limit equilibrium computation of dynamic passive earth pressure few solution techniques exist for the determination of pseudostatic dynamic passive earth pressures for cohesionless soils the widely accepted mononobe okabe equation can result in the computing of unconservative values if the wall interface friction angle is greater than half the soil internal friction angle as an alternate solution equilibrium equations were formulated assuming a log spiral failure surface and a research computer program was written to calculate the dynamic passive earth pressure coefficient the primary purpose of this paper is to present a comparison of results obtained using the mononobe okabe equation with those obtained using the log spiral formulation key words pseudostatic dynamic passive earth pressure

palaeoclimatic implications of the occurrence of the arcoid bivalve anadara trapezia deshayes in the quaternary of australasia abstract the arcoid bivalve anadara trapezia deshayes 1840 is a eurythermal estuarine mollusc that flourishes at present in eastern australia between port phillip bay victoria and townsville in northern queensland a trapezia first appeared in the australian quaternary fossil record during oxygen isotope stage ois 7 in new zealand where it is now extinct the earliest known occurrences are in the rangitawa fossil beds and in uppermost castlecliffian strata west of wanganui north island ois 11 ca 400 ka the species had an extensive distribution during the last interglacial maximum ois 5e in both australia and new zealand and appears to have had a slightly wider than present geographic range in southeastern australia during the middle holocene as shown by records from tasmania and western victoria where it no longer lives apart from an isolated population inhabiting oyster harbour western australia a trapezia has not been confirmed living in coastal waters west of port phillip bay victoria it became extinct in new zealand sometime after ois 5e the extensive distribution and abundance of a trapezia and other fauna of subtropical affinity during the last interglacial maximum in areas where both are now extinct appears to be associated with an enhanced leeuwin current at that time coinciding with higher less seasonally concentrated levels of precipitation and river discharge the arrival of a trapezia in australasian coastal waters may have been a consequence of planktonic dispersal from southern south america a bravardi del rio from the middle miocene puerto madryn formation on the valdes peninsula argentina may be a possible ancestor for a trapezia

history of stage 5 sea level in bermuda review with new evidence of a brief rise to present sea level during substage 5a abstract oxygen isotope substage 5e is represented by the devonshire formation in bermuda the occurrence of these coastal marine deposits to about 5 m indicates pleistocene sea level data in bermuda do not need tectonic corrections a few published u series coral dates suggest that a conglomerate spencer s point formation may have formed during substage 5c geologic mapping however indicates that the eolianite beneath the conglomerate is pre rather than post devonshire formation in age as was previously thought and the aminostratigraphy of marine sheels also confirms the correlation of the spencer s point and devonshire formations substages 5c and 5a are represented by the southampton formation large eolianites comprise the bulk of this formation they are onlapped by a few small younger marine 1 m and eolian deposits aminostratigraphy confirms that these late southampton age deposits are significantly younger than the devonshire formation and u series dates indicate a substage 5a age the setting of some of these deposits along a protected shoreline precludes discounting their position as anomalous due to large storms this evidence that sea level in bermuda was at about present datum late in substage 5a agrees with interpretations of neotyrrhenian deposits of mediterranean shorelines but not with inferences from the deep sea oxygen isotope record or with data from uplifted coral reefs

seismic passive resistance in soils for negative wall friction in the presence of pseudo static seismic forces passive earth pressure coefficients behind retaining walls were generated using the limit equilibrium method of analysis for the negative wall friction angle case i e the wall moves upwards relative to the backfill with logarithmic spirals as rupture surfaces individual density surcharge and cohesion components were computed to obtain the total minimum seismic passive resistance in soils by adding together the individual minimum components the effect of variation in wall batter angle ground slope wall friction angle soil friction angle and horizontal and vertical seismic accelerations on seismic passive earth pressures are considered in the analysis the seismic passive earth pressure coefficients are found to be highly sensitive to the seismic acceleration coefficients both in the horizontal and the vertical directions the results are presented in graphical and tabular formats

application of seismic refraction tomography in karst terrane seismic refraction tomography field data were collected on several bridge foundation sites in pennsylvania in close proximity to geotechnical boring locations profiles determined from these field measurements were plotted against drilling data and these comparisons revealed the ability of seismic wave velocities to differentiate overburden soil from rock in addition foundation construction data were collected at each of the sites and compared with refraction test results determined prior to construction in particular top of rock revealed by an excavation and pile tip elevations at driving refusal were compared with refraction test results from these data it appears that seismic wave tomograms can characterize the soil rock interface and that it is possible to predict expected design pile lengths based upon a measured p wave velocity tomogram it can be concluded from these site comparisons that geophysical techniques such as seismic refraction tomography can provide important additional information to site characterization for bridge foundations in karst terrane however these techniques should not be viewed as a replacement but should be conducted during design stage site investigation to aid selection of borehole locations and other testing needs

seismic and stratigraphic evidence for reef expansion and onset of aridity on the northwest shelf of australia during the pleistocene abstract modern reef the great barrier reef and ryukyu reef distribution in the indo pacific region is strongly controlled by warm currents east australian and kuroshio currents that radiate from the indo pacific warm pool the modern distribution of reefs south of 15 s on the western australian shelf is related to the presence of the warm leeuwin current however the age of the reefs south of 15 s and hence their temporal relationship to the leeuwin current has been largely unknown seismic and subsurface stratigraphic data show that reef growth and expansion on the northwest shelf of australia began in the middle pleistocene 0 5 ma the oldest ooids in the region are approximately synchronous with reef growth we suggest a two stage process for the spread of reefs to higher latitudes on the western australian coast first an increase in leeuwin current activity at approximately 1 ma brought warm waters and a tropical biota to the region and second increased aridity after 0 6 ma led to a decline in clastic input and increased alkalinity triggering ooid formation and reef expansion to higher latitudes associated with the switch to higher amplitude glacio eustatic cycles at the end of the middle pleistocene transition the timing and mechanisms for reef expansion south along the western australian coast has implications for the origin of the eastern australian middle pleistocene great barrier reef the new caledonia barrier reef and japanese ryukyu reef systems

