Method for removing underground air-raid shelters and simultaneously constructing a foundation pit

Abstract

The application discloses a method for removing underground air-raid shelters and simultaneously constructing foundation pits, which comprises the following construction steps: 1, construction of underground continuous walls and enclosure structures; 2, gap filling and simultaneous installation of air-raid shelter internal hoop type column formworks; 3, simultaneous construction of foam concrete filling of air-raid shelter interiors and soil body slope excavation; 4, first enclosure purlin setting and first horizontal support installation construction; 5, soil body excavation and second enclosure purlin and second horizontal support construction; 6, soil body excavation cushion layer and bottom plate construction; 7, air-raid shelter external hoop type column formwork support and overall pouring; 8, floor slab construction and reserved passage setting; 9, simultaneous removal of air-raid shelters and first horizontal supports; 10, simultaneous removal of second horizontal supports and air-raid shelters; and 11, foundation pit side wall construction. The technical scheme of the application realizes simultaneous construction of underground air-raid shelter removal and new foundation pit excavation, reduces construction cost, and has remarkable technical and economic benefits.

Description

Technical Field

[0001] This invention is applicable to foundation pit renovation projects, and is particularly applicable to projects where underground air-raid shelters are demolished and foundation pit construction is carried out simultaneously. Background Technology

[0002] With the development and continuous improvement of technology in the construction industry, corresponding construction techniques exist in their respective fields: foundation pit excavation and underground air-raid shelter demolition. Currently, in response to the green renovation concept in the construction industry, on the one hand, reasonable planning and renovation of air-raid shelters avoids unnecessary cost issues in terms of safety protection measures; on the other hand, the reinforcement of foundation pits during the demolition of related air-raid shelters allows for space expansion and reuse.

[0003] Air raid shelters are time-consuming and material-intensive to dismantle due to their robust structure, while foundation pit excavation requires support. However, in current social construction and renovation projects, the challenges of both dismantling air raid shelters and excavating foundation pits often arise from applying construction techniques in isolation, resulting in unsatisfactory construction processes, such as extended construction periods, increased costs, low material utilization, and increased construction waste.

[0004] In response to the above problems, it is of great importance to find a construction method that can simultaneously carry out the demolition of air-raid shelters and the construction of foundation pits, and can efficiently utilize structural characteristics, improve construction efficiency, and save costs. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the prior art by providing a method for clearing underground air-raid shelters and simultaneously constructing foundation pits. To achieve this objective, the invention employs the following technical solution:

[0006] The method for clearing underground air-raid shelters and simultaneously constructing foundation pits includes the following specific steps:

[0007] Step 1: Construction of diaphragm wall and retaining structure;

[0008] Construction was carried out on the underground continuous wall on the side closest to the air-raid shelter wall, and retaining structures were set up on the other three sides away from the air-raid shelter wall;

[0009] Step 2: Fill the gaps and simultaneously install the clamp-type column formwork inside the air-raid shelter. The specific method is as follows:

[0010] 2a. Clean up the soil between the diaphragm wall and the adjacent air-raid shelter sidewall, and form a gap between the diaphragm wall and the adjacent air-raid shelter sidewall after cleaning; fill the gap with cement mortar, and fill it to the same height as the ground.

[0011] 2b. Roughen the bottom slab of the air-raid shelter below the air-raid shelter passage, hoist the steel cage, and lower the steel cage into the bottom slab of the air-raid shelter through the air-raid shelter passage above the air-raid shelter. Insert the steel bars at the bottom of the steel cage into the bottom slab of the air-raid shelter. The steel cage is located directly below the air-raid shelter passage.

[0012] 2c. Install the internal clamp-type column formwork. The diameter of the internal clamp-type column formwork is smaller than the diameter of the air-raid shelter passage. The internal clamp-type column formwork is installed on the outside of the steel cage. The upper end of the internal clamp-type column formwork is flush with the upper surface of the top wall of the air-raid shelter.

