This paper presents the results of a physical and numerical model study of impounded gold mine tailings produced at Boddington Gold Mine in Western Australia. The centrifuge modeling technique is used to replicate the staged filling of the tailings impoundment to assess both the short‐ and long‐term consolidation behavior of the tailings. At the time of testing, filling of the impoundment is nearly complete, and field data are available for comparison at various stages in the model construction. Numerical analyses of the centrifuge tests are also performed and found to give encouraging results. The good agreement between the field and centrifuge model data and the numerical results allows predictions of the future behavior of the tailings to be made with a high degree of confidence.

Two‐ and three‐dimensional finite element (FE) analyses are performed to investigate the influence of nonlinear soil behavior on the dynamic response of harmonically excited rigid foundations. Lateral, rocking, and torsional vibration modes are considered. An elastoviscoplastic constitutive model with kinematic hardening is assumed for the foundation soil, and computations are done implicitly in the time domain. The foundation responses for lateral, rocking, and torsional modes are characterized by increased vibrational amplitudes due to material stiffness degradation. Furthermore, resonance frequencies are created that resemble those observed for vertically oscillating finite‐size foundations. Nonlinear soil effects are shown to be dominant over a wide range of excitation frequencies for foundations vibrating in torsional and lateral modes. In contrast, nonlinear soil effects are shown to be dominant over a much narrower range of excitation frequencies for the rocking mode. The methodology presented in this paper is useful for nonlinear vibration and transient soil‐structure interaction (SSI) analysis.

Model tests in a laboratory flume were performed to verify certain hypotheses put forward to explain steep riprap behavior observed in the field at several embankment dam sites. The laboratory study has focused on riprap degradation under wave attack, and on the influence of fine blocks incorporated into riprap. Unlike flatter riprap, steep riprap is characterized by a low rate of damage until a point of acceleration, after which damage progresses rapidly. At that stage, damage is characterized by sliding and crumbling, which results in an upward propagation of damage toward the crest. The inclusion of a portion of small blocks into the riprap significantly reduces the stability of steep riprap. This detrimental effect is gradually reduced as the riprap slope becomes flatter.

Collapsible coarse‐grained deposits present a particular challenge in both identification and characterization. This is particularly the case with collapsible gravels, where sampling is a practical impossibility. Six case histories involving collapsible gravels are presented that indicate the general characteristics of these materials and the methods that have been employed for evaluating their properties. Laboratory and field evidence suggests that the fine‐grained matrix is responsible for the collapse phenomenon and that as little as 5–20% fines may be sufficient to produce collapsible behavior. In situ tests that have shown some promise include plate‐load bearing tests and prebored pressuremeter tests conducted first under dry natural conditions and then following wetting. Experience clearly shows that coarsegrained soils in a geologically susceptible environment can collapse upon wetting even though they may have high densities and very high SPT blow counts.

The phenomenon of earthquake fault rupture propagation through soil is quite complex and is not well understood at this time. This paper presents the results of an integrated investigation of this problem. Insights are developed from the examination of surface fault rupture field case histories, laboratory physical model tests, and physical analogies to the earthquake fault rupture process. Field observations and experimental results illustrate the “typical” patterns of behavior developed in the soil overlying a base rock fault displacement. Evidence suggests that differential movement across the distinct fault rupture dissipates as the fault rupture propagates toward the ground surface through unconsolidated earth materials, and that the characteristics of the soil overlying the bedrock fault strongly influence the observed earthquake fault rupture propagation behavior.

An improved understanding of earthquake fault rupture propagation through saturated clay would assist engineers in siting and designing facilities to be constructed in regions where cohesive soils overlie potentially active faults. The results from numerical analyses suggest that the finite‐element method can be applied to this class of problem provided that the soil's nonlinear stress‐strain behavior is adequately modeled. It was found that the height of the shear rupture zone in the overlying saturated clay soil at a specified base rock fault displacement depends primarily on the soil's failure strain. As the clay's failure strain decreases, the shear rupture zone in the clay overlying the bedrock fault propagates further at a specified base displacement. Other material parameters such as soil shear strength and stiffness also affect the fault rupture process, but not to the extent of failure strain. The orientation of the shear rupture zone through the soil depends largely on the orientation of the underlying bedrock fault plane.

The 1988 $M_s\approx 6.8$ earthquake in Armenia resulted in more than 40,000 human casualties and massive destruction of the northwestern region of Armenia. The effects of local geology and soil conditions upon the earthquake‐induced damage were analyzed and reported by the writers in other publications in the ASCE Geotechnical Journal. This paper presents data and analysis of liquefaction and liquefaction‐induced embankment failure case histories, the significance of which stems from the fact that the liquefied sands had a high gravel content (up to 50%). There are only a few well‐documented field observations of liquefaction of gravels and gravelly sands, and the information presented in this paper augments this limited database. Our analyses lead to the conclusion that loose to medium‐dense gravelly soil deposits that are not confined against drainage can withstand large (0.5 g–1.0 g) peak ground accelerations without liquefying. However, a mere 30 cm thick impermeable topsoil can impede drainage, thus causing liquefaction of such soils leading to significant deformations and lateral spreading. The residual shear strength of the gravelly soils investigated (with field SPT of ≈36 blows/m (12 blows/ft)) was back‐estimated to range between 5 to 13 kPa (100– 260 psf), values comparable to the residual shear strength of loose clean sands. The observations and conclusions from liquefaction of gravelly soils in Armenia compare well with the well‐documented cases from the 1983 Borah Peak, Idaho, earthquake.

A torsional‐ring‐shear apparatus and test procedure are described for measuring soil/geosynthetic and geosynthetic/geosynthetic interface strengths. Typical interface strengths are presented for a double‐composite liner system and the relevancy of ring‐shear strengths is illustrated using the slope failure at the Kettleman Hills Waste Repository, Kettleman City, Calif. The results of undrained ring‐shear tests show that for a clay/geomembrane interface: (1) Interface strength depends on plasticity and compaction water content of the clay, and the applied normal stress; (2) interface strengths measured with the torsional‐ring‐shear apparatus are in excellent agreement with back‐calculated field strengths; and (3) peak and residual interface failure envelopes are nonlinear, and the nonlinearity should be modeled in stability analyses instead of as a combination of cohesion and friction angle. Design recommendations for interface strengths and stability analyses are also presented.

The results of this study show that the initial amount of swell and shrinkage for a clay compacted at a moisture content that was 6% wet of modified Proctor optimum was small. By allowing the compacted silty clay to cure, bonds were developed that further reduced the amount of initial swell and shrinkage. But after repeated wetting and drying cycles, the amount of expansion and shrinkage dramatically increased. Whatever effect compaction at a high moisture had was destroyed by wetting and drying cycles. In terms of practical applications, for a clay compacted over optimum and protected from wetting and drying cycles, aging may result in the development of bonds that substantially reduce long‐term swell. But if the compacted clay should dry out prior to placing the foundation, or if the clay is subjected to wetting and drying cycles, the beneficial effect of compacting the clay at a high moisture content will be destroyed, causing the soil to become significantly more expansive.