estimation of active earth pressure against rigid retaining walls considering arching effects it is known that the distribution of active earth pressure against a translating rigid wall is not triangular but nonlinear owing to arching effects in the backfill in the present paper a new formulation is proposed for calculating the active earth pressure on a rigid retaining wall undergoing horizontal translation it takes into account the arching effects that occur in the backfill or retained soil mass in order to check the accuracy of the proposed formulation the predictions from the equation are compared with both existing full scale test results and values from existing equations the comparisons between calculated and measured values show that the proposed equations satisfactorily predict both the earth pressure distribution and the lateral active earth force on the translating wall in order to facilitate calculation of active earth pressures using the proposed equations a modified active pressure coefficient and an effective height of application of the lateral active force are also prov

active pressure on gravity walls supporting purely frictional soils the active earth pressure used in the design of gravity walls is calculated based on the internal friction angle of the retained soil or backfill however the friction angle of a soil changes during the deformation process for drained loading the mobilized friction angle varies between the peak and critical state friction angles depending on the level of shear strain in the retained soil consequently there is not a single value of friction angle for the retained soil mass and the active earth pressure coefficient changes as the wall moves away from the backfill and plastic shear strains in the backfill increase in this paper the finite element method is used to study the evolution of the active earth pressure behind a gravity retaining wall as well as the shear patterns developing in the backfill and foundation soil the analyses relied on use of a two surface plasticity constitutive model for sands which is based on critical state soil mechanics

seismic performance of underground reservoir structures insight from centrifuge modeling on the influence of structure stiffness abstractthe available simplified analytical methods for the seismic design of underground structures either assume yielding or rigid unyielding conditions underground reservoir structures do not fall into either of these categories in this paper we present the results of three centrifuge experiments that investigate the seismic response of stiff unyielding buried structures in medium dense dry sand and the influence of structure stiffness and earthquake motion properties on their performance the structure to far field spectral ratios were observed to amplify with increased structural flexibility and decreased soil confining pressure at the predominant frequency of the base motion lateral earth pressures and racking displacements for a range of structural stiffnesses were compared with procedures commonly used in design pre earthquake measured lateral earth pressures compared well with expected at rest pressures however none of the commonly used procedures adequately captured the structural loadin

development of a prototype for modelling soil pipe interaction and its application for predicting uplift resistance to buried pipe movements in sand this paper presents a testing rig for measuring the reactions on rigid pipes buried in sand during episodes of relative displacement following a detailed presentation of the 1g prototype the test

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

sediments and history of the rottnest shelf southwest australia a swell dominated non tropical carbonate margin abstract the rottnest shelf is a narrow wave dominated open shelf on the passive continental margin of southwest australia adjacent to a hinterland of low relief and sluggish drainage high physical energy low nutrients in cool subtropical waters and rapid postglacial transgression have limited carbonate productivity restricted grain types and reworked the transgressed surface to form only a thin given sufficient time the rottnest shelf could recover from drowning and form blanket like skeletal carbonates thin

pliocene pleistocene coastal events and history along the western margin of australia coastal deposits along the western coastal margin of australia a region of relative tectonic stability record plio pleistocene events and processes affecting the inner shelf and adjacent hinterland tectonic deformation of these deposits is more apparent in the carnarvon basin and rather less so in the perth basin the most complete record comes from the perth basin where units of pliocene and pleistocene ages are well represented in the perth basin the predominantly siliciclastic yoganup formation ascot formation and bassendean sand represent a complex of shoreline inner shelf and regressive dune facies equivalents the deposition of which began at an undetermined stage of the pliocene through to the early pleistocene the deposition of this sequence closed with a major regression and significant faunal extinction bioclastic carbonates characterize the middle and late pleistocene of the perth and carnarvon basins fossil assemblages include a distinct subtropical element unknown from the ascot formation and suggesting a strengthening of the leeuwin current the estuarine arcoid bivalve anadara trapezia characterizes assemblages of oxygen isotope stages 5 and 7 in the perth and carnarvon basins where it is now extinct deposits of substage 5e perth basin also record a southerly expansion of warm water corals and other fauna consistent with shelf temperatures warmer than present new uranium series ages on corals from marine sequences of the tantabiddi member of the bundera calcarenite of the western cape range are consistent with the double peak hypothesis for levels of substage 5e but the evidence remains less than conclusive initial uranium series dates from the bibra and dampier formations of shark bay indicate that both derive from the late pleistocene these numerical ages contradict previous interpretations of relative ages obtained from field studies the age relationship of the units requires further investigation

high precision mass spectrometric uranium series dating of cave deposits and implications for palaeoclimate studies calcite deposits in caves known as speleothem can provide valuable palaeoenvironmental information1 4 in particular because speleothem are deposited only in air filled caves gaps in deposition in coastal caves record high stands of sea level here we report the use of isotope dilution mass spectrometry to date speleothem by the uranium series method the use of mass spectrometry in uranium series dating was first applied to corals5 and has greatly improved the precision of this dating method the speleothem dated here a flowstone from 15 m below modern sea level in a bahamian cave records changes in sea level over the past 280 000 years the dated hiatuses in deposition indicate high sea level stands that are in general agreement with data from deep sea oxygen isotope stratigraphy6 and other estimates for the timing of high stands and glacial minima1 3 7

