A temporary boundary wall for protecting the safety of existing building structures and a method of using the same

Abstract

The present invention relates to the field of building construction, and is a temporary boundary wall and a method of using the same for protecting the safety of existing building structures. The boundary wall is arranged at the boundary between the undemolished area and the construction area, one side of the bottom of the boundary wall is connected to the structural foundation of the undemolished area, an outward expansion raft plate cast as one with the boundary wall is arranged on the other side of the bottom of the boundary wall, and an inner expansion raft plate cast as one with the boundary wall is arranged on the inner side of the top of the boundary wall near the undemolished area; a plurality of stub steel bars extend outward from the outward expansion raft plate, a brick membrane is abutted on the other end of the stub steel bars on the outward expansion raft plate, and sand and gravel aggregates and plain concrete cover plates are arranged from bottom to top between the outward expansion raft plate and the brick membrane, and the plain concrete cover plates are flush with the top surfaces of the outward expansion raft plate and the brick membrane. The safety of the existing building structures in the undemolished area of ​​the first phase is protected, the earthwork in the construction area of ​​the second phase is backfilled smoothly, the requirements for the later restoration and continuation of the underground part of the first phase are met, and the feasibility of the later restoration and continuation of the construction is provided.

Description

Technical Field

[0001] The invention relates to the field of building construction, in particular to a temporary boundary wall for protecting the safety of an existing building structure and a use method thereof. Background Art

[0002] With the sluggish situation of the real estate industry, urban renewal projects will become the dominant direction and idea of ​​the real estate industry in the future. Urban renewal projects are relatively complex and include many contents, mainly demolition, construction, and delivery. Each link is closely linked, which also makes the construction process more complicated. It is easy for some buildings to be unable to be demolished due to poor coordination of the owner unit, and then the continuous construction cannot be carried out. In this case, the construction unit should be flexible and adapt to local conditions to ensure that the construction progress can proceed normally and the construction project is delivered on schedule.

[0003] In a project undertaken by our company, there are two sections, Phase I and Phase II, where Phase I is the undemolished area and Phase II is the construction area. Due to the division between Phase I and Phase II, the underground structure of Phase I will be destroyed during the construction of Phase II, and the existing building structure in the undemolished area of ​​Phase I needs to be safely protected. At the same time, due to the division between Phase I and Phase II, the earthwork cannot be backfilled smoothly during the construction of Phase II, affecting the construction progress. Moreover, the underground part of Phase I needs to be restored after the construction of Phase II is completed.

[0004] Therefore, in response to the above problems, there is an urgent need for a temporary boundary wall to protect the safety of existing building structures, to protect the safety of existing building structures in the undemolished area of ​​the first phase, to ensure the smooth backfilling of earth in the second phase construction area, to meet the requirements for the later restoration and continued construction of the underground part of the first phase, to reduce construction costs, and to reduce construction difficulty. This is a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] The present invention aims to solve the above-mentioned problems, thereby providing a temporary boundary wall and a method of using the same for protecting the safety of existing building structures, which can protect the safety of existing building structures in the undemolished area of ​​the first phase, ensure the smooth backfilling of earthwork in the second phase construction area, meet the requirements for the later restoration and continued construction of the underground part of the first phase, reduce construction costs, reduce construction difficulty, and effectively reduce the additional costs incurred due to delays in the construction period due to the inability to backfill backfill soil; and provide feasibility for the later restoration and continued construction of the underground part of the undemolished area, saving the time cost and construction cost of the later restoration and continued construction of the underground part of the undemolished area.

[0006] The present invention solves the above-mentioned problem by adopting the following technical solution:

