非连续裂隙网络管状渗流模型及其校正

模拟一个野外实际入渗试验的岩体裂隙网络的渗流。在建立渗流模型时，首先产生圆盘形三维裂隙网络，然后令圆盘形裂隙网络退化为三维空间上的管状网络。管元的直径通过模型校正的办法确定，即通过优化方法寻找适当的管元直径，使计算的渗流试验排泄流值能够满意地拟合实测值。由于不可能校正每个管元直径，所以假设在一组裂隙内管元直径服从对数正态分布，这样渗流模型校正参数为每组裂隙管元直径的平均值和标准差。为验证模型的稳定性，通过重复实现产生20个裂隙网络，这20个随机裂隙网络的平均流量与实测值之间的误差为6％。

CHANNEL MODEL FOR FLUID FLOW IN DISCRETE FRACTURE NETWORK AND ITS MODIFICATION

The fluid flow of an actual infiltration experiment performed in fractured rocks is simulated with channel flow model.When building the flow model,a network of disc-shaped fractures is constructed with inverse method firstly.Then,after the removal of unconnected fractures(isolated fracture or fracture clusters not linked to the infinite cluster),the fracture network is simplified to a network consisting of channels in three-dimensional space.When constructing the channel network,for each disc-shaped fracture in the network,nodes are designed at the centers of its intersections with other fractures and the center of the fracture-disc;and each node at intersection-centers is connected to the node at disc center by a channel.The diameters of the channels are modified with observed discharge data.This is a process to modify guessed input channel diameters over likely ranges of values until a satisfactory match between the simulated and observed discharges for the infiltration experiment is obtained.It is impractical to modify the diameter of each individual channel.Consequently,it is assumed that,within a given fracture,the diameters of channels follow the lognormal distribution,so,only the mean and standard deviation of the channel diameters for each fracture set are corrected.To validate the stability of the model,20 fracture networks are generated and the flow in them are investigated.The difference between the measured and the average discharges of the 20 realizations is about 6%.That is,if the discharge of the experiment is predicted with 20 realizations of the stochastic model,the error of the prediction is about 6%.