Method for constructing underground space in peripheral area of existing building through open caisson

Abstract

A method for constructing an underground space in a peripheral area of an existing building by using an open caisson belongs to the technical field of open caisson construction, and comprises the following steps: arranging an open caisson construction area in an area between the existing buildings, and constructing an uplift pile in an internal area of the open caisson to be constructed; the counter-force beam is constructed, so that the counter-force beam is fixedly connected with the uplift pile, the two ends of the counter-force beam are fixedly connected with the existing building, and the weight of the existing building is used as counter-force to play a role in assisting sinking of the open caisson; after the counter-force beam is constructed, the open caisson is constructed, the uplift piles are arranged in the open caisson, the stress state of the counter-force beam can be improved, the cross section of the counter-force beam can be reduced, in the area with the high underground water level, the uplift piles on the lower portion of the open caisson can serve as anti-floating components of the open caisson, the uplift piles in the open caisson can serve as partial columns of a basement, cost is effectively reduced, and the construction period is shortened. The uplift pile is arranged in the open caisson, and compared with the uplift pile arranged near the outer wall of the open caisson, the uplift pile has higher bearing capacity and can better play a role.

Description

Technical Field

[0001] The invention relates to the technical field of caisson construction, and in particular to a method for constructing an underground space in a surrounding area of ​​an existing building by utilizing a caisson. Background Art

[0002] A large number of existing buildings are not designed with underground parking lots. As the number of cars increases, parking becomes difficult. For existing buildings that are not designed with underground parking lots, caisson technology is often used to add three-dimensional mechanical garages. Traditional caisson technology excavates the earth in the well to sink the well shaft, and the ground is continuously extended to the well shaft until the designed elevation.

[0003] However, when the cross-section of the caisson is large and the soil is hard, it is difficult to sink the caisson only by relying on its own weight to overcome the lateral resistance between the outer wall of the caisson and the soil. At present, a reaction-force static pressure caisson sinking construction method has emerged (such as publication number CN108487280B), in which anchor piles / anti-pullout piles are set around the periphery of the caisson to be constructed, and a number of beams located above the caisson are provided on the top of the piles. Reserved holes are provided on the beams, and pull-up jacks are correspondingly provided on each of the reserved holes. The anchor pile beam reaction frame is used in conjunction with the jack to provide sinking force and pulling force for the caisson.

[0004] In the existing reaction-force static pressure caisson sinking construction method, the pull-out piles are arranged close to the outer peripheral side of the caisson (in order to avoid too much eccentricity when the jack loads the caisson). The sinking of the caisson will weaken the bearing capacity of the pull-out piles, and the reaction force of the caisson sinking is completely dependent on the pull-out piles and the crossbeams on their tops, which can easily lead to difficulty in sinking the caisson. After the bearing capacity of the pull-out piles is weakened, when the pile body is subjected to the reaction force of the caisson sinking, it may produce excessive deformation, cracks or even fractures. In addition, in areas with high groundwater levels, the anti-buoyancy bearing capacity of the caisson usually cannot meet the requirements. Summary of the invention

[0005] In order to solve the technical problem that the existing reaction-force static pressure caisson sinking construction method in the above-mentioned background technology, the pull-out piles are arranged close to the outer peripheral side of the caisson, and the sinking of the caisson will weaken the bearing capacity of the pull-out piles, which can easily lead to difficulty in sinking the caisson and damage to the pile body, the present invention provides a method for constructing an underground space in the surrounding area of ​​an existing building using a caisson.

[0006] The technical solution of the present invention is as follows: The present invention provides a method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson, which is specifically as follows: A caisson construction area is set up between existing buildings, and anti-pullout piles are constructed in the inner area of ​​the caisson to be constructed to serve as the mid-span support of the reaction beam, which can effectively share the load borne by the reaction beam, enhance the bearing capacity and stability of the reaction beam, reduce its cross-sectional size, and provide a reliable support structure for subsequent construction. In addition, the anti-pullout piles can also serve as anti-floating components during the use of the caisson and as vertical support components in the caisson; Construct reaction beams so that the reaction beams are fixedly connected to the pull-out piles, and both ends of the reaction beams are fixedly connected to the existing buildings, using the weight of the existing buildings as reaction force to assist the sinking of the caisson; After the reaction beam construction is completed, the caisson is constructed to develop the underground space of the existing building. The caisson can reduce the impact of earth excavation on the existing building. Backfilling after caisson construction can restore the ground morphology of the construction area so that the area can be used normally. At the same time, it protects the caisson and enhances the stability of the entire underground space structure.