[0007] A temporary boundary wall for protecting the safety of existing building structures, wherein the boundary wall is arranged at the boundary between an undemolished area and a construction area, and the backfill soil of the construction area is blocked by the boundary wall, and the undemolished area is supported; one side of the bottom of the boundary wall is connected to the structural foundation of the undemolished area, and an outward expansion raft plate cast as one with the boundary wall is arranged on the other side of the bottom of the boundary wall, and the boundary wall is connected to the structural foundation as a whole to lift the bottom of the boundary wall to resist the lateral pressure of the backfill soil, and an inward expansion raft plate cast as one with the boundary wall is arranged on the inner side of the top of the boundary wall close to the undemolished area, and the boundary wall is connected to the building structure of the undemolished area as a whole through the inward expansion raft plate, so as to support the undemolished area, The top of the boundary wall is lifted to resist the lateral pressure of the backfill soil; a number of horizontally arranged steel bars are extended outward from the outward raft slab, and the said steel bars are reserved for the restoration and continued construction of the underground part of the non-demolished area; the other end of the steel bars on the outward raft slab abuts against a brick membrane arranged in the construction area; gravel aggregates and plain concrete cover plates are arranged in sequence from bottom to top between the outward raft slab and the brick membrane, and the plain concrete cover plates are flush with the top surfaces of the outward raft slab and the brick membrane; modified asphalt waterproof membrane is laid on the bottom of the outward raft slab, gravel aggregates and brick membrane, on the side of the brick membrane away from the outward raft slab, on the side of the boundary wall outside the basement, and on the top surfaces of the outward raft slab, the plain concrete cover plate and the brick membrane.

[0008] Preferably, a further technical solution of the present invention is:

[0009] Furthermore, a number of inner permanent steel bars are horizontally arranged and extend inwardly on the inner expanded raft slab. When the boundary wall is demolished, the number of inner permanent steel bars are conducive to connecting with the slab steel bars. The number of inner permanent steel bars are reserved for the restoration and continued construction of the underground part of the non-demolished area.

[0010] Furthermore, sleeves are sleeved on the stubble-reinforced steel bars and the inner permanent steel bars, and the inner diameter of the sleeves is 1mm-3mm larger than the diameters of the stubble-reinforced steel bars and the inner permanent steel bars.

[0011] Furthermore, the plurality of inner permanent steel bars are arranged at intervals and parallel to each other, and temporary additional steel bars are densely arranged between adjacent inner permanent steel bars.

[0012] Furthermore, a first steel plate waterstop is arranged between the outward-expanded raft slab and the sand and gravel aggregate, with the water-facing side of the first steel plate waterstop facing the bottom; a second steel plate waterstop is arranged on the inner side of the inward-expanded raft slab close to the undemolished area, with one side of the second steel plate waterstop extending inwardly out of the inward-expanded raft slab and with the water-facing side of the second steel plate waterstop facing the top; a third steel plate waterstop is arranged at the lower part of the boundary wall and above the outward-expanded raft slab, with the water-facing side of the third steel plate waterstop facing one side of the construction area.

[0013] Furthermore, the boundary wall, the outwardly expanded raft slab and the inwardly expanded raft slab are all integrally cast with structural steel bars and concrete.

[0014] Furthermore, the width of the inner-expanded raft slab is not less than 500 mm, the width of the outer-expanded raft slab is not less than 300 mm, and the length of the stubble steel bars is not less than 300 mm.

[0015] Furthermore, the lap length of the inner permanent steel bars and the temporary additional steel bars is not less than 2000 mm.

[0016] A method for using a temporary boundary wall for protecting the safety of an existing building structure comprises the following steps:

[0017] S1. First, the structural steel bars are chiseled out from the structural foundation of the undemolished area. Secondly, the structural steel bars of the overlapping boundary wall are tied to the structural steel bars on the structural foundation according to the design requirements, and the third water-stop steel strip is embedded. Finally, the formwork is set up and concrete is poured.

[0018] S2. When tying the structural reinforcement of the boundary wall, tie the structural reinforcement of the inner raft slab and the outer raft slab together, set up the formwork and pour the concrete of the inner raft slab and the outer raft slab;

[0019] S2-1. Pre-embed the second steel plate water stop in the inner expansion raft slab and the first steel plate water stop in the outer expansion raft slab to prepare for the demolition and connection work of the boundary wall;

[0020] S2-2. Reserve the inner permanent steel bars on the inner expansion raft for the future connection of the steel bars of the boundary wall after removal. At the same time, add more temporary additional steel bars on the inner expansion raft. The temporary additional steel bars are doubled to ensure that the main construction on both sides is the same as the design. The temporary additional steel bars should be bent downward for 15d.

