关键词:

岩石力学 , 峰后循环荷载 , 孔洞岩石 , 力学特性 , 渗流特性

Abstract: The rock itself is inhomogeneous, and the plastic failure of the aquifuge rock mass within the failure range of the coal seam floor occurs due to coal seam mining. The adjacent roadway excavation and working face mining and other projects lead to the rock mass undergoing cyclic loading and unloading process after failure. In order to investigate the effect of post-peak cyclic loads on the mechanics and permeability of rock masses with axial hole defects, and to clarify the influence of repeated engineering disturbance on water inrush of defective floor rock mass, the following was done. A post-peak cyclic loading test study was carried out on sandstone with holes of 5, 10, 15, and 20 mm under a confining pressure of 20 MPa. This study was based on the rock adaptive multi-field test instrument. The results show that : ( 1 ) In the conventional triaxial compression stage, the permeability of rock increases and decreases with the closure and development of internal cracks in rock. The brittle failure characteristics of rock with 5 mm pore size are obvious, and the rock with 10 mm, 15 mm and 20 mm pore size is intermittent. ( 2 ) In the post-peak cycle stage, the change of rock permeability shows a regular cycle with the action of axial pressure and confining pressure. In the cyclic unloading stage, the rock permeability increases rapidly and decreases rapidly. ( 3 ) Cyclic loading and unloading causes cumulative damage to the rock, and the cyclic bearing capacity of the rock decreases with the increase of the pore size. The total amount of seepage channel expansion of the rock containing pores under post-peak cyclic loading and unloading is greater than the total amount of rock particle accumulation and blockage in the seepage channel. ( 4 ) The failure mode of rock with holes is still transfixion shear failure. The cyclic loading makes the secondary shear cracks develop and the degree of crack development increases with the increase of pore size, and the failure mode of rock tends to be complex.