analytical methods to derive semi empirical equations to quantify the two barrier effects for semi permeable partially penetrating or fully penetrating but finite in length and barriers with a by pass in confined aquifers the resulting equations depend on the barrier geometry and on the natural head gradient in the aquifer and they are easy to apply we test their validity at two construction sites obtaining excellent agreement between the computed and observed barrier effects

characteristics of groundwater seepage with cut off wall in gravel aquifer i field observations1 this paper presents a case history of the leakage behavior during dewatering tests in the gravel strata of an excavation pit of a metro station in hangzhou china the groundwater system at the tes

interpretation of increased deformation rate in aquifer iv due to groundwater pumping in shanghai shanghai is a typical example of a region in china suffering from severe land subsidence previous investigations have shown that land subsidence is strongly related to groundwater pumping in both the temporal and spatial domains a series of field investigations shows that the deformation rate of aquifer iv aqiv has increased contributing significantly to the total subsidence in shanghai to predict the deformation behavior of aqiv in shanghai due to groundwater pumping four different models have been applied in this study i a model based on groundwater flow theory ii an elastic model based on cauchy mechanics iii a creep model incorporated into cauchy mechanics and iv a recently proposed land subsidence model by budhu based on cosserat mechanics based on a number of assumptions budhu s concept was extended to consider the time dependent behavior of groundwater potential in aquifers and the consolidation behavior of overburdened aquitards the calculated results of aqiv s deformation we

environmental protection using dewatering technology in a deep confined aquifer beneath a shallow aquifer abstract this paper presents an innovative technology referred to as dual function well dfw which has been developed in order to reduce the construction costs of dewatering when excavation is conducted in an aquitard over a confined aquifer dfw technology is a method to lower both shallow groundwater and deep groundwater either separately or simultaneously using one well the dfw includes two or more independent screens corresponding to each aquifer and a valve is located between the screens inside a steel pipe when the valve is closed groundwater is pumped from the upper screen in the shallow aquifer when the valve is open groundwater is pumped from the screens in both the shallow and deep aquifers dfw technology is used to replace the traditional method involving two sets of wells in which the first set of wells pumps groundwater from the shallow aquifer and a second set pumps groundwater from the deep aquifer to investigate the effectiveness of dfw field pumping tests using a dfw were conducted and both groundwater head and settlement were monitored numerical simulation was adopted to simulate the results of the pumping tests comparison between the results from the dfw and from an ordinary mixing well indicates that the use of a dfw with the valve closed can reduce the pumping time from a deep aquifer and can reduce the ground settlement caused by dewatering the results indicate the dfw technology is feasible and effective

constant head test at a partially penetrating well in an aquifer aquitard system abstract an analytical model for describing pumping induced drawdown by constant head test at a partially penetrating well in a leaky confined aquifer is developed by treating the leakage of aquitard storage as an interface phenomenon rather than an volumetric effect which is the novel and never developed so far three different cases of remote lateral boundaries are considered in the model the new drawdown solution in laplace space is obtained and inverted into time domain solution utilizing the stehfest method the semi analytical solutions for well discharge are then obtained under three different cases analytical solutions in laplace and time domains are developed for calculating the total leakage rate and volume across the aquitard aquifer interface due to constant head test at a partially penetrating well in a leaky confined aquifer and such solutions are of great use for groundwater resource management based on the newly developed solutions the distribution of wellbore flowrate and aquitard leakage are explored and the sensitivity analysis is conducted to identify the most important controlling factor the sensitivity analysis shows that the wellbore flowrate and the drawdown in infinite case 1 finite case 2 and closed case 3 leaky confined aquifer systems are both sensitive to the variation of well partial penetration well radius and aquifer anisotropic ratio during the whole pumping period and they are most sensitive to the change of outer boundary distance at late time for case 3 the effect of the outer boundary on the drawdown or wellbore flowrate is more significant for a shorter outer boundary distance

geological and hydrogeological environment in tianjin with potential geohazards and groundwater control during excavation this paper discusses the geological and hydrogeological features of quaternary deposits in tianjin as well as the geohazards related to groundwater hydrology in this region the soft soil deposits comprising silt sand silty clay and clay are composed of four aquifer groups in the first aquifer group one phreatic aquifer and two confined aquifers have relationships with underground construction in the urban area these three aquifers are separated by two aquitards and collectively form a multi aquifer system during geotechnical construction potential geohazards present are related to the groundwater which include water in rushing quicksand and piping hazards to prevent the aforementioned geohazards dewatering is conducted however groundwater pumping may result in large settlements of the surrounding ground to reduce pumping induced settlement the dewatering waterproofing system has been adopted according to the characteristics of the subsoil excavation depth and the surrounding environment the dewatering system can be divided into five patterns in the first four patterns when pumping is conducted in the excavation pit the groundwater head in the adjacent aquifers outside the pit decreases due to the leakage effect of the aquitards located between the aquifers in the fifth pattern waterproof curtain has cut off the aquifers completely and dewatering in the pit cannot result in settlement around excavation pit to avoid geohazards related to groundwater hydrology countermeasures recommended include construction of an effective waterproof curtain selection of a reasonable excavation dewatering pattern and withdrawal of required groundwater

