阅读说明：本技术 一种高水位深基坑开挖施工方法 (High-water-level deep foundation pit excavation construction method ) 是由 罗天洪 冯学瑞 晏克珍 谢明康 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种高水位深基坑开挖施工方法,该方法首先进行基坑支护施工,然后对基坑内的土方进行分层开挖；当土方开挖至基底上方5米时进行工程桩施工,并保留基底上方的5米土方；当工程桩施工完成后,对基坑内的土方进行二次开挖,直至土方开挖至基底,然后立即浇筑底板垫层并进行主体机构施工。本发明采用土方开挖至基底5米时插入工程的施工方式,可以有效节约工期,同时基坑脚受到5米土方的制约,基坑变形可控；同时由于工程桩距离支护桩较近,提早插入工程桩施工对基坑支护形成基底加固,确保基坑及周边环境安全,节约施工成本、缩短施工工期。(The invention discloses a high water level deep foundation pit excavation construction method, which comprises the steps of firstly carrying out foundation pit supporting construction, and then carrying out layered excavation on earthwork in a foundation pit; when the earthwork is excavated to 5 meters above the substrate, construction of an engineering pile is carried out, and 5 meters of earthwork above the substrate is reserved; and after the construction of the engineering pile is finished, performing secondary excavation on earthwork in the foundation pit until the earthwork is excavated to the substrate, and then immediately pouring a bottom plate cushion layer and performing main mechanism construction. The construction method of inserting the engineering when the earthwork is excavated to 5 meters from the base is adopted, so that the construction period can be effectively saved, and meanwhile, the foundation pit foot is limited by the earthwork of 5 meters, so that the foundation pit deformation can be controlled; meanwhile, the engineering pile is close to the supporting pile, so that the foundation pit is supported by inserting the engineering pile in advance for construction to form foundation reinforcement, the safety of the foundation pit and the surrounding environment is ensured, the construction cost is saved, and the construction period is shortened.)

1. A construction method for excavating a deep foundation pit at a high water level is characterized by comprising the following steps:

s1, firstly, carrying out foundation pit supporting construction, and then carrying out layered excavation on earthwork in the foundation pit;

s2, when the earthwork is excavated to 5 meters above the substrate, carrying out construction of the engineering pile, and keeping the 5 meters earthwork above the substrate;

and S3, after the construction of the engineering pile is completed, performing secondary excavation on earthwork in the foundation pit until the earthwork is excavated to the substrate, and then immediately pouring a bottom plate cushion layer and performing main body mechanism construction.

2. The high water level deep foundation pit excavation construction method according to claim 1, characterized in that: the foundation pit support adopts two support forms of a double-row cantilever pile or a single-row cantilever pile combined anchor cable structure.

3. The high water level deep foundation pit excavation construction method according to claim 1, characterized in that: and when secondary excavation is carried out on the earthwork, the earthwork is excavated by adopting a skip method.

Technical Field

The invention relates to a high water level deep foundation pit excavation construction method, and belongs to the technical field of foundation pit construction.

Background

The foundation pit supporting technology and the upper excavation technology are key technologies commonly used in building engineering, with the increase of large high-rise buildings, oversized and ultra-deep foundation pits are more and more, the maximum depth can reach about 60 meters, the foundation pit supporting to the extent needs professional and scientific foundation pit supporting technology to realize, and after the foundation pit supporting reaches the standard, foundation pit excavation operation is carried out, wherein the foundation pit supporting technology is applied to the earthwork excavation technology.

The method comprises the steps of fully analyzing conditions of a construction site before foundation pit construction, designing countermeasures for various influence factors to guarantee smooth construction, formulating a construction scheme according to actual conditions, starting excavation work above a first layer after construction of an engineering pile is finished, firstly carrying out precipitation work before earthwork excavation, enabling precipitation ranges to be a deep well, a foundation pit enclosure plane and an open trench, starting a water pumping test for deep well precipitation in two weeks before construction, and then changing and adjusting the scheme by combining actual engineering conditions and practical water pumping conditions, so that the construction quality of foundation pit precipitation engineering is guaranteed.

The supporting of foundation ditch is firm inadequately among traditional high water level deep basal pit excavation process, has certain safe risk, and the input of turnover materials such as template, steel pipe is more simultaneously, and the cost is higher.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the high-water-level deep foundation pit excavation construction method which can reduce the foundation pit construction risk, save the construction cost and shorten the construction period, so as to overcome the defects in the prior art.

The technical scheme of the invention is realized as follows: a construction method for excavating a deep foundation pit at a high water level comprises the following steps:

s1, firstly, carrying out foundation pit supporting construction, and then carrying out layered excavation on earthwork in the foundation pit;

s2, when the earthwork is excavated to 5 meters above the substrate, carrying out construction of the engineering pile, and keeping the 5 meters earthwork above the substrate; the foundation pit foot is restricted by earthwork 5 m above the foundation pit, so that the deformation of the foundation pit is controllable, and meanwhile, because the engineering pile is close to the support pile, the engineering pile is inserted in advance for construction and concrete is poured to support the foundation pit to form foundation reinforcement, so that the safety of the foundation pit and the surrounding environment is ensured;

and S3, after the construction of the engineering pile is completed, performing secondary excavation on earthwork in the foundation pit until the earthwork is excavated to the substrate, and then immediately pouring a bottom plate cushion layer and performing main body mechanism construction.

