niobian rutile from the mcguire granitic pegmatite park county colorado solid solution exsolution and oxidation coarse crystals of niobian rutile occur in the hydrothermally altered core margin zone of the mcguire granitic pegmatite park county colorado associated with potassium feldspar quartz biotite ilmenite and monazite ce primary homogeneous niobian rutile with fe super 3 congruent to fe super 2 and a small excess of fe mn over the amount required to compensate the incorporation of nb ta w underwent three stages of exsolution primary homogeneous niobian rutile exsolved a fine trellis like pattern of minor lamellar nb bearing pseudorutile i most of this phase was broken down to pseudomorphs consisting of microgranular nb rich pseudorutile ii imbedded in niobian ferrian ferropseudobrookite continued exsolution in niobian rutile and reconstitution of the early exsolution products generated fe nb depleted microgranular niobian rutile titanian ferrocolumbite and minor ilmenite these three phases did not attain chemical equilibrium but may represent a stable phase assemblage all these processes seem to have maintained charge balance suggesting a closed system subsequent to the three stages of exsolution extensive oxidation converted the mineral assemblages to anatase hematite titanian tungstenian ixiolite primary ilmenite was oxidized into an anatase hematite intergrowth in both cases the hematite component was almost completely leached out leaving highly porous aggregates of the other phases the exsolution products in niobian rutile are controlled by the fe mn sc nb ta w ratio of the primary phase and by its fe super 3 sc fe super 2 mn ratio dominance of divalent a cations facilitates exsolution of titanian ferro to manganocolumbite or titanian ixiolite whereas dominant trivalent cations lead to exsolution of titanian fe sc super 3 nbo 4 phases excess fe mn over the columbite type fe super 2 nb 2 stoichiometry causes exsolution of fe mn rich nb ta oxide minerals or complementary fe mn ti phases

cone penetration test calibration for erksak beaufort sea sand interpretation of the cone penetration test in sands is generally based on empirical calibrations from tests in large diameter calibration chambers although interpretation of these calibration data for clean sands in terms of the state parameter is expected to be broadly applicable to other sands material specific correlations are desirable for many projects this paper describes a series of calibration chamber tests carried out on a sand dredged from the beaufort sea for construction of artificial islands this erksak sand is a uniformly graded subrounded medium grained sand with a fines content of 3 6 the testing chamber described is 1 4 m in diameter and allows independent control of vertical horizontal and back pressures on the sand sample samples of the sand were prepared by moist compaction to preserve the fines content and then back pressure saturated the chamber test data are presented and confirm that the erksak sand fits the general trends observed for other sands very well a method i

the downstream gradation of particle sizes in the squamish river british columbia the exponential downstream decline in particle size predicted by sternberg 1875 is examined within a highly active alpine fluvial environment the gravel bed squamish river in southwestern british columbia transect survey procedures for sampling within the coarse alluvial gravels are described in detail downstream trends for various particle size statistics plotted with distance from a major sediment source are considered according to two scenarios evaluation of overall trends indicates that the downstream expression derived by sternberg 1875 is not the most appropriate rather curves are better described by power functions this reflects a very rapid decline in particle size immediately downstream of the major sediment source secondly evaluation of downstream trends in relation to channel planform determines that exponential functions with different coefficients describe adequately relations within individual planform reaches there is insufficient evidence to suggest which of these two scenarios may be appropriate several lines of evidence suggest that the trends found are more the result of selective sediment transport phenomena than of abrasion a condition attributed to channel competence within a system dominated by sediment supply conditions

instruments for particle size and settling velocity observations in sediment transport in this paper we describe two sensors for measurement of particle size distribution and settling velocity distribution these measurements are critical to the correct estimation of the true sediment concentration in the field as well as to evaluating models for transport rates of sediments a multi angle measurement of laser scattering is made and inverted to obtain the particle size distribution since small angle scattering is relatively insensitive to particle composition the size distribution measurements are robust and do not require particle refractive index it is shown that with a knowledge of the size distribution true particulate volume concentration can be obtained unaffected in calibration by changes in particle size distribution the data from bottom boundary layer experiments using the instrument show the presence of temporal variability in size distribution associated with the strength of forcing of the boundary layer the importance of these observations lies in the implication that historical data acquired with single parameter optical or other sensors needs to be revisited in the second instrument analyzing the observation of size distributions during settling in a settling column produces settling velocity estimates in this case the history of concentration of each size class is examined to determine the settling velocity without invoking any assumptions of settling regime settling velocity data from a field experiment off the new jersey coast fit the model wf na 0 45 10 23 a 1 2 n

vertical profiles of suspended sand concentration and size from multifrequency acoustic backscatter vertical profiles of suspended sand concentration and size are obtained from multifrequency acoustic profiling data collected in 1989 during a nearshore experiment at stanhope lane beach prince edward island the data were acquired with acoustic sounders operating at 1 2 25 and 5 mhz independent estimates of concentration were made using optical backscatter sensors obss the algorithm for inversion of the three frequency backscatter data to particle size and concentration based on the ratios of the different signals was tested in laboratory experiments with an unconfined high reynolds number suspended sediment jet results from the stanhope beach experiment are presented for three different surface wave energy regimes with significant wave orbital velocities ranging from 0 3 to 0 8 m s and peak wave periods of 4 6 s the acoustic estimates of mean concentration are shown to be within 10 on average of those determined with the obs nearest the bottom at 5 to 10 cm height over time scales ranging from 6 5 min to 4 6 s one wave period the acoustic estimates of suspended sediment size near the bottom are within 5 20 of the bottom sediment mean size the statistical variability of the size estimates is high with standard deviations in the estimates ranging between 30 and 50 of the mean the time averaged concentration profiles exhibit an exponential decrease with height above an o 10 cm thick near bottom region of nonexpo nential decrease in contrast the time averaged mean size profiles decrease approximately linearly with height and rather slowly about 25 in 0 5 m

forewarning of static liquefaction landslides abstractstatic liquefaction failure and the ensuing flow slide of slopes have produced significant damages to structures and even loss of lives based on a very large number 1 632 of laboratory s

