Showing papers in "Journal of Geotechnical Engineering in 1986"
TL;DR: In this article, a simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principal stress at any point in the soil.
Abstract: Data are presented concerning the shear modulus and damping ratios of sands and gravelly soils as determined by laboratory and field tests. A simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principal stress at any point in the soil. Values for the modulus coefficient at low strains are suggested, and it is shown that these values for sands can be estimated from the standard penetration resistance of the sand. Values for gravels are generally greater than those for sands by factors ranging from 1.35–2.5. Suggestions are also made for determining the variation of shear modulus with shear strain and the damping ratios for both sandy and gravelly soils.
945 citations
TL;DR: In this paper, the authors compared the stress-strain response of a sand reinforced with continuous, oriented fabric layers as opposed to randomly distributed, discrete fibers, and found that both types of reinforcement improved strength, increased the axial strain at failure, and in most cases reduced post-peak loss of strength.
Abstract: Triaxial compression tests were run to compare the stress-strain response of a sand reinforced with continuous, oriented fabric layers as opposed to randomly distributed, discrete fibers. The influence of various test parameters such as amount of reinforcement, confining stress, and inclusion modulus and surface friction were also investigated. Test results showed that both types of reinforcement improved strength, increased the axial strain at failure, and in most cases reduced post-peak loss of strength. At very low strains (<1%) fabric inclusions resulted in a loss of compressive stiffness. This effect was not observed in the case of fiber reinforcement. The existence of a critical confining stress was common to both systems. Failure envelopes for reinforced sand paralleled the unreinforced envelope above this stress. Strength increase was generally proportional to the amount of reinforcement, i.e., the number of fabric layers or weight fraction of fibers, up to some limiting content. Thereafter, the strength increase approached an asymptotic upper limit. Fiber-reinforced samples failed along a classic planar shear plane, whereas fabric-reinforced sand failed by bulging between layers.
395 citations
TL;DR: In this paper, a simple correction factor is proposed as a tentative standard for the standard penetration test (SPT) based on data from future research, contingent on data collected from future studies.
Abstract: Several formulae and charts have been published for correcting the results of the standard penetration test (SPT) performed in sands for the effects of overburden pressure. However, depending on which published correction factor is used, very different interpretations may result. This paper attempts to clarify and resolve some of these differences, and proposes a simple correction factor as a tentative standard, contingent on data from future research.
373 citations
TL;DR: In this paper, the aging of quick clay after sampling, the remolded strength increases in samples maintained at constant water content, time effects in freshly densified or deposited sand, in which natural sand deposits can lose strength if disturbed but regain strength over time periods of weeks to months, and apparently sound lime-stabilized soil that swells and disintegrates starting a few years after construction.
Abstract: In spite of our present very advanced analytical capabilities, our present ability to predict actual field behavior is, in many cases, woefully inadequate. Four cases are described to illustrate one of the reasons why actual and predicted performances are sometimes so widely divergent—namely, failure to understand how a soil might respond over time to changed conditions. The four cases are: (1) The aging of quick clay after sampling, in which the remolded strength increases in samples maintained at constant water content; (2) time effects in freshly densified or deposited sand, in which natural sand deposits can lose strength if disturbed but regain strength over time periods of weeks to months; (3) apparently sound lime‐stabilized soil that swells and disintegrates starting a few years after construction; and (4) the failure of excess pore pressures to dissipate as predicted during the consolidation of soft clays. Study of each of these problems has led to an understanding of the responsible phenomena an...
297 citations
TL;DR: In this article, the authors present experimental results obtained for the distribution of the active stresses due to a sand backfill behind a rigid wall rotating about the top of the wall, and compare the active earth pressure distributions for three different wall movement modes: rotation about top, rotation about heel, and translation.
