The outdoor exposure performance of 14 geotextiles is studied to obtain specific durability data for Hong Kong conditions. Wide‐width tensile tests were carried out to evaluate the loss of strength and increase in brittleness of the selected geotextiles. The results show some interesting trends in the degradation behavior, with rate of strength loss generally increasing with radiation intensity. Type of polymer and geotextile construction have some influence, but for short periods of exposure, the difference in behavior between geotextiles is small considering the variability of the geotextile materials. The long‐term performance of geotextiles varies. Non‐UV‐stabilized polypropylene geotextiles are the least durable. For needle‐punched geotextiles, UV‐stabilized‐polypropylene fabrics perform in a similar manner to polyester fabrics. Needle‐punched geotextiles ($\ge 1.45\mathrm{mm}$ thick) are found to be more durable than the thinner woven geotextiles, irrespective of polymer type. For polypropylene geotextiles, needle‐punched fabrics also perform better than the thinner heat‐bonded geotextiles. Recommendations are given on specification requirements for protecting the geotextiles against UV attack during construction. Designers are advised to take into account the possible duration of exposure in designs involving large areas of geotextiles.

The dynamic soil‐reaction characteristics of axially loaded single piles are studied numerically to find simple and rational numerical models for beam‐on‐Winkler foundation‐type analyses of axially loaded single piles. The proposed dynamic $t‐z$ and $Q‐z$ models are shown to yield reliable pile responses for a variety of soil‐pile and loading conditions. One of the convenient features of the models is that they can be easily incorporated into both frequency‐ and time‐domain analyses. Therefore, the proposed models can be extended to problems with nonlinear soil‐pile interaction effects, even though the models are based purely on linearly elastic soil‐pile conditions. The proposed models may be utilized in a variety of problems. For static applications, the models can be used to improve the reliability of existing static $t‐z$ and $Q‐z$ relations at small pile settlements. For dynamic problems, the models can be used to predict the axial responses of dynamically loaded pile foundations.

This paper presents a detailed investigation of the influence of key mechanical and geometrical parameters on the dynamic horizontal stiffness of rigid strip foundations embedded in layered soil. Geometrical parameters include the depth of embedment, the thickness of the top soil layer, and the height of contact of foundation sidewalls with surrounding backfill soil. The influence of the relative shear wave velocities of the layers for a two‐layered soil profile is also investigated. The results are presented in the form of simple, versatile dimensionless graphs. The investigation was conducted using a rigorous algorithm of the boundary element method incorporating isoparametric boundary elements. Higher‐order quadratic elements were used because they can model accurately the wavy nature of the dynamic problem.

Compacted‐stone or ‐sand columns have been used increasingly during the past two decades as a technique to reinforce soft cohesive soils and increase bearing capacity, accelerate consolidation, and improve the settlement response of the foundation soil. The bearing capacity of the granular column is governed mainly by the lateral confining pressure mobilized in the native soft soil to restrain bulging collapse of the granular column. Therefore, the technique becomes unfeasible in soft, compressible clayey soils (i.e., undrained shear strength less than 15 kPa) that do not provide sufficient lateral confinement. This paper presents the main results of an experimental study of the feasibility of using artificially cemented, compacted‐sand columns in the reinforcement of soft cohesive soils. Triaxial compression tests are conducted on composite‐reinforced soil samples made of annular, normally consolidated, kaolinite, reinforced by both cemented and untreated columns of river sand. The test results provide a preliminary data base for a fundamental understanding of the cementation effect on the performance of the granular column, and for a quantitative evaluation of the group effect on the settlement response of the reinforced soil.

The effect of the spatial variability of soil parameters on the calculated settlement and stresses is analyzed. The soil is taken as an elastic solid with random shear modulus and a constant Poisson's ratio. A wave‐number domain approach is proposed for the approximate solution of an elasticity problem in which the shear modulus is a random function of position. This method is based on the spectral representation of the shear modulus. The fluctuated parts of displacement and stresses are first expressed in terms of evolutionary spectra. Then, the second‐order moments of the displacement and stresses are obtained by numerical integration without the use of Monte Carlo simulation. This procedure is applied to a semi‐infinite plane strain problem with vertical variability. Results of the method are presented and compared with Monte Carlo simulation and the “stochastic integral formulation.” For large autocorrelation distance, a random variable model could be sufficient for the analysis of the variability of stresses. However, for small autocorrelation distance, the coefficient of variation of the stresses can become very large; consequently, estimation of stresses by the classical theory of elasticity could be far from reality.

Excess pore pressures measured during cone penetration are often correlated with the characteristics and stress history of fine-grained soil deposits. Recent research with sands in calibration chambers shows that the horizontal effective stress is a major factor controlling soil response to penetration of full displacement probes. Using the distribution of excess pore pressure around a penetrating cone, a pore pressure difference parameter, normalized with the effective vertical stress, is defined and a correlation with $K_0$ is suggested. The interdependence of the suggested parameter (PPSV) and $K_0$ is evaluated using published field data from 15 sites. The normalized pore pressure gradient around the cone appears to be linearly related to $K_0$ although a global relationship is precluded by the scatter in the data. The results, however, appear promising and suggest that large strain parameters can be correlated to the in situ stress in the ground.

A case study is presented herein whereby a heavy vibratory roller was used to densify a 6-ft-(1.8-m) thick layer of gravelly sand fill located below ground-water level. Geotechnical engineering evaluations had concluded that the fill was susceptible to liquefaction during the design seismic event. Excavation and subsequent placement of the same fill in thin compacted lifts would have required a difficult and expensive dewatering effort. The layer was densified by repeated coverages of a heavy vibratory roller. Test borings with continuous standard penetration tests were performed to verify that the intended densification had been achieved.