Combined type post-grouting device for cast-in-situ bored pile

Abstract

The utility model relates to the field of cast-in-situ bored pile post-grouting, and provides a cast-in-situ bored pile composite post-grouting device which comprises an annular hollow steel plate, an annular rubber capsule is installed under the hollow steel plate, and an annular baffle is vertically installed in an inner ring of the annular rubber capsule downwards. The inner side of the hollow steel plate is connected with the upper end of the annular baffle; the grouting device further comprises a grouting pipeline, the grouting pipeline comprises an open grouting pipe and a closed grouting pipe which are symmetrically arranged along the central axis of the annular baffle, grout outlets are formed in the tail ends of the open grouting pipe and the closed grouting pipe, the grout outlet of the open grouting pipe is formed in the hollow annular structure, and the grout outlet of the closed grouting pipe is formed in the hollow annular structure. And a slurry outlet of the closed grouting pipe is arranged in the annular rubber capsule. After the construction of the cast-in-situ bored pile is finished, the respective advantages of open type grouting and closed type grouting can be well exerted through the'open-close-open 'type grouting sequence, the grouting effect is better guaranteed, and the bearing capacity of the cast-in-situ pile is improved.

Description

Technical Field

[0001] This utility model relates to the field of post-grouting of bored piles, and combines the advantages of open and closed grouting to propose a composite post-grouting device for bored piles. Background Technology

[0002] Post-grouting technology refers to the process where, after a period of time has passed since the completion of a cast-in-place pile, cement grout is injected into the soil layer at the pile tip through a grouting pipe pre-installed within the pile body and a connected grouting valve at the pile tip. The grout strengthens the soil at the pile tip by compacting, penetrating, and fracturing the soil and sediment, thereby increasing the ultimate bearing capacity of the single pile and reducing pile top settlement. Because post-grouting technology can eliminate sediment at the pile bottom and reduce pile foundation settlement and deformation, it is widely used in practical engineering.

[0003] However, existing pile-end grouting methods are either single open grouting (no grout storage rubber capsule cavity at the pile bottom) or single closed grouting (with grout storage rubber capsule cavity at the pile bottom). In some strata, open grouting has low controllability of the grout injection area. Under high pressure, the grout may flow randomly along the cracks in sand, soil, and gravel layers, and the injected grout may not necessarily be concentrated at the pile bottom. The grouting pressure and volume are relatively difficult to control. Closed grouting uses capsules at the bottom of the reinforcing cage to compress the soil around the pile end, usually focusing on compaction grouting. In other words, a single grouting method cannot accurately control the grouting area, grouting pressure, and grouting volume during the grouting process, which may lead to poor stability of the grouting effect and large fluctuations in the bearing capacity of a single pile. Utility Model Content

[0004] In order to solve the problem that existing post-grouting technologies cannot accurately control the grouting area, grouting pressure and grouting volume during the grouting process, the purpose of this utility model is to provide a composite post-grouting device for bored piles.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A composite post-grouting device for bored piles includes an annular hollow steel plate. An annular rubber capsule is installed directly below the hollow steel plate. An annular baffle is vertically installed downwards inside the inner ring of the annular rubber capsule. The inner side of the hollow steel plate is connected to the upper end of the annular baffle. The device also includes grouting pipelines, comprising two open grouting pipes and two closed grouting pipes symmetrically arranged along the central axis of the annular baffle. The ends of the open and closed grouting pipes are grout outlets. The grout outlets of the open grouting pipes are located within the hollow annular structure, and the grout outlets of the closed grouting pipes are located within the annular rubber capsule.

[0007] Preferably, the hollow annular structure is formed by combining the annular baffle, the hollow steel plate, and the annular rubber capsule.

[0008] Furthermore, the two open grouting pipes are continuously bent from the upper end of the hollow steel plate and then extend vertically downwards, so that their grout outlets are placed inside the hollow annular structure.

[0009] Furthermore, the two closed-loop grouting pipes extend from the pipes that are horizontally bent along the central axis near the annular baffle into the annular rubber capsule to form a ring, and the grout outlets of the two closed-loop grouting pipes are located inside the annular rubber capsule and are symmetrically distributed.

[0010] Preferably, both the open and closed grouting pipes are equipped with a one-way valve near the grout outlet.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0012] 1. By relying on the pile bottom grouting device and the "open-closed-open" grouting sequence, the movement of grout in the soil is effectively controlled and constrained, realizing the "local, quantitative, and directional" principles of grouting.

[0013] 2. Compared with open grouting, the use of composite post-grouting device ensures the effect of pile end compaction grouting. It can form a cement enlarged head at the pile end, increase the bearing area of ​​the pile end, and compact the strata around the pile bottom.

[0014] 3. Compared with the closed-type grouting integral steel plate capsule, the bottom annular rubber capsule and hollow steel plate allow mud and water to be discharged upward through the hollow annular structure when the reinforcing cage sinks, which facilitates the reinforcing cage to reach the bottom of the hole smoothly. At the same time, the hollow annular structure can also be used for secondary hole cleaning.

