small scale modeling of onshore seismic experiment a tool to validate numerical modeling and seismic imaging methods the seismic imaging methods currently in the development stage need to be tested for experimental validation under controlled conditions yet natural media are very complex and moreover the parameters along the measurement profile prove difficult to evaluate independently of the seismic method itself to satisfy this need the ultrasonic measurement laboratory musc presented in this research has been devised to experimentally model seismic field measurements by using reduced scale models this facility is composed of small scale models of the underground an optical table with two moving arms a laser interferometer and adapted piezoelectric transducers used as the seismic sources the source system has been adapted to simulate the behavior of a point surface seismic source this is essential to reproduce the spatial energy distribution of a surface seismic source and supersedes the sources used in the past for other reduced scale seismic experimental models the comparisons of experimental data coll

p and s wave velocity models of shallow dry sand formations from surface wave multimodal inversion abstractsurficial formations composed of loose dry granular materials constitute a challenging target for seismic characterization they exhibit a peculiar seismic behavior characterized by a nonlinear seismic velocity gradient with depth that follows a power law relationship which is a function of the effective stress the p and s wave velocity profiles are then characterized by a power law trend and they can be defined by two power law exponents p s and two power law coefficients p s in case of depth independent poisson s ratio the p wave velocity profile can be defined using the vs power law parameters and poisson s ratio because body wave investigation techniques e g p wave tomography may perform ineffectively on such materials because of high attenuation we addressed the potential of surface wave method for a reliable seismic characterization of shallow formations of dry uncompacted granular materials we took into account the dependence of seismic wave velocity on effective pressure

seismic ground roll absorption and reemission by sand dunes this work was performed at schlumberger cambridge research where m i arran was a case student intern and e muyzert is a senior research scientist

high resolution shallow seismic experiments in sand part ii velocities in shallow unconsolidated sand we conducted a shallow high resolution seismic reflection and refraction experiment on a sandy beach the depth of investigation was about 2 m we interpret the data using the hertz mindlin contact theory combined with gassmann s equation these were used to obtain the vertical velocity profile then the profile was computed from seismic data using the turning rays approximation the normal moveout nmo velocity at the depth of 2 m matches the velocity profile as a result we developed a method to invert measured velocity from first arrivals i e velocity versus distance into velocity versus depth using only one adjustable parameter this parameter contains all the information about the internal structure and elasticity of the sand the lowest velocity observed was about 40 m s it is noteworthy that the theoretical lower bound for velocity in dry sand with air is as low as 13 m s we find that modeling sand as a quartz sphere pack does not quantitatively agree with the measured data however the the

the development of seismic reflection sandbox modeling analog sandbox models provide cheap concise data and allow the evolution of geological structures to be observed under controlled laboratory conditions seismic physical modeling is used to study the effects of seismic wave propagation in isotropic and anisotropic media and to improve methods of data acquisition processing and interpretation by combining these two independent modeling techniques the potential exists to expand the benefits of each method for seismic physical modeling the main advantages are that the seismic data collected from these models contain natural variations that cannot be built into conventional solid models which are machined with predetermined structures in addition the cost and construction time to build these models is significantly reduced for sandbox modeling the ability to record three dimensional 3 d seismic images before the model is manually sectioned for conventional two dimensional 2 d structural interpretation allows far more detailed study of subtle 3 d structures than previously possible in the past other workers have attempted to use unconsolidated sands for seismic physical models but these attempts have been unsuccessful because of the lack of control or understanding of the natural variations that occur throughout the models the aim of our research has been to overcome such problems and to develop techniques to alter the acoustic impedance of sand layers thereby allowing the subsequent ultrasonic seismic recording of 3 d fault systems in sand analog geological models

the properties of macerals in czechoslovak coals rich in inertinite abstract czechoslovak bituminous coals rich in inertinite contain a considerable amount of inertinite with a reflectance range displaced towards and partly overlapping that of the vitrinite reflectance together with the existence of the transitional maceral group of semivitrinite this causes difficulties in maceral analysis as well as in the technological evaluation of these coals the relationship between the volatile matter of vitrinite and its reflectance is very close for both vitrinite and inertinite rich coals the analogous relationship between the vitrinite reflectance and the volatile matter of inertinite displays a considerable scatter due to the effects of some higher values of the volatile matter of inertinite related to the presence of inertinite with relatively low reflectance the results of investigations into the coking properties of coals rich in inertinite however do not supply any proof of a higher fusibility of these coals

