Deepening of a containment structure based on an original support system

Abstract

The utility model relates to the technical field of foundation pit support technology, and disclose a kind of deepening support structure based on original support system, including existing support structure, the inside of existing support structure is provided with bored pile, multiple are provided around the inside perimeter of existing support structure with equal intervals by bored pile, the top of multiple bored piles is fixedly connected with crown beam, anchor cable is inserted in the inside of crown beam, one end of anchor cable extends into soil layer, the inside of existing support structure is fixedly connected with L type ribbed baffle near top position, the top of L type ribbed baffle is flush with the top of existing support structure.The utility model realizes the efficient reuse of existing support structure, significantly improves engineering economy, by adding bored pile, crown beam, anchor cable and other reinforcing structures in the inside of existing support structure, avoid the abandonment of original support system still with use value, reduce material waste and the cost of re-construction.

Description

Technical Field

[0001] This utility model relates to the field of foundation pit support technology, specifically a deepened support structure based on the original support system. Background Technology

[0002] An excavation pit is a pit dug at the foundation design location according to the base elevation and foundation plan dimensions. Excavation pit retaining structures refer to the supporting structures used to withstand external soil and water pressure during excavation. With the continuous development of urban underground space, the interaction between new underground projects and existing retaining structures has become a common engineering challenge. On the one hand, due to adjustments in construction plans (such as increased excavation depth), some existing retaining structures, while still meeting normal usage requirements in terms of strength, may no longer be suitable for the new working conditions in terms of parameters such as embedment depth. Directly abandoning these structures not only wastes resources but may also interfere with subsequent construction.

[0003] Existing methods have significant limitations: for deep foundation pits, conventional solutions often involve abandoning existing support structures, resulting in idle initial investment; for phased construction projects, due to long construction intervals and unclear underground structural information, there is a lack of targeted technical means for reusing existing retaining structures, often hindering implementation due to stress mismatch or difficulties in construction coordination. These problems not only reduce the economic efficiency of the project but may also cause additional disturbance to the surrounding environment due to secondary construction. Therefore, a technical solution that can safely and efficiently reinforce and reuse existing retaining structures is urgently needed. Utility Model Content

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this utility model provides a deepened retaining structure based on the original support system. It has the advantages of adding a support structure to the original foundation pit retaining structure, thereby utilizing the original retaining structure to reduce costs, and the added support structure can be matched with newly constructed underground projects, thus solving the aforementioned technical problems.

[0005] (II) Technical Solution To achieve the above objectives, this utility model provides the following technical solution: a deepened retaining structure based on the original support system, comprising an existing retaining structure, wherein cast-in-place piles are provided on the inner side of the existing retaining structure, and multiple cast-in-place piles are provided at equal intervals around the inner perimeter of the existing retaining structure, wherein a capping beam is fixedly connected to the top of the multiple cast-in-place piles, and an anchor cable is inserted into the capping beam, one end of the anchor cable extending into the soil layer, wherein an L-shaped ribbed baffle is fixedly connected to the inner side of the existing retaining structure near the top, and the top of the L-shaped ribbed baffle is flush with the top of the existing retaining structure.

[0006] Preferably, the existing retaining structure includes multiple mixing piles distributed around the perimeter of the foundation pit and driven into the soil layer. Multiple seamless steel pipes are inserted into the mixing piles, and a steel mesh is hung on the inner side of the mixing piles. A grouting steel pipe is connected between the steel mesh and the soil layer.

[0007] Preferably, the existing enclosure structure further includes a grid mixing pile reinforcement area, which is fixedly connected to the side of the mixing pile, and a drainage ditch is provided on the top of the grid mixing pile reinforcement area.

[0008] Preferably, a shotcrete structure with inter-pile mesh is provided on the slope of the cast-in-place pile. The shotcrete structure with inter-pile mesh includes a steel mesh laid on the surface of the soil between multiple cast-in-place piles. The steel mesh is fixed in the soil layer by anchor rods, and a concrete layer is sprayed on the surface of the steel mesh. The concrete layer is attached and fixed to the side wall of the cast-in-place pile.

[0009] Preferably, a jet grouting body is provided between the cast-in-place piles. The jet grouting body is formed by high-pressure jet grouting process. Its two ends are respectively connected to the sidewalls of the adjacent cast-in-place piles, and the bottom of the jet grouting body extends to be flush with the embedment depth of the cast-in-place piles, forming a continuous seepage prevention and reinforcement zone.

