Influences and Prediction of Compaction Degree and Dry-wet Cycles on the Water Holding Properties of Low Liquid Limit Clay

This article aims to study the changes in strength and water holding capacity of low liquid limit clay under different compaction degrees and dry-wet cycles. Based on the variation law of embankment fill compaction in service, soil samples of typical low liquid limit clay in southern Anhui, China, were reshaped with 85%, 90%, and 95% compaction degrees, followed by 0–5 dry wet cycle tests. Then, direct shear tests and soil water characteristic curve (SWCC) tests by filter paper method were conducted on cycled samples, and the suction stress of these samples was calculated backwards. A new SWCC model considering compaction and dry-wet cycles was established. The results show that the shear strength decreases with the increasing dry-wet cycles, and the first cycle has the maximal impact on the shear strength and cohesion of the low liquid limit clay. After 5 dry-wet cycles, the cohesive force and internal friction angle of the 95% compacted soil sample are 2.61 times and 1.24 times that of the 85% compacted soil sample, respectively. When the compaction degree increases, the intake value, suction stress range, and water holding capacity of the soil show an increasing trend. The suction stress of soil samples elevates with the increase of dry-wet cycles in the low effective saturation stage and drops with the rising dry-wet cycles in the high effective saturation stage. The turning point of saturation is between 0.1 and 0.3.