[0007] Preferably, the depth of the pull-out piles exceeds the bottom plate elevation of the caisson to be constructed, so that the pull-out piles can be better rooted in the stable soil layer, providing stronger pull-out resistance and supporting force, and effectively preventing the caisson from floating or settling unevenly during construction and use. The design bearing capacity of the pull-out piles must not only meet the requirements of providing pull-out support reaction force for the reaction beam, but also the part of the pull-out piles below the caisson bottom plate provides anti-floating bearing capacity during normal use of the caisson, and the part above the bottom plate meets the bearing capacity of the vertical bearing members (basement columns) in the caisson.

[0008] Preferably, the top of the reaction beam is flush with the outdoor ground, so that work such as pouring of the caisson can be carried out below the ground, and the connection point between the reaction beam and the existing building will not enter the room, thereby minimizing the impact on residents of the existing building.

[0009] Preferably, the specific process of caisson construction is: Excavate the ground between the existing buildings to the bottom elevation of the building foundation to form a working pit for the caisson construction. Excavate to the bottom elevation of the building foundation to form a working pit, which provides sufficient space for the caisson construction, facilitates the subsequent caisson pouring and sinking operations, and can effectively control the impact of the construction on the foundation of the existing building; The pouring construction of the first section of the caisson is carried out, a jack is installed between the top of the first section of the caisson and the reaction beam, earth is excavated in the first section of the caisson, and the jack is used to press the first section of the caisson; After the first section of the caisson is submerged in the bottom of the working pit, the second section of the caisson is constructed above the first section and sunk. The earth in the caisson is continuously excavated and the caisson is continuously extended until the designed elevation of the caisson bottom is reached. A jack is installed between the top of the caisson and the reaction beam, and the top pressure of the jack is used to assist the sinking of the caisson, which can effectively overcome the friction of the soil and other resistances during the sinking process of the caisson and make the caisson sink.

[0010] Preferably, when excavating the working pit, the ground near the existing buildings is retained to facilitate travel for residents of the existing buildings.

[0011] Preferably, a working surface is reserved on the outside of the caisson to be constructed in the working pit to serve as a working space for workers to tie steel bars and formwork and pour concrete for the caisson, thereby facilitating the caisson construction work.

[0012] Preferably, the height of the first section of the caisson is the net height from the reaction beam to the bottom of the working pit minus the height of the jack to be installed, and the bottom of the first section of the caisson is constructed into a blade angle to facilitate the caisson to cut into the soil.

[0013] Preferably, a hanging basket is installed on the reaction beam near the inner side of the outer wall of the caisson to provide a working surface in the caisson after excavation, so as to facilitate subsequent work such as steel bar binding and formwork support.

[0014] Preferably, after the caisson sinks to the designed elevation of the caisson bottom, the caisson is sealed and components are constructed inside the caisson to fully utilize the underground space of the existing building.

[0015] Preferably, when the opposite side of the existing building is an open space, a caisson construction area is set on one side of the existing building, and anti-pullout piles are constructed in the inner area of ​​the caisson to be constructed; After the construction of the pull-out piles is completed, a reaction beam is constructed so that one end of the reaction beam is fixedly connected to the adjacent existing building; the other end of the reaction beam is extended to a set length in the direction away from the caisson to be constructed, and an earth-pile board is constructed on the top of the extended end beam of the reaction beam, and the soil excavated from the caisson is piled on the earth-pile board. The existing building cooperates with the weight of the earth-pile to provide the caisson reaction force, which gives full play to the role of the earth-pile, and in the early stage of the sinking of the caisson, the sinking resistance is small and the amount of earth excavated is small; in the later stage of the sinking of the caisson, the sinking resistance becomes larger, and the amount of earth excavated at this time becomes larger, which can effectively combine the characteristics of the caisson process and reduce costs.

