Showing papers in "Journal of Geotechnical Engineering in 1984"
TL;DR: In this paper, the authors discuss the application of applied probability in geotechnical engineering practice and present a number of applications where the probability can be used in the decision-making process.
Abstract: Recent years have seen rapidly growing research into applied probability and increased interest in applications to geotechnical engineering practice. Unfortunately, probability still remains a mystery to many engineers, partly because of a language barrier and partly from lack of examples showing how the methodology can be used in the decision‐making process. The following types of applications are described and illustrated in general terms: separating systematic and random errors when evaluating uncertainty in the stability of slopes; safety factors in connection with analysis of liquefaction; optimizing the design of an embankment in the face of uncertainty concerning stability; risk evaluation for an industrial facility built over potentially liquefiable soils; and risk evaluation for earth dams. Even when a precise quantification of probability of failure is not possible, systematic formulation of an analysis aids greatly in understanding the major sources of risk and thus points the way for costeffec...
321 citations
TL;DR: In this paper, the main current filter criterion, D15/d85⩽5, is shown to be conservative, but not excessively, and its use should be continued.
Abstract: Laboratory experiments have shown that uniform filters will catch particles with diameter of about 0.11D15 when the particles are carried in suspension in seeping water. Smaller particles will be carried through the filter pores and larger particles will not enter. The main current filter criterion, D15/d85⩽5, is shown to be conservative, but not excessively. Its use should be continued. Filter criteria using the ratios D50/d50 and D15/d15 are not supported by experiments or theory. Filters of angular particles of crushed rock are as satisfactory as those of rounded alluvial particles. It is not necessary for the filter particle size distribution to have a shape generally similar to that of the base particle size distribution.
310 citations
TL;DR: In this article, an inexpensive and realistic procedure is developed for estimating the lateral dynamic stiffness and damping of flexible piles embedded in arbitrarily layered soil deposits, where material and radiation damping due to waves emanating at different depths from the pile-soil interface are rationally taken into account; the overall equivalent damping at the top of the pile is then obtained as a function of frequency by means of a suitable energy relationship.
Abstract: An inexpensive and realistic procedure is developed for estimating the lateral dynamic stiffness and damping of flexible piles embedded in arbitrarily layered soil deposits. Starting point is the determination of the pile deflection profile for a static force at the top using any reasonable method—beam‐on‐Winkler foundation, finite elements, well‐instrumented pile load tests in the field, etc. Material as well as radiation damping due to waves emanating at different depths from the pile‐soil interface are rationally taken into account; the overall equivalent damping at the top of the pile is then obtained as a function of frequency by means of a suitable energy relationship. The method is applied to study the dynamic behavior of three different piles embedded in two idealized and one actual layered soil deposit; the results of the method, obtained by hand computations, compare favorably with the results of three dimensional dynamic finite element analyses.
310 citations
TL;DR: Sand deposits may undergo a significant loss in strength as a result of disturbance, thus behaving in some respects in a manner similar to sensitive clay as mentioned in this paper, and these phenomena appear to be related to solution and precipitation reactions involving quartz, amorphous silica, and other compounds and the formation of cementing bonds at interparticle contacts.
Abstract: Much evidence is now available that freshly deposited or densified saturated clean sand may exhibit substantial stiffening and strength increase with times up to several months. Sand deposits may undergo a significant loss in strength as a result of disturbance, thus behaving in some respects in a manner similar to sensitive clay. These phenomena appear to be related to solution and precipitation reactions involving quartz, amorphous silica, and other compounds and the formation of cementing bonds at interparticle contacts. The effects of these phenomena must be considered when evaluating the results of laboratory tests on reconstituted samples, in the assessment of ground improvement using deep densification, in the evaluation and interpretation of relative density measurements, and in the estimation of liquefaction potential.
229 citations
TL;DR: In this article, the authors presented data from four projects in which rates of leakage from ponds lined with clay significantly exceeded the rates that would have been predicted on the basis of laboratory permeability tests.