[0013] Step 3: Simultaneous construction of filling the air-raid shelter with foamed concrete and excavating and sloping the soil:

[0014] The soil above the air-raid shelter near the underground continuous wall is preserved, and foamed concrete is poured into the air-raid shelter. The top surface of the foamed concrete is flush with the top of the internal clamp-type column formwork. The soil on the other three sides above the air-raid shelter is sloped from the ground to the top of the three side walls of the air-raid shelter. Then, the soil is horizontally excavated to the retaining structure, and the excavation depth is flush with the top of the three side walls of the air-raid shelter.

[0015] Step 4: Installation of the first waler and the first horizontal support:

[0016] The first waler is installed on the side of the enclosure structure closest to the air-raid shelter. The top of the first waler is lower than the top of the side wall of the air-raid shelter. A corbel is installed on the first waler. The first horizontal support is installed in the area between the first waler and the side wall of the air-raid shelter.

[0017] Step 5: Excavation of the soil and construction of the second waler and second horizontal support:

[0018] Excavate the soil below the first horizontal support to half the height of the side wall of the air-raid shelter, install a second waler on the retaining structure, install corbels on the second waler, and install the second horizontal support in the area between the second waler and the side wall of the air-raid shelter.

[0019] Step Six: Excavate the soil and construct the bottom sealing layer and reinforced concrete base slab. The specific methods are as follows:

[0020] 6a. Excavate the soil below the second horizontal support to the bottom of the air-raid shelter, and then pour the concrete for the bottom sealing layer. One side of the bottom sealing layer is poured to the retaining structure, and the other side is poured to the bottom of the air-raid shelter. The upper surface of the bottom sealing layer is flush with the lower surface of the air-raid shelter.

[0021] 6b. After the bottom sealing layer is completed, the reinforced concrete base slab is constructed on the bottom sealing layer. The height of the reinforced concrete base slab is the same as the height of the air-raid shelter base slab. During the construction process, the steel cage is hoisted and placed on the reinforced concrete base slab. The steel bars at the bottom of the steel cage are then inserted into the reinforced concrete base slab.

[0022] Step 7: External clamp-type column formwork support and complete pouring of the air-raid shelter:

[0023] Remove the soil from the air-raid shelter passage and the upper part of the air-raid shelter roof, and partially remove the cement mortar filling the gap between the air-raid shelter and the underground continuous wall, clearing the cement mortar until the upper end is flush with the upper end of the internal clamp-type column formwork; set external clamp-type column formwork on the outside of the steel cage on the reinforced concrete base slab, with the height of the external clamp-type column formwork being the same as the height of the internal clamp-type column formwork; then pour concrete into all the external clamp-type column formwork and the internal clamp-type column formwork, forming structural columns after pouring;

[0024] Step 8: Construction of Floor Slab 1 and Setting Up of Reserved Passageways:

[0025] A floor slab is erected above the structural column, and a reserved passage is set on the floor slab near the enclosure structure.

[0026] Step Nine: Simultaneous dismantling of the air-raid shelter and the first horizontal support:

[0027] Remove the first horizontal support and the first waler with corbels, and remove the air-raid shelter above the second horizontal support, the internal clamp-type column formwork and foam concrete. After partial removal, the upper end of the air-raid shelter is flush with the upper end of the foam concrete. Then, the second floor slab is erected above the air-raid shelter and the foam concrete, and a reserved passage is set on the second floor slab.

[0028] Step 10: Simultaneous dismantling of the second horizontal support and the air-raid shelter:

[0029] As shown in the figure, the second horizontal support and the second waler with corbels were removed, and the remaining air-raid shelter side walls, foamed concrete and internal clamp-type column formwork were cleared. The gap between the air-raid shelter floor slab and the underground continuous wall was filled with concrete.

[0030] Step 11: Construction of the foundation pit sidewalls:

[0031] Construction of the foundation pit sidewalls shall be carried out on the inner side of the enclosure near the diaphragm wall and the retaining structure, and the construction height of the foundation pit sidewalls shall be consistent with the height of the surrounding diaphragm wall and the retaining structure.

[0032] Preferably, in step two, the gap depth extends to the midpoint between the bottom slab of the air-raid shelter and the bottom of the diaphragm wall, and the gap length is greater than the length of the side wall of the air-raid shelter but less than the distance between the two sides of the retaining structure connected to the diaphragm wall.