[0016] It can be seen from the above technical solutions that the advantages of the present invention are: 1. Anti-pullout piles are set in the caisson, which can not only serve as supports for reaction beams, improve the stress state of reaction beams, and reduce the cross-section of reaction beams, but also in areas with high groundwater levels, the anti-pullout piles at the bottom of the caisson can be used as anti-floating components of the caisson. The anti-pullout piles in the caisson can be used as part of the columns of the basement, effectively reducing the cost. Compared with those set near the outer wall of the caisson, the anti-pullout piles set in the caisson have higher bearing capacity and can better play their role. In addition, the two ends of the reaction beam are fixedly connected to the existing building, using the weight of the existing building as a reaction force, which plays a better role in assisting the sinking of the caisson.

[0017] 2. The depth of the pull-out pile exceeds the elevation of the bottom plate of the caisson to be constructed, so that the pull-out pile can be better rooted in the stable soil layer, providing stronger pull-out resistance and supporting force, and effectively preventing the caisson from floating or settling unevenly during construction and use. The design bearing capacity of the pull-out pile must not only meet the support reaction force for the reaction beam to resist pull-out, but also the part of the pull-out pile below the bottom plate of the caisson provides the anti-floating bearing capacity during normal use of the caisson, and the part above the bottom plate meets the bearing capacity of the vertical bearing components (basement columns) in the caisson.

[0018] 3. The top of the reaction beam is flush with the outdoor ground, so that the pouring of the caisson and other works can be carried out below the ground, and the connection point between the reaction beam and the existing building will not enter the room, thereby minimizing the impact on residents of the existing building. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the foundation and wall plan before adding underground space between strip foundation buildings; Figure 2 It is a schematic diagram of the foundation and wall elevations before adding underground space between strip-based buildings; Figure 3 It is a plan view of the construction of pull-out piles in the area between strip foundation buildings; Figure 4 It is a schematic elevation diagram of the construction of pull-out piles in the area between strip foundation buildings; Figure 5 It is a plan view of constructing reaction beams between strip foundation buildings and excavating earth to the foundation bottom elevation; Figure 6 It is a schematic elevation diagram of constructing reaction beams between strip foundation buildings and excavating earth to the foundation bottom elevation; Figure 7 It is a plan view of pouring the first section of caisson and installing jacks between strip foundation buildings; Figure 8 It is a schematic elevation diagram of pouring the first section of caisson between strip foundation buildings and installing jacks; Fig. 9 It is a plan view of the excavation of earth in the caisson between strip foundation buildings and the gradual sinking of the caisson; Fig.10 It is a schematic elevation diagram of the excavation of earth in the caisson between strip foundation buildings and the gradual sinking of the caisson; Fig.11 It is a schematic elevation diagram of the caisson between strip foundation buildings sunk to the designed elevation; Fig.12 It is a schematic elevation diagram of sealing the bottom of the caisson between strip foundation buildings and constructing the beams and slabs of each floor; Fig.13 It is a plan view of a caisson with soil piled outside a strip foundation building to provide reaction force; Fig.14 It is a schematic elevation diagram of a caisson with soil piled outside a strip foundation building to provide reaction force; Fig.15 It is a plan view of the development of underground space between independent foundation buildings using caissons; Fig.16 It is a schematic elevation diagram of developing underground space using caissons between independent foundation buildings.

[0021] The components represented by the reference numerals in the figure are: 1. Wall; 2. Strip foundation; 3. Outdoor ground; 4. Pull-out piles; 5. Reaction beam; 6. Working pit; 7. Existing earthwork; 8. Jack; 9. First section of caisson; 10. Earthwork in caisson; 11. Second section of caisson; 12. Hanging basket; 13. Design elevation of caisson bottom; 14. Bottom cover; 15. Beam and slab; 16. Top beam and top slab; 17. Earth pile board; 18. Earth pile; 19. Independent foundation; 20. Column. DETAILED DESCRIPTION

[0022] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in this specific embodiment. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0023] Example 1 In a typical embodiment of the present invention, Figure 1-Figure 2As shown in the figure, a method of constructing underground space in the surrounding area of ​​existing buildings by using caisson is proposed, which is as follows: A caisson construction area is set up between existing buildings, and in the inner area of ​​the caisson to be constructed, anti-pullout piles 4 are constructed to serve as mid-span supports for reaction beams 5. Existing buildings are classified into various types, such as Figure 3 and Figure 4 As shown, the strip foundation has an existing building (the upper structure is wall 1); Fig.15 and Fig.16 As shown, there is an existing building with an independent foundation (the superstructure is a column 20).

