Protective construction method of excavating large area deep foundation pit in running sand confined water soil layer

Abstract

The invention discloses a protective construction method of excavating a large area deep foundation pit in a running sand confined water soil layer. The method comprises the steps of: firstly, controlling the precipitation depth of the deep foundation pit in a range of 500mm to 1000mm below the excavation surface; disposing a circle of sandless tubular wells around the outer periphery of the deep foundation pit, wherein each sandless tubular well is 2 meters far from the deep foundation pit edge, 6 to 10 meters deeper than the bottom of the deep foundation pit, and 15 to 20 meters far from the neighboring sandless tubular well; laying reinforcing steel mesh sheets and disposing a circle of light-duty wellpoints on an inward side slope of the deep foundation pit; after starting the excavation, arranging a soil nail wall provided with weep holes for anchoring on a side slope of silty sand layer and silty clay layer with silt seam. By the method in the invention, the excavation of the large area deep foundation pit in the running sand confined water soil layer is ensured to be smooth, with no need to enlarge the excavation area. The difficulty of construction and the construction cost are lowered and the construction period is shortened.

Description

technical field [0001] The invention relates to a construction method for excavating and protecting a large-area deep foundation pit in a quicksand pressurized water soil layer. Background technique [0002] Deep foundation pit excavation enclosure is an important process in the process of deep foundation pit excavation. Improper enclosure will cause various failures in the excavation process, and seriously lead to the collapse of deep foundation pits; The enclosure work is particularly important. For example, the soil layer structure at the excavation site is the first layer of cultivated and filled soil layer, the second layer of clay layer, the third layer of silty clay sandwiched with silt soil layer, and the fourth layer of silty fine sand layer; The sand layer is a confined aquifer with a water head height of 6-7 meters and is located in the excavation layer of the deep foundation pit; if the foundation pit enclosure measures at this part are not appropriate, the excav...

AI Technical Summary

Problems solved by technology

Using this method, the construction period and cost increase are relatively large, and it is difficult to guarantee the construction quality of the powder and fine sand layer for foundation reinforcement treatment.

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