非贯通节理岩体直剪试验研究进展

Advances in research of rock masses containing discontinuous joints in direct shear test

基于典型的直剪试验,国内外学者提出了非贯通节理岩体贯通破坏机理,并建立了相应的强度准则,如Jennings方法,即加权平均强度理论和强度准则、Lajtai岩桥破坏理论和强度准则、断裂力学的II型破坏理论和强度准则,拉剪复合破坏和强度准则。然而,非贯通节理岩体破坏机理目前还没有完全弄清楚,已建立的强度准则所包含的重要参数还需深入研究,如:如节理面的传压系数、传剪系数、弱化了的岩桥内摩擦力和内摩擦角等;非贯通节理岩体节理闭合和剪切的本构关系有待建立;不共面非贯通节理岩体全过程最大抗剪强度需进一步研究。伺服直剪试验机、静态应变测试仪、声发射仪、X射线测量等无损检测技术能够为进一步研究非贯通节理岩体的破坏机理,提出新的理论和建立新的强度准则提供强有力的技术支持。

Direct shear test is an effective approach for studying rock masses containing discontinuous joints; through the test, both failure models of joints and of rock bridge, when one of the principal stresses is tensile, can be simulated. Based on this test, failure mechanism has been widely researched; and shear strength criteria have been put forward, such as Jennings method, Lajtai rock theory, shear theory in fracture mechanics, combined failure theory of tensile and shear. However, the failure mechanism is not fully clear, and some parameters in shear strength criteria, for examples, compression transferring coefficient and shear transferring coefficient of rock joints, fundamental shear strength and angle of internal friction of rock bridges, etc. are still uncertain. Closing constitutive relation and shearing constitutive relation of rock masses containing coplanar discontinuous joints, as well as maximum failure strength of rock masses containing noncoplanar discontinuous joints need deeper research. Direct shear testing machine with servo system, static strain tester, acoustic emission technique, nondestructive testing technique, etc. will be greatly helpful to further research on rock masses containing discontinuous joints.