CN-122013802-A - Drainage construction method for foundation pit of high-water-level fan foundation in desert sand-blown region

CN122013802ACN 122013802 ACN122013802 ACN 122013802ACN-122013802-A

Abstract

The embodiment of the application provides a drainage construction method for a high-water-level fan foundation pit in a desert sand-blown region. In the excavation process of the foundation pit, each time a layer of foundation pit is excavated, namely, an annular drainage ditch extending along the edge line of the bottom of the foundation pit and a water collecting well communicated with the annular drainage ditch are arranged at the bottom of the current foundation pit, accumulated water collected in the water collecting well is extracted and discharged through drainage equipment to carry out drainage descending on the current foundation pit, when the water level of the water descending to the bottom of the current foundation pit meets the preset dryness requirement, the water descending is carried out on the basis of the current foundation pit and based on the same principle, then the water descending is continued until the elevation of the water descending to the bottom of the foundation pit reaches the design elevation. According to the method, the foundation pit is effectively drained in the process of building the foundation pit of the fan, so that the construction safety in the process of building the foundation pit of the fan in a high-groundwater-level area can be improved.

Inventors

Wei Gaoshuai
SHEN YAJUN
FU SHAOWEI
QI LINPAN
ZHAO YANG
ZHANG JIANHONG
DAI YUWEI
DONG ZHONGHONG

Assignees

中国电建集团西北勘测设计研究院有限公司

Dates

Publication Date: 20260512
Application Date: 20260317

Claims (10)

1. The construction method for lowering and draining the foundation pit of the high-water-level fan foundation in the desert sand-blown region is characterized by comprising the following steps of: Excavating downwards a certain depth along the upper port line of the foundation pit in the selected foundation site to form the foundation pit; An annular drainage ditch extending along an edge line of the bottom of the foundation pit is arranged at a preset distance from the bottom of the foundation pit to the toe; a plurality of water collecting wells which are uniformly distributed along the edge line of the bottom of the foundation pit and are communicated with the annular drainage ditch are arranged; Extracting and discharging accumulated water collected in the water collecting well through drainage equipment until the groundwater level at the bottom of the foundation pit meets the preset dryness requirement; Further excavating downwards a certain depth on the basis of the current foundation pit, and returning to the step of arranging an annular drainage ditch extending along the edge line of the bottom of the foundation pit at the preset distance from the bottom of the foundation pit to the toe of the slope until the elevation of the bottom of the foundation pit reaches the design elevation; And under the condition that the elevation at the bottom of the foundation pit reaches the designed elevation and the foundation pit passes through the test groove, the construction of the fan foundation is performed in the foundation pit.
2. The method of claim 1, wherein after digging down to the bottom elevation of the foundation pit to the design elevation, the method further comprises, prior to performing construction of the fan foundation within the foundation pit: The bottom of the foundation pit is provided with a plurality of simple drainage ditches which extend from the center of the foundation pit to the edge of the foundation pit and are communicated with the annular drainage ditches at the bottom of the foundation pit, the bottom of the simple drainage ditches is provided with slopes, the height of the bottom of the simple drainage ditches gradually decreases along a first direction, and the first direction is the direction pointing to the edge of the foundation pit from the center of the foundation pit.
3. The method of claim 2, wherein after providing a plurality of simple gutters extending from the center of the pit to the edge of the pit at the bottom of the pit and communicating with the annular gutters at the bottom of the pit, the method further comprises, prior to performing the construction of the fan foundation in the pit: the method comprises the steps of covering waterproof geotechnical cloth on the bottom of a foundation pit, wherein the waterproof geotechnical cloth covers a first area, the first area is an area formed by surrounding a first edge line of an annular drainage ditch positioned on the bottom of the foundation pit, and the first edge line is an edge line of one side of the annular drainage ditch, which is close to the center of the bottom of the foundation pit.
4. The method of claim 1, wherein after providing the annular drainage ditch extending along the edge line of the bottom of the foundation pit and providing the plurality of water collection wells evenly distributed along the edge line of the bottom of the foundation pit and in communication with the annular drainage ditch, the method further comprises, prior to drawing and draining the accumulated water collected in the water collection wells by the drainage device: geotextile is paved on the inner wall of the annular drainage ditch and the inner wall of the water collecting well; and paving crushed stone with a certain thickness at the bottom of the water collecting well after paving geotextile so as to form a water filtering layer.
5. The method of claim 1 or 4, wherein the inner wall of the annular drain is a reverse filter layer formed by pebble construction.
6. The method according to claim 1 or 4, wherein the drainage device comprises a plurality of submersible pumps respectively arranged in the plurality of water collecting wells, and a plurality of drainage pipes with one ends respectively connected with the plurality of submersible pumps and the other ends extending to the outside of the foundation pit; The water accumulated in the water collecting well is extracted and discharged through the drainage equipment until the groundwater level at the bottom of the foundation pit meets the preset dryness requirement, and the method comprises the following steps: after the construction of the water collecting well is completed, starting the submersible pump to extract and discharge accumulated water collected in the water collecting well; periodically detecting the underground water level at a preset water level observation point to determine whether the underground water level at the bottom of the foundation pit meets the dryness requirement, wherein the water level observation point comprises a plurality of water level observation points respectively arranged at the central position and the edge position of the bottom of the foundation pit; And under the condition that the groundwater level at the bottom of the foundation pit meets the dryness requirement, recovering the submersible pump and the drain pipe, and executing the step of further excavating downwards to a certain depth on the basis of the current foundation pit.
7. The method of claim 6, wherein a total daily displacement of the plurality of submersible pumps is not less than a first water volume that is 1.5 times a predetermined estimated water penetration of the foundation pit within the base site.
8. The method of claim 6, wherein the method further comprises, prior to excavating a depth down the pit upper port line in the selected foundation site to form the pit: an annular water blocking table extending along the upper opening line of the foundation pit and having a certain distance with the upper opening line of the foundation pit is arranged outside the upper opening line of the foundation pit; And a water scattering slope surface is formed on the outer side of the annular water blocking table.
9. The method of claim 8, wherein after completing construction of the fan foundation, the method further comprises: Backfilling earthwork of the foundation pit, and dismantling a submersible pump and a drain pipe which are arranged in the foundation pit; And after the earth backfilling is completed, the annular water retaining table is disassembled.
10. The method of claim 1, wherein the depth is no more than 1.5 meters when further excavated downwardly to a depth based on the current foundation pit.