[0021] S2-3, reserve stub steel bars on the outward expansion raft slab;

[0022] S2-4. PVC sleeves are installed on the stubble steel bars and the inner permanent steel bars, and the ends of the PVC sleeves are sealed by plugging. Mortar cannot enter the gap during concrete pouring;

[0023] S3. Building a brick membrane on the end of the stub steel bar away from the boundary wall on the outward-expanded raft slab, with the brick membrane abutting against the stub steel bar, thus reserving a foundation for subsequent pouring construction;

[0024] S4. Sand and gravel aggregates are filled between the expanded raft and the brick membrane to protect the stubble steel bars from corrosion;

[0025] S5. Add a plain concrete cover plate on top of the sand and gravel aggregate to separate the backfill soil above from the sand and gravel aggregate below, and at the same time strengthen the mechanical protection of the stubble steel bars;

[0026] S6. Expand the raft slab, sand and gravel aggregate, plain concrete cover slab, and brick membrane, lay the modified asphalt waterproofing membrane, and roll up the waterproofing membrane to facilitate the dismantling of the boundary wall and the continuation of the pouring in the future;

[0027] S7. When the construction of the construction area is completed, support measures are taken for the backfill soil in the construction area, and the boundary wall can be removed;

[0028] S8. When demolishing the boundary wall, demolish it step by step from top to bottom. When the boundary wall is demolished to the elevation of the modified asphalt waterproofing membrane, separate the modified asphalt waterproofing membrane from the boundary wall, retain the modified asphalt waterproofing membrane and demolish the wall of the remaining boundary wall as well as the plain concrete cover plate, sand and gravel aggregate, and the sleeves set on several stubble steel bars until the stubble steel bars are exposed;

[0029] S9. The permanent structural wall of the underground part of the undemolished area is constructed on the discarded steel bars, and connected with several inner permanent steel bars on the inner expanded raft as a whole to complete the construction of the permanent structural wall.

[0030] Compared with the prior art, the present invention adopting the above technical solution has the following outstanding features:

[0031] The present invention discloses a temporary boundary wall for protecting the safety of existing building structures, comprising a brick membrane, an outwardly expanded raft, an inwardly expanded raft, stubble steel bars, inner permanent steel bars, etc.; the wall has the advantages of strong practicability and convenient dismantling, and can protect the safety of existing building structures in the undemolished area of ​​the first phase, ensure smooth backfilling of earthwork in the second phase construction area, meet the requirements for the later restoration and continued construction of the underground part of the first phase, reduce construction costs, reduce construction difficulty, and can effectively reduce the additional costs incurred due to delays in the construction period due to the inability to backfill backfill soil; and provides feasibility for the later restoration and continued construction of the underground part of the undemolished area, saving the time cost and construction cost of the later restoration and continued construction of the underground part of the undemolished area. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of the side view structure of the present invention;

[0033] Figure 2 yes Figure 1 A schematic diagram of a local enlarged structure;

[0034] Figure 3 yes Figure 1 A schematic diagram of a local enlarged structure;

[0035] Figure 4 It is a schematic diagram of the top view structure of the present invention;

[0036] In the figure: 1. Brick membrane; 2. Outward-expanded raft; 3. Stubble steel bars; 4. Casing; 5. First steel plate waterstop; 6. Sand and gravel aggregate; 7. Plain concrete cover; 8. Modified asphalt waterproofing membrane; 9. Inner permanent steel bars; 10. Temporary additional steel bars; 11. Second steel plate waterstop; 12. Third steel plate waterstop; 13. Inward-expanded raft; 14. Boundary wall; 15. Structural foundation. DETAILED DESCRIPTION

[0037] The following description of the embodiments will help the public better understand the present invention, but the specific embodiments given by the applicant cannot and should not be regarded as limitations on the technical solutions of the present invention. Any changes to the definitions of components or technical features and / or formal but not substantial changes to the overall structure should be regarded as the scope of protection defined by the technical solutions of the present invention.

