基于激光点云数据的裂隙岩体渗流场的无单元法模拟

SIMULATION OF SEEPAGE FIELD FOR FRACTURED ROCK MASS BY ELEMENT FREE METHOD BASED ON LASER POINT CLOUD DATA

利用三维激光扫描技术获取岩体表面高精度激光点云数据,进而得到岩体裂隙网络的几何信息和产状分布情况。研究基于激光点云坐标数据求解含复杂裂隙网络岩体二维渗流场的无单元法,采用罚函数法处理渗流边界条件,并推导无单元Galerkin法的基本方程和积分格式。该方法首先将激光点云数据经坐标投影和抽稀后作为无单元模拟的节点坐标数据;然后结合岩体裂隙网络的几何信息,采用无单元法计算渗流场,进而分析岩体的渗透特性。该方法具有以下优点:(1)可以精确获取高陡边坡的裂隙产状、位置坐标、长度和开度等几何信息;(2)直接将激光点云作为无单元法节点,减少生成裂隙网格和生成节点坐标的工作;(3)将裂隙网络采用裂隙渗透张量表示,可以对非连通裂隙、不同开度和不同充填程度的裂隙进行模拟。在此基础上,应用IDL编制基于海量激光点云数据的岩体裂隙产状分析和无单元法渗流场数值模拟软件LIDAREFM,并计算怀柔县桥梓镇一裸露岩石边坡的渗流场。计算结果表明,该方法是可行、有效的,计算得到的渗流场分布及特性能够反映岩体裂隙网络对渗流场的影响。该方法为研究裂隙岩体真实渗流场分布提供了一种新的研究思路。

The precise point clouds of rock surface which are obtained through three-dimensional laser scanning technology are used to get the geometric information and distribution of rock mass fracture networks. Application of penalty function method to disposing seepage boundary condition is put forward while the basic equations and the integration schemes for seepage based on element free Galerkin method（EFGM） are derived. Data for gridding nodes are obtained from coordinate transformation and vacuation of the laser point clouds. EFGM is used for the acquisition of seepage field distribution in accordance with the geometric information and mass discontinuity occurrence. This method has the following advantages： （1）Accurate fracture occurrence, location, length, opening degree and other geometric information for high and steep slope could be obtained. （2） The gridding nodes for EFGM could be directly transferred from the laser point clouds, reducing the work of generating discontinuity grids and coordinates of nodes. （3） Fracture networks are expressed by fracture permeability tensors and simulation of discontinuity with unconnected, different degrees of openings and filling is performed. On this basis, EFGM software LIDAREFM is developed with clouds handling and numerical simulation of seepage interactive data language（IDL）. The massive laser point can be implemented by LIDAREFM. The numericalsimulation of seepage field distribution for the bare discontinuous rock slope in Qiaozi Town, Huairou County, Beijing is carried out. The results show that the method is feasible and effective and the calculated seepage field distribution and characteristics could correctly reflect the influence of rock fractures on the seepage field of the slope rocks. Meanwhile, this method provides a new research idea for the study of the real seepage field in fractured rock.