In the method, the foundation pit support adopts two support forms of a double-row cantilever pile or a single-row cantilever pile combined anchor cable structure.

In the method, when the earthwork is dug for the second time, the earthwork is dug by adopting a skip method.

Due to the adoption of the technical scheme, the invention has the advantages that: the construction method of inserting the engineering when the earthwork is excavated to 5 meters from the base is adopted, so that the construction period can be effectively saved, and meanwhile, the foundation pit foot is limited by the earthwork of 5 meters, so that the foundation pit deformation can be controlled; meanwhile, the engineering pile is close to the supporting pile, so that the foundation pit is supported by inserting the engineering pile in advance for construction to form foundation reinforcement, and the safety of the foundation pit and the surrounding environment is ensured. Meanwhile, the earthwork forms stress restraint on the foundation pit in a mode of not excavating to the base, the constructed engineering pile plays a role in solidifying and reinforcing foundation soil after pouring concrete, and then the area where the engineering pile is constructed preferentially jumps according to the analysis of the foundation pit stress to construct the area with better stress and lower risk, so that the foundation pit is gradually formed, the earthwork is excavated to a high-risk point step by step to quickly construct a main body structure, the exposure time of the foundation pit and the input of turnover materials (steel pipes, templates and the like) are reduced, the safety risk of the foundation pit is reduced, the construction cost is saved, and the construction period is shortened.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to the embodiment of the invention, the excavation depth of a foundation pit is 9-15 meters, the perimeter of the foundation pit is about 650m and irregular, the distance between the north and the adjacent municipal roads is 1-4m, a single-row pile and anchor rope supporting mode is adopted, 1-8 old residential buildings are removed from 1-2.5 m of the foundation pit on the north, the foundation is a strip-shaped shallow foundation, a double-row cantilever supporting mode is adopted, the peripheral pipelines are more, the ground rock layers are mainly formed by newly-accumulated artificial filling soil (Q4ml) miscellaneous filling soil, gravel sand and silty clay of a fourth system updating system stratum (Qpal), the underlying rock is argillaceous silty sandstone of a third system (N), the top-down distribution time is ① miscellaneous filling soil, the layer thickness is 0.50-6.40 m, the average thickness is 2.41m, the level elevation is 66.10-71.94 m, the bottom layer 63.00-71.24 m, the underground water level is ②, the ground water level is 0.60-60.60 m, the average water level elevation, the water level elevation of the ground water level of the ground sand is 2.7.84, the ground water level of the ground water level, the ground water level is 2.7.7-60 soil, the ground water level of the ground soil is formed by the ground water level, the ground water level of.

According to the general engineering outline, the high water level deep foundation pit excavation construction method is adopted for excavation, and the specific construction steps are as follows:

s1, firstly, carrying out foundation pit supporting construction, wherein the foundation pit supporting construction adopts two supporting forms of double-row cantilever piles or single-row cantilever piles combined with anchor cable structures, moving a high-pressure jet grouting pile waterproof curtain between supporting piles to the outer sides of the piles for construction, so that a waterproof barrier is formed inside and outside the foundation pit, the influence of construction disturbance and water level reduction on the surrounding environment is reduced, then carrying out layered excavation on earthwork in the foundation pit, and clearing away the excavated miscellaneous filling soil ① and gravel layer ②;

s2, when earthwork is excavated to the silty clay layer ③ and is 5 m away from the upper part of the substrate, construction of an engineering pile is carried out, and 5 m earthwork above the substrate is reserved;

and S3, after the construction of the engineering pile is completed, performing secondary excavation on earthwork in the foundation pit until the earthwork is excavated to the substrate, and then immediately pouring a bottom plate cushion layer and performing main body mechanism construction. And when secondary excavation is carried out on the earthwork, the earthwork is excavated by adopting a skip method. According to the method, the earthwork excavation is performed by a bin jump method, the earthwork of a weak point and a high-risk point is subjected to remaining later-stage construction according to the stress condition analysis of a foundation pit, and the earthwork is subjected to remaining earthwork excavation construction only after the base plates of other areas are constructed and stress transmission is formed on the foundation pit support, so that the exposure time of the foundation pit excavation is reduced, the safety risk is reduced, and the investment of turnover materials such as a template and a steel pipe is reduced.

In conclusion, the construction mode of inserting the engineering when the earthwork is excavated to the basement by 5 meters is adopted, so that the construction period can be effectively saved, and meanwhile, the foundation pit foot is limited by the earthwork of 5 meters, so that the foundation pit deformation is controllable; meanwhile, the engineering pile is close to the supporting pile, so that the foundation pit is supported by inserting the engineering pile in advance for construction to form foundation reinforcement, and the safety of the foundation pit and the surrounding environment is ensured. Meanwhile, the earthwork forms stress restraint on the foundation pit in a mode of not excavating to the base, the constructed engineering pile plays a role in solidifying and reinforcing foundation soil after pouring concrete, and then the area where the engineering pile is constructed preferentially jumps according to the analysis of the foundation pit stress to construct the area with better stress and lower risk, so that the foundation pit is gradually formed, the earthwork is excavated to a high-risk point step by step to quickly construct a main body structure, the exposure time of the foundation pit and the input of turnover materials (steel pipes, templates and the like) are reduced, the safety risk of the foundation pit is reduced, the construction cost is saved, and the construction period is shortened.