Abstract: Data are presented from four projects in which rates of leakage from ponds lined with clay significantly exceeded the rates that would have been predicted on the basis of laboratory permeability tests. The actual hydraulic conductivities of the clay liners were generally found to be 10 to 1,000 times larger than values obtained from laboratory tests on either undisturbed or recompacted samples of the clay liner. The source of difficulty with laboratory permeability tests is the problem of obtaining a representative sample of soil for testing. Neither recompacted samples nor small, undisturbed samples are likely to contain a representative distribution of desiccation cracks, fissures, slickensides, or other hydraulic defects that may be present in the liner. Field permeability tests were performed for three of the four case histories and yielded results that compared well with field performance. Field permeability tests seem to produce much better results than laboratory tests. The four projects had certai...
225 citations
TL;DR: In this article, the authors evaluate static stress condition, especially stress ratio effects on the low-amplitude dynamic shear modulus, G0, of three clean, dry sands.
Abstract: Resonant column tests involving anisotropic confining conditions were conducted to evaluate static stress condition, especially stress ratio effects on the low‐amplitude dynamic shear modulus, G0, of three clean, dry sands. Six static stress paths, involving both triaxial compression and triaxial extension, developed the desired ranges of stress ratios and stress histories. The results of these tests determined that increasing the stress ratio decreased G0, up to 20%–30%, but the reduction was not significant for stress ratios below about 2.0. Stress history caused a reduction in G0, but when the final stress ratio was the maximum value attained, the loading, unloading, and reloading path followed to develop this maximum value had little influence. The results also indicated that G0, depends about equally on the static principal stresses in the direction of wave propagation and in the direction of particle motion. The effect of the third principal stress appears to be unimportant. Two empirical equations ...
210 citations
TL;DR: In this article, field measurements from over 120 sites have been collected to study current practice and determine if similarities exist in the response of the ground to site improvement by dynamic compaction.
Abstract: Field measurements from over 120 sites have been collected to study current practice and determine if similarities exist in the response of the ground to site improvement by dynamic compaction. Data were obtained from published reports and files. Ground conditions at these sites were quite diverse, including natural sands, hydraulic fills, rubble, clay fills, and miscellaneous materials. General trends are presented which show that crater depths, ground vibrations, and the depth of influence increase with the energy per blow. The magnitude of induced subsidence, static cone resistance, standard penetration resistance, pressuremeter modulus, and limit pressure tend to increase with the applied energy per unit area.
189 citations
TL;DR: In this article, the effects of soil density and reinforcing strip length on the bearing capacity of reinforced and non-reinforcing sand were investigated, and the results showed that a significant increase in bearing capacity can be achieved at relative densities between 51 and 90% by the use of metal reinforcing strips.
Abstract: Laboratory bearing capacity model tests were performed on both reinforced and unreinforced sand loaded by a strip footing. The effects of soil density and reinforcing strip length were investigated. The tests show that a significant increase in bearing capacity can be achieved at relative densities between 51 and 90% by the use of metal reinforcing strips. Bearing capacity of reinforced sand is a strong function of the length of the reinforcing strips only until the strip length reaches approximately seven times the footing width; additional length does not significantly increase bearing capacity. For those tests on unreinforced sand where a distinct peak in the load-bearing pressure curve occurs (general shear failure), the failure of the corresponding reinforced sand occurs at a larger settlement. A comparison of test results with an analytical method of predicting bearing capacity of reinforced sand shows the importance of the soil-reinforcing strip friction coefficient.
187 citations
TL;DR: In this paper, a simple model is developed to predict the shapes and locations of failure surfaces in the soil, and conditions for development of a graben structure, as observed during normal movement on the bedrock fault, are also determined.
Abstract: Tests were performed on dense and loose sand in a glass‐walled fault test box to investigate the shapes and locations of failure surfaces that may occur in alluvium overlying active dip‐slip faults. The experimental procedure is reviewed and the results of the tests with reverse and with normal movements along the bedrock faults are presented. Based on the experimental results, a simple model is developed to predict the shapes and locations of failure surfaces in the soil. These are determined as a function of the depth of the soil, the angle of dilation for the soil, and the dip angle of the fault. The conditions for development of a graben structure, as observed during normal movement on the bedrock fault, are also determined. The emphasis of the study is on the mechanics of deformation and failure in cohesionless soil above dip‐slip faults in relation to principles of soil mechanics. The simple model is also evaluated in relation to real field conditions.