morphology and controls on the position of a gravel sand transition fraser river british columbia alluvial river channels often exhibit a relatively abrupt transition from gravel to sand bedded conditions the phenomenon is well documented but few prior studies have analyzed the spatial variability through reaches where transitions occur the downstream fining pattern observed in the fraser river is cited as a classic example of an abrupt gravel sand transition in a large alluvial channel however important questions regarding the exact location of the transition its sedimentology and morphology and what controls its location remain unanswered here we present observations of the downstream change in bed material grain size river bed topography and channel hydraulics through the reach within which the transition occurs these observations indicate that the gravel sand transition is characterized by a terminating gravel wedge but there are patches of gravel downstream of the wedge forming a diffuse extension we show that there is a dramatic decrease in shear stress at the downstream end of the wedge and a consequent cessation of general gravel mobility we argue that the patches of gravel observed beyond the wedge are the result of enhanced mobility of fine gravel over a sand bed we also find that sand in suspension declines rapidly at the downstream end of the wedge suggesting that sand is delivered to the bed completing the sedimentary conditions for a gravel sand transition we propose that the break in river slope associated with the transition is a consequential feature of the transition

yield strength ratio and liquefaction analysis of slopes and embankments a procedure is proposed to evaluate the triggering of liquefaction in ground subjected to a static shear stress i e sloping ground using the yield strength ratio su yield v0 thirty liquefaction flow failures were back analyzed to evaluate shear strengths and strength ratios mobilized at the triggering of liquefaction strength ratios mobilized during the static liquefaction flow failures ranged from approximately 0 24 to 0 30 and are correlated to corrected cone and standard penetration resistances these yield strength ratios and previously published liquefied strength ratios are used to develop a comprehensive liquefaction analysis for ground subjected to a static shear stress this analysis addresses 1 liquefaction susceptibility 2 liquefaction triggering and 3 post triggering flow failure stability in particular step 2 uses the yield strength ratio back calculated from flow failure case histories and the cyclic stress method to incorporate seismic loading

sediment transport along lower fraser river 1 measurements and hydraulic computations a comprehensive program of sediment transport measurements was conducted along lower fraser river british columbia between 1966 and 1986 the data yield a detailed sediment budget annual total suspended loads at three stations are virtually identical averaging 17 106 tonnes year t yr 1 the suspended sand load is about 5 5 106 t yr 1 about one third of the total in the gravel bed reach of the river the sand behaves as wash load significant transport of gravel begins at agassiz at a discharge of about 5000 m3 s 1 the annual gravel transport was estimated to be about 0 23 106 t yr 1 only 1 of the total load all of this material is deposited in the reach upstream of mission at mission sands finer than 0 177 mm make up more than 50 of the suspended sand load but are virtually absent from the sand bed therefore a portion of the sand load at mission is wash load the total bed material load here was estimated to be 3 0 106 t yr 1 about 18 of the total sediment load virtually all of the bed material load was transported in intermittent suspension near the bed less than 5 occurring as bed load in the long term the suspended sand load upstream is approximately equal to the total sand load at mission however within individual years some of the sand is stored within the reach temporarily and then reentrained later

specimen size effects on behavior of loose sand in triaxial compression tests triaxial tests are often used to determine the behavior and strength characteristics of soils without due attention to the differences in specimen size several drained and undrained monotonic triaxial compression shear tests are performed in this study on three different specimen sizes of the same sand to investigate the influence of specimen size and scale effect on sand compression and shear behavior the behavior of a sand specimen is strongly influenced by shear banding and specimen boundary conditions which are manifested as specimen size effects in the test results of this study the measured sand compressibility and shear strength parameters are employed to describe scale effects and investigate specimen size effects in liquefaction triggering analysis the results show that while larger specimens exhibit a less compressible behavior during isotropic compression larger shear strengths and effective friction angles are mobilized in the smaller specimens during shearing a number of geotechnical

hysteresis in suspended sediment to turbidity relations due to changing particle size distributions 1 turbidity t is the most ubiquitous of surrogate technologies used to estimate suspended sediment concentration ssc the effects of sediment size on turbidity are well documented however effects from changes in particle size distributions psd are rarely evaluated hysteresis in relations of ssc to turbidity ssc t for single stormflow events was observed and quantified for a dataset of 195 concurrent measurements of ssc turbidity discharge velocity and volumetric psd collected during five stormflows in 2009 2010 on yellow river at gees mill road in metropolitan atlanta georgia regressions of ssc normalized turbidity t ssc on concurrently measured psd percentiles show an inverse exponential influence of particle size on turbidity that is not constant across the size range of the psd the majority of the influence of psd on t ssc is from particles of fine silt and smaller sizes finer than 16 m this study shows that small changes in the often assumed stability of the psd are significant to ssc t relations changes of only 5 m in the fine silt and smaller size fractions of suspended sediment psd can produce hysteresis in the ssc t rating that can increase error and produce bias observed ssc t hysteresis may be an indicator of changes in sediment properties during stormflows and of potential changes in sediment sources trends in the psd time series indicate that sediment transport is capacity limited for sand sized sediment in the channel and supply limited for fine silt and smaller sediment from the hillslope

finite element analysis of the nerlerk underwater berm failures finite element analyses have been carried out to investigate the possible causes of failure during construction of the nerlerk underwater berm a hydraulically placed sand slope designed to form

stabilizing self organized structures in gravel bed stream channels field and experimental observations stable reticulate structures which we call stone cells have been observed in cobble gravel channel beds with low bed material transport rates experiments show that such structures develop simultaneously with the armor layer during an extended period when flows do not exceed the shields threshold by more than 2 times so that bed material transport is low they are constructed by particles moving from less stable positions into more stable configurations against each other intermediate developments include clusters and stone lines they reduce sediment transport by orders of magnitude and are evidently a major stability promoting mechanism in gravel channels the timescale for their development suggests that the boundaries of many gravel bed channels are not in equilibrium with recent competent flows but reflect the history of recent dominant flows

field evidence for rapid downstream fining of river gravels through selective transport doubts have been expressed about the ability of either abrasion or sorting to explain strong downstream fining of river gravels we describe pronounced fining over a short distance in a scottish river that has no human disturbance or lateral input of water and sediment measured abrasion rates are far too small to explain observed downstream fining but bed load trap measurements and the dispersion of magnetic tracer pebbles in six subreaches both show sorting during transport the observed downstream fining is also simulated well by a numerical sediment routing model using hydraulic and transport laws consistent with our field measurements the geomorphological cause of the strong fining is slope reduction above a local base level control in this common situation the development of downstream fining is part of the river9s tendency to minimize downstream variation in bed load transport rates and can proceed far more rapidly than the major aggradation otherwise required for equilibration

