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岩石峰后力学特性的理论研究对于深部煤炭的安全开采至关重要。开展粉砂岩的峰后振动循环和加卸载试验:首先以0.1 MPa/s的速率将围压增至20 MPa,然后以60 k N/min速率施加轴向荷载直至峰值q,再进行轴向卸载至0,最后轴向施加10~80次的正弦振动荷载。通过总结振动荷载对粉砂岩强度、变形、损伤和弹性模量的作用规律,研究了振动荷载对砂岩峰后损伤变形特性的影响。结果表明:少量的振动荷载有利于粉砂岩变形损伤的闭合,可以提高岩石的弹性模量,使岩石变得相对坚硬;但过多次数的循环荷载会引起岩石的变形进一步发展,产生新的损伤,同时也会使岩石变软。峰后阶段的振动荷载会促进新裂纹的产生、发展和贯通,最终产生多组破裂面。
The theoretical study of the mechanical properties of rock after the peak is crucial to the safe mining of deep coal. The post-peak vibrational cycle and loading-unloading tests were carried out on siltstone: first, the confining pressure was increased to 20 MPa at a rate of 0.1 MPa / s, and then the axial load was applied at a rate of 60 kN / min until the peak q, To 0, the last axial application of 10 to 80 times the sine vibration load. The effect of vibration load on the post-peak damage characteristics of sandstone was studied by summarizing the effect of vibration load on the strength, deformation, damage and elastic modulus of siltstone. The results show that a small amount of vibration load is beneficial to the closure of the deformation damage of the siltstone and the elastic modulus of the rock can be increased and the rock becomes relatively rigid. However, excessive cyclic loading can cause the deformation of the rock to further develop and generate new damage , But also make the rock soft. Vibration loads in the post-peak stage will promote the generation, development and penetration of new cracks and finally produce multiple sets of rupture planes.