evaluation of the effectiveness of an alternative to control groundwater inflow during a deep excavation into confined aquifers this paper presents a case study of groundwater control for a deep excavation into confined aquifers in fuzhou china field pumping tests were first carried out prior to the excavation to investigate the groundwater conditions at the site and as well as to evaluate the feasibility of previous designed dewatering systems 34 m diaphragm walls together with pumping wells the results showed that under the condition of previous dewatering systems it would have been extremely difficult to safely lower the water level inside the excavation a co working scenario of partially penetrating curtains and horizontal waterproof curtain with jet grouting was then proposed to control groundwater inflows additional water tightness assessment tests wat were then performed that allowed to confirm the efficiency of the proposed method from the feedbacks of wat this proposed scenario not only successfully lowered the water lever inside the excavation below the excavation bottom maximum drawdown up to 14 9 m but also it minimized the drawdown outside the excavation less than 0 2 m furthermore an approach was proposed to approximately estimate the hydraulic conductivity of the jet grouting at the real site from the result of wat the hydraulic conductivity of jet grouted soil is three orders of magnitude lower than that of the original sediments

curtain eruptions from enceladus south polar terrain observations of the south pole of the saturnian moon enceladus revealed large rifts in the terrain that were found to be the sources of the observed jets of water vapour now it is shown that much of the eruptive activity can be explained by broad curtain like eruptions many of which were probably misinterpreted previously as discrete jets images taken by the cassini probe have revealed large fractures bounded by rifts towards the south pole of saturn s moon enceladus these features popularly known as tiger stripes reach higher temperatures than their surroundings and are thought to be the sources of observed jets of water vapour and icy particles joseph spitale et al compare cassini images with simulated curtains of material erupting from enceladus south polar terrain to produce detailed maps of the emissions at various times much of the eruptive activity can be explained by broad curtain like eruptions many of which were probably misinterpreted previously as discrete jets phantom jets in the synthesized curtains correspond closely to regions of enhanced brightness in the cassini images observations of the south pole of the saturnian moon enceladus revealed large rifts in the south polar terrain informally called tiger stripes named alexandria baghdad cairo and damascus sulci these fractures have been shown to be the sources of the observed jets of water vapour and icy particles1 2 3 4 and to exhibit higher temperatures than the surrounding terrain5 6 subsequent observations have focused on obtaining close up imaging of this region to better characterize these emissions recent work7 examined those newer data sets and used triangulation of discrete jets3 to produce maps of jetting activity at various times here we show that much of the eruptive activity can be explained by broad curtain like eruptions optical illusions in the curtain eruptions resulting from a combination of viewing direction and local fracture geometry produce image features that were probably misinterpreted previously as discrete jets we present maps of the total emission along the fractures rather than just the jet like component for five times during an approximately one year period in 2009 and 2010 an accurate picture of the style timing and spatial distribution of the south polar eruptions is crucial to evaluating theories for the mechanism controlling the eruptions

compaction and seepage properties of crushed limestone particle mixture an experimental investigation for ordovician karst collapse pillar groundwater inrush as mining activity rapidly develops to deeper and deeper ground there have been an increasing number of groundwater inrush events occurring in china the ordovician limestone karst collapse pillar kcp which contains a lot of crushed rocks usually functions as a channel for groundwater inrush the factors such as the geological conditions groundwater flow and extraction percentage of coal seam in underground mines are the main causes of recompaction and permeability change of crushed rock particles in kcp the high permeability of rock will cause large volumes of groundwater flow thus posing a great threat of loss of lives in the mines it is important to take into account the compaction and seepage behaviors of the crushed rocks in ordovician limestone kcp the mts815 02 system and a self designed water flow apparatus were used to investigate the effect of particle size distribution on compaction and seepage behavior of crushed limestone particle mixture the reynolds number calculation of particle mixture shows that the seepage has been influenced by non darcy flow testing results indicate that the effective porosity of crushed limestone sample is strongly influenced by compaction and particle size distribution the effective porosity decreases with the increase in compaction and decrease in larger particle size respectively particle crushing during compaction is a main cause of size 0 2 5 mm materials whereas some fine particles are washed away due to the effect of water seepage which is a main cause of weight loss non darcy seepage properties of the crushed limestone are strongly influenced by compaction and particle size distribution in general during the compaction the permeability decreases while the non darcy coefficient increases with the decreasing of effective porosity the effective porosity particle crushing and seepage properties of crushed limestone are not only related to compaction levels and mixture sizes but also to style of arrangement and initial pore structure

tunnelling through the young himalayas a case history of the maneri uttarkashi power tunnel abstract a 8 56 km long circular tunnel with a finished diameter of 4 75 m has been constructed for the maneri hydel hydro electric project on the river bhagirthi the tunnel passes through quartzitic and metabasic rock formations of the young himalayas the tunnel excavation was accomplished from four headings one from the upstream end at maneri two from an intermediate adit at heena and one from the downstream end near uttarkashi where an 80 mw power house is located problems of tunnel face collapse with or without heavy ingress of water cavity formation and large tunnel closures leading to buckling of steel ribs on account of squeezing ground conditions were encountered methods to combat these problems are described the absence of advance knowledge of the frequently chanigng rock mass and ground water conditions and therefore the inability of the tunnelling engineers to modify the construction method and the support system was responsible for these problems predic values of support pressure obtained from the empirical methods of terzaghi barton et al and the one proposed by singh et al have been compared with the observed values of checking the reliability of various methods particularly for poor rock masses

characterizing deposits emplaced by cryovolcanic plumes on europa abstract in the absence of direct observations of europa s particle plumes deposits left behind during eruptive events would provide the best evidence for recent geological activity and would serve as indicators of the best places to search for ongoing activity on the icy moon here we model the morphological and spectral signatures of europan plume deposits utilizing constraints from recent hubble space telescope observations as model inputs we consider deposits emplaced by plumes that are 1 km to 300 km tall and find that in the time between the galileo mission and the arrival of the europa clipper spacecraft plumes that are

reduction of friction on geological faults by weak phase smearing most common crustal rock types display friction coefficients of 0 6 or higher but some faults must be frictionally weak as they slip when the stress state is unfavourably oriented i e the resolved shear stress is low for a given normal stress across the fault surface a role for low friction minerals and high pore fluid pressures either separately or in combination is frequently invoked to explain such slip but volume fractions of dispersed weak phases often seem to be present in fault gouge in amounts too small to produce significant mechanical weakening by means of mechanical tests on synthetic fault gouge and microstructural study of run products we show that the effective area of an embedded weak phase graphite on a slip plane can be substantially increased by mechanical smearing and that the enlarged area of the weak phase on the slip plane follows a linear mixing law this allows a relatively small volume fraction of the initially dispersed weak phase to have a disproportionately large effect provided the smearing is concentrated into a narrow planar slip zone or into an interconnected network of them

