A pile body transverse top pressure grouting load box and a construction method thereof

Abstract

The present application relates to a kind of pile body transverse top pressure grouting load box and its construction method, load box body is connected with reinforcement cage to form pile body framework, when pile body framework is lowered, concrete is poured, after concrete solidification is completed to form pile body, through the jack in load box body transverse push away pressure plate, drive steel strand loop elongation, positioner detects the push distance of pressure plate, after pressure plate reaches specified stroke, pressure grouting device is pushed away in the space of pressure plate to carry out pressure grouting, finally form post-top pressure grouting spread arm pile.The present application greatly improves the vertical and horizontal bearing capacity of pile foundation.

Description

Technical Field

[0001] This invention relates to a grouting load box for the horizontal top of a pile and its construction method, belonging to the field of application and construction of cast-in-place piles in civil engineering. Background Technology

[0002] Pile foundations are widely used in high-rise buildings, long-span bridges, and other structures, and their bearing capacity directly determines the safety of the superstructure. To ensure absolute safety and reliability, pile foundation bearing capacity designs are often conservative, leading to incalculable waste of human, material, and financial resources. How to effectively improve the bearing capacity of pile foundations while simultaneously reducing pile length and saving costs has been a century-old technical challenge in the field of pile foundations.

[0003] To improve the bearing capacity of pile foundations, there are currently two main methods: one is to change the pile's structural type to increase the pile-soil contact area, such as pile arm piles, bamboo-joint piles, and key piles; the other is to use post-grouting to enhance the engineering properties of the soil around the pile, such as post-grouting and fluid soil. For pile arm piles, bamboo-joint piles, and key piles, changing the end-bearing area transforms a single-end-bearing friction pile into a multi-end-bearing friction pile, thereby altering the pile's stress mechanism and significantly increasing its bearing capacity. However, this requires specialized drilling equipment, and due to construction limitations, the penetration depth is relatively short, and the borehole is prone to collapse during construction, limiting the dimensional expansion and thus restricting its practical application. Using post-grouting on the pile side to treat cast-in-place piles can improve the pile's boundary conditions, enhance the mechanical properties of the soil around the pile, expand the bearing area of ​​the cast-in-place pile, increase its bearing capacity, reduce the need for optimized pile dimensions, and thus improve economic efficiency. However, traditional grouting methods make it difficult to control the fracturing path and penetration area of ​​the grout, and the grout pressure and dosage are uncertain, resulting in instability in the grouting effect. This leads to large fluctuations in the bearing capacity of single piles, making it difficult to guarantee that the bearing capacity of post-grouted piles fully meets design requirements. Therefore, there is an urgent need to propose a method that can effectively improve the bearing capacity of pile foundations while significantly reducing pile length and saving costs. Summary of the Invention

[0004] This invention provides a grouting load box for the horizontal top of a pile and its construction method, which greatly improves the vertical and horizontal bearing capacity of the pile foundation while reducing the cost.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A load cell for grouting the top of a pile includes a load cell body, which includes an upper ring beam, a lower ring beam and several columns. The upper ring beam and the lower ring beam are coaxially arranged and connected by several columns to form a cylindrical cavity frame of the load cell body.

[0007] Several columns divide the circumferential wall of the cylindrical cavity frame into the same number of segments, and each segment is equipped with a pressure plate; the same number of jacks as the pressure plates are installed in the load box body, and the telescopic end of each jack is fixed to the corresponding pressure plate. When the jacks are activated, the pressure plate is pushed outward to the outside of the load box body to form a pile arm.

[0008] A grouting device is installed on the jack. When the bearing plate pushes out of the cylindrical cavity frame of the load box body, the grouting device is activated to press grout into the pile arm.

[0009] As a further preferred embodiment of the present invention, adjacent columns are arranged in parallel, one end of each column is welded and fixed to the upper ring beam, and the other end of the column is welded and fixed to the lower ring beam.

[0010] The height and width of both the upper and lower ring beams range from 3 to 6 cm.

[0011] As a further preferred embodiment of the present invention, a base is installed inside the load cell body, and the bottom ends of several jacks are welded to the base. The telescopic ends of the jacks extend along the radial direction of the load cell body and are fixed to the pressure plate.

