During 1977–1978 a series of 25 ft wide (8 m) by 30 ft deep (9 m) sewer culverts were built in the Islais Creek Basin near San Francisco Bay. The sheetpile wall supported excavations for the culverts were made through rubble fill into a soft clay whose depth and strength varied along the culvert alinement. In the area of the thickest clay deposit, the soil was the weakest, apparently because the consolidation pressures were very low. There were a number of possible reasons for this situation, the most likely being the presence of artesian pressures. In the weakest clay, where basal heave factors of safety of the excavation were at or possibly below one, measured lateral movements during excavation were large, in sharp contrast to the smaller movements in adjacent areas where the clay was slightly stronger. One near failure occurred in the weak clay when a problem with the structural system developed. In general, the measured movements, strut loads and pore pressures are consistent with data from other projects when relative basal heave factors of safety are considered.

An inexpensive and realistic procedure is developed for estimating the lateral dynamic stiffness and damping of flexible piles embedded in arbitrarily layered soil deposits. Starting point is the determination of the pile deflection profile for a static force at the top using any reasonable method—beam‐on‐Winkler foundation, finite elements, well‐instrumented pile load tests in the field, etc. Material as well as radiation damping due to waves emanating at different depths from the pile‐soil interface are rationally taken into account; the overall equivalent damping at the top of the pile is then obtained as a function of frequency by means of a suitable energy relationship. The method is applied to study the dynamic behavior of three different piles embedded in two idealized and one actual layered soil deposit; the results of the method, obtained by hand computations, compare favorably with the results of three dimensional dynamic finite element analyses.

This paper reports on the magnitudes and distribution of static at‐rest stresses behind a rigid wall as a function of soil densification and on static active stresses mobilized behind a rigid wall rotating about its base. The experiments were conducted on the retaining wall system which is permanently affixed to the University of Washington shaking table which is described. Based on these experiments on Ottawa sand, the following conclusions are drawn: (1) The stress distribution behind a non‐yielding rigid wall is hydrostatic; (2) the well known Jaky equation applies only when the backfill is deposited at its loosest state; and (3) when the backfill behind the wall is either compacted or vibrated to increase its density, the magnitude of the at‐rest stresses increases due to densification and the total at‐rest stress exerted on the wall will then be the sum of the stresses due to gravity effects and the locked‐in horizontal stresses due to densification. For a rigid wall rotating about the base: (1) The static active stress distribution behind the wall is also hydrostatic; (2) soil densification de creases the magnitudes of active stresses behind such walls; (3) the magnitude of the active stresses behind a wall rotating at its base can be obtained by the classical Coulomb equation; and (4) the state of active stress propagates down ward from the surface of the soil with increasing wall rotation.

A test program using vibroflotation to density silty sands beneath surface day and silt layers is presented. Vibroflotation compaction columns were constructed along the downstream toe of an embankment dam at two locations. At one location, columns were placed through the dam crest. The sands treated contained between 5% and 35% fines. The test program and construction monitoring are described in detail along with the atypical construction procedure used in the program. Comparisons of before and after standard penetration test and cone penetrometer test results generally indicated no improvement after construction. Failure of the method to density the sand is attributed principally to the presence of significant amounts of fines in the sand.

Exact formulas for the calculation of vertical stresses in soil are presented without the use of charts and tables. Formulas are derived using the basic Boussinesq's equation for a point load to calculate the vertical stresses due to a triangular loading on a rectangular area.