Temperature effect on water retention capacity of Nanning expansive soil and its microscopic mechanism

To explore the variation of water retention capacity of expansive soil at different temperatures, the calibration curves of Whatman No.42 filter paper were measured by vapor equilibrium method at 5, 25, 40 ℃ and 60 ℃, and the bilinear calibration equation considering temperature effect was established. The results show that the water retention capacity of the filter paper decreases with the increase of temperature, and the effect on the high suction section of calibration curve is weaker than the low suction section. On this basis, Nanning expansive soil is taken as the research object, and the soil-water characteristic curves of Nanning expansive soil at different temperatures are measured by filter paper method. It is found that the water retention capacity of Nanning expansive soil decreases with the increase of temperature, but the influence of temperature depends on matric suction, especially when it is above 40 MPa, the water-retention capacity of Nanning expansive soil remains unchanged with temperatures. To probe into the microscopic mechanism of the change of water retention capacity of Nanning expansive soil under temperature, some samples were selected for mercury intrusion porosimetry test and bound water adsorption test. Based on the test results, the microscopic mechanism of water retention capacity change of Nanning expansive soil was analyzed from the physical mechanism of the interaction between each phase and each phase interface.