A prefabricated component production pedestal foundation structure based on soft soil foundation

Abstract

The utility model relates to the technical field of bridge construction, and specifically discloses a prefabricated component production pedestal foundation structure based on a soft soil foundation, which comprises cement mixing piles, a gravel cushion layer, a concrete strip-shaped enlarged foundation and a prefabricated component pedestal, the lower end of the cement mixing piles is embedded in a soft soil layer, the upper end extends above the surface of the soft soil layer, and the cement mixing piles and the soil between the piles jointly constitute a composite foundation, the gravel cushion layer is laid on the top of the cement mixing piles, the concrete strip-shaped enlarged foundation is cast on the top of the gravel cushion layer, the prefabricated component pedestal is arranged on the top of the concrete strip-shaped enlarged foundation, and the load of the prefabricated component pedestal is transmitted to the composite foundation formed by the cement mixing piles and the soil between the piles through the concrete strip-shaped enlarged foundation and the gravel cushion layer, and through the synergistic effect of the multilevel structure, the problem of insufficient bearing capacity of the soft soil foundation is effectively solved, and stable bearing of the prefabricated component pedestal is realized.

Description

Technical Field

[0001] This utility model relates to the field of bridge construction technology, specifically to a precast component production platform foundation structure based on soft soil foundation. Background Technology

[0002] The foundation of the production platform for precast beams, slabs and other components must have sufficient bearing capacity and stability. However, the bearing capacity of the foundation in soft soil areas is low, and the foundation must be reinforced before the platform is constructed.

[0003] The current conventional method is replacement filling, but it still has the following limitations:

[0004] First, it is costly, requiring the excavation and transportation of soft soil and replacement with sand and gravel, resulting in double costs, and it is not suitable for deep soft foundations;

[0005] Second, the construction period is long, the construction process is complex, and it is significantly affected by the weather.

[0006] Third, the risk of settlement is high, and it is difficult to completely remove the silt, which can easily lead to settlement exceeding the standard and increase the risk of cracking of the foundation.

[0007] The purpose of this invention is to provide a foundation structure for a precast component production platform based on soft soil foundation, so as to solve the problems mentioned in the background art. Utility Model Content

[0008] To achieve the above objectives, this utility model provides a foundation structure for a precast component production platform based on soft soil foundation, including cement mixing piles, crushed stone cushion layer, concrete strip enlarged foundation and precast component platform;

[0009] The lower end of the cement mixing pile is buried in the soft soil layer, and the upper end extends to the surface of the soft soil layer. The cement mixing pile and the soil between the piles together form a composite foundation.

[0010] The crushed stone cushion layer is laid on top of the cement mixing pile;

[0011] The concrete strip-shaped enlarged foundation is poured on top of the crushed stone cushion layer;

[0012] The precast component platform is set on top of the concrete strip enlarged foundation. The load of the precast component platform is transferred to the composite foundation composed of cement mixing piles and soil between piles through the concrete strip enlarged foundation and crushed stone cushion layer.

[0013] Through the synergistic effect of multi-level structures, the problem of insufficient bearing capacity of soft soil foundation is effectively solved, and the stable bearing capacity of precast component pedestals is achieved.

[0014] As a further improvement of this utility model, the top surface of the crushed stone cushion layer is higher than the top surface of the cement mixing pile, and the width of the crushed stone cushion layer, the concrete strip enlarged foundation and the cement mixing pile arrangement is greater than the width of the precast component platform to achieve load diffusion. By raising and widening the crushed stone cushion layer, the load diffusion capacity is enhanced and the local settlement of the soft soil foundation is reduced.

[0015] As a further improvement of this utility model, when the precast component platform is provided with a tensioning end, the width of the crushed stone cushion layer at the tensioning end is greater than the width of the precast component platform to disperse the concentrated stress during tensioning. In view of the special stress at the tensioning end, the concentrated stress is effectively dispersed by locally widening the crushed stone cushion layer, thus avoiding foundation deformation during tensioning.

[0016] As a further improvement of this utility model, a plain concrete cushion layer is provided between the concrete strip enlarged foundation and the crushed stone cushion layer. The surface of the plain concrete cushion layer is finished, which can level and isolate the surface. The finishing process improves the interface bonding quality and ensures the uniformity of load transfer.

[0017] As a further improvement of this utility model, the top of the cement mixing pile is provided with an improved backfill layer, which optimizes the stress state at the top of the pile and avoids stress concentration between the pile top and the cushion layer.

[0018] As a further improvement of this utility model, cement mixing piles are arranged at intervals along the length of the precast component platform, and the upper region of the cement mixing piles forms a dense section that has undergone secondary remixing. The interval arrangement and the design of the upper dense section take into account both the load-bearing efficiency and material economy of the cement mixing piles.