[0033] As a preferred option, in step three, the slope angle is calculated based on the soil stability theory.

[0034] Preferably, in step four, the first horizontal support includes a first short-span horizontal support and a first long-span horizontal support. One end of the first short-span horizontal support is fixed to the corbel on the first waler, and the other end of the first short-span horizontal support is fixed to the side wall of the air-raid shelter. Both ends of the first long-span horizontal support are fixed to the corbel on the first waler, and the first long-span horizontal support is perpendicular to the first short-span horizontal support.

[0035] In step five, the second horizontal support includes a second short-span horizontal support and a second long-span horizontal support; the installation method of the second horizontal support is the same as that of the first horizontal support.

[0036] Preferably, in step four, the height difference between the top surface of the first waler and the top surface of the side wall of the air-raid shelter is 10cm.

[0037] Preferably, in step seven, the steel bars at the upper end of the steel cage extend out of the upper end of the structural column to form exposed rebars; in step eight, floor slab one is a precast floor slab, and the exposed rebars extending out of the upper end of the structural column are connected to floor slab one.

[0038] As a preferred embodiment, in step eleven, the sidewalls of the foundation pit are closely attached to the underground continuous wall and the retaining structure, and the reinforcing bars at the bottom of the sidewalls of the foundation pit are anchored to the bottom slab of the air-raid shelter and the reinforced concrete bottom slab.

[0039] The beneficial effects of this invention are:

[0040] (1) Compared with the process of excavating and demolishing simultaneously, the technical solution of the present invention realizes the simultaneous construction of underground air-raid shelter demolition and new foundation pit excavation, and also realizes the reverse construction method of foundation pit floor slab, which improves work efficiency, reduces construction costs, and has significant technical and economic benefits.

[0041] (2) In the construction process of this invention, foamed concrete is used to fill the air-raid shelter, which not only provides sufficient lateral force for the horizontal support and reduces the workload of the horizontal support, thus saving support costs, but also facilitates the removal of the top plate of the air-raid shelter and the construction of the floor slab, thereby improving work efficiency and showing significant technical and economic advantages.

[0042] (3) The present invention retains the original air-raid shelter floor during construction, reducing unnecessary building material waste, thereby reducing project cost and conforming to the concept of economic and environmental protection. Attached Figure Description

[0043] Figure 1 It is a three-dimensional diagram of the air-raid shelter and the surrounding soil.

[0044] Figure 2 This is a schematic diagram of the layout of the underground continuous wall and retaining structure in section AA.

[0045] Figure 3 It is a top view of the layout of the underground diaphragm wall and enclosure structure.

[0046] Figure 4 This is a schematic diagram showing the cement mortar filling of the gap between the underground continuous wall and the side wall near the air-raid shelter at section AA, as well as the simultaneous construction of the steel cage hoisting and the clamp-type column formwork inside the air-raid shelter.

[0047] Figure 5 This is a top view of the cement mortar filling of the gap between the underground continuous wall and the side wall near the air-raid shelter at section AA, as well as the simultaneous construction of the steel cage hoisting and the clamp-type column formwork inside the air-raid shelter.

[0048] Figure 6 This is a schematic diagram of the soil slope excavation and foam concrete filling during simultaneous construction.

[0049] Figure 7 It is a top view of the soil slope excavation and foam concrete filling during the simultaneous construction.

[0050] Figure 8 This is a schematic diagram of the first horizontal support structure.

[0051] Figure 9 This is a top view of the first horizontal support structure.

[0052] Figure 10 This is a schematic diagram of the soil excavation below the first horizontal support and the erection of the second horizontal support.

[0053] Figure 11 It is a cross-sectional view of the soil excavation below the second horizontal support, the pouring of the bottom sealing layer and reinforced concrete base slab, the hoisting of the steel cage, and the installation of the external clamp-type column formwork for the air-raid shelter.

[0054] Figure 12 It is a top view of the pouring of the bottom sealing layer and reinforced concrete base slab, as well as the hoisting of the steel cage and the installation of the external clamp-type column formwork for the air-raid shelter.

[0055] Figure 13 This is a schematic diagram of the casting of all clamp-type column formwork.

