中文摘要：

某填埋场是国内首批在场底铺设复合衬垫系统的大型卫生填埋场,该场垃圾坝前堆体边坡于2008年6月连续强降雨期间发生失稳事件。介绍该堆体边坡失稳过程的现场监测结果,包括坡面水平位移、深层侧向位移和渗滤液水位。基于监测数据,开展堆体边坡稳定性反分析工作,探讨复合衬垫系统界面抗剪强度取值方法,提出抽排竖井迫降水位、铺膜防渗等应急抢险措施。现场监测和理论分析结果表明：堆体边坡中高渗滤液水位是导致其失稳的关键因素,堆体边坡水平位移速率和渗滤液水位高度呈明显正相关关系;该堆体边坡失稳模式是沿场底复合衬垫系统中软弱界面的深层滑移;斜坡场底上复合衬垫系统在滑移过程中发生位移-软化效应,其界面强度介于峰值强度和残余强度之间;抽排竖井迫降水位是最直接、有效的应急抢险措施。

英文摘要：

The landfill studied in this paper is one of the earliest sanitary landfills with composite liner system installed in China.A slope failure took place in the landfill as a result of successive heavy rainfalls in June 2008.A field monitoring program was carried out to record the slope failure process.The monitoring items include surface horizontal displacement,deep lateral displacement,and leachate level within the slope.On the basis of the monitoring results,back analyses were carried out to access the slope stability,as well as to determine interface shear strength of the composite liner system.This paper also report the emergency measures taken for preventing further catastrophic failure of the huge landfill.The field monitoring and theoretical analyses came to the following conclusions.The high leachate level,which was found to be closely correlated with the measured displacement rate observed in the landfill is a major factor leading to the slope instability.The measurement of deep lateral displacement indicated that the slip took place along the weak interface of the composite liner system at the bottom of landfill.The significant lateral movement of waste body resulted in a displacement-softening effect on the interface strength of composite liner system,and hence the shear strength along the liner was in between the peak and residual strength.Drawdown of leachate level by pumping from vertical wells was found to be the most effective and workable emergency measure.