Dynamic behaviour and damage characteristics of loess in Xianyang, China

Abstract

In engineering practice, the in situ soil layer is under different static pressures and experiences different types of dynamic loads. To determine the influence of stress state and dynamic load type on the dynamic characteristics of, and damage evolution in, saturated loess, consolidated-undrained dynamic triaxial tests were conducted on samples subjected to different confining pressures and consolidation stress ratios. During the test, rectangular wave and sine wave were selected as types of applied dynamic load. Results show that samples with good consolidation effect, and loaded by the sine wave, exhibit relatively high strength. The deformation of the samples is influenced by their initial consolidation state and the value of dynamic stress: the better the consolidation effect of samples and the lower the applied dynamic stress, the smaller the strain difference therein; with the increase of dynamic stress, greater strain occurs in samples loaded by a rectangular wave. The influence of waveforms on the initial dynamic elastic modulus changed with the stress state: this was significantly affected by application of sine wave loading (low confining pressure, low consolidation stress ratio), significantly affected by application of rectangular wave loading (low confining pressure, high consolidation stress ratio), and slightly affected by waveforms (high confining pressure). The instantaneous application of rectangular wave load can cause consolidated samples to be strengthened in the early test stage, while damage developed rapidly with the proceeding of loading process.