A convex foundation pit external corner supporting and reinforcing method

Abstract

The application discloses a convex foundation pit external corner supporting and reinforcing method, and the arrangement mode of the pile is that one plain concrete pile and one reinforced concrete pile are arranged at intervals to form a seamless continuous pile wall, a fixed pile is arranged at a position of 3-5 meters in a 45-degree internal corner of the external corner of the foundation pit, the fixed pile is connected with the pile wall through an anchor cable, and a corbel is arranged on the pile wall, so that the convex foundation pit external corner supporting and reinforcing method can effectively solve the stability control problem of the external corner of the foundation pit, can control the safety hidden trouble caused by the collapse of the foundation pit in the construction process, and is technically and economically feasible.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of foundation pit support construction technology, in particular to a convex foundation pit external corner support and reinforcement method. BACKGROUND

[0002] With the development of foundation pit engineering, the planar shape of the foundation pit is more and more irregular, and a large number of external corners appear in different situations. Due to the shape mutation and the increase of the free surface, the internal force of the soil body and the supporting structure at the external corner of the foundation pit is very complex, which is a stress concentration part. A large number of engineering practices show that the earth pressure and horizontal displacement within a certain range of the external corner of the foundation pit are greater than those in the middle of the foundation pit. The external corner of the foundation pit is an unfavorable position for deformation control, and the stability is poor, which is easy to cause excessive deformation or overall collapse, thereby causing serious impact on surrounding buildings.

[0003] The collapse of the external corner of the foundation pit has obvious continuous collapse characteristics, that is, first local instability, partial supporting structure failure, then continuous development of the damage, leading to local collapse, and finally overall collapse of the external corner.

[0004] At present, the external corner of the foundation pit mostly adopts the same supporting mode as the normal side wall of the foundation pit, and the supporting effect is not ideal. If reinforced support or special support mode is adopted at the external corner of the foundation pit, the supporting structure of the external corner of the foundation pit has sufficient redundancy, and when the foundation pit is locally unstable, the redundant load at the external corner can be transferred to other parts of the foundation pit, so that the excessive load at the external corner is borne by the whole supporting system. The foundation pit will not collapse in a large area, and will not have serious impact on surrounding buildings. Therefore, a new foundation pit external corner support technology measure needs to be invented to effectively control the stability of the external corner of the foundation pit. SUMMARY

[0005] The present application aims at the deficiencies in the prior art, and provides a convex foundation pit external corner support and reinforcement method. The present application can effectively solve the stability control problem of the external corner of the foundation pit, and can control the safety hazards caused by the collapse of the foundation pit during construction.

[0006] The present application is implemented by the following technical scheme: a convex foundation pit external corner support, the arrangement mode of the piles is that one plain concrete pile and one reinforced concrete pile are arranged at intervals to form a seamless continuous pile wall, a fixed pile is arranged at a position 3-5 meters from the internal corner of the external corner of the foundation pit within 45°, the fixed pile is connected with the pile wall through an anchor cable, and a corbel is arranged on the pile wall.

[0007] A reinforcement method for a convex foundation pit external corner support, comprising the following steps:

[0008] (1) Interlocking pile construction

[0009] The arrangement mode of the piles is that one plain concrete pile (A pile) and one reinforced concrete pile (B pile) are arranged at intervals, the A pile is constructed first and then the B pile is constructed, when the B pile is constructed, the concrete of the intersecting part of the adjacent A pile is cut off, the occlusion is realized, and the seamless continuous pile wall is formed;

[0010] (2) Fixed pile construction

[0011] One fixed pile is arranged at the position of 3-5 meters in the 45° internal angle of the foundation pit;

[0012] (3) Crown beam construction

[0013] The crown beam is arranged at the top of the pile wall, the center line, the side line and the elevation of the crown beam and the reinforced concrete support are determined through measurement and line laying, when the pile wall is formed, the crown beam construction is started, the first step is to dig a groove, chisel off the pile top floating slurry and support the mold; the second step is to bind the steel bars in the groove to form a shape, support the mold; the third step is to pour concrete and maintain the concrete;

[0014] (4) Anchor cable construction

[0015] After the concrete reaches the design strength of 75%, the pile wall and the fixed pile are connected through the anchor cable.

[0016] Preferably, the A pile adopts super slow setting concrete, and the construction of the B pile is completed before the A pile concrete initial setting.

[0017] Preferably, the B pile is C30 concrete; and the A pile is C25 concrete.

