Research on influence of air-entry value on capillary hysteresis internal variable model

Soil-water characteristic relationship is a function about the connection between matric suction and water content. The research shows that the air-entry value has great influence on the drying scanning curve when the starting point of the curve is near the highly saturated level. A capillary hysteresis internal variable model (HIVM) put forward by Wei Changfu is able to simulate the hysteresis characteristic of the scanning curve; but the influence of the air-entry value is neglected. There exist some deviations between the simulation of the drying scanning curve and the factual results. Based on the theory of HIVM and the empirical model about the traditional soil-water characteristic relationship, a modified HIVM is put forward. The influence of the air-entry value on the drying scanning curve whose starting point is near the highly saturated level is considered in this new model. While in drying path, the effects of air-entry value on the scanning curves that the original points at the highly saturated range is considered. According to the data from the simulation calculation to the various soil samples, in the modified HIVM, the influence of the air-entry value on the drying scanning curve is considered; so it is better than the original model.