Deep foundation pit cast-in-situ bored pile enclosure invasion reinforcing treatment structure and method

Abstract

The invention relates to a deep foundation pit cast-in-situ bored pile enclosure invasion reinforcing treatment structure and method. The structure is characterized in that water stop high-pressure jet grouting piles are arranged on the outer sides of enclosure piles, supports are arranged on the upper portion and the lower portion of a invasion area, a bottom plate cushion layer and a hidden beam reinforcing structure are adopted, and an anchor rod reinforcing structure is adopted for a soil layer of the invasion area. The method comprises the following specific steps of: (1) additionally driving high-pressure jet grouting piles on the outer sides of the deviated row piles for reinforcement; (2) after the foundation pit is excavated to the elevation of an upper layer of support in a invasion area, the sectional dimensions of original concrete enclosing purlins and concrete angle braces are enhanced; (3) when a bearing platform falling pit is excavated, the boundary invasion row piles are chiseled away while excavation is carried out; (4) in the chiseling process, reinforcing the pile foundation in the chiseling area by adopting a soil anchor rod method; and (5) after excavating to the bottom of the bearing platform pit, reinforcing the cushion layer in the area, and additionally arranging a concrete waist beam. The method can be used for solving the situation that the enclosure structure is beyond the boundary due to various reasons in engineering, the potential safety hazard of the enclosure structure is greatly reduced, and the subsequent construction cost is reduced.

Description

Technical Field

[0001] The invention relates to a deep foundation pit bored cast-in-place pile, in particular to a deep foundation pit bored cast-in-place pile enclosure intrusion reinforcement treatment structure and method. Background Art

[0002] At present, many deep foundation pits under construction use bored cast-in-place piles plus internal support for foundation pit support. This form of support has high requirements for bored cast-in-place pile positioning, pile construction management, and operation level during construction. However, in the actual construction process, due to the influence of mechanical factors, geological factors, and human factors, there are often retaining piles invading the outer wall edge of the structure after the foundation pit is excavated. In addition, some projects are restricted by the construction site and the main structure is constructed close to the retaining piles. At this time, since the outer wall of the basement structure cannot be constructed, the retaining piles that intrude into the basement structure must be chiseled out to ensure the thickness and integrity of the basement structure floor, pedestal and side wall. However, this will greatly reduce the safety factor of the foundation pit retaining structure during construction. In severe cases, it will cause insufficient bending and shear bearing capacity at the weakened section of the pile foundation in the excavated area of ​​the foundation pit retaining, excessive deformation, and cracking, which will lead to major personnel and safety accidents. Therefore, the retaining piles that have been chiseled out and intruded must be handled. Summary of the invention

[0003] The purpose of the present invention is to provide a deep foundation pit bored cast-in-place pile retaining boundary reinforcement treatment structure and method based on the above-mentioned deficiencies in the prior art, in order to solve the problem that retaining piles often intrude into the outer wall edge of the structure after foundation pit excavation. In addition, some projects are restricted by the construction site and the main structure is constructed close to the retaining piles. At this time, the outer wall of the basement structure cannot be constructed. The structure and method can be used to solve the problem of retaining structure intrusion caused by various reasons in the project, greatly reduce the safety hazards of the retaining structure, and reduce the subsequent construction costs.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a deep foundation pit bored cast-in-place pile enclosure intrusion reinforcement treatment structure, including: water-stop high-pressure rotary jet piles are arranged on the outside of the enclosure piles, the upper and lower parts of the intrusion area are reinforced by supports, bottom plate cushion layers and hidden beams, and the soil layer in the intrusion area is reinforced by anchor rods.

[0005] A construction method for a deep foundation pit bored cast-in-place pile enclosure and reinforcement treatment structure, the specific steps are:

[0006] (2) High-pressure jet grouting piles are added to the outside of the offset piles for reinforcement;

[0007] (2) After the foundation pit is excavated to the upper support elevation of the intrusion zone, the cross-sectional dimensions of the original concrete purlins and concrete angle braces are strengthened;

[0008] (3) When excavating the deep pit for the foundation, the encroaching piles should be removed while digging;

[0009] (4) During the chiseling process, the soil anchor method is used to strengthen the pile foundation in the chiseling area;

[0010] (5) After excavation to the bottom of the foundation pit, the cushion layer in this area is strengthened, a concrete waist beam is added, and a concrete hidden beam is added inside the cushion layer. The concrete hidden beam is connected to the surrounding structure by planting reinforcement or welding, and a steel mesh is arranged in the cushion layer reinforcement area.

