The potential for liquefaction below a building is often evaluated by treating the soil as if it were in the free field. A summary of available field case histories, shaking table model tests, and centrifuge model tests is presented; this clearly indicates that the excess pore pressure distribution near a building can be much different than in the free field. Modifications to the typical free‐field liquefaction analysis procedure to account for changes in the vertical stress, horizontal shear stresses, and overconsolidation ratio due to a structure are suggested. Soil‐structure interaction effects on the potential for liquefaction are also examined. Comparisions with free‐field conditions suggest that the potential for liquefaction damage may be greater or lesser beneath a building depending on the building type and soil density. Sands below short‐period, low‐rise structures appear to have higher potential for liquefaction than predicted by simplified methods while sands below tall, long‐period structures appear to have lower liquefaction potential than sands in the free field.

The response of single piles to vertically and obliquely incident SH, SV, and P waves is obtained by a hybrid boundary element (BEM) formulation. The piles are idealized as compressible beam‐columns and the soil, as a hysteretic viscoelastic half‐space. A new Green function corresponding to the displacement field due to a dynamic point force in the interior of a semi‐infinite solid has been developed and implemented. The governing differential equations of motion for the piles are solved exactly for distributed periodic loading intensities. These solutions are coupled with the BEM numerical solutions for the soil domain by satisfying equilibrium and displacement compatibility at the pile‐soil interface. The salient features of the seismic response are identified in several nondimensional plots that encompass a wide spectrum of geometrical and material parameters commonly encountered in practice. The results of the analyses compare favorably with the limited data available in the literature.

A new method is proposed for elucidating, formulating, and predicting the axial capacity of friction piles in moderately overconsolidated clays $(1\le \mathrm{OCR}\le 4)$ within a systematic and rational framework. The paper focuses on single, vertical, rigid, and cylindrical piles driven in deep deposits which exhibit normalized behavior. The normalized limiting skin friction, $\beta (=f_s/{\sigma }_{\mathrm{vo}}^{\prime })\text{,}$ during rapid monotonic undrained axial loading is written as the product of a lateral earth‐pressure coefficient, $K_c(={\sigma }_{\mathrm{hc}}^{\prime }/{\sigma }_{\mathrm{vo}}^{\prime })$ at the end of soil consolidation, which follows pile installation, and a skin‐friction ratio, $\rho (=f_s/{\sigma }_{\mathrm{hc}}^{\prime })\text{.}$ Important factors affecting $K_c$ are shown to include the overconsolidation ratio (OCR) of the clay and its sensitivity. The friction ratio, ρ, is not sensitive to the in situ OCR of the deposit and corresponds to the normalized peak‐strength ratio, $c_u/{\sigma }_{\mathrm{vc}}^{\prime }\text{,}$ in undrained direct simple shearing of the clay at an $\mathrm{OCR}=1.2(\pm 0.1)\text{.}$

Large deformation consolidation computer programs are being used extensively by Florida phosphate mining industries for compliance with regulatory activities. Accordingly, a prediction symposium was held to provide a forum of idealized boundary conditions that would demonstrate areas of agreement and the limitations of various computer programs. Nine different program users provided predictions of pond elevation histories and of pore pressure and void ratio profiles after one year for four different waste clay disposal scenarios. Programs to estimate quiescent consolidation of waste ponds having uniform initial void ratios, with or without surcharge loading, and continuous and/or stage filling are available, but less available are programs that handle nonuniform void ratios and/or multilayer conditions with different nonlinear compressibility properties. Presently, piecewise linear programs appear best suited to accommodate the latter. In general, final height predictions for all scenarios were in agreement, but height predictions at early times were found sensitive to program input (i.e., number of time steps or layers). Agreement among void ratio and pore pressure profiles generally improved with depth. Least agreement was for stage filling and nonuniform initial void ratio and multilayer conditions.

The liquefaction potential of saturated cohesionless deposits in Charleston, South Carolina, was evaluated probabilistically. The map is a combination of liquefaction susceptibility and liquefaction opportunity. Critical acceleration, the measure of liquefaction susceptibility, was obtained using the simplified empirical method developed by Seed and his coworkers. This method is based on the empirical relationship between standard penetration resistance and cyclic stress ratio. The liquefaction opportunity is determined by modeling zones of different seismic threat. The probability of liquefaction is computed by comparing the acceleration at the site to that required to cause liquefaction. Results are expressed as maps of zones of different risk levels and through a normalized liquefaction resistance index of the probability of liquefaction. Over 200 boring logs from peninsular Charleston were examined, showing the soil variability in the study area. This variability is due to the large amount of filling that took place over 300 years to reclaim land from the sea, swamps, and creeks that covered much of the original peninsula. The results indicate peninsular Charleston has a moderate liquefaction potential.

