Construction method of layered and zoned pouring of large volume foundation

Abstract

The present invention relates to a layered and zoned casting construction method for a large-volume cap, comprising the following steps: driving steel sheet piles along the excavation edge of the cap foundation pit to cast bottom concrete; relying on the horizontal ring beam and longitudinal steel support of the lowest layer to erect a mobile work platform; performing cap casting construction layer by layer from bottom to top until the cap is fully constructed; after the tie beam steel mesh is tied, it is hoisted as a whole into the foundation pit and connected and fixed with the cap steel mesh using vertical locking steel bars; installing the tie beam side formwork to cast the tie beam concrete. The beneficial effects of the present invention are: the boundary between the cap and the tie beam adopts a non-disassembly formwork, which reduces the difficulty of template installation, and there is no need to perform formwork removal in the later stage, shortening the construction period; the tie beam steel mesh adopts the method of overall binding and on-site hoisting, which improves the on-site construction efficiency; in addition, the tie beam longitudinal reinforcement is connected with the cap longitudinal reinforcement by vertical locking steel bars, which ensures the integrity of the structure and improves the bearing capacity of the structure.

Description

Technical Field

[0001] The invention relates to cast-in-place construction of a bridge pile foundation cap, and in particular to a layered and zoned casting construction method for a large-volume cap. Background Art

[0002] When constructing bridge pile foundation caps, the on-site pouring construction method is usually adopted. However, due to the large amount of hydration heat generated during the solidification and hardening process of cement concrete, and due to the large volume of the cap, the heat accumulates inside the cap and cannot be discharged, which can easily cause concrete cracking, thus affecting the safety of the structure. In order to avoid the influence of hydration heat when pouring large-volume concrete, it is usually adopted to pass cooling water into the concrete and reduce the volume of concrete pouring. However, for large-volume cap structures, if cooling water pipes are laid over a large area, it will affect the overall strength of the cap; if the partitioned pouring method is adopted, due to the limited working space in the foundation pit, the steel bar binding and formwork support are difficult, which not only increases the on-site workload and reduces the construction efficiency, but also increases the construction cost. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for layered and zoned casting of a large-volume foundation.

[0004] This large-volume cap layered and zoned casting construction method includes the following construction steps:

[0005] Step 1: Drive steel sheet piles along the excavation edge of the foundation pit, then excavate the foundation pit layer by layer and set up horizontal ring beams, transverse steel supports and longitudinal steel supports; construct bored piles and pour bottom concrete;

[0006] Step 2: Erect a mobile working platform based on the lowest horizontal ring beam and longitudinal steel support;

[0007] Step 3: The cap is cast in layers and zones. First, tie the lowest layer of the cap steel mesh in the foundation pit, install the embedded brackets close to both sides of the horizontal steel support, and spot weld the embedded brackets to the cap steel mesh; install and fix the non-removal formwork along the dividing line between the cap and the tie beam; after pouring the lowest layer of the cap concrete, transfer the mobile work platform to the upper layer of horizontal ring beams and longitudinal steel supports, and cast the cap layer by layer from bottom to top according to the above method until the cap is fully constructed;

[0008] Step 4: After the tie beam reinforcement mesh is tied, it is hoisted as a whole into the foundation pit and fixed with the pedestal reinforcement mesh using vertical locking steel bars; install the tie beam side formwork and pour the tie beam concrete.

[0009] Preferably, in step one, the horizontal ring beam, transverse steel supports and longitudinal steel supports in each layer form a support system, and stiffening angle supports are also provided in the support system.

[0010] Preferably, a support pulley is provided under the mobile working platform in step 2, and the support pulley is installed under the mobile working platform through an adjustable support screw. The support pulley can be supported on a horizontal ring beam, a longitudinal steel support or a base surface; the mobile working platform can slide longitudinally along the foundation pit.

[0011] Preferably, the cap steel mesh in step three includes cap longitudinal reinforcement, cap transverse reinforcement and cap vertical reinforcement, and the cap longitudinal reinforcement passes through the non-disassembly formwork. In the step, the ends of the cap longitudinal reinforcement are bent into circular arc-shaped butt elbows, and the ends of the tie beam longitudinal reinforcement are bent into circular arc-shaped butt elbows, and the vertical locking steel bars are simultaneously inserted into the butt elbows of the ends of the cap longitudinal reinforcement and the tie beam longitudinal reinforcement.

[0012] Preferably, in the step three, embedded corbels are installed close to both sides of the transverse steel supports, and the embedded corbels are spot welded to the pedestal steel mesh; then the pedestal side formwork is installed and fixed along the outer edge of the pedestal, and after the pedestal concrete reaches the design strength, the pedestal side formwork is removed and the gap between the pedestal and the foundation pit is backfilled and compacted with backfill sand and gravel, and a plain concrete covering layer is laid on the surface.

