Yongchuan Zhao (Yunnan Institute of Water & Hydropower Engineering Investigation, Design ang Research, Kunming 650021,China)
Objectives of the study
Limestone and dolomitic limestone are widely exposed in the reservoir area of the Dehoureservoir (see Fig. 1), the karst development is strong,andthe karst hydrogeological condition is complex,thereservoir leakage is the most important engineering geological problem,itis also the key technical problem of reservoir. From the aspects of stratum lithologic, rock mineral composition and chemical composition, geological structure, neotectonicmovement and planation surface, modern river discharge datum and so on,themain factors controlling karst development were studied. According to the karst morphology, the elevation of denudation surface, the karst hydrodynamic conditions and other factors,comparativeanalysis of evolution history of regional karst development,thekarst development law of Panlongriver, a tributary of Red river basin, was divided into stages,thekarst development in the project area has experienced plateau period, Pingyuanperiod and Panlongriver period since the cenozoicera. The vertical zoning law of karst in Panlongriver period and the karst development characteristics of seepage section were studied,andthe variation law of deep karst zone with depth was studied,withthe increase of depth, the number of karst caves and the degree of karst development decreases. The research results can provide support for determining the bottom boundary of anti-seepage and the basis for determining the anti-seepage treatment scheme.
Conclusions
1) Based on the basic geological engineering condition, combining with the karst evolution history, the study area’s karst development is staged, which is beneficial to the further analysis.
2) The basic investigating and advanced geophysical method is comprehensively used to obtain the karst development condition.
3) Considering the lithology, geological structure and so on, the study area is divided into grid area. And targeting investigation is conducted successfully. The analysis and diagnosis of the reservoir’ leakage is implemented efficiently and accurately.