Lateral Displacement of Ground Caused by Soil–Cement Column Installation

Abstract

Closed form equations for calculating the lateral displacement caused by the installation of soil–cement columns are derived based on cylindrical cavity expansion theory. The radius of the cavity needs to be predetermined empirically, mainly with reference to the amount of admixture injected and injection pressure as well as the stiffness of the surrounding soil. Also, an empirical equation is proposed for considering the partial “plane strain” effect of installing a row of columns. The proposed method has been applied to four reported field tests conducted in Saga, Japan, using the slurry double mixing (SDM) method, the dry jet mixing (DJM) method, and the wet jet mixing (WJM) method. The radius of influence, i.e., where the lateral displacement in the soil is less than 5 mm during the installation of soil–cement columns, is found from the field data to be approximately 30, 40, and 50 m for the SDM, DJM, and WJM, respectively. It is shown that the proposed method yielded a reasonable prediction of these field measurements. The field data also indicate that the installation sequence has a considerable influence on the observed lateral displacement; but the proposed method can only consider two extreme conditions of this influence. It is suggested that the method is a useful tool for the design of soft subsoil improvement resulting from the installation of soil-cement columns.