基于离散裂隙网络的烟台水封洞库渗水点分析

建立在致密结晶岩地区的地下水封洞库开挖过程中洞室及水幕巷道的渗水具有不均匀性,而现阶段主要在开挖后根据实际渗水量组织施工排水,若排水不及时容易造成洞室或巷道大面积浸水而形成安全风险。为在洞室开挖前对渗水点分布及渗水量进行一定预测,从而提前且合理安排排水工作,降低施工风险,以烟台地下水封洞库丁烷库区为例,在对该库区裂隙调查结果进行一定的统计分区后,采用Monte-Carlo随机模拟方法建立离散裂隙网络模型,通过多次迭代确定裂隙模拟置信区间,并选取在置信区间范围内的裂隙模拟结果按照立方定律求取渗透系数,按区间进行水封洞库渗水点分布区划分,同时与实测大流量渗水区域进行比对,结果发现两者具有较好的一致性,表明该方法能借助前期裂隙统计结果预测洞室开挖后渗水情况,协助组织施工期洞室排水。

Seepage Analysis of the Water-sealed Cavern in Yantai City Based on the Discrete Fracture Network Model

Seepage inhomogeneity is common characteristics in carvens and water curtain tunnels during ex-cavation which are built in compact crystalline rock area.At presentthe site drainage is deployed after the excavation has begun according to the actual seepage quantity.Once the water is not discharged in time,the caves or the tunnels tend to immerse to a large extent with a hysteretic drainage,which may cause safety risk.To forecast the seepage point and its quantity before the caves are dug,so as to arrange reasonably the drainage in advance and lower the constructive risk,this paper calculates and classifies the fracture in the water-sealed cavern of Yantai city and builds the discrete fracture network model based on the stochastic method by Monte-Carlo.With multiple iterations,the paper confirms the confidence interval of the fracture simulation,then calculates the permeability coefficients using cubic law according to the simulated result of fractures which lies in confidence interval.Furthermore,the paper divides seepage points of water-sealed cavern into several parts by the confidence interval and compares with the virtual parts.The results exhibit fine consistency between the simulated and the measured parts,showing that the method can predict the seepage after caving,which helps in site drainage in construction period.