stratigraphy and timing of eolianite deposition on rottnest island western australia over 100 whole rock amino acid racemization aar ratios from outcrops around rottnest island 32 0 s latitude near perth indicate distinct pulses of eolian deposition during the late quaternary whole rock image alloisoleucine image isoleucine a i ratios from bioclastic carbonate deposits fall into three distinct modal classes or aminozones the oldest aminozone e averages 0 33 0 04 n 21 red palaeosol and thick calcrete generally cap the aminozone e deposits a younger aminozone c averages 0 22 0 03 n 63 comprising two submodes at 0 26 0 01 n 14 and 0 21 0 02 n 49 multiple dune sets of this interval are interrupted by relatively weak brown to tan protosols a dense dark brown rendzina palaeosol caps the aminozone c succession ratios from holocene dune and marine deposits aminozone a center on 0 11 0 02 n 15 comprising submodes of 0 13 0 01 9 and 0 09 0 01 6 calibration of a i averages from aminozones e and a are provided by u th and 14c radiometric ages of 125 000 yr marine oxygen isotope stage mis 5e and 2000 6000 14c yr b p mis 1 respectively the whole rock a i results support periodic deposition initiated during mis 5e continuing through mis 5c and then peaking at the end of mis 5a about 70 000 80 000 yr ago oceanographic evidence indicates the area was subjected to much colder conditions during mis 2 4 10 000 to 70 000 yr ago greatly slowing the epimerization rate eolianite deposition resumed in the mid holocene not vert similar6000 yr ago up to the present the a i epimerization pathway constructed from rottnest island shows remarkable similarity to that of bermuda in the north atlantic 32 n latitude these findings suggest that like bermuda the eolian activity on rottnest occurred primarily during or shortly after interglacial highstands when the shoreline was near the present datum rather than during glacial lowstands when the coastline was positioned 10 20 km to the west

research on time frequency analysis method of active earth pressure of rigid retaining wall subjected to earthquake aiming at the drawback existing in the analysis methods of seismic active earth pressure of rigid retaining wall the time frequency computational method is proposed based on the elastic wave theory and hilbert huang transform which is full 3d nonlinear time history analysis method it not only can consider the effect of three factors peak ground acceleration frequency and duration of the bidirectional seismic wave on the seismic active earth pressure but also can provide some valuable references for the time frequency seismic design of other types of retaining structures the reasonability of this method is verified by the shaking table test results and it is more accurate than some representative methods such as limit equilibrium method and coordinated deformation method at last some rules and conclusions can be obtained by the parameters study as shown in the following with the increase in pga the critical rupture angle decreases the resultant force of seismic active earth pressure increases and its application point of resultant force gradually moves up with the increase in frequency the critical rupture angle and the resultant force of seismic active earth pressure are distributed in the shape of saddle and the handstand saddle respectively and they achieve the maximum value when the frequency is close to natural frequency of rigid retaining wall but the application point essentially is unchanged

influence of underlying weak soil on passive earth pressure in cohesionless deposits finite element simulations demonstrate the influence of underlying weak soil on mobilization of passive pressures in cohesionless deposits traditional passive earth pressure theories with typical angles of interface friction may overestimate passive forces in such cases simple analytical models that incorporate the underlying weak soil using traditional passive earth pressure concepts are shown to agree reasonably with the finite element simulations the studies presented herein are relevant for cases in which cohesionless soil deposits overlie soft clay liquefiable sand or other weak layers

a 250 000 year climatic record from great basin vein calcite implications for milankovitch theory a continuous record of oxygen 18 18o variations in the continental hydrosphere during the middle to late pleistocene has been obtained from a uranium series dated calcitic vein in the southern great basin the vein was deposited from ground water that moved through devils hole an open fault zone at ash meadows nevada between 50 and 310 ka thousand years ago the configuration of the 18o versus time curve closely resembles the marine and antarctic ice core vostok 18o curves however the u th dates indicate that the last interglacial stage marine oxygen isotope stage 5 began before 147 3 ka at least 17 000 years earlier than indicated by the marine 18o record and 7 000 years earlier than indicated by the less well dated antarctic 18o record this discrepancy and other differences in the timing of key climatic events suggest that the indirectly dated marine 18o chronology may need revision and that orbital forcing may not be the principal cause of the pleistocene ice ages

monospecific pliocene oyster buildups murray basin south australia brackish water end member of the reef spectrum abstract paleoestuarine monospecific oyster bioherms and biostromes formed by the extant soft bottom oyster ostrea angasi are prolific in the pliocene norwest bend formation murray basin south australia these buildups are pioneer communities that record arrested ecological succession comprising only the stabilization and colonization stages of reef development each of these stages is directly linked to a different phase of marine inundation stabilization is restricted to the early transgressive systems tract when pre existing topographic highs were flooded and populated by dense aggregations of oyster clusters colonization is manifest throughout the transgressive and highstand systems tracts when increased accommodation allowed the vertical and lateral accretion of juvenile oyster communities into large buildups bioherms formed in areas of low terrigenous clastic sedimentation and seafloor disturbance both of which encouraged rapid community growth biostromes in contrast record buildup development on an unstable seafloor where episodic catastrophic community burial by storm sedimentation created repeated conditions of seafloor stabilization and colonization subaqueous dunes formed as part of the falling stage systems tract when river and tidal currents reworked shell material from bioherms and biostromes into large scale subaqueous bedforms brackish water conditions in the palaeoestuary a turbid water column mesotrophic nutrient levels and high spatial homogeneity of oyster buildups are interpreted to have prevented recruitment of specialized stenohaline organisms that typify the diversification stage of other metazoan reefs comparison with modern low diversity oyster communities imply that high fecundity and growth rates as well as exogenic nutrient cycling also made oysters in the norwest bend formation highly adapted competitors capable of thriving in this nutrient rich setting

