Construction method of underground space supporting system of existing building area
By using the drilling and implantation method to form components such as water-stopping support walls and prefabricated cap beams in existing building areas, a non-displacement soil support system is constructed, which solves the problems of large ground disturbance and high noise caused by existing support methods, and achieves green construction effects with low disturbance, low noise, and short cycle.
Patent Information
- Application Number
- CN202511316663.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2025-11-04
AI Technical Summary
Existing support methods cause significant disturbance to the original foundation environment and generate a lot of noise when constructed in existing building areas. This can easily lead to settlement and structural damage to adjacent buildings, and the construction noise also affects residents' lives.
Four continuous closed water-stopping support walls were formed around the existing building area using the drilling and implantation method. Combined with prefabricated cap beams, internal support columns, and prestressed anchor cable system for the foundation pit retaining piles, a non-displacement support system was constructed. Prefabricated piles were implanted through drilling and grouting to form a stable body, reducing construction disturbance and improving support stability.
It enables minimal disturbance construction, reducing disruption to the foundation and surrounding structures of existing buildings, resulting in low noise, short construction period, low cost, compliance with green construction requirements, and improved economic benefits.
Smart Images
Figure CN120889282A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of underground space supporting, in particular to a construction method of an underground space supporting system in an existing building area. BACKGROUND
[0002] With the city entering the stage of stock updating from the stage of incremental expansion, the newly increased construction land available for piecewise development is becoming increasingly exhausted. In sensitive areas such as built residential communities, schools, hospitals and historical blocks, the construction of underground parking garages, storage or equipment rooms under the existing green land or square becomes an important way to alleviate the space contradiction. Such projects generally have the characteristics of high protection level of surrounding buildings, high density of underground pipelines, high sensitivity of residents' environment, narrow operation surface and narrow red line retreat distance. Therefore, the newly increased supporting system should meet the following requirements: bearing the soil and water pressure inside and outside the foundation pit to ensure its stability; limiting the settlement and horizontal displacement of the enclosure structure and surrounding buildings to the millimeter level; shortening the construction period to shorten the interference with ground traffic and residents' life; controlling the comprehensive cost to avoid high urban renewal cost; and meeting the green construction and double carbon requirements in the whole process, with dust, noise, vibration and waste slurry emissions reaching or being better than the existing environmental protection standards.
[0003] At present, the commonly used supporting structure of underground space is still mainly the soil squeezing type supporting process, including static pressure or hammering type steel pipe pile, PHC pipe pile, Larsen steel sheet pile and SMW method. The process flow is as follows: a large pile machine is positioned, a prefabricated pile body is directly squeezed into the original soil body by using a large pile machine, and a crown beam, a waist beam and an internal support or an anchor cable are arranged. This type of supporting process improves the side friction resistance and passive earth pressure through the soil displacement of the pile body to form an enclosure structure, has the advantages of simple process and universal equipment, and has been verified on a large scale in newly built urban areas.
[0004] However, when the above-mentioned soil squeezing type supporting process is implemented in an existing building area, the following disadvantages are difficult to overcome: 1. The original soil is subjected to strong radial extrusion and shearing during the pile body penetration process, which easily causes ground uplift, lateral displacement and rapid increase of excess pore water pressure, and easily leads to uneven settlement of adjacent building foundations, wall cracking and even structural damage. 2. The impact or vibration pile sinking has a large instantaneous noise, which not only causes resident complaints, but also may cause irreversible damage to precision instruments, historical protected buildings and underground pipelines. SUMMARY
[0005] The purpose of the present application is to provide a construction method of an underground space supporting system in an existing building area, which solves the problems of large disturbance to the original foundation environment of existing buildings and large noise in the supporting process of the existing supporting method.
[0006] The technical scheme adopted by the application to solve the technical problems is: A construction method for an underground space support system in an existing building area includes: S1. Around the predetermined underground space, precast piles are driven into the original soil using the drilling method to form four continuous closed water-stopping support walls. The four water-stopping support walls are connected end to end to form a rectangular enclosure structure. S2. Install prefabricated cap beams on the top of each water-stopping support wall and connect the four prefabricated cap beams end to end. S3. Several internal support columns for the foundation pit are constructed in the soil inside the rectangular retaining structure using the drilling and implantation method. S4. After excavating the foundation pit to the installation position of the horizontal inner support beam, fix the horizontal inner support beam to the top of the corresponding inner support column of the foundation pit, and make the two ends of the horizontal inner support beam abut against the inner walls of the two opposite water-stop support walls respectively. S5. Continue excavating the foundation pit and use a prestressed anchor cable system for the foundation pit retaining piles to connect the water-stopping support wall with the soil on the side wall of the foundation pit.
