Foundation pit supporting construction method based on secant pile structure

Abstract

The invention belongs to the technical field of building construction methods, and particularly relates to a foundation pit supporting construction method based on a secant pile structure. The method sequentially comprises the steps of foundation pit bottom face grooving, reinforced concrete pile pouring, reinforced concrete pile primary curing, plain concrete pile positioning, secant pile overall curing and secant pile curing forming, and therefore the reinforced concrete piles and the plain concrete piles are formed in sequence in a direct contact mode; it is guaranteed that the width of gaps between piles in the secant piles is as small as possible, the overall stability of the secant pile structure is better, and the silt blocking effect is more comprehensive; and 2, the reinforcement cage is kept at a relatively central stable position in the reinforced concrete pile, so that the structural strength of the reinforced concrete pile is further improved, and the secant pile structure can resist larger foundation pit side wall deformation and collapse impact force.

Description

Technical Field

[0001] The present invention belongs to the technical field of building construction methods, and particularly relates to a foundation pit support construction method based on a secant pile structure. Background Art

[0002] A secant pile refers to a row of piles structure in which reinforced concrete piles and plain concrete piles are arranged at intervals. Specifically, the reinforced concrete pile includes a steel reinforcement cage, and its cross-sectional shape is a complete circle. The plain concrete pile does not have a steel reinforcement cage, and its cross-sectional shape is a partial circle with arc-shaped notches on both sides.

[0003] Among them, the two arc-shaped notches respectively clamp the two adjacent reinforced concrete piles on the left and right, making the entire row of piles have the effect of "combining the parts into a whole". The above-mentioned clamping structural relationship is the origin of the name "secant".

[0004] On the other hand, one of the main functions of secant piles is to support the foundation pit. For example, the Chinese utility model patent with the patent publication number CN218204337U and the publication date of January 3, 2023 discloses a secant pile structure for foundation engineering, including a first plain concrete pile. A first reinforced concrete pile is fixedly arranged on one side of the first plain concrete pile. The first plain concrete pile and the first reinforced concrete pile partially overlap, and a guide wall is fixedly arranged on one side of the first plain concrete pile.

[0005] The secant pile structure in this utility model patent has a good effect of retaining soil and preventing side leakage. However, in the actual process of high-strength support use, there are still many deficiencies. The most prominent one is that the gap between the plain concrete pile and the reinforced concrete pile is too large, resulting in: 1. A small amount of water and sediment continuously leak at this gap, and the cleanliness of the foundation pit environment is poor; 2. The large gap size causes a lag in the overall linkage effect of the secant support, which will further reduce the stability of the secant pile for foundation pit support.

[0006] In addition, in order to improve the curing structure strength of the concrete part in the secant pile, it is now necessary to improve the construction method of the secant pile. For example, the Chinese invention patent with the patent publication number CN114182727A and the publication date of March 15, 2022 discloses a secant pile construction method, including the following steps: placing a casing at a preset position, driving the casing to press down, and removing the sundries in the casing; when the casing encounters an obstacle during pressing down, clearing the obstacle at the lower end of the casing.

[0007] The secant pile construction method in this invention patent can make the final concrete pile have a complete curing structure and is not easily doped by "purifying" the environment inside the casing. However, if only the sundries in the pipe are removed, the structural strength of the reinforced concrete pile cannot be significantly improved.

[0008] Therefore, in summary, there is an urgent need for a complete implementation plan for the overall improvement of the interlocking pile structure and the interlocking pile construction method to ensure that the interlocking pile facilities in the foundation pit support operation can provide long-term and stable support and protection for the side soil layers. Summary of the invention

[0009] The present invention provides a foundation pit support construction method based on an interlocking pile structure, the method sequentially comprising grooving the bottom surface of the foundation pit, casting reinforced concrete piles, initial solidification of the reinforced concrete piles, positioning of plain concrete piles, overall solidification of the interlocking piles, and curing and molding of the interlocking piles, so that: 1. The reinforced concrete piles and the plain concrete piles are molded successively and in direct contact, so that the width of the gap between the piles inside the interlocking piles is as small as possible, the overall stability of the interlocking pile structure is better, and the mud and sand blocking effect is more comprehensive; 2. The steel cage maintains a relatively central and stable position inside the reinforced concrete pile, so that the structural strength of the reinforced concrete pile is further improved, and it is ensured that the interlocking pile structure can resist greater deformation of the foundation pit side wall and collapse impact.

