Study of the repeated collapsibility of undisturbed loess in Guyuan, China

摘要

At present, the international evaluation method of loess collapsibility only evaluates loess once collapses, but some scholars have found that loess is characterized with the phenomenon of repeated collapsibility under certain conditions. To explore the characteristics of repeated collapsibility of loess and to find a simple and feasible method for evaluating repeated collapsibility of loess, this paper selects soil samples with different water content for repeated compression tests. Loess is a typical structural soil, and its structure is significantly weakened by water and pressure. This paper combines three main parameters influencing the structure of loess to define a comprehensive physical index and explores the relationship between the comprehensive physical index and the structural yield strength of loess under repeated collapsibility. Using the structural yield strength of loess to normalize the compression curve during repeated collapse, a method for evaluating repeated collapsing of loess has been proposed. This method combines the compression index of loess with the basic physical parameters of loess, which is more suitable for evaluating the repeated collapsibility of loess. By comparing the calculation results with the measured results, it was determined that this method has high accuracy. This method was used to calculate the coefficient of collapsibility of Guyuan loess, and the results show that loess with a moisture content of 17% can collapse twice.