Abstract: In this paper the writers first present experimental results obtained for the distribution of the active stresses due to a sand backfill behind a rigid wall rotating about the top. The experimental evidence shows that the stress distribution is nonlinear and that, due to arching, the stress near the top of the wall increases beyond the level of the at‐rest stress. Consequently, the point of application of the lateral thrust is much higher than one‐third from the wall base. Arching effects increase with increasing soil density. Secondly, comparisons of the active earth pressure distributions are made for three different wall movement modes: (1) Rotation about top; (2) rotation about heel; and (3) translation. Total active resultant forces and the points of application of these forces are summarized.
195 citations
TL;DR: In this paper, a fine-grained soil was mixed with 1% by volume of 20mm-long synthetic fibers and the results showed that the fibers had a somewhat greater strength and strain to failure with fibers in comparison with specimens without fibers.
Abstract: A fine-grained soil was mixed with 1% by volume of 20-mm-long synthetic fibers. Laboratory specimens were compacted at various water contents and tested in unconfined compression. Specimens compacted wet of optimum were found to have somewhat greater strength (up to 25%) and strain to failure with fibers in comparison with specimens without fibers. Dry of optimum, there was little or no benefit from the fibers. Nylon and polypropylene fibers gave similar results. Mixing the fiber into the soil was difficult; especially for the smaller (less than 0.20 mm diameter) fibers.
181 citations
TL;DR: In this article, a seismic cone penetration test (SCPT) was proposed for determining stratigraphic strength and modulus information in a single sounding using a small rugged velocity seismometer incorporated into an electronic cone penetrometer.
Abstract: A new test, called the seismic cone penetration test (SCPT) is described. A small rugged velocity seismometer has been incorporated into an electronic cone penetrometer. The combination of the seismic downhole method and the CPT logging provide an extremely rapid, reliable, and economic means of determining stratigraphic strength and modulus information in one sounding. Results using the seismic cone penetration test are presented and compared to conventional in situ techniques.
175 citations
TL;DR: In this article, a method to compute the effective dynamic stiffnesses (K¯) and dashpots (C) of arbitrarily shaped, rigid surface machine foundations placed on reasonably homogeneous and deep soil deposits is presented.
Abstract: The paper presents a method to compute the effective dynamic stiffnesses (K¯) and dashpots (C) of arbitrarily shaped, rigid surface machine foundations placed on reasonably homogeneous and deep soil deposits. The method is based on a comprehensive compilation of a number of analytical results, augmented by additional numerical studies and interpreted by means of simple physical models. All results are offered in the form of easily understood dimensionless graphs and formulae, covering the six modes of vibration and a wide range of frequencies, for both saturated and unsaturated soils. Comparisons are made with the widely used equivalent circle approximation. The proposed method is applicable to a variety of area foundation shapes, ranging from circular to strip and including rectangles of any aspect ratio as well as odd shapes differing substantially from rectangle or circle. The results confirm that both frequency and foundation shape may significantly affect K¯ and C. Insight is gained into the mechanics of radiation damping and a general conclusion is drawn regarding its magnitude at high frequencies for different foundation shapes and vibrational modes. The practical application of the method is illustrated with a specific example, while a companion paper presents supporting experimental evidence from model tests.
155 citations
TL;DR: Torsional resonant column tests are conducted to study the effect of artificial cementation on low strain dynamic properties of Monterey No. 0 sand as mentioned in this paper. But the results of these tests are limited.
Abstract: Torsional resonant column tests are conducted to study the effect of artificial cementation on low strain dynamic properties of Monterey No. 0 sand. Artificially cemented specimens are prepared using 1, 2, and 4% Portland cement by weight. Specimens were tested after 14 days of curing. It is determined that maximum shear modulus increased and damping ratio decreased with an increase in the degree of cementation. The maximum dynamic shear moduli increased due to corresponding increases in stiffness coefficients. The stiffness ratio defined as the stiffness of cemented to uncemented specimens varied with the degree of cementation and density. Dense specimens rendered higher stiffness ratios. The stiffness ratio was correlated to unconfined compressive strength and the cohesion intercept from CIU tests. Degradation of modulus ratio with strain ratio depended upon both the degree of cementation and density. Decay of modulus was more predominant in stiffer specimens. Cementation led to a decrease in damping ra...