[0010] The technical solution adopted by the present invention to solve the above problem is: a foundation pit support construction method based on an interlocking pile structure, which comprises the following steps in sequence: S1. Grooving on the bottom surface of the foundation pit: a combined groove unit for fixing and installing the steel cage, steel pipe and arc plate unit is opened on the bottom surface of the foundation pit; S2, pouring reinforced concrete piles: inserting and installing the steel cage and steel pipe on the combined slot unit, and then pouring concrete until the amount of concrete in the steel pipe reaches a preset height; S3, initial solidification of reinforced concrete pile: after all the concrete in the steel pipe is poured, let it stand for 2-5 hours to obtain a semi-solidified reinforced concrete pile, and then pull it up to remove the steel pipe; S4, positioning of plain concrete piles: inserting and installing the arc plate unit on the combination slot unit between two adjacent semi-solidified reinforced concrete piles, and installing a top combination frame unit on the arc plate unit and the semi-solidified reinforced concrete piles; S5, overall solidification of the interlocking pile: suspending and correcting the position of the steel cage on the top assembly frame unit, pouring concrete into the paired arc plate units until the amount of concrete in the arc plate units reaches the preset height of the plain concrete pile; S6. Curing and forming of interlocking piles: After all the concrete in the arc plate unit is poured, let it stand for 10-12 hours, then remove the arc plate unit and the top assembly frame unit, and then let it stand for 1-2 days to obtain the final interlocking pile structure for foundation pit support.

[0011] A further preferred technical solution lies in that: in S1, the structure of the combined groove unit includes an outer rectangular groove arranged on the bottom surface of the foundation pit, a circular inner groove arranged in the outer rectangular groove and used for inserting and installing the steel reinforcement cage, an annular outer groove arranged in the outer rectangular groove and used for inserting and installing the steel pipe, and a vertical groove arranged in the annular outer groove and used for plugging and installing the arc plate unit.

[0012] A further preferred technical solution lies in that: there are 4 vertical grooves provided on a single annular outer groove.

[0013] A further preferred technical solution lies in that: in S4, the structure of the arc plate unit includes an arc-shaped vertical plate with a sector-annular cross-sectional shape, a lower fixing column arranged on the lower surface of the arc-shaped vertical plate and used for plugging into the vertical groove, and an upper reinforcing groove arranged on the upper surface of the arc-shaped vertical plate and used for plugging into the top combined frame unit.

[0014] A further preferred technical solution lies in that: both end faces of the arc-shaped vertical plate are also arc-shaped surfaces.

[0015] A further preferred technical solution lies in that: in S4, the structure of the top combined frame unit includes a circular ring arranged above the steel pipe and used for connecting and reinforcing 4 arc-shaped vertical plates, a protruding column arranged on the lower surface of the circular ring and used for plugging into the upper reinforcing groove, a radial rod arranged on the circular ring, and a hook arranged on the radial rod and used for suspending and correcting the position of the steel reinforcement cage.

[0016] A further preferred technical solution lies in that: the top combined frame unit further includes an annular groove arranged on the inner ring surface of the circular ring and used for plugging the radial rod, and a sliding ring arranged on the radial rod and used for installing the hook.

[0017] A further preferred technical solution lies in that: in S5, the type of concrete poured into the arc plate unit is super-retarding concrete.

