Soft capsule grouting expansion pile tip for improving pile end bearing capacity and construction method

Abstract

The invention provides a soft bag grouting expansion pile tip for improving the bearing capacity of a pile end and a construction method. The soft bag grouting expansion pile tip comprises a pile body, a soft bag, a grouting pipe and a pile tip expansion head. After the pile body enters a bearing stratum, slurry is injected into the grouting pipe from the pile top to the pile bottom in a stable-pressure, stable-speed and stable-quantity mode through a high-pressure grouting device; and when the internal pressure reaches a critical value, the piston is opened, the mortar is pushed to quickly extrude and expand the soft bag, and meanwhile, the movable plate is opened, so that the pile end expanding head is formed. According to the pressure grouting principle, the pile end is enlarged, meanwhile, the pile end soil layer is compacted, the compression resistance and uplift bearing capacity of the pile end is greatly improved, and pile settlement is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of building structures, and in particular to a soft bag grouting expansion pile tip for improving the bearing capacity of a pile end and a construction method. Background Art

[0002] Post-grouting technology for precast piles is a technology developed in recent years. It uses the cavity in the middle of precast hollow piles (pipe piles or hollow square piles) to embed grouting pipes, which can greatly improve the bearing capacity of the soil layer at the pile end and near the pile end, thereby greatly improving the bearing capacity of a single pile and reducing pile foundation settlement. However, it has disadvantages such as difficult to control the quality of grouting and long construction time. The technology of ramming carrier piles in precast hollow piles uses the cavity in the pile core for carrier construction, which can also greatly improve the bearing capacity of a single pile and reduce pile foundation settlement. The quality is easy to control, but the construction of the carrier is slow and noisy. Each pile needs 200-300 hammers, and the construction time of each carrier is about 2 hours, which requires more working hours. Summary of the invention

[0003] The purpose of the present invention is to provide a soft bag grouting extension pile tip and a construction method which has a simple structure and is simple to construct, and which can expand the pile head through grouting, thereby improving the bearing capacity of the pile foundation.

[0004] To achieve the above object, the present invention provides a soft bag grouting expansion pile tip for improving the bearing capacity of the pile end, comprising a pile body, a soft bag, a grouting pipe and a pile tip enlargement head;

[0005] The upper end of the soft bag is connected to the bottom of the pile body, and the lower end of the soft bag is connected to the pile tip expansion head; after the grouting pipe passes through the pile body and the soft bag, the bottom of the grouting pipe is connected to the pile tip expansion head through a piston;

[0006] The pile tip enlarger head comprises a pile tip enlarger component which is arranged around the outer circumference of the soft bag.

[0007] Furthermore, the soft bag is in a folded state and compressed between the pile body and the pile tip enlarged head.

[0008] Further, the pile tip enlarged head includes a pile end plate, a movable plate and a pile tip;

[0009] The pile tip is arranged at the bottom of the pile end plate, a plurality of movable plates are arranged around a circle of the soft bag, and one end of the movable plate is connected with the pile end plate through a hinge.

[0010] Furthermore, one end of the piston with a tip is inserted into the grouting pipe, and the other end is fixed to the pile end plate.

[0011] Furthermore, the soft bag is connected to the pile body through a joint steel pipe, one end of the joint steel pipe is welded and fixed to the pile body, and the other end is sealed and connected to the soft bag;

[0012] The other end of the soft bag is sealed and connected to the pile end plate.

[0013] The present invention also proposes a construction method for expanding the pile tip by grouting with a soft bag. After the pile body enters the bearing layer, a high-pressure grouting device is used to inject slurry into the grouting pipe from the top of the pile to the bottom of the pile at a steady pressure, speed and amount. When the internal pressure reaches a critical value, the piston is expanded, pushing the mortar to quickly expand the soft bag and open the movable plate at the same time, thereby forming an enlarged head at the pile end.

[0014] Compared with the prior art, the advantages of the present invention are:

[0015] 1. The present invention uses the principle of pressure grouting to expand the pile end and simultaneously compact the soil layer at the pile end, thereby greatly improving the compressive and tensile bearing capacity of the pile end and reducing pile settlement.

[0016] 2. The device of the present invention only needs grouting during the construction phase, which has a fast construction speed and effectively saves labor.

[0017] 3. The pile tip of the present invention is simple to manufacture, can be mass-produced, and can be reliably connected with the prefabricated hollow pile. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a perspective view of the appearance of the pile tip extended by soft bag grouting at the pile end in an embodiment of the present invention.

[0019] Figure 2 It is a cross-sectional view of the pile tip in the embodiment of the present invention.

[0020] Figure 3 It is a schematic diagram of the soft-bag grouting extension pile tip structure in which the soft-bag is in a folded state in an embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the soft bladder grouting extension pile tip structure in which the soft bladder is in an expanded state according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be further described below.