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

pumping tests in non uniform aquifers the linear strip case abstract many pumping tests are performed in geologic settings that can be conceptualized as a linear infinite strip of one material embedded in a matrix of differing flow properties a semi analytical solution is presented to aid the analysis of drawdown data obtained from pumping tests performed in settings that can be represented by such a conceptual model integral transform techniques are employed to obtain a solution in transform space that can be numerically inverted to real space examination of the numerically transformed solution reveals several interesting features of flow in this configuration if the transmissivity of the strip is much higher than that of the matrix linear and bilinear flow are the primary flow regimes during a pumping test if the contrast between matrix and strip properties is not as extreme then radial flow should be the primary flow mechanism sensitivity analysis is employed to develop insight into the controls on drawdown in this conceptual model and to demonstrate the importance of temporal and spatial placement of observations changes in drawdown are sensitive to the transmissivity of the strip for a limited time duration after that time only the total drawdown remains a function of strip transmissivity in the case of storativity both the total drawdown and changes in drawdown are sensitive to the storativity of the strip for a time of quite limited duration after that time essentially no information can be gained about the storage properties of the strip from drawdown data an example analysis is performed using data previously presented in the literature to demonstrate the viability of the semi analytical solution and to illustrate a general procedure for analysis of drawdown data in complex geologic settings this example reinforces the importance of observation well placement and the time of data collection in constraining parameter correlation a major source of the uncertainty that arises in the parameter estimation procedure

evaluation of optimized depth of waterproof curtain to mitigate negative impacts during dewatering abstract dewatering using a combination of waterproof curtain and pumping wells is commonly adopted to ensure the stability of foundation pits in multi aquifer strata however dewatering is likely to result in environmental problems this paper investigates the impact on surroundings owing to the interaction between the waterproof curtain and pumping wells by numerical simulation the depth of the diaphragm wall penetrating the dewatering aquifer d and the filter length of pumping wells l are varied in the simulation the relationship between approximate hydraulic gradient i or ground settlement outside the foundation pit s with curtain depth ratio rd d over the thickness of the dewatering confined aquifer ha or filter length ratio rl l ha can be divided into three change parts namely initial gradual middle sharp and final gentle part three values of rd and rl namely effective suggested and control value are proposed rd and rl should vary between the effective and control value the suggested value of rd and rl is recommended in actual engineering by comprehensive consideration the effective suggested and control value of rd can be calculated by a linear equation according to the value of rl

microtremor survey in talchir india to ascertain its basin characteristics in terms of predominant frequency by nakamura s ratio technique abstract the talchir basin one of india s oldest basins has been a subject of interest because of its rich coal deposits the maximum thickness of the basin is about 1500 m beyond the basin is the hard metamorphic rocks of precambrian age the ambient noise survey data have been analyzed for the talchir basin using nakamura s technique of horizontal vertical spectral ratio hvsr to ascertain the basin structure in terms of the predominant frequency the predominant frequency varies from 0 25 hz to 7 8 hz but a major portion of the basin comes under the range of 0 3 hz 2 4 hz while on the metamorphic rocks it is as high as 7 8 hz the variation in predominant frequency shows a good correlation with the sediment thickness of the basin the results have been compared with the previous studies by other researchers and it shows consistency with the northerly dip of the basin the present study has also been compared with the results of the synthetic seismogram that was performed for the talchir basin the predominant frequency obtained from hvsr technique complements well with the frequency at which the peak response spectra ratio is observed the present study of the predominant frequency identifies quite well the characteristics of talchir basin and is in good agreement with the synthetic ground motion modeling of the region

cassini observes the active south pole of enceladus cassini has identified a geologically active province at the south pole of saturn s moon enceladus in images acquired by the imaging science subsystem iss this region is circumscribed by a chain of folded ridges and troughs at 55 s latitude the terrain southward of this boundary is distinguished by its albedo and color contrasts elevated temperatures extreme geologic youth and narrow tectonic rifts that exhibit coarse grained ice and coincide with the hottest temperatures measured in the region jets of fine icy particles that supply saturn s e ring emanate from this province carried aloft by water vapor probably venting from subsurface reservoirs of liquid water the shape of enceladus suggests a possible intense heating epoch in the past by capture into a 1 4 secondary spin orbit resonance

