An experimental study of the influence of stress history on parameters of an aquitard

The water in aquitards is an important part of groundwater resources. It is of important significance to determine hydrogeological parameters of an aquitard for the management and evaluation of groundwater resources and for land subsidence. This paper examined the law of the water flow in the aquitard with laboratory test and discussed the law of depletion and deformation of the aquitard when water is released from the aquitard. The results show that the consolidation of the aquitard lags behind the drawdown change of the adjacent aquifer. The deformation rate of the aquitard becomes smaller and tends to zeros under the condition of a constant drawdown of the adjacent aquifer. Based on the results of the laboratory test, the hydrogeological parameters of the aquitard were calculated by using the type curve method under different stress histories. The results suggest that the coefficient of permeability changes little, the specific storativity changes greatly and the consolidation coefficient of the soil layer becomes larger in the large deformation and small deformation tests. The small deformation test is carried out on the basis of the large deformation test of the soil layer. The stress history of the soil layer has little effect on the coefficient of permeability of the soil layer, but has a great influence on the specific storativity.