150 citations
TL;DR: In this article, a rational interpretation method for estimating the in situ consolidation and permeability characteristics of clays from pore pressure dissipation measurements after piezocone penetration is presented.
Abstract: A rational interpretation method for estimating the in situ consolidation and permeability characteristics of clays from pore pressure dissipation measurements after piezocone penetration is presented. The method is based on linear consolidation analyses and initial pore pressure distributions calculated by the strain path method for undrained penetration in Boston blue clay (BBC). Extensive dissipation measurements in BBC are consistent with predictions for two cone angles and various locations of the porous element. Backfigured values of the coefficients of consolidation and permeability are in reasonable agreement with laboratory and field performance data.
144 citations
TL;DR: In this article, the peak and residual compaction induced lateral earth pressures were evaluated in free field or adjacent to vertical, non-reflecting soil in the free field and adjacent to a vertical, nondeflecting soil.
Abstract: Analytical models and procedures are presented for the evaluation of peak and residual compactioninduced lateral earth pressures either in the free field or adjacent to vertical, nondeflecting soil...
TL;DR: In this article, the undrained behavior of saturated sand in monotonically loaded triaxial tests is discussed using steady state concepts, and the relations among various drained and undrained strength envelopes are first examined.
Abstract: The undrained behavior of saturated sand in monotonically loaded triaxial tests is discussed using steady state concepts. The relations among various drained and undrained strength envelopes are first examined. These monotonic loading concepts are then used to explain the effect of static shear stress, τS, on the undrained cyclic triaxial strength of anisotropically consolidated specimens. The effect of τS, is found to depend on whether a specimen is contractive, dilative or partially‐contractive. For contractive specimens, the cyclic strength always increases with increasing τS, if there is stress reversal and if the peak shear stress, τp, is smaller than the steady state shear strength, Sus. This effect of stress reversal on cyclic strength is explained by the larger cyclic strains generated in the extension part of the cycle. However, if τp>Sus, cyclic strength can increase or decrease with increasing τs; if there is no shear stress reversal, the cyclic strength always decreases with increasing τS. For...
TL;DR: In this paper, the slope stability of some offshore environments can be evaluated by using conventional acoustic profiling and short-core sampling, followed by laboratory consolidation and strength testing, and the test results are synthesized by using normalized-parameter techniques.
Abstract: The slope stability of some offshore environments can be evaluated by using only conventional acoustic profiling and short-core sampling, followed by laboratory consolidation and strength testing. The test results are synthesized by using normalized-parameter techniques. The normalized data are then used to calculate the critical earthquake acceleration factors or the wave heights needed to initiate failure. These process-related parameters provide a quantitative measure of the relative stability for locations from which short cores were obtained. The method is most applicable to offshore environments of gentle relief and simple subsurface structure and is not considered a substitute for subsequent site-specific analysis. Four sites off California and Alaska contain acoustically defined sediment failures. Calculated critical earthquake factors in these failed areas are typically lower than in adjacent unfailed areas, a result lending credence to the method.
TL;DR: In this article, an analytical method has been proposed to predict the ultimate uplift capacity of piles embedded in sand, taking into consideration the length, diameter, and surface characteristics of piles and the soil properties.
Abstract: An analytical method has been proposed to predict the ultimate uplift capacity of piles embedded in sand. The method takes into consideration the length, diameter, and surface characteristics of piles and the soil properties. Typical charts for evaluation of average skin friction values for piles are presented through figures in dimensionless quantities. Critical depth of embedment beyond which the average skin friction attains a constant value depends not only on the relative density of sand but significantly on pile surface characteristics. Reasonable agreement has been observed between the measured and predicted values of uplift capacities. Among the available methods the proposed analysis predicts more realistic values of uplift capacities.
TL;DR: In this article, a rational interpretation method was developed to estimate the consolidation and/or permeability of the soil during steady cone penetration, and linear consolidation solutions were presented to analyze dissipation data in clays.