dewatering of a deep excavation undertaken in a layered soil in order to carry out deep excavations under the water table in urban environments the safety of the work site and of the adjacent buildings is a major cause for concern one of the most common and effective methods of undertaking these excavations involves combining the cut and cover method with a dewatering system the success of a construction depends on the stability of the excavation bottom the effects produced outside the excavation by dewatering soil movements and or the state of the enclosure defects in the diaphragm walls this study proposes a realistic multidisciplinary procedure to address these issues the work emphasizes the importance of soil characterisation and underlines the need to perform a watertightness assessment test wtat before the excavation stage the procedure was applied to the excavation of a deep shaft of the high speed train hst tunnel in barcelona an earlier geological characterisation at large scale ruled out the use of deep pumping wells however a subsequent hydrogeological characterisation which involved borehole logging grain size analyses natural gamma ray and pumping tests revealed the presence of thin transmissive layers inside the low hydraulic conductivity materials the dewatering system was designed by considering different model scenarios and the safest design was selected for the excavation depths of the enclosure and of the pumping wells differed in accordance with the scenarios the impacts settlements due to pumping and the stability in each scenario were computed the state of the enclosure underwent a wtat before the start of the excavation but after constructing the enclosure to verify its low permeability the test consisted in pumping inside the enclosure and monitoring the groundwater behaviour outside the enclosure numerical interpretation of this test showed a defect in the diaphragm walls below the excavation bottom since this defect was not repaired because of its location below the bottom of the excavation the dewatering system had to be redesigned to ensure safety surface settlements which were also a source of concern were small they were computed using coupled hydro mechanical models

mesozoic tectonic evolution of the southeast china block new insights from basin analysis abstract in order to better understand the mesozoic tectonic evolution of southeast china block secb in short this paper describes geological features of mesozoic basins that are widely distributed in the secb the analyzed data are derived from a regional geological investigation on various mesozoic basins and a recently compiled 1 1 500 000 geological map of mesozoic cenozoic basins two types of basin are distinguished according to their tectonic settings namely the post orogenic basin type i and the intracontinental extensional basin type ii the latter includes the graben and the half graben or faulted depression basins our studies suggest that the formation of these basins connects with the evolution of geotectonics of the secb the post orogenic basin type i was formed in areas from the piedmont to the intraland during the interval from late triassic to early jurassic and the formation of the intracontinental extensional basin type ii connects with an intracontinental crustal thinning setting in the late mesozoic the graben basin was generated during the middle jurassic and is associated with a bimodal volcanic eruption and the half graben or faulted depression basin filled mainly by the rhyolite tuff and sedimentary rocks during early cretaceous is occupied by the late cretaceous paleogene red colored terrestrial clastic rocks we noticed that the modern outcrops of numerous granites and basins occur in a similar level and the mesozoic granitic bodies contact with the adjacent basins by large normal faults suggesting that the modern landforms between granites and basins were yielded by the late crustal movement the modern basin and range framework was settled down in the cretaceous abundant sedimentary structures are found in the various basins from that the deposited environments and paleo currents are concluded during the late triassic early jurassic time the source areas were situated to the north and northeast sides of the outcrop region in this paper we present the study results on one geological and geographical separating unit and two separating fault zones the wuyi orogenic belt is a late mesozoic paleo geographically separating unit the ganjiang fault zone behaves as the western boundary of early cretaceous volcanic rocks and the zhenghe dapu fault zone separates the se china coastal late mesozoic volcanic sedimentary basins and the wuyi orogenic belt finally we discuss the geodynamic mechanisms forming various basins proposing a three stage model of the mesozoic sedimentary evolution

alteration characteristics of granite contact zone and treatment measures for inrush hazards during tunnel construction a case study abstract several large scale mud and water inrush events occurred during excavation of the denghuazhai tunnel at a depth of 175 m in the contact zone between geodic granite and tuff by analyzing the inrush process the characteristics of the inrush hazards such as high pressure abundant water high mud and sand content and strong destructive power were revealed in addition the inrush hazards were intermittent uncertain and sudden an intrusive contact zone between geodic granite and tuff was revealed by regional geological investigation large scale alteration occurred both in geodic granite and tuff near the contact zone petrographic analyses indicated that alteration to albite sericite and kaolinite occurred in geodic granite and alteration to quartz and montmorillonite took place in tuff gradually toward the contact zone furthermore the changes were gradational within and between various alteration grades the closer to the contact zone the higher degree of alteration the less the primary minerals including quartz k feldspar and plagioclase the more the secondary minerals such as sericite and clay minerals tests on porosity saturated water content and uniaxial compressive strength indicated that alteration led to significant deterioration of physical and mechanical properties of rocks except for silicified tuff especially for the zonal clay in the central area of contact zone the physical and mechanical properties were poor and obvious swelling disintegration and argillation were observed tunnel excavation triggered swelling disintegration and argillation of clay leading to several large scale inrush events in terms of treatment of inrush hazards first of all a comprehensive exploration method based on petrographic analyses geophysical detection and borehole drilling was established according to the alteration characteristics so as to identify the scale and composition of the altered zone the principle of consolidation before removal was adopted to deal with the inrush deposits for breach sealing and reinforcement energy release and stress reduction during tunnel construction and regular drainage during operation were achieved by dewatering measures namely drainage supplemented by sealing water drainage and solids remaining reinforcement measures including full face curtain grouting and double layer pipe sheds were adopted to reinforce and seal the highly disturbed rock and soil in advance finally technical measures including bench excavation enhancement of support stiffness and timely installation of secondary support were employed to effectively prevent large deformation in disturbed rock masses with the above measures the left and right tunnels of the denghuozhai tunnel have passed through the altered zone successfully

time variability of the enceladus plumes orbital periods decadal periods and aperiodic change the enceladus plumes vary on a number of timescales tidal stresses as enceladus revolves in its eccentric orbit lead to a periodic diurnal variation in the mass and velocity of solid particles in the plume tidal stresses associated with an orbital resonance with dione lead to a periodic decadal variation aperiodic variations occur on time scales of months and may be due to ice buildup and flow of the walls of the fissures that connect the ocean to the surface we document these variations using all the relevant data taken by the iss instrument from 2005 to 2017 key questions now include how a 5 peak to peak variation in orbital eccentricity which itself is only 0 0045 could lead to a 2 fold decadal variation in plume properties another question is how the plumes stay open if ice builds up every month and clogs the vents other questions include why the solid particles exit the vents several times slower than the gas and why the speeds vary inversely with the mass of the plumes the cassini data are in but the modeling has just begun