[0010] Preferably, multiple anchor cables are arranged around the length of the capping beam, with a spacing of 1500-2000mm between adjacent anchor cables. Each anchor cable includes a steel strand and a grouting sleeve. The steel strand passes through the inside of the grouting sleeve, with one end of the steel strand fixedly connected to the capping beam and the other end extending into the soil layer through a drilling process and solidified by grouting the anchoring section. The diameter of the grouting sleeve is 150-180mm, the standard value of the axial tensile force of the steel strand is 200-600kN, and the free section length is 5-8m.

[0011] Compared with the prior art, this utility model provides a deepened enclosure structure based on the original support system, which has the following beneficial effects: 1. This utility model realizes the efficient reuse of existing retaining structures, significantly improving the economic efficiency of the project. By adding reinforced structures such as cast-in-place piles, cap beams, and anchor cables to the inside of the existing retaining structure, the abandonment of the original support system that still has usability is avoided, reducing material waste and reconstruction costs. At the same time, by using L-shaped ribbed baffles to connect the old and new structures to form a synergistic force-bearing system, the load-bearing capacity of the existing structure is fully utilized. There is no need to completely rebuild the support, which greatly reduces the project cost, shortens the construction period, and also reduces the disturbance of secondary construction to the surrounding environment.

[0012] 2. This utility model enhances the stability and adaptability of the foundation pit support system, effectively addressing new working conditions such as increased foundation pit depth. The newly added cast-in-place piles form an integral frame through capping beams, which, together with anchor cables, transfer lateral forces to deeper soil layers, improving the structure's resistance to overturning. The inter-pile mesh spraying and anchoring and the inter-pile jet grouting enhance the integrity and seepage prevention performance of the soil between piles. The grid mixing pile reinforcement zone and drainage ditch further ensure the structure's resistance to deformation and drainage effect. The synergistic work of the new and old structures allows the support system to meet both the original stress requirements and adapt to new situations such as increased foundation pit excavation depth, ensuring safe and stable construction. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the existing enclosure structure in this utility model; Figure 2 This is a schematic diagram of the reinforcing structure added to the existing enclosure structure according to this utility model.

[0014] Among them: 1. Existing retaining structure; 11. Mixing piles; 12. Seamless steel pipes; 13. Reinforced area of ​​grid mixing piles; 14. Grouting steel pipes; 2. Cast-in-place piles; 3. Crown beams; 4. Anchor cables; 5. Soil layers; 6. L-shaped ribbed baffles; 7. Spray jet grouting between piles. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0016] Please see Figures 1-2 A deepened retaining structure based on the original support system includes an existing retaining structure 1. A cast-in-place pile 2 is provided on the inner side of the existing retaining structure 1. Multiple cast-in-place piles 2 are arranged at equal intervals around the inner perimeter of the existing retaining structure 1. A capping beam 3 is fixedly connected to the top of the multiple cast-in-place piles 2. Anchor cables 4 are inserted into the inside of the capping beam 3. One end of the anchor cables 4 extends into the soil layer 5. An L-shaped ribbed baffle 6 is fixedly connected to the inner side of the existing retaining structure 1 near the top. The top of the L-shaped ribbed baffle 6 is flush with the top of the existing retaining structure 1.

[0017] Specifically, the existing retaining structure 1 includes multiple mixing piles 11 distributed around the perimeter of the foundation pit and driven into the soil layer. Multiple seamless steel pipes 12 are inserted into the mixing piles 11. A steel mesh is hung on the inner side of the mixing piles 11. A grouting steel pipe 14 is connected between the steel mesh and the soil layer 5.

[0018] Specifically, the existing retaining structure 1 also includes a grid mixing pile reinforcement area 13, which is fixedly connected to the side of the mixing pile 11, and a drainage ditch is provided on the top of the grid mixing pile reinforcement area 13.

[0019] The advantages are that the existing retaining structure 1, as the core part of the original foundation pit support system, contains multiple mixing piles 11 distributed around the perimeter of the foundation pit and driven into the soil layer 5. These, together with the inserted seamless steel pipes 12, form a basic support skeleton, which can effectively resist external water and soil pressure and maintain the initial stability of the soil around the foundation pit. The steel mesh installed on the inner side works in conjunction with the grouting steel pipes 14 connecting the soil layer 5 to further reinforce the soil between the piles and improve the overall integrity of the soil through grouting, thereby enhancing its seepage prevention capacity. The grid mixing pile reinforcement zone 13 on the side... This provides lateral support to the mixing piles 11, enhancing the overall structure's resistance to deformation. The drainage ditch at the top can promptly drain surface water, preventing water accumulation from putting additional pressure on the retaining structure. Furthermore, when the existing retaining structure 1 is reinforced with new structures, it can transfer the upper load to the new support system by connecting with the inner L-shaped ribbed baffle 6, achieving synergistic stress distribution between the old and new structures. While retaining its original bearing capacity, it provides basic support for new working conditions such as deepening the foundation pit, significantly reducing the cost and construction period of completely rebuilding the support structure.