measuring suspended sediment concentrations using acoustic backscatter devices abstract in recent years the requirement to develop a technique for measuring suspended sediment concentration profiles with similar temporal and spatial resolution to that of electromagnetic current meter measurements of the flow has led to the development of an acoustic approach acoustic backscatter devices have been constructed and deployed in marine environments and measurements of backscattered signal profiles obtained however the translation from acoustic returns to suspended load has been an empirical procedure resulting in some uncertainty regarding the accuracy and reliability of the conversion process to address this problem a series of laboratory measurements of acoustic backscattering from marine suspensions were conducted using two acoustic backscatter instruments operating at 3 0 and 5 65 mhz a simple semi empirical backscattering theory has been developed to predict the form of the scattered signal and comparisons have been made of the concentrations predicted from the theory against concentration measurements made in laboratory tanks the results show that the main features of the backscattering signal can be explained and accurate concentration estimates can be made from the acoustic returns it is concluded that acoustic backscatter techniques are potentially powerful tools for examining at high resolution the structure of suspended sediment concentration profiles near the seabed

emergence of abrupt gravel to sand transitions along rivers through sorting processes gradual downstream fining along gravel bed rivers is often followed by a relatively abrupt change to a sand bed this has usually been explained by the breakdown of pebbles of certain lithologies to sand but it is not restricted to particular rock types and can occur over distances too short for significant abrasion an alternative explanation is that as shear stress declines downstream size sorting is enhanced through nonlinearities and thresholds in bedload transport and deposition mechanisms this hypothesis is tested by numerical modeling of an idealized channel with a mixed gravel and sand bed abrupt and persistent gravel fronts with associated breaks of slope develop from a range of smooth initial states when a new initial motion equation is used but not with a conventional equation the results suggest an emergent phenomenon but one that is sensitive to process specification rather than initial or boundary conditions

form and growth of bars in a wandering gravel bed river the changing form of developing alluvial river bars has rarely been studied in the field especially in the context of the fixed compound mainly alternate gravel bars that are the major morphological feature of the wandering style century scale patterns of three dimensional growth and development and the consequent scaling relations of such bars are examined along the gravel bed reach of lower fraser river british columbia canada a retrospective view based on maps and aerial photographs obtained through the twentieth century shows that individual bars have a life history of about 100 years except in certain protected positions a newly formed gravel bar quickly assumes its ultimate thickness and relatively quickly approaches its equilibrium length growth continues mainly by lateral accretion of unit bars consistent with the lateral style of instability of the river bar growth is therefore allometric mature bars approach equilibrium dimensions and volume that scale with the overall size of the channel accordingly the bars conform with several published criteria for the ultimate dimensions of alternate barforms sand bars observed farther downstream have notably different morphology fraser river presents a typical wandering channel planform exhibiting elements of both meandered and low order braided channels hydraulic criteria to which the fraser bars conform illustrate why this planform develops and persists the modest rate of bed material transfer along the channel typical of the wandering type determines a century length time scale for bar development this time scale is consistent with estimates that have been made for change of the macroform elements that determine the overall geometry of alluvial channels copyright 2009 john wiley sons ltd

influence of fines on the collapse of loose sands a study has been carried out to investigate the influence of fines and gradation on the skeletal collapse behaviour of loosely prepared sand samples loose sand samples formed by moist tamping and consolidated to the same effective stress level were prepared with varying percentages of both plastic and non plastic fines 74 m samples were isotropically consolidated and subjected to monotonic undrained triaxial compression results indicate that increased percentages of fines 0 5 this change is represented by a decreased strain softening behaviour and a shifting of the steady state line variation of the gradation of the host sand appears to have little effect on the monotonic undrained behaviour a supplemental study involving use of the scanning electron microscope was carried out to evaluate the findings of the test program in terms of sand fabric key words colla

1907 static liquefaction flow failure of the north dike of wachusett dam a static liquefaction flow failure occurred in the upstream slope of the north dike of wachusett dam near clinton massachusetts on april 11 1907 during the first reservoir filling the fine sands of the upstream dike shell liquefied and flowed approximately 100 m horizontally into the reservoir this paper presents a description of the construction of the north dike failure of the upstream slope and the results of stability analyses that were conducted to estimate the shear strength mobilized in the liquefied soils during failure analyses of the postfailure geometry the prefailure geometry and an analysis incorporating the kinetics of failure were conducted the back calculated shear strength considering the kinetics of failure is in agreement with other liquefaction flow failure case histories published in the literature as a result it is recommended that the kinetics of failure be considered to determine the shear strength mobilized during a liquefaction flow failure

effect of the mode of shear on static liquefaction analysis abstractthe current practices for determining the peak yield and postliquefaction critical undrained shear strength of liquefiable cohesionless soils for grounds subject to static shear stress e g sloping grounds or grounds beneath foundations require either a suite of costly laboratory shear tests on undisturbed field samples or empirical correlations with in situ penetration tests which do not account for the effect of the shearing mode on soil behavior improved correlations are developed in this study for estimating the undrained triggering and postliquefaction shear strengths of cohesionless soils which are based on the most reliable field liquefaction data from past cases of liquefaction flow failures and soil shearing behavior observed in a large database of 600 laboratory shear tests for different modes of shear the proposed method accounts for the variations in the mode of shear when providing estimates of the undrained triggering and postliquefaction strengths mobilized in static liqu

a correlation for permanent earthquake induced deformation of earth embankments abstract seismic design of earth dams and embankments is mainly controlled by the permanent deformation that may be induced directly or indirectly because of the design earthquake simple design charts such as those developed by yegian et al yegian m k marciano e a and ghahraman v g 1991 earthquake induced permanent deformations probabilistic approach j geotech eng 117 35 50 hynes griffin and franklin hynes griffin m e and franklin a g 1984 rationalizing the seismic coefficient method miscellaneous paper gl 84 13 us army corps of engineers waterways experiment station vicksburg mississippi makdisi and seed makdisi f i and seed h b 1978 simplified procedure for estimating dam and embankment earthquake induced deformations j geotech eng 104 849 867 and sarma sarma s k 1975 seismic stability of earth dams and embankments geotechnique 25 743 761 are often used to obtain a preliminary estimate of the permanent earthquake induced deformation of earth dams and embankments comparison of permanent deformations estimated from these procedures with observations from 122 published case histories on performance of earth dams and embankments during past earthquakes indicate that the estimated permanent earthquake induced deformations were in general smaller than the observed deformations however the observed permanent deformation davg was found to relate to the ratio of yield acceleration ay and the peak horizontal ground acceleration amax the scatter in the observational data upon which the davg ay amax relationship is based can be partly explained by the variations in the ratio of the fundamental elastic period of the earth structure td and the predominant period of the earthquake ground motion tp and the magnitude of the earthquake mw