[0007] Furthermore, the construction methods for water-stopping retaining walls include: S1.1 Construct two rows of installation pile holes, hoist the precast piles into the corresponding installation pile holes, and ensure that the top of the precast piles is higher than the predetermined top height of the installation pile holes; S1.2. Grouting is injected into the circumferential gap between the installation pile hole and the precast pile. After curing, a pile position stabilization body is formed, and the top of the pile position stabilization body is flush with the top of the installation pile hole. S1.3. Excavate the soil between the two rows of precast piles. After the excavation is completed, grout is injected. After solidification, a continuous inter-row reinforcement is formed. The top of the inter-row reinforcement is flush with the top of the pile hole.
[0008] Furthermore, in step S1.1, the center distance between any two adjacent pile holes in each row is 2D±Δ; where D is the diameter of the pile hole and Δ is the allowable construction deviation. Between step S1.2 and step S1.3, the following is also included: S1.2.1 Excavate the soil between two adjacent pile holes in each row to form a pile reinforcement hole. Grout is injected into the pile reinforcement hole, and after solidification, a pile reinforcement is formed that connects the two adjacent pile positions. The top of the pile reinforcement is flush with the top of the pile hole.
[0009] Furthermore, the prefabricated cap beam includes a prefabricated concrete beam body and a prefabricated back rib system. The prefabricated concrete beam body is provided with several vertically penetrating cap beam pile holes, which are used to connect prefabricated piles. The installation method for prefabricated cap beams includes: S2.1. Hoist the precast concrete beam to the top of the corresponding water-stop support wall, control the descent of the precast concrete beam, so that each precast pile is inserted into the corresponding cap beam pile hole, until the precast concrete beam is supported on the reinforcement between the pile rows. S2.2 Grouting is performed into the annular gap between the capping beam pile hole and the precast pile, and the grouting material is formed after curing. S2.3 Utilize a precast back bracing system to tighten both sides of the precast concrete beam.
[0010] Furthermore, the precast concrete beam comprises multiple segments arranged along its axial direction, with adjacent segments connected by precast connecting members.
[0011] Furthermore, each precast concrete beam section has internally threaded bolted components embedded within it, and the precast connecting components are connected to the internally threaded bolted components.
[0012] Furthermore, the supporting columns inside the foundation pit include steel structure columns and concrete foundations fixed to the lower end of the steel structure columns. The construction method for the support columns inside the foundation pit includes: constructing column holes in the soil inside the rectangular retaining structure, hoisting the support columns into the corresponding column holes, injecting grout into the annular gap between the column holes and the concrete foundation, and forming a solidified structure after curing.
[0013] Furthermore, the steel structure column comprises multiple segments arranged along its axial direction, with adjacent segments bolted together.
[0014] Furthermore, the horizontal internal support beam of the foundation pit includes a horizontal support beam body, with stress adjustment and force transmission devices and internal support steel waist beam devices connected sequentially to both ends of the horizontal support beam body; the horizontal support beam body is fixed to the top of the corresponding internal support column of the foundation pit, and the internal support steel waist beam device abuts against the inner wall of the water-stop support wall.
[0015] Furthermore, the prestressed anchor cable system for the foundation pit retaining piles includes a horizontally set steel back beam that is tightly attached to the inner wall of the water-stop support wall, a prestressed anchor cable with one end anchored in the soil of the foundation pit side wall and the other end passing through the water-stop support wall and the steel back beam, and a prestressed locking device that is tightly attached to the steel back beam and connected to the end of the prestressed anchor cable.
