摘要
Rock is exposed to the combined effects of the confining pressure and strain rate during the dynamic excavation process in deeply buried high-stress tunnels.Therefore,a constitutive model that considers both the strain rate and the confining pressure effect plays a crucial role in evaluating the disturbance and stability of deeply buried tunnels.Taking mudstone as an example,a series of tests were performed to reveal the combined effect of the strain rate and confining pressure on the mechanical behavior of soft rock,and a novel statistical damage constitutive model was proposed.The confining pressures of 0 MPa,10 MPa,20 MPa,and 30 MPa and strain rates of 10^(-5)s^(-1),10^(-4)s^(-1),10^(-3)s^(-1),and 10^(-2)s^(-1)were investigated.The results show that the rock strength increases with increasing confining pressure and strain rate,and that the contributions of these two factors can be considered independent of each other.However,an increase in the confining pressure reduces the degree of rock damage and increases the ductility of the sample at failure,whereas the strain rate has the opposite effect.Finally,a full deformation process damage model considering strain rate effect is established based on a modified Hoek‒Brown strength criterion considering the strain rate.The model can capture the nonlinear increase in strength and elastic modulus with increasing confining pressure and strain rate,reproducing the brittle‒ductile transition characteristics and the full deformation process.
基金
financed by the Key Technology R&D Plan of Yunnan Provincial Department of Science and Technology(Grant No.202303AA080003)
the Shanghai Rising-Star Program(Grant No.23QB1404800).