analysis of earth dams affected by the 2001 bhuj earthquake an earthquake of magnitude of 7 6 mw 7 6 occurred in bhuj india on january 26 2001 this event inflicted damages of varying extents to a large number of small to moderate size multi zone earth dams in the vicinity of the epicenter some of the distress was due to the liquefaction of saturated alluvium in foundation liquefaction was relatively localized for the majority of these dams because the earthquake struck in the middle of a prolonged dry season when the reservoirs behind these dams were nearly empty and shallow alluvium soils underneath the downstream portions of the dams were partly dry otherwise liquefaction of foundation soils would have been more extensive and damage to these dams more significant six such dams have been examined in this paper four of these facilities chang shivlakha suvi and tapar were within the 50 km of epicenter region these dams underwent free field ground motion with peak ground accelerations between 0 28g to 0 52g of these chang dam underwent severe slumping whereas shivlakha suvi and tapar dams were affected severely especially over the upstream sections fatehgadh dam and kaswati dam were affected relatively less severely foundation conditions underneath these dams were first examined for assessing liquefaction potential a limited amount of subsurface information available from investigations undertaken prior to the earthquake indicates that although the foundation soils within the top 2 0 to 2 5 m underneath these dams were susceptible to liquefaction bhuj earthquake did not trigger liquefaction because of lack of saturation of these layers underneath the downstream portions of these dams these dams were then analyzed using a simple sliding block procedure using appropriate estimates of undrained soil strength parameters the results of this analysis for these structures were found to be in general agreement with the observed deformation patterns

downstream patterns of bed material grain size in a large lowland alluvial river subject to low sediment supply 1 a new data set of bimodal subaqueous channel bed sediments was analyzed for longitudinal patterns in grain size it yielded two interesting observations 1 separate fining trends in d50 exist for gravel and fines that overlap for 175 river kilometers and 2 this overlap in fining trends results in a protracted nonabrupt gravel to sand transition these suggest bed patchiness that is interpreted in the context of inherent grain size bimodality localized hydraulic sorting due to spatially heterogeneous and low sediment supply and local deviations in channel gradient the data also show that tributaries have a minor impact on main stem downstream fining due to basin shape and tectonic history in addition subaqueous channel sediments were observed to be finer than nearby sediments collected from exposed bars which may indicate a narrow active zone of transport where bars are disconnected from sediment movement this research has implications for bed material collection and theories of downstream fining

downstream changes in the lithology and grain size of fluvial gravels the watarase river japan evidence of the role of abrasion in downstream fining two processes have been considered to explain downstream grain size reduction in gravel bed rivers hydraulic sorting by which finer grains are transported faster and farther than coarse grains and abrasion by which individual particles are diminished in size most studies on the cause of downstream fining in rivers emphasize hydraulic sorting as the dominant fining mechanism however broken boulders are often observed in the bed material of japanese rivers also grain size changes may be correlated with the difference in resistance to breakdown among lithologies the purpose of this study is to use the lithologic composition of bed material on the watarase river to demonstrate that some downstream fining cannot be explained by hydraulic sorting alone the study reach on the watarase river flows on a dissected alluvial fan which means that the river is no longer aggrading the study reach is influenced only slightly by input of gravel from tributaries bed gravel in the study reach consists of several lithologies andesite quartz porphyry sandstone hornfels and chert the grain size distribution and lithology of the river bed material were examined at nine sites there are two principal results 1 size distribution of the gravel is strongly related to lithology andesite boulders or large cobbles make up the framework sizes in the upstream part of the study reach while chert pebbles make up the framework sizes in the downstream part there are few andesite pebbles or chert boulders in the river bed 2 longitudinal changes in the composition of each size class show selective transportation by lithology in every gravel size because the mobility of gravel depends mainly on its size hydraulic sorting by lithology does not occur within the same size class these results indicate clearly that particle abrasion occurs in the watarase river and is responsible at least in part for the downstream decrease in particle size of bed material

instrumented laboratory flowslides flowslides have been induced in small instrumented coking coal stockpiles by slowly raising the water table these strongly resembled field cases showing sudden collapse rapid fluid like motion and very flat final slopes failure initiated under essentially static drained conditions and with a mobilized secant effective strength parameter d much less than the steady state value highspeed measurements showed that excess pore pressures were generated during rather than before movement and liquefaction was therefore a result of shear failure rather than the cause des glissements par liquefaction furent provogues dans de petites reserves de charbon cokeflant a instrumentation par elevations lentes de la nappe aquifere ils ressemblaient beaucoup a des cas sur chantier avec affaissement abrupt un mouvement rapide quasi fluide et des pentes finales tres plates la rupture commenca dans des conditions drainees essentiellement statiques et avec un parametre o de resistance effective secante mobilisee

calculation of in situ acoustic sediment attenuation using off the shelf horizontal adcps in low concentration settings the use of off the shelf acoustic doppler velocity profilers adcps to estimate suspended sediment concentration and grain size in rivers requires robust methods to estimate sound attenuation by suspended sediment theoretical estimates of sediment attenuation require a priori knowledge of the concentration and grain size distribution gsd making the method impractical to apply in routine monitoring programs in situ methods use acoustic backscatter profile slope to estimate sediment attenuation and are a more attractive option however the performance of in situ sediment attenuation methods has not been extensively compared to theoretical methods we used three collocated horizontally mounted adcps in the fraser river at mission british columbia and 298 observations of concentration and gsd along the acoustic beams to calculate theoretical and in situ sediment attenuation conversion of acoustic intensity from counts to decibels is influenced by the instrument noise floor which affects the backscatter profile shape and therefore in situ attenuation we develop a method that converts counts to decibels to maximize profile length which is useful in rivers where cross channel acoustic profile penetration is a fraction of total channel width nevertheless the agreement between theoretical and in situ attenuation is poor at low concentrations because cross stream gradients in concentration sediment size or gsd can develop which affect the backscatter profiles we establish threshold concentrations below which in situ attenuation is unreliable in fraser river our results call for careful examination of cross stream changes in suspended sediment characteristics and acoustic profiles across a range of flows before in situ attenuation methods are applied in river monitoring programs