[0018] Preferably, the fixed pile is a C30 reinforced concrete pile with a diameter of 1000mm.

[0019] Preferably, the size of the crown beam is 1200*800mm.

[0020] Preferably, before the crown beam construction, the pile top floating slurry of the support pile should be cleaned completely, embedded into the crown beam by 50mm, the pile steel bars are anchored into the crown beam by greater than or equal to 35d, if there is still sediment after the pile head is chiseled, the sediment should be chiseled completely, and then the C30 concrete is poured and tamped to the bottom of the crown beam; the pile surface must be cleaned completely before the crown beam can be poured and tamped.

[0021] Preferably, the anchor cable is used to pull the B pile and the fixed pile once every five meters from the top of the pile to the bottom of the pile until the position of the pile bottom.

[0022] Preferably, the anchor cable adopts a single anchor cable with a diameter of 21.6mm, and the strength grade of the steel strand is 1860Mpa.

[0023] The beneficial effects of the present application are:

[0024] 1. The safety of the buildings, structures, pipes, lines and cables near the edge is ensured.

[0025] 2. During the excavation of the foundation pit and the use of the foundation pit, the free soil is maintained stable to ensure the safety of the construction. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0027] Figure 1 It is a construction flow chart of the full casing interlocking pile.

[0028] Figure 2 It is a construction flow chart of the rotary digging interlocking pile.

[0029] Figure 3 It is a pile position schematic diagram of the interlocking pile.

[0030] Figure 4 It is a whole schematic diagram of the foundation pit supporting and reinforcing method.

[0031] The meanings of the symbols in the figure are as follows:

[0032] 1-concrete pile, 2-plain concrete pile, 3-fixed pile, 4-crown beam, 5-anchor cable. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without any creative effort are within the protection scope of the present application.

[0034] The convex foundation pit external corner support of the present application is characterized in that: the arrangement mode of the pile is that one plain concrete pile 2 and one reinforced concrete pile 1 are arranged at intervals to form a seamless continuous pile wall, a fixed pile 3 is arranged at a position 3-5 meters from the internal corner 45° of the external corner of the foundation pit, the fixed pile 3 is connected with the pile wall through an anchor cable 5, and a crown beam 4 is arranged on the pile wall.

[0035] The reinforcing method of the convex foundation pit external corner support of the present application comprises the following steps:

[0036] Firstly, as shown in the flow chart, the interlocking pile is constructed. Figure 1 Figure 2

[0037] (1) Full casing interlocking pile construction

[0038] ​​A kind of foundation pit enclosure structure that pile and pile are arranged mutually interlocked, adopt casing drill rig to drill hole, mainly adopt " casing drill rig + super slow setting concrete " scheme in construction.The arrangement of pile is that one plain concrete pile (A pile) and one reinforced concrete pile (B pile) are arranged at intervals, A pile is constructed first and then B pile is constructed in construction, A pile adopts super slow setting concrete, it must be required to complete the construction of B pile before A pile concrete initial setting.B pile is constructed, the concrete of the intersection part of adjacent A pile is cut off, interlocking is realized, and seamless continuous " pile wall " is formed.

[0039] It includes the following construction procedures: construction preparation, pile site measurement and setting-out, guide wall construction, casing drill rig positioning and centering, hoisting the first section of casing, perpendicularity measurement and control, pressing the first section of casing for perpendicularity correction, grab bucket soil removal→soil removal for external transportation, pressing the second···N section of casing for grab bucket soil removal to the design elevation→soil removal for external transportation, steel reinforcement cage processing and manufacturing→hoisting the B pile steel reinforcement cage, guide pipe installation, commercial concrete mixing and transportation→concrete pouring→test piece reservation, pipe pulling for pile formation and machine moving, next cycle construction.

[0040] (2) Rotary interlocked pile construction

[0041] A kind of foundation pit enclosure structure that pile and pile are arranged mutually interlocked, adopt rotary drilling rig to drill hole.The arrangement of pile is that one plain concrete pile (A pile) and one reinforced concrete pile (B pile) are arranged at intervals, A pile is constructed first and then B pile is constructed in construction, after the construction of adjacent multiple A piles, B pile is constructed, B pile is constructed, the concrete of the intersection part of adjacent A pile is cut off, interlocking is realized, and seamless continuous " pile wall " is formed.