[0018] A further preferred technical solution lies in that: in S6, the width range of the gap between the reinforced concrete pile and the plain concrete pile in the secant pile structure is 0.5 - 1.2 cm.

[0019] A further preferred technical solution lies in that: after the top combined frame unit is removed in S6, the upper end surface of the reinforced concrete pile is leveled with concrete, and after the upper end surface leveling operation, the concrete base is poured inside the groove and outside the pile of the combined groove unit. Description of the Drawings

[0020] Figure 1 It is a flowchart of the steps of the present invention.

[0021] Figure 2 This is a schematic diagram of the position structure of the combined groove unit in the present invention.

[0022] Figure 3 This is a schematic diagram of the position of the vertical groove in the present invention from a top-down perspective.

[0023] Figure 4 This is a schematic diagram of the structure of the arc plate unit in the present invention.

[0024] Figure 5 This is a schematic diagram of the structure of the top combined rack unit in the present invention from a top-down perspective.

[0025] Figure 6 This is a schematic diagram of the position and shape of the sliding ring in the present invention.

[0026] Figure 7 This is a schematic diagram of the position and shape of the gap in the present invention.

[0027] Figure 8 This is a schematic diagram of the operation of pulling out and removing the steel pipe in the present invention.

[0028] In the figure, the meanings of the various marks are as follows: The bottom surface of the foundation pit a, the gap b, the road surface c, the reinforced concrete pile d, the plain concrete pile e, the leveling block f, the concrete base g; The steel reinforcement cage 1, the steel pipe 2, the arc plate unit 3, the combined groove unit 4, the top combined rack unit 5; The outer rectangular groove 401, the circular inner groove 402, the annular outer groove 403, the vertical groove 404, the arc-shaped vertical plate 301, the end face 301a, the lower fixing column 302, the upper reinforcement groove 303, the circular ring 501, the protruding column 502, the radial rod 503, the hook 504, the annular groove 505, the sliding ring 506. Specific embodiments

[0029] The following is only a preferred embodiment of the present invention, and does not limit the scope of the present invention.

[0030] As shown in the appendix Figure 1-8 A foundation pit support construction method based on a secant pile structure sequentially includes the following steps: S1. Grooving at the bottom surface of the foundation pit: A combined groove unit 4 for fixedly installing the steel reinforcement cage 1, the steel pipe 2, and the arc plate unit 3 is opened on the bottom surface a of the foundation pit. S2. Pouring the reinforced concrete pile: The steel reinforcement cage 1 and the steel pipe 2 are inserted and installed on the combined groove unit 4, and then concrete is poured until the amount of concrete in the steel pipe 2 reaches a preset height. S3, initial solidification of reinforced concrete pile: After all the concrete in the steel pipe 2 is poured, let it stand for 2-5 hours to obtain a semi-solidified reinforced concrete pile, and then pull it up to remove the steel pipe 2; S4, positioning of plain concrete piles: inserting and installing the arc plate unit 3 on the combination slot unit 4 between two adjacent semi-solidified reinforced concrete piles, and installing the top combination frame unit 5 on the arc plate unit 3 and the semi-solidified reinforced concrete piles; S5, solidification of the interlocking pile as a whole: suspending and correcting the position of the steel cage 1 on the top assembly frame unit 5, pouring concrete into the paired arc plate units 3 until the amount of concrete in the arc plate units 3 reaches the preset height of the plain concrete pile; S6. Curing and forming of interlocking piles: After all the concrete in the arc plate unit 3 is poured, let it stand for 10-12 hours, then remove the arc plate unit 3 and the top assembly frame unit 5, and then let it stand for 1-2 days to obtain the final interlocking pile structure for foundation pit support.

[0031] In this embodiment, the consumables of the construction method are: concrete and steel cage 1, and the auxiliary tools of the construction method are: steel pipe 2, arc plate unit 3 and top assembly frame unit 5.