geochemistry of sauceboats excavated from independence national historical park philadelphia evidence for a bonnin and morris c 1770 73 provenance and implications for the development of nascent american porcelain wares abstract porcelain sauceboats excavated from a privy with a late 18th century 1786 or later context at independence national historical park inhp are anomalously al rich compared with previously analysed anglo american sulphurous phosphatic wares apart from their s content they are most similar to phosphatic w m reid porcelain brownlow hill liverpool c 1755 67 and its branch at shelton staffordshire in terms of their major element constituents but they contain heavy minerals e g tio 2 polymorphs and in this regard resemble a dated 1773 silicious aluminous calcic s a c bonnin and morris porcelain philadelphia openwork porcelain basket in terms of morphology and composition some tio 2 polymorphs in the 1773 basket match those from clay from white clay creek delaware a resource reputedly exploited by bonnin and morris their high nb cr ratios indicate derivation from a metapelitic or granitic pegmatite source so too do some from the inhp sauceboats although others are chrome rich 1 cr 2 o 3 indicating a mafic source the bedrock beneath white clay creek includes metasediments granitic pegmatite and metabasites e g of the wissahickon formation pointing to a local source for the tio 2 polymorphs in the porcelains described here although the evidence for a bonnin and morris provenance for the inhp sauceboats is circumstantial their enrichment in heavy minerals unusual perhaps experimental compositions and aesthetic characteristics nonetheless suggest a philadelphia origin for these artifacts the compositions of 18th century philadelphia porcelain support the contention that knowledge of phosphatic and s a c pastes originating in london was transferred first to staffordshire and liverpool and then to philadelphia perhaps via a potter by the name of w m ball

back analysis of the nerlerk berm liquefaction slides reply pressuremeter 39th canadian geotechnical conference ottawa hird c c and hassona f 1986 discussion on a state parameter for sands giotechnique 36 1 pp 123132 huntsman s r 1985 dctcrmination of ir sitlc lateral pressure of cohesionless soils by static cone penetrometer ph d thcsis university of california at berkeley berkeley ca huntsman s r m tcmell j k klejbuk l and sihinde s 1986 lateral stress measurement during cone penetration asce specialty conference on use of in situ testing in gcotcchnical engineering blacksburg va jefferies m g stewart h thomson r a a and roberts b j 1985 molikpaq deployment at tarsiut p 45 plenary session paper proceedings asce specialty confercncc on civil engineering in the arctic offshore arctic 85 san francisco mitchell d e 1984 liquefaction slides in hydraulically placed sands proceedings of 4th international symposium on landslides toronto m j o connor a n d associates 1982 an evaluation of the regional surficial geology of the southern bcaufort seas geological survey of canada report parry r h g 1971 stability analysis for low embankments on soft clays stress strain behaviour of soils roscoc memorial symposium cambridge g t foulis co henlcy on thames england sladen j a d hollander r d and k r a i n j 1985 the liquefaction of sands a collapse surface approach canadian geotechnical journal 22 4 pp 564 578

the liquefaction of sands a collapse surface approach recent large scale slides occurring during the hydraulic placement of an artificial island berm in the beaufort sea resulted from the liquefaction of the berm sand subsequent laboratory tests and

analysis of stability of earthen dams in kachchh region gujarat india the kachchh region of gujarat india bore the brunt of a disastrous earthquake of magnitude m w 7 6 that occurred on january 26 2001 the major cause of failure of various structures including earthen dams was noted to be the presence of liquefiable alluvium in the foundation soil results of back analysis of failures of chang tappar kaswati and rudramata earth dams using pseudo static limit equilibrium approach presented in this paper confirm that the presence of liquefiable layer contributed to lesser factors of safety leading to a base type of failure that was also observed in the field following the earthquake earth dams have been rehabilitated by the concerned authority and it is imperative that the reconstructed sections of earth dams be reanalyzed it is also increasingly realized that risk assessment of dams in view of the large scale investment made and probabilistic analysis is necessary in this study it is demonstrated that the probabilistic approach when used in conjunction with deterministic approach helps in providing a rational solution for quantification of safety of the dam and in the estimation of risk associated with the dam construction c 2007 elsevier b v all rights reserved

comparison of field observations of the vertical distribution of suspended sand and its prediction by models models for the vertical distribution of suspended sediment under waves and currents are compared with field observations the models include a diffusion based model a convection based model and a combined convection diffusion model the field observations were carried out at vilano beach florida in a water depth of approximately 3 to 4 m with a median grain diameter of 0 14 mm the rms wave height ranged from approximately 0 4 to 1 2 m under low waves the seabed was covered with very small ripples and under the higher waves sheet flow conditions were present the diffusion based model was found to best describe the observed data under high wave conditions but the convection model was more accurate under low wave conditions over all conditions the combined model was the most accurate these results are consistent with the different mechanisms for mixing suspended sediment over flat versus rippled beds

is the critical shields stress for incipient sediment motion dependent on channel bed slope data from laboratory flumes and natural streams show that the critical shields stress for initial sediment motion increases with channel slope which indicates that particles of the same size are more stable on steeper slopes this observation is contrary to standard models that predict reduced stability with increasing slope due to the added downstream gravitational force processes that might explain this discrepancy are explored using a simple force balance model including increased drag from channel walls and bed morphology variable friction angles grain emergence flow aeration and changes to the local flow velocity and turbulent fluctuations surprisingly increased drag due to changes in bed morphology does not appear to be the cause of the slope dependency because both the magnitude and trend of the critical shields stress are similar for flume experiments and natural streams and significant variations in bed morphology in flumes is unlikely instead grain emergence and changes in local flow velocity and turbulent fluctuations seem to be responsible for the slope dependency due to the coincident increase in the ratio of bed roughness scale to flow depth i e relative roughness a model for the local velocity within the grain roughness layer is proposed based on a 1 d eddy viscosity with wake mixing in addition the magnitude of near bed turbulent fluctuations is shown to depend on the depth averaged flow velocity and the relative roughness extension of the model to mixed grain sizes indicates that the coarser fraction becomes increasingly difficult to transport on steeper slopes