[0024] Specifically, due to the large distance between the existing buildings, the span of the reaction beam 5 with the existing building foundation as the support at both ends is large, the force is unreasonable, and the cross-sectional size of the reaction beam 5 is also relatively large. Therefore, in the internal area of ​​the caisson to be constructed and on the axis of the reaction beam 5 to be constructed, one or more pull-out piles 4 are set as the mid-span support of the reaction beam 5 according to the span of the reaction beam 5, which can effectively improve the force performance of the reaction beam 5 and reduce its cross-sectional size; in addition, the pull-out piles 4 can also be used as anti-floating components during the use of the caisson, and as vertical support components in the caisson.

[0025] The pull-out pile 4 can be cast on site by means of bored piles or the like. Specifically, the drilling equipment is started, and the drilling construction is carried out according to the pile diameter, pile depth and verticality required by the design. After the drilling reaches the designed depth, the hole is cleaned to remove the sediment at the bottom of the hole and the impurities in the mud to improve the bearing capacity of the pile end. The steel cage is lifted vertically by a crane and slowly placed into the hole to pour concrete. After the concrete pouring is completed, the floating slurry and excess concrete on the pile head are cleaned in time to make the concrete surface of the pile top smooth.

[0026] The depth of the pull-out pile 4 should exceed the bottom plate elevation of the caisson to be constructed (i.e., the design elevation of the caisson bottom is 13), so that the design bearing capacity of the pull-out pile 4 is not only sufficient to provide the pull-out support reaction force for the reaction beam 5, but also the part of the pull-out pile 4 below the caisson bottom plate provides the anti-floating bearing capacity during normal use of the caisson, and the part above the bottom plate meets the bearing capacity of the vertical bearing components (basement columns) in the caisson.

[0027] After the construction of the pull-out piles 4 is completed, the reaction beams 5 are constructed so that the reaction beams 5 are located between the existing buildings to provide a downward pressure reaction force for the sinking of the caisson. The reaction beams 5 are fixedly connected to the pull-out piles 4, and both ends of the reaction beams 5 are fixedly connected to the existing buildings.

[0028] To utilize the weight of existing buildings, such as Figure 5 and Figure 6As shown, when the existing building is a strip foundation existing building, both ends of the reaction beam 5 extend into the wall 1 of the existing building close to the caisson side. Specifically, a hole is opened on the wall 1 perpendicular to the direction of the reaction beam 5, and the tied support steel cage is inserted into the hole. The steel cage of the reaction beam 5 and the support steel cage are tied and connected together, and concrete is poured; at the position of the pull-out pile 4, the longitudinal reinforcement of the pull-out pile 4 should be anchored into the reaction beam 5, and form a whole after the concrete is poured.

[0029] In this embodiment, caissons are used to develop underground space of existing buildings. Caissons can reduce the impact of earth excavation on existing buildings. At the same time, the weight of existing buildings is used as a reaction force to assist the sinking of caissons.

[0030] like Fig.15 and Fig.16 As shown, when the existing building is an existing building with an independent foundation, the reaction beam 5 is arranged on both sides of the column 20 and the pull-out pile 4, and the reaction beam 5 clamps the column 20 and the pull-out pile 4 and fixes and connects them as a whole. Specifically, steel bars are implanted on both sides of the column 20, and the steel bars are extended into the reaction beam 5 at the same time. For the pull-out pile 4, the longitudinal bars of the pull-out pile 4 are bent and anchored into the reaction beams 5 on both sides from both sides, and the reaction beam steel cage is tied, and concrete is poured to form a whole.

[0031] It should be noted that the top of the reaction beam 5 should be flush with the outdoor ground 3, so that the pouring of the caisson and other works can be carried out below the ground, and the connection point between the reaction beam 5 and the existing building will not enter the room, thereby minimizing the impact on residents of the existing building.

