Study On Soil-water Characteristic Curve Of Unsaturated Soil Considering Dynamic Capillary Effect

The occurrence of landslide accidents will adversely affect personal safety,daily life and social economy.The occurrence of landslide is closely related to the unsaturated soil.This paper mainly studies the dynamic soil water characteristic curve of unsaturated soil.At present,most researches use the saturation change rate,to describe the dynamic effect,which cannot reflect the essential reasons of dynamic effect.In this paper,a soil-water characteristic curve model that distinguishes capillary and adsorption is established,and then a dynamic soil-water characteristic curve model under dynamic capillary action is established,and the influence of dynamic effects on suction stress is also analyzed.The main research work is as follows:(1)The soil-water characteristic curve model which can distinguish the adsorption and capillary effect are developed.A nonlinear equation is used to describe the adsorption effect.Overestimation of capillary water in unsaturated soil is then avoided.Through the understanding of the physical characteristics of adsorption in the high suction area,and the parameters of the existing model are modified to establish soils with only adsorption and capillary action.The soil-water characteristic curve model can better predict the rationality of the test data and verify the model.(2)A dynamic soil-water characteristic curve model considering capillary effect is established.Based on the dynamic water content model,the relationship between dynamic suction and capillary water change rate is given.The model can well describe the change of soil water characteristic curve caused by dynamic capillary.Compared with the existing soil water characteristic curve,the model has two addition parameters,which are relate to dynamic effect and capillary effect.The model is then used to simulate existing test data.The results show that the model can better predict the change of dynamic soil water characteristic curve.(3)Based on the dynamic soil-water characteristic curves,the suction stress characteristic curve include dynamic effect is proposed.Test results found in literature are used to validate the model.It is found that the dynamic effect is significant in the suction stress characteristic curve.Therefore,it is necessary to consider the dynamic effect in practical engineering.