[0019] As a further improvement of this utility model, the concrete strip spread foundation is provided with a layered steel mesh, and the steel mesh is provided with stirrups. The two ends of the stirrups are fixedly connected to the upper and lower layers of steel mesh respectively. The combination of the layered steel mesh and the stirrups enhances the structural strength and integrity of the concrete strip spread foundation and resists the bending moment generated by the pedestal load.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] This invention addresses the pain points of low bearing capacity and easy settlement of soft soil foundations. It improves the foundation bearing capacity by constructing a composite foundation with cement mixing piles and soil between piles. It optimizes load diffusion and disperses concentrated tension stress by combining a raised and widened crushed stone cushion layer. Furthermore, it enhances the overall structural integrity by combining a concrete strip enlarged foundation with layered steel mesh and stirrups. This forms a multi-level synergistic force-bearing system, which avoids the problems of high cost, long construction period and high settlement risk of traditional replacement methods. It also provides stable and reliable soft soil foundation support for precast component pedestals, achieving a balance between bearing performance and economy. Attached Figure Description

[0022] Figure 1 This is a front view of the pedestal foundation of this utility model;

[0023] Figure 2 This is a top view of the pedestal foundation of this utility model;

[0024] Figure 3 This utility model Figure 1 AA section diagram of the pedestal foundation;

[0025] Figure 4 This utility model Figure 1 CC section diagram of the pedestal foundation.

[0026] In the diagram: 1. Cement mixing pile; 2. Crushed stone cushion layer; 3. Concrete strip spread foundation; 4. Precast component platform. Detailed Implementation

[0027] To facilitate understanding of this utility model, a more comprehensive description of it will be given below with reference to the accompanying drawings, which show several embodiments of the utility model. However, the utility model can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the disclosure of this utility model more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Please see Figure 1-4 This utility model provides a foundation structure for a precast component production platform based on soft soil foundation, including cement mixing pile 1, crushed stone cushion layer 2, concrete strip enlarged foundation 3 and precast component platform 4.

[0031] The lower end of the cement mixing pile 1 is buried in the soft soil layer, and the upper end extends to the surface of the soft soil layer. The cement mixing pile 1 and the soil between the piles together form a composite foundation.

[0032] The crushed stone cushion layer 2 is laid on top of the cement mixing pile 1;

[0033] The concrete strip enlarged foundation 3 is poured on top of the crushed stone cushion layer 2;

[0034] The precast component platform 4 is set on top of the concrete strip enlarged foundation 3. The load of the precast component platform 4 is transferred through the concrete strip enlarged foundation 3 and the crushed stone cushion layer 2 to the composite foundation formed by the cement mixing pile 1 and the soil between the piles.

[0035] Through the synergistic effect of multi-level structures, the problem of insufficient bearing capacity of soft soil foundation is effectively solved, and the stable bearing capacity of precast component platform 4 is achieved.

[0036] The top surface of the crushed stone cushion layer 2 is higher than the top surface of the cement mixing pile 1, and the width of the crushed stone cushion layer 2, the concrete strip enlarged foundation 3 and the cement mixing pile 1 is greater than the width of the precast component platform 4 to achieve load diffusion. By raising and widening the crushed stone cushion layer 2, the load diffusion capacity is enhanced and the local settlement of the soft soil foundation is reduced.

[0037] When the precast component platform 4 is provided with a tensioning end, the width of the crushed stone cushion layer 2 at the tensioning end is greater than the width of the precast component platform 4 to disperse the concentrated stress during tensioning. In response to the special stress at the tensioning end, the concentrated stress is effectively dispersed by locally widening the crushed stone cushion layer 2, thus avoiding foundation deformation during tensioning.

[0038] A plain concrete cushion layer is provided between the concrete strip enlarged foundation 3 and the crushed stone cushion layer 2. The surface of the plain concrete cushion layer is finished. The plain concrete cushion layer can be leveled and isolated. The finishing treatment improves the interface bonding quality and ensures the uniformity of load transfer.

[0039] The cement mixing pile 1 has an improved backfill layer at the top of the pile. The improved backfill layer optimizes the stress state at the top of the pile and avoids stress concentration between the pile top and the cushion layer.

[0040] Cement mixing piles 1 are arranged at intervals along the length of the precast component platform 4, and the upper part of the cement mixing piles 1 forms a dense section that has been mixed twice. The arrangement at intervals and the design of the upper dense section take into account both the bearing efficiency and material economy of cement mixing piles 1.

[0041] The concrete strip spread foundation 3 is equipped with a layered steel mesh, with stirrups between the steel mesh. The two ends of the stirrups are fixedly connected to the upper and lower layers of steel mesh, respectively. The combination of the layered steel mesh and the stirrups enhances the structural strength and integrity of the concrete strip spread foundation 3 and resists the bending moment generated by the pedestal load.

