Well point dewatering methods include: light well point, jet well point, electroosmosis well point, tube well point and deep well point. The selection of well point dewatering method and equipment can be determined after technical and economic comparison according to the permeability coefficient of soil layer, required dewatering depth and engineering characteristics.
Extended data
1. Light well point: Light well point is to bury well point pipes (steel pipes with a diameter of 38-5 1 mm and a length of 5-7 m) into the aquifer at regular intervals around the foundation pit, and continuously extract groundwater from the well point pipes with pumping equipment, so that the original groundwater drops below the pit bottom. In the process of construction, water should be pumped continuously until the construction is completed.
2. Jet well point: If light well points are still used and multi-level well points are adopted, it will increase the amount of foundation pit excavation, prolong the construction period and increase the number of equipment, which is obviously uneconomical. Therefore, when the precipitation depth exceeds 8m, the jet well point should be adopted, and the precipitation depth can reach 8-20m. Water injection point equipment is mainly composed of water injection pipe, high pressure water pump and pipeline system.
3. Electro-osmotic well point: For the soil with small permeability coefficient (k is less than 0. 1m/d), this method can be adopted due to the capillary action of tiny gaps between soil particles.
Electroosmosis well point takes well point pipe as cathode, and steel bar or steel pipe is inserted into it as anode. After introducing DC, under the action of electric field, the water in the soil will accelerate to penetrate into the cathode and flow to the well point pipe. This method consumes a lot of electricity and is only used under special circumstances.
4. Tube well point: the tube well point is to set a tube well at regular intervals along the foundation pit, and each tube well continuously pumps water with a separate pump to reduce the water level. This is more suitable for the case of a large amount of groundwater.
5. Deep well point: When the precipitation exceeds 15m, the general submersible pump and centrifugal pump can't meet the requirements of well point precipitation of tube well, so we can increase the depth of tube well and use deep well pump instead.
Deep well points can generally reduce the water level by 30-40 m, and some can even reach1000 m. There are two common deep well pumps: deep well pumps with motors on the ground and deep well submersible pump (submersible deep well pumps).
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