uncertainty analysis of tunnel squeezing for two tunnel cases from nepal himalaya abstract weak rocks such as shale slate phyllite and schist and the rock mass of weakness fault zones are incapable of sustaining high tangential stress severe tunnel squeezing is therefore common in the tectonically active himalayan rock mass and is one of the major areas of concern regarding stability a reliable prediction of the extent of squeezing is essential so that a strategy can be established regarding stabilizing measures and for optimizing the support well in advance during planning and design in this paper a probabilistic approach to uncertainty analysis that focuses on the effect of the variations in each input parameter of squeezing is used for analyzing and predicting the extent of tunnel squeezing for two tunnel cases in nepal kaligandaki a completed and middle marsyangdi under construction a semi analytical method suggested by hoek and marinos predicting tunnel squeezing problems in weak heterogeneous rock masses tunnels tunnell int 2000 32 11 and 12 45 51 and 34 36 for predicting squeezing an empirical formula proposed by panthi analysis of engineering geological uncertainties related to tunnelling in himalayan rock mass conditions phd thesis department of geology and mineral resources engineering norwegian university of science and technology ntnu norway 2006 and the palisade s 2002 version of risk statistical software program have been used for the uncertainty analysis the analysis results for kaligandaki indicate fairly good correlation between predicted and actually measured squeezing the same approach has been used for predicting the degree of tunnel squeezing at middle marsyangdi tunnel it is concluded that the methodology proposed in this paper has potential for predicting the squeezing of future tunnel projects in weak rock mass conditions

the bering slope current system revisited mean circulation and water properties within the aleutian basin of the bering sea are investigated using hydrographic and subsurface park pressure displacement data from a regional array of 14 profiling ctd floats after 10 days drifting at 1000 dbar each float measures temperature and salinity profiles as it rises to the surface and then transmits these data via satellites which also make several fixes of the float surface positions before it sinks again every fourth cycle the floats sink from 1000 dbar to a 2000 dbar target just prior to ascent to measure deeper profiles the 1000 dbar displacements estimated from the float surface position fixes reveal a coherent few centimeters per second northwestward flow along the northeastern boundary the deep signature of the bering slope current middepth water property distributions are consistent with cyclonic advection of warm water from the south around the basin eastward in the aleutian north slope current and then northwestward in the bering slope current geostrophic transport estimates relative to 1000 dbar also show cyclonic motion although with significant noise likely owing to the influence of mesoscale eddies the mean alongslope geostrophic transport of the bering slope current is determined between 0 and 1900 dbar relative to 1000 dbar and then combined with mean along slope velocities at 1000 dbar the result is an absolute geostrophic transport estimate with 95 confidence intervals for the along slope current offshore of the 1000 m isobath and between 0 and 1900 dbar of 5 8 61 7 3 106 m3 s 21

effects of mesoscale eddies on the flow of the alaskan stream 1 using a high resolution pan arctic ice ocean model forced with realistic atmospheric data we examine the mean transport and temporal and spatial variability within the alaskan stream model results are analyzed and compared with observations including satellite altimetry and ctd measurements the mean net transport of the alaskan stream is found to be between 34 and 44 sv intensifying downstream mesoscale eddies are found to periodically move along the path of the alaskan stream and alter the mean position of the typically westward flowing current however the strength of the current is not reduced as an anticyclonic eddy passes a point along the path instead there appears to be an offshore or southward shift in the current velocity core stationary measurement instruments may not be able to detect this shift in position over the slope if their southernmost location does not coincide with the current shift due to an eddy this may result in recording of a weakened or sometimes reversed flow finally we examine and demonstrate that modeled eddies within the alaskan stream have dominant effect on northward transport and variability through the eastern and central aleutian island passes

zooplankton community composition along the inner portion of line p during the 1997 1998 el nino event the 1996 1999 zooplankton samples from oceanic waters off southern british columbia provide time series descrip tions of biomass and community composition before during and immediately after the 1997 1998 el nino event our most frequent sampling every month in 1998 and three to four times per year in other years was off southern van couver island and extended seaward from the shelf break to approximately 200 km offshore along and adjacent to the inner third of the long term line p station p section 48 30 49 n 126 130 40w el nino associated changes in the zooplankton community were most apparent over the shelf break and slope and weaker further offshore at the nearshore portion of this line p03 p06 the 1997 1998 differences from long term seasonal averages included both lower total biomass and shifts in community composition reduced abundance of endemic boreal temperate species increased abundance of mid california neritic and oceanic species toward the seaward end of the section p08 p12 changes of zooplankton species composition were much less apparent and the main signal associated with the 1997 1998 event was an early and narrow spring peak of neocalanus spp although most extreme in 1998 both the nearshore and offshore sets of anomalies were continuations of trends that had developed progressively off british columbia through the 1990s a few taxa normally endemic to southern parts of california current and previously absent or very rare off british columbia appeared in our samples in 1997 1998 and persisted through summer of 1998 and at some locations into 1999 the changes observed over the continental slope of vancouver island were very similar to the observations of 1970s versus late 1990s differences in the zooplankton of the central oregon coast continental shelf pices sci rep 10 1999 45 prog oceangr 2002 suggesting that there was alongshore continuity of both oceanic forcing and zooplankton response crown copyright 2002 published by elsevier science ltd all rights reserved

geographical variability of the first baroclinic rossby radius of deformation global 1 83 18 climatologies of the first baroclinic gravity wave phase speed c1 and the rossby radius of deformation l1 are computed from climatological average temperature and salinity profiles these new atlases are compared with previously published 5 83 58 coarse resolution maps of l1 for the northern hemisphere and the south atlantic and with a 1 83 18 fine resolution map of c1 for the tropical pacific it is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5 15 owing to seemingly minor computational errors geographical variations in the new high resolution maps of c1 and l1 are discussed in terms of a wkb approximation that elucidates the effects of earth rotation stratification and water depth on these quantities it is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c1 and l1 at any particular location in the world ocean this is rationalized from consideration of the wkb approximation

circulation in shelikof strait alaska abstract extensive hydrographic surveys were conducted in shelikof strait in march and october 1985 the data are used to describe circulation and property distributions and the changes that occurred the upper layer flows to the southwest throughout the year but greatest speeds occur in the fall when surface waters are least saline because of a maximum in freshwater discharge the deep water has its source to the south and the properties seem to result from vertical mixing of this southern water thus shelikof strait has an estuarine like circulation with a northward deep inflow property distribution showed that isolines were usually deepest on the right side of the channel looking to the southwest greatest baroclinic speeds were often there also differential ekman pumping may contribute to the development of this structure and its changes volume transport estimates varied considerably in october the southwest flow bifurcated with part continuing along the alaska peninsula and the rest exiting t

downslope volume enlargement of a debris slide debris flow in the 1999 hiroshima japan rainstorm abstract following a heavy rainstorm on 29 june 1999 hundreds of slope failures occurred in granitic mountains in hiroshima prefecture japan among these events a highly mobile landslide termed the kameyama landslide in this paper which occurred in kameyama area of hiroshima city was the most catastrophic and was investigated in detail the displaced soil mass from the source area of this landslide traveled about 300 m and deposited a volume more than 10 times as great as that in the source area the landslide originated in and traversed a valley shaped concave slope covered by pre existing colluvial debris deposits in addition a spring was visible in the source area and very shallow ground water was observed in an observation pit dug in the source area thus it is inferred that the ground water table rose quickly during the rainfall and that this rise triggered the slope failure in the source area based on a field survey along the landslide cross section a possible explanation for the mechanism of the landslide was obtained the displaced soil mass from the source area impacted the debris deposit in the path of the landslide thus triggering liquefaction failure of the saturated part of debris the original landslide and the liquefied debris then moved downslope as a single mass to examine this assumption ring shear tests were performed on samples taken from the source area undrained ring shear tests on the saturated samples showed that the sample is highly liquefiable and liquefaction failure could have been triggered in the debris deposits by a very small impact from the displaced soil mass of the initial failure in addition laboratory tests simulating the impacts on the debris deposits at natural water content i e unsaturated at the survey time 2 days after the failure showed that although shear failure could be caused by the assumed impact force the displaced soils stopped after a few centimeters displacement indicating that existence of a saturated zone in debris deposits is prerequisite for this kind of failure

observations of topographic planetary waves in the bering slope current using the geosat altimeter topographic planetary waves associated with the downstream leg of the bering slope current are observed in measurements of sea surface height anomalies acquired by the geosat altimeter during 1987 and 1988 the waves are most prominent from may to august 1987 during which time the estimated wave period and wavelength are about 72 days and 103 km respectively the direction of propagation is roughly north northeast

countermeasures to treat collapse during the construction of road tunnel in fault zone a case study from the yezhuping tunnel in south qinling china to ensure the safety of the tunnel construction it is very important to take the appropriate treatment measures after the collapse happened especially the tunnel goes through the fault fracture zone this paper sets forth the process of the collapse that occurred in the yezhuping tunnel affected by the fault fracture zone and introduces the treatment for the collapse the deformation characteristics of the surrounding rock are analyzed according to the monitoring results based on the research regarding the effect of the fault on the tunnel by using the general hoek brown failure criterion and the field monitoring results it is shown that the fault is the main reason for the collapse it induces the attenuation of the young modulus and the compressive strength and the enlargement of the plastic zone the research results have some reference significance for similar projects

