关于层状岩体抗拉强度测定方法的讨论

Discussion on Methods of Tensile Strength Determination of Layered Rock Mass

为了探究层状岩体抗拉强度合适的测定方法,将前人对巴西圆盘劈裂的理论和试验成果进行了归纳总结;并在此基础上,对直接拉伸法进行理论分析,提出了合理的建议。研究表明:巴西圆盘劈裂试验对试样的要求是在加载直径线两侧的层理构造和岩石材料均对称分布,只有这样,圆盘试样在线性荷载作用下,内部应力才能对称分布,劈裂破坏面才会沿着加载直径方向穿过圆盘中心点,从而巴西劈裂的理论计算公式才能得到满足;在直接拉伸试验中,试样的破坏形态和机理有三种沿层理面的张拉破坏、沿层理面的剪切破坏、基质的张拉破坏,且抗拉强度均为σt=F/A;巴西圆盘劈裂试验的适用范围不能盲目地扩大,对于层状岩体的抗拉强度测定方法,建议选用直接拉伸法。

In order to explore the suitable method of measuring the tensile strength of layered rock mass,the theory and test results of Brazilian disk splitting were summarized.The theoretical analysis of direct tensile method was then proposed reasonable advice.The results are as follows：Brazil test requirements of the sample is that both sides of the loading diameter stratification structure and rock materials are symmetrical distribution.Only in this way,the internal stress can be symmetrically distributed under the linear load of the disk specimen,and the splitting failure surface will pass through the center of the disk along the loading diameter,so that the theoretical formula of Brazilian splitting can be satisfied;In the direct tensile test,there are three kinds of failure modes and mechanisms tensile failure along the bedding plane,shear failure along the bedding plane and tensile failure of the matrix,and the tensile strength isσt=F/A;Brazilian test cannot blindly expand the scope of application,for the layered rock mass determination of tensile strength,the proposed selection of direct tensile test is strongly suggested.