Raft foundation side form structure and construction method thereof

Abstract

The present application provides a raft foundation side mold structure and its construction method, through improving the design of the raft foundation steel support and brick formwork, the crossbeam and the connecting beam of the support are supported on the ring beam of the brick formwork, which provides favorable lateral constraint for the retaining brick formwork, improves the cantilever force system of the brick formwork, and improves the bearing capacity of the brick formwork. Through the structure of the water outlet hole and the dewatering pipe, the water level height in the backfill soil is reduced, and the lateral pressure of the backfill soil on the brick formwork is reduced. The present application can effectively reduce the thickness of the brick formwork, thereby reducing the excavation amount and the backfill amount of the "pit in pit", and achieving the purpose of reducing cost and increasing benefit.

Description

Technical Field

[0001] This invention relates to a side formwork structure for a raft foundation and its construction method. Background Technology

[0002] In foundation pit engineering, to lay the raft foundation of the main building, a "pit within a pit" is usually excavated independently within a large foundation pit. Currently, the side formwork of the raft foundation in the "pit within a pit" widely adopts the following two forms: one is to directly use the support structure as the side formwork, such as piles, sloping rock walls, soil nailing walls, etc. However, the surface of such support structures is uneven, and the quality cannot be guaranteed when constructing external waterproofing on them, resulting in a high risk of system leakage; the other is to construct brick formwork in the pit as the base layer of external waterproofing and the side formwork of the raft foundation. However, conventional brick wall construction is difficult to meet the needs of increasingly deeper foundations, and the brick formwork often collapses due to the lateral pressure of the backfill soil. Summary of the Invention

[0003] The purpose of this invention is to provide a side formwork structure for raft foundations and its construction method.

[0004] To address the above problems, the present invention provides a raft foundation side formwork structure, comprising:

[0005] The dual-purpose support includes: spaced-apart columns 9, crossbeams 10, connecting beams 11, and scissor braces 12. The full-length crossbeams 10 are welded to the first side of the columns 9, the full-length connecting beams 11 are welded to the second side of the columns 9, and the top surface of the connecting beams 11 is close to the bottom of the crossbeams 10. The scissor braces 12 are welded to the third side of the columns 9, and the height of the scissor braces 12 is the same as the height of the crossbeams 10.

[0006] Brick mold 5;

[0007] The reinforced concrete ring beam 6 is set at the elevation of the crossbeam 10 and the connecting beam 11, and the reinforced concrete ring beam 6 is set on the upper part of the brick formwork 5.

[0008] The foundation beam 4 is set on the upper part of the brick formwork 5. The bottom of the foundation beam 4 is reinforced with steel bars 41 inserted at preset intervals into the bottom of the pit to resist the lateral force received by the upper brick formwork 5.

[0009] An embedded plate 31 with anchoring steel bars is embedded in the ring beam 6; the cross beam 10 and the connecting beam 11 arranged perpendicular to it extend to the side of the ring beam 6 and are welded to the embedded plate 31, providing strong lateral restraint for the brick formwork 5, changing the cantilever force system of the brick formwork 5, thereby reducing the design thickness of the brick formwork 5.

[0010] Furthermore, the aforementioned raft foundation side formwork structure also includes:

[0011] At the connection nodes of the crossbeam 10, the connecting beam 11 and the ring beam 6, a waterproof layer 71, a waterproof reinforcement layer 62, a water-swellable waterstop 81 and a waterstop ring 91 are sequentially provided.

[0012] Furthermore, in the aforementioned raft foundation side formwork structure, the waterproof reinforcing layer 62 is tightly attached to the brick formwork 5, and the waterproof layer 71 covers the waterproof reinforcing layer 62; the water-swellable waterstop 81 is tightly attached to the waterproof layer 71, and the water-swellable waterstop 81 surrounds the crossbeam 10 and the connecting beam 11 in a circle; the waterstop ring 91 is at a predetermined distance from the water-swellable waterstop 81, and the waterstop ring 91 surrounds the crossbeam 10 and the connecting beam 11 in a circle, and is fully welded together.

[0013] Furthermore, in the aforementioned raft foundation side formwork structure, the cross-connection points of the reinforcing bars of the ring beam 6, foundation beam 4, and structural column 61 connected to the brick formwork 5 are tied with steel wire.

[0014] Furthermore, in the aforementioned raft foundation side formwork structure, the columns 9, beams 10, connecting beams 11, and scissor braces 12 are all made of structural steel and are connected by welding.