soil classification analysis based on piezocone penetration test data a case study from a quick clay landslide site in southwestern sweden abstract cone penetration test cpt and piezocone penetration test cptu methods can be effective in site characterization and are important for soil profiling and classification extensive experience exists that relates cpt and cptu results to soil type state and these are often the preferred in situ tools for subsurface investigations soil exploration and the evaluation of different engineering soil properties compared with conventional laboratory testing in this study eight methods consisting of traditional and nontraditional ones for soil classification and prediction of soil type and state using cptu data were examined and tested the cptu data not only provide valuable information on soil types but also can be used for deriving correlations with engineering soil properties for the purposes of hazard analyses and design of foundations we carried out and established a region specific correlation between cptu data and soil properties for three location test points in southwestern sweden at a quick clay landslide site first an analysis of the available cptu data was performed and then classification of the soils was made after determination and identification of the soil profiles the results were further evaluated using the unified soil classification system uscs and converted to cpt spt charts we summarize results from each of these methods including a description of the available charts and their performance for soil classification from cptu data we provide high resolution soil profiles from the three test points our work allowed the detection of potential sensitive fine grained clays which are responsible for landslides in the study area however in most cases occurring above coarse grained materials these materials were also detected in the cptu data and show good correspondence with available reflection seismic profiles from the site

static liquefaction of sand in plane strain experimental results on the static liquefaction behaviour of sand under plane strain conditions are presented in this paper undrained tests on very loose sand under both plane strain and axisymmetric conditions were conducted and the results compared the test data show that the undrained behaviour of sand under plane strain is similar to that under axisymmetric conditions however the critical state line csl on both the q p and the e p planes determined under plane strain conditions is different from that under axisymmetric conditions the slope of the csl is different as a result of the influence of the intermediate principal stress the state parameter which is measured with reference to the csl in the e log p plane is also different the value for plane strain is about 0 05 less than that for axisymmetric conditions for the sand tested the instability behaviour of very loose sand under undrained plane strain conditions is also studied based on the testing data a unique relationship

transient response in longitudinal grain size to reduced gravel supply in a large river 1 the first extensive dataset on subaqueous bed material grain size in a large river subject to reduced sediment supply is investigated alongside bathymetry modeled flow and sediment flux results suggest that following sediment supply decline and a shift to a finer sediment supply the gravel sand transition gst in fluvial systems extends and subsequently migrates upstream the non abrupt 125 km gst in the sacramento river corresponds with a hump in the long profile indicating recent downstream redistribution of sediment that impacts grain sizes the hump is composed of sediments winnowed from upstream gravel beds that accumulate downstream where slope declines this increases local sorting values and coarse sediment flux rates in the gst leading to further gravel loss by burial and net efflux thus in a transient response to sediment supply changes whether anthropogenic or natural the gst extends upstream as a longitudinally patchy bed modulated by bedload sheet transport that favors the loss of gravel

evolution of an advancing gravel front observations from vedder canal british columbia channelization of the lowermost part of vedder river in 1922 initiated a natural experiment relevant to the unresolved question of how abrupt gravel sand transitions develop along rivers the new channel vedder canal had a fine bed and a much lower slope than the gravel bed river immediately upstream changes in morphology and sedimentology as gravel advanced into and along the canal are documented using air photos historical surveys and fieldwork the channel aggraded and steepened until stabilized by occasional gravel extraction in recent decades the deposited material fines progressively along the canal but the gravel front has retained an abrupt appearance because it has advanced by the sequential development of discrete gravel tops on initially sandy alternate bars near the gravel front the bed is highly bimodal and there is a sharper drop in the extent of gravel framework surface facies than in bulk gravel content ahead of the front gravel is restricted to thin ribbons which often become buried by migrating sand calculations show that even though the gravel bed at the head of the canal is almost unimodal size selective transport during floods can account for the strong bimodality farther downstream copyright 2011 john wiley sons ltd

risk of sediment erosion and suspension in turbulent flows it is shown how some basic probability tools may help in the characterization of the turbulent processes involved in the mechanics of sediment transport both the initiation of sediment motion and the threshold for sediment suspension are analyzed in a stochastic frame of work isorisk curves are constructed based upon some minimum experimental information the well known shields curve is shown to correspond to an erosion risk of approximately 40 these concepts are believed to be of importance for the design of movable bed channels as well as for future experimental investigations which are indeed necessary for computing the risk for higher values of the particle reynolds number finally an approximate methodology is proposed for computing the risk of erosion

the development of small scale bedforms in tidal environments an empirical model for unsteady flow and its applications dimensions and plan morphology of current ripples are generally considered to vary with flow velocity and grain size recently however it has been shown that for sand of d50 0 095 and 0 238 mm the equilibrium dimensions are identical at all velocities within the stability field of ripples and that the plan form of equilibrium ripples is linguoid on this basis an empirical unsteady flow model has been developed and tested with flume experiments in order to predict ripple development in natural depositional environments the model includes the development of washed out ripples and upper stage plane bed the unsteady flow model explains the development and preservation of small scale bedforms in various tidal environments more accurately than previous models such bedforms can serve therefore as indicators of prevailing hydrodynamic conditions

too little too late the geochemistry of a 1773 philadelphia porcelain openwork basket abstract a dated 1773 openwork basket labelled philadelfia attributed to the bonnin and morris factory has a lead bearing silicious aluminous calcic s a c composition that contrasts with the phosphatic bone ash porcelains known to have previously been made during the mid 1760s to early 1770s in what is now the united states the basket was underfired and so contains relics of a flint pb glass flux but kiln temperatures were nonetheless sufficient for subsolidus pseudowollastonite and anorthite to have been resorbed implying that the duration of firing soaking near peak kiln temperatures was insufficient to ensure thorough vitrification during cooling liquidus pseudowollastonite and silica polymorphs but not anorthite formed showing that the melt was confined to the tridymite pseudowollastonite cotectic above the trd wol an eutectic 1170 c in the sio 2 al 2 o 3 cao system rapid cooling is also indicated by quenched silica polymorphs in the relict glass particles although bonnin and morris employed some former bow london c 1743 74 workers the s a c wares initially produced by this factory are compositionally distinct from the 1773 basket which in this regard more closely resembles the body and glaze of a reputed chelsea triangle period london c 1745 49 vessel regardless of how they obtained this technology it is ironic that bonnin and morris chose to abandon phosphatic pastes in favour of what in britain had become an obsolete formula

evaluation of flow liquefaction and liquefied strength using the cone penetration test flow liquefaction is a major design issue for large soil structures such as mine tailings impoundments and earth dams if a soil is strain softening in undrained shear and hence susceptible to flow liquefaction an estimate of the resulting liquefied shear strength is required for stability analyses many procedures have been published for estimating the residual or liquefied shear strength of cohesionless soils this paper presents cone penetration test based relationships to evaluate the susceptibility to strength loss and liquefied shear strength for a wide range of soils case history analyses by a number of investigators are reviewed and used with some additional case histories extrapolations beyond the case history data are guided by laboratory studies and theory

