丹巴水电站长引水隧洞涌水量预测

Water inflow predictions of Danba water diversion tunnel

拟建的丹巴水电站引水系统位于丹巴县境内大渡河左岸,该区域河谷陡峻,地质条件复杂,引水系统的渗漏及渗透稳定性是工程建设的关键技术问题之一.依据工程地质与水文地质资料,建立了研究区30.6km范围的有限元模型,并基于工程区的补给、径流、排泄特征,开展了天然渗流场的反演分析.在此基础上,研究了施工期与运行期长引水隧洞的涌水量的沿线分布特征,并与多种涌水量预测值进行了对比研究.研究表明:引水系统总涌水量约为132 875m3/d,隧洞沿线单宽涌水量在石英岩区域较大,有限元结果与经验公式结果较为吻合,证明了计算结果的可靠性.研究成果对工程建设具有一定参考价值.

The Danba water diversion system located in Danba County, Sichuan Province, China, has planned to be constructed in the left bank of the Dadu River. The construction site is of difficult geological conditions and is rich in groundwater; and the control of groundwater inflow to the diversion tunnel be- comes one of the key technological issues. Based on the geographic and geomorphic conditions and hydro- geological data, a three-dimensional finite element mesh is generated; and the initial seepage field at the construction site is back-calculated with the borehole water level measurements. On this basis, the seepage flow rates along the tunnel axis at the operation stage as well as the construction stage are analyzed. The simulation results are compared with the predictions obtained from different kinds of empirical formulas. The results show that the total flow rate is about 132 875 m3/d; and the discharge is relatively larger in quartz area, which is consistent with the predictions of empirical formulas. The methodology presented in this study is useful for predicting the seepage flow rates of long deep tunnels in other projects.