Prestressed pipe pile post-grouting device and construction method thereof

Abstract

The invention discloses a prestressed pipe pile post-grouting device (100) which comprises a grout outlet steel pipe (3), the pipe wall of the grout outlet steel pipe (3) comprises grout outlet holes (30), and the grout outlet steel pipe (3) is filled with coarse sand (7) for enhancing the rigidity of the grout outlet steel pipe (3). The grain size of the coarse sand (7) is larger than the diameter of the grout outlet holes (3), the coarse sand (7) is prevented from leaking out of the grout outlet holes (30), and the coarse sand (7) is compact in the grout outlet steel pipe (3), so that the coarse sand (7) is used for blocking the grout outlet holes (30) in the pipe wall of the grout outlet steel pipe (3) during pile sinking, and the grout outlet holes (30) in the pipe wall of the grout outlet steel pipe (3) are prevented from being damaged during pile sinking. And the soil body is prevented from being pressed into the slurry outlet steel pipe along with pile sinking in the pile sinking process. According to the method, cement-soil mixing pile construction is not needed, pile bottom post-grouting can be conducted at any time, the absolute construction period is not occupied, and construction is more efficient. And compared with an existing post-grouting device, used materials are reduced, machining is easy, and the installation cost is low.

Description

[0001] This application is a divisional application of the Chinese patent application submitted to the China Patent Office on June 2, 2020, with application number 202010492842.9 and invention name "A prestressed pipe pile post-grouting device and its construction method". Technical Field

[0002] The present invention relates to the field of building construction, and in particular to a prestressed pipe pile post-grouting device and a construction method thereof. Background Art

[0003] Prestressed hollow square piles and prestressed tubular piles are factory-processed and driven by static pressure and hammering. They are characterized by high pile strength, efficient construction, and reliable quality. Because they use high-grade concrete and have high compressive bearing capacity, they are widely used as compression piles in engineering construction. However, due to the relatively weak bonding between the pile body and the soft soil layer, the foundation bearing capacity in many projects is far less than the pile body strength, resulting in a waste of resources. For this reason, engineering technicians urgently need to develop methods to improve the bearing capacity of precast pile foundations. There are two main existing methods: (1) Rigid composite piles: First, cement-soil mixing piles are constructed at the designed pile location, and then the prefabricated pile body is embedded in the cement-soil mixing pile to form a rigid composite pile. This method mainly reinforces the weak soil layer with cement-soil mixing piles in advance, thereby improving the bite force between the pile body and the soil, thereby improving the bearing capacity of the foundation.

[0004] This method has defects that need to be improved: ① It adds a construction link, which reduces construction efficiency; ② The construction of cement-soil mixing piles consumes a large amount of cement, which is expensive; ③ The implantation of prefabricated piles into cement-soil mixing piles will also discharge a large amount of cement soil, which has a great impact on the environment.

[0005] (2) Post-grouting at the pile bottom: This method is inspired by the post-grouting technology used to improve pile foundation bearing capacity. It is more suitable for sites where the soil layer within the pile body is clay, silt, or gravel. It mainly uses a prefabricated pile with a grouting device. After the static pile is driven, post-grouting is carried out at the pile side and pile bottom to improve the foundation bearing capacity.

[0006] This method is mainly applied to prestressed pipe piles. Its key technology is the post-grouting device, which can simultaneously perform post-grouting at the pile bottom and pile side. It mainly consists of a steel pipe with sealing plates at both ends. One end welded to the prefabricated pile bottom plate is welded through the grouting pipe and subsequently threaded into the grouting conduit inserted into the pile body for grouting. The other end can be welded to the pile tip for pile sinking. Grouting holes are provided around the grouting device for post-grouting at the pile bottom. Ear guards are set near the grouting holes to prevent the side wall earthwork from compacting and affecting the grouting pressure at the pile bottom during the pile driving process. Two pile side grouting pipes are welded on the side of the grouting device close to the prefabricated pile to facilitate pile side post-grouting. A stiffening steel plate is welded to the outside of the grouting device to increase its strength and rigidity, ensuring its bearing capacity during the pile driving process. The inside of the grouting device is also filled with stone to increase its compressive strength. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a material-saving and environmentally friendly prestressed pipe pile post-grouting device.