drained instability of sand in plane strain flowslide or failure of loose granular soil slopes is often explained using liquefaction or instability data obtained from undrained triaxial tests however under static loading conditions the assumption of an undrained condition is not realistic for sand particularly clean sand case studies have indicated that instability of granular soil can occur under essentially drained conditions e g the wachusett dam failure in 1907 laboratory studies on changi sand by chu et al in 2003 have shown that sand can become unstable under completely drained conditions however these studies were carried out under axisymmetric conditions and thus cannot be applied directly to the analysis of slope failures in this paper experimental data obtained from plane strain tests are presented to study the instability behaviour of loose and dense sand under plane strain conditions based on these test data the conditions for the occurrence of drained instability in plane strain are established using the modified sta

post liquefaction stability and deformation analysis of duncan dam duncan dam is a 39 m high zoned embankment and is founded on a deep deposit of unconsolidated sediments consisting of sands silts and gravels that are susceptible to liquefaction during earthquake loading a comprehensive program of field laboratory and analytical investigations was conducted to evaluate the liquefaction potential of the foundation soils and performance of the dam during an earthquake this paper describes the evaluation procedures and analyses and presents results of the post liquefaction stability and deformation analysis of the dam analyses were carried out based on the total stress approach using two methods namely the lab method and seed s method the lab method is a site specific direct laboratory based approach utilizing soil parameters from laboratory tests on undisturbed soil samples obtained in situ after freezing the ground seed s method is indirect and is based on field penetration data and past experience from earthquakes the lab method indicates that the residual

passive wedge formation and limiting lateral pressures on large foundations during lateral spreading abstractfour centrifuge tests supplemented by calibrated numerical simulations were performed to evaluate passive wedge formation and limiting lateral pressures imposed on a large stiff foundation

mobilization of coarse surface layers in gravel bedded rivers by finer gravel bed load 1 additions of sand to gravel beds greatly increase the mobility and flux of gravel however it is not known how additions of finer gravel to coarser gravel beds will affect the mobility of bed material here we examine the effect of fine gravel pulses on gravel bed material transport and near bed flow dynamics in a series of flume experiments bed material refers exclusively to sediment in the channel prior to the pulse introduction the observations indicate that fine sediment pulses tend to migrate downstream in low amplitude waves as the waves pass over the gravel bed the interstitial pockets in the bed material surface fill and coarse gravel particles are entrained this increases bed material transport rates and causes a distinct shift from a selective mobility transport regime where particles coarser than the bed material median 8 mm make up 30 of the load to an equal mobility transport regime where bed materials coarser than 8 mm and finer than 8 mm are transported in equal proportions the only possible source for this coarser bed load material is the sediment bed suggesting that portions of the coarse surface layer are being mobilized observations of near bed velocity and turbulence suggest that fine gravel pulses cause fluid acceleration in the near bed region associated with a reduction in the level of turbulence produced at the sediment boundary this accelerated fluid at the bed increases drag exerted on coarse surface layer particles promoting their mobilization our findings suggest that in general finer bed sediment not just sand can mobilize coarser sediment and that expressions for the influence of sand on bed mobility need to be generalized on the basis of grain ratios

liquefaction analysis of duncan dam using strength ratios b c hydro performed extensive seismic safety studies for duncan dam in the late 1980s and early 1990s the results of these studies indicated that duncan dam was reasonably safe from liquefaction induced failure a recently proposed liquefaction analysis procedure that uses strength ratios to assess liquefaction triggering and post triggering stability was used to revisit the liquefaction analysis of duncan dam when compared to the detailed field and analytical studies performed by b c hydro the proposed liquefaction analysis procedure predicts i similar zones of liquefaction within a contractive unit of foundation sand ii similar shear strengths at the triggering of liquefaction yield shear strength and at large strain liquefied shear strength and iii similar post triggering factors of safety for slope stability the good agreement suggests that the strength ratio based liquefaction analysis approach is relatively robust and is suitable for screening level studies for large projects or m

undrained behaviour of clayey sands in load controlled triaxial tests an experimental investigation of the untrained behaviour of a sand with small amounts of kaolin at moderate to large strains was carried out using a computer controlled triaxial cell the specimens were prepared by wet tamping using a sand obtained from southern mexico mixed with 3 5 and 7 kaolin by weight the testing programme concentrated on the study of normally consolidated samples subjected to different effective stress ratios during consolidation shearing was applied in compression and extension stiffness strength and the capability for generating pore pressures depend on the initial intergranular void ratio on the position of the stress state after consolidation relative to the failure envelope and on the loading path the intergranular void ratio and the normalized stress state at the onset of structural collapse and at the point of minimum strength are used to interpret the results using modifying factors that account for the effect of the consolidation stress ratio and the loading path

evaluation of liquefaction potential of foundation soils at duncan dam a comprehensive program of field laboratory and analytical investigations was carried out to evaluate the potential of liquefaction for the foundation soils at duncan dam duncan dam was completed in 1967 under the columbia river treaty in southeastern british columbia the 39 m high zoned embankment dam is founded on a sequence of sands silts and gravels some of the foundation soils may liquefy during earthquake loading and this would affect the stability and performance of the dam the liquefaction studies were carried out in two phases to characterize the engineering properties of the foundation soils and to assess its potential for triggering liquefaction using the total stress approach this paper describes methods of assessment of liquefaction potential using soil parameters based on field penetration data seed s method and laboratory testing of undisturbed soil samples obtained in situ after freezing the ground lab method and presents the results of triggering analysis influence of confin

influence of placement method on the in situ density of hydraulic sand fills the range of densities achievable by hydraulic placement of sand straddles the boundary between values giving acceptable potential performance and those giving unacceptable potential performance this has led to concerns over the safety of structures using hydraulic fills such as the artificial drilling islands in the canadian beaufort sea liquefaction failures of hydraulically placed sand have occurred at four or more of these islands until recently the factors affecting in situ density were little understood data obtained from several artificial islands are presented and these are used to demonstrate the overwhelming influence of method of placement on in situ density the possible reasons for this influence and the implications for design are discussed recommendations are made for research that together with conclusions drawn in the paper should allow hydraulic fills to be used with more confidence in the future key words sand hydraulic fill liquefaction cone penetration test

