Caisson fixing device and construction method thereof

Abstract

The invention relates to a caisson fixing device and a construction method thereof.The caisson fixing device comprises a caisson body, anchor rods and related structural design, the caisson body is arranged to be an inclined face, the number, the arrangement mode and the interval of the anchor rods are dynamically adjusted according to the water level depth, and reliable connection is achieved through double-layer base plates and nuts; in addition, a grouting pipe and a grouting pipe with a specific hole diameter are arranged for construction cooperation. The purpose of improving the stability and reliability of caisson fixing is achieved, the installation requirements under different water level conditions can be effectively met, the construction process is simplified, and the safety of the overall structure is enhanced.

Description

Technical Field

[0001] This application relates to the field of foundation treatment in civil engineering, and particularly to a caisson fixing device and its construction method. Background Art

[0002] During the building construction process, especially in areas involving groundwater, the underground structure of buildings is not flat and consistent. Common examples are elevator shafts and the elevator areas at the bottom layer of underground garages, where a pit-like structure usually forms. Especially during foundation construction, the foundation depth of these pits is often about 2 meters deeper than that of large-area foundations. When conducting foundation excavation, due to the increased depth, groundwater is often encountered, thus leading to the need for dewatering and water stoppage. The core purpose is to properly handle the impact of groundwater on construction.

[0003] Traditional solutions mainly include overall dewatering and local dewatering. Overall dewatering means lowering the entire groundwater level so that all areas, including local deep pits, meet the construction requirements. However, this method is extremely costly. For every meter of water level reduction, a large amount of manpower, material resources, and financial resources are required. In actual projects, the cost of overall dewatering often reaches millions of yuan, which makes many projects difficult to implement. Another common method is local dewatering, that is, separately treating local deep pits such as elevator shafts and sump pits. Although this method reduces costs to a certain extent, it faces severe challenges in pebble layers. Pebble layers have a high permeability coefficient, which means that the flow rate of groundwater in them is extremely fast and the water inflow is large. It is not only extremely difficult but also costly to pump out the water in the pebble layer to lower the groundwater level. From the perspective of economic and technical feasibility, using the local dewatering method in pebble layers is not ideal, and even in some cases, due to the serious imbalance between input and output, it is not feasible in engineering.

[0004] Existing caisson technologies are mainly used to solve the situation where the height difference h between the groundwater level and the bottom of the sump pit is relatively small, usually h ≤ 1m. In this case, the caisson mainly relies on internal counterweights to resist buoyancy, and then the self-weight of the concrete filled around further strengthens the resistance. However, when h > 1m and the caisson area is large, obvious defects are exposed in the existing technical solutions. On the one hand, the steel plates at the bottom of the caisson will generate tensile forces and upward bulging deformations under the action of huge buoyancy, which may cause the entire caisson box to be damaged and fail. On the other hand, the traditional practice of simply relying on anchor rods distributed around cannot effectively resist this buoyancy. Especially when the caisson area is large, there are no effective anchoring measures in the central area, resulting in a significant reduction in the overall stability of the caisson. Summary of the Invention

[0005] In order to overcome the above problems, this application provides a caisson fixing device and its construction method.

[0006] In a first aspect, a caisson fixing device provided by the present application adopts the following technical solution: A caisson fixing device, comprising: A caisson body, the caisson body being arranged as an inclined plane; Anchor rods, the number of the anchor rods being not less than 8, distributed around and in the central area of the caisson body, the spacing of the anchor rods being adjusted according to the water level depth h, and the calculation formula being 1.2F buoyancy ≤ F anchor force. When the water level depth h = 1m, the anchor rod spacing ≤ 3m; when the water level depth h = 2m, the anchor rod spacing ≤ 2m; when the water level depth h = 3m, the anchor rod spacing ≤ 1.6m; The upper part of each of the anchor rods is processed into a thread and provided with double-layer backing plates, and the anchor rods are fixed to the caisson body through nuts.

[0007] By adopting the above technical solution, anchor rods are arranged around and in the central area of the caisson body, and the spacing of the anchor rods is accurately adjusted according to the water level depth h, effectively dispersing the buoyancy and enhancing the overall stability of the caisson. The connection between the anchor rods and the caisson body through double-layer backing plates and threads not only ensures the firm connection between the caisson and the anchor rods, but also improves the sealing performance of the caisson, effectively preventing groundwater from leaking from the contact part between the anchor rods and the caisson. By precisely controlling the number, position and spacing of the anchor rods, the effective management of the stress state of the caisson is realized, ensuring the safety and reliability of the construction process.