study on the failure mechanism of clay layer overlying thin bedrock in coal seam mining the water blocking property of clay at the bottom of the cenozoic overburden is an important factor for mining safety and protecting underground latent water resources in thin bedrock coal seam mining the failure mechanism of such a clay is studied based on the actual engineering background of the sanyuan coal mine the failure of the overlying clay layer is due to the reduction in the supporting space of the clay layer with the progression of coal mining and the overlying clay layer will subside due to the self weight load therefore the vertical stress horizontal stress and shear stress of the soil change during subsidence and the change in these stresses determine whether the clay layer fails then the failure criterion of soil expressed by the vertical stress horizontal stress and shear stress is derived based on mohr coulomb shear failure theory next the function relating the stress and subsidence magnitudes are established by fit analysis finally a failure criterion expressed in terms of soil subsidence amount is presented based on the failure criterion expressed by soil subsidence amount a method for soil failure discriminant is proposed in which only the subsidence amount is necessary to judge the soil failure state this method is applied to the engineering of the sanyuan coal mine to get the failure subsidence amount curve of clay layer i the results show that the failure subsidence amount curve plots below the subsidence amount curves of clay layer i at any advancing distance that is the clay layer did not fail an investigation of the source and amount of water inflow to the 3301 working face also verifies that the clay layer does not fail and the failure discriminant method used to judge the failure state of the soil is appropriate and convenient for use in engineering applications

grain size and depositional environment as predictors of permeability in coastal marine sands more than half of the surface sediments covering the continental shelves are sandy which may permit substantial sub seafloor pore water advection knowledge of sediment permeability is required for quantifying advection and associated solute transport but studies of marine sediments typically report grain size analyses rather than permeability here data from 23 studies were examined to determine the range in permeabilities reported for sublittoral marine sands and to assess the utility of permeability grain size relationships in this setting in the resulting database the permeability of small w30 cm undisturbed cores collected from the sea floor all fell between 2 10 12 and 4 10 10 m 2 a range where advective transport induced by wave and current action should be pervasive the range in grain size was very similar for near shore 10 m water depth but the permeability of the continental shelf samples was consistently lower for the same median grain size empirical permeability grain size relationships generated a poor fit r 2 0 35 for the aggregate data but separate relationships for near shore and continental shelf samples were significantly better r 2 0 66 and 0 77 respectively permeability grain size relationships thus may be useful for sublittoral sands but a larger database needs to be accumulated before reliable fit parameters and variability can be predicted thus it is recommended that permeability be routinely determined when characterizing sedimentological properties of marine sand deposits concurrent determinations of sediment bulk density and porosity may further improve estimates of permeability 2008 published by elsevier ltd

site effect evaluation using spectral ratios with only one station the spectral ratio technique is a common useful way to estimate empirical transfer function to evaluate site effects in regions of moderate to high seismicity the purpose of this paper is to show that it is possible to estimate empirical transfer function using spectral ratios between horizontal and vertical components of motion without a reference station the technique originally proposed by nakamura to analyze rayleigh waves in the microtremor records is presented briefly and it is discussed why it may be applicable to study the intense s wave part in earthquake records results are presented for three different cities in mexico oaxaca oax acapulco gro and mexico city these cities are very different by their geological and tectonic contexts and also by the very different epicentral distances to the main seismogenic zones affecting each city each time we compare the results of nakamura s technique with standard spectral ratios in all three cases the results are very encouraging we conclude that if site effects are caused by simple geology a first estimate of dominant period and local amplification level can be obtained using records of only one station

characteristics of groundwater seepage with cut off wall in gravel aquifer ii numerical analysis this paper presents a numerical investigation into the leakage behavior of cut off walls in gravel strata due to dewatering in a deep excavation pit the calculated values of the groundwater head and surface settlement using a model agree well with the measured values values of the hydraulic conductivity k and storage coefficient ss of each soil layer are obtained from the test results when the cut off wall is 43 m deep the leakage through the cut off wall in gravel is analyzed by considering a variation in hydraulic conductivity in different sections of the cut off wall the simulated results show that a significant leakage occurred in the 54 m deep cut off wall although leakage did occur in the full cut off wall in the confined aquifer the full cut off wall is still more efficient in preventing groundwater seepage than the partial cut off wall the relative depths of the cut off wall and of the wells have a significant effect on ground surface settlement during the withdrawal of groundwater the

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

mineralogical and geochemical characteristics of hydrothermal alteration and episyenitization in the konigshain granites northern bohemian massif germany the late hercynian granites of konigshain underwent multistage hydrothermal processes extensive high temperature late magmatic alteration is for example indicated by low zr hf and an ree pattern displaying the tetrad effect intensive post magmatic alteration of the granite occurred along brittle structures at least two main stages of post magmatic hydrothermal alteration are involved the first high temperature stage which is characterized by albitization and or quartz leaching episyenitization resulted from fluid rock interaction with late magmatic fluids that very probably mixed with external low salinity fluids quartz dissolution was triggered by vapour condensation and or the cooling of these fluids below 450 c along brittle structures the high porosity resulting from quartz leaching during stage 1 assisted subsequent circulation of low temperature fluids at stage 2 the latter is characterized by the chloritization and illitization of episyenites almost all major and trace elements were enriched or depleted during one of the main alteration stages however zr hf th and ti were immobile during post magmatic alteration the significant depletion of lree and the enrichment of hree in albitized samples is controlled by the dissolution of monazite and the new formation of hree rich polycrase y or aeschynite y during post magmatic stage 1 negative ce anomalies of episyenites are associated with illitization and suggest oxidizing conditions during stage 2