[0032] Among them, although the plain concrete pile e is cast directly on the reinforced concrete pile d, the casting order of the two is different and the types of concrete materials are also different, so a gap b can be formed which is indispensable for the interlocking pile structure but cannot be too wide.

[0033] In the prior art, the gap of the interlocking pile mainly comes from the thickness of the steel pipe itself. At this time, the width of the gap can reach 2-4 cm. This size is relatively large, which not only reduces the stability of the interlocking structure between the plain concrete pile and the reinforced concrete pile, but also allows a large amount of mud and sand to leak through.

[0034] In addition, the functions of the arc plate unit 3 are: 1. The two sides of the single plate body are directly attached to the reinforced concrete piles d; 2. The space between the paired plates is used to cast and form the plain concrete piles e, so that the two concrete piles are directly contacted and formed, that is, the gap b is not generated by the thickness of the spacer material, but by the inevitable shrinkage of the concrete material itself, so as to ensure that the gap b is thin enough.

[0035] The combined slot unit 4 is used to fully and stably fix the steel cage 1, the steel pipe 2 and the arc plate unit 3 in advance, ensuring that the three can be vertically installed and ready for use.

[0036] Finally, the top assembly rack unit 5 has at least two functions: 1. Reinforce the paired arc plate units 3, and a single top combined frame unit 5 can reinforce 2 pairs of the arc plate units 3 at one time; 2. During the curing process of the reinforced concrete pile d, the top combined frame unit 5 can suspend and correct the position of the steel reinforcement cage 1 so that the steel reinforcement cage 1 is finally located at the exact center of the reinforced concrete pile d. Otherwise, the structural stability and support strength of the reinforced concrete pile d will be greatly reduced.

[0037] In addition, when the top combined frame unit 5 is in use, the steel pipe 2 has been removed. At this time, the arc plate unit 3 becomes the installation position of the top combined frame unit 5, that is, the support and force application position where the top combined frame unit 5 suspends the steel reinforcement cage 1.

[0038] Therefore, the reaction force of the suspension action on the top combined frame unit 5 can further reinforce the vertically and paired installed arc plate units 3.

[0039] In S1, the structure of the combined groove unit 4 includes an outer rectangular groove 401 provided on the bottom surface a of the foundation pit, a circular inner groove 402 provided in the outer rectangular groove 401 and used for inserting and installing the steel reinforcement cage 1, an annular outer groove 403 provided in the outer rectangular groove 401 and used for inserting and installing the steel pipe 2, and a vertical groove 404 provided in the annular outer groove 403 and used for plugging and installing the arc plate unit 3.

[0040] In this embodiment, the distance between the outer rectangular groove 401 and the side surface of the foundation pit is 10 - 25 cm, and the circular inner groove 402 and the annular outer groove 403 are in a concentric relative position relationship.

[0041] There are 4 vertical grooves 404 provided on a single annular outer groove 403.

[0042] In this embodiment, the 4 vertical grooves 404 correspond to 2 plain concrete piles e on the left and right sides of the reinforced concrete pile d.

[0043] In S4, the structure of the arc plate unit 3 includes an arc-shaped vertical plate 301 with a fan-shaped ring cross-section, a lower fixing column 302 provided on the lower surface of the arc-shaped vertical plate 301 and used for plugging the vertical groove 404, and an upper reinforcing groove 303 provided on the upper surface of the arc-shaped vertical plate 301 and used for plugging the top combined frame unit 5.

[0044] In this embodiment, the outer diameter of the arc-shaped vertical plate 301 is equal to the outer diameter of the steel pipe 2, and their thicknesses are also equal. Therefore, the final reinforced concrete pile d and the plain concrete pile e can provide a parallel inner and outer side surface for the secant pile structure.

[0045] In addition, a total of two lower fixing columns 302 and two upper reinforcement grooves 303 are disposed on a single arc-shaped vertical plate 301 .

[0046] The two end surfaces 301a of the arc-shaped vertical plate 301 are also arc-shaped surfaces.

