A revised method is proposed for the analysis and design of cantilever retaining walls in homogeneous cohesionless soil. Like the current limit-stage design methods, the revised method is based on assumed linear pressure distributions but does not require the artificial simplifications inherent in those methods. Furthermore, these pressure distributions provide equilibrium without being directly dependent on assumed limit states in the passive earth support regions. They are dependent, however, on one empirical parameter for which a suitable value is determined, from the results of centrifuge model tests, within very narrow limits. The revised method gives critical depths of excavation closer to those observed in centrifuge tests than the current methods, and it is shown to yield complete bending moment distributions, with magnitude and position of maximum bending moments reasonably close to those observed. Finally, simple equations and design curves are presented to facilitate safe design, their use is illustrated with a typical example, and comparisons are made with the current methods.

The interactions between the solid and fluid phases of saturated porous media are due to inertial, viscous, and mechanical coupling. In particular, viscous coupling plays a key role because it makes wave propagation dispersive. The effects of viscous coupling on harmonic problems were described in detail by Biot, but the implications in transient problems have not been fully analyzed. Therefore, a detailed analysis is carried out on the effects of viscous coupling on the mechanics of transient wave propagation, by considering the propagation of simple shaped driving pulses (a step pulse, a single sine, and a single triangle), for both constant and frequency-dependent viscous coupling. Particular attention is paid to the interpretation of dynamic soil test measurements, because of their importance in the current practice of soil investigation, both in laboratory and in situ. Results show that it is possible to identify two extreme kinds of transient behavior: in the first, the porous medium behaves as a two-phase medium in which the velocity of propagation corresponds to null viscous coupling; in the second, the behavior corresponds to a one-phase medium with velocity of propagation corresponding to infinite viscous coupling. There is a gradual transition between these two extreme behaviors, but it extends for quite a narrow range of values of travel length and of the coefficient of permeability for a given frequency content of the driving pulse. Such conclusions are very useful in the interpretation of dynamic measurements and should enhance the comprehension of the mechanics of dispersive wave propagation in saturated porous media.

Laboratory studies on small-size samples have revealed that the liquefaction potential of sand deposits can be significantly reduced by the reinforced earth technique. About 150 tests were performed on 38-mm diameter samples with woven geotextile, nonwoven geotextile, and coir as reinforcement to study the liquefaction behavior of reinforced soil. This paper evaluates the liquefaction potential of reinforced sand under triaxial stress conditions. A simple analytical method for soil liquefaction based on the cyclic triaxial tests conducted on reinforced sand is presented. The restraining effect of the reinforcement is accounted for as an additional confining stress. Good agreement between the analytical and experimental values is noticed. The results show that the bending stiffness and compressibility of the reinforcement played a dominant role in the shear mobilization along the soil fabric interface. The writers also performed tests on larger-diameter samples and the results revealed that the size effect is marginal, with the results falling on the conservative side.

Laboratory soil-column experiments were conducted to study the distribution of preferential flow paths resulting from removal of colloidal-size clay particles. Flow paths were assumed to result when the fluid energy was able to overcome the cementitious bonding of particles along the pore walls. These experiments specifically studied the influence of clay (kaolinite) percentage in sand-clay mixtures and the effect of hydraulic gradients on pore evolution. Analysis of the effluent during the experiments indicated that clay particles were removed from the soil column, accompanied by an increase in porosity and hydraulic conductivity. Dye experiments were conducted on the same columns to stain the pathways where colloidal particle removal occurred. It was observed that pore distribution was fairly uniform in some cases, while other cases showed distinct preferential flow-path formation. Using concepts of image analysis, the dye pattern was converted to a binary file and analyzed as a spatial random process to characterize the spatial distribution of flow paths. The expected spatial density (λ) and the correlation length were chosen as the key parameters to quantify the random dye patterns and to describe the nature of flow-path evolution. A physically based model was used to identify a dimensionless parameter, G , which expresses the ratio of detachment and deposition forces at any space-time location. Soil detachability was identified as the other key parameter. This expresses the ease with which colloids can be removed from the pore walls. It was observed that λ exhibited an identifiable trend with G , while I was predominantly dependent on detachability of the mixture.

An analysis of pile axial and lateral response to transient dynamic loading is presented allowing for nonlinear soil behavior, the discontinuity conditions at the pile-soil interface, and energy dissipation through radiation damping and soil hysteresis. In addition, the effect of neighboring piles is taken into account for piles in a group. This analysis is used to derive the stiffness of foundation piles of fixed offshore towers. The effect of foundation nonlinearity and pile-soil-pile interaction on the dynamic characteristics of the tower is investigated. It was found that the tower's dynamic characteristics are greatly influenced by the foundation nonlinearity and the pile-soil-pile interaction.