巨厚非均质含水层中超深孔涌水量预测

Prediction of ultradeep pore water inflow in giant thick heterogeneous aq-uifers

解析解模型计算效率高,被广泛应用于估计含水层涌水量。然而,这类模型包含许多假设条件,例如:含水层是均质的、抽水量是常数、忽略井内水头损失等,因此被称为均质模型。事实上,这些假设条件往往得不到满足,导致结果产生不可忽略的误差,尤其是非均质巨厚含水层。同时,均质模型无法估计破碎带的渗透系数与涌水量,不利于解决隧道施工过程中的水患问题。依托新疆天山胜利隧道项目,开展了2次抽水试验。基于综合测井数据和钻孔数据建立地质模型;采用非均质数值模拟方法定量研究超深孔的地下水涌水量。采用第一次抽水试验的观测数据率定模型中的参数,采用第二次抽水试验的观测数据验证模型与率定后参数的合理性。模型反演了破碎带、完整花岗岩和较完整花岗岩的渗透系数,分别为0.00093,0.0005,0.0003 m/d;预测了总涌水量与破碎带的涌水量,分别为14.80,10.46 m^(3)/h,其中破碎带的涌水量占总涌水量的70.676%。野外的观测数据表明超深孔抽水试验过程中井筒内存在水头损失。非均质数值模拟模型比均质模型更能解释超深孔抽水试验数据,均质模型计算的总涌水量结果为18.67 m3/h,高估了涌水量。在隧道施工过程中,非均质模型获取的水动力学参数和涌水量更加可靠。

[Objective]The analytical solution model is computationally efficient and widely used to estimate aquifer surges.Analytical solution models are computationally efficient but involving many assumptions,such as that the aquifer is homogeneous,the amount of water pumped is constant,while the head loss in the well is ignored;these models are often referred to as homogeneous models.In fact,these assumptions are often not met,resulting in nonnegligible errors in the results,especially for heterogeneous giant thick aquifers.Meanwhile,the homogeneous model cannot estimate the permeability coefficient and water inflow of the broken zone,which is not conducive to solve the water problem during tunnel construction.[Methods]In this study,two pumping tests were carried out on the Shengli Tunnel Project in Tianshan Mountain,Xinjiang.A geological model was established based on comprehensive logging data and borehole data;a heterogeneous numerical simulation method was used to quantitatively investigate the amount of groundwater inflow in bore holes.The parameters in the rate determination model of the observation data of the first pumping test were used,and the rationality of the model and the postrate parameters were verified by the observation data of the second pumping test.[Results]The permeability coefficients of the fracture zone,intact granite and relatively intact granite were inverted and were 0.00093 m/d,0.0005 m/d and 0.0003 m/d,respectively.The total water inflow and the water inflow of the fracture zone were predicted to be 14.80 m^(3)/h and 10.46 m3/h,respectively,of which the water inflow of the broken zone accounted for 70.676%of the total water consumption.[Conclusion]Field observations revealed head loss in aan ultradeepbore hole during pumping test.The heterogeneous numerical simulation model can explain the ultradeep hole pumping test data better than the homogeneous model,and the total water inflow calculated by the homogeneous model is 18.67 m3/h,which overestimates the water inflow.During tunnel construction,the hydrodynamic parameters and water inflow obtained by the heterogeneous model are more reliable.