Effect and Modeling of Wetting-Loading-Heating on Water Retention Capacity of Silty Clay

The water-retention capacity of unsaturated soils is usually reflected by the variation law of soil-water characteristic curve. The important effects of load and temperature on soil-water characteristic curves have been gradually recognized, but the studies considering the combined action of wetting-loading-heating on soil-water characteristic curves are seldom reported, and the analysis of dominant influencing factors is rarer. In order to investigate the water holding capacity of silty clay under combined actions, the dry-wet cycling experiments of silty clay under different vertical stress and temperature conditions were carried out, and the influencing mechanism, characteristics and importance of each factor were analyzed. A prediction model reflecting the combined action of multiple factors was then established. The results show that: 1) With the increase of vertical stress, the air intake value of unsaturated soil increases, the moisture reduction rate decreases, and the hysteresis effect of the wet-dry cycle becomes stronger, which occurs at different temperatures; 2) Compared with the experimental curves under the same vertical stress and different temperatures, it is found that the air intake value of soil is slightly lower at higher temperatures; 3) Vertical stress has the greatest influence on water-retention capacity of soil, but it is confined to the low suction stage; the function of dry-wet cycle ranks second and decays rapidly with the number of cycles increasing; the influence of temperature is small and negligible when suction or density is high; 4) The improved L model based on Logistic curve is more suitable for fitting the soil-water characteristic curve of Badong silty clay than V-G model. In summary, the change of internal pore structure is the main cause of characteristic value change caused by vertical stress, which leads to the difference of water-retention performance; temperature mainly affects the water-retention capacity of soil mass in low stress and low suction stage; the influence of three storage conditions on soil-water capacity of silty clay is ordered as vertical stress>dry-wet cycle>temperature distribution; the modified L model can effectively reflect the evolution characteristics of water-retention capacity of silty clay under combined action of wetting-loading-heating. Copyright ©2021 Advanced Engineering Sciences. All rights reserved.