165 citations
TL;DR: In this paper, an investigation was made of the filters needed in dams for fine-grained clays and silts, and two different types of laboratory tests were developed to simulate the action of a critical filter (slot and slurry tests).
Abstract: An investigation was made of the filters needed in dams for fine‐grained clays and silts. The “critical” downstream filter in a central core dam should be capable of controlling and sealing a concentrated leak through the core, and should also be stable in conventional laboratory filter tests under a relatively high gradient, such as 1,000. Two different types of laboratory tests were developed to simulate the action of a critical filter (slot and slurry tests). Both gave identical and reproducible results. For fine‐grained clays a sand filter with D15 of 0.5 mm is conservative. For sandy clays and silts the filter criterion D15/d85⩽5 is conservative and reasonable. The Atterberg limits of a clay have no significant influence on the needed critical filter. For nondispersive and dispersive clays having similar particle size distribution the needed critical filters are the same. For “noncritical” filters, such as filters upstream of a clay core, quantitative filter criteria are not necessary.
161 citations
TL;DR: In this article, the influence of capillary stresses on values of the low-amplitude shear modulus, G\do, was found to be greatest for the soils having the smallest effective grain diameter, D\d1\d0, and for the lowest external confining pressure, σ\do'
Abstract: Resonant column tests of five fine-grained cohesionless soils showed the influence of capillary stresses on values of the low-amplitude shear modulus, G\do. This infuence was found to be greatest for the soils having the smallest effective grain diameter, D\d1\d0, and for the lowest external confining pressure, σ\do’. The maximum capillary influence developed at degrees of saturation between 5% and 20% for the soils tested. For the soil with the smallest D\d1\d0 (= 0.0024 mm) the maximum G\do was about two times G\do\d(\dd\dr\dy\d) for σ\do’ = 14.2 psi (98 kN/m). This latter pressure would correspond roughly to 20 ft. (6.1m) of overburden of incompletely saturated soils. Therefore, it would be expected that capillarity would affect insitu shear wave velocity measurements required for the dynamic design of shallow footings, runways, or other structures supported by soil near the ground surface. An empirical expression was developed which permits corrections of the value of G\do, measured at a particular degree of saturation, to the degree of saturation expected in prototype conditions.
TL;DR: In this paper, the authors developed a model for the evaluation of the critical state and subsequent displacement response of slopes to earthquakes, based on the calculated yield acceleration and the critical failure surface, which is then used to assess the soil displacements of slopes, which are subjected to a given earthquake load.
Abstract: TO avoid the complication in the calculation of progressive failure using the stress‐strain approach, and the inaccuracy of using the pseudo‐static analysis in seismic slope stability analysis, it is desirable to develop an effective method with which the critical state of the slope and the effects of earthquake on the slope stability can be determined directly. The present work is an attempt, within the framework of conventional pseudo‐static analysis, to develop a model for the evaluation of the critical state and the subsequent displacement response of slopes to earthquakes. The upper‐bound pseudo‐static limit analysis is applied for the determination of critical state of slopes, in this case, the yield acceleration and corresponding failure mechanism. Based on the calculated yield acceleration and the critical failure surface, Newmark's analytical procedure is then used to assess the soil displacements of slopes, which are subjected to a given earthquake load.
TL;DR: In this article, a qualitative analysis is performed to find which factors influence the membrane penetration and, at least approximately, to what extent, it is shown that apparent volumetric strain due merely to membrane penetration decreases linearly with increasing sample diameter.
Abstract: Membrane penetration effects in drained and undrained tests are discussed. A qualitative analysis is performed to find which factors influence the membrane penetration and, at least approximately, to what extent. It is shown that apparent volumetric strain due merely to membrane penetration decreases linearly with increasing sample diameter. The factor of major influence is the grain size but confining pressure, rigidity and thickness of membrane play a non-negligible role. A method to correct the measured values of pore pressure in undrained tests is proposed. It is shown that the correction factor depends on the volumetric stiffness of the sample which is not a constant but depends markedly on the state of stress.
