| The water diversion Project of the central region of Yunnan is a major deployment related to people’s livelihood conditions. This project plan to transport the water from Jinsha river Jiangbenzi section which is in the Diqing Zhou deqing County to Lijiang, Dali, Chuxiong, Kunming, Yuxi, Honghe city, Included six cities and thirty counties, and the diversion line length of848.18km.There is a large area of karst in Dali section, Haidong tunnel length24km, through the karst region length of about20km, in He Village section, the karst hydrogeological conditions is most complex and strongly constructed along the tunnel and down a few dense5km range of regional as well as dozens of smaller faults rupture. Tunnel site lithology wide range of areas, including a variety of soluble and non-soluble rock formations, intrusive dykes alternately exposed.This paper addresses the regional geology from the tunnel to start by analyzing the results karst morphogenesis, structural features and characteristics of the regional hydrogeological conditions, groundwater grasp structural characteristics, groundwater hydrodynamic conditions, groundwater recharge, runoff and discharge rules, combined with the construction of dynamic engineering solutions and dynamic characteristics of groundwater, groundwater use three-dimensional numerical simulation software Visual Modflow dynamic process tunnel site groundwater seepage field simulation, and the use of different methods to predict water inflow to the tunnel and come to a reasonable tunnel water inflow to arrive changes in the area under different conditions seepage field, regional watershed change process, landing funnel range. Predict the evolution of the hydrogeological conditions of the tunnel site, and the following conclusions:(1) Tunnel site karst development, the development of various types of karst phenomena complete tunnel through karst passages of about20km. Tunnel site groundwater mainly occur in P1ã€C2+3ã€D1q and other karst formations and fault fracture zone, fractured zone near intensive groundwater types of karst bedrock fissure water and water-based. Distributed in karst folds and faults end with the formation of water-rich, well-endowed water conditions, as well as the advantages of groundwater seepage channel, tunnel excavation to expose such lots Gushing water can easily lead to accidents.(2) Study the groundwater system is divided into two zones, belonging to the Lancang River and Jinsha River, the system can be under natural conditions were subdivided into two and five sub-units. Tunnel site belong to lift the state of tectonic erosion alpine topography, groundwater recharge, runoff and discharge mainly due to topography and tectonic zone control. Meteoric recharge groundwater, mainly through the valley surface depressions local sinkholes and underground channel runoff.Recharge area, mostly high-altitude tunnel site, runoff pathways smooth, short cycle, water-rock interaction is weak.(3) According to the infiltration of precipitation, groundwater dynamics and numerical simulation method was used for the tunnel excavation segment Haidong water inflow forecasting, resulting rainfall infiltration method results:DLâ…¡2+658-3+306, DLâ…¡4+761-4+990segment maximum water inflow per unit length normal water inflow was4.75m2/d,4.49m2/d. The groundwater dynamics displayed DLâ…¡8+804-9+254and DLâ…¡15+698-18+148larger unit length normal water inflow were10.1m2/d and14.7m2/d. Numerical simulation method is mainly combined under different conditions, changes in water inflow different partitions, Zone4, Zone5case2to3working conditions under the conditions of water inflow from6707.797m3/d,6154.795m3/d sudden increase14519.15m3/d,12173.67m3/d, Zone3,Zone6in case3to4working conditions. Gushing water conditions have sudden increase in the phenomenon, the main tunnel excavation process with a combination of changes in lithology, faults and seasonal distribution of rainfall increases and other factors.(4) The use of Visual Modflow groundwater seepage field simulation software for simulation under different working conditions forecast diversion tunnel, a condition derived conditions, natural seepage field changed little, with the condition continues, the area under case2conditions watershed Village He, westward migration, dug under the conditions in paragraph3color watershed conditions gradually began to shift eastward; under condition4, condition5conditions reveal small changes in water level has been the construction segment, focused on seepage field changes are construction paragraph, it is also continuing to expand the scope of the cone of depression, the impact on the surrounding groundwater environment; natural seepage field after the completion of two years is expected to resume simulation games restored to natural seepage seepage field state. |
