A shallow excavation foundation reinforcement structure and reinforcement method

Abstract

The present invention discloses a shallow excavation foundation reinforcement structure, including an original foundation and a newly added raft foundation, wherein the original foundation is an independent foundation or a strip foundation, and the newly added raft foundation includes a pin key, a foundation support beam, and a foundation support raft, and the bottom of the foundation support raft is replaced with compacted backfill soil from the center of the house as a bearing layer. The function of the pin key is to connect the foundation into a whole, the function of the foundation support beam is to serve as a connecting piece between the pin key and the foundation support raft, and the function of the foundation support raft is to improve the bearing capacity of the foundation on the basis of the shallow excavation foundation. The present invention also discloses a shallow excavation foundation reinforcement method. The shallow excavation foundation reinforcement structure and reinforcement method solve the problem that the original independent foundation or strip foundation reinforcement must be excavated to the bottom of the foundation, greatly reduces the foundation excavation depth, saves manpower and construction period, greatly reduces the foundation reinforcement cost, and reduces safety risks.

Description

Technical Field

[0001] The invention relates to the field of building technology, and more particularly to a shallow excavation foundation reinforcement structure and a reinforcement method. Background Art

[0002] With the continuous development of society, the reinforcement and renovation of old buildings has become an important issue facing the construction industry, and foundation reinforcement is an important part of the construction content of building reinforcement. Conventional foundation reinforcement methods mainly include: changing independent foundations to strip foundations, changing strip foundations to cross-orthogonal strip foundations, and changing strip foundations to raft foundations. During the foundation reinforcement construction process, in order to ensure that the bottom surfaces of the new and old foundations are flush, it is necessary to excavate to the original foundation bottom elevation before strengthening the foundation. However, when the original building foundation is buried deep, not only is the construction period long, but large-scale excavation equipment cannot be used during construction, and the construction efficiency is very low. It takes a lot of manpower and time, which increases the cost of engineering construction. At the same time, there are certain safety hazards.

[0003] Therefore, providing a shallow excavation foundation reinforcement structure and reinforcement method that can reduce the excavation depth of the foundation pit, reduce safety risks, and shorten the foundation excavation period while ensuring the foundation reinforcement requirements is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] In view of this, the present invention proposes a shallow excavation foundation reinforcement structure and reinforcement method, and its specific technical scheme is as follows:

[0005] A shallow excavation foundation reinforcement structure comprises an original foundation and a newly added raft foundation, wherein the original foundation is an independent foundation or a strip foundation, and the newly added raft foundation comprises pin keys, a foundation underpinning beam and a foundation underpinning raft, wherein the pin keys, the foundation underpinning beam and the foundation underpinning raft are all concrete beams with steel bars reserved at both ends, a plurality of pin keys are arranged through the wall of the original foundation, and the pin keys are arranged on the original foundation at a distance of 2 / 5 to 3 / 5 from the top of the wall, and the plurality of pin keys are arranged in a row at intervals horizontally; the foundation underpinning beam is arranged on both sides of the original foundation, and the whole is bounded to the plurality of pin keys through steel bars; the foundation underpinning raft is arranged on both sides of the foundation underpinning beam, and is bounded to the foundation underpinning beam through steel bars; and the bottom of the foundation underpinning raft is replaced with compacted house core backfill soil as a bearing layer.

[0006] By adopting the above technical scheme, in order to make the shallow excavation foundation bearing layer meet the bearing capacity requirements and further reduce the excavation depth of the foundation, the present invention performs artificial replacement and compaction construction on the bearing layer soil of the newly added foundation, thereby meeting the performance requirements of the bearing layer; the present invention avoids excavating to the bottom elevation position of the original brick wall strip foundation for foundation reinforcement, and excavates to the minimum buried depth of the newly added raft foundation for foundation reinforcement, thereby reducing the foundation excavation depth for reinforcement construction in a small space, facilitating construction, and improving the efficiency of reinforcement and reconstruction construction; the newly added raft foundation of the present invention is connected to the original brick wall strip foundation by pins and keys, and they jointly bear the upper structure load. According to the in-depth design, the load bearing path is optimized, and according to the original foundation bearing capacity appraisal result, the optimal proportion of the load borne by the new and old foundations is determined to meet the bearing capacity, safety and quality requirements of the reinforced foundation.

