华山花岗岩动力学行为与破坏准则研究

A study of the dynamic behavior and failure criterion of the granite in Huashan

对华山花岗岩进行了应变率范围10-4~100/s、围压范围20~100MPa的动三轴试验测试,结果表明在不同围压下,随着应变率增加,花岗岩的抗压强度增长幅度呈减小趋势,弹性模量和泊松比与应变率没有明确关系;随着围压的增加,弹性模量和泊松比与围压间也没有明确关系。接着,作者分别判别了动态的莫尔-库伦强度准则、动态的霍克-布朗强度准则的适用性,并对试验数据进行分析。研究结果表明,在中等应变率下,动态莫尔-库伦强度准则和动态霍克-布朗强度准则均适用,当采用动态莫尔-库伦强度准则时,花岗岩的内摩擦角随应变率增加变化幅度很小,其抗压强度主要取决于花岗岩的粘聚力;当采用动态霍克-布朗强度准则时,参数m对应变率变化不敏感。

Dynamic triaxial tests for the granite in Huashan are conducted with strain rate ranging from 10- 4to 100/ s and confining pressures from 20 to 100 MPa. The results show that under different confining pressures, with the increase of strain rate,the growth rate of compressive strength of the granite shows a decreasing trend. The elastic modulus and Poisson＇s ratio seem to have no clear relationship with the strain rate. As the confining pressure rises,the strain rate exerts little influence on the elastic modulus and Poisson＇s ratio. By identifying the dynamic Mohr-Coulomb criterion and the dynamic Hoek-Brown criterion respectively,the test results are analyzed. The results indicate that under the moderate strain rates,with the dynamic MohrCoulomb strength criterion used,the internal friction angle changes slightly with the increase of strain rate, and the compressive strength of the granite mainly depends on its cohesion. As for the dynamic Hoek-Brown strength criterion,the parameter m is not sensitive to strain rate.