cold core anticyclonic eddies south of the bussol strait in the northwestern subarctic pacific abstract summer hydrographic surveys from 1993 to 1997 in the area south of the kuril islands in the northwestern subarctic pacific showed the existence of anticyclonic eddies south of the bussol strait at almost the same location but with variable sizes and intensities depending on the year every eddy had a cold low salinity and low potential vorticity core suggesting a strong influence from the okhotsk sea water two formation processes and annual variations were found with satellite data analyses one is the case where eddies are locally formed south of the bussol strait and intensified from summer to fall with the supply of okhotsk sea water as observed in 1993 in the other case kuroshio warm core rings that had translated northeastward are arrested near the bussol strait and amplified with the supply of okhotsk sea water as seen from summer to autumn in 1995 in winter eddies tend to move northeastward with decay the 1992 eddy moved northeastward then northward in winter and was eventually

critical density of sand although hardly used in theoretical soil mechanics nowadays critical density still is an important parameter in cases where the flow slide susceptibility of sand deposits has to be investigated in this paper two types of triaxial tests in which the critical porosity of sand is measured are described during the first type of test on dry sand the volume change is measured in the second type of test undrained and stress controlled on saturated sand the sudden collapse and liquefaction of the loose samples is observed the results of the two tests are related to each other by means of calculations and a more safe criterion is derived in the wet critical porosity the unsafe influences of membrane penetration and of insufficient saturation are removed with this method the sudden failure and liquefaction of saturated samples under stress controlled but completely drained conditions could be explained quoique rarement utilisee a l heure actuelle dans les travaux theoriques relatifs a la mecanique du

mesoscale eddies dominate surface phytoplankton in northern gulf of alaska abstract the hnlc waters of the gulf of alaska normally receive too little iron for primary productivity to draw down silicate and nitrate in surface waters even in spring and summer our observations of chlorophyll sensed by seawifs north of 54 n in pelagic waters 500 m depth of the gulf found that on average more than half of all surface chlorophyll was inside the 4 cm contours of anticyclonic mesoscale eddies the ratio approaches 80 in spring months yet these contours enclosed only 10 of the total surface area of pelagic waters in the gulf therefore eddies dominate the chlorophyll and phytoplankton distribution in surface pelagic waters we outline several eddy processes that enhance primary productivity eddies near the continental margin entrain nutrient and fe rich and chlorophyll rich coastal waters into their outer rings advecting these waters into the basin interior to directly increase phytoplankton populations there in addition eddies carry excess nutrients and iron in their core waters into pelagic regions as they propagate away from the continental margin as these anticyclonic eddies decay their depressed isopycnals relax upward injecting nutrients up toward the surface layer we propose that this transport brings iron and macro nutrients toward the surface mixed layer where they are available for wind forced mixing to bring them to surface these mesoscale eddies decay slowly but steadily perhaps providing a relatively regular upward supply of macro nutrients and iron toward euphotic layers they might behave as isolated oases of enhanced marine productivity in an otherwise iron poor basin we note that much of this productivity might be near or just below the base of the surface mixed layer and therefore poorly sampled by colour sensing satellites it is possible then that eddies enrich phytoplankton populations to a greater extent than noted from satellite surface observations only

evolution and modulation of a poleward propagating anticyclonic eddy along the japan and kuril kamchatka trenches to investigate the relationships between the movement of an eddy and its interior structure and water properties four profiling floats were deployed in an anticyclonic eddy in the western north pacific in 2013 april october daily float profiles showed rapid changes in temperature and salinity corresponding to strong interactions between eddies north of the subtropical kuroshio extension after the first interaction with a warm core eddy in april the isolation of the winter mixed layer from the surface was observed forming a subsurface remnant layer another interaction with a cold fresh eddy at middepths in may resulted in the formation of a multilayer structure the eddy then moved poleward along the japan and kuril kamchatka trenches indicating changes in its propagation pattern coupled to its interior structure the eddy then moved northward june july stalled july august and moved eastward august october in addition to a general declining trend the properties of the warm saline core changed over a short time period coinciding with changes in propagation a density anomaly at middepths of the eddy changed location during the stalled period however denser waters were continuously observed in the southeast part of the eddy during its northward and eastward movement this unidirectional density anomaly pattern was consistent with the structure of the poleward propagating eddy which interacted with the western topographic boundary meridional exchanges of heat and material were potentially elevated by the eddy s advection and movement as well as by water modifications in the eddy associated with exchanges along its perimeter

anticyclonic eddies in the alaskan stream abstract anticyclonic eddies propagating southwestward in the alaskan stream as were investigated through analysis of altimetry data from satellite observations during 1992 2006 and hydrographic data from profiling float observations during 2001 06 fifteen long lived eddies were identified and categorized based on their area of first appearance three eddies were present at the beginning of the satellite observations another three formed in the eastern gulf of alaska off sitka alaska and four were first detected at the head of the gulf of alaska near yakutat alaska the other five eddies formed along the as between 157 and 169 w and were named as eddies while the eddies that formed in the gulf of alaska mainly decayed before exiting the gulf of alaska the as eddies mostly crossed the 180 meridian and reached the western subarctic gyre four of five as eddies formed under negative or weakly positive wind stress curls which possibly caused as separation from the coast comparison of eddy propag

a sliding consolidation model for flow slides a model is proposed for the behaviour of flow slides in loose cohesionless materials in which the debris spreads out as a uniform sheet excess pore fluid pressures are assumed to be generated for example by undrained loading arising from the collapse of metastable structure in the source area of the flow slide under the influence of these the leading element of the debris moves downslope by basal sliding consolidating as it does so by single upward drainage as a result the pore pressure at the base of the element eventually decays to a value that brings the element to rest hence defining the run out of the flow slide the model is applicable in principle to subaqueous and subaerial flow slides and to pore fluids consisting of water gas or both of these the predictions of the model are tested against the observed behaviour and measured properties of the 1966 flow slide at aberfan south wales the results show that a sliding consolidation model provides a possible mechanism for that event

an eddy resolving model of circulation on the western gulf of alaska shelf 2 comparison of results to oceanographic observations currents generated by an eddy resolving semispectral primitive equation model are compared with those measured by moored current meters 1989 and 1991 and satellite tracked drifting buoys 1987 from shelikof strait alaska the model reproduced many of the dominant circulation features including the cross sectional spatial structure of the alaskan coastal current the estuarine inflow at the bottom of the sea valley and the mean transport the first mode empirical orthogonal functions of the model and of the observed data represent similar spatial structures and were significantly correlated in time while the model produced eddies 20 km diameter at a similar rate as observed the timing did not generally match the observations as a result correlations between the measured currents and model generated currents usually were not significant correlations between modeled and measured transport through the sea valley however were significant for both years

a note on cross shelf exchange in the northern gulf of alaska the continental shelf of the gulf of alaska goa is a complex system characterized by large freshwater runoff and strong winds the goa supports one of the world s richest ecosystems including numerous species of fishes marine mammals and sea birds the mechanisms that provide nutrients to support this ecosystem are not well understood the rivers and streams that provide freshwater to the shelf are low in nitrate and the regional winds favor downwelling high concentrations of nitrate are available in the deep basin of the goa but these must be introduced to the shelf in order to support the high productivity we present evidence for cross shelf exchange due to three different mechanisms episodes of downwelling relaxation result in a flux of saline nutrient rich water onto the shelf at depth eddies formed in the northeastern goa propagate along the shelf break influencing cross shelf exchange by carrying shelf origin water from the formation region into the basin and by interacting with the shelf break circulation bathymetric steering in the many canyons that incise the goa shelf results in flow into the canyons where strong tidal mixing results in cross isobath movement of water properties

geographic and seasonal distributions of brunt vaisala frequency and rossby radii in the north pacific and north atlantic abstract long term mean temperature and salinity profiles computed from an edited set of historical hydrographic data have been used to calculate mean profiles of density and brunt vaisala seasonal variations in internal rossby radii are everywhere surprisingly small

a major circulation anomaly in the western bering sea the alaskan stream ceased to flow northward into the western bering sea starting in summer 1990 this unexpected lack of inflow caused by a southward shift in the path of the alaskan stream persisted through at least fall 1991 if the anomalous flow continues substantial changes in the physical environment will occur possibly leading to impacts on the rich fisheries stocks in the region

heat and fresh water transport by eddies into the gulf of alaska abstract anticyclonic mesoscale eddies form in winter along the continental margin of canada and southeast alaska between the latitudes of 51n and 60n and drift westward into the gulf of alaska carrying warmer fresher water away from the continental margin detailed measurements of temperature and salinity between 1995 and 2001 were examined to determine the amount of heat and fresh water transported seaward by several eddies that formed west of the queen charlotte islands eddies formed in a typical winter carry about 30 10 18 j of heat into the gulf which is about 35 to 60 of the heat transported northward each winter along the continental margin toward this region the observed range of eddy heat transport is 10 19 to 10 20 j largest observed eddy heat transport coincided with increased northward heat flow along the continental margin during the el nino winter of 1997 1998 fresh water volume was determined by evaluating the amount of fresh water required to reduce the salinity from a reference level to that observed in eddies this volume varied from 0 to 70 km 3 and was largest during the 1997 1998 el nino winter eddies formed in a typical winter transport 50 km 3 of fresh water seaward which is about 15 of the estimated fresh water input to the continental margin in winter between the columbia river and 54n attributed to local runoff plus direct rainfall and flow in major rivers

anomalous eddy heat and freshwater transport in the gulf of alaska characteristics of eddies in the gulf of alaska are assessed from january 2003 through april 2012 ensemble statistics for eddy subsurface water properties on isopycnals are computed using temperature and salinity profiles from argo profiling floats located within eddies which are identified in sea surface height using objective techniques ninety cyclonic and 154 anticyclonic eddies are identified during this period the anticyclonic eddies are strongly nonlinear and exhibit significant warm subsurface temperature anomalies and associated salty anomalies on isopycnals while no clear distinguishing subsurface anomalies on isopycnals are detected in association with the cyclonic eddies heat and freshwater fluxes for the eddies are estimated from integrations in depth coordinates the anticyclonic eddies transport heat both westward off the continental shelf into the subarctic gyre and westward within the alaskan stream however they transport salt into the subarctic gyre and freshwater within the alaskan stream in both pathways eddy heat and freshwater transport show possible year to year fluctuations varying from 0 to 50 4 1018 j a 1 and 16 8 to 7 4 km3 a 1 respectively the anticyclonic eddies are capped by relatively fresh water year round