Description

Drainage construction method for foundation pit of high-water-level fan foundation in desert sand-blown region Technical Field The application relates to the technical field of building construction, in particular to a drainage construction method for a foundation pit of a high-water-level fan foundation in a desert sand-blown region. Background With the continuous advancement of national carbon peak and carbon neutralization work, the wind power industry is becoming a green-powered core engine, strategically becoming increasingly prominent, and becoming a global energy conversion core support. Under the guidance of the 'double carbon' target, the wind power industry in China continuously and rapidly develops, and fans are widely distributed in mountain, plain, plateau, gobi, offshore and desert and marginal areas. And along with the clear national emphasis of desert, gobi and desert areas, the construction of large-scale wind power bases is quickened, wind power generation engineering is continuously extending to the desert areas in the west and the north, and the environmental conditions of project construction are also more complicated and special. The foundation soil in the desert area is mostly sandy soil and silt, the saturation of the soil body can be greatly improved due to the underground high water level, the internal friction angle and cohesive force of the sandy soil are reduced, the bearing capacity of the foundation is reduced, and uneven sedimentation or integral sedimentation of a fan foundation can be possibly caused. And when the construction site has the underground high water level condition, the foundation pit is easy to collapse under the high water level due to the characteristics of foundation soil, and the safety risk of the foundation pit is high. Therefore, how to avoid the adverse effect of the high water level and the precipitation condition on the construction process and the safety of the fan foundation becomes a key technical direction in the wind power generation project in the desert area. Disclosure of Invention The embodiment of the application aims to provide a drainage construction method for a high-water-level fan foundation pit in a desert sand-blown region, so that effective drainage of the foundation pit is realized in the construction process of the fan foundation pit, and the construction safety of the fan foundation pit in the high-water-level region is improved. The specific technical scheme is as follows: the embodiment of the application provides a drainage construction method for a foundation pit of a high-water-level fan foundation in a desert sand-blown region, which comprises the following steps: The method comprises the steps of forming a foundation pit by digging downwards a certain depth along an upper port line of the foundation pit in a selected foundation site, arranging an annular drainage ditch extending along an edge line of the bottom of the foundation pit at a preset distance from the slope toe of the foundation pit, arranging a plurality of water collecting wells uniformly distributed along the edge line of the bottom of the foundation pit and communicated with the annular drainage ditch, extracting and discharging accumulated water collected in the water collecting wells through drainage equipment until the groundwater level of the bottom of the foundation pit meets a preset dryness requirement, further digging downwards a certain depth on the basis of the current foundation pit, returning to the preset distance from the slope toe of the bottom of the foundation pit, arranging the annular drainage ditch extending along the edge line of the bottom of the foundation pit until the elevation of the bottom of the foundation pit reaches a design elevation, and constructing a fan foundation in the foundation pit under the condition that the elevation of the bottom of the foundation pit reaches the design elevation and the foundation pit passes through a test groove. Optionally, after the bottom elevation of the foundation pit is excavated downwards to reach the designed elevation, the drainage construction method for the high water level fan foundation pit in the desert sand region before the construction of the fan foundation is performed in the foundation pit further comprises the following steps: The bottom of the foundation pit is provided with a plurality of simple drainage ditches which extend from the center of the foundation pit to the edge of the foundation pit and are communicated with the annular drainage ditches at the bottom of the foundation pit, the bottom of the simple drainage ditches is provided with slopes, the height of the bottom of the simple drainage ditches gradually decreases along a first direction, and the first direction is the direction from the center of the foundation pit to the edge of the foundation pit. Optionally, set up many from the foundation ditch center to the foundation ditch edge extension in the foundation d