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针对节理岩体开挖卸荷所产生的各向异性力学难题,通过制作不同倾角单一预制节理试件,开展节理岩体三轴卸荷试验,研究卸荷条件下节理岩体的应力–应变关系、变形特征、强度特征和破坏模式。得到如下结论:(1)进入卸荷阶段之后,0°,30°和90°倾角节理试件的应力–应变曲线依次出现屈服、软化和残余变形阶段,而45°和60°倾角节理试件只出现屈服阶段。(2)节理试件的变形模量随节理倾角呈U型变化,其中,60°倾角节理试件的变形模量最小;随着围压升高,不同倾角节理试件之间的变形特性差异逐渐减小。(3)0°,30°和90°倾角节理试件的抗压强度降低,而45°和60°倾角节理试件几乎未降低;节理试件的黏聚力随节理倾角呈U型变化,其中,60°倾角节理试件仍为最小;而内摩擦角随节理倾角增大而增大。(4)0°,30°和90°倾角节理试件的破坏模式均为穿越节理的压剪破坏,且不受节理影响,而45°和60°倾角节理试件的破坏模式均为沿节理面滑动破坏。(5)揭示节理岩体的卸荷力学特性分为受岩块强度控制和节理面强度控制。
Aiming at the anisotropy mechanics problem caused by rock excavation and unloading of jointed rock mass, the uniaxial unloading test of jointed rock mass is carried out by making a single prefabricated joint specimen with different inclination angle to study the stress-strain relationship of jointed rock mass under unloading condition , Deformation features, strength features and destruction patterns. The conclusions are as follows: (1) After entering the unloading stage, the stress-strain curves of the joints at 0 °, 30 ° and 90 ° dip in order of yielding, softening and residual deformation, while the 45 ° and 60 ° joints Only yield stage. (2) The deformation modulus of joint specimen changes U-shaped with the inclination of joint, among them, the deformation modulus of joint specimen with 60 ° inclination is the smallest. With the increase of confining pressure, the deformation characteristics of specimens with different inclination angles are different slowing shrieking. (3) The compressive strength of specimens with 0 °, 30 ° and 90 ° inclination decreases, while the specimens with 45 ° and 60 ° inclination have almost no reduction. The cohesion of joint specimen changes U-shape with the inclination of joint, Among them, the specimens with 60 ° inclination joints are still the smallest, while the internal friction angles increase with the inclination of joints. (4) The failure modes of the specimens with 0 °, 30 ° and 90 ° inclination joints are all the compression-shear failures that cross the joints and are not affected by the joints. However, the failure modes of 45 ° and 60 ° joints are along the joint Surface sliding damage. (5) It is revealed that unloading mechanical properties of jointed rock mass are divided into rock block strength control and joint surface strength control.