基于离散裂隙网络与离散元耦合方法的礼让隧道岩体力学参数确定

为了准确地确定礼让隧道节理岩体力学参数,采用3DEC程序中离散裂隙网络(discrete fracture network, DFN)技术,建立了能反映节理裂隙分布特征的离散裂隙网络模型。在此基础上,结合室内岩石、节理力学试验,运用等效岩体技术及3DEC程序,建立基于离散裂隙网络-离散元(discrete fracture network-discrete element method,DFN-DEM)耦合方法的等效岩体模型,并构建反映工程岩体节理分布特征的多尺度等效节理岩体计算模型;通过对多尺度等效节理岩体计算模型进行单轴压缩试验,获取岩体峰前及峰后的力学性质,分析节理岩体的尺寸效应、各向异性、表征单元体及等效岩体力学参数。结果表明:DFN-DEM耦合技术解决了非贯通节理的建模问题;随着等效岩体尺度增大,节理岩体峰值强度、弹性模量逐渐减小,各向异性特性逐渐减弱,且尺度达到5 m×5 m×10 m趋于稳定得到表征单元体;表征单元体尺度下等效岩体力学参数为弹性模量9 GPa、单轴抗压强度0.7 MPa、内摩擦角25°、黏聚力0.3 MPa、抗拉强度0.12 MPa,与Hoek-Brown强度准则所得力学参数对比,两者较为接近。该法为研究工程岩体的稳定性提供了数据基础。

Determination of Mechanical Parameters of Rock Mass of Lirang Tunnel Based on DFN-DEM Coupling Technology

In order to accurately determine the mechanical parameters of jointed rock mass in Lirang tunnel, the discrete fissure network (DFN) technology in the 3DEC program is used to establish a discrete fissure network model which can reflect the characteristics of the joint fracture distribution. On this basis, combined with the laboratory rock and joint mechanics test, the equivalent rock mass model based on the DFN-DEM coupling method is established by using the equivalent rock mass technology and 3DEC program, and a multi scale equivalent jointed rock mass calculation model reflecting the characteristics of the jointed rock mass distribution is constructed. Then by means of uniaxial compression test on the calculation model of multi-scale equivalent jointed rock mass, the mechanical properties of rock mass before and after peak are obtained, and the size effect, anisotropy, characterization unit and equivalent rock mass mechanical parameters of jointed rock mass are analyzed. The results show that the DFN-DEM coupling technology solves the modeling problem of non penetrating joints. With the increase of the equivalent rock mass scale, the peak strength and elastic modulus of jointed rock gradually decrease, and the anisotropy gradually decreases, and the scale reaches 5×5×10m to stabilize the characterization unit; The mechanical parameters of equivalent rock mass at the unit body scale are as follows: The modulus of elasticity is 9GPa, the uniaxial compression strength is 0.7MPa, the internal friction angle is 25 degrees, the cohesive force is 0.3Mpa, the tensile strength is 0.12Mpa. Compared with the mechanical parameters obtained by the Hoek-Brown strength criterion, the two are relatively close.This method provides a basis for further research on stability of engineering rock mass.