seismic lateral pressures for design of rigid walls design charts for seismic pressures against rigid walls subjected to horizontal earthquake shaking are presented for both uniform and nonuniform backfills solutions are based on a simplified model of soil response which gives results that agree almost exactly with rigorous solutions peak seismic thrusts are presented for three different soil profiles for each profile 250 combinations of ground accelerations and distributions of soil shear moduli with depth are analysed to provide data points of peak seismic thrust ratios for the construction of design envelopes the seismic thrust ratios for design are presented as a function of the ratio of the predominant frequency of the earthquake motion and the fundamental frequency of the wall soil system an approximate method is given for evaluating the latter frequency without a full analysis

geomorphological evidence for late quaternary tectonic deformation of the cape region coastal west central australia abstract a late pleistocene marine isotope stage 5e emergent marine sequence fringes the coastline of the cape region of coastal west central australia and provides elevation and age control to characterize the locations and rates of crustal deformation there is a systematic measurable change in relative paleo sea level elevations across the cape region high precision leveling of modern and pleistocene shoreline features indicates the minimum elevation range of mis 5e shoreline features along the coast is 10 4 m this compares with the 2 5 m elevation range for observed modern shoreline analogs the lack of continuity of mis 5e shoreline elevations along 300 km of coastline demonstrates continuing tectonic deformation along coastal anticlines in the cape region topographic expression of mis 5e features indicates tectonic uplift consistent with late neogene to quaternary deformation on the cape cuvier and cape range anticlines post mis 5e tectonic uplift rates are up to 0 054 0 035 mm yr at fold axial locations estimated subsidence rates are 0 013 0 034 mm yr on fold limbs while the estimated vertical tectonic deformation is small and the rates are low the geomorphological data also demonstrate tectonic activity not stability

semi analytical approach to evaluate seismic passive earth pressures considering the effects of soil cohesion and a curvilinear failure surface abstractthe widely acknowledged mononobe okabe mo model is not recommended for seismic passive earth pressures analysis because it yields nonconservative results when the ratio of the wall s to t

seismic earth pressure on retaining structures a simple kinematic method to predict the seismic earth pressure against retaining structures is developed the fundamental solution to the free field seismic response considering nonlinear plastic behavior of soil is included in the retaining wall analysis for the first time perturbation to the free field response caused by soil structure interaction effects for different types of wall movement is considered results from this kinematic method are compared with those obtained from finite element analysis and observed from laboratory shaking table tests performed on model retaining walls

chronology of quaternary coastal aeolianite deposition and the drowned shorelines of southwestern western australia a reappraisal abstract aeolianite successions of low gradient continental margins commonly show complex records of coastal dune deposition linked to a wide range of sea level positions and climatic periods of the middle and late pleistocene recording both regional and broader scale drivers of sediment production coastal dune development and landform preservation to better characterise the general pattern of sedimentation that occurs over quaternary glacial interglacial cycles on low gradient temperate carbonate continental shelves we examine the morphology stratigraphy and age of aeolianite deposits in the perth region western australia this includes an analysis of well defined drowned coastal landforms preserved on the adjacent shelf new and previously published optical ages provide a preliminary timeframe for the deposition of aeolianite in the perth region and on rottnest island 17 km offshore an extensive aeolianite ridge near perth representing a former barrier has optically stimulated luminesence osl ages that range from 120 12 to 103 10 ka mis 5e 5a in the context of associated age uncertainties osl ages for an exposure in the same ridge 2 5 km inland record the onlap of much older aeolianite osl age 415 70 ka by shell rich estuarine beds osl age 290 30 ka a further 5 5 km inland from the coast two thick aeolianite units separated by a well developed palaeosol have stratigraphically consistent osl ages of 310 30 and 155 20 ka in contrast aeolianite units that form the northern coast of rottnest island have osl ages of 77 12 ka and 27 5 ka the new osl ages and previously reported tl and u th ages indicate that the bulk of the island comprises dunes deposited around the end of the last interglacial sensu lato mis 5a 4 and during the last glacial mis 4 2 accumulating over a last interglacial coral reef and basal calcarenite drowned barrier and dune landforms preserved on the adjacent continental shelf reveal that barriers were formed during periods of intermediate sea level e g mis 3 and significant dune mobility occurred when the shelf was subaerially exposed the pattern of shelf sedimentation discernible in the perth region large scale coastal carbonate dune deposition during periods of high and intermediate sea level and reactivation during glacial lowstands is largely consistent with published stratigraphic and age data for large scale aeolianite deposits on other low gradient carbonate shelves based on these data a general model is proposed for the cycle of quaternary sedimentation and landform evolution that occurs on these shelves which are dynamic sedimentary environments with coastal landforms and sedimentary successions that are very sensitive to erosion and sediment reworking

