蟠龙抽水蓄能电站硐室围岩三轴试验及本构模型

Triaxial compression test and constitutive model of surrounding rockof tunnels in Panlong Pumped-Storage Power Station

利用岩石全自动伺服试验仪对重庆蟠龙抽水蓄能电站硐室围岩的砂岩试样开展了不同围压下的常规三轴压缩试验,进而构建了包含统一硬化/软化函数的弹塑性本构模型并进行了验证。试验结果表明,随着围压的增大,由原生缺陷闭合引起的初始非线性变形阶段逐渐减小,试样破坏时的峰值强度随围压增大而增大,由单轴压缩时的84.8 MPa增大到围压10 MPa时的168.5 MPa;峰值强度和围压之间呈现较好的线性关系,黏聚力和内摩擦角分别为15.2 MPa和52°。数值模拟与试验数据的比较表明,提出的弹塑性本构模型能够描述砂岩的主要力学现象,验证了该模型的可靠性。

This paper focus on the mechanical properties of the surrounding rock(sandstone)in the chamber of Chongqing Panlong Pumped-Storage Power Station.Conventional triaxial compression instantaneous tests under different confining pressures were first performed using a servo-controlled triaxial testing machine for rocks,based on which a macroscopic elastoplastic constitutive model was developed and validated.The testing results show that with the increase of confining pressure,the compaction stage caused by the progressive closure of initial voids and microcracks becomes less and less obvious,and the nonlinearity disappears gradually.In addition,the peak strengths of rock specimen increase with the confining pressure,ranging from 84.8 MPa under uniaxial compression to 168.5 MPa under the confining pressure of 10 MPa.There presents a satisfactory linear relationship between peak strengths and confining pressures,from which we derive the material cohesion 15.2 MPa and the friction angle 52 degrees.Numerical results show that the proposed model containing a unified hardening/softening function can describe quite well the fundamental mechanical behaviors of the investigated sandstone,which demonstrates the feasibility of the proposed constitutive model.