| 摘要 |
PROBLEM TO BE SOLVED: To enhance safety and efficiency of excavation work in an excavation area, and to efficiently prevent an adverse affect, such as ground subsidence, caused by lowering of a water level in peripheral ground, by restoring pumped groundwater into the peripheral ground by a recharge line provided outside a pumping line, while a ground water level in or near the excavation area is lowered by the pumping line annularly surrounding the ground in the excavation area. SOLUTION: A groundwater circulation system is equipped with a plurality of vacuum wells 11 which are arranged in the ground outside the excavation area so as to form the pumping line 10 surrounding the ground in the excavation area, and small-diameter recharge wells 21 which are arranged with a small pitch so as to form the recharge line 20 surrounding the pumping line. While the water level in the ground in or near the excavation area is lowered by operating each of the vacuum wells, the groundwater, which is pumped from each of the vacuum wells, is recharged from the small-diameter recharge well, so that a water curtain with no opening can be formed in the ground outside the pumping line. COPYRIGHT: (C)2005,JPO&NCIPI
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