[0012] As a further preferred embodiment of the present invention, the pressure plate is curved, and its curvature is the same as that of the circumferential wall of the column cavity frame.

[0013] The structure formed by sequentially splicing several pressure plates matches the circumferential wall of the cylindrical cavity frame;

[0014] As a further preferred embodiment of the present invention, a steel strand box is installed on the lower ring beam of each segment, and several steel strand coils are placed side by side in the steel strand box. One end of the steel strand coil is connected to the inside of the pressure plate facing the jack. When the telescopic end of the jack pushes the pressure plate, the pressure plate drives the steel strand coil to move to the outside of the load box body.

[0015] As a further preferred embodiment of the present invention, a displacement device is installed on the upper ring beam of each segmented area, and the displacement wire of the displacement device is connected to the bearing plate on the inner side facing the jack.

[0016] As a further preferred embodiment of the present invention, the grouting device includes a grouting pipe, which is tied and mounted on a jack by straps;

[0017] One end of the grouting pipe is connected to the grouting equipment located on the ground through a pipe. A grouting plug is fixed on the inside of the pressure plate facing the jack. The other end of the grouting pipe abuts against the grouting plug.

[0018] As a further preferred embodiment of the present invention, the travel of the telescopic end of the jack in the radial direction of the load box body is 0.5-1 times the diameter of the cast-in-place pile;

[0019] The jacking force is greater than or equal to twice the resistance of the pressure plate;

[0020] The construction method for the grouting load box at the top of the pile includes the following steps:

[0021] Step S1: Design the load cell body and reinforcement cage according to the dimensions and bearing capacity requirements of the cast-in-place pile;

[0022] Step S2: Determine the placement point of the load cell body within the reinforcing cage in the pile frame;

[0023] Step S3: Weld the load cell body to the reinforcing cage to form the pile skeleton of the cast-in-place pile;

[0024] Step S4: Lower the pile body frame of the cast-in-place pile to the position of the cast-in-place pile, pour concrete into the pile body frame, and wait for the cast-in-place pile body to be formed.

[0025] Step S5: When the concrete strength of the pile reaches 80% of the design strength, oil is injected into the jack, the jack is started, the telescopic end of the jack pushes open the bearing plate until all the bearing plates are fully deployed, the other end of the grouting pipe separates from the grouting plug, and the grouting pipe grouts into the pile arm.

[0026] Step S6: After the grouting preset value is reached, the grouting pipe stops grouting; the concrete strength in the pile arm is checked and found to be 80% of the design strength, forming a rear-top grouting expanded arm pile.

[0027] By employing the above technical solutions, the present invention has the following beneficial effects compared to the prior art:

[0028] 1. The grouting load box for the horizontal top of the pile provided by the present invention is integrated into the steel cage to form the pile skeleton of the cast-in-place pile, which can reduce the sinking resistance, facilitate construction, save construction time and construction cost, and at the same time greatly improve the horizontal and vertical bearing capacity of the pile foundation.

[0029] 2. The grouting load box for the horizontal top of the pile provided by the present invention does not require special drilling machinery when forming the cast-in-place pile. After the steel cage is lowered, preliminary grouting is carried out. After completion, the bearing plate of the horizontal top load box is unfolded laterally, which avoids the phenomenon of hole collapse during construction and saves project costs.

[0030] 3. The grouting load box for the horizontal top of the pile provided by the present invention presses grout into the pile arm after the bearing plate is pushed out by the jack, which solves the problem that the grout reinforcement area is difficult to control and the grouting effect is poor in the traditional grouting method, resulting in the failure of the bearing capacity of the post-grouting pile to meet the standard.

[0031] 4. During the jacking process of the load box, the soil around the pile arm becomes more compacted. Combined with grouting treatment within the pile arm, this further alters the strength of the pile arm and the soil around it, resulting in a further increase in the bearing capacity of the pile arm and its sides. Because the pile arm is formed by pre-embedded load boxes and jacking later, no auxiliary equipment is required compared to the construction of irregularly shaped piles, significantly reducing construction time and costs. Under the same bearing capacity design requirements, the post-jacking grouting and expansion technology can optimize pile length and save on project costs, breaking the "false proposition" of high bearing capacity and low cost for pile foundations. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Figure 1 This is a schematic diagram of the structure of the load box body in a preferred embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of the load box body before the pile arm is formed in the preferred embodiment provided by the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of the load box body after forming the pile arm in a preferred embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the structure of the load box body inside the pile frame before the pile arm is formed in the preferred embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the structure of the load box body inside the pile frame after forming the pile arm in a preferred embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the cast-in-place pile structure formed by the post-grouting of the present invention;

[0039] Figure 7 This is a diagram illustrating the effect of slurry diffusion during the implementation of this invention.