[0032] It is understandable that the number of reaction beams 5 needs to be determined comprehensively based on the reaction force required for the sinking of the caisson, the length and width of the caisson cross-section, and the conditions of the wall 1 (or column 20) of the existing building, and no excessive restrictions are made here.

[0033] After the construction of reaction beam 5 is completed, the caisson is constructed.

[0034] Specifically, Figure 6 As shown, the ground between the existing buildings is excavated to the bottom elevation of the building foundation (i.e., the strip foundation 2 or the independent foundation 19) (exceeding the base elevation will affect the safety of the building), forming a working pit 6 for the construction of the caisson, so as to provide sufficient space for the construction of the caisson.

[0035] In order to ensure the travel of residents of existing buildings, the ground within a set distance close to the existing buildings, that is, the existing earthwork 7 close to the existing buildings, is retained. In this embodiment, the ground with a width of 1m close to the existing buildings is retained.

[0036] A working surface of set width is reserved on the outside of the caisson to be constructed in the working pit. In this embodiment, a working surface of about 1m in width is reserved to serve as a working space for workers to tie steel bars, support formwork, and pour concrete for the caisson, thereby facilitating the caisson construction work.

[0037] First, the pouring construction of the first section of the caisson 9 is carried out. Specifically, the steel bars are tied along the edge of the outer wall of the caisson, the formwork is supported, and the concrete is poured. At the top of the caisson, a lap steel bar for connecting the second section of the caisson 11 is reserved. The height of the poured first section of the caisson 9 is the net height from the reaction beam 5 to the bottom of the working pit 6 minus the height of the jack 8 to be installed. Figure 8 As shown, the bottom of the first section of the caisson 9 is constructed into a blade angle to facilitate the caisson to cut into the soil.

[0038] After the wall concrete of the first section caisson 9 reaches the designed strength, a jack 8 is installed between the top of the first section caisson 9 and the reaction beam 5 above it, and then earth is excavated in the first section caisson 9. While excavating earth in the first section caisson 9, the jack 8 is used to press the first section caisson 9, so that the pressing work of the jack 8 is carried out simultaneously with the excavation process. When the piston of the jack 8 completes a stroke, the piston retracts, and a pad of the stroke height is inserted between the jack 8 and the reaction beam 5 to ensure that the jack 8 continues to press down the caisson, and the above operation is repeated until the first section caisson 9 is submerged in the bottom of the working pit 6.

[0039] After the first section of caisson 9 is submerged in the bottom of the working pit 6, continue to tie steel bars, support formwork and pour concrete above the first section of caisson 9, so as to fix the second section of caisson 11 on the top of the first section of caisson 9 to extend the first section of caisson 9. In order to provide a working surface in the caisson after excavation, a hanging basket 12 is installed on the reaction beam 5 near the inner side of the outer wall of the caisson.

[0040] like Figure 10-11 As shown, the earthwork 10 in the caisson is continuously excavated, and the caisson is continuously extended until the designed elevation 13 of the caisson bottom is reached. When there is groundwater within the sinking depth of the caisson, artificial precipitation is required in advance to ensure smooth excavation and sinking.

[0041] like Fig.12 As shown, after the caisson sinks to the designed elevation 13 of the caisson bottom, the caisson is sealed at the bottom 14, and components are constructed in the caisson.

[0042] Specifically, a steel mesh is laid at the bottom of the caisson and concrete is poured to complete the bottom sealing 14 of the caisson. It is particularly important to waterproof the connection between the bottom plate of the caisson and the anti-pulling pile 4. After the bottom sealing 14, precipitation can be stopped. After the bottom sealing is completed, the construction of the beams and slabs 15, top beams and top slabs 16 of each layer in the caisson, as well as the vertical components such as basement columns and walls are gradually completed. The reaction beam 5 can be used as part of the top beam, and the anti-pulling pile 4 can be used as part of the basement column to save costs.

[0043] Finally, the working pit 6 is backfilled to restore the ground.