Abstract: Piezocone measurements during steady cone penetration provide valuable soil-profiling and soil-identification data. The potential of the piezocone as a soil-exploration tool can be significantly enhanced if the pore-pressure decay that takes place after interrupting penetration can be interpreted to estimate the consolidation and/or permeability of the soil. This paper provides the necessary theoretical background to develop a rational interpretation method and presents linear consolidation solutions to be used in analyzing dissipation data in clays. Results show the two-dimensional aspects of the problem and evaluate the effects of clay anisotropy, cone angle, porous sensing element location, linear coupling, mesh size, and resolution as well as sensitivity of predictions to soil variability and measurement errors.
TL;DR: In this article, pore size characteristics and permeability of compacted sandy soils are described, and samples of mixtures of Ottawa sand and kaolinitic clay were prepared by kneading compaction and plu...
Abstract: Studies of the pore size characteristics and permeability of compacted sandy soils are described. Samples of mixtures of Ottawa sand and kaolinitic clay were prepared by kneading compaction and plu...
TL;DR: In this paper, the authors conclude that concentrated leaks occur commonly through the impervious sections of embankment dams by hydraulic fracturing without being observed, even in dams which are not subjected to unusually large differential settlement.
Abstract: There is now sufficient evidence to conclude that concentrated leaks occur commonly through the impervious sections of embankment dams by hydraulic fracturing without being observed, even in dams which are not subjected to unusually large differential settlement. Usually these concentrated leaks do not cause erosion, either because the velocity is too low or because the leak discharges into an effective filter. Subsequently the leakage channel is squeezed shut by swelling or softening of the embankment material forming the walls of the crack. In the typical case no measurable leakage emerges downstream and there is no other indication that a concentrated leak developed and was subsequently sealed. This action probably occurs to some degree in most embankment dams.
TL;DR: In this paper, hydraulic conductivities were measured on three compacted clays that were permeated with water, methanol, and heptane in rigid-wall and flexible-wall permeameters.
Abstract: Hydraulic conductivities were measured on three compacted clays that were permeated with water, methanol, and heptane in rigid-wall and flexible-wall permeameters. The type of permeameter had little effect when the soils were permeated with water. However, rigid-wall permeameters generally yielded much higher hydraulic conductivities than flexible-wall cells when the soils were permeated with organic compounds. Differences in effective stress and confinement along the sidewall of the test specimen are thought to be responsible for the different patterns noted. Permeation of water-saturated clay with heptane caused the hydraulic conductivity to drop to practically zero because of surface tension effects at the water-heptane interface. There appeared to be a threshold hydraulic gradient below which the hydraulic conductivity to heptane was zero. The results of this study show order-of-magnitude differences in hydraulic conductivity depending on testing apparatus and procedures.
TL;DR: In this paper, cyclic triaxial tests were performed on a well-graded railroad ballast with a maximum particle size of 38 mm (1.5 in.), and the cumulative permanent axial strains that developed, for constant-amplitude loadings, were found to be dependent upon the permanent strain after one cycle of loading, the loading magnitude, and the number of applied loading cycles.
Abstract: Cyclic triaxial tests were performed on a well‐graded railroad ballast with a maximum particle size of 38 mm (1.5 in.). Samples were compacted in a split mold to reproduceable density states and subjected to repeated applications of compressive axial stresses. The cumulative permanent axial strains that developed, for constant‐amplitude loadings, were found to be dependent upon the permanent strain after one cycle of loading, the loading magnitude, and the number of applied loading cycles. Staged tests were conducted in which a sequence of variable loads was applied to the same sample. For these variableamplitude tests, the final permanent strains were independent of the order of the applied loadings. A superposition method is presented to characterize the mixed loading conditions. The results for the variable‐amplitude tests indicated that the maximum load controlled the permanent strain development, with negligible additional strains developing after returning to a lower repeated stress level. Partial u...
TL;DR: In this paper, the potential of millisecond delays in blast-densification of saturated cohesionless sand was investigated using a large liquefaction tank to prepare and contain the sand.
