Analysis of critical stress level of subgrade red clay under cyclic loading

The shakedown and plastic behaviors of cohesive subgrade soil under cyclic loading are described. Based on the shakedown concept, various mechanical behaviors of subgrade red clay are discussed by repeated loading tests. The tests are performed with various conditions of subgrade soil, including different moisture contents, stress levels, numbers of repeated loadings and stress paths. According to the test results, the factors responsible for various mechanical behaviors of subgrade soil are analyzed in detail. The influence factors of the subgrade red clay mechanical behavior under cyclic loading and its permanent deformation trend as well as the mechanical behavior development rules are also analyzed systemically. The shakedown limit and critical stress level of subgrade red clay under cyclic loading with different moisture contents are presented. The plastic mechanical behavior can be divided into three phases: stable, failure and critical phrases, which are further divided into accepted condition and unaccepted condition. The critical stress level of subgrade red clay under cyclic loading is 41.8 %.