[0008] To achieve the above object, the present invention provides a prestressed pipe pile post-grouting device, comprising: a grouting steel pipe, a grouting steel pipe sealing plate, a rib plate, a pile sealing plate, a grouting device, a grouting pipe, and coarse sand; One end of the slurry discharge steel pipe is connected to one side of the pile sealing plate, and the other end of the slurry discharge steel pipe is closed by the slurry discharge steel pipe sealing plate. The wall of the slurry discharge steel pipe includes a slurry discharge hole. A through hole is provided on the other side of the pile sealing plate opposite to the slurry discharge steel pipe. The grouting device is inserted into the slurry discharge steel pipe through the through hole. The coarse sand is poured into the inside of the slurry discharge steel pipe. The grouting pipe is connected to the grouting device; the rib plate is vertically connected to the surface of the pile sealing plate and the periphery of the slurry discharge steel pipe, and there is at least one rib plate.

[0009] Furthermore, the rib is cross-shaped.

[0010] Furthermore, there are multiple slurry outlet holes.

[0011] Furthermore, the grouting device includes a check valve.

[0012] Furthermore, one end of the grouting pipe connected to the grouting device includes a connecting thread.

[0013] Furthermore, the corners of the ribs are chamfered.

[0014] The present invention also discloses a construction method using the aforementioned prestressed pipe pile post-grouting device, comprising: Welding the prestressed pipe pile post-grouting device to the pile body; Connect the grouting pipe to the grouting device; The grouting and expansion prestressed pipe pile and the grouting pipe are sunk into the soil by using a direct pile sinking process until the piles are sunk to the designed elevation; Inject cement slurry, and the cement slurry is injected into the pile bottom through the grouting pipe and the prestressed pipe pile post-grouting device to form an extrusion expansion section at the pile bottom.

[0015] Furthermore, the cement slurry uses P42.5 cement with a water-cement ratio of between 0.55 and 0.60.

[0016] Furthermore, the direct pile driving process is a static pressure process or a hammering process.

[0017] The technical effect of the present invention is that: there is no need for cement-soil mixing pile construction, and post-grouting of the pile bottom can be carried out at any time, without occupying an absolute construction period, and the construction is more efficient. In particular, compared with existing post-grouting devices, it reduces material usage, is simple to process, and has low installation costs.

[0018] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 is a cross-sectional view of a post-grouting device according to an embodiment of the present invention; Figure 2 A top view of a post-grouting device according to an embodiment of the present invention; Figure 3 This is a cross-sectional view of a construction state of an embodiment of the present invention.

[0020] Explanation of the accompanying reference numerals: 100 - post-grouting device; 200 - pile body; 1 - pile sealing plate; 2 - rib plate; 3 - slurry discharge steel pipe; 4 - slurry discharge steel pipe sealing plate; 5 - grouting device; 6 - grouting pipe; 7 - coarse sand; 10 - opening; 20 - welding surface. DETAILED DESCRIPTION

[0021] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0022] In the drawings, components with identical structures are denoted by the same reference numerals, and components with similar structures or functions are denoted by similar reference numerals. The size and thickness of each component shown in the drawings are arbitrary and are not limited by the present invention. For clarity, the thickness of components in some places in the drawings is appropriately exaggerated.

[0023] like Figure 1 and Figure 2 As shown, the present invention discloses a post-grouting device for prestressed pipe piles, comprising: a slurry outlet steel pipe 3, a slurry outlet steel pipe sealing plate 4, a rib plate 2, a pile sealing plate 1, a grouting device 5, a grouting pipe 6, and coarse sand 7.

[0024] The slurry discharge pipe 3 is a hollow steel pipe, one end of which is connected to one side of the pile closure plate 1, and the other end of which is sealed by the slurry discharge pipe closure plate 4. The pipe wall of the slurry discharge pipe 3 includes multiple slurry discharge holes 30. The other side of the pile closure plate 1 opposite the slurry discharge pipe 3 has a through hole 10, through which a grouting device 5 is inserted into the slurry discharge pipe 3. Coarse sand 7 is poured into the slurry discharge pipe 3, and the grouting pipe 6 is connected to the grouting device 7. The rib plate 2 is vertically connected to the pile closure plate 1, and there is at least one rib plate 2. Preferably, the particle size of the coarse sand 7 should be larger than the diameter of the slurry discharge hole 30 to prevent the coarse sand from leaking out of the slurry discharge hole 30.

