Analysis of Laterally Loaded Long or Intermediate Drilled Shafts of Small or Large Diameter in Layered Soil
Strain wedge (SW) model formulation has been used for evaluating the response of a single pile or a group of piles in layered soils to lateral loading. The SW model approach provides appropriate prediction for the behavior of an isolated pile and pile group under lateral static loading in layered soil (sand and/or clay). In this study, the authors extend the capability of the SW model to predict the response of laterally loaded large diameter shafts considering 1) the influence of shaft type on the lateral shaft response; 2) the nonlinear behavior of shaft material and its effect on the soilshaft-interaction; 3) developing partial or complete liquefaction in the surrounding soil profile based on far and near-field induced porewater pressure; and 4) vertical side shear resistance along the shaft wall that has a significant contribution to the lateral shaft response.
Preliminary Test Results for Full Scale Drilled Shaft Under Cyclic Lateral Loading
Preliminary results are presented of a field testing program for a full-scale, large diameter cast-in-drilled-hole (CIDH) shaft/column under cyclic lateral loading. The shaft was extensively instrumented to enable high precision, redundant section curvature measurements, measurements of pressure at the soil-shaft interface around the shaft perimeter, and in situ measurements of concrete quality. The principal objective of the testing was to characterize the soil-shaft interaction across a wide displacement range to gain insight into the adequacy of existing design guidelines (which are based principally on the testing of small diameter piles) for the large diameter shafts commonly used to support highway bridges in California. Also of interest is the failure mechanism of the shaft-column, since most previous tests of large-diameter shaft-columns do not test the column to large levels of ductility. This testing was only recently completed, and reduction and interpretation of the data is ongoing as of this writing. This paper presents preliminary results of the overall specimen performance across the full range of tested displacements. Details of the soil-shaft interaction remain under study, and are not presented here.
The role of dissolved oxygen in supercritical water in the oxidation of ferritic–martensitic steel
Abstract To assess the role of dissolved oxygen in supercritical water on the growth processes of oxide scales, a marker experiment of ferritic–martensitic steel was performed by exposing to supercritical water (H 2 16 O) containing marked 18 O 2 at 600 °C under 25 MPa. The oxide scale was analysed by using Secondary Ion Mass Spectrometry (SIMS). The oxygen isotope profile shows that dissolved oxygen and supercritical water react with metals simultaneously. Dissolved oxygen changes the oxidation/reduction potential of supercritical water leading to an increase in the oxidation rate. The oxidation rate increases with increase in dissolved oxygen content in supercritical water. The mechanism of the effect of dissolved oxygen on oxidation is discussed.