[0038] See also Figures 1 to 4 As shown, the technical solution of the present invention is as follows:

[0039] A temporary boundary wall for protecting the safety of an existing building structure. The boundary wall 14 is arranged at the boundary between an undemolished area and a construction area. The boundary wall 14 blocks the backfill soil of the construction area and supports the undemolished area. One side of the bottom of the boundary wall 14 is connected to a structural foundation 15 of the undemolished area, so that the boundary wall 14 and the structural foundation 15 of the undemolished area are connected as a whole to ensure the stability of the boundary wall 14 structure. An outward expansion raft 2 cast as a whole with the boundary wall 14 is arranged on the other side of the bottom of the boundary wall 14. The boundary wall 14 is connected to the structural foundation 15 as a whole by the outward expansion raft 2 to lift the bottom of the boundary wall 14 to resist the lateral pressure of the backfill soil. The inner side of the top of the boundary wall 14 near the undemolished area is provided with an inner expansion raft 13 cast as one with the boundary wall 14. The boundary wall 14 is connected to the building structure of the undemolished area as a whole through the inner expansion raft 13 to support the undemolished area and lift the top of the boundary wall 14 to resist the lateral pressure of the backfill soil. The arrangement of the outward expansion raft 2 and the inner expansion raft 13 is used to Continue the preparatory work for pouring; a number of horizontally arranged stub steel bars 3 are extended outward from the outward raft 2, and the several stub steel bars 3 are reserved for the restoration and continued construction of the underground part of the undemolished area. The other end of the stub steel bars 3 on the outward raft 2 is abutted against a brick membrane 1 set in the construction area. The brick membrane 1 can be laid in a traditional way for the foundation raft paper mold. Sand and gravel aggregate 6 and plain concrete cover slab 7 are arranged in sequence from bottom to top between the outward raft 2 and the brick membrane 1. The sand and gravel aggregate 6 is set for the later backfill soil. At the same time In order to protect the stubble steel bars 3 from corrosion, the plain concrete cover slab 7 is flush with the top surfaces of the outward-expanded raft slab 2 and the brick membrane 1; modified asphalt waterproofing membrane 8 is laid on the bottom of the outward-expanded raft slab 2, the sand and gravel aggregate 6, and the brick membrane 1, on the side of the brick membrane 1 away from the outward-expanded raft slab 2, the side of the boundary wall 14 outside the basement, and on the top surfaces of the outward-expanded raft slab 2, the plain concrete cover slab 7, and the brick membrane 1. The modified asphalt waterproofing membrane 8 can be laid conveniently when the outward-expanded raft slab 2 continues to be poured after the boundary wall 14 is removed.

[0040] Furthermore, a number of inner permanent steel bars 9 arranged horizontally extend inwardly on the inner expanded raft 13. When the boundary wall 14 is demolished, the number of inner permanent steel bars 9 can be connected to the slab steel bars. The number of inner permanent steel bars 9 are reserved for the restoration and continued construction of the underground part of the non-demolished area.

[0041] Furthermore, a sleeve 4 is provided on the stubble steel bars 3 and the inner permanent steel bars 9. The sleeve 4 is made of PVC material, and the inner diameter of the sleeve 4 is 1mm-3mm larger than the diameter of the stubble steel bars 3 and the inner permanent steel bars 9. The sleeve 4 is used to protect the stubble steel bars 3 and the inner permanent steel bars 9 to prevent the concrete from corroding the steel bars during pouring, and to facilitate disassembly when the boundary wall 14 is demolished. The gap between the sleeve 4 and the stubble steel bars 3 and the inner permanent steel bars 9 should not be too large to prevent cement slurry from entering the gap.

[0042] Furthermore, the plurality of inner permanent steel bars 9 are arranged at intervals and parallel to each other, and temporary additional steel bars 10 are densely distributed between adjacent inner permanent steel bars 9. The temporary additional steel bars 10 are doubled to ensure that the construction of the main bodies on both sides is the same as the design, so that the main bodies on both sides are connected as a whole according to the design requirements.

