Consolidation settlements are often large and potentially damaging to structures. Estimating their magnitudes, and the rates at which they will occur, plays an important part in many civil engineering projects. At Bay Farm Island in San Francisco Bay, and Kansai International Airport in Japan, settlement magnitudes and settlement rates were of great importance for design. In these and similar cases it is important to understand what factors control the accuracy with which settlement magnitudes and settlement rates can be estimated. Accurate predictions of settlement magnitudes require accurate evaluations of clay compressibility and preconsolidation pressure. Accurate predictions of settlement rates require improved methods of anticipating whether embedded sand strata will or will not provide internal drainage; use of computer analyses to take into account important factors such as variations in $c_v$ within clay layers, nonlinear stress‐strain behavior, and nonuniform strain profile effects; and research to develop an improved model of clay compressibility that includes the effects of strain rate.

The paper describes a finite element technique that takes account of transient effects through a Biot analysis, enabling coupling of pore pressure variations to a nonlinear soil stress‐strain law. The algorithm can retrieve both drained and undrained solutions as special cases and has been verified against some existing solutions for time‐dependent failure of soil masses. The technique is then applied to the transient stability of excavated soil slopes. Long‐term instability is modeled by allowing the pore suctions, initially generated by the excavation process, to dissipate. For the slope under analysis, the coefficient $K_0$ is seen to have a significant influence on the undrained (short‐term) factor of safety, but little effect on the drained (long‐term) value.

Cemented carbonate (calcarenite) soils obtained from the North West Shelf of Australia were subjected to conventional and stress‐path triaxial tests. Natural calcarenite specimens were found to have wide variations of dry density and degree of cementation. These variations complicate interpretation of the test data, and need to be taken into account. To achieve this, it is suggested that tensile tests be performed on off‐cuts to estimate the degree of cementation. The responses of the natural calcarenite samples were found to be similar to other cemented and structured soils. Stress‐path tests were performed to investigate the shape of the yield locus. An elastic region was identified in which the shear modulus is constant and the bulk modulus varies linearly with mean effective stress. The cementation was found to increase the shear modulus and size of the yield locus, but to have little effect on the volumetric response.

This paper presents a total stress hybrid load‐transfer analysis for the response of pile groups in clay under either uniform or irregular cyclic loading. The soil mass may be arbitrarily layered and the nonlinear pile response is represented by a simple cyclic hyperbolic interface soil model. The reduction of shaft stress and accumulation of displacement are considered using the degradation of the soil secant modulus and shaft limiting stress. The shaft‐stress‐degradation factor is related to the cyclic strain in a hyperbolic form. The formulation of the analysis is relatively simple and the soil parameters required are relatively few and have physical meaning. The method is used to analyze the response of model pile‐group tests in soft clay under cyclic loading. In addition, a repeated monotonic loading on a full‐scale pile‐group field test in stiff overconsolidated clay is analyzed. The measured and computed results are in reasonably good agreement.

A new model is presented for characterizing the response of soils within the boundary zone around piles. The proposed concept provides for a continuous variation of soil properties with smooth transition into the outer zone; these properties alleviate the wave reflections from the interface between the two media. With this model the impedances of composite layers do not show the oscillations that are generally observed with the other boundary zone models that take account of the soil mass. The developed impedance functions are used in the dynamic analysis of a field problem involving vertical vibration of a single pile. Comparison of the theoretical predictions with the experimental data in this case indicates that inclusion of the boundary zone results in a reduction in the stiffness and damping for the pile‐soil system which in turn causes a reduction in the resonant frequencies and an increase in the resonant amplitude of piles. The results show that the proposed boundary zone model improves the agreement between the theoretical predictions and field‐measured data.

The uplift behavior of a shallow pipeline embedded in an elastoplastic medium is examined. An analytical solution for a beam on elastoplastic foundation is developed and a characteristic nondimensional load‐displacement and stress‐displacement relationship are presented. An approximate three‐dimensional (3D) solution is proposed that accounts for embedment and breakaway condition behind the pipeline making use of the load‐displacement curves developed for rigid anchors by Rowe and Davis in 1982. A comparison of these results with those obtained by 3D finite‐element analysis indicates that the simplified solution of a beam on elastoplastic foundation is a practical alternative for analyzing the uplift behavior of shallow pipelines. The approximate solution is also used to compare the behavior of a laterally loaded pile for which no separation or separation between the surrounding soil and the back of the pile is permitted as the load is monotonically increased. The results are presented in the form of nondimensional charts that permit hand calculations and rapid verification of structural design of the pipeline and piles.

A simple and practical approach is presented for the analysis of settlement of large pile groups embedded in an isotropic elastic half‐space with adequate accuracy but without the expense of a complete rigorous analysis. The approach is based on the superposition of the interaction factors between piles within a group. An approximate closed‐form analytical model is suggested to evaluate these interaction factors in homogeneous and nonhomogeneous soils. The values of the interaction factors computed by the analytical model agree reasonably well with those by the more rigorous boundary element approach. For pile groups with different pile configuration and pile compressibility, the theoretical solutions computed by the present approach are close to those by the boundary element or boundary integral approach. The settlements at working load level of two field pile groups embedded in stiff overconsolidated clay computed by the present approach are in reasonably good agreement with measured results.

A simple approach is described for the analysis of soil‐pile interactions under static and dynamic lateral loadings. The method uses variational calculus to obtain the governing differential equations of motion for the soil‐pile system under a harmonic concentrated load at the pile head with intensity $P_0$ and frequency ω. The pile is treated as a shear beam and the soil is assumed to be a linear elastic material. The solutions are based on a semianalytical and seminumerical approach, and are brought to a form that makes it possible to predict the dynamic displacements, stiffness, and damping for different soils and end conditions of the pile. Two cases are investigated: (1) A pile clamped to a rigid bottom underlying an elastic soil layer; and (2) a floating pile in an elastic half‐space. Numerical results are presented to illustrate the method and investigate the dynamic stiffness and damping of the soil‐pile system. The complex frequency responses of the soil‐pile system for typical values of the stiffness and hysteretic material damping of the soil are also presented. The numerical computations required for all solutions are modest.

Field loading tests of 10 short nondisplacement piles are analyzed using the writer's method of calculating the service load of long piles. The method is based on the analysis of over 200 field loading tests. A hyperbolic relation is assumed between the specific skin friction $q_s$ or toe pressure $q_t$ and the slenderness $L/D$ (length/diameter) of piles. The assumption is affirmed statistically to be acceptable for long piles (since $q_t\to 0\mathrm{for}L/D\to 0$). Using the method, an expression is deduced relating the skin friction share of the total service load to the pile slenderness. This forms a simple and uniform basis of the calculation of service load of piles of different slenderness and of soils of different consistencies and densities. The calculated service load of short piles was overestimated. This was explained by the toe pressure having been reduced by the heavy disturbance of the soil experienced at the pile toe by boring.

The potential exists for earthquake damage to water systems in many parts of the United States. There are two types of actions that water officials can take as part of a disaster or emergency response plan to minimize potential seismic effects to existing systems. These are physical damage mitigation and impact mitigation. In the case of impact mitigation, responsible officials need, among other things, a method for estimating the amount of expected seismic damage. This paper examines pipeline damage using data found in the literature and additional data as well. Results indicate that analytical estimates do not yet cover a broad enough range of damage mechanisms to be useful to water officials in estimating seismic wave propagation damage to buried pipelines. However, analytical procedures that quantify damage in terms of relative axial extension or axial compression force at a joint may prove useful in establishing design criteria for seismically resistant pipe.