[0008] Preferably, the diameter of the anchor rod is set to 25mm, and the effective depth is set to 4m.

[0009] By adopting the above technical solution, the anchor rod with a diameter of 25mm has high mechanical strength, can provide stronger fixing force under the action of buoyancy, and effectively prevents the caisson from floating. The effective depth of 4m ensures that the anchor rod can penetrate deep into the formation, providing a reliable anchoring point, and can maintain the stability of the caisson even in the case of high groundwater level and large buoyancy. Combined with the connection method of double-layer backing plates and nuts, the sealing performance between the anchor rod and the caisson is further enhanced, effectively preventing groundwater leakage and improving the overall waterproof performance.

[0010] Preferably, the caisson body is welded by steel plates, and the thickness of the steel plates is set to 4mm - 8mm.

[0011] By adopting the above technical solution, the thickness of the steel plates of the caisson body is 4mm - 8mm, which can effectively balance the requirements of light weight and structural strength. The thin steel plates reduce the overall weight of the caisson, reduce the load on the anchor rods, and at the same time retain sufficient rigidity to resist the deformation and displacement caused by buoyancy, improving the anti-floating ability and stability of the caisson.

[0012] Preferably, the inclination angle of the side surface of the caisson body is set to 45° or 60°.

[0013] By adopting the above technical solution, the side of the caisson is designed as an inclined plane of 45 degrees or 60 degrees. To adapt to the slope of the foundation pit, when the foundation pit is more than 1 meter deep, if the excavated foundation pit is dug at 90 degrees, the side wall is prone to collapse, and it is usually dug at 45 degrees or 60 degrees.

[0014] Preferably, 8 grouting pipes are welded to the bottom of the caisson body.

[0015] By adopting the above technical solution, 8 grouting pipes are welded to the bottom of the caisson body, which can effectively fill the gap between the caisson and the formation, improve the density and stability of the soil mass, enhance the friction between the caisson and the formation, and further improve the anti-floating capacity of the caisson. At the same time, the grouting process can also ensure the sealing of the caisson, prevent groundwater from seeping in, and ensure the construction quality and safety.

[0016] Preferably, a hole with a diameter of 30 mm is opened on the caisson body, and the anchor rod passes through it to fix the caisson body.

[0017] By adopting the above technical solution, a hole with a diameter of 30 mm is accurately opened on the caisson body for the anchor rod to pass through. This design ensures that the anchor rod can pass through the caisson smoothly, and the gap width is maintained at a small size, which is convenient for subsequent sealing operations. By accurately opening the hole, it is ensured that the anchor rod can be accurately positioned, avoiding misalignment or loosening caused by too large a hole diameter, and improving the reliability of the connection between the caisson and the anchor rod. The small-diameter hole helps to reduce the gap between the anchor rod and the caisson. Combined with the sealing of rubber gaskets and nuts, it effectively prevents water from entering the caisson through the gap, enhancing the overall waterproof effect. The small-diameter hole reduces the weakening of the caisson structure, ensures the overall strength and stiffness of the caisson, enables it to remain stable under the action of buoyancy, and reduces the risk of deformation.

[0018] Preferably, the characteristic value of the tensile force of the anchor rod is 100 kN.

[0019] By adopting the above technical solution, the characteristic value of the tensile force of the anchor rod is set to 100 kN, which significantly enhances the overall anti-floating performance of the caisson device. This design can effectively resist the huge buoyancy force received by the caisson under the condition of high groundwater level, prevent the caisson from floating or deforming, and ensure the stability and safety of the caisson during the construction process. At the same time, this setting also improves the reliability of the connection between the anchor rod and the caisson, further enhancing the structural strength and service life of the entire system.

[0020] Preferably, By adopting the above technical solution, the protruding part of the anchor rod above the water level is 150 mm, and the upper 300 mm of the steel bar is processed into threads, significantly enhancing the connection reliability between the anchor rod and the caisson. This design not only facilitates the alignment and fixation operations in subsequent construction, but also improves the tensile performance of the anchor rod, effectively preventing the floating of the caisson under the action of buoyancy. At the same time, the thread design increases the contact area between the anchor rod and the nut, improves the stability of the connection, and further enhances the overall stability and safety of the caisson.