[0015] Furthermore, in the aforementioned raft foundation side formwork structure, the crossbeam 10 of the dual-purpose bracket serves as a component supporting the horizontal reinforcing bars 8 of each raft foundation layer, and the top elevation of the crossbeam 10 is consistent with the bottom elevation of the horizontal reinforcing bar mesh 8 of each raft foundation layer.

[0016] Furthermore, in the aforementioned raft foundation side formwork structure, drainage pipes 7 are inserted at intervals in the brick formwork 5.

[0017] Furthermore, in the above-mentioned raft foundation side formwork structure, a trough is also provided between the pit wall 1 and the brick formwork 5, and backfill soil 14 is provided in the trough, the backfill soil 14 being level with the ground 2 outside the pit.

[0018] Furthermore, in the aforementioned raft foundation side formwork structure, a dewatering pipe 13 is installed in the trench outside the brick formwork 5.

[0019] According to another aspect of the present invention, a construction method for a raft foundation side formwork structure is provided, comprising:

[0020] Step S1: After the pit within the raft foundation is excavated to the designed bottom elevation, the site is leveled and a concrete cushion layer 3 is poured.

[0021] Step S2: Construct the foundation beam 4 on the pit bottom cushion layer 3;

[0022] Step S3: Build a brick formwork 5 on the foundation beam 4, and insert drainage pipes 7 into the brick formwork 5 at certain intervals.

[0023] Step S4: Construct a layer of brick formwork 5 to the elevation of the crossbeam 10 and connecting beam 11 of the double-purpose support. Tie the reinforcing bars of the ring beam 6 and structural column 61 on the brick formwork 5. Embed the pre-embedded plate 31 with anchoring reinforcing bars on the side of the ring beam 6.

[0024] Step S5: Pour concrete for the ring beam 6 and structural column 61 of this layer;

[0025] Repeat steps S3, S4, and S5 to complete the construction of the brick formwork 5 for each layer;

[0026] Step S6: Construct the waterproof layer 71 of the raft foundation on the side of the brick formwork 5, and make waterproofing at the connection position of the column 9 and beam 10 of the dual-purpose bracket and the ring beam 6.

[0027] Step S7: Weld and install the dual-purpose bracket column 9, crossbeam 10, connecting beam 11 and scissor brace 12 in the pit. The crossbeam 10, connecting beam 11 and scissor brace are connected by fillet weld 51 on one side of the column 9, and the connecting beam 11 is close to the bottom of the crossbeam 10. The crossbeam 10 and connecting beam 11 are extended to the side of the ring beam 6 and welded to the embedded plate 31 in the ring beam 6.

[0028] Step S8: Construct the waterproof reinforcement layer 62 at the connection node between the crossbeam 10, connecting beam 11 and ring beam 6 of the dual-purpose bracket, and cover the waterproof layer 71 tightly against the waterproof reinforcement layer; Construct the water-swellable waterstop 81 surrounding the crossbeam 10 and connecting beam 11 tightly against the waterproof layer 71; At a predetermined distance from the water-swellable waterstop 81, surround the crossbeam 10 and connecting beam 11 with a waterstop ring 91, and fully weld the connection.

[0029] Step S9: Install the dewatering pipe 13 on the outside of the brick formwork 5, and backfill soil 14 in layers in the trench between the pit wall 1 and the brick formwork 5 until it is level with the ground 2 outside the pit. Pump out the water accumulated in the backfill soil through the dewatering pipe 13.

[0030] Step S10: Tie the raft foundation reinforcement bars at the bottom of the pit and on the crossbeam 10;

[0031] Step S11: Pour the raft foundation concrete.

[0032] Compared with the prior art, the present invention improves the design of the raft foundation steel reinforcement support and brick formwork, so that the crossbeams and connecting beams of the support are supported on the ring beam of the brick formwork, which provides favorable lateral restraint for the retaining brick formwork, improves the cantilever force system of the brick formwork, and enhances the load-bearing capacity of the brick formwork.

[0033] This invention reduces the water level in the backfill soil by constructing drainage holes and dewatering pipes, thereby reducing the lateral pressure of the backfill soil on the brick formwork.

[0034] This invention can effectively reduce the thickness of the brick formwork, thereby reducing the amount of excavation and backfilling for "pit within a pit", achieving the goal of cost reduction and efficiency improvement. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the side formwork structure of a raft foundation according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of a dual-purpose support structure according to an embodiment of the present invention;

[0037] Figure 3 This is an elevation view of the side formwork structure of a raft foundation according to an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the connection nodes between the crossbeam, connecting beam and brick formwork of a dual-purpose support according to an embodiment of the present invention.