[0023] like Figure 1 and Figure 2 As shown, the present invention proposes a soft-bag grouting extension pile tip for improving the bearing capacity of the pile end, comprising a pile body 1, a soft bag 4, a grouting pipe 3 and a pile tip enlargement head 5; the pile tip enlargement head 5 comprises a pile end plate, a movable plate 54 and a pile tip 52; the pile tip 52 is arranged at the bottom of the pile end plate, a plurality of movable plates 54 are arranged around a circle of the soft bag 4, and one end of the movable plate 54 is connected to the pile end plate through a hinge 53;

[0024] The upper end of the soft bag 4 is sealed with a joint steel pipe 2, one end of which is welded and fixed to the pile body 1, and the lower end of the soft bag 4 is sealed and connected to the pile end plate. After the grouting pipe 3 passes through the pile body 1 and the soft bag 4, the bottom of the grouting pipe 3 is connected to the pile tip expansion head through a piston 51; one end of the piston 51 with a terminal is inserted into the grouting pipe 3, and the other end is fixed to the pile end plate.

[0025] The invention also proposes a construction method, and the pile tip is characterized by: a joint steel pipe 2 is installed at the bottom of the pile body 1, connected to the pile bottom grouting pipe 3, a soft bag 4 is connected to the joint steel pipe and the pile tip enlarged head 5, a piston 51 is arranged on the pile tip enlarged head 5, a pile tip 52 is arranged below, and the periphery of the pile tip enlarged head 5 is connected to a movable plate 54 by a hinge 53. During the construction process, after the pile body enters the bearing layer, a high-pressure grouting device is used to inject slurry 6 into the grouting pipe 3 from the pile top to the pile bottom at a constant pressure, speed and amount. When the internal pressure reaches a critical value, the piston 51 is opened, pushing the mortar to quickly squeeze and expand the soft bag 4, and at the same time opening the movable plate 54, thereby forming a pile end enlarged head.

[0026] In this embodiment, the cross-sectional shape of the pile body 1 can be a circular pipe pile, a hollow bamboo pile, a hollow square pile, a special-shaped hollow square pile, etc.

[0027] In this embodiment, the cross-sectional shape of the joint steel pipe 2 can be cylindrical, truncated cone, etc.

[0028] In this embodiment, the cross-sectional shape of the pile bottom grouting pipe 3 can be cylindrical, truncated cone, conical, etc.

[0029] In this embodiment, the material of the soft bag 4 can be nylon, polyester fiber, polyurethane, polyurethane fabric, polyamide, rubber and the like, preferably a rubber or polymer composite material that is corrosion-resistant, high-pressure-resistant and has good elasticity.

[0030] In this embodiment, the pile tip enlarged head 5 can be circular, square, or polygonal, preferably square.

[0031] In this embodiment, the movable plate 54 can be hingedly connected to the pile tip enlarged head 5 by four steel plates, and the number of the steel plates can be four, three, two, or more, preferably four.

[0032] In this embodiment, the piston 51 may be made of rubber, plastic or other materials, or may be made of steel, but is preferably made of rubber.

[0033] In this embodiment, the slurry 6 material can be cement mortar, fine stone concrete, ordinary concrete, high-strength concrete and other materials.

[0034] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A soft bag grouting pile tip extension for improving the bearing capacity of the pile end, characterized in that: It includes pile body, soft bag, grouting pipe and pile tip expansion head; The upper end of the soft bag is connected to the bottom of the pile body, and the lower end of the soft bag is connected to the pile tip enlarged head; after the grouting pipe passes through the pile body and the soft bag, the bottom of the grouting pipe is connected to the pile tip enlarged head through a piston; The pile tip enlarged head comprises a pile tip enlarged component which is arranged around the outer circumference of the soft bag.

2. The soft bag grouting pile tip extension method for improving the bearing capacity of the pile end according to claim 1 is characterized in that: The soft bag is in a folded state and compressed between the pile body and the pile tip enlarged head.

3. The soft bag grouting pile tip extension method for improving the pile end bearing capacity according to claim 1 is characterized in that: The pile tip enlarged head comprises a pile end plate, a movable plate and a pile tip; The pile tip is arranged at the bottom of the pile end plate, a plurality of movable plates are arranged around a circle of the soft bag, and one end of the movable plate is connected to the pile end plate through a hinge.

4. The soft bag grouting pile tip expansion method for improving the bearing capacity of the pile end according to claim 3 is characterized in that: One end of the piston with a tip is inserted into the grouting pipe, and the other end is fixed to the pile end plate.

5. The soft bag grouting pile tip extension method for improving the pile end bearing capacity according to claim 3 is characterized in that: The soft bag is connected to the pile body through a joint steel pipe, one end of the joint steel pipe is welded and fixed to the pile body, and the other end is sealed and connected to the soft bag; The other end of the soft bag is sealed and connected to the pile end plate.

6. A construction method for extending a pile tip by injection of a soft capsule, using the soft capsule grouting extending pile tip as claimed in any one of claims 1 to 5, characterized in that: After the pile body enters the bearing layer, a high-pressure grouting device is used to inject slurry into the grouting pipe from the top of the pile to the bottom of the pile at a steady pressure, speed and amount; when the internal pressure reaches the critical value, the piston is expanded, pushing the mortar to quickly squeeze and expand the soft bag, and at the same time opening the movable plate to form an enlarged head at the pile end.

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