[0040] In the diagram: 1 is the load box body, 2 is the upper ring beam, 3 is the lower ring beam, 4 is the column, 5 is the bearing plate, 6 is the jack, 7 is the base, 8 is the grouting pipe, 9 is the grouting plug, 10 is the steel strand box, 11 is the steel strand coil, 12 is the displacement device, 13 is the displacement wire, 14 is the rebar cage joint, 15 is the triangular pyramid, 16 is the rebar cage, 16-1 is the vertical bar of the rebar cage, 16-2 is the stirrup of the rebar cage, 17 is the pile body of the cast-in-place pile, 18 is the pile arm, and 19 is the grout diffusion zone. Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings. In the description of this application, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention 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. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of the present invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of the present invention.

[0042] As described in the background section, several typical cast-in-place pile types in the prior art have the following problems when facing complex geological conditions: irregular piles and the need for special equipment for drilling operations make it easy for the hole to collapse during construction, and the increased pile-soil area is limited, which cannot meet various engineering needs; post-grouting technology has instability, which makes the bearing capacity of a single pile fluctuate greatly, making it difficult to ensure that the bearing capacity of the post-grouting pile fully meets the design requirements.

[0043] Based on the above problems, this application firstly provides a grouting load box for the horizontal top of a pile. Figure 1 The diagram shows a load cell body 1, which includes an upper ring beam 2, a lower ring beam 3, and several columns 4. The upper and lower ring beams are coaxially arranged and connected by the columns to form a cylindrical cavity frame of the load cell body. The columns divide the circumference of the cylindrical cavity frame into the same number of segments, each segment having a bearing plate 5. Jacks 6, the same number as the bearing plates, are installed inside the load cell body. The telescopic end of each jack is fixed to the corresponding bearing plate. Activating the jacks pushes the bearing plates outward from the load cell body to form a pile arm 18. The aforementioned load cell body serves as part of the pile frame. During construction, the pile frame is placed inside the pile body without the need for specialized drilling machinery. After the pile frame is in place, concrete is poured. Once the concrete reaches its design strength, the jacks are activated, at which point the bearing plates are pushed out of the load cell body, and the pile arm is initially formed.

[0044] A grouting device is installed on the jack. When the bearing plate pushes out of the cylindrical cavity frame of the load box body, the grouting device is activated to grout the pile arm, eventually forming a rear-top grouting expanded arm pile. Figure 6 It is a pre-formed cast-in-place pile structure. After grouting through the grouting device provided in this application, grouting is performed within the space opened by the bearing plate to form... Figure 7 The grout diffusion zone 19 shown solves the problems of difficulty in controlling the grout reinforcement area and poor grouting effect caused by traditional grouting methods. At the same time, the additional grout diffusion zone can improve the bearing capacity of the pile itself.

[0045] The following describes each structure within the load cell body separately. In the frame of the load cell body, adjacent columns are arranged in parallel. One end of each column is welded and fixed to the upper ring beam, and the other end of the column is welded and fixed to the lower ring beam. In the embodiment, there can be four or six columns, evenly distributed between the upper and lower ring beams. The reason for choosing an even number of columns is to match the number of jacks. When the number of jacks is selected according to the number of columns, the thrust of the jacks can be balanced when the pile arm is formed, so as to ensure the bearing capacity of the cast-in-place pile.

[0046] A base 7 is installed inside the load cell body. The bottom ends of several jacks are welded to the base, and the telescopic ends of the jacks extend along the radial direction of the load cell body and are fixed to the pressure plate. It should be noted that the pressure plate is curved, and its curvature is the same as that of the circumferential wall of the cylindrical cavity frame; the structure formed by the sequential splicing of several pressure plates matches the circumferential wall of the cylindrical cavity frame. Figure 2 This is a view with the bearing plate closed. When it is necessary to form the pile arm, the jacks are activated, and the structure after the bearing plate is pushed open is as follows. Figure 3 As shown. In the preferred embodiment, the height of both the upper and lower ring beams ranges from 3-6cm, and the width ranges from 4-6cm; correspondingly, the thickness of the bearing plate is also within 3-6cm.