[0043] Furthermore, a first steel plate waterstop 5 is arranged between the outward-expanded raft 2 and the sand and gravel aggregate 6, and the water-facing side of the first steel plate waterstop 5 faces the bottom; a second steel plate waterstop 11 is arranged on the inner side of the inward-expanded raft 13 close to the undemolished area, one side of the second steel plate waterstop 11 extends inwardly from the inward-expanded raft 13, and the water-facing side of the second steel plate waterstop 11 faces the top; a third steel plate waterstop 12 is arranged at the lower part of the boundary wall 14 and above the outward-expanded raft 2, and the water-facing side of the third steel plate waterstop 12 faces one side of the construction area; the first steel plate waterstop 5, the second steel plate waterstop 11 and the third steel plate waterstop 12 provide waterproof protection for the continued pouring of the floor slab for the boundary between the undemolished area and the construction area after the boundary wall 14 is demolished, and provide reserve work for the later pouring after solidification.

[0044] Furthermore, the boundary wall 14, the outwardly expanded raft 2, and the inwardly expanded raft 13 are all integrally cast with structural steel bars and concrete; the structure of the boundary wall 14 can resist the lateral pressure of the backfill soil in the construction area.

[0045] Furthermore, the width of the inner expansion raft 13 is not less than 500 mm, the width of the outer expansion raft 2 is not less than 300 mm, and the length of the stubble steel bars 3 is not less than 300 mm.

[0046] Furthermore, the overlap length of the inner permanent steel bars 9 and the temporary additional steel bars 10 is not less than 2000 mm.

[0047] A method for using a temporary boundary wall for protecting the safety of an existing building structure comprises the following steps:

[0048] S1. First, the structural steel bars are chiseled out on the structural foundation 15 in the undemolished area. Secondly, the structural steel bars of the overlapping boundary wall 14 are tied to the structural steel bars on the structural foundation 15 according to the design requirements, and the third water-stop steel strip is embedded. Finally, the formwork is supported and concrete is poured;

[0049] S2, when tying the structural reinforcement of the boundary wall 14, tie the structural reinforcement of the inner expansion raft 13 and the outer expansion raft 2 together, set up the formwork and pour the concrete of the inner expansion raft 13 and the outer expansion raft 2;

[0050] S2-1, pre-embed the second steel plate water stop 11 in the inner expansion raft 13, and pre-embed the first steel plate water stop 5 in the outer expansion raft 2, in preparation for the removal of the boundary wall 14 and the continuation of the connection work;

[0051] S2-2, reserve the inner permanent steel bars 9 on the inner expansion raft 13 for the future connection of the steel bars after the boundary wall 14 is removed, and at the same time, densely arrange the temporary additional steel bars 10 on the inner expansion raft 13. The temporary additional steel bars 10 are doubled to ensure that the main body construction on both sides is the same as the design, and the temporary additional steel bars 10 should be bent downward by 15d;

[0052] S2-3, reserve stubble steel bars 3 on the outwardly expanded raft 2;

[0053] S2-4, a PVC sleeve 4 is set on the stubble steel bar 3 and the inner permanent steel bar 9, and the end of the PVC sleeve 4 is sealed by plugging, so that the mortar cannot enter the gap during the pouring of concrete;

[0054] S3, build a brick membrane 1 on the end of the stubble steel bar 3 on the outward-expanded raft 2 away from the boundary wall 14, and the brick membrane 1 and the stubble steel bar 3 are in contact, so as to reserve a foundation for subsequent pouring construction;

[0055] S4, filling sand and gravel aggregate 6 between the expanded raft 2 and the brick membrane 1, the purpose is to protect the stubble steel bars 3 from corrosion;

[0056] S5, adding a plain concrete cover 7 on the top of the gravel aggregate 6 to separate the upper backfill soil from the lower gravel aggregate 6, while strengthening the mechanical protection of the stubble steel bars 3;

[0057] S6, outward expansion raft 2, gravel aggregate 6, plain concrete cover 7, and brick membrane 1, laying modified asphalt waterproofing membrane 8, and rolling up the waterproofing membrane to facilitate the removal of the boundary wall 14 and the continuation of the pouring to make a preset;

[0058] S7. When the construction of the construction area is completed, support measures are taken for the backfill soil in the construction area, and the boundary wall 14 can be removed;