[0016] The beneficial effects of this application are: The construction method for the underground space support system of existing building areas provided in this application adopts the non-displacement drilling and implantation method for pile placement, realizing micro-disturbance operation and minimizing disturbance to the original foundation and surrounding structure of the existing building; at the same time, it is combined with a fully prefabricated support system, with components prefabricated in the factory and quickly assembled on site, resulting in low construction noise, short cycle, low cost, and recyclable components, further improving green construction and economic benefits. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a structural schematic diagram of the underground space support system for existing building areas provided in the embodiments of this application; Figure 2 yes Figure 1 Enlarged view of part A in the image; Figure 3 yes Figure 1 Enlarged view of part B in the image; Figure 4 This is a schematic diagram of the structure of the pile hole; Figure 5 This is a schematic diagram of the structure for hoisting precast piles into the installation pile hole; Figure 6 yes Figure 5 Enlarged view of section C; Figure 7 This is a structural schematic diagram of the pile verticality adjustment component; Figure 8 This is a schematic diagram of the structure after grouting between the installation pile hole and the precast pile; Figure 9 yes Figure 8 Enlarged view of section D in the middle; Figure 10 This is a partial plan view of the water-stopping support wall; Figure 11 yes Figure 10 Enlarged view of section E in the middle; Figure 12 This is a structural diagram of the water-stop support wall after construction; Figure 13 This is a structural schematic diagram of a precast concrete beam. Figure 14 yes Figure 13 Enlarged view of section F in the middle; Figure 15 This is a schematic diagram of the structure connecting the prefabricated connecting components and the internal thread bolted components; Figure 16 This is a schematic diagram of the supporting columns inside the foundation pit; Figure 17 This is a schematic diagram of the horizontal internal support beam of the foundation pit.
[0019] Figure label: 1-Water-stopping support wall; 11-Precast pile; 111-Outer annular steel wall; 112-Inner annular steel wall; 113-Sandwich reinforced concrete; 12-Pile hole; 13-Pile stabilizing body; 14-Reinforcement between pile rows; 15-Reinforcement between piles; 16-Pile verticality adjustment component; 161-Horizontal positioning rod; 162-Vertical positioning rod; 2- Support columns within the foundation pit; 21- Steel structure columns; 211- Main frame members; 212- Double-ring reinforced structure; 213- Flange; 22- Concrete foundation; 23- Joint structure; 3-Precast cap beam; 31-Precast concrete beam; 311-Cap beam pile hole; 312-Reserved hole; 32-Precast back bracing system; 33-Precast connecting component; 331-First steel plate; 332-Second steel plate; 333-Jointed steel beam; 34-Internal threaded bolted component; 35-Gap filler; 4-Horizontal internal support beam of the foundation pit; 41-Main body of the horizontal support beam; 42-Stress adjustment and force transmission device; 43-Internal support steel wainscoting device; 5-Prestressed anchor cable system for foundation pit retaining piles; 51-Steel back beam; 52-Prestressed anchor cable; 53-Prestressed locking device; 54-Anchor cable duct; 6-Soil on the sidewall of the foundation pit. Detailed Implementation
[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.
[0021] In the description of this application, the terms "upper," "lower," "left," "right," "front," "rear," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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, they should not be construed as limitations on this application. Unless otherwise specified, the above-mentioned orientational descriptions can be flexibly set in actual application, provided that the relative positional relationships shown in the accompanying drawings are satisfied.
[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0023] See Figure 1 This application provides a construction method for an underground space support system in an existing building area, comprising the following steps: S1. Around the predetermined underground space, precast piles 11 are driven into the original soil using the drilling and implantation method to form four continuous closed water-stopping support walls 1. The four water-stopping support walls 1 are connected end to end to form a rectangular enclosure structure.
[0024] Specifically, the designated underground space is located in the green space or plaza of an existing building area. The bored pile method is a non-displacement construction process that involves drilling holes before planting the piles, causing almost zero disturbance to the original foundation during construction. The precast piles 11 can be prefabricated in a factory, ensuring stable and controllable quality and reliable water sealing. In this embodiment, see... Figure 11 The precast pile 11 can be a hollow tube type precast pile with steel wall and reinforced with concrete, which includes an outer annular steel wall 111, an inner annular steel wall 112 concentrically arranged inside the outer annular steel wall 111, and sandwich reinforced concrete 113 filled between the outer annular steel wall 111 and the inner annular steel wall 112.
[0025] By constructing four continuous closed water-stopping support walls 1 along the perimeter of the predetermined underground space within the original soil, the four water-stopping support walls 1 are connected end to end to form a rectangular enclosure structure, serving as an integrated water-stopping barrier to provide safety assurance for subsequent foundation pit operations; at the same time, the four water-stopping support walls 1 are interconnected, with high overall rigidity and strong deformation control capability.
[0026] S2. Install prefabricated cap beams 3 on the top of each water-stopping support wall 1, and connect the four prefabricated cap beams 3 end to end.
