Construction method of post-grouting screw pile of post-planting device

Abstract

The invention relates to the field of screw piles, in particular to a construction method of a post-grouting screw pile of a post-planting device, which comprises the following steps: prefabricating a grouting pipe and a reinforcement cage, mounting a grouting valve at the bottom of the grouting pipe, and fixing the grouting pipe on the reinforcement cage; a pile body of the screw pile is poured, before initial setting of the pile body, a reinforcement cage and a grouting pipe are implanted into the pile body by the designed depth, after the strength of the pile body is stable, a grouting pump is connected to the top of the grouting pipe, post-grouting operation is carried out, a grouting valve is opened under the action of grouting pressure from inside to outside, and slurry is injected into a rock-soil body at the pile end through the grouting pump. According to the embodiment of the invention, the technology of post-implantation of the grouting pipe and post-grouting is adopted in screw pile construction, virtual soil and mud cake at the pile bottom are effectively solidified, the compactness and bearing capacity of the pile bottom are improved, settlement of the pile foundation is reduced, and the long-term reliability and durability of the pile foundation are improved; and the integrity and the construction quality of the pile body structure are ensured.

Description

Technical Field

[0001] The invention relates to the field of screw piles, and in particular to a construction method of screw piles with post-grouting of a post-planting device. Background Art

[0002] Screw pile is a type of pile foundation widely used in foundation engineering, especially suitable for foundation support in soft soil, clay and other unfavorable geological conditions. Screw pile is drilled into the soil layer by rotation, and its spiral pile body design allows the pile body to effectively compact the surrounding soil during construction, thereby enhancing the stability and bearing capacity of the pile foundation.

[0003] However, in the actual construction process, the bottom of the screw pile often encounters the problem of loose soil and mud skin. Loose soil refers to the loose and unevenly compacted soil at the bottom of the pile caused by the disturbance during the spiral drilling process; mud skin is a layer of mud covering formed on the surface of the bottom of the pile due to the action of groundwater or mud during the construction process. These loose soil and mud skin will lead to insufficient bearing capacity of the pile bottom contacting the soil, increase the risk of pile settlement, and may affect the overall stability of the pile foundation. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method of screw piles with post-grouting of a post-planting device to solve the problem of insufficient bearing capacity of the soil at the bottom of the screw piles due to loose and uneven compaction of the soil caused by disturbance during spiral drilling during the construction of the screw piles.

[0005] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0006] A construction method for screw piles with post-grouting by post-planting device, comprising the following steps: prefabricating a grouting pipe and a steel cage, installing a grouting valve at the bottom of the grouting pipe, and fixing the grouting pipe on the steel cage; pouring the pile body of the screw pile, and before the pile body initially sets, implanting the steel cage and the grouting pipe into the designed depth inside the pile body to ensure that the grouting valve is located at the bottom of the pile body; after the strength of the pile body is stabilized, connecting a grouting pump to the top of the grouting pipe, performing post-grouting operation, the grouting valve opens under the action of grouting pressure from the inside to the outside, and the grouting pump injects slurry into the rock and soil.

[0007] Furthermore, during the process of prefabricating the steel cage, the grouting pipe is used to replace part or all of the main bars of the steel cage.

[0008] Furthermore, in the process of prefabricating the grouting pipe, grouting holes are set on the side walls of the grouting pipe, and a rubber sleeve is crimped on the outside of the grouting pipe so that the rubber sleeve closes the grouting hole to form the grouting valve, ensuring that the strength of the rubber sleeve meets the following conditions: the rubber sleeve will not be damaged during the process of implanting the grouting pipe into the screw pile, and the rubber sleeve will be damaged during the process of the grouting pump injecting slurry into the grouting pipe.

[0009] Furthermore, a plug is used to seal the bottom of the grouting pipe, and the plug is in a conical shape with the tip facing downward.

