Foundation pit guard method for expansion construction from deep foundation pit to shallow foundation pit

Abstract

The invention relates to a foundation ditch enclosure protection method for the expanding construction from a deep foundation ditch to a shallow foundation ditch caused by the changing of a building structure function which includes the following steps: (1) arranging a bore grouting pile at the boundary of the deep and the shallow foundation ditch by utilizing the gap besides a cushion cap and arranging a waterproof curtain for cement stirring at the outer side; (2) excavating the earthwork of the shallow foundation ditch, constructing a bottom board structure, carrying out anchor-pulling by taking the bottom board of the shallow foundation ditch to form an integral rigidness by connecting a coping with the enclosure protection of the deep foundation ditch; (3) the earthwork of the deep foundation ditch when the intensity of the bottom board of the shallow foundation ditch in the excavating area of the deep foundation ditch reaches 90 percent, the intensity of the neighboring bottom board reaches 70 percent and the intensity of the bore grouting pile reaches 100 percent; (4) constructing a deep foundation structure. The construction method of the invention can be adopted to carry out foundation ditch enclosure protection and has the advantages of fast construction speed and good enclosure protection effect, etc.

Description

technical field [0001] The invention relates to a foundation pit enclosure method in the field of construction, in particular to a foundation pit enclosure method based on the original foundation pit enclosure, which needs to be expanded from deep foundation pits to shallow foundation pits due to changes in building structure functions. Background technique [0002] During the construction process, the original underground foundation is often changed due to the adjustment of the function of the underground structure. On the basis of the underground structure, the axis of the underground structure, the pile foundation of the cap, the deep foundation pit and the shallow foundation pit are protected. There are three traditional methods of protection: 1) The shaft is surrounded by a mixing pile gravity dam. The pile foundations of the caps are powder-sprayed piles. The disadvantages of this enclosure method are: ①The construction of powder-sprayed piles and mixing piles will squ...

AI Technical Summary

Problems solved by technology

[0002] During the construction process, the original underground foundation is often changed due to the adjustment of the function of the underground structure. On the basis of the underground structure, the axis of the underground structure, the pile foundation of the cap, the deep foundation pit and the shallow foundation pit are protected. There are three traditional methods of protection: 1) The shaft is surrounded by a mixing pile gravity dam. The pile foundations of the caps are powder-sprayed piles. The disadvantages of this method of enclosure are: ①The construction of powder-sprayed piles and mixing piles will squeeze the pile foundations, and the pile foundations are not easy to be effectively protected; ②Due to the existence of two kinds of enclosures For the pile body, there are many construction overlaps, so it is not easy to ensure the overall quality of the enclosure; ③The cost of powder sprayed piles is relatively high, which is not conducive to the control of enclosure costs

2) The bearing platform falls deep and is wrapped in the deep foundation. A cement mixing pile gravity dam is installed on one side of the platform. The disadvantages of this enclosure method are: ①The bearing platform is lowered, the pile foundation is shortened, and the original design is changed. It needs to be confirmed by the structural design; ②The workload of excavation and filling is increased, and the quality of backfill soil is difficult to control after the caps fall deep

3) Deep and shallow foundations are protected by soil-nailed walls. The disadvantages of this type of enclosure are: ① Due to the use of cement-mixed piles combined with soil-nailed walls, the cement-mixed piles have a certain maintenance period, and the construction period is relatively long; ② Soil The process of nailing wall construction and earthwork excavation requires high overlap; ③Construction in the specific sandy soil layer of the airport, similar practical experience is relatively small, and there are certain risks

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