Densification of granular soil during vibration was investigated using laboratory experiments. Longitudinal vibration was applied to cylindrical columns of sand. The apparatus simplified the boundary conditions of the specimen from those acting on specimens of soil in rigid molds, previously used to investigate vibration effects on granular soil. An analytical model was derived to help interpret laboratory test results. The maximum acceleration, stress, and strain all occurred at the resonant frequency for low base accelerations. As the base acceleration increased in magnitude, the specimen experienced large permanent strains at low frequencies instead of at the resonant frequency where the acceleration of the top cap and the stress were greatest. The analytical model revealed that strain was related only to the elastic component of stress, and that for increased viscous damping, the combined stress (elastic plus viscous) was not greatest at the same frequency as the strain. Knowledge of the stress states alone is not enough to predict permanent strains during vibration. Knowledge of the dynamic strains or the soil damping would be required.

An analytical model is derived to provide solutions for longitudinal vibration of soil columns. The model uses a Kelvin‐Voigt element in which the dynamic stresses are the sum of viscous and elastic components. Damping is represented by a viscous damping coefficient that is independent of frequency. This process produces a frequency‐dependent viscous component of stress. A two‐element solution is derived to allow modeling of nonhomogeneous columns. The soil column has a rigid cap at the top, and vertical accelerations at varying frequencies can be applied to the column base. Dynamic response is measured in terms of acceleration of the top cap, and stresses and strains within the column. Element properties can be varied to approximate nonlinear soil behavior. The tendency for failure to occur increases as the constant‐acceleration frequency approaches zero. Dynamic strain and elastic stress reach a maximum near zero frequency, not at the resonant frequency where maximum dynamic stress and particle acceleration occur.

The Gateway Bridge in Brisbane, Australia, is a major structure by world standards. It crosses the Brisbane River to form a link in easterly bypass of the city of Brisbane. The total length of the structure is 1,627 m, comprising approach spans of precast two‐cell prestressed concrete box girders, and a single‐cell prestressed concrete cast‐in‐place box girder central span and cantilevers. The 260‐m long central span is the longest of its type in the world. Considerable and varied geotechnical input was required for the design and construction of the bridge. The foundation conditions encountered varied locally and were highly variable along the length of the project. Foundation design changes were necessary during the course of construction and quite different foundation systems were employed along the length of the structure. These ranged from shallow pad footings on rock to deep‐rock socketed piles. Approach embankment settlement problems were also encountered. Of most significance was the design of the rock socketed piles, used for the first time in the Brisbane area.

Theoretical models and experimental data for buried tube buckling are reviewed, and linear buckling solutions based on the elastic continuum model for the ground are selected as being most suitable for the design of buried flexible metal tubes. An examination of both theory and experiment confirms that maximum rather than average hoop thrust should be used to characterize the loads in the buried structure. Various scalar correction factors are recommended for use in calibrating the preferred buckling theory so that it can be used in the design of buried flexible tubes.

Groups of laterally loaded piles can be analyzed for displacement and distribution of loads among the piles heads by means of a stiffness matrix equation that incorporates individual pile stiffnesses and the influences of piles on their neighbors using pile‐head interaction factors. To date, only analytically derived interaction factors were available for laterally loaded pile groups; however, in the study reported herein lateral interaction factors for groups of free‐ or pinned‐headed piles were determined from full‐scale experiments in submerged sand. The measured factors tended, on the average, to validate factors that had been derived analytically by others. However, interaction between any two piles was found to be strongly dependent on the relative position of the piles to an extent that reciprocity could not be inferred. The interaction factors also increased with increasing magnitude of load and decreased with increasing numbers of cycles of load.

The Distinct Element Method (DEM), a numerical technique which treats soil as a discrete assemblage of particles, can be useful when local yield, bifurcation behavior or nonlinear soil‐structure interaction occurs. A two‐dimensional disk‐based implementation of the DEM is validated using numerical simulations of standard geotechnical laboratory tests, such as one‐dimensional compression, direct simple shear and triaxial tests. These test results indicate that the two‐dimensional DEM can simulate realistic nonlinear, stress history‐dependent soil behavior appropriately when individual particle rotation is inhibited.

Modeling of large‐scale problems is accomplished by constructing a reduced‐scale model, then applying the geotechnical centrifuge scaling relationships in order to reduce the number of particles simulated and to ensure stress‐strain‐strength similitude between the model and prototype. Full‐scale simulations, including bearing capacity and lateral earth pressure tests, indicate that the DEM can accurately simulate real geotechnical problems, including those possessing large local yield zones.

A laboratory investigation of crushed rock filters is made to evaluate the filter criteria needed for the sandy clays and silts of tropical residual soils. The ability of a downstream filter to seal a concentrated leak through a dam core is assessed. Behavior of the broad, graded, sandy, impervious soils are dominated by the fines fraction. The filter criteria is well represented by $D_{15}$ of filters and $d_{85}^{*}$ of base soils. The derived criteria, $D_{15}/d_{85}^{*}⩽12$ is conservative for judging the acceptability of crushed rock filters as protective filters. The filtering ability of graded filters is sensitive to the grading below the 15% size. The effects of remolding and saturation on the soil properties deserve consideration in the design of filters for the tropical residual soils. The Atterberg Limits of the soils have no significant influence on the needed protective filter.

It is shown theoretically that the arch describing the minor principal stress in the soil behind a retaining wall can be approximated by a catenary which is very close to circular in the range of interest.