[0027] Four prefabricated cap beams 3 are used to connect the tops of the four water-stop support walls 1 into a whole, forming a ring beam effect, which can improve the rigidity and overall stability of the rectangular enclosure structure. The prefabricated cap beams 3 can be prefabricated in the factory in advance, and the factory prefabrication quality is stable and controllable. The on-site installation is efficient, the construction period is short, and they can be reused, reducing costs.
[0028] S3. Several internal support columns 2 are constructed in the soil inside the rectangular retaining structure using the drilling and implantation method.
[0029] By constructing the internal support columns 2 in advance, vertical supports are provided for the horizontal internal support beams 4 in the foundation pit. The internal support columns 2 are constructed using a non-displacement drilling and implantation process, minimizing disturbance to the existing building foundation. The internal support columns 2 can be prefabricated in the factory in advance, ensuring stable and controllable prefabrication quality, high on-site installation efficiency, short construction period, and reusability, thus reducing costs.
[0030] S4. After excavating the foundation pit to the installation position of the horizontal inner support beam 4, fix the horizontal inner support beam 4 to the top of the corresponding inner support column 2, and make the two ends of the horizontal inner support beam 4 abut against the inner walls of the two opposite water-stopping support walls 1 respectively.
[0031] By installing a horizontal internal support beam 4 on top of the supporting column 2 inside the foundation pit, and having both ends of the horizontal internal support beam 4 abut against the inner walls of the two opposing water-stop retaining walls 1, the exposed water-stop retaining walls 1 are supported after the foundation pit is excavated, preventing displacement of the exposed section of the water-stop retaining walls 1 and improving the stability and reliability of the support system. The supporting column 2 inside the foundation pit can be prefabricated in the factory in advance. Factory prefabrication quality is stable and controllable, on-site installation is efficient, construction period is short, and it can be reused, reducing costs.
[0032] S5. Continue excavating the foundation pit and use the foundation pit retaining pile prestressed anchor cable system 5 to connect the water-stopping support wall 1 to the foundation pit side wall soil 6.
[0033] As the foundation pit is excavated downwards, the prestressed anchor cable system 5 of the foundation pit retaining piles connects the water-stopping support wall 1 to the soil 6 on the side wall of the foundation pit, preventing displacement of the water-stopping support wall 1 during the support process and further improving the stability of the water-stopping support wall 1. The prestressed anchor cable system 5 of the foundation pit retaining piles also has the advantages of low disturbance, and the prestress is adjustable, which can adapt to different strata and load changes. It has a low overall cost and can be recycled and reused later, making it environmentally friendly.
[0034] The construction method for the underground space support system of existing building areas provided in this application adopts a non-extrusion drilling and implantation method for pile placement, realizing micro-disturbance operation and minimizing disturbance to the original foundation and surrounding structure of the existing building; at the same time, it is combined with a fully prefabricated support system, with components prefabricated in the factory and quickly assembled on site, resulting in low construction noise, short cycle, low cost, and recyclable components, further improving green construction and economic benefits.
[0035] In some embodiments, see Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12The construction method of the water-stopping support wall 1 includes the following steps: S1.1 Construct two rows of installation pile holes 12, hoist the precast piles 11 into the corresponding installation pile holes 12, and make the top of the precast piles 11 higher than the predetermined top height of the installation pile holes 12.
[0036] Specifically, after the green space or plaza of the existing building area is marked out, specialized vertical drilling equipment such as small tracked rotary drilling rigs with full casing are used to drill holes along the predetermined outer contour of the underground space according to the required pile length and depth, forming two rows of installation pile holes 12. The center distance between two adjacent installation pile holes 12 in each row should be ≥ the diameter of the installation pile hole 12 + the minimum clear distance, and the diameter of each installation pile hole 12 is larger than the outer diameter of the precast pile 11, such as... Figure 4 As shown. In this embodiment, the center distance between any two adjacent pile holes 12 in each row of pile holes 12 is 2D±Δ; where D is the diameter of the pile hole 12 and Δ is the allowable construction deviation.
[0037] After the two rows of installation pile holes 12 are constructed, a truck crane is used to lift the precast piles 11 into the corresponding installation pile holes 12. The pile position is then vertically corrected using the pile position verticality adjustment component 16 to prevent the precast piles 11 from tilting and adhering to the hole wall of the installation pile hole 12, ensuring a uniform gap between the installation pile hole 12 and the precast pile 11. Figure 5 , Figure 6 As shown.