a preliminary morphology of precipitation systems in tropical northern australia a preliminary morphology of convective systems observed in the vicinity of darwin australia is presented several types of tropical convection during monsoonal and break season flow are identified using specific examples and compared with a range of systems observed worldwide in the general context of the bulk richardson number a significant spectrum of convective activity ranging from low shear and low convective available potential energy cape to high shear and moderate to high cape typical of mid latitude severe storms is identified significant differences between monsoonal flow and break season systems are apparent the formation of convective lines perpendicular to the low level shear and the apparent balance between advancing shallow cold pools and the shear are ubiquitous features convective scale downdraughts and mesoscale descent appear to be responsible for redistribution of 700 mb momentum to the planetary boundary layer pel the motion of the break season squall lines appears to result from an equilibrium between the cold pool and the undisturbed environmental pel flow deviations from this balance are hypothesized to result in the observed propagating and non propagating or slow moving modes examples of these modes are given showing the classical continuous development of new cells in a balanced state along the leading edge of long lived squalls and in the propagating case the discontinuous development of new cells on the cold pool ahead of the squall

retrieving 2d structures from surface wave data by means of space varying spatial windowing abstractsurface wave techniques are mainly used to retrieve 1d subsurface models however in 2d environments the 1d approach usually neglects the presence of lateral variations and because the surface wave path crosses different materials the resulting model is a simplified or misleading description of the site we tested a processing technique to retrieve 2d structures from surface wave data acquired with a limited number of receivers our technique was based on a two step process first we extracted several local dispersion curves along the survey line using a spatial windowing based on a set of gaussian windows with different shapes the window maxima span the survey line so that we were able to extract a dispersion curve from the seismic record for every window this provided a set of local dispersion curves each of them referring to a different subsurface portion this space varying spatial windowing provided a good compromise between wavenumber resolution and the lateral resolution of the obtain

a sedimentation device to produce uniform sand packs abstract in physical modelling using sand the construction of a sand pack is one of the main experimental difficulties existing solutions are generally based either on delicate manipulations pouring and scraping or on motorized sedimentation devices and the qualities of packs thus produced are known to affect experimental outcomes however uniformity planarity reproducibility and efficiency can be achieved with a simple sedimentation device without motors a rectangular reservoir pierced with holes rests on a support plate pierced with wider holes sand flows when the reservoir is displaced so that its holes match those of the support plate sand jets are diffused by planar horizontal sieves below which the sand sets into the experimental box tests on a 250 m median grain size sand show that the density is at its maximum value reproducible and uniform the spatial variations are only of 0 4 of the mean density thickness of the sand layers shows spatial variations around 2 of the mean thickness and 6 near the side walls very fine grains 90 m median grain size produce less uniform and less planar packs because of their greater sensitivity to air currents caused by the sedimentation according to direct shear tests the sand pack has a well defined static friction coefficient decreasing to a lower dynamic value after about 3 mm of slip with dilatancy in contrast poured sand packs which are initially less dense develop only the dynamic friction coefficient no peak shear stress during slip without dilatancy hole diameters hole spacing and the number and openings of the sieves are the parameters controlling the qualities of the sand pack for a given grain size distribution

geographical distribution of variance of intraseasonal variations in western indochina as revealed from radar reflectivity data abstract this study reveals remarkable differences in the geographical distribution of variance between two types of intraseasonal variations in daily mean radar reflectivity data in the western part of the indochina peninsula in this region the downa range lies parallel to the coast and separates the inland region from the coastal region the 30 60 day variation of reflectivity factor dominates most of the coastal region while its variance in the inland region is less than that of background red noise with the same frequency band horizontal gradients in the variance are largest over the range implying that the mountain range plays a significant role in the geographical contrast correlation analysis with reanalysis data shows that the variation only in the coastal region is associated with a synoptic scale zonal wind anomaly with the same time scale suggesting the importance of an orographic rainfall process that brings a large amount of precipitation only to the windward side of the downa range i

usefulness of petrographic classification in defining national coal resources abstract the usefulness of coal petrography for assessing and evaluating the properties of coal is well established such study is particularly helpful for evaluating indian coals which are conspicuously heterogenous in nature in a comparative study on the various schemes of classification and codification of coal using petrographic parameters the importance of an international petrographic classification has been stressed in the light of such a scheme originally suggested for categorising indian coals using vitrinite and exinite contents and reflectance of vitrinite as parameters an attempt has been made to define the various important coal deposits of the subcontinent they appear to be remarkably amenable to national planning from the standpoint of coal utilization

