STUDY ON THE CHARACTERISTICS OF DEFORMATION AND STRENGTH OF A DEEP CLAY UNDER TRIAXIAL HIGH PRESSURE UNLOADING TEST

Taking the clay buried nearly 430-600 meters deep in Juye mine area of Shandong province as an example, the authors analyze the general physical and mechanical parameters of soil. Considering the in-situ stress level of the deep soil at such a depth and its unloading change during the excavation proceeding of the vertical shaft building in the coal mine area, a triaxial servo controlled system is used to carry out the triaxial high pressure unloading tests. The axial stress is kept constant while gradually unloading the confining pressure from 11 MPa, 12 MPa and 14 MPa isotropic stress state is proceeded. The deformation and strength of the deep clay under triaxial high pressure unloading test are then analyzed to obtain related mechanical parameters. The results enriches the studying of soil mechanical properties under high pressure unloading conditions, and provides the basic engineering geological parameters for the building of the vertical shafts in Juye coal mine area.