[0056] Figure 14 This is a top view of the casting of all clamp-type column formwork.

[0057] Figure 15It is a cross-sectional view of the removal of the external clamp-type column formwork of the air-raid shelter and the erection of the floor slab.

[0058] Figure 16 It is a top view of the removal of the external clamp-type column formwork of the air-raid shelter and the erection of the floor slab.

[0059] Figure 17 This is a schematic diagram of the structure of the air-raid shelter on the first floor, the removal of the formwork for the clamp-type columns inside the air-raid shelter, and the erection of the second floor slab.

[0060] Figure 18 This is a schematic diagram showing the demolition of the remaining structure below the second floor slab and above the bottom slab, as well as the concrete filling of the gap between the underground continuous wall and the bottom slab.

[0061] Figure 19 This is a schematic diagram of the construction of the foundation pit sidewall.

[0062] Figure 20 It is a construction process flow chart for clearing underground air-raid shelters and simultaneously constructing foundation pits.

[0063] In the diagram: 1-Diaphragm wall; 2-Retaining structure; 3-Air raid shelter passage; 4-Cement mortar; 5-Soil; 6-Foundation; 7-Foamed concrete; 8-Internal clamp-type column formwork; 9-External clamp-type column formwork; 10-Structural column; 11-First short-span horizontal support; 12-First long-span horizontal support; 13-Corner; 14-First waler; 15-Second short-span horizontal support; 16-Second long-span horizontal support; 17-Second waler; 18-Bottom sealing layer; 19-Reinforced concrete base slab; 20-Air raid shelter base slab; 21-Floor slab one; 22-Floor slab two; 23-Reserved passage; 24-Filling concrete; 25-Exposed rebar; 26-Exposed steel bars; 27-Rebar cage; 28-Air raid shelter roof slab. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0065] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0066] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0067] The method for clearing underground air-raid shelters and simultaneously constructing the foundation pit is illustrated in the overall flowchart below. Figure 20 As shown, the specific implementation steps include the following:

[0068] Step 1: Construction of diaphragm wall 1 and retaining structure 2:

[0069] according to Figure 1 and combined Figure 2 and Figure 3 As shown, a diaphragm wall 1 is constructed on the side closest to the air-raid shelter wall, and a retaining structure 2 is set on the other three sides away from the air-raid shelter wall. The retaining structure 2 and the diaphragm wall 1 enclose the outside of the air-raid shelter wall, providing the prerequisite for subsequent construction.

[0070] Step 2: Fill the gaps and simultaneously install the internal clamp-type column formwork 8 of the air-raid shelter. The specific method is as follows:

[0071] 2a. For example Figure 4 and Figure 5 As shown, the gap between the diaphragm wall 1 and the adjacent air-raid shelter sidewall is filled. The soil 5 between the diaphragm wall 1 and the adjacent air-raid shelter sidewall is cleaned. After cleaning, a gap is formed between the diaphragm wall 1 and the adjacent air-raid shelter sidewall. The depth of the gap reaches the middle position between the bottom plate 20 of the air-raid shelter and the bottom of the diaphragm wall 1. The length of the gap is greater than the length of the sidewall of the air-raid shelter and less than the distance between the two sides of the retaining structure 2 connected to the diaphragm wall 1. Then, cement mortar 4 is poured into the gap, and the pouring height is flush with the ground.

[0072] 2b. Roughen the bottom slab 20 of the air-raid shelter below the air-raid shelter passage 3, and hoist the steel cage 27. The steel cage 27 is hoisted into the bottom slab 20 of the air-raid shelter through the air-raid shelter passage above the air-raid shelter. The bottom of the steel cage 27 is attached to the bottom slab 20 of the air-raid shelter, and the steel cage 27 is perpendicular to the bottom slab 20 of the air-raid shelter. The steel cage 27 is located directly below the air-raid shelter passage 3.

