关键词: 基坑工程, 承压水, 水头恢复比, 降压

Abstract: With excavation depth increasing, the problem of confined water has become more and more prominent, which has brought about adverse effect on the surrounding environment, such as bursting in foundation pit. To discover variation of confined water, reduce the amount of pumping, control ground surface settlement and protect the surrounding environment, based on the deep-large-irregular foundation pit Shanghai Museum of Natural History, confined water pumping test was carried out. The test results show that with excavation depth increasing confined water head is also lower; the barrier effect is not obvious if the depth of diaphragm walls inserted confined water layer was less one third than the thickness of confined water layer; head recovery ratio was described water level recovery, reached at 10% after 10 minutes, the ultimate reached at 94.5%; the relieve effect of single well was certain which was not related to the water head of test beginning, the relieve effect of group wells was related to well quantity however the relieve benefit became gradually worse. According to confined water pumping test, pumping wells can be grouped into different combinations; the excavation can be combined with different combinations at different times; then the goal will be achieved that pumping of confined water is released when needed.

Key words: excavation engineering, confined water, head recovery ratio, relieve