[0011] Furthermore, the reinforcement construction of high-pressure rotary jet piles on the outside of the offset pile row requires drilling holes, the pile diameter is 800mm, and the reinforcement range is from the top ring beam to 4m below the bottom of the pedestal.

[0012] Furthermore, the thickness of the original concrete angle brace of the upper support layer of the intrusion area shall be strengthened to no less than 300mm;

[0013] Furthermore, after excavation to the bottom of the pedestal pit, the cushion layer in this area is strengthened. The specific specifications are to add a 1000mm*800mm concrete waist beam and a 1000mm*800mm concrete hidden beam in the cushion layer. The hidden beam is connected to the surrounding structure by embedded reinforcement or welding, and a φ18@250 single-layer bidirectional steel mesh is arranged in the cushion layer reinforcement area.

[0014] Furthermore, the soil anchor method uses HRB335 grade φ15mm steel bars, which are arranged from the top of the pile removal area, with a vertical interval of 500mm, and are arranged parallel to each other. The anchor angle is 20°, and the channel steel is connected to the piles on both sides. The channel steel uses 10# channel steel. The anchor is inserted into the soil layer for not less than 6m. In order to ensure the bending resistance of the pile foundation in this area, the main reinforcement in the tension zone of the removed side piles needs to be retained.

[0015] The beneficial effects of the present invention are:

[0016] The present invention uses outer side water stopping, upper and lower supports in the area of ​​the excavated pile foundation and the support points of the hidden beam in the cushion layer, and combines a method of vertically arranging multiple soil layer anchors in the weak pile foundation section in the excavated area to strengthen the combined method of anchor reinforcement. In terms of structural stress, the vertical single-span simply supported bending in the area of ​​the excavated pile foundation is transformed into a continuous beam supported by vertical multi-span supports in the area of ​​the excavated pile foundation. Compared with the bending moment in the span of the original simply supported bending in the large-span area, the bending moment is greatly reduced, the weakened section after excavation can also meet the requirements, and the deformation of the pile foundation transformed from simply supported to multi-span continuous is also greatly reduced.

[0017] The present invention effectively handles the construction problem of safe backbuilding of the outer wall of the basement encroaching part of the structure, avoids the situation in which the enclosure structure encroaches on the boundary due to various reasons in the past, reduces safety hazards in subsequent construction, greatly improves construction efficiency, and reduces construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the plane layout of the reinforcement treatment of the enclosure intrusion;

[0019] Figure 2It is the elevation development drawing of the anchor rod;

[0020] Figure 3 It is a schematic diagram of the cross-sectional arrangement of anchor rods for reinforcement of the soil layer intruded by retaining piles;

[0021] Figure 4 This is a schematic diagram of retaining steel bars in retaining piles. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments of the Shanghai Pudong Airport foundation pit project. These embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. After reading the contents of the present invention, technicians in the relevant field can make various modifications or equivalent substitutions to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

[0023] like Figures 1 to 4 As shown, a deep foundation pit bored cast-in-place pile enclosure intrusion reinforcement treatment structure of the present invention comprises: a water-stop high-pressure rotary jet pile 2 is arranged on the outside of the enclosure pile, the upper and lower intrusion areas are reinforced by supports, bottom plate cushion layers and hidden beams, and the soil layer in the intrusion area is reinforced by anchor rods.

[0024] like Figures 1 to 4 As shown, the present invention is a construction method of a deep foundation pit bored cast-in-place pile enclosure intrusion reinforcement treatment structure, the specific steps are:

[0025] (1) High-pressure jet grouting piles 2 are added to the outside of the offset pile row 1 for reinforcement. The pile diameter is 800 mm. The reinforcement range is from the top ring beam to 4 m below the bottom of the cap. The top ring beam construction in this area is completed, and the reinforcement construction requires drilling.