attenuation mechanisms in sands laboratory versus theoretical biot data the velocity and attenuation of compressional q 1p vp respectively and shear waves q 1s vs respectively determined with the pulse transmission technique at a frequency of about 100 khz are compared with the grain size shape porosity density and static frame compressibility of dry and water saturated sands except for vs all the quantities vp q 1p and q 1s are dependent on grain size and are higher in coarser grains than in finer grains q 1s decreases significantly with increasing differential pressure in coarse grained sediments but the same sediments show an anomalous increase with differential pressure in q 1p at low pressures we have also modeled the vp vs q 1p and q 1s of these samples to understand the mechanisms governing the observed changes the contact radius model with surface force effects predicts both vp and vs to be dependent on grain size frictional losses in unconsolidated coarse grained sands must also be considered at small strains 10 7 velocity and losses measured

physical modelling of a surface wave survey over a laterally varying granular medium with property contrasts and velocity gradients laboratory experiments using laser based ultrasonic techniques can be used to simulate seismic surveys on highly controlled small scale physical models of the subsurface most of the time such models consist in assemblies of homogeneous and consolidated materials to enable the physical modelling of unconsolidated heterogeneous and porous media the use of granular materials is suggested here we describe a simple technique to build a two layer physical model characterized by lateral variations strong property contrasts and velocity gradients we use this model to address the efficiency of an innovative surface wave processing technique developed to retrieve 2 d structures from a limited number of receivers a step by step inversion procedure of the extracted dispersion curves yields accurate results so that the 2 d structure of the physical model is satisfactorily reconstructed the velocity gradients within each layer are accurately retrieved as well confirming current theoretical and experimental studies regarding guided surface acoustic modes in unconsolidated granular media

small scale physical modeling of seismic wave propagation using unconsolidated granular media laboratory physical modeling and laser based experiments are frequently proposed to tackle theoretical and methodological issues related to seismic prospecting e g when experimental validations of processing or inversion techniques are required lasers are mainly used to simulate typical field acquisition setups on homogeneous and consolidated materials assembled into laboratory scale physical models pms of various earth structures we suggested the use of granular materials to study seismic wave propagation in unconsolidated and porous media and target near surface exploration and hydrogeologic applications we designed and tested the reproducibility of an experimental procedure to build and probe pms consisting of micrometric glass beads gbs a mechanical source and a laser doppler vibrometer were used to record small scale seismic lines at the surface of three gbs models when guided surface acoustic mode theory should prevail in such unconsolidated granular packed structure under gravity we only considered elastic wave propagation in stratified media to interpret recorded data thanks to basic seismic processing and inversion methods first arrivals and dispersion analyses we were able to correctly retrieve the gradients of pressure and shear wave velocities in our models a 3d elastic finite difference simulation of the experiment offered despite significant differences in terms of amplitudes a supplementary validation of our approximation as far as elastic properties of the medium were concerned

seismic velocities of unconsolidated sands part 2 influence of sorting and compaction induced porosity variation unaccounted for porosity variation in unconsolidated sediments can cloud the interpretation of the sediment s seismic velocities for factors such as fluid content and pressure however an understanding of the effects of porosity variation on the velocities can permit the remote characterization of porosity with seismic methods we present the results of a series of measurements designed to isolate the effects of sorting and compaction induced porosity variation on the seismic velocities and their pressure dependences in clean unconsolidated sands we prepared a set of texturally similar sand and glass bead samples with controlled grain size distributions to cover an initial porosity range from 0 26 to 0 44 we measured the compressional and shear wave velocities and porosity of dry samples over a series of hydrostatic pressure cycles from 0 1 to 20 mpa over this rangeof porosities the velocities of the dry samples at a given pressure vary by 15 however the water saturated compressional wave ve

seismic velocity and q model for the shallow structure of the arabian shield from short period rayleigh waves the shear velocity and q sub beta structure for the upper 1 km in different tectonic regions of the arabian shield have been investigated using high frequency vertical component records of rayleigh waves 1 20 hz which were recorded at source to receiver separations 55 80 km during a deep seismic refraction survey group and phase velocities of the fundamental and first higher modes were inverted for the shear wave velocity structure rayleigh wave attenuation coefficients were determined from the decay of the amplitude spectrum of the fundamental mode and used to invert for the q sub beta structure models derived from the data were tested by calculating synthetic seismograms for the fundamental and the first higher modes from surface wave theory with a center of compression used to represent the source both band pass filtered step and dirac delta source time functions were tested modeling indicates that the shear wave velocity of the shield increases from 2 6 km s to 3 4 km s in the upper 400 m of the crust q sub beta increases from 30 in the upper 50 m to 150 at 500 m depth the underlying material has a q sub beta of 400 500 for the outcropping igneous rocks such as granite and may reach values higher than 700 for the metamorphic green schist rock a band pass filtered dirac delta source time function produces the synthetic that is the best fit with observations