[0025] There can be multiple grouting holes 30 distributed around the wall of the grouting steel pipe 30. During grouting by the grouting device 5, cement slurry overflows from the grouting holes 30 into the soil, penetrating and compacting the soil around the pile. Consequently, the soil around the pile body is compressed and expanded by the high-pressure cement slurry, gradually strengthening the pile and changing the consolidation state of the soil around the pile. This increases the pullout resistance and bearing capacity of the pipe pile. In a preferred embodiment, there are multiple grouting holes 30, each with a diameter of 8 to 10 mm.

[0026] Since the grouting steel pipe 3 is a hollow steel pipe and is in direct contact with the soil and bears the greatest stress, it requires reinforcement during pile sinking. In this embodiment, coarse sand 7 is used to fill the grouting steel pipe 3 to strengthen its rigidity and ensure that it is not damaged during pile sinking. During grouting, cement slurry can flow through the gaps between the coarse sand 7 particles without affecting the grouting pressure. Furthermore, the coarse sand 7 is also used to block the grouting hole 30 during pile sinking, preventing the soil from being pressed into the grouting steel pipe 3 as the pile sinking process progresses. Therefore, the coarse sand 7 should be dense in the grouting steel pipe 3.

[0027] Furthermore, the ribs 2 are multiple and cross-shaped to further break up the soil and increase the pressure of the pipe pile during the pile sinking process.

[0028] Furthermore, the diameter of the slurry discharge steel pipe sealing plate 4 is larger than the diameter of the slurry discharge steel pipe 3. This facilitates the connection between the slurry discharge steel pipe sealing plate 4 and the slurry discharge steel pipe 3, preferably by welding.

[0029] Furthermore, the grouting device 5 includes a check valve to prevent the cement slurry injected through the grouting pipe 7 from flowing back.

[0030] Furthermore, in order to fix the grouting pipe 7 and the grouting device 5 and prevent the grouting pipe 7 from deviating from the grouting device 5 during the pile sinking process, threads can be machined on the end of the grouting pipe 7 and the grouting pipe 7 and the grouting device 5 are threadedly connected.

[0031] Furthermore, the corners of the ribs 2 are chamfered to reduce the resistance of the pile body to the soil during pile sinking.

[0032] Furthermore, the pile body 200 and the post-grouting device 100 are separate, so the pile body 200 and the post-grouting device 100 can be manufactured separately in a factory and transported to a construction site, and then directly welded together at the construction site. Figure 3 The pile body 200 and the welding surface 20 with the post-grouting device 100 are shown.

[0033] The present invention also discloses a construction method using the aforementioned prestressed pipe pile post-grouting device, comprising: Step S201: welding the post-grouting device 100 to the pile body 200; Step S202: Connect the grouting pipe 6 to the grouting device 5; Step S203: using a direct pile sinking process to sink the grouting and expansion prestressed pipe pile and the grouting pipe into the soil until the pile is sunk to the designed elevation; Step S204: injecting cement slurry, wherein the cement slurry flows along the grouting pipe toward the bottom of the rear grouting device of the prestressed pipe pile, forming an extrusion expansion section at the pile bottom.

[0034] Cement slurry can be injected into the grouting pipe 6 using a high-pressure grouting pump. The above construction method reduces the concrete pouring or slurry replacement steps in conventional pile driving. The construction method is simple, and the cement slurry is directly injected through the grouting pipe 6 and overflows from the slurry outlet 30, which reduces the amount of cement slurry used and controls the flow path of the cement slurry, reducing the material consumption of the cement slurry, reducing costs, and having very little impact on the environment. At the same time, the pull-out resistance and stability of the prestressed pipe piles are not affected, and they still have a large foundation bearing capacity. The direct pile driving process adopted in the construction method includes static pressure or hammering process, and the construction equipment is simple and has a wide adaptability.