The finite element computer program RDPIL.FOR for laterally loaded piles in a viscoelastic layered soil is developed. The program uses a Maxwell model to accommodate the initial elastic subgrade modulus, which is independent of time. This necessitates the initial subgrade modulus k (preferably extrapolated from pile tests), Poisson's ratio μ, and creep parameters n, b, and ${\sigma }_c$ (obtainable from either pressuremeter or triaxial test results). Finally, the validity of the proposed method is checked against the results of pile tests that have been carried out in the 1970s at Inuvik, N.W.T., and Dawson City, Yukon.

Soil properties and their behavior, apart from stress history, are influence markedly by physicochemical characteristics of the constituent clay and nonclay minerals and their relative proportions. Atterberg limits and Skempton's colloidal activity, which are simple quantitative parameters, reflect the composite effects of the soil constituents and their interactions with pore fluid. Micromechanistic interpretations of these parameters have been provided in this paper. It has been shown that, in general, the liquid limit of fine‐grained soils reflects the physicochemical potential and that each of the factors of Skempton's colloidal activity are interdependent. It has been illustrated that property correlations with colloidal activity, as well as with Atterberg limits, result in involved interrelationships due to the interdependence of the parameters.

A testing program was established to determine the accuracy and efficiency of in situ permeability testing equipment. The sealed single‐ring infiltrometer, sealed double‐ring infiltrometer, and air‐entry permeameter were evaluated in this study. The theoretical basis for each of these tests was examined and their testing procedures outlined. The accuracy and ease of use of these devices was demonstrated by full‐scale tests under controlled field and laboratory conditions. The field permeability tests were conducted on a residual soil‐liner test pad installed at a site near Jamestown, California. The laboratory permeability tests were conducted on a prototype liner composed of uniform Ottawa sand and sodium bentonite. This material was mixed, moisture‐conditioned, and compacted into reinforced wooden frames. The in situ permeability test results were verified with low‐gradient, back‐pressure saturated triaxial permeameter tests conducted on undisturbed 101.4 mm (4 in.) cored and remolded samples. This evaluation shows that good agreement can be obtained between in situ field and laboratory triaxial permeability tests results. In addition, changes in hydraulic conductivity of hydrating sand‐bentonite with time observed in the in situ tests, closely approximated the results obtained in the triaxial permeability tests. This evaluation also demonstrated that considerable care was required setting up and conducting in situ permeability tests, in order to obtain reliable results.

The methods currently used for the design of reinforced earth walls with extensive geosynthetic reinforcements can be broadly classified as: (1) Working stress design methods that basically rely upon restrictive assumptions with regard to the state of stress in the soil; and (2) limit equilibrium methods that essentially use conventional slope stability analyses, modified to account for the reinforcement effect of the global stability of the reinforced soil mass. Neither of these approaches considers the fundamental requirements of strain compatibility between the reinforcement and the soil nor can they provide any evaluation of the effect of soil dilatancy and extensibility of the reinforcement on the mobilized tension forces and structure stability. This paper presents a strain compatibility design approach that is fundamentally based on the analogy between the plane strain shear mechanism that develops along a potential failure surface in the actual structure and the response of the reinforced soil material to simple shearing. The soil‐reinforcement load transfer model used in this analysis allows for the evaluation of the effect of soil dilatancy and extensibility of the reinforcement on the generated tension forces and on the probable location of the potential failure surface.

The steady state line (SSL) of a soil is defined as the relationship between a soil's void ratio (or density) and its residual ``steady state'' or critical state strength. Recent testing of very low density sand samples indicates that the steady state line approaches a limiting maximum void ratio, representing a considerable departure from the assumption of a linear relationship between the logarithm of steady state strength and void ratio employed in many constitutive models. This recent testing suggests that a limiting minimum density exists, below which a sample will show no steady state shear strength at all. Moreover, this limiting density appears to occur at a relative density of $D_r=>$0%–10%. This technical note presents data regarding this apparent limiting density, based on the results of laboratory testing performed by four researchers on three different sands.