Study On The Runoff Model Of Karst Synclinal Water-storing Structure And Geochemical Simulation

The synclinal water-storing structures are really been found during the tunnel and hydro-power station constructions in karst region. The so called synclinal water-storing structure refers to syncline structure or tectonic basin which can concentrate and store the groundwater. And the feature of groundwater within these structures depends on hydrologic barrier overlying and the landform. For it is significant to study the runoff model within the structure, this paper takes many engineering examples of karst region in the southwest China, and systematic analysis has been done as follows:(1) The engineering examples been chosen are Maoba Syncline in Yuanliangshan railway tunnel, Xuyong-Changguansi Syncline in Xinba reservoir, Jianwu Syncline in Pingshan reservoir, Dabaogai Syncline in Baoshan railway tunnel, Jiezipo Syncline in Dazhushan railway tunnel and Yongsheng Syncline in Xiluodu hydropower station. Studies have been done in many aspects, such as formation lithology, structural feature, aquifer, groundwater character and so on.(2) Based on chemical and hydrodynamic characteristics of the karst groundwater, the groundwater system has been divided. As a result, the runoff model of groundwater within synclinal water-storing structure can be summarized into four types, which are runoff along the synclinal axis, runoff within each flank, runoff across the synclinal axis and the combined type.(3) The runoff model types differentiate from each other in both formation lithology and structural feature of the synclinal water-storing structure, and chemical and hydrodynamic characteristics of the karst groundwater.(4) According to the hydrogeology condition of the water-storing structures, the runoff model of Maoba Syncline is along the synclinal axis, Xuyong-Changguansi Syncline is within each flank, Jianwu Syncline, Dabaogai Syncline and Jiezipo Syncline are crossing the ynclinal axis, Yongsheng Syncline is the combined type.(5) On basis of the above analysis, the simulation path and potential phase can be chosen. Using the software of PHREEQC (version 2.16.04), the evolution process of karst groundwater in water-storing structures is quantitatively calculated by the method of inverse modeling. Meanwhile, the division of runoff model within the synclinal water-storing structure of each engineering examples are verified.?...