[0073] 2c. Install the internal clamp-type column formwork 8. The diameter of the internal clamp-type column formwork 8 is smaller than the diameter of the air-raid shelter passage 3. The internal clamp-type column formwork 8 is installed on the outside of the reinforcing cage 27. After installation, an annular reserved gap is formed between the internal clamp-type column formwork 8 and the air-raid shelter passage 3. The reserved gap between the two can ensure the filling of foamed concrete 7 in the next step. Install the internal clamp-type column formwork 8 directly below the air-raid shelter passage 3. The internal clamp-type column formwork 8 is installed on the outside of the reinforcing cage 27. The inner side of the internal clamp-type column formwork 8 forms a pouring space for pouring concrete. The upper end of the internal clamp-type column formwork 8 is flush with the upper surface of the top wall of the air-raid shelter. The upper end of the internal clamp-type column formwork 8 is fixed inside the air-raid shelter passage 3, and the bottom end is fixed on the air-raid shelter bottom plate 20.

[0074] Step 3: Simultaneous construction of filling the air-raid shelter with foamed concrete 7 and slope excavation of soil 5:

[0075] like Figure 6 and Figure 7 As shown, the soil 5 on the side above the air-raid shelter closest to the underground continuous wall 1 is preserved. This serves as an operating platform during synchronous construction, where foamed concrete 7 is completely filled into the air-raid shelter interior using the gap reserved between the internal clamp-type column formwork 8 and the air-raid shelter passage 3. Foamed concrete 7 is poured into the air-raid shelter interior, with the top surface of the poured foamed concrete 7 flush with the top of the internal clamp-type column formwork 8. The soil 5 on the other three sides above the air-raid shelter is sloped from the ground to the top of the three side walls of the air-raid shelter, and then horizontally excavated to the retaining structure 2, with the excavation depth flush with the top of the three side walls of the air-raid shelter. The slope angle is calculated based on soil stability theory.

[0076] Step 4: Installation of the first waler 14 and the first horizontal support:

[0077] like Figure 8 and Figure 9As shown, a first waler 14 made of concrete is installed on the side of the enclosure structure 2 near the air-raid shelter. The top surface of the first waler 14 is lower than the top of the side wall of the air-raid shelter by 10cm. A corbel 13 is installed on the first waler 14. A first horizontal support is installed in the area between the first waler 14 and the side wall of the air-raid shelter. The height of the first horizontal support is not higher than the height of the first waler 14. The first horizontal support includes a first short-span horizontal support 11 and a first long-span horizontal support 12. One end of the first short-span horizontal support 11 is fixed to the corbel 13 on the first waler 14, and the other end of the first short-span horizontal support 11 is fixed to the side wall of the air-raid shelter. Both ends of the first long-span horizontal support 12 are fixed to the corbel 13 on the first waler 14, and the first long-span horizontal support 12 is perpendicular to the first short-span horizontal support 11.

[0078] Step 5: Excavation of soil 5 and construction of the second waler 17 and the second horizontal support:

[0079] like Figure 10 As shown, according to the construction method in step four, the soil 5 below the first horizontal support is excavated to half the height of the side wall of the air-raid shelter. A second waler 17 is installed on the retaining structure 2, and the height of the second waler 17 is flush with the height of the soil 5. A corbel 13 is installed on the second waler 17. A second horizontal support is installed in the area between the second waler 17 and the side wall of the air-raid shelter. The second horizontal support includes a second short-span horizontal support 15 and a second long-span horizontal support 16. The installation method of the second horizontal support is the same as that of the first horizontal support.

[0080] Step Six: Excavate soil 5 and construct the bottom sealing layer 18 and reinforced concrete base slab 19. The specific methods are as follows:

[0081] 6a. For example Figure 11 and Figure 12 As shown, the soil 5 below the second horizontal support is excavated to the bottom slab 20 of the air-raid shelter, and then the concrete of the bottom sealing layer 18 is poured. One side of the bottom sealing layer 18 is poured to the retaining structure 2, and the other side is poured to the bottom of the air-raid shelter bottom slab 20. The upper surface of the bottom sealing layer 18 is flush with the lower surface of the air-raid shelter bottom slab 20.

