甘肃徽县通天坪金矿尾渣堆场变形原因分析

Causal Analysis on the Deformation of Tailings Stacking Dam in the Tongtianping Gold Deposit in Hui County,Gansu Province

2008年“9．8”山西襄汾尾矿溃坝事故造成281人遇难的特大灾害给中国尾矿坝（库）的安全管理烙上了一次深刻的印记。据有关研究，尾矿溃坝事故造成灾害的主要原因是坝体的稳定性不足和违规建设等。笔者以通天坪金矿尾矿坝（库）为例，进行库坝稳定性、建设程序和安全防治措施分析，以增强对尾矿库建设安全和管理的重视。甘肃徽县通天坪金矿尾渣堆积坝地基土为强度很低的粉质黏土，承载力特征值为80～100kPa，高度20．0m，初期坝采用粉质黏土堆筑，后期的堆积坝以初期坝为基础，生产期间用压滤干尾砂采用上游式尾矿筑坝法堆筑。尾渣堆场地段地下水较丰富，地下水位埋深在地表附近呈溢出泉出露，坝基土和坝体均为持水性强、渗透性差的黏性土体，不仅地形呈约为10°的斜坡，坝基土体也呈5°～10°倾斜状分布。由于对软弱的地基土未做处理，坝基和坝体排水措施不力，导致投入运营不久坝体和坝前地表发生隆起、开裂、塌陷等变形破坏，严重影响了坝体的正常使用。经后期的补充勘察，提出的地基加固、坝体排水等补救措施实施后，经近2年的监测，坝体稳定，运行正常。

For the tailings stacking dam of the Tongtianping gold deposit in Hui County of Gansu Province, the foundation soil is silty clay with very low strength, its characteristic value of bear- ing capacity is 80-100kPa. When the initial dam is lower than 20.0m, it is piled up by silty clay, and then the later fill dam is built on the basis of the initial dam. During the production, the filter dry backfilling materials are used piled up by using the up-stream type tailing damming method. The groundwater of tailings stacking yard is rich. If the buried depth of groundwater level is nearby the earth＇s surface, the groundwater will expose as the boundary spring. Both the damfoun poor uted dation perme soil and the ability, both as a slope with ang dam body are the co of them have a slope le of 5°-10° Due to hesive soils with strong water-holding capacity and of about 10°, and the dam foundation soil is distrib- the weak foundation soil has not been processed, the drainage measures of dam foundation and dam body are very poor, leading to the uplift, cracking and collapse deformation damage for the dam （that was operated shortly before） body and dam surface, seriously affecting the normal use of the dam body. Through carrying out the later sup- plementary investigation, the remedial measures, such as foundation reinforcement and dam drainage, had been putted forward. After nearly two years of monitoring, it＇s proved that the dam body is steady and its operation is fine.