outstanding issues in excavation of deep and long rock tunnels a case study excavation of deep and long tunnels faces several distinctive challenges such as unknown geological structures high groundwater pressure and high in situ stress as compared with conventional tunnels the deep and long taining tunnel in fujian province south china was excavated in complex geological settings this tunnel had to pass through various squeezing fault zones and intensely jointed zones large deformations and high pressure groundwater were frequently encountered during excavation to predict the potential adverse geological structures a comprehensive method which included tunnel seismic prediction and ground penetration radar detection as well as horizontal drilling was developed energy release and pressure reduction as well as timely sealing pre excavation curtain grouting and radial grouting were adopted to control the high pressure groundwater countermeasures including improvement of support stiffness double layered primary support and pre support increase of preset deformati

grouting for water and mud inrush control in weathered granite tunnel a case study abstract this paper presents a case study of curtain grouting to prevent water and mud inrush disasters for a weathered granite tunnel in guangxi china first the basic information of the junchang tunnel is given including ground conditions water and mud inrush disasters and the subsequent prevention countermeasures then we present the original grouting design and procedure and the field operation of 25 grouting cycles and excavations for the evaluation of the grouting effect and suggestion for future grouting work based on the field investigation the values of the major grouting parameters are suggested including grouting thickness of 5 8 m grouting length of 15 18 m 3 3 6 times of thickness and per meter grouting volume of 34 2 m3 furthermore the guidelines for composite materials selection are proposed for the various flowing water environments moreover the space positions and water quality of the inspection boreholes and the original water richness of the ground should be taken into consideration in the grouting evaluation criteria the optimized grouting parameters materials selection and evaluation criteria provide important references for disasters prevention in similar projects

deformation failure and permeability of coal bearing strata during longwall mining abstract to mitigate water shortage a few groundwater reservoirs are being built at the daliuta coal mine shaanxi province china it is essential to investigate the deformation failure and permeability of coal bearing strata during longwall mining and their influences on the construction of groundwater reservoirs in this paper the local geology was introduced briefly and the complete stress strain and permeability for different rock samples were investigated using laboratory experiments and then a three dimensional coupling model between stress and permeability was proposed after that a series of numerical simulation was performed to investigate the dynamics of stress permeability coefficient using flac3d it turns out that due to the relatively low mechanical strength of the coal bearing strata at the daliuta coal mine there are only two zones above the goaf that is caving zone and fracture zone and the fracture zone extends directly to the surface the rock mass permeability is closely related to the stress strain and the permeability decreases with the rise of stress in the stage of elastic deformation while it increases significantly in the stages of plastic deformation and failure the maximum value of permeability coefficient appears in the stage of strain softening and the value varies greatly with the rock lithology during the advancement of longwall face the redistribution range is much wider for permeability than for rock failure and the permeability is the largest on the periphery of goaf rock mass with increased permeability is horizontally oval shaped and vertically saddle shaped the permeability of coal seam roof and floor experiences three stages decrease increase and gradual recovery during coal mining the results are in good agreement with those of physical modeling and field observation the outcomes may contribute to the site selection and construction of the groundwater reservoir at the daliuta coal mine

impact of karst water on coal mining in north china coalfields in north china encompass more than ten provinces they contain six to seven coal seams in the permo carboniferous strata the lower three seams account for 37 of the total reserves and are threatened with intrusion of karst water from the underlying ordovician limestone hundreds of water inrush incidences have occurred in which a large amount of water suddenly flows into tunnels or working faces under high potentiometric pressure over 50 mines have been flooded over the last 30 years large scale dewatering or depressurizing of the karst aquifer was considered essential to avoid water inrushes and keep the mines safely operational this practice however has caused sinkholes dry springs water supply shortage and groundwater contamination in the surrounding areas one alternative water control measure is to make full use of the rock layer between the coal seam and the karst aquifer as a protective barrier to prevent or constrain water flow from the underlying aquifer into the mines grouting is effective when the hydrogeological conditions are favorable to this technique proper design of the grouting program and experience of the contractor are also important for a successful application

constraining the enceladus plume using numerical simulation and cassini data abstract since its discovery the enceladus plume has been subjected to intense study due to the major effects that it has on the saturnian system and the window that it provides into the interior of enceladus however several questions remain and we attempt to answer some of them in this work in particular we aim to constrain the h2o production rate from the plume evaluate the relative importance of the jets and the distributed sources along the tiger stripes and make inferences about the source of the plume by accurately modeling the plume and constraining the model using the cassini inms and uvis data this is an extension of a previous work yeoh s k et al 2015 icarus 253 205 222 in which we only modeled the collisional part of the enceladus plume and studied its important physical processes in this work we propagate the plume farther into space where the flow has become free molecular and the cassini inms and uvis data were sampled then we fit this part of the plume to the inms h2o density distributions sampled along the e3 e5 and e7 trajectories and also compare some of the fit results with the uvis measurements of the plume optical depth collected during the solar occultation observation on 18 may 2010 we consider several vent conditions and source configurations for the plume by constraining our model using the inms and uvis data we estimate h2o production rates of several hundred kgs 1 400 500 kg s during the e3 and e7 flybys and 900 kg s during the e5 flyby these values agree with other estimates and are consistent with the observed temporal variability of the plume over the orbital period of enceladus hedman m m et al 2013 nature 500 182 184 in addition we determine that one of the tiger stripes cairo exhibits a local temporal variability consistent with the observed overall temporal variability of the plume we also find that the distributed sources along the tiger stripes are likely dominant while the jets provide a lesser contribution moreover our best fit solutions for the plume are sensitive to the vent conditions chosen the spreading angle of the jet produced is the main difference among the vent conditions and thus it appears to be an important parameter in fitting to these inms data sets in general we find that narrow jets produce better fits suggesting high mach numbers 5 at the vents this is supported by certain narrow features believed to be jets in both the inms and uvis data sets this tends to rule out sublimation from the surface but points to a deep underground source for the plume however the underground source can be either sublimation from an icy reservoir or evaporation from a liquid reservoir a high mach number at the vent also suggests subsurface channels with large variations in width and not fairly straight channels so that the gas can undergo sufficient expansion additionally the broad spreading angles inferred for the m sized grains ingersoll a p and ewald s p 2011 icarus 216 492 506 postberg f et al 2011 nature 474 620 622 cannot be due to spreading by the gas above the surface alone some other mechanism s must also be responsible perhaps occurring below the surface which further points to an underground source for the plume