[0082] 6b. After the bottom sealing layer 18 is completed, the reinforced concrete base slab 19 is constructed on the bottom sealing layer 18. The height of the reinforced concrete base slab 19 is consistent with the height of the air-raid shelter base slab 20. The reinforcing bars in the reinforced concrete base slab 19 are inserted into the side of the air-raid shelter base slab 20 and fitted together. During the construction process, the reinforcing cage 27 is hoisted and placed on the reinforced concrete base slab 19. The reinforcing bars at the bottom of the reinforcing cage 27 are inserted into the reinforced concrete base slab 19 so that the bottom end of the reinforcing cage 27 fits into the reinforced concrete base slab 19 as one unit. The hoisting position of the reinforcing cage 27 on the reinforced concrete base slab 19 is determined according to the layout of the foundation pit.

[0083] Step 7: Supporting and pouring the external clamp-type column formwork of the air-raid shelter (9 sections).

[0084] like Figure 13 and Figure 14 As shown, the soil 5 above the air-raid shelter passage 3 and the top slab 28 of the air-raid shelter is removed, and the cement mortar 4 filling the gap between the air-raid shelter and the underground continuous wall 1 is partially removed, until the upper end of the cement mortar 4 is flush with the upper end of the internal clamp-type column formwork 8. According to the layout of the foundation pit, an external clamp-type column formwork 9 is set on the outside of the steel cage 27 on the reinforced concrete base slab 19, and the height of the external clamp-type column formwork 9 is the same as the height of the internal clamp-type column formwork 8; then concrete is poured into all the external clamp-type column formwork 9 and the internal clamp-type column formwork 8, and after the pouring is completed, a structural column is formed; the steel bars at the upper end of the steel cage 27 extend out of the upper end of the structural column and form exposed rebar 26.

[0085] In this embodiment, five external clamp-type column templates 9 are provided on the reinforced concrete base slab, and one internal clamp-type column template 8 is provided on the air-raid shelter base slab. The five external clamp-type column templates 9 and one internal clamp-type column template 8 are arranged in a rectangular array.

[0086] Step 8: Construction of floor slab 21 and setting up of reserved passageway 23:

[0087] like Figure 15 and Figure 16 As shown, a precast floor slab 21 is erected above the structural column. Exposed reinforcing bars 26 extending from the upper end of the structural column are connected to the floor slab 21. The floor slab 21 can perfectly fit the exposed reinforcing bars 26 at the upper end of the structural column. Two reserved passages 23 are set on the floor slab 21 near the enclosure structure 2 to facilitate subsequent construction.

[0088] Step Nine: Simultaneous dismantling of the air-raid shelter and the first horizontal support:

[0089] like Figure 17As shown, the first horizontal support and the first waler 14 with corbel 13 are removed, and the air-raid shelter part above the second horizontal support, the internal clamp-type column formwork 8 and foam concrete 7 are removed. After partial removal, the upper end of the air-raid shelter is flush with the upper end of the foam concrete 7. Then, the second floor slab 22 is erected. The second floor slab 22 is erected above the air-raid shelter and the foam concrete 7, and a reserved passage 23 is set on the second floor slab 22. The reserved passage 23 of the second floor slab 22 is located below the reserved passage 23 on the first floor slab 21.

[0090] Step 10: Simultaneous dismantling of the second horizontal support and the air-raid shelter:

[0091] like Figure 18 As shown, the second horizontal support and the second waler 17 with corbel 13 are removed, and the remaining air-raid shelter sidewalls, foam concrete 7 and internal clamp-type column formwork 8 are cleared. The gap between the air-raid shelter floor 20 and the underground continuous wall 1 is filled with concrete 24.

[0092] Step 11, Construction of the sidewalls of the foundation pit (25mm):

[0093] like Figure 19 As shown, the foundation pit sidewall 25 is constructed on the inner side of the enclosure near the underground continuous wall 1 and the enclosure structure 2. The foundation pit sidewall 25 is closely attached to the underground continuous wall 1 and the enclosure structure 2. The steel bars at the bottom of the foundation pit sidewall 25 are anchored to the air-raid shelter bottom slab 20 and the reinforced concrete bottom slab 19. The foundation pit sidewall 25 can overlap and fit with the first floor slab 21 and the second floor slab 22. The construction height of the foundation pit sidewall 25 is consistent with the height of the surrounding underground continuous wall 1 and enclosure structure 2.

