What is the regulation of seepage control and drainage arrangement for pump house?

What are the rules for the seepage control and drainage arrangement of the pump house? The following is a detailed introduction of Zhong Da Consulting for your reference.

1, seepage control and drainage layout should be based on the geological conditions of the station, pump head and other factors, combined with the layout of pump house, cross-strait connecting structure and water inlet and outlet buildings, and set up a complete seepage control and drainage system.

2. When the anti-seepage length of the basement of the pump house on the soil foundation is insufficient, reinforced concrete blanket, vertical anti-seepage body (reinforced concrete sheet pile, cement mortar curtain, high-pressure jet grouting curtain, concrete anti-seepage wall, geomembrane vertical anti-seepage structure, etc.) shall be adopted. ) or a combination of the two can be arranged in combination with the bottom plate of the water outlet tank. The bedding should be provided with permanent deformation joints, which are staggered with the permanent deformation joints on the ground of the pump house.

According to the drainage needs, appropriate drainage holes can be set on the bottom plates of the forebay and the inlet tank. A well-graded drainage filter layer should be set at the seepage outlet.

When the foundation of the pump house is medium loam, light loam or heavy sandy loam, the high water level side of the pump house should be covered with reinforced concrete.

When the foundation of the pump house is silty soil, silty fine sand, light sandy loam or light silty loam, the layout of the high water level side of the pump house should be in the form of a combination of blanket and vertical impervious body. The vertical impervious body shall be arranged at the upstream end of the ground of the pump house. On the silt foundation in the earthquake area, the vertical impervious body arranged under the bottom plate of the pump house should be closed around. Silt, silt, light sandy loam or light sandy loam foundation should ensure that the average permeability gradient and escape gradient are less than the allowable values, and a well-graded drainage filter layer must be set at the seepage outlet (including the lateral seepage outlet on both banks).

When end-bearing piles are used under the bottom plate of impervious section, measures should be taken to prevent contact erosion and leakage of the bottom plate.

3. The length of cushion can be determined according to the anti-seepage needs of pump house foundation, which is generally 3 ~ 5 times of the maximum water level difference between upstream and downstream.

The minimum thickness of concrete or reinforced concrete cushion should not be less than 0.4m, the distance between permanent deformation joints can be 8 ~ 20m, and the distance between cushion and wing wall should be small. The joint width can be 20 ~ 30 mm, and the thickness of impermeable geomembrane for cushion should be determined according to the action head, the possible crack width of soil under the membrane, the strain and strength of the membrane, but it should not be less than 0.5 mm, and a protective layer should be set on the geomembrane.

In cold and severe cold areas, for concrete or reinforced concrete cushion, the gap between permanent deformation joints should be reduced appropriately.

4. When the foundation of the pump house is a thin sand layer or gravel layer, and its underlying layer is a relatively deep impermeable layer, a water intercepting ditch or water intercepting wall can be set on the high water level side of the pump house floor. The depth of cutoff trench or cutoff wall embedded in relatively impermeable layer should not be less than1.0m. A drainage filter layer should be set at the seepage outlet.

When the gravel layer of the pump house foundation is thick, the high water level side of the pump house can be arranged in the form of a combination of blanket and suspended cutoff wall, and a drainage filter layer should be set at the seepage outlet.

When the foundation of the pump house is a gravel layer with large particle size or a coarse gravel layer mixed with pebbles, a deep tooth wall or a deep cutoff wall should be set on the high water level side of the pump house floor, and a drainage filter layer should be set at the seepage outlet.

5. When the underlying layer of the pump house foundation is a relatively deep permeable layer, in addition to the provisions of this specification, the impermeability and anti-floating stability of the overburden should also be checked. When necessary, a drainage well or drain ditch can be set at the seepage outlet side, and anti-siltation measures can be taken.

6. When the local foundation bearing layer is interbedded with thin clay and sandy soil, in addition to the provisions of this specification, a vertical impervious body should be added at the front end of the cushion, and a drainage ditch or shallow drainage well should be set at the low water level side of the pump house. And take measures to prevent siltation.

7. The pump house on the rock foundation can be equipped with cement grouting curtain under the side wall of the high water level of the bottom plate according to the anti-seepage needs, and then equipped with drainage facilities.

8. The pump house of high-lift pumping station can be equipped with unobstructed gravity drainage ditch and reliable slope protection measures on its bank slope as required.

9. In all underwater joints with permanent deformation joints, at least one water stop piece (belt) with durable material and reliable performance shall be buried. The intersection of vertical water stop (membrane) and horizontal water stop (membrane) should form a sealing system.

10, the lateral seepage control and drainage arrangement should be determined according to the comprehensive analysis of the head of the pumping station, the soil behind the bank slope and wing wall and the change of groundwater level, and should be compatible with the forward seepage control and drainage arrangement of the pumping station.

1 1. For the combined pumping station with two-way lift, the anti-seepage and drainage arrangement should be based on the pumping station with higher lift, and the two-way arrangement should be reasonably selected.

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