numerical investigation of the hydromechanical response of a natural fracture during fluid injection using an efficient sequential coupling model hydraulic fracturing is a complicated hydromechanical coupled process especially in shale gas and deep geothermal reservoirs in which natural fractures exist due to the geological complexity caused by invisibility and the challenge and high cost in field investigations numerical modeling becomes an alternative in this paper an integrated numerical model is developed to investigate the hydromechanical behavior of a natural fracture during the fluid injection in the developed model the mechanical behavior of the fracture including fracture opening closure shear dilation and shear failure is described by proposed constitutive equations meanwhile the hydraulic process is simplified as the fluid flows through two parallel planes the coupled mechanical and hydraulic equations are sequentially formulated in an implicit schema by combining the finite different method and the finite volume method the advantage of this numerical schema is that the two coupled processes are solved separately and only one sub iteration is needed thus the solution is efficient and stable than that formulated in a monolithic coupling besides the implicit formulation of the flow equation makes it possible to set a relative large time step the developed model is verified through three numerical examples then it is used to investigate the hydromechanical behavior of a natural fracture during the fluid injection with a fictive reservoir sensitivity studies with variations in the stress state the fluid injection rate the fluid viscosity and the injection form are conducted the simulation results show that the mechanism in the far field is mainly dominated by shear dilation in contact condition whereas the mechanism near the injection could be mixed shear tension in either the contact or the separation conditions with the increase in the shear stress and the injection length decrease in the injection rate and the fluid viscosity the fracture state near the injection will change from separation to contact the injection pressure will decline below the primary normal stress and the dominated mechanism is shear dilation the findings in this study give a better understanding of the mechanical mechanism and the pressure response of a natural fracture during the fluid injection

altimeter derived surface circulation in the large scale ne pacific gyres part 1 seasonal variability abstract the seasonal variability of sea surface height ssh and currents are defined by analysis of altimeter data in the ne pacific ocean over the region from central america to the alaska gyre the results help to clarify questions about the timing of seasonal maxima in the boundary currents as explained below the long term temporal mean of the ssh values must be removed at each spatial point to remove the temporally invariant and large signal caused by the marine geoid we refer to the resulting ssh values which contain all of the temporal variations as the residual ssh our main findings are 1 the maximum surface velocities around the boundaries of the cyclonic alaska gyre the alaska current and the alaska stream occur in winter at the same time that the equatorward california current is weakest or reversed forming the poleward davidson current the maximum surface velocities in the california current occur in summer these seasonal maxima are coincident with the large scale atmospheric wind forcing over each region 2 most of the seasonal variability occurs as strong residuals in alongshore surface currents around the boundaries of the ne pacific basin directly connecting the boundaries of the subpolar gyre the subtropical gyre and the equatorial current system 3 seasonal variability in the surface velocities of the eastward north pacific current west wind drift is weak in comparison to seasonal changes in the surface currents along the boundaries 4 there is an initial appearance next to the coast and offshore migration of seasonal highs and lows in ssh alongshore velocity and eddy kinetic energy eke in the alaska gyre similar to the previously described seasonal offshore migration in the california current 5 the seasonal development of high ssh and poleward current residuals next to the coast appear first off central america and mainland mexico in may june prior to their appearance in the southern part of the california current in july august and their eventual spread around the entire basin in november december similarly low ssh and equatorward transport residuals appear first off central america and mexico in january february before spreading farther north in spring and summer 6 the maximum values of eke occur when each of the boundary currents are maximum

the role of the alaskan stream in modulating the bering sea climate 1 a numerical ocean circulation model with realistic topography but with an idealized forcing that includes only lateral transports is used to study the role of the alaskan stream as in modulating the bering sea bs variability sensitivity experiments each one with a different strength of the as transport reveal a nonlinear bs response an increase of as transport from 10 to 25 sv causes warming 0 25 c mean 0 5 c maximum and sea level rise in the bs shelf due to increased transports of warmer pacific waters through the eastern passages of the aleutian islands but an increase of as transport from 25 to 40 sv had an opposite impact on the bs shelf with a slight cooling 0 1 c mean 0 5 c maximum as the as transport increases flows through passages farther downstream in the western aleutian islands are affected and the variability in the entire bs is reduced transport variations of 0 1sv in the bering strait are found to be correlated with mesoscale variations of the as and associated transport variations in the aleutian islands passages these results have important implications for understanding the observed variations in the bering strait and potential future climate variations in the arctic ocean

predictions and observations of convergence in shallow tunnels case histories in greece abstract convergence of shallow tunnels 30 120 m overburden thickness constructed in greece in different types of rock masses has been assessed as a function of the geological strength index gsi classification predictions of maximum vertical and horizontal convergence during or shortly after tunnel excavation were made using finite element modeling fem and the characteristic line theory and were found to be in good agreement with geodetic observations of convergence collected during a period of approximately 2 months after the section excavation the results from fem were found to adequately and reliably predict the expected deformation during tunnel excavation the theory of the characteristic line on the other hand seems to offer a realistic and reliable upper bound estimate of the convergence

deep currents in the central subarctic pacific ocean abstract sections of closely spaced ctd stations along longs 165 w 175 w and 175 e in combination with 14 month current records from the central longitude define two deep nearly zonal currants with speed increasing upward in the subarctic pacific one flows eastward above the aleutian rise and aleutian trench and appears to be a concentration of geostrophic flow forced by the bottom topography the other flows westward along the aleutian island arc and is the northern boundary current predicted by deep circulation theory both currents reach to the sea surface the boundary current being simply the deep part of the alaskan stream the current records were too few to permit better than rough estimates of volume transports but to the extent that they could be combined with thermal wind calculations they suggest at 175 w 1 a transport of 28 106 m3 s 1 for the alaskan stream of whch 5 106 m3 s 1 was found below 1500 m and 2 a transport of around 20 1o6 m3 s 1 for the eastward jet of wh

travel distance angle for rapid landslides in constructed and natural soil slopes rapid landslides in constructed and natural soil slopes have the potential to cause loss of life destruction of property and damage to the natural environment because the velocity of the slide

land sea linkage of holocene paleoclimate on the southern bering continental shelf detailed diatom records within surface and core sediments from the southern bering continental shelf sbcs reveal that the holocene evolution of sea ice distribution is associated with low pressure patterns holocene sea ice distribution over the sbcs was mainly controlled by the location of the aleutian low the corresponding paleoceanographic and paleoclimate conditions can be divided into three stages 1 the early holocene before 7000 cal yr bp was characterized by extensive sea ice distribution under two low pressure cells which covered the western bering sea and the gulf of alaska respectively 2 between 3000 and 7000 cal yr bp the low pressure system over the gulf of alaska became weak causing total sea ice mass over the sbcs to retreat 3 in the past 3000 years prevailing southwesterly winds over the sbcs due to the developing aleutian low have reduced further sea ice cover on the sbcs these paleoclimatic changes were probably a response to enso variation the timings of water mass exchanges on the sbcs coincided with sea level change along the alaskan peninsula as a result subsequent morphologic alterations have also influenced the paleoceanographic condition of the sbcs the effect of the surface coastal water and bottom marine water on the sbcs intensified about 6000 cal yr bp when sea level increased

post failure mobility of saturated sands in undrained load controlled ring shear tests the undrained shear behavior of soils with progress of shear displacement is essential to the understanding of liquefied slope failures with long travel distance in this paper using a newly devel

interannual variability of temperature inversions in the subarctic north pacific 1 a newly developed ocean reanalysis dataset 1987 2004 has been used to study interannual variability in the temperature inversion that characterizes the upper layer of the subarctic north pacific a local minimum in temperature at the upper edge of the inversion exhibits a significant interannual variability conversely fluctuations in the local temperature maximum tmax found at the lower edge are relatively small in the tmax case the variation in the depth of tmax is significant and is closely related to enso variability our estimate of the adjoint solution shows that during periods when the tmax is located at shallower deeper depths the source water comes from both the gulf of alaska and the kuroshio extension region only from the kuroshio extension region these facts suggest that the depth of tmax is an important indication for diagnostics of the interannual variability of water mass property in the subarctic pacific

recent observations of variability in the western bering sea current system data from two cruises in the western bering sea are presented and examined during spring 1990 conditions were typical and the kamchatka current had a transport of 11 sv on the other hand during fall 1990 this flow had weakened to 6 sv although a strong flow near the komandorski islands occurred various eddylike features were common during both cruises and were particularly developed in fall although some aspects of the flow patterns may be seasonal in nature the major weakening of transport probably represents an interannual change

global observations of large oceanic eddies 1 ten years of sea surface height ssh fields constructed from the merged topex poseidon t p and ers 1 2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean the higher resolution of the merged dataset reveals that more than 50 of the variability over much of the world ocean is accounted for by eddies with amplitudes of 5 25 cm and diameters of 100 200 km these eddies propagate nearly due west at approximately the phase speed of nondispersive baroclinic rossby waves with preferences for slight poleward and equatorward deflection of cyclonic and anticyclonic eddies respectively the vast majority of the eddies are found to be nonlinear