[0094] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for clearing underground air-raid shelters and simultaneously constructing foundation pits, characterized in that, The specific steps include the following: Step 1: Construction of the diaphragm wall (1) and retaining structure (2); Construction was carried out on the underground continuous wall (1) on the side closest to the air-raid shelter wall, and the retaining structure (2) was set on the other three sides away from the air-raid shelter wall; Step 2: Fill the gaps and simultaneously install the clamp-type column formwork inside the air-raid shelter. The specific method is as follows: 2a. Clean up the soil (5) between the underground continuous wall (1) and the adjacent air-raid shelter side wall. After cleaning, a gap is formed between the underground continuous wall (1) and the adjacent air-raid shelter side wall. Cement mortar (4) is poured into the gap, and the pouring height is level with the ground. 2b. Roughen the bottom plate (20) of the air-raid shelter below the air-raid shelter passage (3), and hoist the steel cage (27). The steel cage (27) is hoisted into the bottom plate (20) of the air-raid shelter through the air-raid shelter passage (3) above the air-raid shelter. The bottom of the steel cage (27) is attached to the bottom plate (20) of the air-raid shelter. The steel cage (27) is located directly below the air-raid shelter passage (3). 2c. Install the internal clamp-type column formwork (8). The diameter of the internal clamp-type column formwork (8) is smaller than the diameter of the air-raid shelter passage (3). The internal clamp-type column formwork (8) is installed on the outside of the steel cage (27). The upper end of the internal clamp-type column formwork (8) is flush with the upper surface of the top wall of the air-raid shelter. Step 3: Fill the air-raid shelter with foamed concrete (7) and simultaneously excavate and slope the soil (5): The soil (5) on the side of the underground continuous wall (1) above the air-raid shelter is preserved, and foam concrete (7) is poured into the air-raid shelter. The top surface of the foam concrete (7) is flush with the top of the internal clamp-type column formwork (8). The soil (5) on the other three sides above the air-raid shelter is sloped from the ground to the top of the three side walls of the air-raid shelter. Then, the soil is horizontally excavated to the retaining structure (2). The excavation depth is flush with the top of the three side walls of the air-raid shelter. Step 4: Installation of the first waler (14) and the first horizontal support: A first waler (14) is installed on the side of the enclosure structure (2) close to the air-raid shelter. The top surface of the first waler (14) is lower than the top surface of the side wall of the air-raid shelter. A corbel (13) is installed on the first waler (14). A first horizontal support is installed in the area between the first waler (14) and the side wall of the air-raid shelter. Step 5: Excavation of soil (5) and construction of the second waler (17) and the second horizontal support: Excavate the soil (5) below the first horizontal support to half the height of the side wall of the air-raid shelter, set the second waler (17) on the retaining structure (2), set the corbel (13) on the second waler (17), and install the second horizontal support in the area between the second waler (17) and the side wall of the air-raid shelter. Step 6: Excavate the soil (5) and construct the bottom sealing layer (18) and reinforced concrete base slab (19). The specific methods are as follows: 6a. Excavate the soil (5) below the second horizontal support to the bottom plate (20) of the air-raid shelter, and then pour concrete for the bottom sealing layer (18). The bottom sealing layer (18) is poured to the retaining structure (2) on one side and extended to the bottom plate (20) of the air-raid shelter on the other side. The upper surface of the bottom sealing layer (18) is flush with the lower surface of the bottom plate (20) of the air-raid shelter. 6b. After the bottom sealing layer (18) is completed, the reinforced concrete base slab (19) is constructed on the bottom sealing layer (18). The height of the reinforced concrete base slab (19) is consistent with the height of the air-raid shelter base slab (20). During the construction process, the steel cage (27) is hoisted and placed on the reinforced concrete base slab (19). The steel bars at the bottom of the steel cage (27) are then inserted into the reinforced concrete base slab (19). Step 7: External clamp-type column formwork support (9) and complete pouring of the air-raid shelter: Remove the soil (5) above the air-raid shelter passage (3) and the top slab (28) of the air-raid shelter, and partially remove the cement mortar (4) filling the gap between the air-raid shelter and the underground continuous wall (1). Remove the cement mortar (4) until its upper end is flush with the upper end of the internal clamp-type column formwork (8). Set the external clamp-type column formwork (9) on the outside of the steel cage (27) on the reinforced concrete base slab (19). The height of the external clamp-type column formwork (9) is the same as the height of the internal clamp-type column formwork (8). Then pour concrete into all the external clamp-type column formwork (9) and the internal clamp-type column formwork (8). After the pouring is completed, a structural column is formed. Step 8, Construction of Floor Slab 1 (21) and Setting Up of Reserved Passageway (23): A floor slab (21) is erected above the structural column, and a reserved passage (23) is set on the floor slab (21) near the enclosure structure (2); Step Nine: Simultaneous dismantling of the air-raid shelter and the first horizontal support: Remove the first horizontal support and the first waler (14) with corbel (13), and remove the air-raid shelter part above the second horizontal support, the internal clamp-type column formwork (8) and foam concrete (7). After partial removal, the upper end of the air-raid shelter is flush with the upper end of the foam concrete (7). Then, the second floor slab (22) is erected. The second floor slab (22) is erected above the air-raid shelter and the foam concrete (7), and a reserved passage (23) is set on the second floor slab (22). Step 10: Simultaneous dismantling of the second horizontal support and the air-raid shelter: Remove the second horizontal support and the second waler (17) with corbel (13), and remove the remaining air-raid shelter sidewalls, foam concrete (7) and internal clamp-type column formwork (8), and fill the gap between the air-raid shelter floor slab (20) and the underground continuous wall (1) with concrete (24). Step 11, Construction of the pit sidewalls (25): Construction of the pit sidewall is carried out on the inner side of the enclosure near the diaphragm wall (1) and the enclosure structure (2). The construction height of the pit sidewall (25) is consistent with the height of the surrounding diaphragm wall (1) and enclosure structure (2).