TL;DR: In this article, an alternative method of calculating onedimensional primary consolidation of fine-grained material is presented, based on solution charts developed from a finite difference computer (FDC).
Abstract: An alternative method of calculating onedimensional primary consolidation of finegrained material is presented. The procedure is based on solution charts developed from a finite difference computer...
TL;DR: In this paper, a method for the analysis of load distribution of piles driven in sand and subjected to static vertical loads is presented for the purpose of determining residual stresses due to driving.
Abstract: A method is presented for the analysis of load distribution of piles driven in sand and subjected to static vertical loads. This method is unique in that it considers the existence of residual stresses due to driving. It uses the results of standard penetration tests to obtain the load transfer curves for friction and point resistance. These curves are modeled by hyperbolas which start at the residual friction and residual point pressure for zero displacement. The design method is based on a simple theory and a 33‐pile data base. Since each pile had sufficient instrumentation and a sufficiently complete load test program, the residual stresses and transfer curves could be determined with reasonable accuracy from the data base.
TL;DR: In this article, the shapes and locations of failure surfaces in alluvium overlying active diplip faults were studied on the basis of experiments performed in a fault test box, and a simple model for predicting primary failures was proposed.
Abstract: The shapes and locations of failure surfaces in alluvium overlying active dipslip faults are studied on the basis of experiments performed in a fault test box. A simple model for predicting primary...
TL;DR: In this paper, a simple thin layer element is developed and used in a finite element procedure for simulation of various modes of deformanon in dynamic soilstructure interaction, and the constitutive behavior of the i...
Abstract: A simple thinlayer element is developed and used in a finite element procedure for simulation of various modes of deformanon in dynamic soilstructure interaction. The constitutive behavior of the i...
TL;DR: In this article, a time-dependent plasticity model for rocks and soils based on Perzyna's elastic/viscoplastic theory is presented, wherein the plasticity yield function is patterned after the inviscid cap model developed over the last decade by Sandler et al.
Abstract: A time‐dependent plasticity model for rocks and soils based on Perzyna's elastic/viscoplastic theory is presented, wherein the plasticity yield function is patterned after the inviscid cap model developed over the last decade by Sandler et al. Three aspects are addressed: (1) Theoretical review and development; (2) numerical solution strategies suitable for a displacement‐based finite element method; and (3) illustrative examples of model behavior and comparisons with experimental data. The numerical solution algorithm employs a one‐parameter time integration scheme which provides options for explicit or implicit methods. Nonlinear equations resulting from the implicit method are solved by a Newton‐Raphson iterative technique, and efficiency versus accuracy studies are reviewed. Parameter identification and comparison of the model with experimental data is demonstrated for hard limestone in a variable loading history, soft sedimentary rock in triaxial creep tests, and well‐graded sand in slow and rapid lo...
TL;DR: In this paper, a methodology has been developed, and described in this paper, for predicting the fluctuation of groundwater levels as a function of precipitation, using measured characteristics of the site or region and a short period of calibration from a well record.
Abstract: High ground‐water levels are a principal cause of slope instability and of significance in other geotechnical engineering problems. A methodology has been developed, and is described in this paper, for predicting the fluctuation of ground‐water levels as a function of precipitation. The approximate method uses measured characteristics of the site or region and a short period of calibration from a well record. The linkage of precipitation to ground‐water fluctuation can be used in either deterministic or probabilistic methods. The new methodology has been tested by application in several different geological and climatological areas. Based on these field studies, the sensitivity of the methodology to calibration period, aquifer response time, evapotranspiration and other characteristics has been evaluated. The overall conclusion of the work has been a demonstration that the fluctuation of ground‐water levels, including extreme values, can be predicted with sufficient accuracy for many design and analysis p...
TL;DR: In this paper, the authors assess the accuracy of analytical methods now available to predict the foundation performance of offshore jack-up drilling rigs and present a case history of such analytical methods.
