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通过含一组预置张开裂隙石膏试件的单轴压缩试验,系统地研究了当节理连通率固定时,节理组的间距和倾角对试件强度和变形特性的影响。研究发现:1随着节理间距的增大,试件的应力–应变曲线的由单峰型变为多峰型,延性增大。试验中观察到的应力–应变曲线包括4种类型,单峰型、软化段多峰型、多峰平台后软化型和多峰平台后硬化型。2当节理间距不变时,试件的当量化强度、当量化弹性模量和第一峰值应变随节理倾角的变化曲线都呈V型,其最小值发生在节理倾角为45°处;而残余强度与强度之比和第二峰值应变随节理面倾角的变化规律则反之。3当节理倾角不变时,当量化弹模、当量化强度和第一峰值应变都随节理化系数的增大而减小;而残余强度与强度之比和第二峰值应变则反之。4各节理倾角下,试件的当量化弹模和当量化强度随节理化系数的变化规律可以用相同形式的幂函数来表示。5上述宏观力学行为与预制节理闭合、次生裂隙发展等细观损伤力学机制密切相关。上述研究表明,节理间距对岩体的强度和变形特性的影响有显著的各向异性。
Through the uniaxial compression test with a group of prestressed open gypsum specimens, the effects of the pitch and inclination of the joint group on the strength and deformation properties of the specimens were investigated systematically when the joint connection rate was fixed. The results show that: 1 With the increase of joint spacing, the stress-strain curve of the specimen changes from unimodal to multimodal and the ductility increases. The stress-strain curves observed in the experiment included four types, unimodal, softening multimodal, multimodal platform post softening and multimodal platform post hardening. When the joint spacing is constant, the curves of the equivalent strength, the equivalent elastic modulus and the first peak strain with the inclination of the joint are V-shaped, and the minimum value occurs at the joint inclination of 45 °. The residual The ratio of strength to strength and the second peak strain change with the inclination of the joint plane is the opposite. When the dip angle of the joint is constant, the quantitative elastic modulus, the quantitative intensity and the first peak strain decrease with the increase of the joint coefficient. The ratio of the residual strength to the intensity and the second peak strain are the opposite. 4 Under the inclination of each joint, the equivalent elastic modulus of the specimen and the variation of the equivalent strength with the joint coefficient can be expressed by the same form of power function. 5 The macroscopic mechanical behavior is closely related to mechanics of meso-damage mechanics such as prefabricated joint closure and development of secondary cracks. The above studies show that the effect of joint spacing on the strength and deformation characteristics of rock mass is significantly anisotropic.