[0007] Preferably, the pin key is a block concrete beam having a length the same as the thickness of the wall of the original foundation, and steel bars are reserved at both ends of the block concrete beam.

[0008] Preferably, the foundation underpinning beam is a strip-shaped concrete beam with steel bars reserved at both ends.

[0009] Preferably, the foundation underpinning raft is a plate-shaped concrete beam with steel bars reserved at both ends.

[0010] A shallow excavation foundation reinforcement method comprises the following steps:

[0011] (1) Excavation of the original foundation covering soil: According to the location of the newly added raft foundation, determine the minimum burial depth of the foundation and the thickness of the foundation bearing layer, and then determine the excavation depth of the original foundation covering soil; then remove the surface soil on the original foundation to expose the upper part of the original foundation wall;

[0012] (2) Artificial foundation bearing layer: artificially replace the soil in the center of the house and compact it according to the thickness of the foundation bearing layer;

[0013] (3) Opening holes and pin key construction in the original foundation: Drill several through holes arranged horizontally at intervals on the original foundation wall, make a pin key in each through hole with the same length as the thickness of the original foundation wall and the same cross-sectional size as the cross-sectional size of the through hole, and reserve steel bars at both ends of the pin key;

[0014] (4) Construction of foundation replacement beams: Add foundation replacement beams on both sides of the original foundation wall, and reserve steel bars at both ends of the foundation replacement beams. The foundation replacement beams and pins are tied together through the reserved steel bars to form a whole, so that the foundation replacement beams and the original foundation walls are combined together;

[0015] (5) Construction of foundation underpinning raft slab: foundation underpinning raft slabs are added on both sides of the foundation underpinning beam, and steel bars are reserved at both ends of the foundation underpinning raft slabs. The foundation underpinning raft slabs and the foundation underpinning beam are tied together into a whole through the reserved steel bars, so that the foundation underpinning raft slabs and the foundation underpinning beam are combined together.

[0016] Preferably, the construction process of the pin key includes: measuring and positioning, static cutting at four corners, static cutting along the edge line, transporting the remaining blocks, chiseling and trimming, laying reserved steel bars, fixing the quick-closing net, and pouring grouting material.

[0017] Preferably, the specific construction process of pouring grouting material in the pin-key construction process includes: construction preparation, interface treatment, formwork support, grouting, maintenance, and formwork removal.

[0018] Preferably, the construction of the foundation replacement beam in step (4) should be carried out only after the strength of the concrete beam constituting the pin key in step (3) reaches the design requirement.

[0019] Preferably, during the binding process of the foundation underpinning raft slab and the foundation underpinning beam, elevation control measures shall be adopted to ensure the accuracy of the height difference between the foundation underpinning raft slab and the foundation underpinning beam on both sides.

[0020] The present invention solves the problem that the original independent foundation or strip foundation reinforcement must be excavated to the bottom of the foundation, greatly reduces the foundation excavation depth, saves manpower and construction period, greatly reduces the foundation reinforcement cost, and reduces safety risks. It is suitable for almost all renovation projects of strip foundation reinforcement construction of old masonry structures and has a high value of promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 It is a side view of a shallow excavation foundation reinforcement structure of the present invention.

[0023] Figure 2 It is a front view of a shallow excavation foundation reinforcement structure of the present invention.

[0024] Figure 3 It is a schematic diagram of the pin key hole of the present invention.

[0025] Figure 4 This is a schematic diagram of the structure of the template support at the pin key position.

[0026] Figure 5Schematic diagram of the elevation control measures used in the connection process between the foundation underpinning raft slab and the foundation underpinning beam.