[0038] See Figure 7 The pile verticality adjustment component 16 may include a horizontal positioning rod 161 and a vertically connected vertical positioning rod 162. The vertical positioning rod 162 is cylindrical, and its diameter is equal to the radius of the pile hole 12 minus the radius of the precast pile 11. One end of the horizontal positioning rod 161 has an arc-shaped positioning surface for tightly fitting against the outer surface of the precast pile 11. During operation, at least three pile verticality adjustment components 16 are evenly distributed around the precast pile 11. The arc-shaped positioning surface of the horizontal positioning rod 161 is fitted against the outer surface of the precast pile 11, and the vertical positioning rod 162 is inserted downward between the pile hole 12 and the precast pile 11, with the horizontal positioning rod 161 supported on the ground at the hole opening.
[0039] See Figure 5 , Figure 6 After the precast piles 11 are installed, the top of the precast piles 11 is higher than the top of the pile hole 12 by a predetermined height to facilitate connection with the precast precast cap beam 3. The predetermined height can be equal to the height of the precast precast cap beam 3.
[0040] S1.2 Grouting is injected into the circumferential gap between the installation pile hole 12 and the precast pile 11. After curing, a pile position stabilizing body 13 is formed, and the top of the pile position stabilizing body 13 is flush with the top of the installation pile hole 12.
[0041] For details, see Figure 8 , Figure 9 , Figure 10 , Figure 11 High-pressure directional grouting equipment is used to inject cement mortar of no less than M15 into the circumferential gap between the pile hole 12 and the precast pile 11. The grouting height is flush with the top of the pile hole 12. After the grout solidifies, it forms a pile position stabilizing body 13 that encapsulates the precast pile 11. This pile position stabilizing body 13 can form a high-strength cemented interface between the pile surface and the soil wall of the hole, firmly anchoring the precast pile 11 in the hole and improving the overall rigidity of the pile and soil.
[0042] S1.3. Excavate the soil between the two rows of precast piles 11. After the excavation is completed, grout is injected. After solidification, a continuous pile-row reinforcement 14 is formed. The top of the pile-row reinforcement 14 is flush with the top of the pile hole 12.
[0043] For details, see Figure 10 , Figure 11 Using specialized excavation equipment, the soil between the two rows of precast piles 11 was excavated to the required depth as designed. After excavation, high-pressure jet grouting was used to inject cement mortar of at least M15 between the two rows of precast piles 11. The grouting height was flush with the top of the pile hole 12. After the grout solidified, a continuous inter-pile reinforcement 14 was formed. This inter-pile reinforcement 14 could interlock with the precast piles 11 on both sides and the pile stabilization body 13, forming a continuous and dense underground curtain. This met the water-stopping requirements of water-rich strata without the need for additional water-stopping columns or other water-stopping measures, reducing the risk of leakage. After the four water-stopping support walls 1 were constructed, their structure was as follows: Figure 12 As shown.
[0044] The construction method of the water-stopping support wall 1 provided in this application embodiment has many advantages, such as high construction efficiency and speed, large support rigidity, small deformation, high water-stopping reliability, small disturbance to the surrounding soil, easy quality control, good durability, economical cost and strong site adaptability, by adopting a combination of precast piles 11 and grouting.
[0045] In some embodiments, see Figure 10 , Figure 11 Between steps S1.2 and S1.3, the method further includes: step S1.2.1, excavating the soil between two adjacent pile holes 12 in each row of pile holes 12 to form a pile reinforcement hole, injecting grout into the pile reinforcement hole using high-pressure jet grouting, and after solidification, forming a pile reinforcement 15 that connects two adjacent pile position stabilizers 13, with the top of the pile reinforcement 15 flush with the top of the pile hole 12.
[0046] Correspondingly, the inter-pile reinforcement 15 connects the two adjacent pile position stabilizers 13 into a whole, forming a continuous partition. During the subsequent grouting of the inter-pile reinforcement 14, it plays a role in restricting the disorderly diffusion of grout, improving the grouting density and seepage prevention performance, thereby improving the construction quality of the inter-pile reinforcement 14 and ensuring the overall strength and water-stopping effect of the water-stopping support wall 1.
[0047] In some embodiments, see Figure 3 The prefabricated cap beam 3 includes a prefabricated concrete beam body 31 and a prefabricated back rib system 32. The prefabricated concrete beam body 31 has several vertically penetrating cap beam pile holes 311, which are used to correspondingly connect prefabricated piles 11. The diameter of the cap beam pile holes 311 can be the same as the diameter of the mounting pile holes 12.