[0021] Preferably, By adopting the above technical solution, the top of the anchor rod below the middle water level is the same as the top of the anchor rod above the water level, and all the steel bar bodies below 150 mm and above the orifice elevation are processed into threads. This design ensures that the anchor rod can effectively play its role under different water level conditions and is convenient for installation and adjustment during the construction process.

[0022] In the second aspect, a construction method of a caisson fixing device includes the following steps: Drive the anchor rod according to the design coordinates; Excavate the foundation trench according to the outer dimensions of the caisson; Fabricate the caisson body according to the dimensions of the structural design; Precisely measure the actual coordinates of the anchor rod and drill holes on the caisson body; Use a lifting device to lift and align the caisson, and slowly lower the caisson to the predetermined position. At the same time, under the action of buoyancy, water will enter the caisson from the gap between the middle anchor rod body and the caisson, enabling the caisson to slowly sink to the bottom of the trench; Seal the water channels inside and outside the caisson with plugs and nuts; Inject grout into the bottom and side of the caisson through the reserved grouting pipe; Empty the water in the caisson and cut the anchor rod body above the nut in the caisson.

[0023] By adopting the above technical solutions, through a comprehensive anchor bolt distribution strategy, especially by adding anchor bolts in the central area of the caisson, the stability of the caisson is ensured throughout the entire water depth range, effectively resisting the risk of floating and deformation caused by buoyancy. The use of a double-layer backing plate (rubber backing plate at the bottom and steel backing plate at the top) and fixing the anchor bolts to the caisson with nuts greatly enhances the sealing performance of the caisson, effectively preventing groundwater from leaking through the contact part between the anchor bolts and the caisson, and improving the overall waterproof effect. The entire construction method has clear steps and is easy to operate, greatly improving the construction efficiency and project quality. By accurately positioning the anchor bolts and precisely aligning the caisson, the uncertainty and human error during the construction process are reduced, the engineering accident rate is lowered, and the safety and reliability of the construction project are ensured. Compared with the traditional overall dewatering or local dewatering methods, this solution significantly reduces the construction cost through reasonable structural design and construction technology. Especially in the pebble layer, the high dewatering cost is avoided, achieving a balance between economy and technical feasibility.

[0024] In summary, the present application includes at least one of the following beneficial technical effects: 1. The comprehensive anchor bolt distribution strategy and special connection design significantly reduce the deformation risk faced by large-area caissons under high groundwater level conditions, and improve the buoyancy resistance performance of the caissons; 2. The use of double-layer backing plates and threaded steel anchor bolts improves the sealing performance of the caissons, effectively preventing groundwater from leaking through the contact part between the anchor bolts and the caissons, and enhancing the overall waterproof effect; 3. The optimization of the construction process and detail management greatly improves the construction efficiency and project quality, reduces the engineering accident rate, and ensures the safety and reliability of the construction project. Description of the Drawings

[0025] Figure 1 is a schematic structural diagram of a caisson fixing device of the present application.

[0026] Figure 2 is an exploded view of a caisson fixing device of the present application.

[0027] Description of the reference numerals: 1, caisson body; 11, grouting pipe; 2, anchor bolt; 3, double-layer backing plate; 4, foundation trench. Detailed Description of the Embodiment

[0028] The following will Figure 1-2 further describe the present application in detail.

[0029] In the first aspect, an embodiment of the present application discloses a caisson fixing device. Refer to Figure 1, the caisson fixing device includes a caisson body 1 and anchor rods 2. The caisson body 1 is set as an inclined surface to better adapt to the shape of the foundation pit; the number of anchor rods 2 is not less than 8, distributed around and in the central area of the caisson body 1, and the spacing is adjusted according to the water depth h, and the calculation formula is 1.2F buoyancy ≤ F anchor force. Specifically, when the water depth h is 1m, 2m, and 3m respectively, the corresponding maximum allowable spacing of the anchor rods 2 is ≤ 3m, ≤ 2m, and ≤ 1.6m respectively. The upper part of each anchor rod 2 is processed into a thread and equipped with double-layer pads 3, a rubber pad and a steel pad, and the anchor rod 2 is firmly connected to the caisson body 1 through nuts, so as to effectively disperse the buoyancy and enhance the overall stability.