Abstract: Laboratory tests have been conducted to investigate the potential of millisecond delays in blast‐densification of saturated cohesionless sand. A large liquefaction tank was used to prepare and contain the sand. Commercially available blasting caps were used as the explosive. Cone penetration tests and sand surface elevation changes were measured. In addition to lowering the peak body wave ground motions, densification with millisecond delays was shown to be comparable to densification by a single large blast with a total charge weight equal to the sum of the delays. Increases in cone penetration resistance were measured 10–40 cm (4–16 in.) from the charges. A gradual increase in point resistance was observed with time after each blast. The increase in penetration resistance may be attributed to gradual improvement of intergranular bonds and dissipation of explosion created gases.
TL;DR: In this paper, a method for evaluating the earthquake-induced permanent displacements for sliding blocks is presented, given the distributions of the limiting accelerations and the ground motion parameters, this method will give the probability distribution of the permanent displacement.
Abstract: A method is presented for evaluating the earthquake‐induced permanent displacements for sliding blocks. Given the distributions of the limiting accelerations and the ground motion parameters, this method will give the probability distribution of the permanent displacements. The mechanism by which the permanent displacements are induced in a step‐wise fashion is incorporated. In addition, an equivalent stationary motion model is employed for ground accelerations. To facilitate general applications, conditional distributions for permanent displacements are also given based upon site soil conditions. A numerical example is also worked out in detail.
TL;DR: In this article, an analytic expression has been developed that enables the shear strength to be determined using the empirical failure criterion developed by Hoek and Brown, along with elasticity theory and basic mathematical concepts.
Abstract: In this work, an analytic expression has been developed that enables the shear strength to be determined using the empirical failure criterion developed by Hoek and Brown. Applying this new hypothesis, along with elasticity theory and basic mathematical concepts for obtaining the failure envelope of a family of failure circles, the shear strength has been determined to be such that τα=f(σα,σc,m,s), where σα=the normal stress on the discontinuity, σc the uniaxial compressive strength of the intact rock and the parameters m and s are constants dependent upon the properties of the rock. An expression of this type will help us develop new methods of analysis of slope stability and support of galleries, design of anchor support systems in rock masses, estimation of the skin friction of poor quality rock in driven pile foundations, as well as in other innumerable related areas of geotechnology.
TL;DR: In this paper, the role of soil arching in discrete pile retaining walls is examined and an information base for rational design is provided, which can be used to determine the influence of and relationships between the essential parameters.
Abstract: Recently soil arching theory has been extended to the study of forces and stresses exerted by a yielding soil mass against discrete piles embedded in a slope and extending into a firm, non‐yielding base. Many uses of discrete pile retaining wall systems exist in current geotechnical practice. In each case, soil arching has been relied upon to some extent as a means of stabilization without concise information about the required spacing of the stabilization piles. This lack of information requires a design engineer to err on the conservative side, and to place the piles closer together than they need be. This study examines the role of soil arching in discrete pile retaining walls and provides an information base for rational design. The present research objective is to experimentally model soil arching action between piles, to determine the influence of and relationships between the essential parameters, and to compare predictions from several new arching theories to experimental model results. The result...
TL;DR: A number of currently employed mathematical formulations used in modeling onedimensional quiescent consolidation of phosphatic waste clay ponds are reviewed in this article, as well as theoretical and practical results.
Abstract: A number of currently employed mathematical formulations used in modeling onedimensional quiescent consolidation of phosphatic waste clay ponds are reviewed. It is shown theoretically, as well as t...
TL;DR: In this paper, a well planned and carefully executed program of oedometer tests on high quality undisturbed samples is shown to provide considerable practical information about the soil properties of a natural, v...
Abstract: A well planned and carefully executed program of oedometer tests on high quality undisturbed samples is shown to provide considerable practical information about the soil properties of a natural, v...
TL;DR: In this article, the dynamic impedances of a vertically or torsionally excited viscoelastic soil layer with a thin disturbed zone around the edge of a central circular hole are evaluated and compared, over a range of parameters, with those obtained by a previously proposed, simpler analysis in which the mass of the disturbed zone is neglected.