[0020] Specifically, a shotcrete structure with mesh reinforcement between piles is installed on the slope of the cast-in-place piles 2. The shotcrete structure with mesh reinforcement between piles 2 includes a steel mesh laid on the surface of the soil between multiple cast-in-place piles 2. The steel mesh is fixed in the soil layer 5 by anchor rods, and a concrete layer is sprayed on the surface of the steel mesh. The concrete layer is attached and fixed to the side wall of the cast-in-place piles 2.

[0021] The advantages are that the steel mesh laid on the surface of the soil between multiple cast-in-place piles 2, fixed in the soil layer 5 by anchor rods, can form an integral load-bearing frame covering the area between piles, effectively restraining the lateral deformation of the soil and preventing the loosening and collapse of the soil between piles caused by the excavation of the foundation pit; after the concrete layer sprayed on the surface of the steel mesh is attached and fixed to the side wall of the cast-in-place pile 2, it can not only provide a hard protective layer for the soil between piles to resist the erosion of the soil by the external environment (such as rainwater erosion, weathering, etc.), but also connect adjacent cast-in-place piles 2 into a whole that shares the load, avoiding local damage to a single cast-in-place pile 2 due to concentrated stress; in addition, the structure forms a reliable connection between the surface soil and the deep soil layer 5 through the anchoring effect of the steel mesh and anchor rods, further improving the overall stability of the slope of the cast-in-place pile 2, and together with the cast-in-place piles 2, the capping beam 3 and other structures, it can meet the strength and seepage prevention requirements of the support system under the working conditions of deepening the foundation pit.

[0022] Specifically, a jet grouting body 7 is installed between the cast-in-place piles 2. The jet grouting body 7 is formed by high-pressure jet grouting process. Its two ends are connected to the side walls of the adjacent cast-in-place piles 2 respectively, and the bottom of the jet grouting body 7 extends to be flush with the embedment depth of the cast-in-place piles 2, forming a continuous seepage prevention and reinforcement zone.

[0023] The advantages are that the jet grouting body 7 formed by the high-pressure jet grouting process is connected to the sidewalls of the adjacent cast-in-place piles 2 at both ends, and extends to the same depth as the embedment of the cast-in-place piles 2, forming a continuous anti-seepage reinforcement zone. This effectively fills the gaps between the cast-in-place piles 2, blocks the path of groundwater seepage along the gaps between the piles, and significantly improves the water-stopping performance of the support system. At the same time, the jet grouting body and the cast-in-place piles 2 form an integral load-bearing structure, enhancing the integrity and shear strength of the soil between the piles. This can work together to resist lateral water and soil pressure and prevent the support structure from becoming unstable due to excessive deformation of the soil between the piles. In addition, the consolidated body formed by the high-pressure jet grouting process is tightly integrated with the cast-in-place piles 2, eliminating the need for additional complex connecting components, simplifying the construction process, and adapting to different geological conditions. This further ensures the safety and stability of the support system under conditions such as pit deepening.

[0024] Specifically, multiple anchor cables 4 are arranged around the length of the capping beam 3, with a spacing of 1500-2000mm between two adjacent anchor cables 4. The anchor cable 4 includes a steel strand and a grouting sleeve. The steel strand is inserted inside the grouting sleeve, and one end of the steel strand is fixedly connected to the capping beam 3. The other end extends into the soil layer 5 through a hole-forming process and is solidified by grouting the anchoring section. The diameter of the grouting sleeve is 150-180mm, the standard value of the axial tensile force of the steel strand 41 is 200-600kN, and the length of the free section is 5-8m.

[0025] The advantages are that multiple anchor cables 4 are set around the length of the capping beam 3 with an adjacent spacing of 1500-2000mm. Combined with steel strands and grouting sleeves with specific parameters, this spacing ensures a uniform and continuous tensile force distribution on the capping beam 3 by the anchor cables 4, avoiding localized stress concentration that could lead to deformation of the capping beam 3 or the cast-in-place pile 2. The steel strands are threaded inside the grouting sleeves, which both protect them from corrosive substances in the soil layer 5 and allow the grouting process in the anchoring section to solidify the steel strands with the deeper soil. Layer 5 is firmly bonded to ensure stable bearing capacity with a standard axial tensile force of 200-600kN; the free section length of 5-8m can adapt to the deformation requirements after the foundation pit is deepened, allowing the steel strands to generate moderate tension under stress to buffer the load. At the same time, through the fixed connection with the cap beam 3, the lateral force borne by the cast-in-place pile 2 is transferred to the stable soil layer 5, realizing the coordinated force bearing of the newly added reinforcement structure and the existing retaining structure 1, greatly improving the overturning resistance and stability of the overall support system, and taking into account both safety and economy.