[0027] In the figure, 1-original foundation, 2-pin key, 3-foundation replacement beam, 4-foundation replacement raft, 5-rebar, 6-quick and easy closing net, 7-wooden beam, 8-wooden formwork, 9-side formwork diagonal brace. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example:

[0030] According to the following Figure 1-5 A shallow excavation foundation reinforcement structure and a reinforcement method according to an embodiment of the present invention are described in detail.

[0031] like Figure 1 , Figure 2 As shown, an embodiment of the present invention discloses a shallow excavation foundation reinforcement structure, including an original foundation 1 and a newly added raft foundation, wherein the original foundation 1 is an independent foundation or a strip foundation, and the newly added raft foundation includes a pin key 2, a foundation supporting beam 3 and a foundation supporting raft 4, wherein the pin key 2 serves to connect the foundation into a whole, the foundation supporting beam 3 serves as a connecting piece between the pin key 2 and the foundation supporting raft 4, and the foundation supporting raft 4 serves to improve the bearing capacity of the foundation on the basis of the shallow excavation foundation.

[0032] Specifically, the pin keys 2, foundation underpinning beams 3 and foundation underpinning raft slabs 4 are all concrete beams with steel bars reserved at both ends. A plurality of pin keys 2 are arranged through the wall of the original foundation 1, and the pin keys 2 are arranged on the original foundation 1 at a distance of 2 / 5-3 / 5 from the top of the wall, and a plurality of pin keys 2 are arranged in a row at horizontal intervals; the foundation underpinning beams 3 are arranged on both sides of the original foundation 1, and the whole is tied together with the plurality of pin keys 2 through steel bars; the foundation underpinning raft slabs 4 are arranged on both sides of the foundation underpinning beams 3, and are tied together with the foundation underpinning beams 3 through steel bars; the bottom of the foundation underpinning raft slabs 4 is replaced with compacted backfill soil from the center of the house as a bearing layer.

[0033] Furthermore, the pin key 2 is a block concrete beam with the same length as the wall thickness of the original foundation 1, and steel bars are reserved at both ends of the block concrete beam. The foundation underpinning beam 3 is a strip concrete beam with steel bars reserved at both ends. The foundation underpinning raft 4 is a plate concrete beam with steel bars reserved at both ends.

[0034] The present invention is a technology for reinforcing a strip foundation of a brick wall by shallow excavation in a narrow space of an artificial bearing layer. The technology refers to reinforcing a building foundation indoors with a narrow space (the minimum size reaches 3m wide by 5m long). In order to reduce the excavation depth and the construction difficulty, the excavation depth is reduced to the minimum burial depth of a newly added foundation (raft foundation). Then, the newly added raft foundation bearing layer is artificially transformed to ensure that the transformed bearing layer meets the bearing requirement of the newly added raft foundation. Then, the newly added foundation is constructed so that the new and old foundations are connected together. Specifically, a pin key 2 is set by passing reinforcement through the wall of an original foundation 1, and a foundation underpinning beam 3 and a foundation underpinning raft 4 are set at the pin key 2 to change the strip foundation into a raft foundation.

[0035] The technology of the present invention is different from the building displacement technology. It does not separate the building superstructure from the foundation, but adds a raft foundation and the original strip foundation to jointly bear the superstructure. This brick wall strip foundation reinforcement system is relatively novel and overcomes the disadvantage that the existing building foundation reinforcement construction is relatively difficult. On the basis of meeting the foundation bearing capacity, this technology reduces the excavation depth of the original foundation 1, provides a better method for the reinforcement construction of the brick wall strip foundation, and provides technical support and reference for similar engineering construction.

[0036] The embodiment of the present invention also discloses a shallow excavation foundation reinforcement method, comprising the following steps:

[0037] (1) Excavation of the original foundation covering soil: According to the position of the newly added raft foundation, determine the minimum burial depth of the foundation and the thickness of the foundation bearing layer, and then determine the excavation depth of the original foundation covering soil 1; then remove the surface soil on the original foundation 1 to expose the upper part of the wall of the original foundation 1.

[0038] (2) Artificial foundation bearing layer: artificially replace the soil in the center of the house and compact it according to the thickness of the foundation bearing layer.