[0035] Furthermore, the cement slurry uses P42.5 cement with a water-cement ratio of between 0.55 and 0.60. P42.5 refers to the strength grade of ordinary Portland cement, i.e., the 28-day compressive strength standard of ordinary Portland cement is not less than 42.5 MPa.

[0036] When preparing cement slurry, attention should be paid to stirring to ensure that the slurry does not segregate. The mixing system used should have two slurry barrels (mixing barrel and slurry barrel). The cement mortar liquid must be stirred in the mixing barrel, filtered through a filter screen, and then enter a special slurry barrel. At the same time, the slurry in the slurry barrel should also be equipped with a stirring system. The slurry in the slurry barrel should not be placed for more than 3 hours. The grouting pressure and grouting rate should be strictly controlled during grouting. The termination control standard of grouting adopts the dual control standard of grouting volume and grouting pressure. The grouting flow rate should not exceed 50L / min and should not be lower than the design requirements. The grouting pressure is controlled at 1.0~1.8Mpa.

[0037] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A prestressed pipe pile post-grouting device, characterized in that: The post-grouting device for prestressed pipe piles includes a slurry outlet steel pipe, the pipe wall of the slurry outlet steel pipe includes a slurry outlet hole, and the interior of the slurry outlet steel pipe is filled with coarse sand to enhance the rigidity of the slurry outlet steel pipe. The particle size of the coarse sand is larger than the diameter of the slurry outlet hole. The coarse sand is dense in the slurry outlet steel pipe, so that the coarse sand is used to block the slurry outlet hole on the pipe wall of the slurry outlet steel pipe when sinking the pile.

2. The prestressed pipe pile post-grouting device according to claim 1, characterized in that: The prestressed pipe pile post-grouting device further comprises a rib plate and a pile sealing plate, wherein the rib plate is vertically connected to the surface of the pile sealing plate and the periphery of the slurry outlet steel pipe in a cross shape.

3. The post-grouting device for prestressed pipe piles according to claim 2, characterized in that: The rib is cross-shaped.

4. The prestressed pipe pile post-grouting device according to claim 2 or 3, characterized in that: There is at least one rib.

5. The prestressed pipe pile post-grouting device according to any one of claims 1 to 4, characterized in that: There are multiple slurry outlet holes on the pipe wall of the slurry outlet steel pipe.

6. The post-grouting device for prestressed pipe piles according to any one of claims 1 to 5, characterized in that: The prestressed pipe pile post-grouting device further comprises a grouting device, and the grouting device comprises a check valve.

7. The prestressed pipe pile post-grouting device according to claim 6, characterized in that: The prestressed pipe pile post-grouting device further comprises a grouting pipe, which is connected to the grouting device, and one end of the grouting pipe connected to the grouting device comprises a connecting thread.

8. The prestressed pipe pile post-grouting device according to any one of claims 2 to 7, characterized in that: The corners of the ribs are chamfered.

9. The prestressed pipe pile post-grouting device according to any one of claims 1 to 8, characterized in that: The diameter of each slurry outlet hole on the pipe wall of the slurry outlet steel pipe is 8 to 10 mm.

10. A construction method using the prestressed pipe pile post-grouting device according to any one of claims 1 to 9, characterized in that: The method comprises: Welding the prestressed pipe pile post-grouting device to the pile body; Connect the grouting pipe to the grouting device; The grouting and expansion prestressed pipe pile and the grouting pipe are sunk into the soil by using a direct pile sinking process until the piles are sunk to the designed elevation; Cement slurry is injected, and the cement slurry flows along the grouting pipe to the bottom of the prestressed pipe pile rear grouting device, forming an extrusion expansion section at the pile bottom.

11. The construction method using the prestressed pipe pile post-grouting device according to claim 10, characterized in that: The cement slurry uses P42.5 cement with a water-cement ratio of 0.55 to 0.

60.

12. The construction method using the prestressed pipe pile post-grouting device according to claim 10 or 11, characterized in that: The direct pile driving process is a static pressure process or a hammering process.

13. The construction method using the prestressed pipe pile post-grouting device according to any one of claims 10 to 12, characterized in that: The cement slurry is injected into the grouting pipe using a high-pressure grouting pump.

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