SWCCs of Silt in Yudong Zone and its Prediction Under Different Drying–Wetting Cycle Conditions

Abstract

Soil–water characteristic curves (SWCCs) play a key role in unsaturated soil mechanics. A series of SWCC tests on Yudong silt with different compaction degrees and drying–wetting cycles were conducted using a GCTS pressure plate apparatus. The test results showed that the SWCCs exhibited hysteresis during the drying–wetting cycles and were affected by the compaction degree. The hysteresis area decreased with increasing drying–wetting cycles. The hysteresis area was obviously affected by the first cycle. The second and third cycles had less obvious effects compared with the first one, but their effects could still be seen. The SWCC’s parameters of Van Genuchten model were obtained by using a Lsqacurve fit function. On basis of the relationships among the fitting parameters, compaction degree, and drying–wetting cycles, a practical and novel approach was proposed to predict SWCCs for Yudong silt under different compaction degrees and drying–wetting cycles. The microstructure changes associated with variations in dry density or compaction degree have been photographed by the scanning electron microscopy (SEM). The SEM results show that the increase in dry density or compaction degree would change the macropore and surface roughness of aggregates, which will produce greater interaction among aggregates, and thus increases the air-entry value.