[0047] Since the jack pushes open the bearing plate after the initial grouting is completed, in order to offset some of the concrete pressure and maintain the balance of the pile, a steel strand box 10 is installed on the lower ring beam of each segment. Several steel strand coils 11 are placed side-by-side inside the steel strand box. One end of each steel strand coil is connected to the inside of the bearing plate facing the jack. When the telescopic end of the jack pushes the bearing plate, the bearing plate moves the steel strand coils towards the outside of the load cell. In a preferred embodiment, 5-10 steel strand coils are typically placed side-by-side, and their strength is determined based on the actual required load-bearing capacity of the pile arm. The steel strand coils are also positioned at the bottom of the bearing plate, approximately 5 cm from the bottom of the bearing plate.

[0048] The extension range of the pile arm is determined by the extension distance of the jack's telescopic end. To determine the jack's stroke in real time, a displacement device 12 is installed on the upper ring beam of each segment. The displacement wire 13 of the displacement device is connected to the bearing plate on the inner side facing the jack. The jack's stroke can be determined by the distance of the displacement wire. In a preferred embodiment, the stroke of the jack's telescopic end in the radial direction of the load box body is 0.5-1.0 times the diameter of the cast-in-place pile. The jacking force is designed according to the geological survey report, and the jacking force is generally more than twice the resistance of the bearing plate.

[0049] Next is the grouting device, which includes a grouting pipe 8, which is secured to the jack with straps. One end of the grouting pipe is connected to the grouting equipment located on the ground via a pipe. A grouting plug 9 is fixed to the inside of the pressure plate facing the jack, and the other end of the grouting pipe abuts against the grouting plug. When the pressure plate is opened, it will move the grouting plug out of the grouting pipe, thus opening the grouting channel. The grouting plug is designed to prevent clogging of the grouting holes during concrete pouring.

[0050] The pile frame integrates the load cell body into the reinforcing cage 16. The frame structure design reduces the settling resistance. The reinforcing cage is cylindrical. The reinforcing cage includes several parallel vertical reinforcing bars 16-1. From the top to the bottom of the vertical reinforcing bars, several reinforcing cage stirrups 16-2 are sequentially arranged to fix the vertical reinforcing bars. The load cell body is installed in the reinforcing cage inside the cast-in-place pile and at the end position through the reinforcing cage joint 14 to form the pile frame of the cast-in-place pile. Figure 4 This is a structural diagram of the pile frame before the load cell body forms the pile arm, as provided in this application. Figure 5 This is a schematic diagram of the structure of the load box body within the pile frame provided in this application after forming the pile arm.

[0051] Finally, this application also provides a construction method for a grouting load cell for the horizontal top of a pile, specifically including the following steps:

[0052] Step S1: Design the load cell body and reinforcement cage according to the dimensions and bearing capacity requirements of the cast-in-place pile;

[0053] Step S2: Determine the placement point of the load cell body within the reinforcing cage in the pile frame;

[0054] Step S3: Weld the load cell body to the reinforcing cage to form the pile skeleton of the cast-in-place pile;

[0055] Step S4: Lower the pile body 17 frame of the cast-in-place pile to the position of the cast-in-place pile, pour concrete into the pile body frame, and wait for the cast-in-place pile body to be formed.

[0056] Step S5: When the concrete strength of the pile reaches 80% of the design strength, oil is injected into the jack, the jack is started, the telescopic end of the jack pushes open the bearing plate until all the bearing plates are fully deployed, the other end of the grouting pipe separates from the grouting plug, and the grouting pipe grouts into the pile arm.

[0057] Step S6: After the grouting preset value is reached, the grouting pipe stops grouting; the concrete strength in the pile arm is checked and found to be 80% of the design strength, thus forming a cast-in-place pile.

[0058] During construction, since the set value of concrete strength can also be reflected in the temperature, several triangular cones 15 are installed on the inner side of the bearing plate facing the jack to display temperature changes in real time.