[0013] Preferably, in step three, the disassembly-free formwork is fixed on the longitudinal reinforcement of the base by a limiting sleeve, the limiting sleeve is sleeved on the longitudinal reinforcement of the base, a sealing ring is provided inside the limiting sleeve, a locking bolt is provided on the limiting sleeve, limiting sleeves are provided on both sides of the disassembly-free formwork, and the disassembly-free formwork is clamped between the limiting sleeves on both sides.

[0014] Preferably, in step three, after the mobile working platform is transferred to the upper horizontal ring beam and longitudinal steel support, the bottom layer of embedded corbels are welded to the transverse steel supports, and the bottom layer of transverse steel supports are cut off and removed near the embedded corbels, and the bottom layer of longitudinal steel supports and stiffening angle braces are removed at the same time.

[0015] Preferably, in step 4, the tie beam reinforcement mesh is tied as a whole outside the foundation pit, and the tie beam reinforcement mesh includes tie beam longitudinal reinforcement, tie beam transverse reinforcement and tie beam vertical reinforcement; after the tie beam reinforcement mesh is tied, it is hoisted into the foundation pit as a whole, and then the tie beam reinforcement mesh is connected and fixed to the pedestal longitudinal reinforcement using vertical locking steel bars; after the tie beam reinforcement mesh is installed and fixed, the tie beam side formwork is installed, and the tie beam concrete is poured; after the tie beam concrete reaches the design strength, the tie beam side formwork is removed, the gap between the tie beam and the foundation pit is backfilled and compacted in layers with backfill sand and gravel, and a plain concrete covering layer is laid on the surface.

[0016] The beneficial effects of the present invention are:

[0017] 1) The cap concrete is poured in layers and zones, which effectively avoids the hydration heat problem during large-volume concrete construction and ensures the strength of the concrete.

[0018] 2) The boundary between the pedestal and the tie beam uses a non-removable formwork, which reduces the difficulty of formwork installation and eliminates the need for formwork removal in the later stage, shortening the construction period.

[0019] 3) The tie beam reinforcement mesh is tied as a whole and hoisted on site, which improves the on-site construction efficiency; in addition, the tie beam longitudinal reinforcement and the pedestal longitudinal reinforcement are connected by vertical locking steel bars, which ensures the integrity of the structure and improves the bearing capacity of the structure.

[0020] 4) The mobile working platform is erected based on the horizontal support structure, which can provide a stable and reliable working space for the operators and ensure their safety.

[0021] 5) After the cap is poured in layers, the gap between the cap and the foundation pit is backfilled in layers, and the longitudinal and transverse horizontal steel supports in the foundation pit are removed. The horizontal ring beam is temporarily supported by pre-embedded corbels to ensure the stability of the foundation pit support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a construction process flow chart of layered and zoned pouring of large-volume caps;

[0023] Figure 2 This is a schematic diagram of the layered and zoned pouring construction of a large-volume foundation;

[0024] Figure 3 It is a schematic diagram of the foundation pit support and working platform structure;

[0025] Figure 4 yes Figure 3 Plan view of the foundation pit support structure of the middle AA section;

[0026] Figure 5 It is the plan view of the reinforcement binding of the cap;

[0027] Figure 6 yes Figure 5 Schematic diagram of the fixed structure of the template without disassembly at the A node;

[0028] Figure 7 This is a schematic diagram of the cap layered pouring and support replacement structure;

[0029] Figure 8 yes Figure 7 Plan view of the layered pouring and replacement support structure of the cap in the middle BB section;

[0030] Fig. 9 It is a structural plan view of the tie beam reinforcement being placed in place;

[0031] Fig.10 yes Fig. 9 Schematic diagram of the connection between the tie beam reinforcement and the cap reinforcement at the B node.

[0032] Markings in the figure: 1-cap, 11-cap longitudinal reinforcement, 12-cap transverse reinforcement, 13-cap vertical reinforcement, 14-cap side form, 15-cap concrete, 16-bored piles, 17-bottom concrete, 18-steel sheet piles, 19-horizontal ring beam, 110-transverse steel support, 111-longitudinal steel support, 112-reinforced angle brace, 113-embedded corbel, 114-backfill sand and gravel, 115-plain concrete cover, 2-tie beam, 21-tie beam longitudinal reinforcement, 22-tie beam transverse reinforcement, 23-tie beam vertical reinforcement, 24-butt elbow, 25-vertical locking steel bar, 27-tie beam side form, 3-non-removable formwork, 31-limiting sleeve, 32-sealing ring, 33-locking bolt, 4-mobile working platform, 41-adjustable support screw, 42-support pulley. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0034] As an example, Figures 1 to 10 As shown, a construction method for layered and zoned casting of a large-volume foundation includes the following construction steps:

[0035] Step 1: Drive steel sheet piles 18 along the excavation edge of the foundation pit, then excavate the foundation pit soil. After excavating one layer of the foundation pit soil, set up a support system consisting of a horizontal ring beam 19, a transverse steel support 110, a longitudinal steel support 111 and a stiffening angle brace 112; after the excavation of the foundation pit soil is completed, construct bored cast-in-place piles 16. After the bored cast-in-place piles 16 concrete reaches the design strength, pour the bottom seal concrete 17;

[0036] Step 2: Set up the mobile working platform 4 based on the bottom horizontal ring beam 19 and the longitudinal steel support 111; a support pulley 42 is provided under the mobile working platform 4, and the support pulley 42 is installed under the mobile working platform 4 through an adjustable support screw 41. The support pulley 42 can be supported on the horizontal ring beam 19, the longitudinal steel support 111 or the surface of the base 2; the mobile working platform 4 can slide longitudinally along the foundation pit.

[0037] Step 3: The cap 1 is cast in layers and zones. First, the lowest layer of the cap steel mesh is tied in the foundation pit. The cap steel mesh consists of the cap longitudinal reinforcement 11, the cap transverse reinforcement 12 and the cap vertical reinforcement 13. Pre-embedded corbels 113 are installed close to both sides of the transverse steel support 110, and the pre-embedded corbels 113 are spot welded to the cap steel mesh; then, the cap side formwork 14 is fixed along the outer edge of the cap 1, and the non-removal formwork 3 is fixed along the boundary line between the cap 1 and the tie beam 2; then, the lowest layer of the cap concrete 15 is cast. After the cap concrete 15 reaches the design strength, the cap side formwork 14 is removed, and the gap between the cap 1 and the foundation pit is backfilled and compacted with backfill sand and gravel 114, and a plain concrete covering layer 115 is laid on the surface; the removed cap concrete 15 is cast. The mobile working platform 4 is transferred to the upper horizontal ring beam 19 and the longitudinal steel support 111, and then the embedded corbel 113 of the lowest layer is welded to the transverse steel support 110, and the transverse steel support 110 is cut off and removed near the embedded corbel 113, and the longitudinal steel support 111 and the stiffening angle brace 112 are removed at the same time; according to the above method, the upper layer of the pedestal 1 is cast until the pedestal 1 is fully constructed; the pedestal longitudinal reinforcement 11 passes through the non-disassembly formwork 3, and in the step 4, the end of the pedestal longitudinal reinforcement 11 is bent into a circular arc-shaped butt elbow 24, and the end of the tie beam longitudinal reinforcement 21 is bent into a circular arc-shaped butt elbow 24, and the vertical locking steel bar 25 is simultaneously inserted into the butt elbow 24 at the end of the pedestal longitudinal reinforcement 11 and the end of the tie beam longitudinal reinforcement 21. The non-disassembly formwork 3 is fixed on the pedestal longitudinal reinforcement 11 by a limiting sleeve 31. The limiting sleeve 31 is sleeved on the pedestal longitudinal reinforcement 11. A sealing ring 32 is provided inside the limiting sleeve 31. A locking bolt 33 is provided on the limiting sleeve 31. Limiting sleeves 31 are provided on both sides of the non-disassembly formwork 3. The non-disassembly formwork 31 is clamped between the limiting sleeves 31 on both sides.

[0038] Step 4: The tie beam reinforcement mesh is tied as a whole outside the foundation pit. The tie beam reinforcement mesh consists of tie beam longitudinal reinforcement 21, tie beam transverse reinforcement 22 and tie beam vertical reinforcement 23. After the tie beam reinforcement mesh is tied, it is hoisted into the foundation pit as a whole, and then the tie beam reinforcement mesh is connected and fixed to the pedestal longitudinal reinforcement 11 using vertical locking reinforcement 25. After the tie beam reinforcement mesh is installed and fixed, the tie beam side formwork 27 is installed, and the tie beam concrete is poured. After the tie beam concrete reaches the design strength, the tie beam side formwork 27 is removed, and the gap between the tie beam 2 and the foundation pit is backfilled and compacted in layers using backfill sand and gravel 114, and a plain concrete cover layer 115 is laid on the surface.