characteristics of dewatering induced drawdown curve under blocking effect of retaining wall in aquifer summary for deep excavation pits that require the pumping of confined groundwater a combination of a retaining wall and dewatering with large diameter wells is usually adopted during excavation to improve safety since a retaining wall has a much lower hydraulic conductivity than the surrounding material in the aquifer blocking of seepage to prolong the seepage path of the groundwater outside of the pit is effective the retaining walls used during excavation dewatering cause hydraulic head drawdown inside the pit much faster than outside the pit thus difference in hydraulic head between inside and outside of the pit increases to investigate the mechanism of the blocking effect numerical simulation using the finite difference method fdm was conducted to analyze the effects of pumping in the pit the fdm results show that drawdown varies along the depth of the confined aquifer the influence factors of drawdown inside and outside the pit include insertion depth of retaining walls anisotropy of a confined aquifer and screen length of pumping wells in addition fdm results also show that the drawdown time curve can be divided into four stages in stage i drawdown inside the pit is very small and outside the pit it is almost zero in stage ii drawdown increases quickly with time in stage iii the drawdown curve is parallel to the cooper jacob curve on semi log axes and in stage iv the drawdown becomes constant these characteristics of the drawdown curve under the blocking effect of a retaining wall in an aquifer provide a way of estimating hydrogeological parameters according to pumping test results

semi analytical solution to pumping test data with barrier wellbore storage and partial penetration effects abstract there exist some difficulties in determining aquifer parameters based on pumping test data within a partially penetrated retaining walls using traditional cooper jacob method many other site specific factors such as the effect of partially penetrating well and the large diameter of the wells cannot easily be accommodated in theoretical well formulae the semi log drawdown time curves affected by the effects of barrier wellbore storage and partial penetration well can be characterised by four distinct stages of drawdown i stage i drawdown is unaffected by the barrier ii stage ii drawdown is significantly influenced by the barrier iii stage iii the drawdown time curve runs parallel to that deduced from greenfield conditions and iv stage iv the drawdown becomes a constant value to handle the four distinct stages of drawdown a semi analytical method using the slope of the late time drawdown asymptote of stage iii for determining the transmissivity is proposed the horizontal intercept resulting from an extension of the late time drawdown asymptote from stage ii is used for determining the storage coefficient pumping test data from a case history are analysed using the proposed semi analytical method and the results obtained are compared with those deduced from the numerical simulation the comparison between the analytical results and those obtained from the numerical simulation appeared satisfactory

investigation of field installation effects of horizontal twin jet grouting in shanghai soft soil deposits this paper presents a case study of an investigation into the responses of the surrounding ground to the horizontal twin jet grouting method htjgm in soft soil deposits of shanghai during the fi

groundwater control around a large basement melbourne s crown casino was constructed on a site bordering the yarra river and underlain by problem soils of the coode island silt formation the development needed to provide two levels of basement car park over the entire site an innovative approach to groundwater control around the excavation was required to avoid depressurisation of adjoining soils leading to settlements analysis showed a conventional bentonite cut off wall would still allow depressurisation by lateral flow through the coode island silt during the construction period the high cost and construction difficulty of a very low permeability wall mitigated against it an hydraulic wall was proposed in conjunction with a conventional cut off wall this comprised a curtain of wick drains surrounding the cut off wall and charged with water control of seepage through an underlying aquifer by a cut off wall was considered but a more cost effective method using recharge by wells was adopted when shown necessary monitoring of groundwater p

spatial variations in the dust to gas ratio of enceladus plume abstract on day 138 of 2010 the plume of dust and gas emerging from enceladus south polar terrain passed between the sun and the cassini spacecraft this solar occultation enabled cassini s ultraviolet imaging spectrograph uvis and the visual and infrared mapping spectrometer vims to obtain simultaneous measurements of the plume s gas and dust components along the same lines of sight the uvis measurements of the plume s gas content are described in hansen et al 2011 grl 38 11202 while this paper describes the vims data and the information they provide about the plume s particle content together the vims and uvis measurements reveal that the plume material above baghdad and damascus sulci has a dust to gas mass ratio that is roughly an order of magnitude higher than the material above alexandria and cairo sulci similar trends in the plume s dust to gas ratio are also found in data obtained when cassini flew through the plume in 2009 during which time the ion and neutral mass spectrometer inms radio and plasma wave science instrument rpws and cosmic dust analyzer cda instruments made in situ measurements of the plume s gas and dust densities dong et al 2015 jgr 120 915 937 these and other previously published systematic differences in the material erupting from different fissures likely reflect variations in subsurface conditions across encealdus south polar terrain