[0039] In order to ensure that the backfill soil in the center of the house meets all performance indicators of the foundation bearing layer, the staff needs to determine the parameters such as the materials, material ratio, compaction coefficient, thickness of the backfill soil in the center of the house according to the actual situation on site, and then carry out construction work such as replacing and compacting the soil in the center of the house.

[0040] (3) Opening holes and pin key construction of the original foundation: Punch several through holes arranged horizontally at intervals on the wall of the original foundation 1, make a pin key 2 in each through hole with the same length as the thickness of the wall of the original foundation 1 and the same cross-sectional size as the cross-sectional size of the through hole, and reserve steel bars 5 at both ends of the pin key 2.

[0041] In view of the high risk of drilling holes for pin key 2, the concrete pin key 2 needs to be constructed separately first, and the foundation slab can be constructed after the concrete strength of pin key 2 reaches the design requirements. In addition, the size of pin key 2 is small, and the pouring of commercial concrete cannot be vibrated and the transportation of materials is difficult. At the same time, considering the construction progress requirements, the reinforcement construction of the foundation slab is a major node that affects the construction period of this project, so grouting materials are used.

[0042] The construction process of the pin key 2 includes: measuring and positioning, static cutting at four corners, static cutting along the edge (such as Figure 3 As shown), the remaining blocks are transported out, chiseled and trimmed, reserved steel bars are laid, the quick-closing net 6 is fixed (two layers to prevent leakage), and the grouting material is poured.

[0043] The specific construction process of pouring grouting material in the above-mentioned pin key 2 construction process includes: construction preparation, interface treatment, formwork support, grouting, maintenance, and formwork removal. Figure 4 That is the structural schematic diagram of the template support at the pin key 2 position. The steel bars 5 are reserved, and two layers of quick-closing nets 6 are hung on both sides of the pin key 2. The four sides of the quick-closing nets 6 are nailed to the brick wall. A groove is opened on one side above the pin key 2 to reserve a grouting channel.

[0044] (4) Construction of foundation replacement beam: add foundation replacement beams 3 on both sides of the original foundation 1 wall, and reserve steel bars at both ends of the foundation replacement beams 3. The foundation replacement beams 3 and the pin keys 2 are tied together to form a whole through the reserved steel bars, so that the foundation replacement beams 3 and the original foundation 1 wall are combined together.

[0045] (5) Construction of foundation underpinning raft slab: foundation underpinning raft slab 4 is added on both sides of foundation underpinning beam 3, and steel bars are reserved at both ends of the foundation underpinning raft slab 4. The foundation underpinning raft slab 4 and the foundation underpinning beam 3 are tied together to form a whole by the reserved steel bars, so that the foundation underpinning raft slab 4 and the foundation underpinning beam 3 are combined together.

[0046] During the binding process of the foundation underpinning raft 4 and the foundation underpinning beam 3, elevation control measures must be adopted to ensure the accuracy of the height difference between the foundation underpinning raft 4 and the foundation underpinning beam 3 on both sides. Figure 5 As described above, the elevation control is carried out with the help of wooden beams 7, wooden formworks 8 and side formwork diagonal braces 9, which is an existing elevation control measure.

[0047] The shallow excavation foundation reinforcement structure and reinforcement method of the present invention are suitable for foundation reinforcement projects, especially for independent foundation projects with a large foundation burial depth, and have better economic benefits. The foundation reinforcement structure can reduce the excavation depth of the foundation, reduce construction safety risks, reduce engineering workload, and has a high value for promotion and use.