rock physics modeling of unconsolidated sands accounting for nonuniform contacts and heterogeneous stress fields in the effective media approximation with applications to hydrocarbon exploration by treating contact stiffness as a variable one can extend the effective medium approximation used to obtain elastic stiffness of a random pack of spherical grains more specifically we suggest calibrating effective media approximation based on contact mechanics by incorporating nonuniform contact models the simple extension of the theory provides a better fit for many laboratory and field experiments and can provide insight into the micromechanical bonds associated with unconsolidated sediments this approach is motivated by repeated observations of shear wave measurements in unconsolidated sands where observed shear wave velocities are lower than predicted by the hertz mindlin contact theory we present the calibration process for well log data from a north sea well penetrating a shallow gas discovery and a deepwater well in the gulf of mexico finally we demonstrate the benefit of using this model for amplitude variation with angle ava analysis of shallow sand targets in exploration and reservoir studies

elasticity profile of an unconsolidated granular medium inferred from guided waves toward acoustic monitoring of analogue models abstract the monitoring of materials elastic parameters during geological analogue experiments would highly improve the interpretation of involved processes it would more particularly help the implementation of joint analytical or numerical analyses we propose laser doppler vibrometry as a probing tool for the systematic characterisation of analogue models we therefore develop an experimental set up to record small scale seismic lines at the surface of an unconsolidated granular medium in laboratory conditions pressure wave first arrival times and surface wave dispersion are then inverted for a one dimensional pressure and shear wave velocity structure inferred profiles appear to match previously thoroughly estimated properties of the probed medium thus validating our approach

possibilities of the utilization of micropetrographic parameters in the scientific classification of bituminous coals abstract proposals for new scientific classifications of bituminous coals are based on micropetrographic parameters i e vitrinite reflectance as a criterion of the coalification and maceral composition presupposed to express the connection between the genetic peculiarities and physical chemical and technological properties of the coal mass in the case of coals with high inertinite contents however the utilizability of these parameters meets with difficulties resulting from the subjectivity of determining the different transitional material and from insufficient knowledge of inertinite behaviour at higher temperatures in the case of the maceral variable bituminous coals produced in the ostrava karvina coal basin these insufficiencies are not important since it is especially the expression of the variability of the properties of isometamorphic vitrinites which has decisive effects up on the course of the thermo chemical transformations that is of principal importance to the scientific classification of these coals in the first approximation the properties of isometamorphic vitrinites may be expressed by the parameter h o at closely connected with fluidity while the micropetrographic parameters reflect in particular the peculiarities in the chemical structure of the aromatic parts of coal macromolecules the parameter h o at expresses the properties of the non aromatic structures of vitrinite significantly affecting the course of its thermal degradation the experimental results show that the value of the parameter h o at fluidity and the course of degassing the coal of a lower coalification are independent of the maceral composition and vitrinite reflectance also that the caking and coking properties of low rank coals are especially dependent on the parameter h o at and partially on the micropetrographic parameters all these facts should be taken into consideration in preparing new scientific classifications of bituminous coals

tracking of velocity variations at depth in the presence of surface velocity fluctuations we tested a small scale experiment that is dedicated to the study of the wave separation algorithm and to the velocity variations monitoring problem itself it handles the case in which velocity variations at depth are hidden by near surface velocity fluctuations using an acquisition system that combines an array of sources and an array of receivers coupled with controlled velocity variations we tested the ability of beam forming techniques to track velocity variations separately for body waves and surface waves after wave separation through double beam forming the arrival time variations of the different waves were measured through the phase difference between the extracted wavelets finally a method was tested to estimate near surface velocity variations using surface waves or shallow reflection and compute a correction to isolate target velocity variations at depth

