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随着开采深度的不断加深,开采活动在地下开挖体周边引起的压缩应力可能足以引起岩爆甚至作业人员伤害等灾害.地下开挖体周边岩石处于平面应力或平面压缩状态.为了研究地质材料的双轴强度,对从煤矿井下采出的100 mm立方体灰砂岩试件的双轴力学性能和强度进行了实验研究.双轴压缩的加载速度为1 MPa/s.对砂岩立方体试件和标准试件的单轴强度进行了测试并与双轴试验结果进行比较.实验采用了2种加载路径:一种是保持双向受力相等直至破坏;另一种是保持双向受力相等直至单轴抗压强度的1/2,然后保持约束荷载恒定,增加另一荷载直至破坏.给出了试验结果和所观察到的现象,探讨了砂岩双轴加载的破坏机理.试验结果表明,随着约束荷载的增加,岩石双轴强度显著增加,试件的破坏通常由加载初期开始,并持续地沿自由面片落,最终产生加载平面外的剪切破坏,同时伴随轻微的断裂声响.
With the continuous deepening of mining depth, the compressive stress caused by mining activities around the underground excavation body may be enough to cause the disasters such as rock burst and even operator injury, etc. The rock around the underground excavation body is in plane stress or plane compression state.In order to study the geological materials The biaxial mechanical properties and strength of the 100 mm cube sandstone samples taken from coal mines were investigated.The biaxial compression loading rate was 1 MPa / The uniaxial strength of the specimen was tested and compared with the results of biaxial test.The experiment adopted two kinds of loading paths: one is to keep the bi-directional force equal to the destruction, the other is to keep the bi-directional force equal until the uniaxial resistance The compressive strength is 1/2, then the restraining load is kept constant, and the other load is increased until it is destroyed. The test results and observed phenomena are given and the failure mechanism of the biaxial loading of sandstone is discussed. The experimental results show that with the restraining load , The biaxial strength of the rock increases significantly. The failure of the specimen usually starts from the initial stage of loading and continues to fall along the free surface, eventually resulting in shear failure outside the loading plane. Accompanied by a slight breakage sound.