intermediate depth circulation of the indian and south pacific oceans measured by autonomous floats as part of the world ocean circulation experiment 306 autonomous floats were deployed in the tropical and south pacific ocean and 228 were deployed in the indian ocean to observe the basinwide circulation near 900 m depth mean velocities seasonal variability and lateral eddy diffusivity from the resultant 2583 float years of data are presented area averages local function fits and a novel application of objective mapping are used to estimate the mean circulation patterns of mean circulation resemble those at the surface in both basins well developed subtropical gyres twice as strong in the indian ocean as in the pacific feed western boundary currents tropical gyres are separated by eastward flow along the equator in both hemispheres of both basins although the indian subcontinent splits the north indian tropical gyre the antarctic circumpolar current acc and west wind drifts are prominent in both basins generally tending slightly southward but deviating to the north behind the del cano kerguelen and campbell plateaus and of course south america remarkably the eastern boundaries of the southern subtropical gyres in all three basins apparently occur in the ocean interior away from land the indian ocean s subtropical gyre and perhaps part of the south atlantic s reaches east to a retroflection just upstream of the campbell plateau south of new zealand seasonal variability at 900 m is focused around the equator with weaker variability found near certain bathymetric features there is a remarkable agreement between the observed seasonable variability and that predicted by the jet propulsion laboratory jpl estimating the circulation and climate of the ocean ecco data assimilating numerical model aside from seasonal effects eddy variability is greatest along the equator in tropical and subtropical western basins and along the acc integrals of velocity across regional passages tasman sea mozambique channel provide useful reference for hydrographic analyses of transport across whole ocean basins however the uncertainty associated with the appropriate continuity relation for horizontal flow e g geostrophy vs nondivergence is comparable to the mean flow

the anticyclonic baroclinic eddy off sitka alaska in the northeast pacific ocean abstract among the many mesoscale eddies found in the northeast pacific ocean is a well developed anticyclonic baroclinic eddy situated within a few hundred kilometers of sitka alaska 57 n 138 w it has definitely been observed during spring and summer 1958 summer 1960 and summer 1961 observations made at other times show some evidence of its occurrence also the trajectories of three norpax drifting buoys for april may 1977 also indicated the probable presence of an eddy there the eddy whose diameter ranges from 200 to 300 km and whose depth extends to 100 m and probably to as much as 2000 m recurs at the same location the center of the eddy is characterized by the following features the surface water is less saline and only somewhat warmer than at its periphery at depths within and below the halocline it is warmer less saline and contains more dissolved oxygen than at the periphery and a warm core is situated within the halocline the halocline is usually depressed by less than 100 m but

near surface circulation of the northeast pacific ocean derived from woce svp satellite tracked drifters abstract statistics of the near surface circulation in the northeast pacific ocean were derived from the trajectories of nearly 100 surface drifters tracked between august 1990 and december 1995 as part of the world ocean circulation experiment s woce surface velocity program svp drifters were drogued within the mixed layer 15 m drogue depth or near the top of the permanent halocline 120 m all branches of the alaskan gyre were well sampled at both depths revealing a weak subarctic current a bifurcation of the subarctic current near 48 n 130 w at 15 m depth and strong variable flow in the alaska current and alaskan stream at 120 m depth northward flow in the alaska current occurred much farther offshore than within the mixed layer the drifter trajectories revealed interannual variability with evidence of an intensified alaskan gyre during the winters of 1991 92 and 1992 93 and more southerly transport during winter 1994 95 a minimum in eddy kinetic energy was found at both depths within the northern branch of the subtropical gyre eddy kinetic energies were nearly twice as high in the mixed layer compared to below and were 2 3 times larger in winter than in summer throughout most of the near surface alaskan gyre high eddy energies observed near the eastern perimeter of the alaskan gyre may be due to the offshore intrusion of eddies formed by coastal current instabilities taylor s theory of single particle dispersion was applied to the drifter ensembles to estimate lagrangian decorrelation scales and eddy diffusivities both the initial dispersion and random walk regimes were identified in the dispersion time series computed for several regions of both ensembles the integral time scales and eddy diffusivities computed from the dispersion scale linearly with r m s velocity which is consistent with drifter studies from the atlantic an exception is the meridional integral time scales which were nearly constant throughout the study area and at both drogue depths the magnitudes of the derived eddy statistics are comparable to those derived from surface drifters in other parts of the world ocean these are the first lagrangian estimates of particle dispersion over a broad region of the near surface north pacific and the consistency of the results with previous studies from the atlantic lends credence to the idea that the simplifying assumptions of taylor 1921 proceedings of the london mathematical society series a 20 196 221 are reasonably valid throughout the upper ocean this bodes well for the effective parameterization of near surface diffusivities in general circulation models finally the drifter derived velocity statistics were used to speculate on the source regions of waters of possible coastal origin observed at offshore stations during the field studies of the canadian joint global ocean flux study

extreme deformation characteristics and countermeasures for a tunnel in difficult grounds in southern shaanxi china the qingling bashan qb mountain region in southern shaanxi mainly consists of strongly compressive zones from east to west with tight folds and compressive fractures there is a wide distribution of soft rocks of various types such as phyllite and slate accompanied by complex geological structures ironically tunnel construction in these difficult grounds with complicated geological conditions embraces a high risk of extreme deformation due to various unpredictable reasons which can frequently cause collapse and result in budget overruns during the construction period therefore it is crucial to conduct effective countermeasures to eliminate or avoid such adverse impacts this paper provides a case study on the yingfeng tunnel a tunnel constructed in soft rock consisting of a slate ground based on a geological survey indoor experiments and in situ monitoring a successive rock mass deformation resulted in the tunnel lining seriously intruding into construction clearance and some other sections even collapsing during the construction the maximum displacement amount was 62 5 cm while the maximum deformation speed reached as high as 34 18 mm day additionally to evaluate the construction impacts of tunnelling induced geo hazards an investigation on extreme deformation was conducted considering the time dependent features of the rock mass deformation the constraint convergence method was used to put forward applicable countermeasures in this paper finally from the feedbacks of monitoring results extreme deformation of the yingfeng tunnel was effectively controlled

poleward reach of the california undercurrent extension 1 the california undercurrent is known to transport relatively warm high salinity nutrient rich water from the equatorial pacific to vancouver island along the western continental slope of north america this transport helps maintain the high productivity of the eastern boundary california current system in this study we use several decades of water property survey data for the coasts of oregon washington british columbia and alaska to show that equatorial pacific water carried poleward by the undercurrent can eventually reach the aleutian islands roughly 11 000 km from the source region long term current meter records confirm the undercurrent as far north as vancouver island where the current is found to be weakest in spring but then to strengthen through the summer and fall before merging with the wind forced poleward flowing davidson current in winter the core depth of the equatorial water increases from 150 m 25 m off northwest washington near the northern end of the western north america coastal upwelling domain to 225 m 25 m off southeast alaska near the southern end of the gulf of alaska coastal downwelling domain

modeling effects of tidal and wave mixing on circulation and thermohaline structures in the bering sea process studies 1 ocean circulation and the tidal current in the bering sea are simulated simultaneously using a coupled ice ocean model ciom with tidal and parameterized wave mixing to investigate several important physical processes the simulated circulation pattern in the deep basin is relatively stable cyclonic and has little seasonal change the bering slope current is estimated at 5 sv and the kamchatka current at 20 sv the modeled volume transports through the aleutian passes compared reasonably well with observations it is confirmed that subtidal clockwise circulation around st george and st paul islands are driven by tidal rectification the simulation results show that wind wave mixing and tidal stirring are the main factors controlling the formation of the upper and the bottom mixed layers respectively the mechanism of thermocline and the cold pool summer minimum temperature water formation in the middle shelf are investigated in depth the ciom reproduces the cold winter convective water in the middle shelf that forms the bottom cold pool which persists throughout the summer until sea surface cooling and strong wind mixing in fall leading to an unstable vertical water column and eventually to vertically well mixed water in the winter sensitivity experiments show that tidal and wind wave mixing are two important factors in accurately estimating the volume of the cold pool which is the ideal marine habitat for cold water species

investigation and dynamic analysis of the long runout catastrophic landslide at the shenzhen landfill on december 20 2015 in guangdong china at 11 40 a m december 20 2015 a catastrophic landslide occurred in shenzhen guangdong southeast china seventy seven people were killed and 33 buildings were buried or damaged which were in the direct path of the landslide at the guangming new district the landslide involved 2 73 million m3 of the municipal solid waste msw and had a horizontal runout distance of 1100 m over a vertical distance of 113 m which was equivalent to a fahrboschung of 6 and covered an area of 0 38 km2 basic post failure characteristics are described in this study dynamic simulation software danw and rheological models were used to simulate the runout behavior of the displaced landslide material in order to provide information for the hazard zonation of similar types of potential msw landslides the simulated results revealed that a combination of the frictional model and voellmy model is able to provide the best performance in simulating this landslide also the results showed that this landslide had a duration of about 50 s with a maximum velocity of 22 4 m s it was expected that these models and parameters could improve the accuracy of future hazard assessments of areas with geological topographical and climatic features similar to the shenzhen hong ao landfill

