Based on the characteristics of stress transfer distribution in surrounding rock during roadway excava-tion,this study focuses on exploring the deformation law of rock mass under non-uniform loading.A new rock mechanics testing method has been proposed,in which rock specimens of the specific trapezoidal cross section were prepared and corresponding rigid pads were fabricated based on the stress-strain curve of rocks to achieve non-uniform distribution of axial loads during uniaxial compression.The relationship between load distribution and the height of cross section during compression of trapezoidal section specimens was calculated,and the stress distribution of specimens under test conditions and rock state zoning were discussed.When the height of the right side is 75 mm,the left side of the specimen was in the plastic deformation stage before failure,while the of height of right side reaches 85 mm,the specimen was still in the elastic deformation stage before failure.From the tests,the deformation characteristics of a single intact rock mass under non-uniform load compression conditions was obtained.Obvious zoneing phenomenon was observed before the failure of trapezoid-sectional sandstone,wher-ethe degree of plastic hardening at each point is inconsistent.The plastic hardening degree reached its maximum at point 3 on the right side of S85 specimen,and it reaches its maximum at point 2 on the right side of S75 speci-men.The results indicate that rocks under non-uniform load compression exhibit nonlinear deformation character-istics,and the local damage accelerated the plastic softening of rocks nearby.It is proposed that under non-uniform loading conditions,the difference in axial strain within different vertical cross sections caused additional shear stress.The induced shear stresses are positively correlated with the rate of strain change,but there directions opposite in the upper and lower directions of the neutral plane.Under the action of additional shear stress,the plane angle of the maximum shear stress of the rock element increased,and the specimen failure mode changed from the original"core"shape to a relatively elongated pyramid shape along the inclined plane.
关键词
岩石力学/非均匀荷载/单轴压缩/CT扫描/变形与破坏
Key words
rock mechanics/non-uniform load/uniaxial compression/CT scanning/deformation and failure
维普
万方数据