莲花台水电站岩溶发育特征及工程意义

Karst features of the Lianhuatai hydropower station and engineering significance

根据地质调查和勘探资料,阐明莲花台水电站坝址区岩溶发育形态、规模及空间展布特征,归纳岩溶发育规律。结果表明:坝址区岩溶发育主要受岩性和地质构造控制,岩溶现象分布范围广,岩溶发育较为密集,具有垂向分带性及空间分布不均匀性的特征;岩溶发育对工程的影响主要表现在岩溶渗漏和岩溶塌陷稳定问题两个方面,岩溶渗漏可能造成电站无法达到设计正常蓄水水位,岩溶空间的存在可能引起坝基抗滑稳定问题。因此,建议设置防渗帷幕,并对坝基开挖揭露的溶洞进行换填加固及固结灌浆等工程处理措施,通过处理,可有效避免岩溶发育对工程的影响。

The Lianhuatai hydropower station is located in the main valley section of the Danjiang river in Shangnan county,Shaanxi Province.Based on geological survey and exploration data,this paper presents the pattern, scale and distribution of the karst in the area of the dam and summarizes the development characteristics of the karst.The results show that karst development in the dam area is mainly controlled by lithology and geological structures.The karst is widely developed and concentrated at some places,characterized by vertical zoning and uneven spatial distribution.The influence of karst on construction mainly includes two aspects,karst seepage and karst stability,the former of which may cause the power station to fail to reach the designed normal water level. The karst caves may lower the anti-sliding stability of dam foundation.Therefore,it is suggested to set up antiseepage curtains,and to replace and reinforce the karst caves exposed by dam foundation excavation with consolidation grouting.The influence of karst on the project can be effectively avoided with engineering treatment.