A Study on Lateral Dashpots for Soil-Structure Interaction and its Application to a Simplified Technique

Abstract

The dynamic characteristics of embedded rigid foundations are studied using the boundary element method. Lateral dashpots are introduced to the soil in plane strain in order to represent the wave propagation toward the third direction from a slice of the soil and their effects are examined. The impedance functions and foundation input motions are presented for the case of a rigid foundation embedded in a half-space or a stratum and for the case of two rigid foundations also embedded in a half-space. The effect of the lateral dashpots on the soil-structure interaction is studied where the embedment, the bedrock and the adjacent foundation are considered. The numerical examples are provided by comparing the results obtained by two-dimensional, approximate three-dimensional and exact three-dimensional analyses. The efficiency of the dashpots is confirmed, in particular, for a foundation embedded in a half-space. Based on this result, the lateral dashpots are introduced to onedimensional soil columns which represent a half-space around an embedded foundation. From this assumption, the impedance functions are easily obtained in an explicit form and the foundation input motions are evaluated using the substructure technique. The validity of this simplified technique is confirmed by comparing its results with those obtained by a three-dimensional boundary element analysis.