[0042] It includes the following construction procedures: construction preparation, pile site measurement and setting-out, guide wall construction, steel casing manufacturing→steel casing embedding, drill rig positioning, mud mixing and storage→drilling for hole formation, first hole cleaning, final hole acceptance, steel reinforcement cage processing and manufacturing→hoisting the B pile steel reinforcement cage, guide pipe trial assembly and water tightness test→guide pipe installation, second hole cleaning, commercial concrete mixing and transportation→concrete pouring→test piece reservation, pile formation and machine moving, next cycle construction.

[0043] Among them, the concrete grade of the A pile of the interlocked pile is C30 concrete;the concrete grade of the plain pile is C25 concrete.

[0044] The second step, as shown in Figure 3 A C30 reinforced concrete pile with a diameter of 1000 mm is set at a position 3-5 meters from the inner 45° corner of the foundation pit.

[0045] Third step, the support pile top sets up 1200*800mm crown beam, through the measurement of the line, the center line, the side line and the elevation of the crown beam and the reinforced concrete support are determined. Before the construction of the crown beam, the float slurry on the top of the support pile should be cleaned, embedded into the crown beam by 50mm, and the pile steel is anchored into the crown beam by ≥35d. If there is still sediment after the pile head is chiseled, it should be chiseled completely, and then poured and tamped with C30 concrete to the bottom of the crown beam; the pile surface must be cleaned before pouring and tamping the crown beam. After the support wall is formed into a pile, the crown beam construction is started, the first step: dig the trench, chisel the float slurry on the top of the pile, and support the mold; the second step: bind and shape the steel bars in the trench, and support the mold; the third step: pour concrete, and maintain the concrete.

[0046] Fourth step, after the concrete reaches 75% of the design strength, the department with the foundation pile detection qualification is entrusted to detect the quality of the formed pile. After the detection is passed, the anchor cable is subjected to the construction of the opposite pull.

[0047] The anchor cable is subjected to the construction of the opposite pull every five meters from the top of the pile to the bottom of the pile, three B piles in the center and fixed piles are subjected to the opposite pull through the anchor cable until the position of the bottom of the pile.

[0048] The above-described embodiments are only used to describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art should fall within the protection scope of the present application.

Claims

1. A reinforcement method for the external corner support of a convex foundation pit, characterized in that, The piles are arranged with one plain concrete pile and one reinforced concrete pile alternately to form a seamless and continuous pile wall. Fixed piles are set at the 45° inner angle of the foundation pit, 3-5 meters away. The fixed piles are connected to the pile wall by anchor cables. A capping beam is set on the pile wall. The reinforcement method includes the following steps: (1) Construction of interlocking piles The piles are arranged in a way that alternates between one plain concrete pile, called pile A, and one reinforced concrete pile, called pile B. During construction, pile A is constructed first, followed by pile B. When constructing pile B, the concrete at the intersection of adjacent pile A is cut off to achieve interlocking and form a seamless and continuous pile wall. (2) Construction of fixed piles A fixed pile is driven 3-5 meters at the 45° inner corner of the foundation pit; (3) Construction of the cap beam A capping beam is installed on top of the pile wall. The center line, edge line and elevation of the capping beam and reinforced concrete support are determined by measurement and layout. After the retaining wall is piled, the capping beam construction begins. The first step is to excavate the trench, remove the laitance on the pile top and set up the formwork; the second step is to tie the reinforcing steel bars in the trench and set up the formwork; the third step is to pour concrete and cure the concrete. Before constructing the capping beam, the laitance on the top of the support piles should be cleaned and embedded 50mm into the capping beam. The pile reinforcement should be anchored into the capping beam for ≥35d. If there is still sediment after chiseling the pile head, it should be completely removed. Then, C30 concrete should be poured up to the bottom of the capping beam. The pile surface must be cleaned before the capping beam can be poured. (4) Anchor cable construction After the concrete reaches 75% of its design strength, the pile wall is connected to the fixed pile using anchor cables. The anchor cables are used to pull the B pile and the fixed pile together every five meters from the top of the pile to the bottom of the pile, until the bottom of the pile is reached. The A pile is made of ultra-slow setting concrete, and the construction of the B pile is completed before the A pile concrete initially sets; The B piles are made of C30 concrete; the A piles are made of C25 concrete. The fixed pile is a C30 reinforced concrete pile with a diameter of 1000mm; The dimensions of the crown beam are 1200*800mm; The anchor cable has a single anchor cable diameter of 21.6 mm and a steel strand strength level of 1860 MPa.

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