止水不良孔导致地下水串层污染的机制研究——以衡水某试验孔为例  

Mechanism of cross strata pollution of groundwater caused by borehole with non-sealing walls: a case study of a test hole in Hengshui City

作　　者：李敏敏[1] 成建梅[1] 李莎[1] 郭达鹏[1] 

机构地区：[1]中国地质大学(武汉)环境学院,湖北武汉430074

出　　处：《水资源保护》2016年第3期14-18,43,共6页Water Resources Protection

摘　　要：华北平原长期存在＂上咸下淡＂的水质格局,近年来,咸水下移问题不断威胁深层淡水资源。根据衡水市某止水不良孔（GK井）修复前后其周边观测孔（XK4井）内水质变化情况,通过构建考虑钻孔串层污染的溶质运移模型,对止水不良孔作为优势通道引导咸水下移的机制进行了研究。结果表明：原本水力联系微弱的相邻含水层通过止水不良孔发生了越流,上层咸水在水头差作用下沿井管下移,经滤水管进入淡水层,导致下层淡水迅速咸化;GK井在14个月内形成的污染晕半径为20~75 m,导致XK4井地下淡水矿化度在5个月内升高约5倍;GK井封填后,污染物在水动力作用下发生扩散、稀释,被污染淡水在4个月后又恢复至原有浓度。止水不良孔造成的串层污染不容小觑,应及时发现及早治理。The phenomenon of salt water distributing in the upper aquifer and fresh water distributing in the lower aquifer exists for a long time in North China Plain. Nowadays,fresh water in the lower aquifer is threatening by the downward migration of salt water. Based on the water quality change around the borehole XK4 before and after the borehole GK with non-sealing walls being repaired,the mechanism of salinization caused by the borehole with nonsealing walls was investigated by building the solute transport model considering cross strata pollution. The results show that the transfluence occurs between the adjacent aquifers,which have faint hydraulic connection,through the borehole with non-sealing walls. Salt water in the upper aquifer migrates downward along the well tube and enters into the fresh water aquifer causing the salinization. The radius of the pollution halo of the borehole GK reaches 20~ 75 min 14 months,and the mineralization degree of water in the borehole XK4 increases by five times in five months. After the borehole GK was filled,the pollutant diffused and diluted,and the fresh water recovered to the original concentration in four months. The cross strata pollution caused by the borehole with non-sealing walls should attract enough attention and corresponding measurements should be taken.

关 键 词：止水不良孔 串层污染 淡水咸化 数值模拟 衡水市 

分 类 号：P641[天文地球—地质矿产勘探]