Abstract： A series of laboratory direct shear tests were carried out on unloaded coarse sand samples in order to analyze the effects of unloading action, overconsolidation ratio, pre-consolidation pressure and dilatancy on shear strength of coarse sand. The test results show that shear stress under certain shear displacement increases with increasing OCR for the same vertical stress after unloading; peak strength increases with increasing OCR for low overconsolidation ratios, while the effect of OCR on peak strength can be almost neglected for large overconsolidation ratios; peak strength increases linearly with increasing vertical stress when the vertical stress is quite small after unloading, while the vertical stress has little effect on peak strength when it reaches a certain level; compared with normally-consolidated sand specimens, overconsolidated sand specimens exhibit dilatancy to some extent under relatively small vertical stresses after unloading, which is more evident especially for those low vertical stresses, and both frictional and dilatancy strengths contribute to peak strength of the sand with dilatancy. Based on the experimental results, the linearly fitted relationship between peak internal friction angle and maximum dilatancy angle for coarse sand was accordingly obtained.
曹宇春 汪科迪. 卸载对粗砂抗剪强度影响的直剪试验研究[J]. 土木工程学报, 2020, 53(1): 84-91.
Cao Yuchun Wang Kedi. Direct shear test study on the effect of unloading on shear strength of coarse sand. 土木工程学报, 2020, 53(1): 84-91.
