关键词: 井网, 地下水动态, 三峡

Abstract: The Three-Gorges well network is the first well network in China established specially for the purpose of monitoring the groundwater precursors of reservoir-induced earthquake. The basic consideration of the establishment of this well network is based on the fact that the seismic event of certain magnitude induced by the storage of reservoir may cause the changes of stress and strain states of the aquifer, as well as the corresponding pore water pressures. The number and spacing of the wells are determined according to the magnitude of earthquake(M_S), the length of seismogenic fault(L)and the variation range of stress strain field(R). The selection of well locations is based on the groundwater behaviors sensitive to earthquakes. Such peculiar tectonic sites as the termination, inflection and junction of fault zones are selected for well location. The depth and structure of the wells are decided according to the requirement that the well may reveal well enclosed confined aquifer and minimize the influence of surface water and hydro atmospheric factors on the premise of limit funds. According to the afore mentioned considerations, 4 wells are drilled at the dam site and 4 wells at the head of the Three-Gorges Reservoir. The depths of the wells are between 100～ 200m, and all the wells expose well enclosed confined aquifer. Primary observations show that the arrangement of the Three-Gorges well network and the establishment of the observation wells are relatively successful. They form a good base for monitoring the precursor of reservoir-induced earthquake.

Key words: well network arrangement, observation well, ground water behavior, Three-Gorges area