3-D fracture network dynamic simulation based on error analysis in rock mass of dam foundation

Accurate 3-D fracture network model for rock mass in dam foundation is of vital importance for stability,grouting and seepage analysis of dam foundation.With the aim of reducing deviation between fracture network model and measured data,a 3-D fracture network dynamic modeling method based on error analysis was proposed.Firstly,errors of four fracture volume density estimation methods(proposed by ODA,KULATILAKE,MAULDON,and SONG)and that of four fracture size estimation methods(proposed by EINSTEIN,SONG and TONON)were respectively compared,and the optimal methods were determined.Additionally,error index representing the deviation between fracture network model and measured data was established with integrated use of fractal dimension and relative absolute error(RAE).On this basis,the downhill simplex method was used to build the dynamic modeling method,which takes the minimum of error index as objective function and dynamically adjusts the fracture density and size parameters to correct the error index.Finally,the 3-D fracture network model could be obtained which meets the requirements.The proposed method was applied for 3-D fractures simulation in Miao Wei hydropower project in China for feasibility verification and the error index reduced from 2.618 to 0.337.

考虑地震波折射的层状介质微震源定位方法

现有的微震源定位方法假设地震波沿直线传播,定位结果往往不能满足精度要求,为此建立一种新的微震源快速定位方法--地震波最小走时面法。该方法考虑波的传播符合斯涅尔定律而提出地震波最小走时路径射线传播平面的假设,通过旋转坐标系,将地震波三维传播路径转换为二维平面传播路径,实现平行分层岩体中相对准确的地震波初至到时计算,并在三层水平模型中采用改进的遗传算法进行微震源的优化求解验证假设的有效性,同时对影响定位精度的因素进行分析。结果表明,最小走时面法所得地震波走时明显优于传统最短几何路径走时计算方法,二者的差值是微震源和传感器连线倾角α和间距L的函数;该算法在多层岩体的微震源定位中具有良好的定位精度,且不受介质波速比的影响。