flow characteristics of 2 phase granular mass flows from model flume tests abstract changes in basal fluid pressure and normal flow depth in 2 phase granular mass flows the equivalent coefficient of friction and the equivalent coefficient of friction between gravity centres before and after failure were investigated for pumiceous gravel and a mixture of pumiceous gravel and volcanic ash by means of large scale model flume tests the proportion of finer soil particles the inclination of slope segments and the width of horizontal segments were selected as the controlled conditions no excess of basal fluid pressure was observed in the pumiceous gravel on the other hand an excess of pressure head was generated in the mixture of pumiceous gravel and volcanic ash this was due to the suspension of the fine particles in the pore fluid increasing its effective density and the quasi undrained shear deformation due to the low permeability of the mixture in the mass of the granular flow during its motion in tests with a slope of 30 both the pumiceous gravel and the mixture of pumiceous gravel and volcanic ash travelled less distance in the narrow flume than in the wide one this was likely because in the wide flume no clogging occurred where the width of the flume changed and less frictional collisions against side walls and resulting grains contact took place in tests with a narrow flume the pumiceous gravel clogged and most of material was deposited around the constriction however the mixture passed through the constriction smoothly this could be because less frictional resistance was generated in the mixture due to the lowering of effective stress between soil particles associated with the excess of pore fluid pressure although the test on a slope of 35 had the largest potential energy before the release of the materials and the test on a slope of 25 had the least the test with the 35 degree slope produced the largest equivalent coefficient of friction and the smallest value was obtained from the test with a 25 degree slope this finding suggests that the dissipation of kinetic energy especially in the vertical direction due to the collisions and the following abrupt deformation around the connection of the flume between the slope and horizontal segments may play an important role in the travel distance

the influence of an alaskan stream eddy on flow through amchitka pass flow into the bering sea through amchitka pass in the central aleutian islands is shown to respond to the presence of a large meander eddy in the alaskan stream south of the pass maximum flow into the aleutian basin of the bering sea occurs when the eddy center lies nearest to the axis of amchitka pass a conceptual model of low frequency circulation variability within the bering sea based upon results of empirical orthogonal function analyses of sea surface height anomalies measured by the geosat radar altimeter is presented

observations from a yakutat eddy in the northern gulf of alaska 1 the impingement of deep basin eddies on the shelf in the gulf of alaska has been implicated as an important mechanism for cross shelf exchange the influence of eddies on biological processes has been confirmed with data from the sea viewing wide field of view sensor showing elevated chlorophyll associated with eddies altimetry data suggest that an eddy formed in the winter of 2003 near yakutat alaska and propagated along the shelf break reaching the head of the gulf by spring this eddy was sampled during may and september of 2003 the eddy core water was warm salty and high in nitrate relative to basin water of the same density but was similar to historical water properties from the shelf near yakutat this suggests a shelf origin for the eddy core water

interannual variability of the gulf of alaska eddy field 1 regions of high eddy kinetic energy eke in the gulf of alaska goa calculated from altimetry data denote formation regions and translation pathways for eddies high eke is observed along the shelf break in winter and spring with lower values in summer and autumn three regions of high eke are examined in detail in the eastern goa particularly high eke occurred in 1998 in the northwestern goa eddies were observed quasi annually between 1999 and 2004 but were less frequent prior to that time or in 2005 and 2006 eddies northeast of kodiak island have been implicated in high offshelf chlorophyll concentrations observed from ocean color satellites correlations between eke and chlorophyll concentration are significant there suggesting that eke may be valuable for predicting phytoplankton blooms in this region

iron transport by mesoscale haida eddies in the gulf of alaska abstract a two year study of the iron distributions in anticyclonic mesoscale haida eddies of the eastern north pacific ocean has shown that such eddies are a major source of iron to the high nitrate low chlorophyll hnlc waters of the central gulf of alaska basin these eddies which are typically about 100 km in diameter form off the west coast of canada in winter and then track roughly westward into the open ocean therefore they carry large quantities of iron rich coastal waters into iron limited waters of the oligotrophic gyre when the eddies had first formed their dissolved iron concentrations were nearly two orders of magnitude higher than is typically observed at station papa 50 n 145 w 3 n m versus less than 0 05 n m and the total iron in the eddies surface waters 10 40 m was more than 13 n m higher than open ocean waters of the alaska gyre 14 n m versus 0 5 n m while the overall iron content of the eddies decreased rapidly during the first year after they formed the eddy we were able to track the longest still contained 1 5 2 times more iron than the surrounding waters 16 months after its formation therefore although iron concentrations in the surface mixed layers of the eddies drop to levels observed outside very rapidly within 4 months upward transport along isopycnals and upwelling due to eddy decay as well as vertical advective and diffusive transports typical of north pacific waters probably provide steady fluxes of iron into the euphotic zone from the still iron rich eddy core waters throughout the lifetime of the eddy

summer transport estimates of the kamchatka current derived as a variational inverse of hydrophysical and surface drifter data 1 the quasistationary summer bering sea circulation is reconstructed as a variational inverse of the hydrographic and atmospheric climatologies transport estimates through the bering strait and surface drifter data our results indicate the splitting of the kamchatka current in the vicinity of the shirshov ridge this branching is in agreement with independent argo drifter observations it was also found that transport of the kamchatka current gradually increases downstream from 14 sv in the olyutorsky gulf to 24 sv in the kamchatka strait which is twice higher than previous estimates

a quasi geostrophic circulation model of the northeast pacific part ii effects of topography and seasonal forcing abstract a quasi geostrophic regional model of the northeast pacific is used to investigate the effects of bottom topography and seasonal wind forcing on the circulation of the alaskan gyre in a numerical experiment with a flat bottom and steady forcing the most energetic signal is due to mesoscale eddies with a 100 day period associated with barotropic wave propagation along the aleutian island arc bottom topography eliminates this signal and causes the flow fluctuations to be of lower frequency and primarily in the first baroclinic rather than the barotropic mode experiments with a climatological seasonal cycle in the wind field show that bottom topography has an important influence in moderating the intensity of the seasonal response it is suggested that the very substantial seasonal variations of the alaskan gyre transport obtained in previous numerical studies of the ne pacific are due to the failure of these models to include or to resolve adequately the bottom topography

mimoc a global monthly isopycnal upper ocean climatology with mixed layers a monthly isopycnal mixed layer ocean climatology mimoc global from 0 to 1950 dbar is compared with other monthly ocean climatologies all available quality controlled profiles of temperature t and salinity s versus pressure p collected by conductivity temperature depth ctd instruments from the argo program ice tethered profilers and archived in the world ocean database are used mimoc provides maps of mixed layer properties conservative temperature absolute salinity sa and maximum p as well as maps of interior ocean properties sa and p to 1950 dbar on isopycnal surfaces a third product merges the two onto a pressure grid spanning the upper 1950 dbar adding more familiar potential temperature and practical salinity s maps all maps are at monthly 0 5 0 5 resolution spanning from 80 s to 90 n objective mapping routines used and described here incorporate an isobath following component using a fast marching algorithm as well as front sharpening components in both the mixed layer and on interior isopycnals recent data are emphasized in the mapping the goal is to compute a climatology that looks as much as possible like synoptic surveys sampled circa 2007 2011 during all phases of the seasonal cycle minimizing transient eddy and wave signatures mimoc preserves a surface mixed layer minimizes both diapycnal and isopycnal smoothing of s as well as preserves density structure in the vertical pycnoclines and pycnostads and the horizontal fronts and their associated currents it is statically stable and resolves water mass features fronts and currents with a high level of detail and fidelity

thermohaline structure in the california current system observations and modeling of spice variance 1 upper ocean thermohaline structure in the california current system is investigated using sustained observations from autonomous underwater gliders and a numerical state estimate both observations and the state estimate show layers distinguished by the temperature and salinity variability along isopycnals i e spice variance mesoscale and submesoscale spice variance is largest in the remnant mixed layer decreases to a minimum below the pycnocline near 26 3 kg m 3 and then increases again near 26 6 kg m 3 layers of high low meso and submesoscale spice variance are found on isopycnals where large scale spice gradients are large small consistent with stirring of large scale gradients to produce smaller scale thermohaline structure passive tracer adjoint calculations in the state estimate are used to investigate possible mechanisms for the formation of the layers of spice variance layers of high spice variance are found to have distinct origins and to be associated with named water masses high spice variance water in the remnant mixed layer has northerly origin and is identified as pacific subarctic water while the water in the deeper high spice variance layer has southerly origin and is identified as equatorial pacific water the layer of low spice variance near 26 3 kg m 3 lies between the named water masses and does not have a clear origin both effective horizontal diffusivity h and effective diapycnal diffusivity v are elevated relative to the diffusion coefficients set in the numerical simulation but changes in h and v with depth are not sufficient to explain the observed layering of thermohaline structure

modelling the generation of haida eddies abstract a numerical model forced with average annual cycles of climatological winds surface heat flux and temperature and salinity along the open boundaries is used to demonstrate that haida eddies are typically generated each winter off cape st james at the southern tip of the queen charlotte islands of western canada annual cycles of sea surface elevation measured at coastal tide gauges and topex poseidon crossover locations are reproduced with reasonable accuracy model sensitivity studies show that haida eddies are baroclinic in nature and are generated by the merging of several smaller eddies that have been formed to the west of cape st james the generation mechanism does not require the existence of instability processes and is associated with the mean advection of warmer and fresher water masses around the cape from hecate strait and from the southeast these advected water masses generate plumes of buoyant flow which intensify and sustain small patches of anticyclonic circulation immediately to the northwest of the cape when the flow is stronger several of these smaller eddies can merge to generate a larger eddy the haida eddy similar to observations a typical generation shedding cycle for larger haida eddies in the model is 3 4 months consistent with previous in situ water property measurements these experiments show that the eddies are generally comprised of mixed layer water from hecate strait queen charlotte sound and the continental shelves off northern vancouver island their vertical extent during the mature stage is roughly 1000 m