[0026] (2) After the foundation pit is excavated to the general area floor elevation, the original 2000mm*2000mm*200mm concrete angle brace in this area is changed to 4000mm*4000mm*300mm concrete angle brace 5;

[0027] (3) When excavating the deep pit for the foundation, the encroaching piles should be removed while digging;

[0028] (4) During the chiseling process, the soil layer anchor method is used to strengthen this area. Anchor rods 3 are made of HRB335 grade φ15 steel bars, which are arranged from the top of the pile chiseling area, with a vertical interval of 500mm, and are arranged parallel to each other. Anchor rods 3 have an inclination of 20°. Channel steel 4 is connected to the offset piles 1 on both sides. Channel steel 4 is 10# channel steel, and anchor rods 3 are inserted into the soil layer for not less than 6m. Under the action of anchor rods 3, as the foundation pit is excavated and the offset chiseling side of the pile foundation is thrown under tension, in order to ensure the bending resistance of the pile foundation in this area, the main reinforcement steel bars 7 need to be retained in the tension area of ​​the piles on the chiseling side.

[0029] (5) After excavation to the bottom of the foundation pit, the cushion layer in this area is strengthened, and a 1000mm*800mm concrete waist beam is added. A 1000mm*800mm concrete hidden beam 8 is added in the cushion layer 6. The concrete hidden beam 8 is connected to the surrounding structure by planting or welding. A φ18@250 single-layer bidirectional steel mesh is arranged in the reinforced area of ​​the cushion layer 6.

Claims

1. A deep foundation pit bored cast-in-place pile enclosure intrusion reinforcement treatment structure, It is characterized in that include: Water-stop high-pressure rotary jet piles are set on the outside of the retaining piles, and the upper and lower parts of the intrusion zone are reinforced with supports, bottom plate cushions and hidden beams, and the soil layer in the intrusion zone is reinforced with anchor rods.

2. A construction method using the deep foundation pit bored cast-in-place pile enclosure and intrusion reinforcement treatment structure according to claim 1, It is characterized in that The specific steps are: (1) High-pressure jet grouting piles are added to the outside of the offset piles for reinforcement; (2) After the foundation pit is excavated to the upper support elevation of the intrusion zone, the cross-sectional dimensions of the original concrete purlins and concrete angle braces are strengthened; (3) When excavating the deep pit for the foundation, the encroaching piles should be removed while digging; (4) During the chiseling process, the soil anchor method is used to strengthen the pile foundation in the chiseling area; (5) After excavation to the bottom of the foundation pit, the cushion layer in this area is strengthened, a concrete waist beam is added, and a concrete hidden beam is added inside the cushion layer. The hidden beam is connected to the surrounding structure by embedding or welding, and a steel mesh is arranged in the cushion layer reinforcement area.

3. The construction method according to claim 2, Features: The reinforcement construction of high-pressure jet jet piles on the outside of the offset pile row requires drilling holes, the pile diameter is 800mm, and the reinforcement range is from the top ring beam to 4m below the bottom of the pedestal.

4. The construction method according to claim 2, Features: The thickness of the original concrete angle brace of the upper support layer in the intrusion area is strengthened to no less than 300mm.

5. The construction method according to claim 2, Features: After excavation to the bottom of the pedestal pit, the cushion layer in this area is strengthened. The specific specifications are to add a 1000mm*800mm concrete waist beam, and a 1000mm*800mm concrete hidden beam is added in the cushion layer. The mm hidden beam is connected to the surrounding structure by embedded reinforcement or welding, and a φ18@250 single-layer bidirectional steel mesh is arranged in the cushion layer reinforcement area.

6. The construction method according to claim 2, Features: The soil anchor method uses HRB335 grade φ15mm steel bars, which are arranged from the top of the pile removal area, with a vertical interval of 500mm, and are arranged parallel to each other. The anchor angle is 20°, and the channel steel is connected to the piles on both sides. The channel steel uses 10# channel steel. The anchor is inserted into the soil layer for not less than 6m. In order to ensure the bending resistance of the pile foundation in this area, the main reinforcement in the tension zone of the removed side piles needs to be retained.

Images