[0047] In this embodiment, the two narrower arc-shaped surfaces are set so as to allow the arc-shaped vertical plate 301 to fit the reinforced concrete pile d more closely and avoid a large amount of concrete leaking from the joint gap.

[0048] In S4, the structure of the top combined frame unit 5 includes a circular ring 501 arranged at a position above the steel pipe 2 and used to connect and reinforce the four arc-shaped vertical plates 301, a protruding column 502 arranged on the lower surface of the circular ring 501 and used to insert into the upper reinforcement groove 303, a radial rod 503 arranged on the circular ring 501, and a hook 504 arranged on the radial rod 503 and used to suspend and correct the position of the steel cage 1.

[0049] In this embodiment, the use position of the circular ring 501 is located directly above the original use position of the steel pipe 2, but the sizes of the two do not need to be consistent.

[0050] In addition, when the top assembly rack unit 5 is idle, the hook 504 can also serve as its hanging placement position.

[0051] The top assembly frame unit 5 further includes an annular groove 505 disposed on the inner surface of the circular ring 501 and used for inserting the radial rod 503 , and a sliding ring 506 disposed on the radial rod 503 and used for installing the hook 504 .

[0052] In this embodiment, the radial rod 503 can rotate circumferentially on the annular groove 505, and the sliding ring 506 can slide radially on the radial rod 503, ultimately ensuring that the hook 504 can provide a sufficient and comprehensive suspension positioning point for the steel cage 1.

[0053] In S5, the type of concrete poured into the arc-shaped plate unit 3 is super slow-setting concrete.

[0054] In this embodiment, the super slow-setting concrete has a more durable working performance compared to ordinary concrete, and thus can greatly extend the effective service life of the interlocking pile structure.

[0055] In S6, the width of the gap b between the reinforced concrete pile and the plain concrete pile in the interlocking pile structure is in the range of 0.5-1.2 cm.

[0056] In this embodiment, a gap b in the width range of 0.5 - 1.2 cm can ensure the docking stability of the "biting" action, that is, the reinforced concrete pile d and the plain concrete pile e fully support each other and integrate into a whole.

[0057] In S6, after the top combined frame unit 5 is removed, the upper end face of the reinforced concrete pile is leveled with concrete. After the upper end face leveling operation, the concrete base is poured inside the groove and outside the pile for the combined groove unit 4.

[0058] In this embodiment, the function of the leveling block f is to fully cover the steel reinforcement cage 1 so that it will not be exposed and is not easily corroded by water. The function of the concrete base g is to provide another concrete base for the entire biting pile structure, making the foundation pit support action more stable.

[0059] In addition, it should also be noted that: there is also a downward protruding steel-concrete section of the reinforced concrete pile d in the circular inner groove 402. Therefore, there is also an effect of strengthening the installation structure between the reinforced concrete pile d itself and the foundation pit, which can further enhance the foundation pit support strength of the biting pile structure.

