Time to stop dewatering of foundation pit during subway station construction: from the end of foundation pit excavation to the completion of cushion construction. Foundation pit precipitation mainly includes surface precipitation and groundwater, and there are three main types of groundwater:

First, it refers to all the water that is obviously different from the surface water, especially the part of the aquifer that is saturated with water.

The second is downward flow or infiltration, which permeates soil and rocks and provides water for springs and wells.

The third is water stored in underground rock caves and cracks that make up the earth's crust.

Matters needing attention in foundation pit construction

1, before the actual operation of the foundation pit, it is necessary to check the horizontal elevation of the control pile to ensure normal operation, and then find its setting-out position according to the design drawings to ensure that other standards meet the requirements.

2. If the foundation pit starts construction, it should be implemented continuously to shorten the process. Corresponding protective measures should be taken during construction to prevent groundwater from flowing into the pit and prevent landslides or landslides. Moreover, the distance should be controlled within three meters when the map is pushed on site, and there can be no mound within three meters, otherwise the construction effect will be worse.

3. When excavating the foundation pit, be careful not to dig too deep at a time, and carry out it according to the special construction scheme of earthwork excavation.