岩石抗拉强度特性的劈裂试验分析

采用钢丝垫条、直接加压、弧形模具的加载方式，对砂岩、泥岩进行了大量的劈裂试验。结果表明：采用不同的加载方式，测定的岩石抗拉强度差别很大。其中，弧形模具加载测得的抗拉强度最大，其次是直接加压的方式，钢丝垫条加载方式测得的抗拉强度最小。通过对劈裂试验试件内应力场的分析，用MATLAB程序绘制出试件内应力场解析解的分布图，结合FLAC^20的模拟结果，认为对于不同的岩石，试件的破坏方式不同，硬岩不一定是从试件中心首先破坏，而是试件轴线上的某个部位；软岩和层状岩石则因不同的加载方式有不同的破坏方式。不同加载方式测试结果产生差别主要是因为加载板和试件间存在摩擦力等因素影响，随后给出了硬岩不同加载方式时抗拉强度的计算公式。

Splitting Test and Analysis of Rock Tensile Strength

Three different loading methods, i.e. arc-holder, direct-holder and middle-steel-wire-holder, are used to determine the tensile strength of sandstone, mudstone. The results show that there is a great difference of tensile strength for the same rock by using different loading methods, the measured tensile strength for arc-holder loading method is maximum, one is middle for direct-holder loading method and one for middle-steel-wire-holder is least. The stress field and the failure patterns of the rock specimens are analyzed base on MATLAB and FLAC2D. The results show that for hard rock the initial failure is not sure at the center of specimen, but may is at the some place along the axial line of specimen; for soft rock and layered rock the failure patterns are different rocks when different loading methods are used. The differences of the tensile strengths measured using different loading methods are caused by the friction existing between the holder and the specimen and so on. This paper gives the calculation equation of rock's tensile strength for different loading methods.