Abstract: An offshore fleet of about 435 mobile jack‐up rigs is currently drilling oil and gas wells around the world. About 2.6% of these jack‐up rigs annually experience an accident which is far greater than any other type of offshore drilling unit. Over one‐third of these accidents are associated with foundation problems. Certain geological conditions pose particular hazards to the foundation performance of mobile jack‐up rigs. To reduce the risk of foundation failure, these hazards can and should be identified by investigating subsurface conditions. Considerable interest is being given to assessing the accuracy of the analytical methods now available to predict the foundation performance of jack‐up drilling rigs. Some commonly used analytical methods are reviewed and actual case histories are presented.
TL;DR: In this article, the state of practice in laboratory measurements of hydraulic conductivity of soils was reviewed and found to be extremely variable, with the result that measurements on a given soil material often give variations of several orders of magnitude.
Abstract: Advective fluid flow, which depends directly on hydraulic conductivity, controls contaminant migration through soils in many cases. The state of practice in laboratory measurements of hydraulic conductivity of soils was reviewed and found to be extremely variable, with the result that measurements on a given soil material often give variations of several orders of magnitude. An experimental program was completed using compacted clay soils to study several facets of laboratory testing practice, and a suitable test procedure for consistent results was developed. Recommendations on several important aspects of procedure are presented. The procedure was also evaluated with a synthetic lead‐zinc tailings leachate, and alteration of the test soils' hydraulic conductivity was evaluated and correlated with probable chemical interactions of the test permeants and soils.
TL;DR: In this article, the ability of simple load control tests to predict strains developed in complex (storm profile) tests is found inadequate, and it is suggested that only the minimum cyclic stress ratio associated with the fully weakened state has any direct design relevance.
Abstract: Data are presented from cyclic triaxial tests on remoulded clays with load or displacement control. The ability of simple load control tests to predict strains developed in complex (storm profile) tests is found inadequate. It is suggested that only the minimum cyclic stress ratio associated with the fully weakened state has any direct design relevance. The minimum cyclic stress ratio varies with frequency. If data from load controlled tests are re‐analyzed to account for rate effects on shear strength then a constant value independent of frequency is observed. However, measurement is approximate and requires several extended tests. It is found that the fully weakened state for the soil tested can be achieved in a single displacement controlled test provided that 10,000 cycles at a mean double amplitude strain of at least 5% are applied. Irrespective of data re‐analysis, the minimum cyclic stress ratio measured in a single displacement controlled test is constant for frequencies less than 1/5 Hz. Within t...
TL;DR: In this paper, a history of parallel development of earth core and concrete-face rockfill dams and the impact of compacted rockfill on the concrete face rockfill dam is discussed.
Abstract: Karl Terzaghi, a major contributor to progress in embankment dams, made significant contributions to the understanding of properties of rockfill and to the improvement of design of the concrete-face rockfill dam His contributions are noted and followed by a history of parallel development of earth core and concrete-face rockfill dams and the impact of compacted rockfill on the concrete face rockfill dam Emphasis in this paper is directed towards the concrete face type of rockfill dam, since the earth core type is already well-covered in the literature Recent progress in the design and construction of the concrete-face rockfill dam is outlined and documented Design trends and performance data are presented
TL;DR: In this article, a study of post-construction crest settlements and deflections of 68 rockfill dams has been made in order to assess the usefulness and accuracy of the prediction of such deformations using empirical equations.
Abstract: A study of the post-construction crest settlements and deflections of 68 rockfill dams has been made in order to assess the usefulness and accuracy of the prediction of such deformations using empirical equations. Graphs of deformation per unit height against time are plotted for membrane-faced (dumped and compacted rockfill), sloping, and central core dams. Comparisons of predicted and observed movements show that use of empirical equations can lead to large errors. An alternative approach is proposed, using only the deformation curves of existing dams with similar characteristics to the dam under consideration. Details are given in tabular form for each of the dams in the survey, as an aid to this approach.