Abstract: The dynamic impedances of a vertically or torsionally excited viscoelastic soil layer with a thin disturbed zone around the edge of a central circular hole are evaluated and compared, over a range of parameters, with those obtained by a previously proposed, simpler analysis in which the mass of the disturbed zone is neglected. It is shown that the results of the two approaches may differ significantly, and that the simpler solution should be used only with the greatest possible care.
TL;DR: In this article, analytical models and a finite element analysis methodology are presented for evaluation of compactioninduced soil stresses and resulting soilstructure interaction effects, and the results show that compaction induced soil stresses are associated with soil stabilities.
Abstract: Analytical models and a finite element analysis methodology are presented for evaluation of compactioninduced soil stresses and resulting soilstructure interaction effects. These analytical methods...
TL;DR: In this paper, the analytical method of the companion paper was used to verify the analytical results of the analysis, for circular, square and rectangular base shapes with aspect ratios up to 6, and including vertical, torsional and coupled swaying-rocking oscillations.
Abstract: Results of twenty-one free vibration tests on surface model footings on moist sand having different base shapes and about equal base area have been reported. These tests are used here to verify the analytical method of the companion paper, for circular, square and rectangular base shapes with aspect ratios up to 6, and including vertical, torsional and coupled swaying-rocking oscillations. Close agreement is found between predicted and measured frequencies in all cases, and also between damping ratios in vertical and torsional vibration. The experiments provide strong support for the vertical and torsional radiation damping graphs developed in the companion paper, including verification of the increased damping ratios predicted for the longest footings. The accord is also reasonably good for damping in those swaying-rocking tests in which rocking and material damping are dominant and the overall damping ratio is about 3%. However, the method overpredicts the measured swaying-rocking damping ratios in those tests in which swaying and radiation damping are also important, and for which larger damping ratios are predicted (4% to 9%). This discrepancy between half-space predicted swaying-rocking damping and measured values is explained by the effect of boundary wave reflections on the test results.
TL;DR: In this paper, the results of dynamic lateral load tests on a cantilevered mass supported by a single 10.75-in. (273-mm) diameter steel pipe pile embedded in stiff, overconsolidated clay are presented.
Abstract: The results of dynamic lateral load tests on a cantilevered mass supported by a single 10.75-in. (273-mm) diameter steel pipe pile embedded in stiff, overconsolidated clay are presented. These tests were conducted to provide a basis for evaluation of mathematical models that predict the relatively low-frequency dynamic pile response that is representative of systems in which the primary resonance frequency is controlled by the mass and stiffness of the superstructure. Frequency sweep shear forcing functions were applied at the top of the mass, which simulated a simple structure. The responses of the pile-supported mass, points on the embedded pile, and points in the supporting soil were recorded to determine frequency response functions. Frequency response functions between the applied load and pile cap-mass were then examined to aid in the identification of the pile–soil system parameters which most strongly influence response. The measured pile cap frequency response function peak amplitude was 0.0022 in./lb (0.0126 mm/N), or about ten times the static flexibility, and the resonance frequency was approximately 2.2 Hz.
TL;DR: A computer-based analysis of the runout dynamics of the Madison Canyon rockslide of August 17, 1959 is reported in this article, where three levels of computer representation of the flow are considered.
Abstract: A computer-based analysis of the runout dynamics of the Madison Canyon rockslide of August 17, 1959, is reported. Three levels of computer representation of the flow are considered. First is a representation of the actual canyon profile, where the model assumes incompressible linear viscous flow. Second is a horizontal profile in which gravitational forces are input by components, and again the flow is approximated by a single viscosity model. Third is a horizontal profile, for which a two viscosity model approaching a Bingham material representation is used. Results of each model are compared to actual slide runout, debris distribution, and maximum speed of the flow. The biviscous model, which depicts an active basal flow layer, also has physical characteristics consistent with measurements made of the Madison Canyon slide following the event.