[0059] S8, when demolishing the boundary wall 14, gradually demolish it from top to bottom. When the boundary wall 14 is demolished to the elevation of the modified asphalt waterproofing membrane 8, separate the modified asphalt waterproofing membrane 8 from the boundary wall 14, retain the modified asphalt waterproofing membrane 8 and demolish the remaining wall of the boundary wall 14 as well as the plain concrete cover 7, sand and gravel aggregate 6, and the sleeves 4 set on the plurality of stubble steel bars 3 until the stubble steel bars 3 are exposed;

[0060] S9. The permanent structural wall of the underground part of the undemolished area is constructed on the discarded steel bars 3, and connected with several inner permanent steel bars 9 on the inner expanded raft 13 as a whole, and the subsequent waterproof backfill construction is completed to complete the permanent structural wall construction.

[0061] The present invention discloses a temporary boundary wall for protecting the safety of existing building structures, comprising a brick membrane 1, an outwardly expanded raft 2, an inwardly expanded raft 13, stubble steel bars 3, inner permanent steel bars 9, etc.; the wall has the advantages of strong practicability and convenient dismantling, and can protect the safety of existing building structures in the undemolished area of ​​the first phase, ensure smooth backfilling of earthwork in the second phase construction area, meet the requirements for the later restoration and continuation of the underground part of the first phase, reduce construction costs, reduce construction difficulty, and can effectively reduce the additional costs incurred due to delays in the construction period due to the inability to backfill backfill soil; and provides feasibility for the later restoration and continuation of the underground part of the undemolished area, saving the time cost and construction cost of the later restoration and continuation of the underground part of the undemolished area.

[0062] The above description is only a preferred feasible embodiment of the present invention, and does not limit the scope of rights of the present invention. All equivalent changes made using the contents of the present specification and its drawings are included in the scope of rights of the present invention.

Claims

1. A temporary boundary wall for protecting the safety of an existing building structure, characterized in that: The boundary wall is arranged at the boundary between the undemolished area and the construction area, and the backfill soil of the construction area is blocked by the boundary wall and the undemolished area is supported; one side of the bottom of the boundary wall is connected to the structural foundation of the undemolished area, and an outward expansion raft plate cast as one with the boundary wall is arranged on the other side of the bottom of the boundary wall. The boundary wall is connected to the structural foundation through the outward expansion raft plate to lift the bottom of the boundary wall as a whole to resist the lateral pressure of the backfill soil; an inward expansion raft plate cast as one with the boundary wall is arranged on the inner side of the top of the boundary wall close to the undemolished area, and the boundary wall is connected to the building structure of the undemolished area through the inward expansion raft plate. The structure is connected as a whole to support the undemolished area and lift the top of the boundary wall to resist the lateral pressure of the backfill soil; a number of horizontally arranged stub steel bars extend outward from the outward-expanded raft slab, and the said stub steel bars are reserved for the restoration and continued construction of the underground part of the undemolished area; the other end of the stub steel bars on the outward-expanded raft slab abuts against a brick membrane arranged in the construction area; sand and gravel aggregates and plain concrete cover plates are arranged from bottom to top between the outward-expanded raft slab and the brick membrane; at the bottom of the outward-expanded raft slab, sand and gravel aggregates and brick membrane, a plain concrete cover plate is flush with the top surface of the outward-expanded raft slab and the brick membrane; at the bottom of the outward-expanded raft slab, sand and gravel aggregates and the brick membrane, a brick membrane is arranged away from the brick membrane. Modified asphalt waterproofing membrane is laid on one side of the outward-expanded raft slab, the side of the boundary wall outside the basement, and the top surfaces of the outward-expanded raft slab, the plain concrete cover slab, and the brick membrane; a number of inner permanent steel bars are horizontally arranged extending inward from the inward-expanded raft slab. When the boundary wall is removed, the several inner permanent steel bars are convenient for connecting with the slab steel bars. The several inner permanent steel bars are reserved for the restoration and continued construction of the underground part of the non-demolished area; sleeves are sleeved on the stub steel bars and the inner permanent steel bars, and the inner diameter of the sleeves is 1mm-3mm larger than the diameter of the stub steel bars and the inner permanent steel bars; the several inner The permanent steel bars are arranged at intervals and parallel to each other, and temporary additional steel bars are densely arranged between adjacent inner permanent steel bars; a first steel plate waterstop is arranged between the outward-expanded raft slab and the sand and gravel aggregate, and the water-facing side of the first steel plate waterstop faces the bottom; a second steel plate waterstop is arranged on the inner side of the inward-expanded raft slab close to the undemolished area, and one side of the second steel plate waterstop extends inwardly from the inward-expanded raft slab, and the water-facing side of the second steel plate waterstop faces the top; a third steel plate waterstop is arranged at the lower part of the boundary wall and above the outward-expanded raft slab, and the water-facing side of the third steel plate waterstop faces one side of the construction area.