[0030] Specifically, the caisson body 1 is welded by steel plates, and the thickness of the steel plates can be selected within the range of 4mm to 8mm. For example, when the caisson bears a large external pressure, thicker steel plates can be selected to improve the anti-deformation ability; for light application scenarios, thinner plates can be selected to reduce the weight. In addition, the side inclination angle of the caisson body 1 can be selected as 45° or 60° according to the actual working conditions. The former is suitable for ordinary soil environments, and the latter is more suitable for soft soil geological conditions.

[0031] The standard diameter of the anchor rod 2 is 25mm, with sufficient strength to resist the impact of buoyancy; the effective depth is set at 4m to ensure good grip by penetrating deep into the formation; the tensile characteristic value is set at 100kN to meet the high-strength anti-pulling requirements.

[0032] Holes with a diameter of 30mm are provided on the caisson body 1 for the anchor rods 2 to insert. The position accuracy of these holes is crucial and needs to be strictly positioned according to the on-site measurement data to avoid affecting the final assembly effect. To further improve the sealing performance, all anchor rods 2 are equipped with double-layer pads 3. A rubber pad made of a flexible material is used to buffer vibrations, and a hard and wear-resistant top layer is configured as a support skeleton. After installation, a special tool is also required to tighten the nuts to lock the entire set of components and completely eliminate the hidden danger of water leakage.

[0033] Refer to Figure 2 , in addition, 8 grouting pipes 11 are pre-welded at the bottom of the caisson for later grouting of cement mortar to fill the gaps. This measure not only strengthens the foundation bearing capacity but also serves as an anti-seepage barrier. Finally, no matter what the water level height is, any exposed part must be treated against corrosion to serve for a long time.

[0034] In another embodiment, different solutions are set for different types of geological conditions: For the viscous soil area rich in sediment particles, the distance between the anchor rods 2 is increased and the single length is extended, which can penetrate deeper to reach a relatively stable hard rock layer to form a strong support system.

[0035] When facing a loose and easily collapsible gravel area, the distance between the anchor rods 2 is reduced, and the length of each rod is shortened, enabling the rapid establishment of an initial framework outline.

[0036] The implementation principle of the caisson fixing device in the embodiments of the present application is as follows: The caisson body 1 is set as an inclined plane, which can adapt to the slope of the foundation pit to avoid the risk of side wall collapse. The number of anchor rods 2 is not less than 8 and they are distributed around and in the central area of the caisson body 1. Combined with the accurately adjusted spacing of the anchor rods 2 according to the water depth h, the buoyancy is effectively dispersed, enhancing the overall stability of the caisson. The upper part of each anchor rod 2 is processed into a thread and equipped with a double-layer backing plate 3 (the bottom layer is a rubber backing plate, and the upper layer is a steel backing plate), and is firmly connected to the caisson body 1 through nuts, which not only improves the connection strength but also improves the sealing performance of the caisson, effectively preventing groundwater leakage. This design solution comprehensively solves the problems of anti-floating, stability, and waterproofing of the caisson under high groundwater level conditions, significantly improving the construction safety and reliability.

[0037] In the second aspect, the present application provides a construction method for a caisson fixing device, including the following steps: S1, Drive the anchor rods 2 according to the design coordinates. Determine the optimal design plan based on the results of the preliminary investigation to ensure that each anchor rod 2 can accurately fall into the predetermined target area.

[0038] S2, Excavate the foundation trench 4 according to the outer dimensions of the caisson. During this stage, it is necessary to closely monitor the changes in the surrounding environment and adjust the excavation progress in a timely manner to prevent safety accidents.

[0039] S3, Manufacture the caisson body 1 according to the dimensions of the structural design. During the manufacturing process, strict quality control should be carried out, and each link should meet the requirements of national standards and specifications.

[0040] S4, Accurately measure the actual coordinates of the anchor rods 2 and drill holes in the caisson body 1. This work is very meticulous and patient, and it is extremely important and must not be sloppy at all.

[0041] S5, Use a lifting device to lift and align the caisson, and slowly lower the caisson to the predetermined position. During this period, it is necessary to pay attention to observing the amplitude of the water surface fluctuation and make corresponding adjustment actions at any time.

