单节理岩体强度试验研究

Experimental Study on the Strength of Single Joint Rock Mass

从理论和经验两方面阐述单节理岩体的强度特征及其确定方法,结合实际的隧道工程岩体,对加工制备的5组完整岩石和含单节理岩石样品进行室内轴向压缩强度试验,应用基于细观离散的三维颗粒流程序PFC3D仿真室内试验结果,从而确定出数值试验中相应岩石和节理的基本细观输入参数。在此基础上,通过对实际工程进行地质调查构建节理岩体结构的理想地质模型,输入岩石与节理的基本细观参数,实现对大尺度单节理岩体进行数值预测的强度试验,并获得实际工程岩体的应力—应变关系及相关的强度特征。试验研究表明:节理的存在降低岩体的强度,改变岩体的延性;岩体中同组的不同节理间存在相互的强度弱化作用,作用的结果导致岩体的总体强度下降,因此简单地分步应用单节理理论预测含多节理的岩体强度是不可行的;基于岩体结构,应用室内试验与数值试验相结合确定大型节理岩体强度的方法是可行的。

The strength characteristics and calculated joints are discussed from theoretical and experimental methods of jointed rock mass including one set of aspects in detail. In addition, the axial compressive test was made for five groups of intact rock samples and rock samples with single joint, which are acquired from the rock mass of tunneling under construction. The experimental results between stress and strain were emulated or reappeared by numerical analysis tool of Particle Flow Code in 3 Dimension （PFCaD） based on the discrete meso-element. As a result, fundamental parameters of the rock and joint for numerical testing are obtained, which can provide possibility for numerical experiment of rock mass. Furthermore, the structure models of jointed rock mass are established according to the practical investigation of engineering geology. Therefore, large-sized jointed rock mass with one set of joints or stratified structure is successfully tested by the numerical experiment on the computer rather than material test machine in the lab or field testing. And then the strength features and relationship between stress and strain of practical rock mass are obtained without a large number of difficult experiments. According to this research, it is found that the joint locating in rock mass reduces the strength of rock mass and alters the ductility of rock mass. Moreover, there is strength reduced effect between joints belonging to the same joint set, which can directly affect strength features so that superposition principle is not fit to the jointed rock mass. Finally, this experimental method for jointed rock mass based on the rock mass structure, lab testing and numerical testing is proved to be feasible, which provides a newly as well as promising idea for determining the strength of jointed rock mass.