[0026] During use, the existing retaining structure 1 is first inspected and evaluated to confirm the integrity of components such as the mixing piles 11 and seamless steel pipes 12. Surface debris is cleaned and the installation position of the L-shaped ribbed baffle 6 is located. Subsequently, cast-in-place piles 2 are constructed at the bottom of the first layer of the foundation pit inside the existing retaining structure 1, using equal spacing and ensuring that the pile embedment depth meets the design requirements. After the cast-in-place piles 2 are constructed, a capping beam 3 is poured at its top. Simultaneously, holes are drilled in the capping beam 3 at intervals of 1500-2000mm, and anchor cables 4 are inserted. Grouting is then performed on the anchoring section of the anchor cables 4 through grouting sleeves. To ensure the axial tensile force of the steel strands meets the standard, the slope between the cast-in-place piles 2 is simultaneously constructed with a mesh-hanging shotcrete structure, including the sequential laying of the steel mesh, fixing of the anchor rods, and spraying of the concrete layer, ensuring a tight fit with the sidewalls of the cast-in-place piles 2. For seepage prevention, a high-pressure jet grouting process is used to construct the jet grouting body 7 between the cast-in-place piles 2, ensuring that both ends are connected to the cast-in-place piles 2 and the bottom extends to the embedment depth, forming a continuous seepage-proof zone. Finally, an L-shaped ribbed baffle 6 connects the existing retaining structure 1 with the new support system, completing the construction of a collaborative force-bearing system between the old and new structures.

[0027] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A deepened retaining structure based on the original support system, comprising the existing retaining structure (1), characterized in that: The existing retaining structure (1) is provided with cast-in-place piles (2) on its inner side. Multiple cast-in-place piles (2) are provided at equal intervals around the inner perimeter of the existing retaining structure (1). The top of the multiple cast-in-place piles (2) is fixedly connected to a capping beam (3). Anchor cables (4) are inserted into the inside of the capping beam (3). One end of the anchor cables (4) extends into the soil layer (5). An L-shaped ribbed baffle (6) is fixedly connected to the inner side of the existing retaining structure (1) near the top. The top of the L-shaped ribbed baffle (6) is flush with the top of the existing retaining structure (1).

2. The deepened enclosure structure based on the original support system according to claim 1, characterized in that: The existing retaining structure (1) includes multiple mixing piles (11) distributed around the perimeter of the foundation pit and driven into the soil layer. Multiple seamless steel pipes (12) are inserted into the mixing piles (11). A steel mesh is hung on the inner side of the mixing piles (11). A grouting steel pipe (14) is connected between the steel mesh and the soil layer (5).

3. The deepened enclosure structure based on the original support system according to claim 1, characterized in that: The existing enclosure structure (1) also includes a grid mixing pile reinforcement area (13), which is fixedly connected to the side of the mixing pile (11), and a drainage ditch is provided on the top of the grid mixing pile reinforcement area (13).

4. A deepened retaining structure based on the original support system according to claim 1, characterized in that: The slope of the cast-in-place pile (2) is provided with a pile-to-pile mesh spraying and anchoring structure. The pile-to-pile mesh spraying and anchoring structure includes a steel mesh laid on the surface of the soil between multiple cast-in-place piles (2). The steel mesh is fixed in the soil layer (5) by anchor rods, and a concrete layer is sprayed on the surface of the steel mesh. The concrete layer is attached and fixed to the side wall of the cast-in-place pile (2).

5. A deepened retaining structure based on the original support system according to claim 1, characterized in that: A jet grouting body (7) is provided between the cast-in-place piles (2). The jet grouting body (7) is formed by high-pressure jet grouting process. Its two ends are connected to the side walls of the adjacent cast-in-place piles (2), and the bottom of the jet grouting body (7) extends to be flush with the embedment depth of the cast-in-place piles (2), forming a continuous seepage prevention and reinforcement zone.

6. A deepened enclosure structure based on the original support system according to claim 1, characterized in that: The anchor cable (4) is provided in multiple ways along the length of the crown beam (3). The distance between two adjacent anchor cables (4) is 1500-2000mm. The anchor cable (4) includes a steel strand and a grouting sleeve. The steel strand is inserted into the grouting sleeve. One end of the steel strand is fixedly connected to the crown beam (3), and the other end is inserted into the soil layer (5) through a hole-forming process and solidified by grouting the anchor section. The diameter of the grouting sleeve is 150-180mm. The standard value of the axial tensile force of the steel strand (41) is 200-600kN, and the length of the free section is 5-8m.

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