[0060] The embodiments of the present invention have been described in detail above with reference to the drawings. However, the present invention is not limited to the above embodiments. Within the knowledge scope of those of ordinary skill in the art in the said technical field, various modifications can be made without departing from the gist of the present invention. These are all non-creative modifications and are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A construction method for foundation pit support based on the structure of secant piles, characterized in that The following steps are included in sequence: S1. Grooving the bottom surface of the foundation pit: a combined groove unit (4) for fixing and installing the steel cage (1), the steel pipe (2) and the arc plate unit (3) is opened on the bottom surface (a) of the foundation pit; S2, pouring reinforced concrete piles: inserting and installing the steel cage (1) and the steel pipe (2) on the combined slot unit (4), and then pouring concrete until the amount of concrete in the steel pipe (2) reaches a preset height; S3, initial solidification of the reinforced concrete pile: after all the concrete in the steel pipe (2) has been poured, the pile is left to stand for 2-5 hours to obtain a semi-solidified reinforced concrete pile, and then the steel pipe (2) is pulled up and removed; S4, positioning the plain concrete piles: inserting and installing the arc plate unit (3) on the combined slot unit (4) between two adjacent semi-solidified reinforced concrete piles, and installing the top combined frame unit (5) on the arc plate unit (3) and the semi-solidified reinforced concrete piles; S5, overall solidification of the interlocking pile: suspending and correcting the position of the steel cage (1) on the top assembly frame unit (5), pouring concrete into the paired arc plate units (3) until the amount of concrete in the arc plate units (3) reaches a preset height of the plain concrete pile; S6. Curing and forming of the interlocking piles: After all the concrete in the arc-shaped plate unit (3) has been poured, the concrete is allowed to stand for 10-12 hours, and then the arc-shaped plate unit (3) and the top assembly frame unit (5) are removed. The interlocking piles are then allowed to stand for 1-2 days to obtain the final interlocking pile structure for foundation pit support.

2. The construction method of foundation pit support based on the structure of secant piles according to claim 1, characterized in that: In S1, the structure of the combined groove unit (4) comprises an outer rectangular groove (401) arranged on the bottom surface (a) of the foundation pit, a circular inner groove (402) arranged in the outer rectangular groove (401) and used for inserting and installing the steel cage (1), an annular outer groove (403) arranged in the outer rectangular groove (401) and used for inserting and installing the steel pipe (2), and a vertical groove (404) arranged in the annular outer groove (403) and used for plugging and installing the arc plate unit (3).

3. A construction method for foundation pit support based on the structure of secant piles, as claimed in claim 2, wherein: Four vertical grooves (404) are provided on a single annular outer groove (403).

4. A construction method for foundation pit support based on the structure of secant piles, characterized in that: In S4, the structure of the arc-shaped plate unit (3) comprises an arc-shaped vertical plate (301) having a fan-shaped cross-section, a lower fixing column (302) arranged on the lower surface of the arc-shaped vertical plate (301) and used for plugging into the vertical groove (404), and an upper reinforcement groove (303) arranged on the upper surface of the arc-shaped vertical plate (301) and used for plugging into the top assembly rack unit (5).

5. A construction method for foundation pit support based on the structure of secant piles, characterized in that: The two end surfaces (301a) of the arc-shaped vertical plate (301) are also arc-shaped surfaces.

6. A construction method for foundation pit support based on the structure of secant piles, characterized in that: In S4, the structure of the top combined frame unit (5) includes a ring (501) arranged above the steel pipe (2) and used to connect and reinforce the four arc-shaped vertical plates (301), a protruding column (502) arranged on the lower surface of the ring (501) and used to insert into the upper reinforcement groove (303), a radial rod (503) arranged on the ring (501), and a hook (504) arranged on the radial rod (503) and used to suspend and correct the position of the steel reinforcement cage (1).

7. A construction method for foundation pit support based on a secant pile structure according to claim 6, characterized in that: The top combined frame unit (5) further includes an annular groove (505) arranged on the inner ring surface of the ring (501) and used to insert the radial rod (503), and a sliding ring (506) arranged on the radial rod (503) and used to install the hook (504).

8. A construction method for foundation pit support based on the structure of secant piles, characterized in that: In S5, the type of concrete poured into the arc-shaped plate unit (3) is super-retarding concrete.

9. A construction method for foundation pit support based on the structure of secant piles, characterized in that: In S6, the width range of the gap (b) between the reinforced concrete pile and the plain concrete pile in the secant pile structure is 0.5 - 1.2 cm.

10. A construction method for foundation pit support based on the structure of secant piles, characterized in that: In S6, after the top combined frame unit (5) is removed, the upper end surface of the reinforced concrete pile is leveled with concrete. After the upper end surface leveling operation, the concrete base is poured inside the groove and outside the pile of the combined groove unit (4).

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