巴基斯坦盐岩直剪试验研究

Direct Shear Tests on A Pakistan Rock Salt

采用YZW100型直剪试验机对巴基斯坦高纯度盐岩开展了直剪试验,分析了盐岩的剪切强度、剪切变形与破坏模式。结果表明:盐岩的剪切破坏是一种延性破坏,剪切应力-位移曲线较为平缓,且残余应力较大,摩擦承载能力强;盐岩的抗剪强度和残余强度均随法向力的增加而提高;巴基斯坦盐岩的黏聚力为7.41 MPa,内摩擦角为44.1°,残余黏聚力0.16 MPa,残余内摩擦角47.1°。与国内层状盐岩相比,高纯巴基斯坦盐岩的内摩擦角相近,黏聚力更高,抗剪能力更强。盐岩的剪切破坏断面不光滑,局部具有明显的擦痕,类似于"犁沟效应"。研究结果对深入理解盐岩的破坏机理及地下储气库的稳定性具有参考价值。

Direct shear tests on a high purity Pakistan rock salt samples were performed by using a YZW100 direct shear testing device.The shear strength,shear deformation and failure mode of rock salt samples were analyzed.The results show that the shear failure mode of the salt rock is a ductile failure,and the shear stress-displacement curve is in a gentle change with high residual stress which indicating the strong frictional resistance in the sample tested.Both the shear strength and the residual strength of rock salt samples increase with the increase of normal force applied.The tested cohesion of the Pakistan rock salt samples is 7.41 MP with an internal friction angle of 44.1°while the tested residual cohesion is 0.16 MPa,and the residual internal friction angle is 47.1°.Comparing with domestic stratified rock salt samples,the high purity Pakistani rock salt samples have similar internal friction angle,but higher cohesion and therefore a stronger shear strength.The shear failure plane of rock salt samples is not smooth and there are obvious local scratches observed,which is similar to the"furrow effect".The test results have the reference value for the further understanding the failure mechanism of salt rock as well as the stability of the underground gas storage facilities.