[0044] In this embodiment, the pull-out piles 4 are arranged in the caisson, which can not only serve as supports for the reaction beams 5, thereby improving the stress state of the reaction beams 5 and reducing the cross-section of the reaction beams 5, but also in areas with high groundwater levels, the pull-out piles 4 at the bottom of the caisson can serve as anti-floating components of the caisson. The pull-out piles 4 in the caisson can be used as partial columns of the basement, effectively reducing the cost. The pull-out piles 4 arranged in the caisson have higher bearing capacity than those arranged near the outer wall of the caisson, and can better play their role.

[0045] Example 2 In another typical embodiment of the present invention, a method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson is proposed. Compared with Example 1, the difference is that the opposite side of the existing building is an open space, and one end of the reaction beam 5 cannot be fixedly connected to the existing building, as follows: A caisson construction area is set up on one side of an existing building, and anti-pullout piles 4 are constructed in the inner area of ​​the caisson to be constructed to serve as the mid-span support of the reaction beam 5. There are many types of existing buildings, such as Figure 3 and Figure 4 As shown, the strip foundation has an existing building (the upper structure is wall 1); Fig.15 and Fig.16 As shown, there is an existing building with an independent foundation (the superstructure is a column 20).

[0046] After the construction of the pull-out pile 4 is completed, Fig.13 and Fig.14 As shown, a reaction beam 5 is constructed so that one end of the reaction beam 5 is fixedly connected to an adjacent existing building, and the other end of the reaction beam 5 is extended by a set length in a direction away from the caisson to be constructed, and an earth pile board 17 is constructed on the top of the extended end beam of the reaction beam 5, and the soil excavated from the caisson is piled on the earth pile board 17, and the weight of the earth pile 18 and the existing building is used to provide a reaction force to ensure the sinking of the caisson, and the reaction beam 5 is fixedly connected to the pull-out pile 4.

[0047] The existing buildings cooperate with the weight of the earth pile 18 to provide the reaction force for the caisson, which gives full play to the role of the earth pile 18. In addition, in the early stage of the caisson sinking, the sinking resistance is small and the amount of earth excavated is small; in the later stage of the caisson sinking, the sinking resistance becomes larger, and the amount of earth excavated at this time becomes larger, which can effectively combine the characteristics of the caisson process and reduce costs.

[0048] It should be noted that the top of the reaction beam 5 should be flush with the outdoor ground 3, so that the pouring of the caisson and other works can be carried out below the ground, and the connection point between the reaction beam 5 and the existing building will not enter the room, thereby minimizing the impact on residents of the existing building.

[0049] After the construction of reaction beam 5 is completed, the caisson is constructed.

[0050] Specifically, the ground between the existing buildings is excavated to the bottom elevation of the building foundation (i.e., the strip foundation 2 or the independent foundation 19) (exceeding the base elevation will affect the safety of the building), forming a working pit 6 for the construction of the caisson, so as to provide sufficient space for the construction of the caisson.

[0051] In order to ensure the travel of residents of existing buildings, the ground within a set distance close to the existing buildings, that is, the existing earthwork 7 close to the existing buildings, is retained. In this embodiment, the ground with a width of 1m close to the existing buildings is retained.

[0052] A working surface of set width is reserved on the outside of the caisson to be constructed in the working pit. In this embodiment, a working surface of about 1m in width is reserved to serve as a working space for workers to tie steel bars, support formwork, and pour concrete for the caisson, thereby facilitating the caisson construction work.

[0053] First, the pouring construction of the first section caisson 9 is carried out. After the wall concrete of the first section caisson 9 reaches the designed strength, the jack 8 is installed between the top of the first section caisson 9 and the reaction beam 5 above it, and then the earth is excavated in the caisson. While excavating the earth in the caisson, the jack 8 is used to press the caisson, so that the pressing work of the jack 8 and the excavation process are carried out simultaneously. After the piston of the jack 8 completes a stroke, the piston retracts, and a cushion block of the stroke height is inserted between the jack 8 and the reaction beam 5 to ensure that the jack 8 continues to press down the caisson, and the above operation is repeated until the first section caisson 9 is submerged in the bottom of the working pit 6.

