北方某废弃矿区地下水污染帷幕注浆应急处置研究

Emergency disposal of groundwater contamination curtain grouting in an abandoned mining area in North China

随着我国煤炭资源的枯竭,大量矿山关闭,遗留了广大的地下采空区场地。不少化工企业向废弃矿井内倾倒化学废液等导致了矿区地下水污染事故,威胁地下水水源地的水源安全。针对此类复杂场地条件下污染事故的应急处置案例和经验都非常少,本文以北方某废弃矿区地下水污染注浆帷幕应急处置为例,通过对矿区地质条件的分析、地下空间结构和地下水流场的刻画,构建三维地质模型,以模型为基础设计帷幕注浆工程并实施,研究复杂场地条件下开展帷幕注浆应急处置的重要内容和决定因素,并利用场地地下水样品监测结果,分析研究帷幕内外污染物浓度分布特征及差异,找出地下水运移规律,评价注浆帷幕效果。研究表明:在事故井周边100m范围实施的帷幕注浆工程,对污染物运移的封堵效果显著,帷幕注浆内外污染物含量差距明显。一期检测结果显示帷幕注浆范围内地下水中二氯甲烷浓度最高1390μg/L,帷幕范围外最高浓度仅为8.07μg/L;二期检测结果为污染物检出浓度大于5μg/L的区域全部位于帷幕范围内,帷幕范围外均未检出。同时污染物的分布特征指示着地下水沿巷道运移成为最主要的形式,对地下空间结构的精准刻画是决定帷幕注浆工程成效的重要因素。

With the depletion of coal resources in China,a large number of mines have been closed,leaving a large number of underground goaf sites.Many chemical enterprises dump chemical waste liquor into abandoned mines,which leads to groundwater pollution accidents in mining areas and threatens the safety of groundwater sources.There are very few emergency cases and experiences in dealing with pollution accidents under such complex site conditions.Taking the emergency treatment of groundwater pollution grouting curtain in an abandoned mining area in North China as an example,this paper builds a threedimensional geological model based on the analysis of geological conditions,the description of underground space structure and groundwater flow field in the mining area.Foundation design and implementation of curtain grouting project,study the important content and determinants of emergency disposal of curtain grouting under complex site conditions,and use the monitoring results of groundwater samples in the site,analyze the distribution characteristics and differences of pollutant concentration inside and outside the curtain,find out the law of groundwater movement,and evaluate the effect of grouting curtain.The results show that the curtain grouting project in the area of 100 maround the accident well has remarkable plugging effect on pollutant transport,and the difference of pollutant content between inside and outside the curtain grouting is obvious.The results of the first stage show that the highest concentration of dichloromethane in groundwater is 1390μg/L in the curtain grouting area,and the highest concentration outside the curtain area is only 8.07μg/L.The second stage results show that all areas with the detected concentration of pollutants are greater than 5μg/L are within the curtain area,and none of them are detected outside the curtain.At the same time,the distribution characteristics of pollutants indicate that groundwater migration along roadways has become the most important form.The accurate description of underground space structure is an important factor to determine the effectiveness of curtain grouting project.