vertical velocity estimates in the north pacific using argo floats abstract vertical velocity in the oceans is critical for maintenance of the structure of the main thermoclines and the transport of nutrients from deepwater towards the surface and thus is an important variable for understanding the dynamics of the ocean and the transport of scalar variables in the mid 1970s the author was engaged in discussions with tom rossby about how sofar floats might be used to observe the vertical component of velocity this paper in some sense follows on from those discussions almost 40 years later in this paper the argo array is used to compute the horizontal volume divergence in a control volume in the north pacific divergence is found and this must be related to a volume flux through the base of the control volume the implied vertical velocity is large and various tests are proposed to determine whether or not the estimate is plausible the first test shows that a vertical velocity this large is necessary to close the salt budget the second test shows that the vertical velocity balances about half of the observed heat divergence the remainder is then accounted for by heat flux at the sea surface finally the time variable vertical velocity is computed and used to compute the evolution of the salt content in the control volume thus though the estimated vertical velocity is surprisingly large it passes plausibility tests

modification of a kenai eddy along the alaskan stream 1 a kenai eddy was studied through analyses of satellite altimeter data and hydrographic data from shipboard and argo float observations this eddy formed in december 2006 south of the kenai peninsula and propagated southwestward along the alaskan stream the eddy held horizontally uniform warm core water in january 2007 in late winter 2007 this core water was cooled from the top and a subsurface temperature maximum was formed around 26 5 two years later in summer 2009 warm and low dissolved oxygen low do water characterized by a temperature maximum around 26 5 was observed again in the eddy core and was likely the remnant of original core water at the same time cold and high do water intrusions occurred in the eddy core suggesting that strong modification of core water was ongoing after summer 2009 the core water was fully changed through interaction with another eddy

remotely propagating salinity anomaly varies the source of north pacific ventilation abstract the dense shelf water dsw produced in the sea of okhotsk causes the deepest ventilation in the north pacific and plays a key role in overturning to the depth of intermediate layers salinity determines the density of dsw in cold seas such as this however the variability of dsw salinity has yet to be quantified and its causes remain unknown because of the paucity of available observation data here we describe the variability of dsw salinity in the period from 1950 to 2005 through the analysis of a newly compiled hydrographic dataset expanded with russian measurements in the sea of okhotsk and the bering sea dsw salinity exhibits a decreasing trend of 0 0024 0 0015 y 1 over 1950 2005 in addition to decadal scale variability with a typical magnitude of 0 1 we have found that dsw variability is controlled largely by surface salinity anomalies that propagate along pathways associated with ocean currents from the bering sea to the sea of okhotsk these salt pathways can be traced farther upstream to the alaskan stream and western subarctic gyre we suggest that this is a possible pathway which consists of a previously undefined upper branch of the north pacific overturning cell along this pathway the effects of the nodal tide that has an 18 6 year period may also propagate from the kuril straits and the aleutian passes our results indicate that long term atmospheric variations and enhanced hydrological cycles over the north pacific which are associated with global climate changes are conducted to the intermediate layer through surface salt pathways and subsequent dsw ventilation and lead to variability in material circulation and biogeochemical cycles

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

diatoms as paleoenvironmental proxies for seasonal productivity sea ice and surface circulation in the bering sea during the late quaternary abstract diatom assemblages in suspended particulate matter spm surface sediments and piston core samples in the southern bering sea and the western subarctic pacific were examined the distribution of diatom assemblages in the southern bering sea shows not only differences in species composition between the spm and surface sediment samples but also preferential dissolution of different species in the upper water column or surface sediments furthermore we present the downcore profiles of selected diatom taxa for four piston cores to indicate changes in paleoceanographic conditions e g seasonal productivity sea ice and surface water circulation of the glacial and deglaciation periods during the late quaternary in particular we propose five models for the annual cycling of the water masses in the western subarctic pacific and the southern bering sea during the late quaternary significant regional differences in diatom accumulation rates and taxonomic composition between the southern bering sea and the western subarctic pacific reflect spatial shifts in water masses caused by the variable extent of sea ice cover and cold low salinity surface waters in these regions

the shedding of mesoscale anticyclonic eddies from the alaskan stream and westward transport of warm water abstract the south flowing waters of the kamchatka and oyashio currents and west flowing waters of the alaskan stream are key components of the western sub arctic pacific circulation we use ctd data argo buoys woce surface drifters and satellite derived sea level observations to investigate the structure and interannual changes in this system that arise from interactions among anticyclonic eddies and the mean flow variability in the temperature of the upstream oyashio and kamchatka currents is evident by warming in mesothermal layer in 1994 2005 compared to 1990 1991 a major fraction of the water in these currents is derived directly from the alaskan stream the stream also sheds large anticyclonic aleutian eddies averaging approximately 300 km in diameter with a volume transport significant in comparison with that of the kamchatka current itself these eddies enclose pools of relatively warm and saline water whose temperature is typically 4 c warmer and salinity is 0 4 greater than that of cold core kamchatka eddies in the same density range aleutian eddies drift at approximately 1 2 km d 1 and retain their distinctive warm and salty characteristics for at least 2 years selected westward pathways during 1990 2004 are identified if the shorter northern route is followed aleutian eddies remain close to the stream and persist sufficiently long to carry warm and saline water directly to the kamchatka current this was observed during 1994 1997 with substantial warming of the waters in the kamchatka current and upstream oyashio if the eddies take a more southern route they detach from the stream but can still contribute significant quantities of warm and saline water to the upstream oyashio as in 2004 2005 however the eddies following this southern route may dissipate before reaching the western boundary current region

recent variability in the pacific western subarctic boundary currents and sea of okhotsk abstract the objective of this research is to describe physical processes which are the cause of the recent variability of the pacific western subarctic waters rapid thermohaline changes have occurred within the oyashio and kamchatka current during the last decade this variability has included a warming of the kamchatka current warm intermediate layer but a cooling and freshening of the upper layer in the oyashio and sea of okhotsk the example presented here uses data obtained during the canada russia inpoc and woce projects as well as the new russian studies with high resolution station grid the possible physical mechanism that generated the upper layer freshening during the thermohaline transition is examined major components of the fresh water budget of the okhotsk sea are considered in order to describe the dramatic changes in salinity which have recently occurred in the pacific subarctic significant changes in precipitation and other fresh water inputs are demonstrated it is suggested that upper layer of the oyashio and kamchatka current became cooler and fresher because of the export of cold fresher waters from the bering and okhotsk seas these waters from the marginal seas have cooled the bottom of the halocline reducing evaporation and acting as a feedback that has kept the upper layer of the western subarctic boundary currents fresh it is also shown that the outflow of the cold sea of okhotsk water has changed its path during this recent thermohaline transition

liquefaction flowslides in rocky mountain coal mine waste dumps over the past 25 years there have been a large number of long runout flowslides from rocky mountain coal mine waste dumps the waste dumps are constructed as end dumped fills with an angle of repos

zonal evolution of alaskan stream structure and transport quantified with argo data the alaskan stream as flows west southwestward along the south side of alaska and the aleutian island arc a western boundary current at the northern edge of the north pacific subpolar gyre the argo float array has improved sampling of the gulf of alaska allowing quantification of the as s zonal evolution from 140 w to 175 w geostrophic alongshore transport of the as in the upper 1000 dbar referenced to an assumed level of no motion at 1000 dbar shows little change from east to west however alongshore absolute geostrophic transports in the top 2000 dbar obtained by combining mean absolute 1000 dbar velocities from float displacements with the geostrophic velocity fields generally increase to the west we estimate full depth transports by fitting a barotropic and the first two baroclinic modes calculated from a climatology to the absolute geostrophic velocities in the upper 2000 dbar and applying the velocities from these fits from 2000 dbar to the seafloor flowing west from its formation region at 140 w 145 w the full depth as becomes stronger more barotropic and also narrower once it reaches 160 w with along shore transports increasing from 16 4 4 9 sv 1 sv 106 m3 s 1 at 140 w to 32 6 5 2 sv at 175 w mean concentrations of relatively warm salty oxygen poor and nutrient rich pacific equatorial water pew in the as decrease from 17 8 0 3 to 8 5 0 5 between 140 w and 175 w however the volume transport of pew by the as exhibits little change over the pew density range between these longitudes

satellite and hydrographic observations of eddy induced shelf slope exchange in the northwestern gulf of alaska 1 satellite and hydrographic observations of oceanographic conditions in the northwestern gulf of alaska indicate that anticyclonic eddies propagating adjacent to the continental shelf alter the structure of the shelf break front and in doing so influence the shelf slope exchange of biota and water mass properties eddies typically form in the northern gulf of alaska during fall and winter and propagate southwestward within an 200 km wide corridor along and above the continental slope eddy activity within this corridor diminishes in the downstream direction the trajectories of faster propagating 4 km day eddies tend to lie closer to the shelf break than do the trajectories of slower propagating 1 5 km day eddies the interaction between azimuthal eddy currents and the shelf break frontal jet 1 establishes an upwelling zone associated with the leading flank of the eddy that strengthens cross slope gradients 2 weakens cross slope gradients and promotes shelf slope exchange where the eddy is adjacent to the shelf and 3 reestablishes a weak upwelling zone associated with the trailing flank of the eddy

estimation of in situ stress along deep tunnels buried in complex geological conditions abstract the headrace tunnels of the jinping ii hydropower station are 16 7 km in length and have a maximum depth of 2525 m many difficulties have been encountered in estimation of virgin rock stresses along the tunnels one method was presented including the macroscopic analysis of the region geological structures and topography and the integrated analysis of in situ stresses based on the multi source information in local tunnel sections the characteristics of geological structures and tectonic movement were studied to determine the orientations of the tectonic stresses within the jinping ii tunnel project region the influences of the topography on the distribution of in situ stress were analyzed using numerical methods the virgin stress regimes were preliminarily estimated based on the geological and topographical analysis and the world stress map under the guidance of these results multi source information was collected regarding rock brittle failures edzs core disking and large scale deformation of soft rock several techniques were adopted including multivariate regression numerical simulation and stereographic projection an iterative method for the orientations and magnitudes of in situ stresses is presented the in situ stress regimes orientations and magnitudes in tunnel sections of different depths were obtained and verified they can provide the basic conditions for analysis of the stability of surrounding rock mass during excavation