[0054] After the first section of caisson 9 is submerged in the bottom of the working pit 6, continue to tie steel bars, support formwork and pour concrete above the first section of caisson 9, so as to fix the second section of caisson 11 on the top of the first section of caisson 9 to extend the first section of caisson 9. In order to provide a working surface in the caisson after excavation, a hanging basket 12 is installed on the reaction beam 5 near the inner side of the outer wall of the caisson.

[0055] The earthwork in the caisson is continuously excavated 10, and the caisson is continuously extended until the design elevation 13 of the caisson bottom is reached. After the caisson sinks to the design elevation 13 of the caisson bottom, the bottom of the caisson is sealed 14, and components are constructed in the caisson.

[0056] Specifically, a steel mesh is laid at the bottom of the caisson and concrete is poured to complete the bottom sealing 14 of the caisson. It is particularly important to waterproof the connection between the bottom plate of the caisson and the anti-pulling pile 4. After the bottom sealing 14, precipitation can be stopped. After the bottom sealing is completed, the construction of the beams and slabs 15, top beams and top slabs 16 of each layer in the caisson, as well as the vertical components such as basement columns and walls are gradually completed. The reaction beam 5 can be used as part of the top beam, and the anti-pulling pile 4 can be used as part of the basement column to save costs.

[0057] Finally, the working pit 6 is backfilled to restore the ground.

[0058] 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 method for constructing an underground space in the surrounding area of ​​an existing building using a caisson, characterized in that: The details are as follows: A caisson construction area is set up between existing buildings, and anti-pullout piles (4) are constructed in the inner area of ​​the caisson to be constructed to serve as mid-span supports for the reaction beam (5); Constructing a reaction beam (5) so that the reaction beam (5) is fixedly connected to the pull-out pile (4), and both ends of the reaction beam (5) are fixedly connected to the existing building; After the reaction beam (5) is constructed, the caisson is constructed; Backfill is carried out after the caisson construction is completed.

2. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 1, characterized in that: The depth of the anti-pull pile (4) exceeds the bottom plate elevation of the caisson to be constructed.

3. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 1, characterized in that: The top of the reaction beam (5) is flush with the outdoor ground (3).

4. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 1, characterized in that: The specific process of caisson construction is as follows: Excavating the ground between the existing buildings to the bottom elevation of the building foundation to form a working pit for the construction of the caisson (6); Performing pouring construction of the first section caisson (9), installing a jack (8) between the top of the first section caisson (9) and the reaction beam (5), excavating earth in the first section caisson (9), and simultaneously using the jack (8) to press the first section caisson (9); After the first section caisson (9) is sunk into the bottom of the working pit (6), the second section caisson (11) is constructed above the first section caisson (9) and is sunk, and the earthwork (10) in the caisson is continuously excavated and the caisson is continuously extended until the designed elevation (13) of the caisson bottom is reached.

5. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 4, characterized in that: When excavating the working pit (6), the ground near the existing building is retained.

6. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 4, characterized in that: A working surface is reserved on the outside of the caisson to be constructed in the working pit (6).

7. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 4, characterized in that: The height of the first section caisson (9) is the net height from the reaction beam (5) to the bottom of the working pit (6) minus the height of the jack (8) to be installed, and the bottom of the first section caisson (9) is constructed to form a blade angle.

8. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 4, characterized in that: A hanging basket (12) is installed on the reaction beam (5) at a position close to the inner side of the outer wall of the caisson.

9. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 4, characterized in that: After the caisson sinks to the designed elevation of the caisson bottom (13), the caisson bottom is sealed (14) and components are constructed in the caisson.

10. The method for constructing an underground space in the surrounding area of ​​an existing building by using a caisson according to claim 1, characterized in that: When the opposite side of the existing building is an open space, a caisson construction area is set up on one side of the existing building, and anti-pullout piles (4) are constructed in the inner area of ​​the caisson to be constructed; After the construction of the pull-out piles (4) is completed, a reaction beam (5) is constructed so that one end of the reaction beam (5) is fixedly connected to an adjacent existing building; the other end of the reaction beam (5) is extended by a set length in a direction away from the caisson to be constructed, and an earth pile board (17) is constructed on the top of the extended end beam of the reaction beam (5), and the soil excavated from the caisson is piled on the earth pile board (17).

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