The Application Of The Hydrogeochemistry On The Research Of Ground Water System At The Dam Area Of Da Gangshan Hydropower Station

Because there are several periods of tectonic movement and several tectonic zones' development and complex superposition at Da gangshan hydropower staion, geological structure in dam area is great complex and water-bearing media has the characteristic if inhomogeneity, which make it difficult to further clarify the burial condition of different bearing aqueous structure and the development of ground water system at the dam area.For dealing with the difficulties, this paper mainly researches the hydrogeochemistry problems at the hydropower station to supply the evidence for studying its ground water system. Through field investigation and analysis indoor, with studying all hydrochemistry data in detail, including macro components and micro components, the author finds out the hydrochemistry feature of ground water. For further specifying the ground water system, with cluster analysis of macro components of surface water and ground water in total 147 samples and the analysis of micro components, including REE, the main ground water systems are distinguished by and large, especially the ground water system main of fault No. 7 and fault No. 15 water bearing belts which have differences at macro and micro components between the two ground water systems, moreover, the main hydrogeochemistry effects are established such as lixiviation, oxidization, precipitation and mixing effect, especially the mixing effect which result in the complexity of the hydrochemistry of deep bearing tectonic fracture water. Based on them, the hydro geological model of upper dam base is established, meanwhile the author summarizes the hydrochemistry feature of weathering crevice water, surface tectonic crevice water and deep tectonic crevice water.On the base of the study on the hydrogeochemistry at dam area, the author analyzes the last hydrochemistry data of bearing crevice water. From the diagram of Piper and the correlation diagram of Na/Ca and Na, it is known that the deep bearing tectonic fracture water is produced by two sources mix, meanwhile it is found out that there is better hydraulic power connection among bore D46, D503, D211, which shows there is better NNW hydraulic power connection at complex zone making up of fault No. 7, No. 15 and No. 2.