identification remediation and analysis of karst sinkholes in the longest railroad tunnel in south korea abstract tunneling in karst terrains presents numerous challenges to the engineer including the unpredictable occurrence of cavities and well developed hydraulic conduits that could lead to sinkhole development during construction of the longest railroad tunnel in south korea excessive water inrushes and support collapses accompanying the formation of a couple of sinkholes and subsidence on the ground surface such cases of sinkhole formation during tunneling in south korea have been rarely reported various characterization methods were used at the tunneling site to identify the causes of the sinkholes and the subsidence on the ground surface especially noteworthy in this regard is that the massive limestone in this area contains a high degree of lime purity as high concentrations of lime are very corrosive a limestone micro scale cavity readily developed along the fault planes and joints due to weathering and chemical corrosion the data obtained from various types of geological and geophysical exploration methods identified the formation of micro scale cavity networks that served as conduits carrying reservoir water from the surface to the underground tunnel additional micro scale vertical cavity networks were detected for the unexcavated tunnel route through geophysical and horizontal probe core drilling methods ground reinforcement was applied to sinkhole and subsidence at the ground surface and the cavity inside the tunnel for remediation after the installation of underground waterproof grouting around the tunnel and of grouting walls around the sinkholes the groundwater level recovered and the ground surface settlement ceased seepage analyses were performed to provide an optimal drainage design for long term stability based on this case study and the lessons learned we suggest a risk reduction system for safe tunneling in karst terrains

workability compressibility and hydraulic conductivity of zeolite amended clayey soil calcium bentonite backfills for slurry trench cutoff walls soil bentonite slurry trench cutoff walls using backfill consisting of on site sandy soil and na bentonite are extensively used as engineering barriers for the purpose of achieving relatively low hydraulic conductivity the amendments such as zeolite to backfill are considered to improve the contaminant sorptive capacity at some sites local clayey soil ca bentonite and natural zeolite may be available for an alternate backfill however studies on the workability in terms of slump compressibility and hydraulic conductivity of such zeolite amended clayey soil ca bentonite backfills for the cutoff walls are very limited this paper presents a comprehensive laboratory investigation on the workability compressibility and hydraulic conductivity of fine grained zeolite amended clayey soil ca bentonite backfills using several series of slump and oedometer tests kaolin is used as the model clayey soil and it is amended with various amounts of ca bentonite 7 8 8 4 and zeolite 10 40 to prepare zeolite amended kaolin bentonite backfills the test results are compared with previous studies on zeolite amended sandy soil na bentonite backfills as well as compacted zeolite bentonite liners to assess the effects of zeolite content and zeolite grain size on the compressibility and hydraulic conductivity the results indicate that the water content required to achieve a target slump 100 150 mm for the backfills increases with increasing zeolite content liquid limit can be a useful index for a preliminary estimation of the water content required to achieve the target slump for the backfills presented in this study and zeolite amended sandy soil na bentonite backfills reported in previous studies the results reveal that the hydraulic conductivity of the zeolite amended clayey soil ca bentonite backfills with void ratio ranging from 0 54 to 1 45 is generally lower than the typical regulatory limit 10 9 m s the addition of fine grained zeolite has insignificant influence on the compressibility and hydraulic conductivity of both clayey soil ca bentonite and sandy soil na bentonite backfills a proposed empirical method based on the framework of kozeny carman equation can predict the hydraulic conductivity of zeolite amended clayey soil ca bentonite backfills values within the range of 1 3 to 3 times those calculated from the oedometer tests the proposed method is also shown to estimate the hydraulic conductivity of the compacted zeolite bentonite liners from previous studies with reasonable accuracy additional research is recommended to evaluate the proposed zeolite amended backfill using tap water and also by direct measurement of hydraulic conductivity using falling head or constant head testing method

assessment of the engineering behavior of ultramafic and mafic rocks using chemical indices geochemistry is of great importance for the interpretation of the geomechanical quality of rock materials used in various construction applications this paper investigates the interrelationships between selected chemical indices and various engineering parameters of ultramafic and mafic rocks from the vourinos pindos koziakas and othrys ophiolite complexes northern and central greece the significance of these indices for the engineering assessment of ophiolitic aggregates is strongly demonstrated based on statistical analysis of the experimental results the studied lithologies include dunites olivine rich harzburgites typical harzburgites plagioclase bearing lherzolites troctolites diorites and dolerites which show various degrees of alteration and tectonic deformation the effect of alteration on rock strength and particularly the relationships between specific chemical indices and the engineering parameters are determined using simple regression analysis the results designate that the wpi index is the most appropriate for the assessment of the engineering behavior of ultramafic lithologies while the loi index seems to provide a general estimation of the strength properties of mafic rocks

aquifer recharge using a partially penetrating well with clogging induced permeability reduction abstract well and aquifer clogging is one of the most serious problems restricting the application of managed aquifer recharge mar to address the clogging issue this study proposes an innovative model using partially penetrating wells ppw in confined aquifers while considering the clogging related permeability as an exponentially decayed function of time based on analysis of in situ observation data a combination of hankel transform and finite fourier cosine transform is adopted to solve the model the quasi solutions at early and late times and steady state are also derived using the developed analytical solution the developed solutions can be used to investigate the independent or combined effect of clogging induced permeability reduction well configuration and aquifer anisotropy on groundwater flow dynamics in confined aquifers or inversely used for estimating parameters associated with the clogging effect and aquifer property based on a semi log graphic approach the findings of this study can help for better understanding of the flow behaviors in the confined aquifers suffering clogging and find application in the estimation and prediction of well and aquifer clogging in mar using aquifer injection wells