[0039] Figure 5 This is a cross-sectional view of the foundation beam according to an embodiment of the present invention. Detailed Implementation

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Figure 1 This is a cross-sectional view of the overall structure. Figure 2 This is a construction diagram of a dual-purpose bracket. Figure 3 Elevation view of the side formwork construction. Figure 4 This is a detailed drawing of the connection node between the crossbeam or connecting beam of the dual-purpose support and the brick formwork. Figure 5 This is a cross-sectional view of the foundation beam.

[0042] like Figures 1 to 5 As shown, the present invention provides a raft foundation side formwork structure, comprising:

[0043] The dual-purpose support includes: spaced-apart columns 9, crossbeams 10, connecting beams 11, and scissor braces 12. The full-length crossbeams 10 are welded to the first side of the columns 9, the full-length connecting beams 11 are welded to the second side of the columns 9, and the top surface of the connecting beams 11 is close to the bottom of the crossbeams 10. The scissor braces 12 are welded to the third side of the columns 9, and the height of the scissor braces 12 is the same as the height of the crossbeams 10.

[0044] Brick mold 5;

[0045] The reinforced concrete ring beam 6 is set at the elevation of the crossbeam 10 and the connecting beam 11, and the reinforced concrete ring beam 6 is set on the upper part of the brick formwork 5.

[0046] The foundation beam 4 is set on the upper part of the brick formwork 5. The bottom of the foundation beam 4 is reinforced with steel bars 41 inserted at preset intervals into the bottom of the pit to resist the lateral force received by the upper brick formwork 5.

[0047] An embedded plate 31 with anchoring steel bars is embedded in the ring beam 6; the cross beam 10 and the connecting beam 11 arranged perpendicular to it extend to the side of the ring beam 6 and are welded to the embedded plate 31, providing strong lateral restraint for the brick formwork 5, changing the cantilever force system of the brick formwork 5, thereby reducing the design thickness of the brick formwork 5.

[0048] The key point regarding dual-purpose supports is that when the raft foundation thickness exceeds 2000mm, a two-way steel mesh with a diameter of not less than 12mm and a spacing of not more than 300mm should be installed in the middle of the slab thickness. In actual project cases, the horizontal structural steel mesh in the raft foundation will have slightly larger steel bar specifications and a larger inter-layer spacing, but the spacing generally will not exceed 3000mm.

[0049] This invention improves the design of the raft foundation steel reinforcement support and brick formwork, so that the crossbeams and connecting beams of the support are supported on the ring beam of the brick formwork, providing favorable lateral constraints for the retaining brick formwork, improving the cantilever force system of the brick formwork, and increasing the load-bearing capacity of the brick formwork.

[0050] This invention reduces the water level in the backfill soil by constructing drainage holes and dewatering pipes, thereby reducing the lateral pressure of the backfill soil on the brick formwork.

[0051] This invention can effectively reduce the thickness of the brick formwork, thereby reducing the amount of excavation and backfilling for "pit-within-pit" foundations, achieving the goal of cost reduction and efficiency improvement. This invention can solve the problems of difficult side formwork erection, easy collapse, and poor waterproofing quality in ultra-deep raft foundations.

[0052] In one embodiment of the raft foundation side formwork structure of the present invention, it further includes:

[0053] At the connection nodes of the crossbeam 10, the connecting beam 11 and the ring beam 6, a waterproof layer 71, a waterproof reinforcement layer 62, a water-swellable waterstop 81 and a waterstop ring 91 are sequentially provided to effectively prevent leakage.

[0054] In one embodiment of the raft foundation side formwork structure of the present invention, the waterproof reinforcing layer 62 is closely attached to the brick formwork 5, and the waterproof layer 71 covers the waterproof reinforcing layer 62; the water-swellable waterstop 81 is closely attached to the waterproof layer 71, and the water-swellable waterstop 81 surrounds the crossbeam 10 and the connecting beam 11 in a circle; the waterstop ring 91 is at a predetermined distance from the water-swellable waterstop 81, and the waterstop ring 91 surrounds the crossbeam 10 and the connecting beam 11 in a circle, and is fully welded together.

[0055] In one embodiment of the raft foundation side formwork structure of the present invention, the cross-connection positions of the reinforcing bars of the ring beam 6, the foundation beam 4, and the structural column 61 connected to the brick formwork 5 are tied with steel wire.

[0056] In one embodiment of the raft foundation side formwork structure of the present invention, the column 9, the crossbeam 10, the connecting beam 11 and the scissor brace 12 are all steel sections and are connected by welding.