TL;DR: In this article, the stability of spread footing situated above a continuous void was investigated using a theoretical analysis and a model footing testing, and the results indicated that there is a critical region under the footing, and only when the void is located within this region will the footing performance be significantly affected by the presence of the void.
Abstract: The stability of spread footing situated above a continuous void was investigated. The study involved a theoretical analysis and a model footing testing. The theoretical analysis was made using the finite element method in which the foundation soil was idealized as an elastic perfectly plastic material. The model footing testing was performed on a commercially available kaolinite, which was compacted to 95% compaction based on the standard Proctor comparitive effort. The model footing test results were compared with those obtained from the finite element analysis. As a result of this study, a three-dimensional finite element computer program was developed. Using this computer program, the stability of spread footing was analyzed for different conditions. The results of the analysis indicate that there is a critical region under the footing. Only when the void is located within this region will the footing performance be significantly affected by the presence of the void. The size of the critical region depends on several factors such as footing shape, soil property, void size and void shape. When the void is located within the critical region, the bearing capacity of the footing varies considerably with the void location.
TL;DR: In this article, the authors report on the magnitudes and distribution of static atrest stresses behind a rigid wall as a function of soil densification and on static active stresses mobilized behind the wall.
Abstract: This paper reports on the magnitudes and distribution of static atrest stresses behind a rigid wall as a function of soil densification and on static active stresses mobilized behind a rigid wall r...
TL;DR: In this article, a new procedure is proposed that utilizes equipment available in almost any geotechnical laboratory to simulate the saturation of sand specimens in laboratory investigations, where an initial vacuum is applied to the sand specimen in such a manner as not to elevate effective stresses.
Abstract: Saturation of sand specimens in laboratory investigations is necessary to provide reliable measurements of volume change and pore pressure. Conventional methods utilize back pressuring or back pressuring with supplemental use of carbon dioxide. If no carbon dioxide is used, back pressures can easily become undesirably large. On the other hand, the percolation of carbon dioxide through the sand to reduce back pressures can lead to unwanted reaction with soil components. To overcome these problems, a new procedure is proposed that utilizes equipment available in almost any geotechnical laboratory. A theoretical and experimental basis is provided as justification. In the new method, an initial vacuum is applied to the sand specimen in such a manner as not to elevate effective stresses. The soil may be dry, saturated, or partially saturated. After the vacuum is held for no more than five minutes, normal back pressuring techniques are used. It is found that sands can be effectively saturated at very low values of back pressure. The procedure is especially useful in normally troublesome materials such as cemented sands.
TL;DR: In this paper, a numerical model for calculating permanent strains and stresses in sand caused by cyclic loading is presented, which is fitted to the results of drained static and cyclic triaxial tests.
Abstract: This paper presents a numerical model for calculating permanent strains and stresses in sand caused by cyclic loading. The model is fitted to the results of drained static and cyclic triaxial tests. The model can predict permanent stresses and strains resulting from drained or undrained cyclic loading under various boundary conditions. Predictions of the model are compared with experimental results from cyclic oedometer tests and cyclic undrained triaxial tests. Good correlation exists between the predicted and measured response.
TL;DR: In this paper, the critical moisture content is defined as the moisture content at the knee of the thermal resistivity-versus-moisture-content curve in a soil.
Abstract: Information on the thermal properties of soils from different disciplines of science and engineering is consolidated to identify low-cost, simple procedures for assessing the variation of the thermal resistivity of soils with changes in moisture content. Three procedures for determining the critical moisture content are presented. The critical moisture content is the moisture content at the knee of the thermal-resistivity-versus-moisture-content curve. The optimum moisture content and plastic limit were found to be physical quantities indicative of the critical moisture content in soils. Also, the upper flex point of the soil-moisture-characteristics curve appears to establish the critical moisture content in soils.
TL;DR: In this paper, the AASHTO standard reference material, a silty clay, was used to test the soil thermal behavior and the limit states of fine-grained soils.
Abstract: Laboratory thermal probe tests performed on an AASHTO standard reference material a silty clay showed that the soil thermal behavior cor relates with the limit states of finegrained soils. Over 80 ...