channel bed evolution and sediment transport under declining sand inputs 1 coupled field and laboratory investigations explore links between bed surface structure development and sediment transport as sand inputs decline on the pasig potrero river we investigated channel recovery following emplacement of sand rich pyroclastic deposits in the 1991 eruption of mount pinatubo philippines as sediment inputs declined from 1996 to 2003 surface grain size increased clast structures formed and sediment mobility and bed load transport rates declined our field results parallel those from flume experiments studying highly energetic channels with similar sand contents as the feed mixture shifted from 70 to 40 sand surface grain size and gravel interactions increased forming clusters and armor patches bed reorganization into patches initially accommodated coarsening with minimal effect on bed load transport rates roughness or friction angle within sandy transport zones as sand declined further gravel jams interrupted the connectivity of sandy transport zones lowering transport rates patch development lowered the threshold for the transition from sand dominated to gravel dominated transport focusing this transition over a narrow range of sand content

estimating suspended solids concentrations from backscatter intensity measured by acoustic doppler current profiler in san francisco bay california abstract the estimation of mass concentration of suspended solids is one of the properties needed to understand the characteristics of sediment transport in bays and estuaries however useful measurements or estimates of this property are often problematic when employing the usual methods of determination from collected water samples or optical sensors analysis of water samples tends to undersample the highly variable character of suspended solids and optical sensors often become useless from biological fouling in highly productive regions acoustic sensors such as acoustic doppler current profilers that are now routinely used to measure water velocity have been shown to hold promise as a means of quantitatively estimating suspended solids from acoustic backscatter intensity a parameter used in velocity measurement to further evaluate application of this technique using commercially available instruments profiles of suspended solids concentrations are estimated from acoustic backscatter intensity recorded by 1200 and 2400 khz broadband acoustic doppler current profilers located at two sites in san francisco bay california adcp backscatter intensity is calibrated using optical backscatterance data from an instrument located at a depth close to the adcp transducers in addition to losses from spherical spreading and water absorption calculations of acoustic transmission losses account for attenuation from suspended sediment and correction for nonspherical spreading in the near field of the acoustic transducer acoustic estimates of suspended solids consisting of cohesive and noncohesive sediments are found to agree within about 8 10 of the total range of concentration to those values estimated by a second optical backscatterance sensor located at a depth further from the adcp transducers the success of this approach using commercially available doppler profilers provides promise that this technique might be appropriate and useful under certain conditions in spite of some theoretical limitations of the method

use of adcps for suspended sediment transport monitoring an empirical approach a horizontally mounted 300 khz acoustic doppler current profiler was deployed in fraser river at mission british columbia to test its capability to detect size classified concentration of suspended sediment bottle samples in beam provide a direct calibration of the hadcp signals we also deployed a 600 khz vertically mounted adcp from a boat in combination with bottle samples fraser river at mission is 525 m wide with moderate suspended sediment concentration up to 350 mg l 1 in our measurements mostly silt and a modest sand load only at high flows we use an entirely empirical approach to calculate the sediment load using adcps to test the reliability of acoustic methods when assumptions embedded in the sonar equation about the relation between suspended sediment size and concentration and acoustic signals are violated vadcp calibration using matched individual bottle samples and acoustic backscatter departed from the expected theoretical relation calibration using depth averaged sediment concentration and acoustic backscatter more closely matched theoretical expectations but varied through the season hadcp calibrations conformed with theoretical expectations and did not exhibit seasonal variation silt and sand were successfully discriminated however silt dominates the correlations we found no coherent relation between acoustic attenuation and silt concentration in beam results are extended by correlation to estimate mean sediment concentration and total suspended flux in the entire channel this auxiliary correlation cancels any calibration bias and permits monitoring of size classified suspended sediment in absence of detailed information of sediment grain size distribution

geochemistry of wistarburgh glass ca 1739 1777 implications for batch recipes and distinction from other south jersey wares the wistarburgh factory was america s first successful glassworks since it operated largely prior to the american revolution little is known about its products and confusion surrounds the authenticity of some of the objects attributed to this factory however analysis of alkali lime glass sherds from the glassworks site shows that green wistarburgh bottle glass is much more calcic and is enriched in various trace elements notably the rare earth elements compared with later south jersey glass for which analytical data are available the compositional data indicate that wistarburgh s proprietors made use of a batch recipe containing approximately 68 wt local sand 24 dolomitic limestone and 3 each of soda ash and potash in addition to green bottle glass blue aquamarine and colourless potash lead glass and colourless potash glass were also recovered from the wistarburgh factory site suggesting that a range of specialized glasswares was produced by this factory resume l usine de wistarburgh a ete la premiere productrice de verre en amerique du nord les produits de cette usine qui fut surtout en production avant la revolution americaine ne sont cependant pas tres bien connus et des doutes persistent concernant la vraie provenance de plusieurs objets attribues au site de wistarburgh l analyses d eclats de verre de couleur verte trouves au site demontre cependant que ce verre est plus riche en calcium et en divers elements traces en terres rares particulierement que les autres types de verres de cette region les donnees de composition indiquent que le verre de wistarburgh a ete cree a partir d un melange de 68 de sable local 24 de calcaire dolomitique 3 d ecarbonate de sodium anhydre e t3 d e potasse en plus des eclats verts des morceaux de verre bleu et sans couleur riches en potasse et en plomb et de verre sans couleur riche en potasse ont ete retrouves au site de l usine de wistarburgh et suggerent que plusieurs types de verres specialises ont etes manufactures a cet endroit owen 697

effect of soil contraction tendency on static liquefaction triggering analysis static liquefaction failure occurs when the shear stress applied by a monotonic triggering load exceeds the undrained yield peak shear strength of the saturated liquefiable cohesionless soil in this study the effect of soil contraction tendency on static liquefaction failure of cohesionless soils is characterised by an empirical relationship between soil brittleness index and undrained yield strength from a database of 702 laboratory shear tests performed by the author and collected from past literature the application of this relationship for estimating the static liquefaction triggering strength of cohesionless soils is validated by comparison with several cases of liquefaction failures

liquefaction and flow failure during earthquakes two aspects of seismically induced liquefaction are discussed which are of vital engineering significance the triggering condition and the consequences of liquefaction the triggering condition is examined with respect to liquefaction analysis note being taken of the onset condition which is governed by cyclic strength consequences of liquefaction are discussed with respect to post seismic stability analysis in which the residual strength plays a major role procedures used for liquefaction analysis based on the results of in situ sounding tests are introduced and the applicability of this method for estimating associated ground settlements is discussed the evaluation of residual strength requires a better understanding of undrained sand behaviour results of extensive laboratory rests on japanese standard sand are examined and new index parameters are proposed to quantify undrained sand behaviour better the results of laboratory tests on silty sands are examined in the same way ah the results are