大理岩裂隙岩体流变特性试验研究

Experimental Studies on the Rheological Properties of Marble Rock Mass

该文提出并运用地质作用分析与力学过程模拟、力学参数控制相结合的岩体试件制备与试验技术方法,将取自某大型水电工程深埋引水隧洞围岩的典型大理岩块标准试件制备成含有裂隙的岩体试件,通过单轴压缩蠕变、单轴压缩松弛、单轴压缩卸荷和三轴压缩蠕变试验,揭示了大理岩体的流变特性。试验结果表明:该大理岩体的流变特性可用西原模型来表征,并据此求解了流变参数和长期强度;岩体的强度存在显著时效弱化特征,与瞬时强度参数相比,c_∞降低了60%,φ_∞降低了14%;岩体抗剪强度的时效弱化效应与岩体应力有关,低应力下的强度时效弱化效应比高应力下更为显著。这些成果与方法可供工程与同类研究参考。

This paper puts forward and applies the method of preparation and test of rock specimen combining geomechanical analysis with mechanical process simulation and mechanical param eter control.Typical marble standard specimens acquired from the surrounding rock of the diversion tunnel in a hydropower station were prepared into fractured rock mass replica specimens by simulating the geological-m echanical processes of the rock mass formation.Uniaxial compression c ree p,relaxation and unloading tests as well as ti-axial compression creep tests were performed on the replica specimens to reveal the rheological properties of marble rock mass.According to the test resu lts,the rheological properties can be characterized by the Nishihara model from which the rheological param eters and long-term strength can be calculated.The rock mass strength showed some tim e-dependent weakening characteristics;comparing with the instantaneous strength param eters,c∞decreased by 60%andφ∞decreased by 1 4%.The tim e-d ep en d en t shear strength weakening effect of rock mass was related to the ground stress of the rock m ass,and it was more significant under low ground stress than that under high ground stress.