variability of holocene sealevel history along the southwestern coast of australia evidence for the effect of significant local tectonism abstract holocene sealevel records for the interval 7400 14c yrs b p to the present were determined from accretionary sequences at three separate localities within the perth basin of southwestern australia the three records all differ dramatically despite an overall separation of sites of only 170 km at the northernmost site the record shows sealevel was ca 1 0 m below present msl 7415 14c yrs b p and that it gradually rose to reach its present position ca 5100 14c yrs b p with no evidence for a raised sealevel nor for significant oscillations the record at the middle site shows a steadily declining sealevel from an initial high of ca 2 5 m at 6400 14c yrs b p and is consistent with eustatic hydroisostatic interpretations the southernmost site shows the most complex sealevel history of the three with a still stand at 2 or 3 m below present between 7000 and 5500 14c yrs b p an abrupt rise to 3 or 4 m above present msl between 4800 and 3800 14c yrs b p followed by a decline with sealevel reaching its present position ca 2800 14c yrs b p considered jointly the three differing sealevel records imply significant local tectonism during the holocene along the southwestern coast of australia the data further indicate that this coast can no longer be considered as tectonically stable as previously assumed and consequently the sealevel evidence can no longer be considered to reflect only eustatic and eustatic hydroisostatic influences

high resolution seismic refraction method using surface and borehole data for site characterization of rocks abstract the authors have developed a new method for the analysis of seismic refraction data which can handle both surface and borehole data simultaneously the main features of the method we developed are as follows 1 the algorithm of analysis is based on the tomographic reconstruction technique and refraction data can be analyzed almost automatically after traveltime picking 2 the method is applicable to both layered velocity structures and those showing a velocity gradient with depth 3 in order to apply the seismic refraction technique to a site that has a more complex structure the method can use the data obtained from sources and receivers on the surface as well as those within boreholes simultaneously numerical and actual field examples have shown that the method can greatly improve the accuracy and the reliability of the seismic velocity models obtained by the seismic refraction method as compared to the conventional analysis methods it can also shorten the data processing time drastically and reduce the survey cost

seismic passive earth pressure coefficients for sands by taking the failure surface as a combination of the arc of a logarithmic spiral and a straight line passive earth pressure coefficients in the presence of horizontal pseudostatic earthquake body forces have been computed for an inclined wall placed against cohesionless backfill material the presence of seismic forces induces a considerable reduction in the passive earth resistance the reduction increases with an increase in the magnitude of the earthquake acceleration the effect becomes more predominant for loose sands the obtained results compared well with those reported in the literature using curved failure surfaces however the results available in the literature on the basis of a planar failure surface are found to predict comparatively higher passive resistance

the distribution of 230th234u ages in corals and the number of last interglacial high sea stands abstract the 104 available 230 th 234 u analyses of unrecrystallized corals from stable emerged terraces indicate that the last interglacial period occurred approximately 125 000 yr ago an estimate is made of the exact duration of this period by accounting for the surprisingly small distribution width observed among the 80 most reliable analyses this distribution width is compared with those obtained for model populations generated by assuming various characteristic analytical errors and various lengths of the last interglacial period the results show that 1 if there was only a single rise in sea level it probably lasted no more than 12 000 yr in agreement with previous estimates and 2 if there were two separate rises of sea level the gap between them must have been less than 7500 yr and not 12 200 as proposed by some authors

the last interglacial ocean the final effort of the climap project was a study of the last interglaciation a time of minimum ice volume some 122 000 yr ago coincident with the substage 5e oxygen isotopic minimum based on detailed oxygen isotope analyses and biotic census counts in 52 cores across the world ocean last interglacial sea surface temperatures sst were compared with those today there are small sst departures in the mid latitude north atlantic warmer and the gulf of mexico cooler the eastern boundary currents of the south atlantic and pacific oceans are marked by large sst anomalies in individual cores but their interpretations are precluded by no analog problems and by discordancies among estimates from different biotic groups in general the last interglacial ocean was not significantly different from the modern ocean the relative sequencing of ice decay versus oceanic warming on the stage 6 5 oxygen isotopic transition and of ice growth versus oceanic cooling on the stage 5e 5d transition was also studied in most of the southern hemisphere the oceanic response marked by the biotic census counts preceded led the global ice volume response marked by the oxygen isotope signal by several thousand years the reverse pattern is evident in the north atlantic ocean and the gulf of mexico where the oceanic response lagged that of global ice volume by several thousand years as a result the very warm temperatures associated with the last interglaciation were regionally diachronous by several thousand years these regional lead lag relationships agree with those observed on other transitions and in long term phase relationships they cannot be explained simply as artifacts of bioturbational translations of the original signals

finite element analysis of lateral earth pressure on sheet pile walls abstract sheet pile walls providing lateral earth support are widely employed as excavation supporting systems for cutting slopes along the high speed railway in this study a validated three dimensional finite element fe model based on field measurements was used to explore lateral earth pressure distribution on sheet pile walls aiming to provide guidelines and recommendations for design of the sheet pile walls to this end the influence of pile length sheet s location pile s stiffness and soil properties on the pile performance were investigated the results showed that the optimum pile length was about 14 m for the sheet pile walls at a china high speed railway the sheet s location could affect the formation of soil arching and the mechanism of earth pressure distribution the moment of inertia of sheet pile walls was found to be effective in controlling pile displacement and earth pressure compared to young s modulus of the pile variations of soil parameters led to negligible changes in the earth pressure distribution furthermore a proposed simplified straight line form for earth pressure diagram based upon the fe analysis was developed compared with traditional earth pressure methods the proposed diagram considers the sheet effect overall the conducted study provided useful help toward the process of safer design and more economical sheet pile walls