solving the mystery of booming sand dunes desert booming can be heard after a natural slumping event or during a sand avalanche generated by humans sliding down the slip face of a large dune the sound is remarkable because it is composed of one dominant audible frequency 70 to 105 hz plus several higher harmonics this study challenges earlier reports that the dunes frequency is a function of average grain size by demonstrating through extensive field measurements that the booming frequency results from a natural waveguide associated with the dune the booming frequency is fixed by the depth of the surficial layer of dry loose sand that is sandwiched between two regions of higher compressional body wave velocity this letter presents measurements of the booming frequencies compressional wave velocities depth of surficial layer along with an analytical prediction of the frequency based on constructive interference of propagating waves generated by avalanching along the dune surface

seismic velocities and poisson s ratio of shallow unconsolidated sands we determined p and s wave velocity depth profiles in shallow unconsolidated beach sand by analyzing three component surface seismic data p and s wave velocity profiles were calculated from traveltime measurements of vertical and tangential component seismograms respectively the results reveal two discrepancies between theory and data whereas both velocities were found to be proportional to the pressure raised to the power of 1 6 as predicted by the hertz mindlin contact theory the actual values of the velocities are less than half of those calculated from this theory we attribute this discrepancy to the angularity of the sand grains assuming that the average radii of curvature at the grain contacts are smaller than the average radii of the grains we modify the hertz mindlin theory accordingly we found that the ratio of the contact radius to the grain radius is about 0 086 the second disparity is between the observed poisson s ratio of 0 15 and the theoretical value 0 008 for random pack of quartz spheres this discrepancy can be reconciled by assuming slip at the grain contacts because slip decreases the shearing between grains poisson s ratio increases

seismic velocities of unconsolidated sands part 1 pressure trends from 0 1 to 20 mpa knowledge of the pressure dependences of seismic velocities in unconsolidated sands is necessary for the remote prediction of effective pressures and for the projection of velocities to unsampled locations within shallow sand layers we have measured the compressional and shear wave velocities and bulk shear and pwave moduli at pressures from 0 1 to 20 mpa in a series of unconsolidated granular samples including dry and water saturated natural sands and dry synthetic sand and glass bead samples the shear wave velocities in these samples demonstrate an average pressure dependence approximately proportional to the fourth root of the effective pressure vsp 1 4 as commonly observed at lower pressures for the compressional wave velocities the exponent in the pressure dependence of individual dry samples is consistently less than the exponent for the shear wave velocity of the same sample averaging 0 23 for the dry sands and 0 20 for the glass bead samples these pressure dependences are generally consistent over the entire pressure range measured a comparison of the empirical results to theoretical predictions based on hertz mindlin effective medium models demonstrates that the theoretical models vastly overpredict the shear moduli of the dry granular frame unless the contacts are assumed to have no tangential stiffness the models also predict a lower pressure exponent for the moduli and velocitiesvp1 6 than is generally observed in the data we attribute this discrepancy in part to the inability of the models to account for decreases in the amount of slip or grain rotation occurring at grain to grain contacts with increasing pressure

diurnal variation of precipitation by moving mesoscale systems radar observations in northern thailand 1 the diurnal cycle of radar echo data observed at om koi northern thailand during three rainy seasons may to october 1998 1999 and 2000 are analyzed from may to july when southwesterly monsoons blow over the observation area the diurnal cycles in the leeward regions inland of thailand show a phase delay that corresponds to the distance from the mountains in october when the wind direction reverses and blows from the east or northeast inland regions correspond to the upwind side of the mountains and do not show clear phase shifts the regions near the coast of the andaman sea which is the leeward in october show a similar phase shift of the diurnal cycle as the inland area during may july the echo tracking analysis reveals that echoes which are triggered near the mountains and moved to leeward regions caused phase delays which depended on the lee distance

scientific classification of bituminous coals abstract proposals for the new international classification systems of bituminous coals at present being prepared by the respective u n ece group of experts presuppose applying the micropetrographic parametes vitrinite reflectance as a measure of rank and inertinite content these parameters the utilizability of which is indisputable from the scientific point of view are not sufficient for a complete characterization of the coal mass properties in thermo chemical transformations particularly in the coking process these proposals therefore assume the use of further parameters specially the swelling index and volatile matter to eliminate the limitation of the micropetrographic parameters on the basis of an extensive sampling base of bituminous coals produced in the ostrava karvina coal district okr coals an evaluation was carried out of different parameters characterizing the most important properties of the coal mass and respective classifications were proposed selected classification parameters were vitrinite reflectance as a measure of rank associated with the properties of the ordered part of vitrinite macromolecules the h oat ratio reflecting the properties of their disordered part inertinite content and coking property expressed by the swelling index si the scientific character of this classification consists in the fact that it reflects significant physical and chemical properties which can be measured by means of the instrumental techniques available at present and moreover that it is associated with coal mass genesis in order to evaluate coal reserves in seams this classification has been modified to a less complicated variant using three parameters which is applicable to evaluating coal blends for coke production on the basis of expressing the coal blend composition according to rank

