Experimental study on comparison of consolidation creep characteristics between silty sand and silty soil

In order to explain the lagging settlement in the surrounding ground induced by pre-dewatering of excavations, one-dimensional consolidation creep tests are conducted on typical silty sand and silty soil at a metro station site of Jiangsu Province. Based on the experimental results, the compression index, rebound index and secondary consolidation coefficient of the soil are obtained, and the empirical relationships between the rebound index and the compression index, as well as the secondary consolidation coefficient and the compression index, are given. The results of the creep tests demonstrate a well-defined linear relationship between the secondary consolidation coefficient and the consolidation load for both the silty sand and the silty soil, leading to the development of an empirical formula correlating the secondary consolidation coefficient with consolidation pressure. Furthermore, the increase in the secondary consolidation coefficient with rising consolidation pressure is explained from the perspective of the natural structural breakdown of the sandy soil under consolidation pressure. These findings provide valuable experimental evidence for understanding the lagging effects of ground settlement around the excavations induced by pre-dewatering and for the rational estimation of ground settlement.