Experimental study on triaxial mechanics and permeability characteristics of sandstone on the roof of the closed Sanhejian Coal Mine
Considering the stability and closure of the underground space in the closed Sanhejian Coal Mine,triaxial servo permeability tests and acoustic emission monitoring were conducted on the sandstone samples from its roof.With the obtained test and monitoring results,the variations of stress,strain,acoustic emission,and permeability of samples under different confining pressures were studied,and how permeability was correlated with stress-strain and acoustic emission were analyzed.Based on charac-teristic stress identification,the rock fracture types and final failure modes during deformation were ex-plored.The following beneficial results were obtained.As the confining pressure increases,the peak strength,failure strain,elastic modulus,and residual strength rise gradually.When the confining pressure changes from 5 MPa to 15 MPa,these four parameters rise by 68.17％,49.18％,17.26％,and 60.13％,respectively.The void permeability and the maximum permeability decrease progressively during failure,but their order of magnitude remains unchanged.The proportion of shear cracks grows gradually during failure,and the failure mode changes from unilateral shear failure to bilateral shear fail-ure.The changes of permeability with strain can be divided into four stages,i.e.,slight decrease,basi-cally stable,slow increase,and rapid increase,and the order of magnitude starts to change after the slow increase stage.The crack volume method and the permeability value method can effectively identify the characteristic stress of samples,while the acoustic emission method fails to effectively identify the closure stress and initiation stress as it is greatly affected by seepage.
万方数据
维普
