深埋地下结构工程环境水水质异常成因分析

分析了某抽水蓄能电站地下厂房硐室群开挖引起环境水水质异常的成因。对工程区进行大范围的环境水pH值检测和代表性渗水部位水样的成分分析后发现,环境水的pH值、SO4^2-含量和总铁含量特征在一些部位发生了明显改变：水质呈强酸性、SO4^2-含量和总铁含量高且分布不均匀。结合岩石成分分析和现场黄铁矿矿化点的调查,认为该抽水蓄能电站地下厂房硐室群环境水水质的异常是由地层中不均匀分布的黄铁矿矿化点在开放条件下的氧化造成的,与厂房区锚孔中使用的化学充填材料无关。鉴于当前还没有有效防止强酸性腐蚀的材料,建议加强勘察期间水文地质条件特别是深部水文地质条件的研究,及早掌握和预测深部结构工程开挖、运行过程中由于环境条件改变可能导致的水质改变,以便采取预防措施。

Analysis of Abnormal Quality of Environmental Water in Deep-buried Underground Structures

The causes of abnormal quality of environmental water due to excavation of the underground powerhouse group of a pumped storage power station were analyzed in this study. After detecting the pH values of the environmental water in large extent and analyzing the composition of the water sampled from representative seepage fractions in the engineering area, it was discovered that the pH values, the SO4^2- ion content and the total iron content had changed significantly at some locations of the environmental water body： the water appeared strong acid with irregularly distributed high SO4^2- content and high total iron content. Combining the analysis of rock composition with the investigation of pyrite mineralized points, it is considered that the abnormal quality of the environmental water in the underground powerhouse group of the pumped storage power station was caused by the uneven-distribution of the pyrite mineralized points which had been oxidized in open conditions, and had nothing to do with the filled chemical agents used in anchor holes of the powerhouse. Considering the lack of effective materials of strong acid resistance at present time, the hydrogeology conditions, especially those in the deep stratums, should be studied thoroughly in the site investigation to understand and forecast the possible change of water quality induced by the environmental conditions in the excavation and the operation of the deep-buried underground structures for the application of some preventative measures.