[0042] S6, Seal the water channels inside and outside the caisson.

[0043] S7, Inject grout into the bottom and side of the caisson through the reserved grouting pipe 11. The injected material needs to be prepared in advance with the ratio and concentration well adjusted and stirred evenly before being put into use.

[0044] S8, Drain the water in the caisson and cut off the rod bodies of the anchor rods 2 above the nuts in the caisson. Only then is the full set of processes truly completed. The next step is...

[0045] The implementation principle of the construction method of a fixing device in an embodiment of the present application is as follows: A comprehensive distribution strategy of anchor rods 2 and a special connection design significantly reduce the deformation risk faced by large-area caissons under high groundwater level conditions and improve the buoyancy resistance performance of the caissons; The use of double-layer cushion plates 3 and threaded steel anchor rods 2 improves the sealing performance of the caissons, effectively preventing the leakage of groundwater through the contact part between the anchor rods 2 and the caissons, and enhancing the overall waterproof effect; The optimization of the construction process and detail management greatly improves the construction efficiency and engineering quality, reduces the engineering accident rate, and ensures the safety and reliability of the construction project.

[0046] The above are all preferred embodiments of the present application. The protection scope of the present application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A caisson fixing device, characterized in that: Including: A caisson body (1), the caisson body (1) being arranged as an inclined plane; Anchoring rods (2), the number of the anchoring rods (2) being not less than 8, distributed around and in the central area of the caisson body (1), the spacing of the anchoring rods (2) being adjusted according to the water depth h, and the calculation formula being 1.2F buoyancy ≤ F anchor force. When the water depth h = 1m, the spacing of the anchoring rods (2) ≤ 3m; when the water depth h = 2m, the spacing of the anchoring rods (2) ≤ 2m; when the water depth h = 3m, the spacing of the anchoring rods (2) ≤ 1.6m; The upper part of each anchoring rod (2) is processed into a thread and provided with a double-layer backing plate (3), and the anchoring rod (2) is fixed to the caisson body (1) through a nut.

2. The caisson fixing device according to claim 1, wherein: The diameter of the anchoring rod (2) is set to 25mm, and the effective depth is set to 4m.

3. The caisson fixing device according to claim 1, wherein: The caisson body (1) is welded by steel plates, and the thickness of the steel plates is set to 4mm - 8mm.

4. The caisson fixing device according to claim 1, characterized in that: The side inclination angle of the caisson body (1) is set to 45° or 60°.

5. The caisson fixing device according to claim 4, characterized in that: Eight grouting pipes (11) are welded to the bottom of the caisson body (1).

6. The caisson fixing device according to claim 5, characterized in that: A hole (12) with a diameter of 30mm is opened on the caisson body (1), and the anchoring rod (2) passes through the hole (12) to fix the caisson body (1).

7. The caisson fixing device according to claim 6, characterized in that: The tensile characteristic value of the anchoring rod (2) is 100kN.

8. The caisson fixing device according to claim 7, characterized in that: The protruding part of the anchoring rod above the water level is 150mm, and the upper 300mm of the steel bar is processed into a thread.

9. The caisson fixing device according to claim 7, wherein: The top of the anchoring rod below the middle water level is the same as the top of the anchoring rod above the water level, and all the rod bodies of the steel bars below 150mm and above the orifice elevation are processed into threads.

10. A construction method of a caisson fixing device, which uses the caisson fixing device described in any one of claims 1-9, and is characterized in that: Including the following steps: Driving the anchoring rods (2) according to the design coordinates; Excavating a foundation trench (4) according to the outer dimensions of the caisson; Manufacturing the caisson body (1) according to the dimensions of the structural design; Precisely measuring the actual coordinates of the anchoring rods (2) and opening holes on the caisson body (1); Lifting the caisson by a hoisting device and aligning it, slowly lowering the caisson to a predetermined position. At the same time, under the action of buoyancy, water will enter the caisson from the gap between the rod body of the middle anchoring rod (2) and the caisson (12), so that the caisson can slowly sink to the bottom of the trench; Blocking the water channels inside and outside the caisson with a plug and a nut; Injecting grout into the bottom and side of the caisson through the reserved grouting pipes (11); Draining the water in the caisson and cutting the rod bodies of the anchoring rods (2) above the nuts in the caisson.

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