[0059] In summary, this application integrates the load cell body into the reinforcing cage, reducing settlement resistance and facilitating construction. It eliminates the need for specialized drilling machinery; after initial grouting of the reinforcing cage, the bearing plate is laterally deployed, reducing the risk of borehole collapse. Using jacks to lift the bearing plate and inject grout into the pile arm solves the problems of uncontrolled grout reinforcement, poor grouting effect, and insufficient bearing capacity of post-grouted piles in traditional grouting methods. This construction method not only significantly saves construction time and costs but also greatly improves the horizontal and vertical bearing capacity of the pile foundation.

[0060] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0061] The meaning of "and / or" as used in this application includes situations where each exists alone or both exist simultaneously.

[0062] The term "connection" as used in this application can mean a direct connection between components or an indirect connection between components through other components.

[0063] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A grouting load box for the horizontal top of a pile, characterized in that: The system includes a load cell body, comprising an upper ring beam, a lower ring beam, and several columns. The upper and lower ring beams are coaxially arranged and connected by the columns to form a cylindrical cavity frame of the load cell body. The columns divide the circumferential wall of the cylindrical cavity frame into an equal number of segments. Each segment is fitted with a curved bearing plate, the curvature of which matches the curvature of the circumferential wall of the cylindrical cavity frame. The bearing plates are sequentially assembled to form a structure that matches the circumferential wall of the cylindrical cavity frame. Jacks, the same number as the bearing plates, are installed inside the load cell body. The telescopic end of each jack is fixed to the corresponding bearing plate. Activating the jacks pushes the bearing plates outward from the load cell body to form pile arms. A grouting device is installed on the jacks. After the bearing plates are pushed out of the cylindrical cavity frame of the load cell body, the grouting device activates to grout into the pile arms. A base is installed inside the load cell body, and the bottom ends of several jacks are welded to the base. The telescopic ends of the jacks extend along the radial direction of the load cell body and are fixed to the pressure plate. A steel strand box is installed on the lower ring beam of each segment. Several steel strand coils are placed side by side in the steel strand box. One end of the steel strand coil is connected to the inside of the pressure plate facing the jack. When the telescopic end of the jack pushes the pressure plate, the pressure plate drives the steel strand coil to move to the outside of the load box body. The grouting device includes a grouting pipe, which is tied to the jack with straps; one end of the grouting pipe is connected to the grouting equipment located on the ground through a pipe, and a grouting plug is fixed on the inside of the pressure plate facing the jack, and the other end of the grouting pipe abuts against the grouting plug.

2. The grouting load box for the horizontal top of the pile as described in claim 1, characterized in that: The adjacent columns are arranged in parallel. One end of each column is welded to the upper ring beam, and the other end of the column is welded to the lower ring beam. The height and width of the upper and lower ring beams are both 3-6cm.

3. The grouting load box for the horizontal top of the pile as described in claim 1, characterized in that: Displacement devices are installed on the upper ring beam of each segment, and the displacement wires of the displacement devices are connected to the bearing plate on the inside of the jack.

4. The grouting load box for the horizontal top of the pile as described in claim 1, characterized in that: The travel of the jack's extension end in the radial direction of the load cell body is 0.5-1.0 times the pile diameter; the jacking force of the jack is greater than or equal to twice the resistance of the bearing plate.

5. The construction method for the grouting load box for the horizontal top of the pile as described in any one of claims 1-4, characterized in that: Specifically, the following steps are included: Step S1: Design the load cell body and reinforcement cage according to the pile size and bearing capacity requirements; Step S2: Determine the placement point of the load cell body within the reinforcing cage in the pile frame; Step S3: Weld the load cell body to the reinforcing cage to form the pile frame; Step S4: After the pile frame is lowered into place, pour concrete into the pile frame and wait for the pile to take shape. Step S5: When the concrete strength of the pile reaches 80% of the design strength, oil is injected into the jack, the jack is started, the telescopic end of the jack pushes open the bearing plate until all the bearing plates are fully deployed, the other end of the grouting pipe separates from the grouting plug, and the grouting pipe grouts into the pile arm. Step S6: After the grouting preset value is reached, the grouting pipe stops grouting; the concrete strength in the pile arm is checked and found to be 80% of the design strength, forming a rear-top grouting expanded arm pile.

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