裂隙岩体表征单元体的确定及工程应用

Determination of Representative Elementary Volume of Fractured Rock Mass and Its Engineering Application

以某水电站为工程背景,介绍了两种确定裂隙岩体REV的新方法:数字图像处理法和非连续变形DDARF法。依据水电站岩性差异、风化及卸荷程度,将围岩划分为若干工程地质区段并建立随机裂隙网络模型,研究尺寸效应对岩体力学参数的影响规律,获得了REV表征尺寸和等效力学参数;得到岩体的非线性强度准则,嵌入FLAC3D对水电站开挖进行模拟,并监测关键点位移。结果表明:水电站围岩的抗压强度与围压成正相关;洞室开挖对厂房上下游中部和拐角处影响较大,应加强对这些部位的支护;关键点的位移数值结果与现场监测值基本吻合,误差小于5%。数字图像处理法和DDARF法为裂隙岩体REV的确定开拓了新思路,对复杂条件下地下洞室围岩的稳定性分析有广泛的应用前景。

With the engineering background of a hydropower station,two new methods to determine the REV of fractured rock masses are introduced： Digital Image Processing method and discontinuous deformation method DDARF. The hydropower station’s surrounding rock masses are divided into several engineering geological sections based on lithologic differences,weathering and unloading degrees,and a stochastic fractured network model is established,the mechanical parameters’ response law of rock masses with different sizes is studied,the REV size of rock masses and equivalent mechanical parameters are obtained; The nonlinear strength criterion of rock masses is set up,with the criterion nested into FLAC3 D,excavation of hydropower station is simulated,and the displacements of key points are monitored. Results show that the surrounding rock masses’ compressive strength of hydropower station has a positive correlation with confining pressure; the excavation of cavern has large effect on this cavern’s corners and the centres of upstream and downstream,these parts should be strengthen and supported; numerical results and monitoring values of key points’ displacements are in line,with the error less than 5%. The Digital Image Processing method and DDARF method open up a new way of determining fractured rock masses’ REV,which have a broad application prospect for analyzing underground surrounding rock masses’ stability under complex conditions.