[0048] The installation method of the prefabricated cap beam 3 includes the following steps: S2.1. Hoist the precast concrete beam 31 above the corresponding water-stop support wall 1, control the precast concrete beam 31 to fall, so that each precast pile 11 is inserted into the corresponding cap beam pile hole 311, until the precast concrete beam 31 is supported on the pile row reinforcement 14.
[0049] S2.2 Grouting is performed into the annular gap between the capping beam pile hole 311 and the precast pile 11, and after curing, a gap filler 35 is formed. This gap filler 35 is used to fill the gap between the capping beam pile hole 311 and the precast pile 11, eliminate the assembly gap and transfer the load, so that the precast capping beam 3 and the precast pile 11 work together to ensure effective force transmission between them.
[0050] S2.3. The precast back brace system 32 is used to tighten both sides of the precast concrete beam 31. Correspondingly, the precast back brace system 32 enables the overall reinforcement of the precast concrete beam 31, improving its overall rigidity. The precast back brace system 32 may include two horizontally arranged steel back braces tightly attached to both sides of the precast concrete beam 31, several tie rods penetrating the precast concrete beam 31 and the two steel back braces, and fasteners fixed to both ends of the tie rods and respectively abutting against the two steel back braces. The precast concrete beam 31 has several pre-drilled holes 312 for the tie rods to pass through.
[0051] The prefabricated cap beam 3 provided in this application embodiment can be prefabricated in the factory and assembled on site, which has high installation efficiency and can be reused, thus reducing costs.
[0052] In some embodiments, see Figure 13 , Figure 14The precast concrete beam 31 comprises multiple segments arranged along its axial direction, and adjacent segments of the precast concrete beam 31 are connected by precast connecting members 33. Accordingly, by precasting the precast concrete beam 31 into multiple segments along its axial direction and quickly assembling adjacent segments by precast connecting members 33, the weight of a single precast concrete beam 31 can be significantly reduced, thereby reducing transportation and hoisting costs.
[0053] For example, see Figure 14 , Figure 15 The prefabricated connecting component 33 includes a first steel plate 331, two second steel plates 332, and a spliced steel beam 333. The first steel plate 331 can be connected to two adjacent prefabricated concrete beams 31 by bolts. The two second steel plates 332 are respectively located on both sides of the first steel plate 331, and each second steel plate 332 can be connected to two adjacent prefabricated concrete beams 31 by bolts. The spliced steel beam 333 covers the splicing position of the two adjacent prefabricated concrete beams 31 and is connected to the two adjacent prefabricated concrete beams 31 by bolts. The first steel plate 331, the second steel plate 332, and the spliced steel beam 333 are all provided with through holes for bolts to pass through, and the prefabricated connecting component 33 is provided with internal threaded holes for bolt threaded connection.
[0054] For example, see Figure 15 Each precast concrete beam segment 31 has an internally threaded bolt member 34 pre-embedded within it, and precast connecting members 33 are connected to the internally threaded bolt member 34. For example, the internally threaded bolt member 34 includes a steel frame and several steel pipes welded to the steel frame. The inner wall of the steel pipes has an internally threaded section to form an internally threaded hole for bolt connection. During installation, bolts are used to connect the precast connecting member 33 to the internally threaded bolt member 34.
[0055] In some embodiments, see Figure 16 The supporting columns 2 inside the foundation pit include a steel structure column 21 and a concrete foundation 22 fixed to the lower end of the steel structure column 21.
[0056] The construction method of the support column 2 inside the foundation pit includes: constructing column holes in the soil inside the rectangular retaining structure, hoisting the support column 2 inside the foundation pit into the corresponding column hole, injecting grout into the annular gap between the column hole and the concrete foundation 22, and forming a solidified body 23 after curing.
[0057] Specifically, vertical drilling equipment is used for drilling operations. After drilling, a truck crane is used to lift the support column 2 in the pit into the hole. Then, high-pressure directional jet grouting is used to inject grout into the annular gap between the hole and the concrete foundation 22. After solidification, a solid body 23 is formed, which makes the lower end of the support column 2 in the pit firmly embedded in the foundation soil, thus realizing the installation of the support column 2 in the pit.