three dimensional image of seismic refraction tomography and electrical resistivity tomography survey in the castle of occhiola sicily italy a geophysical survey was carried out at the ruins of occhiolacastle sicily italy a medieval village located at the north western part of a hill named terravecchia at 491 m asl in order to map the archaeological structures such as walls and burrows electrical resistivity to mography ert and seismic refraction tomography methods were used the resistivity variations are known to correlate quite well with the lithology thus providing important information for identifying the buried archaeological remains on the other hand seismic velocity variations provide information about the geometrical features of the remains the two geophysical methods are used in an enjoined way to better aid the interpretation and evaluate the significance and reliability of the results obtained with each single method the electrical and seismic data are displayed in three dimensions by using the iso resistivity and iso velocity surfaces respectively this allows us to effectively define the location of the anomalies present in the single electrical and seismic sections the results obtained in the survey highlight the presence of structures of regular shape probably due to features of archaeological interest 2006 elsevier ltd all rights reserved

u series and amino acid racemization geochronology of bermuda implications for eustatic sea level fluctuation over the past 250 000 years abstract bermuda is a stable mid oceanic carbonate platform for which a particularly complete record of late pleistocene eustatic sea level fluctuation has been reconstructed from a detailed study of geological field relationships combined with an extensive programme of u series and amino acid racemization geochronology only twice in the past 250 000 yr has sea level in bermuda been above its present level once at approximately 200 k y when it stood at about 2 m and most recently at 125 4 k y when it stood at 5 1 m these times of interglacial high sea level are characterized by the development of patch reefs and marine calcarenites at elevations above present sea level episodes of lower sea stand onto the bermuda platform at elevations higher than 20 m are observed within the two interglacial periods and are characterized by the deposition of eolianites by contrast glacial periods are times of residual soil formation and deposition of speleothems in caves at elevations below present sea level excellent correlation is observed between the bermuda glacio eustatic sea level record and other marine and terrestrial paleoclimate records

active earth pressure on retaining wall for c phi soil backfill under seismic loading condition this technical note describes the derivation of an analytical expression for the total active force on the retaining wall for c phi soil backfill considering both the horizontal and vertical seismic coefficients the results based on this expression are compared with those obtained from earlier analytical expressions for the active force for c phi soil backfill under seismic conditions and found to have a similar trend of variation the parametric study shows that the inclination of the critical failure plane with the horizontal plane decreases with the increase in values of seismic coefficients the decrease being more for their higher values the total active force increases with the increase in value of horizontal seismic coefficient while it decreases with the increase in value of vertical seismic coefficient except for a very high value of horizontal seismic coefficient design charts are presented for various combinations of horizontal and vertical seismic coefficients kh and kv and values of cohesion and angle of shearing resistance for estimating the total active force on the retaining wall for c phi soil backfill for practical applications

analysis of neotectonic structures in the eastern precordillera of argentina in relation to seismic hazard by the application of integrated geophysical methods abstract the city of san juan in the central western region of argentina has been the target of very destructive superficial earthquakes some of which have not been associated to a clear structural source up to this date the city is constantly growing outside the valley where it is located towards the area of eastern precordillera which is currently having an increased socio cultural activity thus this study is focused on increasing the geological knowledge of the latter by studying the eastern flank of sierra chica de zonda eastern precordillera whose proved neotectonic activity represents a geohazard on the basis of the general geological setting the neotectonic structures in the study area are related to a major active synclinal folding located just under the western sector of the san juan city geophysical potential methods gravimetric and magnetometric surveys were used to recognize contacts by contrast of density and magnetic susceptibility in order to reduce the ambiguity of these methods the gravi magnetometric results were constrained by using seismic and electrical tomographies these contacts where geophysical properties abruptly change were interpreted as faults despite many of them not having a superficial expression the latter being of great importance to asses the seismic hazard of the study area

refraction and amplitude attenuation tomography for bedrock characterization trabzon case turkey abstract the purpose of this study was to characterize the geomaterials and rock quality of eocene neogene aged volcanic sedimentary rocks in northeastern pontides trabzon turkey geomaterials characterization is a basic step for constructions structural design excavation and seismic microzonation studies volcanic sedimentary rocks have a wide distribution in the trabzon and are foundation rock for many buildings and roads they are also frequently used for surface work such as road pavement refraction tomography and amplitude attenuation tomography were applied to map p wave velocities vp and attenuation coefficients to determine rock quality and construction plans a 3 d vp and map was created from parallel lines of 2 d seismic data multichannel analysis of surface wave masw was also used to determine shear wave velocities vs four boreholes close to our seismic lines were used to determine the underground structure of the layers rock quality designation rqd and weathering degree laboratory tests were conducted on cylindrical specimens obtained from the boreholes to measure ultrasonic pulse velocities upv for saturated and dry conditions of basalts we also calculated the uniaxial compressive strength ucs water saturation water absorption in weight and effective porosity of samples the results indicated the studied area consists of three layers the surface layer was classified as topsoil with vp from 0 5 to 0 8 km s and thickness from 0 8 to 4 m the second layer was weathered basalt having vp from 1 6 to 2 3 km s and a thickness 2 6 m the bottom layer was identified as slightly weathered and massive basalt vp of this bedrock ranges from 2 4 to 3 8 km s with beginning at depth of about 4 m the average vs from masw was 0 95 km s 1 values were 8 and 23 for weathered and slightly weathered or massive basalt respectively regression analysis assessing the relation among upv ucs and porosity indicated a high correlation among them the seismic velocities 1 values boreholes logs and laboratory tests show that the bedrock is shallower and rock quality is better at the northern part of the study area therefore the northern part seems more suitable for constructions the combination of masw and seismic refraction plus traveltime and amplitude attenuation tomography revealed fractured and weathered zones more reliably and with greater detail than any one method could have done

a criticism of the proposed regional extent of late cenozioc arid zone advances into south western australia summary geomorphological sedimentological evidence for late cenozoicarid zone extensions is widespread in western australia however their regional extent into the extremes of southwestern australia is in dispute it has been suggested that a widespread coastal yellow sand facies is a desert eolian sediment indicative of arid zone advances into this region the claim is examined through a comparison of grain size characteristics grain surface textures and field relationships of coastal and inland sands