[0057] In one embodiment of the raft foundation side formwork structure of the present invention, the crossbeam 10 of the dual-purpose bracket serves as a component supporting the horizontal steel reinforcement 8 of each raft slab layer, and the top elevation of the crossbeam 10 is consistent with the bottom elevation of the horizontal steel reinforcement mesh 8 of each raft slab layer.

[0058] In one embodiment of the raft foundation side formwork structure of the present invention, drainage pipes 7 are inserted at intervals in the brick formwork 5.

[0059] In one embodiment of the raft foundation side formwork structure of the present invention, a trough is provided between the pit wall 1 and the brick formwork 5, and backfill soil 14 is provided in the trough, the backfill soil 14 being level with the ground 2 outside the pit.

[0060] In one embodiment of the raft foundation side formwork structure of the present invention, a dewatering pipe 13 is disposed in the trough outside the brick formwork 5.

[0061] This invention also provides a construction method for a raft foundation side formwork structure, comprising:

[0062] Step S1: After the pit within the raft foundation is excavated to the designed bottom elevation, the site is leveled and a concrete cushion layer 3 is poured.

[0063] Step S2: Construct the foundation beam 4 on the pit bottom cushion layer 3;

[0064] Step S3: Build a brick formwork 5 on the foundation beam 4, and insert drainage pipes 7 into the brick formwork 5 at certain intervals.

[0065] Step S4: Construct a layer of brick formwork 5 to the elevation of the crossbeam 10 and connecting beam 11 of the double-purpose support. Tie the reinforcing bars of the ring beam 6 and structural column 61 on the brick formwork 5. Embed the pre-embedded plate 31 with anchoring reinforcing bars on the side of the ring beam 6.

[0066] Step S5: Pour concrete for the ring beam 6 and structural column 61 of this layer;

[0067] Repeat steps S3, S4, and S5 to complete the construction of the brick formwork 5 for each layer;

[0068] Step S6: Construct the waterproof layer 71 of the raft foundation on the side of the brick formwork 5, and make waterproofing at the connection position of the column 9 and beam 10 of the dual-purpose bracket and the ring beam 6.

[0069] Step S7: Weld and install the dual-purpose bracket column 9, crossbeam 10, connecting beam 11 and scissor brace 12 in the pit. The crossbeam 10, connecting beam 11 and scissor brace are connected by fillet weld 51 on one side of the column 9, and the connecting beam 11 is close to the bottom of the crossbeam 10. The crossbeam 10 and connecting beam 11 are extended to the side of the ring beam 6 and welded to the embedded plate 31 in the ring beam 6.

[0070] Step S8: Construct the waterproof reinforcement layer 62 at the connection node between the crossbeam 10, connecting beam 11 and ring beam 6 of the dual-purpose bracket, and cover the waterproof layer 71 tightly against the waterproof reinforcement layer; Construct the water-swellable waterstop 81 surrounding the crossbeam 10 and connecting beam 11 tightly against the waterproof layer 71; At a predetermined distance from the water-swellable waterstop 81, surround the crossbeam 10 and connecting beam 11 with a waterstop ring 91, and fully weld the connection.

[0071] Step S9: Install the dewatering pipe 13 on the outside of the brick formwork 5, and backfill soil 14 in layers in the trench between the pit wall 1 and the brick formwork 5 until it is level with the ground 2 outside the pit. Pump out the water accumulated in the backfill soil through the dewatering pipe 13.

[0072] Step S10: Tie the raft foundation reinforcement bars at the bottom of the pit and on the crossbeam 10;

