垃圾填埋场渗滤液穿过垂直防渗帷幕的渗漏分析

为避免垃圾填埋场内的污染物对地下水造成污染,填埋场常采用垂直防渗帷幕.目前,我国南方的垃圾填埋场内渗滤液水位普遍较高,在高水头作用下污染物可能透过灌浆帷幕渗漏从而污染周边环境.分析了对流、扩散和吸附作用对污染物迁移的影响规律,以苏州七子山填埋场为例,分析了高水头作用下渗滤液透过防渗帷幕的渗漏,通过现场测试进行了验证,研究了灌浆帷幕渗透系数和灌浆深度对渗漏的影响.结果表明,在高渗滤液水位下,对流对污染物迁移起主导作用.实际工况下污染物穿过防渗帷幕需 19.5a,污染区域主要集中在场底含碎石粘土层中,目前污染物尚未渗漏至防渗帷幕下游,分析结果与现场实测结果一致;若防渗帷幕渗透系数能达到标准,则穿过防渗帷幕的时间将延长至填埋场稳定化之后,从而大大降低污染周边环境的可能性;但若帷幕灌浆深度不足,这一时间又将缩短至7a.防渗帷幕渗透系数和灌浆深度的控制对防止污染物向下游地区渗漏极为关键.

Transport of leachate through vertical curtain grouting in landfills

Vertical curtain grouting is often constructed to prevent contamination of ground water by landfill leachate. The leachate water levels in landfills in southern China are generally high, however, and contaminants in such a landfill may leak through the vertical curtain grouting and give rise to environmental problems. The Qizishan landfill in Suzhou was taken as an example to investigate leakage of leachate through the vertical curtain grouting. The influence of advection, diffusion and adsorption on transport of contaminants was analyzed and the influence of permeability and depth of the curtain grouting on leakage were analyzed The results show that advection plays a key role when the leachate water level is high. It takes 19.5a for the contaminants in the landfill to transport through the curtain grouting in the present conditions. The contaminated zone is mainly located in the silty clay beneath the waste, consistent with field investigations. If the permeability of the vertical curtain grouting reaches 10-7cm·s-1, leakage through the curtain grouting will not occur before stabilization of the landfill. But the leakage time will be shorten to 7a if the depth of the vertical curtain grouting is inadequate. Permeability and depth of the curtain grouting are critical to transport of leachate.