[0048] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0049] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A shallow excavation foundation reinforcement method, characterized in that: The shallow excavation foundation reinforcement structure comprises an original foundation (1) and a newly added raft foundation, wherein the original foundation (1) is an independent foundation or a strip foundation, and the newly added raft foundation comprises a pin key (2), a foundation underpinning beam (3) and a foundation underpinning raft (4), wherein the pin key (2), the foundation underpinning beam (3) and the foundation underpinning raft (4) are all concrete beams with steel bars reserved at both ends, a plurality of pin keys (2) are arranged through the wall of the original foundation (1), and the pin keys (2) are arranged on the original foundation (1) at a distance of 2 / 5 to 3 / 5 from the top of the wall, and the plurality of pin keys (2) are arranged in a row at intervals horizontally; the foundation underpinning beam (3) is arranged on both sides of the original foundation (1), and the whole is tied to the plurality of pin keys (2) by steel bars to form a whole; the foundation underpinning raft (4) is arranged on both sides of the foundation underpinning beam (3), and is tied to the foundation underpinning beam (3) by steel bars to form a whole; the bottom of the foundation underpinning raft (4) is replaced with compacted house core backfill soil as a bearing layer; A shallow excavation foundation reinforcement method comprises the following steps: 1) Excavation of the original foundation covering soil: According to the position of the newly added raft foundation, determine the minimum burial depth of the foundation and the thickness of the foundation bearing layer, and then determine the excavation depth of the original foundation (1) covering soil; then, remove the surface soil on the original foundation (1) to expose the upper part of the wall of the original foundation (1); 2) Artificial foundation bearing layer: artificially replace the soil in the center of the house and compact it according to the thickness of the foundation bearing layer; 3) Opening holes and pin key construction of the original foundation: several horizontally spaced through holes are drilled on the wall of the original foundation (1), and a pin key (2) is made in each through hole, the length of which is the same as the thickness of the wall of the original foundation (1) and the cross-sectional size is consistent with the cross-sectional size of the through hole, and steel bars are reserved at both ends of the pin key (2); 4) Construction of foundation replacement beam: adding foundation replacement beams (3) on both sides of the original foundation (1) wall, and reserving steel bars at both ends of the foundation replacement beam (3). The foundation replacement beam (3) and the pin key (2) are tied together to form a whole through the reserved steel bars, so that the foundation replacement beam (3) and the original foundation (1) wall are combined together; 5) Construction of foundation underpinning raft slab: foundation underpinning raft slabs (4) are added on both sides of the foundation underpinning beam (3), and steel bars are reserved at both ends of the foundation underpinning raft slabs (4). The foundation underpinning raft slabs (4) and the foundation underpinning beam (3) are tied together to form a whole by means of the reserved steel bars, so that the foundation underpinning raft slabs (4) and the foundation underpinning beam (3) are combined together.

2. A shallow excavation foundation reinforcement method according to claim 1, characterized in that: The pin key (2) is a block concrete beam having a length equal to the thickness of the wall of the original foundation (1), and steel bars are reserved at both ends of the block concrete beam.

3. A shallow excavation foundation reinforcement method according to claim 2, characterized in that: The foundation underpinning beam (3) is a strip-shaped concrete beam with steel bars reserved at both ends.

4. A shallow excavation foundation reinforcement method according to claim 3, characterized in that: The foundation underpinning raft slab (4) is a plate-shaped concrete beam with steel bars reserved at both ends.

5. A shallow excavation foundation reinforcement method according to claim 1, characterized in that: In step 3), the construction process of the pin key (2) includes: measuring and positioning, static cutting at four corners, static cutting along the edge line, transporting the remaining blocks, chiseling and trimming, laying reserved steel bars, fixing the quick-closing mesh, and pouring grouting material.

6. A shallow excavation foundation reinforcement method according to claim 5, characterized in that: The specific construction process of pouring grouting materials in the pin key (2) construction process includes: construction preparation, interface treatment, formwork support, grouting, maintenance, and formwork removal.

7. A shallow excavation foundation reinforcement method according to claim 1, characterized in that: The construction of the foundation replacement beam (3) in step 4) must be carried out only after the strength of the concrete beam constituting the pin key (2) in step 3) reaches the design requirement.

8. A shallow excavation foundation reinforcement method according to claim 1, characterized in that: In step 5), during the binding process of the foundation underpinning raft plate (4) and the foundation underpinning beam (3), elevation control measures must be adopted to ensure the accuracy of the height difference between the foundation underpinning raft plate (4) and the foundation underpinning beam (3) on both sides.

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