[0058] For example, the steel structure column 21 comprises multiple segments arranged along its axial direction, with adjacent segments bolted together. Each segment of the steel structure column 21 may include a main frame 211 consisting of four vertical members, several double-ring reinforcing structures 212 fixed to the main frame 211, and flanges 213 fixed to both ends of the main frame 211. The double-ring reinforcing structure 212 includes an outer ring and an inner ring disposed therein, with the four vertical members disposed between the outer ring and the inner ring and fixedly connected to both the outer ring and the inner ring simultaneously. The flanges 213 between adjacent segments of the steel structure column 21 are fixedly connected by bolts or other fasteners. The lower end of the lowest segment of the steel structure column 21 is embedded in a cylindrical concrete foundation 22.
[0059] In some embodiments, see Figure 17 The horizontal internal support beam 4 of the foundation pit includes a horizontal support beam body 41, and stress adjustment force transmission device 42 and internal support steel waist beam device 43 are connected to the two ends of the horizontal support beam body 41 in sequence. The horizontal support beam body 41 is fixed on the top of the corresponding internal support column 2 of the foundation pit, and the internal support steel waist beam device 43 abuts against the inner wall of the water-stop support wall 1.
[0060] The horizontal support beam 41, the stress adjustment and force transmission device 42, and the internal support steel girder device 43 can all be made of steel materials such as steel profiles and steel plates. They can be connected by fasteners such as bolts, and the connection enables the function of internal support within the foundation pit. The stress adjustment and force transmission device 42 can integrate an intelligent stress sensor to monitor stress changes in the deformation of the water-stop support wall 1 into the foundation pit in real time, thereby assessing the stability of the foundation pit and achieving structural health monitoring.
[0061] In some embodiments, see Figure 2 The prestressed anchor cable system 5 for the foundation pit retaining piles includes a horizontally positioned steel back beam 51 tightly attached to the inner wall of the water-stopping support wall 1, a prestressed anchor cable 52 with one end anchored in the soil 6 of the foundation pit sidewall and the other end passing through the water-stopping support wall 1 and the steel back beam 51, and a prestressed locking device 53 tightly attached to the steel back beam 51 and connected to the end of the prestressed anchor cable 52. Depending on the depth of the foundation pit, the prestressed anchor cable system 5 can have one or more anchor cables; the greater the depth of the foundation pit, the more anchor cables are required.
[0062] Construction method of prestressed anchor cable system 5 for foundation pit retaining piles: First, drill several anchor cable ducts 54 in the water-stopping support wall 1 and the soil 6 of the foundation pit side wall. Insert the prestressed anchor cable 52 into the corresponding anchor cable duct 54. Use high-pressure grouting equipment to inject grout into the anchor cable duct 54. After curing, anchor the prestressed anchor cable 52 in the soil 6 of the foundation pit side wall. Then, attach the steel back beam 51 tightly to the inner wall of the water-stopping support wall 1 and make the prestressed anchor cable 52 pass through the reserved hole of the steel back beam 51. Install the anchor plate and prestressed locking device 53 at the end of the prestressed anchor cable 52 in sequence. Use tensioning equipment to apply the design tension to the prestressed locking device 53 and lock it to complete the anchoring.
[0063] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.
Claims
1. A construction method for an underground space support system in an existing building area, characterized in that, include: S1. Around the predetermined underground space, precast piles (11) are inserted into the original soil using the drilling and implantation method to form four continuous closed water-stopping support walls (1). The four water-stopping support walls (1) are connected end to end to form a rectangular enclosure structure. S2. Install prefabricated cap beams (3) on the top of each of the water-stopping support walls (1) and connect the four prefabricated cap beams (3) end to end. S3. Several foundation pit support columns (2) are constructed in the soil inside the rectangular retaining structure using the drilling and implantation method. S4. After excavating the foundation pit to the installation position of the horizontal inner support beam (4), fix the horizontal inner support beam (4) of the foundation pit to the top of the corresponding inner support column (2) of the foundation pit, and make the two ends of the horizontal inner support beam (4) of the foundation pit abut against the inner walls of the two opposite water-stopping support walls (1). S5. Continue excavating the foundation pit and use the foundation pit retaining pile prestressed anchor cable system (5) to connect the water-stopping support wall (1) to the foundation pit side wall soil (6).