on slope instability induced by seepage erosion this paper is focused on seepage erosion causing liquefaction processes and rapid slope failures one case history which occurred along an old fluvial terrace in the po plain northern italy is

trace metal distributions within a sitka eddy in the northern gulf of alaska in the northern gulf of alaska mesoscale anticyclonic eddies have been implicated as a mechanism of the cross shelf exchange of iron fe replete coastal waters with fe deplete subarctic alaskan gyre waters based on existing hydrography and macronutrient distributions a sitka eddy sampled during august 2007 is divided into a surface eddy core a shallow subsurface eddy core and a deeper subsurface eddy core the distributions of aluminum al manganese mn and fe in the eddy are examined and compared to distributions at shelf stations similar to where the eddy formed as well as basin stations representative of the fe limited subarctic alaskan gyre relative to basin stations dissolved and particulate al and dissolved mn were elevated in eddy core waters reactive fe concentrations within the shallow subsurface eddy core were nearly seven times greater than reactive fe concentrations at similar densities at the basin stations this shallow subsurface eddy core is likely mixed into the euphotic zone during storm induced mixing as well as mixing during isopycnal relaxation as an eddy dies out the flux of reactive fe to surface waters from the shallow subsurface core of eddies in the gulf of alaska is a significant source compared to both remote and local atmospheric dust deposition it is hypothesized that fe supply from eddies in the eastern gulf of alaska shifts the core of the high nutrient lower than expected chlorophyll water farther west in conjunction with an eddy desert in that same region

the shedding of an anticyclonic eddy from the alaskan stream as observed by the geosat altimeter the evolution of a meander into an anticyclonic eddy which separates from the alaskan stream in the vicinity of the central aleutian islands is observed in two years of sea surface height anomalies computed from geosat exact repeat mission altimeter data the trajectory of the center of mass is estimated using a modified perpendicular bisector method eddy separation is inferred to occur where the trajectory makes a distinct turn to the southwest the observed region of meander growth and eddy separation agrees with that predicted by theory the evolution of meander eddy height and radius is estimated from least squares fits of the data to an axially symmetric gaussian profile the heights and radii are used to calculate the strength vorticity and energetics of the meander eddy ekman dynamics are assumed to govern the eddy decay spin down times based on vorticity are much longer than those based on energetics this is consistent with an eddy s ability to maintain its integrity as it decays representative height diameter and velocity scales of the eddy are characteristic of rings spawned by other current systems assuming a ring structure for this eddy the estimated ring volume represents a 21 transport anomaly referenced to the mean annual transport into the bering sea

the north pacific climatology of winter mixed layer and mode waters abstract a climatology of the winter mixed layer in the north pacific ocean was constructed using hydrographic data from historical archives and recent observational programs including the world ocean circulation experiment the main aim was to provide better knowledge about source areas of upper water masses the authors have endeavored to preserve water properties near the frontal regions by keeping the smoothing scale as small as possible the resulting climatology shows considerable differences in the mixed layer depth and its water properties from those derived from the world ocean atlas woa maps of the potential vorticity field of the north pacific pycnocline are presented using the isopycnally averaged climatology hydrobase three distinct lateral minima of potential vorticity are identified as subtropical mode water stmw central mode water cmw and eastern subtropical mode water estmw in the western central and eastern parts of the subtropical gyre respectively the hydrobase isopy

multi year meanders and eddies in the alaskan stream as observed by topex poseidon altimeter the birth life and decay of long lived anticyclonic eddies or meanders in the alaskan stream are observed from topex poseidon t p satellite their surface height anomalies approach 72 cm average diameter is about 160km and they live for 1 to 3 years propagating along the stream with mean speed of 2 5 km d 1 of the six observed the last three were formed after the first t p observations in september 1992 of these two evolved from eddies near alaskan panhandle in winter drifting across the northern gulf of alaska before entering the alaskan stream while another formed in the stream west of shelikof strait

rhizoplegma boreale radiolaria a tracer for mesoscale eddies from coastal areas 1 the impact of mesoscale eddies on the production of radiolarian species rhizoplegma boreale in the central subarctic pacific was investigated through analysis of sinking particle fluxes collected using sediment trap and altimetry data from satellite observations altimetry observations provided the locations of mesoscale eddies in time and space and indicated that mesoscale eddies propagating around sediment trap station sa were closely related to the high r boreale fluxes at the station the mesoscale eddies likely provided the deep sea region of the central subarctic pacific with coastal nutrient rich waters derived from the region around the aleutian islands and influenced the productivity of microzooplankton groups at station sa

seasonal cycles of nutrients and dissolved inorganic carbon at high and mid latitudes in the north pacific ocean during the skaugran cruises determination of new production and nutrient uptake ratios abstract the results of a 2 yr monitoring program in the north pacific march 1995 april 1997 using the commercial cargo carrier m v skaugran are presented in this paper seasonal changes in macronutrients nitrate phosphate and silicate dissolved inorganic carbon dic and total alkalinity ta were recorded in the surface waters of 12 major provinces of the north pacific ocean 35 55 n north of the subarctic boundary 40 n nitrate rarely decreased to below detection limit except in the more near shore provinces with nitrate concentrations remaining as high as 8 9 mol kg 1 in the summer in the northern provinces of the bering sea the central and western subarctic pacific there were also strong latitudinal nutrient gradients in most provinces of the subarctic pacific there was little interannual change in the nutrient cycles except in the western subarctic pacific where nitrate concentration fell to 2 6 mol kg 1 in the summer of 1996 we suggest that this large nitrate depletion was due to enhanced diatom production triggered by the supply of iron from the asian continent the relationship between salinity normalized ta and dic revealed that calcification was low or negligible in the surface waters of the bering sea and the western subarctic pacific in contrast the percent of caco 3 production to organic carbon production was found to be at times as high as 70 75 in the eastern subarctic pacific and the southern region off east japan this study also revealed east west contrasts in the seasonal nutrient depletion ratios in the east the elevated dic no 3 ratios and low si oh 4 no 3 ratios were due to high caco 3 production and low diatom production in surface waters on the contrary in the western subarctic pacific and the bering sea the low redfieldian dic no 3 ratios and the high si oh 4 no 3 ratios were due to low calcification and high diatom production the annual new production was estimated from the seasonal drawdown of nitrate at the surface it ranged from 10 1 g c m 2 yr 1 in the subtropical gyre to 76 83 g c m 2 yr 1 in the western subarctic pacific overall horizontal advection was the major source of uncertainty in the estimation of new production finally the net removal of carbon from the surface by the biological pump was then estimated to be 0 58 gt c yr 1 north of 35 n in the pacific ocean the subarctic north pacific and the bering sea accounted for 93 of the carbon removal

impact of haida eddies on chlorophyll distribution in the eastern gulf of alaska mesoscale haida eddies influence the distribution of surface phytoplankton in the eastern gulf of alaska through two processes enhanced productivity in central eddy water and seaward advection of highly productive coastal waters in the outer rings of eddies these two processes were observed in a sequence of monthly images over five years for which images of seawifs derived chlorophyll distributions were overlaid by contours of mesoscale sea surface height anomaly derived from topex and ers 2 satellite observations satellite measurements were supplemented with ship based chlorophyll observations through one of the eddies haida eddies are deep anticyclonic mesoscale vortices that normally form in winter and early spring near the southwest coast of the queen charlotte islands high levels of chlorophyll observed in eddy centres indicated that they supported phytoplankton blooms in spring of their natal years with timing of these blooms varying from year to year and exceeding in magnitude the chlorophyll concentrations of surrounding water elevated chlorophyll levels also were observed in eddy centres in late summer and early autumn of their natal year enhanced chlorophyll biomass is attributed to higher levels of macro nutrients and higher levels of iron enclosed within eddies than in surface deep ocean water by late spring and summer when coastal water supported higher chlorophyll biomass than did oceanic offshore regions eddies that straddled the continental margin entrained high chlorophyll coastal water into their outer rings and carried it several hundred kilometres into the gulf of alaska along their southern sides on some occasions a deep ocean eddy would entrain chlorophyll from an adjacent eddy located closer to the coast forming a conveyor belt transport process to inject coastal biota into the deep sea region of the gulf this process extended the coastal region of high chlorophyll surface water and therefore phytoplankton rich water several hundred kilometres seaward and dominated the shelf to deep ocean exchange of chlorophyll from late winter to the following autumn

rapid thermohaline transition in the pacific western subarctic and oyashio fresh core eddies seven years of conductivity temperature depth data enable direct computations of volume transport and a description of the temporal changes of water properties in the western subarctic pacific the cooling of the western subarctic surface layer is shown through the observation of the thermohaline transition which occured in the western subarctic during 1990 1997 its main consequences were changes of the oyashio path and restratification of the western subarctic water the example presented here uses data obtained during the canada russia international north pacific ocean climate study as well as the russian project subarctic to show that a warming and ventilation of the midlayers of the western subarctic 200 1000 dbar occurred because of the influx of warm subtropical waters to the oyashio and sea of okhotsk and to the weak coastal oyashio before the transition this influx appears to have reversed in the early 1990s now subarctic intermediate waters displace the remnants of subtropical waters that penetrated to the sea of okhotsk through the soya strait and create strong stratification in the oyashio area this transition appears to have begun during the reinforcement in the coastal oyashio