[0042] In use, a group of cement-mixing piles is first constructed. The lower ends of the cement-mixing piles are buried in the soft soil layer according to the designed pile positions, while the upper ends extend above the surface of the soft soil layer. The top 50cm of the piles is backfilled with soil mixed with the same amount of cement, so that the cement-mixing piles and the soil between the piles together form a composite foundation, providing a load-bearing foundation for subsequent structures. Then, a crushed stone cushion layer 2 is laid on top of the cement-mixing piles. After removing the laitance from the pile tops, 20-40mm diameter crushed stone (mud content <5%) is spread. In densely piled areas at the beam ends, the cushion layer can be thickened or a bidirectional geogrid can be added. The layers are then compacted until fully compacted. With a strength ≥95%, a load diffusion layer is formed. A 5cm thick C30 plain concrete pad (with a smooth surface) is poured on top of the crushed stone pad 2. After it is formed, steel mesh is tied in layers and stirrups are installed (fixed at both ends to the upper and lower layers of steel mesh). After the formwork is erected (to prevent grout leakage at the joints), concrete strip enlarged foundation 3 is poured. After curing for ≥7 days, a rigid bearing layer is formed. Finally, a precast component pedestal 4 is fixed on top of the concrete strip enlarged foundation 3 to complete the complete assembly of "composite foundation - load diffusion layer - rigid bearing layer - pedestal", realizing the coordinated stress of each layer of structure.

[0043] The composite foundation formed by cement mixing piles 1 and the soil between the piles, combined with the steel mesh structure of the concrete strip enlarged foundation 3, significantly improves the bearing capacity of the soft soil foundation. After pile completion, the bearing capacity of the single pile and the composite foundation meets the production load requirements of the precast components, effectively preventing abutment settlement and deformation. The compaction process and thickening / reinforcement design of the crushed stone cushion layer 2 (beam end area) can evenly diffuse the load transferred from the abutment. The plain concrete cushion layer has both leveling and waterproofing functions, ensuring that the load is smoothly transferred from the abutment to the composite foundation and reducing local stress concentration.

[0044] The cement mixing pile 1 full pile remixing process designed for soft soil geology, as well as the adjustable cushion layer thickness and pile length parameters, can adapt to different soft soil foundation conditions and meet the production platform requirements of various precast components.

[0045] Compared to traditional soft soil foundation replacement methods, this method saves a significant amount of earthwork excavation and transportation costs. Standardized construction steps (such as test piles to determine parameters and layered compaction) shorten the construction period, while materials are readily available, reducing the overall project cost.

[0046] The construction steps for a precast component production platform foundation structure based on soft soil foundation are as follows:

[0047] Step 1: Pre-construction preparation

[0048] Collect technical data such as engineering geological reports, powder spraying design pile location maps, and original ground elevation data tables for the construction site; assemble the cement mixing pile construction machinery and conduct trial runs to ensure normal equipment operation.

[0049] Use P42.5 ordinary Portland cement as the curing agent (dry construction), check the cement product certificate and conduct indoor testing, and strictly prohibit the use of damp or lumpy cement; prepare crushed stone with a particle size of 20-40mm (mud content <5%), C30 concrete raw materials, steel bars, stirrups, etc.

[0050] Six test piles were constructed to determine the cement content (reference value 55-65 kg / m) and ensure that the unconfined compressive strength of the core samples taken on site is ≥1.0 MPa. Key construction parameters such as drilling speed, lifting speed, mixing speed, air jet pressure, and powder spraying amount per unit time were determined simultaneously.

[0051] Step Two: Construction of Cement Mixing Piles 1

[0052] Construction layout and drilling rig positioning: Layout the position of each mixing pile according to the design drawings (pile spacing deviation <100mm) and mark it with bamboo stakes; adjust the position of the mixing pile machine according to the pile position to keep the mixing shaft vertical.

[0053] Drilling operation: Start the drilling rig, and drill the drill bit while rotating. Compressed air is sprayed during drilling (without conveying cement). If the formation pressure is low, cement can be sprayed simultaneously. Stop drilling after the drill bit reaches the designed depth.

[0054] Powder spraying and lifting: Pre-spraying powder should begin within 1m before the drill bit reaches the bottom of the pile (spraying must not be interrupted). When lifting the drill, spray cement according to the test pile parameters to ensure that the cement and soil are fully mixed. Stop spraying powder when the drill bit is lifted to 50cm above the ground.

[0055] Remixing and pile top treatment: In soft soil geology, the entire pile needs to be remixed, and the upper 60% area needs to be remixed twice; after remixing, the machine body is moved to the next pile position, and the top 50cm of the pile is backfilled with soil mixed with the same amount of cement.