kinematics and geological constraints of the slow moving pisciotta rock slide southern italy abstract the pisciotta landslide is a slow moving deep seated rock slide in the campania region of southern italy which has damaged a provincial road several times in the last decades and currently poses a hazard to the national railway that intersects the toe of the landslide the landslide involves an oligocene turbidite series which is composed of intercalated calcarenites marls and mudrocks the principal objectives of this study were to investigate the morphological evolution of the unstable slope quantitatively analyse ground deformations and construct an engineering geological model that is consistent with the spatial features of the landslide the long term evolution of the unstable slope was assessed through the examination of available aerial photos from 1943 to 2006 kinematic analyses of the ground deformations were conducted based on observed progressive displacement of the road as evident from the topographic maps and orthophotos 1955 2006 and the bi weekly displacement survey of 50 targets distributed across the landslide area september 2006 march 2009 the engineering geological model of the landslide was reconstructed from the stratigraphic data obtained from the study of borehole data and monitoring of inclinometers as well as from geological structural and geophysical surveys the analysis of the aerial photographs revealed an early stage of deformation in 1943 which has been gradually widening since then in addition to the main scarp and the landslide flanks other significant landslide structures such as the longitudinal and transverse cracks as well as the positive or negative morphologies were monitored and mapped in the subsequent years these studies indicated a progressive erosion of the upper part of the slope and a bulging of the foot long term kinematic analysis based on the progressive displacements of the road allowed the measurement of the ground deformations from 1955 to 2009 which revealed a cumulative horizontal displacement of up to 53 m and an average velocity of 0 98 m year 1 which has increased in the recent decades in addition the recent monitoring of the ground deformations demonstrated a continuous activity with an approximately constant rate of displacement and a composite kinematic history of the landslide body through differential displacements and associated velocities the engineering geological model of the landslide was found to be controlled by specific stratigraphic and structural constraints the landslide involves a stratigraphic interval of the saraceno formation nord calabrese tectonic unit with a largely marly argillaceous composition whose structural setting displays complex folding at the mesoscale and faulting with an approximately monocline attitude of bedding and a downslope dip direction at the macroscale the left flank of the landslide rests on a normal fault

impact of cohesion on seismic design of geosynthetic reinforced earth structures abstractthis paper calculates the thrust of lateral earth pressures exerted by unstable slopes comprised of c soil and subjected to seismic pseudostatic loading conditions although the proposed method can be used for seismic stability analysis of geosynthetic reinforced earth structures gress the formulation and results are also applicable to many other relevant earth retention systems to study the impact of cohesion the authors develop formulations to determine the seismic active earth pressure coefficient for c soils resulting in a closed form solution the pseudostatic formulation considers the effect of tensile cracks backslope inclination and batter while assuming a log spiral failure surface two formulas are presented one is for the conventional inclination of thrust the second formulation considers a more feasible inclination of the thrust when it is likely to act against facing units with large setbacks constructed for large batter walls the authors perform parametric studies and

passive pressure coefficients critical failure surface and its kinematic admissibility using a combination of a logarithmic spiral and a straight line as a failure surface comprehensive charts have been developed to determine the passive earth pressure coefficients and the positions of the critical failure surface for positive as well as negative wall friction angles translational movement of the wall has been examined in detail considering the soil as either an associated flow dilatant material or a non dilatant material to determine the kinematic admissibility of the limit equilibrium solutions

conjugate stress approach for rankine seismic active earth pressure in cohesionless soils abstractthe rankine classic earth pressure solution has been expanded for the calculation of seismic earth pressure on rigid retaining walls supporting cohesionless backfill the expanded solution is based on the conjugate stress concept without employing any additional assumptions a single formulation is used for static and pseudostatic seismic analyses of active conditions the equation accounts for sloping backfill as well as wall inclination and can readily accommodate layered soil profiles and the presence of groundwater which require tedious analysis in commonly used methods a closed form expression as opposed to the constant value commonly used in practice has been derived for the soil wall friction angle as a function of the inertial forces and problem geometry for a given pseudostatic acceleration seismic lateral pressure increases with depth and the point of application of the resultant is calculated based on stratigraphy comparison of the formulation with the widely used mononobe oka

analytical solution for rankine s seismic active earth pressure in infinite slope abstractthis paper presents an analytical solution to determine seismic active earth pressure on a rigid frictionless retaining wall of c soil backfill with an infinite slope considering horizontal and vertical seismic coefficients this solution is a generalized explicit expression and was derived based on the rankine earth pressure theory and the mohr coulomb yield criterion to verify the derived solution a special case was analyzed and its result is identical to that obtained by earlier researchers by analyzing the distribution of the seismic active earth pressures along the wall depth a tension crack zone behind the wall was identified and the seismic active earth pressure coefficient considering the tension crack was obtained this study also investigated the effects of wall friction soil friction angle and dimensionless cohesion backfill slope and horizontal and vertical seismic coefficients on the seismic active earth pressure coefficients design charts for seismic active earth pressur

earth pressures against rigid retaining walls this paper outlines the results of unique shaking table experiments to determine neutral and active static and dynamic stresses and the points of application of corresponding total thrust generated by granular soils against rigid retaining walls and compares the experimental data with the well known coulomb and mononobe okabe equations a new criterion is proposed for identification of the wall deformation level at which the active state of stress develops this criterion states that active stress develops when the angle of friction between the wall and the backfill soil reaches its maximum value based on the above criterion experimental results show that the backfill soil enters the active state at much lower wall displacement levels than generally believed an equation is proposed for calculating the displacement necessary to initiate active static or dynamic stress this equation reveals that the displacement necessary to initiate active state increases with the height of the wall and decreases with backfill soil strength