what is the contribution of time dependent deformation in tunnel convergence tunnel excavation produces stress changes to the ground and strain to the support lining leading to the closure convergence or instability of the excavated area convergence recorded after section excavation is assigned to i strain resulting from the progressive tunnel front advance face advance effect and ii the time dependent properties of the soil material ground creep effect in the present study based on the geodetic monitoring records of two recent road tunnels in greece a simple methodology to estimate the contribution of each of the two effects is presented our analysis reveals that at least half of the total deformation of the examined tunnel sections is due to ground creep indicating that the major portion of tunnel deformation is due to the time dependent properties of the ground a result supported by previous studies from other tunnels as well

aleutian basin of the bering sea thermohaline oxygen nutrient and current structure in july 1993 an overview is given of the surface to bottom thermohaline oxygen nutrient and baroclinic flow structures in the aleutian basin of the bering sea and the adjacent north pacific based on high resolution field measurements in july 1993 a basic four layer vertical structure is observed in the upper 1500 m the 30 m top layer is warm low in salinity and nutrients and high in oxygen beneath it a 100 to 150 m thick temperature minimum layer is found believed to be a remnant of winter convection this is followed by a 300 m thick warm layer in which the main halocline oxycline and nutricline are located below it lies a layer of minimum oxygens and maximum nitrates and phosphates centered at a depth of 900 m in the bering sea but rising to 400 m south of the aleutians this basic structure is disrupted in the vicinity of amchitka pass due to strong tidal mixing the deep and abyssal waters of the aleutian basin differ substantially from those at comparable depth in the adjacent pacific by being warmer 0 1 c less saline 0 01 less dense 0 01 kg m3 poorer in oxygen 50 mol kg and richer in silicates 80 mol kg nitrates 1 0 mol kg and phosphates 0 3 mol kg the highest silicate concentrations 240 mol kg occur at the foot of the bering shelf unusual hydrographic conditions exist in an isolated tidal mixing basin in amchitka pass where the bottom mixed layer is 600 m thick 0 7 c warmer 0 14 less saline and 21 mol kg less oxygenated than at comparable depths outside baroclinic currents indicate strong deep jetlike flows on both sides of the aleutian ridge weak shallow eddies in the middle of the aleutian basin and somehat enhanced flows near the bering shelf edge the alaska stream in july 1993 was 100 km wide had a double core with a top speed of 0 54 m s and had a westward volume transport of 38 sv with 14 sv below 1000 dbar the north aleutian current had a speed of 0 2 m s and an eastward transport of 10 sv with 4 sv below 1000 dbar off the bering slope both eastward and westward flows were observed with volume transports near 7 sv

formation and variation of temperature inversions in the eastern subarctic north pacific 1 hydrographic data from profiling float observations for 2001 2005 and from expendable bathythermograph observations for 1993 2005 were analyzed to study the formation and variation of temperature inversions t inversions in the eastern subarctic north pacific snp the formation and variation of t inversions differed significantly between the northern and southern regions of the eastern snp in the northern region the temperature minimum t min at the top of t inversions outcropped to the sea surface and was cooled in the mixed layer nearly every winter this process caused a seasonal cycle in the magnitude of t inversions t with a maximum in winter in the southern region the winter t min outcropped relatively infrequently and the t did not exhibit a significant maximum in winter during most years the t min in the southern region was likely to outcrop upstream near the date line roughly one year earlier and was then advected to the southern region

characteristics of seismic disasters and aseismic measures of tunnels in wenchuan earthquake over the past few years accompanied by big and frequent earthquakes more attention was paid to the tunnel earthquake resistance to reduce tunnel seismic damage and explore the reasonable aseismic measures the tunnel earthquake disaster investigation was employed to analyze and summarize the tunnel seismic damage on the basis of wenchuan earthquake fifty two tunnels near the epicenter of sichuan province were investigated only 7 tunnels did not show structure damage 6 tunnels suffered the most serious damage and the rest appeared damage to various extents it indicates that most serious seismic damage happens to fault fracture zone followed by entrance and common section of the tunnel additionally the results display that the typical seismic damage of tunnels is lining cracking collapsing dislocation construction joints cracking and uplifting of invert and usually lining cracking and collapsing account for a larger proportion therefore the tunnel aseismic design should emphasize the fault fracture zone and tunnel entrance tunnel design should adopt the composite lining structure with shock absorber and whole chain alternative grouting to prevent the lining cracking and collapsing in the seismic fortification zone

undrained shear behaviour of sands subjected to large shear displacement and estimation of excess pore pressure generation from drained ring shear tests undrained shear behaviour of fine silica and weathered granitic sand subjected to large shear displacement is examined parallel experiments using ring shear and the triaxial compression tests on soil specimens through a wide range of initial void ratios were conducted to investigate undrained shear strength as the key factor in the flow like motion of landslides the steady state undrained shear strengths achieved in ring shear tests were in general smaller than those in the triaxial compression tests probably because of the excess pore pressure generation by grain crushing within the shear zone that occurred in ring shear very low steady state shear strengths were achieved however in triaxial compression tests on the dense silica sand in which well defined shear surfaces developed in the cylindrical specimens in these triaxial compression tests shear deformation must have been concentrated on these surfaces to generate excess pore pressure similar to that found in ring shear tests an attempt wa

induced deformation during tunnel excavation evidence from geodetic monitoring abstract during tunnel excavation convergence i e a tendency for reduction of the section area of the void formed is observed due to the stress redistribution around the excavation free surface this deformation accumulates with a gradually decreasing rate until an equilibrium level is obtained its amplitude depends on the rock mass conditions the support system and the excavation procedure as well as on the state of stress and is usually recognized as a two dimensional effect i e a deformation confined to a plane normal to the tunnel axis not affecting neighboring sections in the last years electronic theodolites a new generation of geodetic instruments which can describe in detail the 3 d changes in the shape of tunnels during their excavation stage relative to fixed reference frames became available making possible the understanding of the detailed pattern of such changes especially the effect of rejuvenation of deformation in previously stabilized sections while tunnel excavation is progressing analysis of geodetic monitoring records of certain recently constructed tunnels indicates that occasionally large deformation from specific source sections is transferred along the tunnel axis to host neighboring sections causing additional time delayed deformation of previously stabilized sections and necking of the tunnel this induced deformation is not due to effects such as nearby excavations changes in the hydrological conditions etc and to tertiary creep its distribution along the tunnel axis seems to depend on the potential of host sections to accommodate additional stresses from neighboring deformation source sections and it may lead to a progressive domino type failure the overall process is reminiscent of the triggering of new earthquakes by coulomb static stress changes caused by a certain earthquake on the condition that the stress level in the epicentral areas of the new events was close to the rupture limit

numerical evaluation of a yielding tunnel lining support system used in limiting large deformation in squeezing rock large deformation in squeezing soft rock is a significant challenge that complicates the safety of underground construction engineering a yielding tunnel support system allows a certain amount of over excavation thereby accommodating large deformation in severely squeezing rock in this study a special yielding support system has been developed with a type of newly developed foamed concrete material which has a cushion effect the special yielding support uses pre cast foamed concrete blocks which are mounted in the primary lining and an in situ cast foamed concrete layer which is placed between the primary lining and the secondary lining the effect of the special yielding support on squeezing rock tunnels has been validated by comparing the numerical results with those of a lining strengthened stiff support system the incorporation of the foamed concrete blocks can both reduce the maximum and minimum principal stress in the primary lining relative to the stiff support the maximum and minimum principal stress in the primary lining are about 50 and 60 of those of the stiff support respectively thereby improving the stress state of the primary lining further compared with that in the stiff support the plastic zone in the secondary lining in this yielding support is significantly improved and the deformations at the roof and the sides of the secondary lining are 40 and 46 less than that of the stiff support respectively resulting in a better stress state and less deformation in the secondary lining

low frequency isopycnal variability in the alaska gyre from argo abstract the deployment of a large number of argo floats in the northeast pacific ocean since 2001 has led to a great increase in the volume of data available to study the regional variability on interannual to decadal time scales in this paper gridded fields of hydrographic data from argo are used to examine the low frequency variability of representative isopycnal surfaces over the alaska gyre in the eastern subpolar north pacific anomalies in the depth of isopycnal surfaces and spice anomalies on these surfaces are considered over the 14 year period 2004 2017 an eof analysis is used to characterize the variability occurring at large scales over the region the leading mode of isopycnal depth anomalies through the upper 1000 m of the water column is found to be related to the pacific decadal oscillation the response of a stochastic climate model driven by local ekman pumping is shown to give a reasonable account of variability in the depth of the shallow main pycnocline over the alaska gyre although ocean dynamics must play a role in shaping the spatial response to the wind forcing evidence is presented for counter propagating isopycnal depth anomalies in the subarctic current at the depth of the main pycnocline propagation is dominated by disturbances that are advected eastward by the mean flow at greater depths isopycnal depth anomalies propagate westward at approximately twice the speed of first mode long baroclinic rossby waves consistent with the propagation of rossby waves seen in altimetric observations of sea surface height variability the eastward advection of spice anomalies is also evident in the upper ocean however the dominant signal in the record is a large scale positive spice anomaly that forms locally on subsurface isopycnals evidence is presented that this anomaly arises mainly from the downward diffusion across the pycnocline of heat associated with the marine heatwave of 2013 14 over the northeast pacific the extent to which anomalies are generated locally may limit the potential for decadal prediction of upper ocean conditions over the region

flowslides in stockpiled coal abstract occasional deep seated flowslides in coking coal stockpiles at the north queensland port of hay point are described the flowslides result from particularly loose placement of the light cohesionless material and saturation of the lower levels of the stockpile due to rainfall infiltration and initial moisture at placement consolidated undrained triaxial testing has been used to define the density stress conditions at which liquefaction occurs the flowslide mechanism field verification and preventative measures are briefly discussed