2. The temporary boundary wall for protecting the safety of existing building structures according to claim 1 is characterized by: The boundary wall, the outward expansion raft slab and the inward expansion raft slab are all integrally cast by structural steel bars and concrete.

3. The temporary boundary wall for protecting the safety of existing building structures according to claim 1 is characterized by: The width of the inner-expanded raft slab is not less than 500 mm, the width of the outer-expanded raft slab is not less than 300 mm, and the length of the stubble steel bars is not less than 300 mm.

4. The temporary boundary wall for protecting the safety of existing building structures according to claim 1 is characterized by: The lap length of the inner permanent steel bars and temporary additional steel bars shall not be less than 2000mm.

5. A method for using a temporary boundary wall for protecting the safety of an existing building structure according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. First, the structural steel bars are chiseled out from the structural foundation of the undemolished area. Secondly, the structural steel bars of the overlapping boundary wall are tied to the structural steel bars on the structural foundation according to the design requirements, and the third water-stop steel strip is embedded. Finally, the formwork is set up and concrete is poured. S2. When tying the structural reinforcement of the boundary wall, tie the structural reinforcement of the inner raft slab and the outer raft slab together, set up the formwork and pour the concrete of the inner raft slab and the outer raft slab; S2-1. Pre-embed the second steel plate water stop in the inner expansion raft slab and the first steel plate water stop in the outer expansion raft slab to prepare for the demolition and connection work of the boundary wall; S2-2. Reserve the inner permanent steel bars on the inner expansion raft for the future connection of the steel bars of the boundary wall after removal. At the same time, add more temporary additional steel bars on the inner expansion raft. The temporary additional steel bars are doubled to ensure that the main construction on both sides is the same as the design. The temporary additional steel bars should be bent downward for 15d. S2-3, reserve stub steel bars on the outward expansion raft slab; S2-4. PVC sleeves are installed on the stubble steel bars and the inner permanent steel bars, and the ends of the PVC sleeves are sealed by plugging. Mortar cannot enter the gap during concrete pouring; S3. Building a brick membrane on the end of the stub steel bar away from the boundary wall on the outward-expanded raft slab, with the brick membrane abutting against the stub steel bar, thus reserving a foundation for subsequent pouring construction; S4. Sand and gravel aggregates are filled between the expanded raft and the brick membrane to protect the stubble steel bars from corrosion; S5. Add a plain concrete cover plate on top of the sand and gravel aggregate to separate the backfill soil above from the sand and gravel aggregate below, and at the same time strengthen the mechanical protection of the stubble steel bars; S6. Expand the raft slab, sand and gravel aggregate, plain concrete cover slab, and brick membrane, lay the modified asphalt waterproofing membrane, and roll up the waterproofing membrane to facilitate the dismantling of the boundary wall and the continuation of the pouring in the future; S7. When the construction of the construction area is completed, support measures are taken for the backfill soil in the construction area, and the boundary wall can be removed; S8. When demolishing the boundary wall, demolish it step by step from top to bottom. When the boundary wall is demolished to the elevation of the modified asphalt waterproofing membrane, separate the modified asphalt waterproofing membrane from the boundary wall, retain the modified asphalt waterproofing membrane and demolish the wall of the remaining boundary wall as well as the plain concrete cover plate, sand and gravel aggregate, and the sleeves set on several stubble steel bars until the stubble steel bars are exposed; S9. The permanent structural wall of the underground part of the undemolished area is constructed on the discarded steel bars, and connected with several inner permanent steel bars on the inner expanded raft as a whole to complete the construction of the permanent structural wall.

Images