seismic performance of underground reservoir structures insight from centrifuge modeling on the influence of backfill soil type and geometry abstractthe seismic response of underground reservoir structures is a complex soil structure interaction problem that depends on the properties of the earthquake motion surrounding soil and structure more experimental and field data of the response of these structures under different boundary conditions are needed to validate analytical and numerical tools this paper presents the results of four centrifuge experiments that investigate the seismic performance of reservoir structures restrained from rotational movement at their roof and floor buried in dry medium dense sand and compacted partially saturated silty sand this study focuses on the influence of backfill soil properties cover and slope on accelerations strains lateral distortions and lateral earth pressures experienced by the buried structure the structure to far field acceleration spectral ratios were observed to approach unity with added soil confinement density and stiffness both dynamic thrust and accelerations on the struc

seismic passive earth pressure coefficients using the method of characteristics the method of characteristics was used to generate passive earth pressure coefficients for an inclined wall retaining cohesionless backfill material in the presence of pseudostatic horizontal earthquake body forces the variation of the passive earth pressure coefficients k pq and k pgamma with changes in horizontal earthquake acceleration coefficient due to the components of soil unit weight and surcharge pressure respectively has been obtained a closed form solution for k pq is also provided the passive earth resistance has been found to decrease sharply with an increase in the magnitude of horizontal earthquake acceleration the computed passive earth pressure coefficients were found to be the lowest when compared to all of the previous solutions available in the literature

coulomb s solution to seismic passive earth pressure on retaining walls the conventional mononobe okabe method is widely used in practice but is only applicable for calculating total seismic earth pressure of cohesionless soil not for solving earth pressure distribut

significance of aeolian limestone lenses in quartz sand formations an interdigitation of coastal and continental facies perth basin southwestern australia abstract in the quaternary of the perth basin of southwestern australia the transition from coastal dune ridges to continental siliciclastic sand hinterland is a zone of calcareous sand or limestone lenses on or within siliciclastic sand in the holocene sequences the transition is a zone of landward extended and detached parabolic dunes which in section appear as lenses of calcareous sand resting on pleistocene quartz sand and limestone in the pleistocene sequences aeolian limestone lenses are common in thick sections of yellow quartz sand using the holocene coast to hinterland transition as an analogue the limestone lenses are interpreted to be buried outliers of attenuated parabolic calcareous dunes that migrated inland over an undulating plain of yellow quartz sand from a pleistocene coastal zone these dunes were later buried by influxes of aeolian yellow quartz sand during glacial age desert phases of the pleistocene in section these buried dunes form a zone of limestone lenses within aeolian quartz sand formations thus in a given time interval limestone lenses represent the transition between coastal and hinterland continental desert environments and record the extent that coastal dunes penetrated inland the pleistocene stratigraphic model of aeolian limestone lenses set within a sequence of aeolian siliciclastic sand is a distinctive style of coastal to continental transition which can be used to unravel similar sequences in the stratigraphic record where coastal aeolian calcareous facies interdigitate with desert aeolian siliciclastic facies

multiple geophysical methods examining neotectonic blind structures in the maradona valley central precordillera argentina abstract a high resolution superficial geophysical study was carried out in an area of the retroarc region of the andes mountains located in the southwest of san juan province 31 45 s 68 50 w central precordillera of argentina the main objectives of this study were to confirm the presence of blind neotectonic structures and characterize them by observing variations in magnetic susceptibility density and p wave velocities geological evidence demonstrates the existence of a neotectonic fault scarps affecting quaternary alluvial deposits in eastern piedmont of de las osamentas range in addition to direct observation of the cinematic of this feature in several natural exposures the maradona valley is characterized by the imbricated eastern vergence maradona fault system that uplifts neogene sedimentary rocks albarracin formation over quaternary late pleistocene holocene alluvial deposits the combined application of different geophysical methods has allowed the characterization of a blind fault geometry also identified on a natural exposure the magnetic data added to the gravimetric model and its integration with a seismic profile clearly shows the existence of an anomalous zone interpreted as uplifted blocks of miocene sedimentary rocks of formation albarracin displaced over quaternary deposits the application and development of different geophysical methods together with geological studies allow to significantly improving the knowledge of an area affected by quaternary tectonic activity finally this multidisciplinary study applied in active blind structures is very relevant for future seismic hazard analysis on areas located very close to populated centers

seismic passive earth pressures in soils seismic passive earth pressure coefficients were computed by the method of limit equilibrium using a pseudostatic approach for seismic forces composite curved rupture surfaces were considered in the analysis while earlier studies using this type of analysis were mainly for sands seismic passive earth pressure coefficients were obtained in the present study considering the effects of cohesion surcharge and own weight the minimum seismic passive force was obtained by adding the individual minimum values of these components and the validity of the principle of superposition was examined other parameters considered in the analysis were wall batter angle ground surface slope soil friction angle wall friction angle wall adhesion to soil cohesion ratio and horizontal and vertical seismic accelerations the seismic earth pressure coefficients were found to be highly sensitive to the seismic acceleration coefficients both in the horizontal and vertical directions results of the study are presented in the form of figures and tables comparisons of the proposed method with available theories in the seismic case are also presented

arching in granular soils limit state equilibrium one of the most critical assumptions in the application of arching theory is an accurate estimate of the coefficient of lateral stress k used to relate vertical and horizontal stresses on the ass