[0056] Bearing capacity testing: 28 days after pile formation, the bearing capacity of single piles and composite foundations are randomly tested, and they must meet the bearing requirements of the precast component platform 4.

[0057] Step 3: Laying the crushed stone bedding layer 2

[0058] Preliminary treatment and layout: Remove the laitance and loose parts from the top of cement mixing pile 1, and level it to the design elevation; mark the laying range and elevation control points of the cushion layer according to the design thickness (50cm).

[0059] Paving and reinforcement treatment: Pave 20-40mm diameter crushed stone. In dense pile areas at the beam ends, the cushion layer can be appropriately thickened or a two-way geogrid can be added to enhance the local bearing capacity.

[0060] Layered compaction: first static compaction 1-2 times, then vibratory compaction 2-3 times, with the compaction thickness deviation controlled within ±20mm; the compaction degree is tested by sand cone method.

[0061] Step 4: Construction of the concrete spread foundation

[0062] Plain concrete foundation pouring: A 5cm thick C30 plain concrete foundation is poured on top of the crushed stone foundation 2, and the surface is smoothed to serve as a waterproof and leveling layer.

[0063] Reinforcing bar binding and formwork installation: Bind the reinforcing bar mesh in layers according to the design requirements, and set up stirrups (fixed at both ends to the upper and lower layers of reinforcing bar mesh) to prevent the reinforcing bars from being deformed by being stepped on; use steel or wooden formwork to support the formwork, and apply sealing strips to the joints to prevent grout leakage.

[0064] Concrete pouring and curing: Use an immersion vibrator to pour concrete to avoid under-vibration or over-vibration; perform a second finishing before the initial setting of the concrete to prevent cracking; after final setting, cover with geotextile or film and sprinkle with water to keep it moist; curing time ≥7 days.

[0065] Step 5: Installation of precast component pedestal 4

[0066] After the concrete strip enlarged foundation 3 reaches the required strength, the precast component pedestal 4 is fixed on top of it at the designed position to complete the treatment and assembly of the entire foundation structure.

[0067] The present invention has been described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvement made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, shall be within the protection scope of the present invention.

Claims

1. A foundation structure for a precast component production platform based on soft soil foundation, characterized in that: It includes cement mixing piles (1), crushed stone cushion layer (2), concrete strip enlarged foundation (3) and precast component platform (4); The lower end of the cement mixing pile (1) is buried in the soft soil layer, and the upper end extends to the surface of the soft soil layer. The cement mixing pile (1) and the soil between the piles together form a composite foundation. The crushed stone cushion layer (2) is laid on top of the cement mixing pile (1); The concrete strip enlarged foundation (3) is poured on top of the crushed stone cushion layer (2); The precast component platform (4) is set on top of the concrete strip enlarged foundation (3). The load of the precast component platform (4) is transferred through the concrete strip enlarged foundation (3) and the crushed stone cushion layer (2) to the composite foundation formed by the cement mixing pile (1) and the soil between the piles.

2. The foundation structure of a precast component production platform based on soft soil foundation according to claim 1, characterized in that: The top surface of the crushed stone cushion layer (2) is higher than the top surface of the cement mixing pile (1), and the width of the crushed stone cushion layer (2), the concrete strip enlarged foundation (3) and the cement mixing pile (1) is greater than the width of the precast component platform (4) to achieve load diffusion.

3. The foundation structure for a precast component production platform based on soft soil foundation according to claim 1, characterized in that: When the precast component platform (4) is provided with a tensioning end, the width of the crushed stone cushion layer (2) at the tensioning end is greater than the width of the precast component platform (4) to disperse the tensioning concentrated stress.

4. The foundation structure of a precast component production platform based on soft soil foundation according to claim 1, characterized in that: A plain concrete cushion layer is provided between the concrete strip enlarged foundation (3) and the crushed stone cushion layer (2), and the surface of the plain concrete cushion layer is finished.

5. The foundation structure of a precast component production platform based on soft soil foundation according to claim 1, characterized in that: The cement mixing pile (1) has an improved backfill layer at the top of the pile.

6. The foundation structure of a precast component production platform based on soft soil foundation according to claim 1, characterized in that: Cement mixing piles (1) are arranged at intervals along the length of the precast component platform (4), and the upper part of the cement mixing piles (1) forms a dense section that has been remixed twice.

7. The foundation structure for a precast component production platform based on soft soil foundation according to claim 1, characterized in that: The concrete strip enlarged foundation (3) is provided with a layered steel mesh, and there are stirrups between the steel meshes. The two ends of the stirrups are fixedly connected to the upper and lower layers of steel mesh respectively.

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