[0073] Step S11: Pour the raft foundation concrete.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0075] Obviously, those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A construction method for a side formwork structure of a raft foundation, characterized in that, A raft foundation side formwork structure is adopted, the raft foundation side formwork structure comprising: The dual-purpose support includes: spaced columns (9), crossbeams (10), connecting beams (11), and scissor braces (12), wherein the full-length crossbeams (10) are welded to the first side of the columns (9), the full-length connecting beams (11) are welded to the second side of the columns (9), and the top surface of the connecting beams (11) is close to the bottom of the crossbeams (10), and the scissor braces (12) are welded to the third side of the columns (9), and the height of the scissor braces (12) is the same as the height of the crossbeams (10); Brick mold (5); A reinforced concrete ring beam (6) is set at the elevation of the crossbeam (10) and the connecting beam (11), and the reinforced concrete ring beam (6) is set on the upper part of the brick formwork (5); The foundation beam (4) is set on the upper part of the brick formwork (5). The bottom of the foundation beam (4) is reinforced with steel bars (41) inserted at a predetermined interval to resist the lateral force received by the upper brick formwork (5). An embedded plate (31) with anchoring steel bars is embedded in the ring beam (6); the cross beam (10) and the connecting beam (11) arranged perpendicular to it extend to the side of the ring beam (6) and are welded to the embedded plate (31) to provide strong lateral restraint for the brick formwork (5). At the connection nodes of the crossbeam (10), the connecting beam (11) and the ring beam (6), a waterproof layer (71), a waterproof reinforcement layer (62), a water-swellable waterstop (81) and a waterstop ring (91) are provided in sequence. The waterproof reinforcement layer (62) is closely attached to the brick formwork (5), and the waterproof layer (71) covers the waterproof reinforcement layer (62); the water-swellable waterstop (81) is closely attached to the waterproof layer (71), and the water-swellable waterstop (81) surrounds the crossbeam (10) and the connecting beam (11) in a circle; the waterstop ring (91) is at a preset distance from the water-swellable waterstop (81), and the waterstop ring (91) surrounds the crossbeam (10) and the connecting beam (11) in a circle, and is fully welded together; The cross-connection points of the reinforcing bars of the ring beam (6), the foundation beam (4), and the structural column (61) connected to the brick formwork (5) are tied with steel wire; The columns (9), beams (10), connecting beams (11) and scissor braces (12) are all made of structural steel and are connected by welding. The crossbeam (10) of the dual-purpose bracket serves as a component supporting the horizontal steel mesh (8) of each raft slab. The top elevation of the crossbeam (10) is consistent with the bottom elevation of the horizontal steel mesh (8) of each raft slab. A drain pipe (7) is inserted in the middle of the brick mold (5); A fertilizer trough is also provided between the pit wall (1) and the brick formwork (5), and backfill soil (14) is provided in the fertilizer trough. The backfill soil (14) is level with the ground (2) outside the pit. The drainage pipe (13) is installed in the trough outside the brick formwork (5). The construction method includes: Step S1: After the pit within the raft foundation is excavated to the designed bottom elevation, the site is leveled and a concrete cushion layer is poured (3). Step S2, construct the foundation beam (4) on the pit bottom cushion layer (3); Step S3: Build a brick formwork (5) on the foundation beam (4) and insert drainage pipes (7) into the brick formwork (5) at certain intervals. Step S4: Construct a layer of brick formwork (5) to the elevation of the crossbeam (10) and connecting beam (11) of the double-purpose support. Tie the reinforcing bars of the ring beam (6) and structural column (61) on the layer of brick formwork (5). Embed a pre-embedded plate (31) with anchoring reinforcing bars on the side of the ring beam (6). Step S5: Pour concrete for the ring beam (6) and structural column (61) of this layer; Repeat steps S3, S4, and S5 to complete the construction of the brick formwork (5) for each layer; Step S6: Construct the waterproof layer (71) of the raft foundation on the side of the brick formwork (5), and make waterproofing at the connection position of the column (9), beam (10) and ring beam (6) of the dual-purpose bracket. Step S7: Weld and install the column (9), crossbeam (10), connecting beam (11) and scissor brace (12) of the dual-purpose bracket in the pit. The crossbeam (10), connecting beam (11) and scissor brace (12) are connected by fillet weld (51) on one side of the column (9), and the connecting beam (11) is close to the bottom of the crossbeam (10). The crossbeam (10) and the connecting beam (11) are extended to the side of the ring beam (6) and welded to the embedded plate (31) in the ring beam (6). Step S8: Construct a waterproof reinforcement layer (62) for the connection nodes of the crossbeam (10), connecting beam (11) and ring beam (6) of the dual-purpose bracket, and cover the waterproof layer (71) tightly against the waterproof reinforcement layer; Construct a water-swellable waterstop (81) that surrounds the crossbeam (10) and connecting beam (11) tightly against the waterproof layer (71); At a preset distance from the water-swellable waterstop (81), surround the crossbeam (10) and connecting beam (11) with a waterstop ring (91) and fully weld them together; Step S9: Install a dewatering pipe (13) on the outside of the brick formwork (5), and construct backfill soil (14) in layers in the trench between the pit wall (1) and the brick formwork (5) until it is level with the ground (2) outside the pit. Use the dewatering pipe (13) to pump out the water accumulated in the backfill soil. Step S10: Tie the raft foundation reinforcement bars at the bottom of the pit and on the crossbeam (10); Step S11: Pour the raft foundation concrete.

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