2. The construction method for the underground space support system in existing building areas according to claim 1, characterized in that, The construction method of the water-stopping support wall (1) includes: S1.1 Construct two rows of installation pile holes (12), hoist the precast pile (11) into the corresponding installation pile hole (12), and make the top of the precast pile (11) higher than the top of the installation pile hole (12) by a predetermined height; S1.2 Grouting is injected into the circumferential gap between the installed pile hole (12) and the precast pile (11), and after solidification, a pile position stabilizer (13) is formed, the top of the pile position stabilizer (13) being flush with the top of the installed pile hole (12); S1.
3. Excavate the soil between the two rows of precast piles (11), and after the excavation is completed, grout is injected. After solidification, a continuous pile-row reinforcement (14) is formed, and the top of the pile-row reinforcement (14) is flush with the top of the installed pile hole (12).
3. The construction method for the underground space support system in existing building areas according to claim 2, characterized in that, In step S1.1, the center distance between any two adjacent pile holes (12) in each row of the pile holes (12) is 2D±Δ; where D is the diameter of the pile hole (12) and Δ is the allowable construction deviation. Between step S1.2 and step S1.3, the following is also included: S1.2.1 Excavate the soil between two adjacent pile holes (12) in each row of the installed pile holes (12) to form a pile reinforcement hole, inject grout into the pile reinforcement hole, and after solidification, form a pile reinforcement (15) connecting two adjacent pile position stabilizers (13), with the top of the pile reinforcement (15) flush with the top of the installed pile hole (12).
4. The construction method for the underground space support system in existing building areas according to claim 2, characterized in that, The prefabricated cap beam (3) includes a prefabricated concrete beam body (31) and a prefabricated back rib system (32). The prefabricated concrete beam body (31) is provided with a number of vertically penetrating cap beam pile holes (311), which are used to correspondingly connect the prefabricated piles (11). The installation method of the prefabricated cap beam (3) includes: S2.
1. Hoist the precast concrete beam (31) above the corresponding water-stop support wall (1), control the precast concrete beam (31) to fall, so that each precast pile (11) is inserted into the corresponding cap beam pile hole (311) until the precast concrete beam (31) is supported on the pile row reinforcement (14). S2.2 Grouting is injected into the annular gap between the crown beam pile hole (311) and the precast pile (11), and after solidification, a gap filler (35) is formed. S2.
3. Use the precast back bracing system (32) to tighten both sides of the precast concrete beam (31).
5. The construction method for the underground space support system in existing building areas according to claim 4, characterized in that, The precast concrete beam (31) comprises multiple segments arranged along its axial direction, and adjacent segments of the precast concrete beam (31) are connected by precast connecting members (33).
6. The construction method for the underground space support system in existing building areas according to claim 5, characterized in that, Each precast concrete beam (31) has an internally threaded bolted member (34) embedded in it, and the precast connecting member (33) is connected to the internally threaded bolted member (34).
7. The construction method for the underground space support system in existing building areas according to claim 1, characterized in that, The supporting column (2) in the foundation pit includes a steel structure column (21) and a concrete foundation (22) fixed to the lower end of the steel structure column (21). The construction method of the supporting column (2) in the foundation pit includes: constructing column holes in the soil inside the rectangular retaining structure, hoisting the supporting column (2) in the foundation pit into the corresponding column hole, injecting grout into the annular gap between the column hole and the concrete foundation (22), and forming a solidified body (23) after curing.
8. The construction method for the underground space support system in existing building areas according to claim 7, characterized in that, The steel structure column (21) comprises multiple segments arranged along its axial direction, and adjacent segments of the steel structure column (21) are bolted together.
9. The construction method for the underground space support system in existing building areas according to claim 1, characterized in that, The horizontal inner support beam (4) of the foundation pit includes a horizontal support beam body (41), and the two ends of the horizontal support beam body (41) are respectively connected to a stress adjustment force transmission device (42) and an inner support steel waist beam device (43); the horizontal support beam body (41) is fixed on the top of the corresponding foundation pit inner support column (2), and the inner support steel waist beam device (43) abuts against the inner wall of the water-stop support wall (1).
10. The construction method for the underground space support system in existing building areas according to claim 1, characterized in that, The prestressed anchor cable system (5) for the foundation pit retaining pile includes a horizontally arranged steel back beam (51) that is tightly attached to the inner wall of the water-stopping support wall (1), a prestressed anchor cable (52) that is anchored at one end in the soil (6) of the foundation pit side wall and passes through the water-stopping support wall (1) and the steel back beam (51) in sequence at the other end, and a prestressed locking device (53) that is tightly attached to the steel back beam (51) and connected to the end of the prestressed anchor cable (52).