satellite and radar analysis of the volcanic cumulonimbi at mount pinatubo philippines 1991 1 several observers reported interesting convective phenomena in the months and years following the 15 june 1991 climactic eruption of mount pinatubo philippines the observed phenomena included deep convection resulting from 1 lower level eruptions 2 secondary phreatic explosions and 3 enhanced surface heating we have compared radar records and satellite imagery to obtain a more coherent understanding of these volcanic cumulonimbi from 17 june to 30 september 1991 and to identify observational challenges for future events geostationary satellite imagery analysis for the period shows that the dominant localized effect on convection following the eruption was to bring the afternoon evening peak in the diurnal convective cycle over the mountain forward by 2 3 hours we examined four cases in detail and identified a number of possible interactions between the volcano and the meteorological environment for three of these cases the volcanic emissions apparently mixed with cumulonimbi developing around the volcano on 21 june 1991 microphysical analyses clearly show a strong reduction in cloud top effective particle radius caused by the additional aerosols in the cloud while on the two other occasions there was a slight or barely detectible reduction in the fourth case for a cumulonimbus developing above a major secondary phreatic explosion no unusually small cloud top effective radii were found perhaps because the ash injected into the cloud was dominated by giant cloud condensation nuclei these cases verify that volcanic emissions can be released through the depth of the troposphere and lower stratosphere from relatively small eruptions future major tropical eruptions and their aftermaths should be studied using intensive ground and satellite based observations to explore these phenomena further

coal facies studies in australia despite the economic importance of coal to the australian economy detailed studies of controls on variation in coal type are remarkably few however important contributions have been made in the understanding of coal facies development tertiary lignite deposits of the gippsland basin provide key insights into the development of lithotype cyclicity and its relationship to relative sea level changes with individual paling up cycles being correlated to parasequences studies of permian hard coals have identified relationships between coal type and surrounding sediments unfortunately these relationships have been widely over interpreted in a manner that has diminished their real value

bias due to side wall friction in sand box experiments abstract the principal concern of this paper is with the accuracy and validity of experimental sand box models of geological structures and of thrust faults in particular as influenced by side wall friction side wall friction can produce undesirable artifacts in particular in experiments aimed at reproducing plane deformations the importance of such artifacts is revealed in the present study by the results of experiments that are affected in opposite ways by side wall friction two distinct experimental configurations have been chosen for this purpose for a set up that comprises a body of sand placed between vertical side walls on a basal plate against a back wall and a front wall all made of glass in configuration m the bottom plate and attached front wall move relative to the side walls towards a fixed back wall while in configuration f the back wall moves relative to the side walls and attached bottom plate towards a fixed front wall fixed fixed relative to the side walls in both configurations thrust traces on the top surface of the sand become curved near the side walls because of wall friction the outcome of altogether 31 experiments in the two configurations shows that the magnitude of the experimental bias depends on the ratio s l s b of the area of contact of the sand body with the side walls s l to its area of contact with the basal surface s b the bias is the difference in thrust locations in the two configurations it is measured on photographs taken through the side walls during the experiments away from the side walls the bias is estimated by the thrust curvatures observed in top views for s l s b 0 1 i e very little contact with side walls there is no identifiable bias furthermore a 2d theoretical solution reproduces well the results for s l s b increasing to 0 25 curvatures increase yielding rather different cross sections at the side walls but still similar cross sections in the central part of the sand body for s l s b 0 3 thrust planes occupy different regions of the box for each configuration although their curvature is decreasing at s l s b 0 9 curvatures have almost disappeared but the location of the thrusts and the length of the decollement depend strongly on the experimental configuration departures from the 2d theoretical solution are clearly stronger with configuration m than f another important conclusion is that the absence of curvature of the thrust traces is not a proof of the 2d character of the experiment mechanical equilibrium of the total forces recorded at both front and back walls during shortening shows that the thrust locations are controlled by the difference between basal and side wall shear forces

a study of consolidation using mechanical and electromagnetic waves consolidation has been a central topic of research in geotechnical engineering most studies have been conducted in oedometric cells and have attempted to assess the influence of multiple material