2. The method for clearing underground air-raid shelters and simultaneously constructing foundation pits according to claim 1, characterized in that, In step two, the gap depth extends to the middle of the bottom of the air-raid shelter floor slab (20) and the bottom of the underground continuous wall (1), and the gap length is greater than the length of the side wall of the air-raid shelter and less than the distance between the two sides of the enclosure structure (2) connected to the underground continuous wall (1).

3. The method for clearing underground air-raid shelters and simultaneously constructing foundation pits according to claim 1, characterized in that, In step three, the slope angle is calculated based on the soil stability theory.

4. The method for clearing underground air-raid shelters and simultaneously constructing foundation pits according to claim 1, characterized in that, In step four, the first horizontal support includes a first short-span horizontal support (11) and a first long-span horizontal support (12). One end of the first short-span horizontal support (11) is fixed to the corbel (13) on the first waler (14), and the other end of the first short-span horizontal support (11) is fixed to the side wall of the air-raid shelter. The two ends of the first long-span horizontal support (12) are respectively fixed to the corbel (13) on the first waler (14), and the first long-span horizontal support (12) is perpendicular to the first short-span horizontal support (11). In step five, the second horizontal support includes a second short-span horizontal support (15) and a second long-span horizontal support (16); the installation method of the second horizontal support is the same as that of the first horizontal support.

5. The method for clearing underground air-raid shelters and simultaneously constructing foundation pits according to claim 1, characterized in that, In step four, the height difference between the top surface of the first waler (14) and the top surface of the side wall of the air-raid shelter is 10cm.

6. The method for clearing underground air-raid shelters and simultaneously constructing foundation pits according to claim 1, characterized in that, In step seven, the steel bars at the upper end of the steel cage (27) extend out of the upper end of the structural column and form exposed rebars (26); in step eight, floor slab one (21) is a precast floor slab, and the exposed rebars (26) extending out of the upper end of the structural column are connected to floor slab one (21).

7. The method for clearing underground air-raid shelters and simultaneously constructing foundation pits according to claim 1, characterized in that, In step eleven, the pit sidewall (25) is closely attached to the underground continuous wall (1) and the retaining structure (2), and the steel bars at the bottom of the pit sidewall (25) are installed into the air-raid shelter bottom slab (20) and the reinforced concrete bottom slab (19).

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