多节理岩体裂纹扩展及变形破坏试验研究

Experimental study of crack propagation and deformation failure of multiple-jointed rock mass

为了研究不同倾角下多节理岩体力学行为,采用10 MN微机控制电液伺服大型多功能动静力三轴仪,开展包含较多预制非贯通节理类岩石试件的单轴压缩试验,研究了多节理岩体裂纹的特征、贯通模式、破坏模式、应力-应变特征等与节理倾角之间的关系。试验结果表明,(1)多节理岩体的裂纹类型主要有翼裂纹和次生共面裂纹,翼裂纹的扩展路径与单个节理情况下的扩展路径差异较大,翼裂纹起裂后沿起裂方向存在较长的扩展长度,直接与相邻节理或翼裂纹形成贯通,并且裂纹的贯通表现出四种不同的模式;(2)多节理岩体的破坏模式归纳为3种类型:平面破坏、块体转动式破坏和台阶式破坏;(3)根据多节理岩体的应力-应变曲线在应变软化阶段所表现出的不同非线性变形行为特征,可以将曲线归纳为4种类型;(4)多节理岩体的强度和变形各向异性特征非常显著,强度和弹性模量均在节理倾角30°时最小,90°时最大。

The uniaxial compression experiments of rock-like specimens with multiple intermittent joints are conducted by 10 MN microcomputer-controlled electro-hydraulic servo large multi-function action force triaxial apparatus to further research mechanical behaviors of multiple-jointed rock mass with different joint dip angles. Researches on the relationship of crack characteristics, coalescence patterns, failure modes, stress-strain characteristics of multiple-jointed rock mass with joint dip angle were performed. The results show that:(1) Crack types of multiple-jointed rock mass mainly include wing crack and second coplanar crack. The propagating path of wing crack is different than that in condition of single joint. Wing cracks propagated a longer distance in the initial direction and directly coalesce with neighbouring joint or wing crack. Four patterns of crack coalescence are found(2) Three failure modes are found on specimens containing multiple joints, i.e. failure through a plane, rotation of new blocks failure and stepped failure.(3) The stress-strain curves of multiple-jointed rock mass at the strain softening stage show different characteristics of nonlinear deformation behaviors and according to that the curves are divided into four types.(4) The anisotropy of strength and deformation of multiple-jointed rock mass is highly obvious. The values of both strength and elastic modulus are maximum at joint dip angle of 90° and minimum at joint dip angle of 30°.