[0015] 4. By alternating between open and closed grouting methods, the false tip and dry gravel at the bottom of the pile can be eliminated. At the same time, the grout penetrates and splits the sediment (slag) layer at the bottom of the pile, and the surrounding permeable or cohesive soil layers such as sand and gravel. Calcification and cementation or dendritic cement stone veins are formed in the above-mentioned strata, which can greatly improve the strength and bearing capacity of the strata.

[0016] In summary, this utility model can concentrate the three effects of grout splitting, penetration and compaction at the pile end, and achieve "fixed area, fixed quantity and fixed pressure" of the injected grout through the "open-closed-open" grouting sequence, thus realizing effective control and constraint of the grout. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1This is an elevation view of the present utility model;

[0019] Figure 2 This is a plan view of the present invention.

[0020] Explanation of reference numerals in the attached figures:

[0021] 1- Annular rubber capsule, 21- Closed grouting pipe, 22- Open grouting pipe, 23- One-way valve, 24- Grout outlet, 3- Hollow steel plate, 4- Annular baffle, 5- Hollow annular structure. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] See Figure 1 , Figure 2 The composite post-grouting device for bored piles provided in this embodiment includes an annular hollow steel plate 3. An annular rubber capsule 1 is installed directly below the hollow steel plate 3. An annular baffle 4 is installed vertically downward inside the inner ring of the annular rubber capsule 1. The inner side of the hollow steel plate 3 is connected to the upper end of the annular baffle 4. The annular baffle 4, the hollow steel plate 3, and the annular rubber capsule 1 are combined to form a hollow annular structure 5. The hollow annular structure 5 can effectively prevent the annular rubber capsule 1 from being wrapped by concrete during the construction of bored piles, thereby affecting the effect of closed grouting.

[0024] See Figure 1 , Figure 2 This utility model also includes a grouting pipeline, which includes two open grouting pipes 22 and two closed grouting pipes 21 symmetrically arranged along the central axis of the annular baffle 4. The ends of both the open and closed grouting pipes 22 and 21 are grout outlets 24. The two open grouting pipes 22 are continuously bent from the upper end of the hollow steel plate 3 and extend vertically downwards, placing their grout outlets 24 within the hollow annular structure 5. The two closed grouting pipes 21 are horizontally bent from the pipeline near the central axis of the annular baffle 4 and extend into the annular rubber capsule 1, forming a ring. The grout outlets 24 of the two closed grouting pipes 21 are located within the annular rubber capsule 1 and are symmetrically distributed. Furthermore, a one-way valve 23 is installed near the grout outlet 24 of both the open and closed grouting pipes 22.

[0025] The grouting sequence of this invention is as follows: after the cast-in-place pile is constructed and reaches the designed strength, open grouting is performed first, followed by closed grouting, and finally open grouting is performed again. Specifically, during the first open grouting, the grout mixes with the sediment at the pile bottom and flows back up the pile body along the pile bottom to the ground. During this upward flow, the grout fills the area around the pile, improving the pile-soil interaction and increasing the pile's side friction. The second closed grouting causes the annular rubber capsule at the pile bottom to expand, forming an enlarged head, and pushes the grout injected during the first open grouting towards the pile bottom, further mixing the cement grout and sediment. During the second open grouting, the expansion and compaction of the annular rubber capsule blocks the upward flow of the grout, causing the cement grout to split downwards, forming root-like cement grout veins, further increasing the pile bottom bearing capacity. By alternating between open and closed grouting methods, the false tip and dry slag at the bottom of the pile can be eliminated. At the same time, the grout penetrates and splits the sediment (slag) layer at the bottom of the pile, as well as the surrounding permeable strata such as sand and gravel or cohesive soil strata. Calcification and cementation or dendritic cement stone veins are formed in the above strata, which can greatly improve the strength and bearing capacity of the strata.

[0026] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A composite post-grouting device for bored piles, characterized in that, The system includes an annular hollow steel plate, with an annular rubber capsule installed directly below the hollow steel plate. An annular baffle is vertically installed downwards inside the inner ring of the annular rubber capsule, and the inner side of the hollow steel plate is connected to the upper end of the annular baffle. It also includes a grouting pipeline, comprising two open grouting pipes and two closed grouting pipes symmetrically arranged along the central axis of the annular baffle. The ends of the open and closed grouting pipes are grout outlets. The grout outlets of the open grouting pipes are located within the hollow annular structure, and the grout outlets of the closed grouting pipes are located within the annular rubber capsule.

2. The composite post-grouting device for bored piles according to claim 1, characterized in that, The hollow ring structure is formed by the combination of the annular baffle, the hollow steel plate, and the annular rubber capsule.

3. The composite post-grouting device for bored piles according to claim 2, characterized in that, The two open grouting pipes are continuously bent from the upper end of the hollow steel plate and then extended vertically downwards, so that their grout outlets are placed inside the hollow annular structure.

4. The composite post-grouting device for bored piles according to claim 3, characterized in that, The two closed grouting pipes are formed by horizontally bending the pipes along the central axis near the annular baffle and extending into the annular rubber capsule, and the grout outlets of the two closed grouting pipes are located inside the annular rubber capsule and are symmetrically distributed.

5. The composite post-grouting device for bored piles according to claim 4, characterized in that, Both the open and closed grouting pipes are equipped with one-way valves near the grout outlet.

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