Claims

1. A method for layered and zoned pouring of a large-volume foundation, characterized in that: The construction steps include: Step 1: Drive steel sheet piles (18) along the excavation edge of the foundation pit, then excavate the foundation pit soil layer by layer and set up horizontal ring beams (19), transverse steel supports (110) and longitudinal steel supports (111); construct bored cast-in-place piles (16) and pour bottom seal concrete (17); Step 2: erecting a mobile working platform (4) based on the bottom horizontal ring beam (19) and the longitudinal steel support (111); Step 3: The cap (1) is cast in layers and zones. First, the lowest layer of the cap steel mesh is tied in the foundation pit, and the embedded brackets (113) are installed close to both sides of the transverse steel support (110), and the embedded brackets (113) are fixed to the cap steel mesh by spot welding; the non-removal formwork (3) is installed and fixed along the boundary line between the cap (1) and the tie beam (2); after casting the lowest layer of the cap concrete (15), the mobile working platform (4) is transferred to the upper layer of the horizontal ring beam (19) and the longitudinal steel support (111), and the cap (1) is cast layer by layer from bottom to top according to the above method until the cap (1) is fully constructed; Step 4: After the tie beam reinforcement mesh is tied, the entire structure is hoisted into the foundation pit and connected and fixed with the cap reinforcement mesh using vertical locking steel bars (25); the tie beam side formwork (27) is installed and the tie beam concrete is poured.

2. The method for layered and zoned pouring of a large-volume foundation according to claim 1 is characterized in that: In the step 1, the horizontal ring beam (19), the transverse steel support (110) and the longitudinal steel support (111) in each layer form a support system, and a stiffening angle support (112) is also provided in the support system.

3. The method for layered and zoned pouring of a large-volume foundation according to claim 1 is characterized in that: In the second step, a support pulley (42) is provided below the mobile working platform (4), and the support pulley (42) is installed below the mobile working platform (4) through an adjustable support screw (41). The support pulley (42) can be supported on the horizontal ring beam (19), the longitudinal steel support (111) or the surface of the foundation (1); the mobile working platform (4) can slide longitudinally along the foundation pit.

4. The method for layered and zoned pouring of a large-volume foundation according to claim 1 is characterized in that: In the step 3, the cap steel mesh comprises cap longitudinal reinforcement (11), cap transverse reinforcement (12) and cap vertical reinforcement (13), and the cap longitudinal reinforcement (11) passes through the non-disassembly formwork (3). In the step 4, the end of the cap longitudinal reinforcement (11) is bent into a circular arc-shaped butt elbow (24), and the end of the tie beam longitudinal reinforcement (21) is bent into a circular arc-shaped butt elbow (24), and the vertical locking reinforcement (25) is simultaneously inserted into the butt elbows (24) at the end of the cap longitudinal reinforcement (11) and the end of the tie beam longitudinal reinforcement (21).

5. The method for layered and zoned pouring of a large-volume foundation according to claim 1 is characterized in that: In the step 3, embedded brackets (113) are installed close to both sides of the transverse steel support (110), and the embedded brackets (113) are fixed to the cap steel mesh by spot welding; then, the cap side form (14) is installed and fixed along the outer edge of the cap (1); after the cap concrete (15) reaches the designed strength, the cap side form (14) is removed and the gap between the cap (1) and the foundation pit is backfilled and compacted using backfill sand and gravel (114), and a plain concrete cover layer (115) is laid on the surface.

6. The method for layered and zoned pouring of a large-volume foundation according to claim 1 is characterized in that: In the step 3, the non-disassembly template (3) is fixed on the cap longitudinal reinforcement (11) by means of a limiting sleeve (31), the limiting sleeve (31) is sleeved on the cap longitudinal reinforcement (11), a sealing ring (32) is arranged inside the limiting sleeve (31), a locking bolt (33) is arranged on the limiting sleeve (31), both sides of the non-disassembly template (3) are provided with limiting sleeves (31), and the non-disassembly template (3) is clamped between the limiting sleeves (31) on both sides.

7. The method for layered and zoned pouring of a large-volume foundation according to claim 1 is characterized in that: In the step 3, after the mobile working platform (4) is transferred to the upper horizontal ring beam (19) and the longitudinal steel support (111), the embedded bracket (113) of the lowest layer is welded to the transverse steel support (110), and the transverse steel support (110) of the lowest layer is cut off and removed near the embedded bracket (113), and the longitudinal steel support (111) and the stiffening angle brace (112) of the lowest layer are removed at the same time.

8. The method for layered and zoned pouring of a large-volume foundation according to claim 3 is characterized in that: In the fourth step, the tie beam steel mesh is tied as a whole outside the foundation pit, and the tie beam steel mesh includes tie beam longitudinal reinforcement (21), tie beam transverse reinforcement (22) and tie beam vertical reinforcement (23); after the tie beam steel mesh is tied, it is hoisted as a whole into the foundation pit, and then the tie beam steel mesh is connected and fixed to the pedestal longitudinal reinforcement (11) using vertical locking reinforcement (25); after the tie beam steel mesh is installed and fixed, the tie beam side form (27) is installed, and the tie beam concrete is poured; after the tie beam concrete reaches the design strength, the tie beam side form (27) is removed, and the gap between the tie beam (2) and the foundation pit is backfilled and compacted in layers using backfill sand and gravel (114), and a plain concrete cover layer (115) is laid on the surface.

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