[0010] Furthermore, after the rubber sleeve is crimped onto the outer side of the grouting pipe, a braided sleeve is sleeved onto the outer side of the rubber sleeve to ensure that the diameter of the bottom wall of the plug is greater than the diameter of the braided sleeve.

[0011] Furthermore, before the slurry inside the grouting pipe initially sets, the bottom of the grouting pipe is closed.

[0012] Furthermore, the step of sealing the bottom of the grouting pipe includes: injecting epoxy resin into the bottom of the grouting pipe, and forming a second sealing layer after the epoxy resin is cured.

[0013] Furthermore, the step of injecting the epoxy resin into the bottom of the grouting pipe includes: during the prefabrication of the grouting pipe, installing a puncture needle above the grouting valve; after the grouting operation is completed, removing the grouting pump, and placing a double-cavity capsule into the interior of the grouting pipe, wherein the main agent and curing agent of the epoxy resin are pre-placed in the two cavities of the double-cavity capsule, and then connecting the grouting pump and the pressure gauge to the top of the grouting pipe to continue the grouting operation; stopping the grouting operation when the reading of the pressure gauge reaches a preset threshold value, at which time the double-cavity capsule is punctured, and the main agent and curing agent of the epoxy resin are mixed and then undergo a curing reaction.

[0014] Furthermore, in the process of prefabricating the grouting pipe, an annular support frame is installed at the bottom of the grouting pipe and above the grouting valve, the annular support frame is located at the same height as the puncture needle, and the inner ring of the annular support frame is rolled up to form a flange, and when the double-chamber capsule is punctured, the double-chamber capsule naturally shrinks and is mounted on the outside of the flange to form a first sealing layer.

[0015] Compared with the prior art, this application has the following beneficial effects:

[0016] Provided is a construction method for screw piles with a post-planting device and post-grouting. In the screw pile construction, the post-implantation grouting pipe and post-grouting technology are adopted to effectively solidify the loose soil and mud skin at the pile bottom, improve the density and bearing capacity of the pile bottom, reduce the settlement of the pile foundation, and improve the long-term reliability and durability of the pile foundation. In addition, the non-destructive grouting operation in the post-grouting process ensures the integrity of the pile structure and the construction quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the implementation of the present invention or the technical solution in the prior art, the following briefly introduces the drawings required for the implementation or the prior art description. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0018] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0019] Figure 2 It is a structural schematic diagram of a grouting valve according to an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a process of placing a double-cavity capsule into the bottom of a grouting pipe according to an embodiment of the present invention;

[0021] Figure 4 Schematic diagram of a process of forming a first sealing layer and a second sealing layer after a double-chamber capsule according to an embodiment of the present invention is punctured;

[0022] The numbers in the figure represent the following:

[0023] 1-pile body; 2-grouting pipe; 21-grouting hole; 22-plug; 3-reinforcement cage; 4-grouting valve; 41-rubber sleeve; 42-braided sleeve; 6-sleeve; 61-annular support frame; 62-flange; 63-puncture needle; 7-double-cavity capsule; 71-cavity. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Post-grouting is an auxiliary construction method for bored piles. This technology aims to solidify the loose soil and mud skin by post-grouting at the pile bottom, and to reinforce the soil at the pile bottom and a certain range around the pile, so as to improve the bearing capacity of the foundation pile, enhance the quality stability of the pile, and reduce the settlement of the pile foundation. For pile types such as drilled and excavated bored piles, practice has shown that good results have been achieved.

[0026] Therefore, people want to transfer the post-grouting technology to screw piles, so that the loose soil and mud skin at the bottom of the screw piles can be solidified, thereby improving the bearing capacity and quality stability of the screw piles.

[0027] Combination Figure 1 , Figure 2 The following provides a construction method of a screw pile with post-grouting of a post-planting device, comprising the following steps:

[0028] Step 1, prefabricate the grouting pipe 2 and the steel cage 3, install a grouting valve 4 at the bottom of the grouting pipe 2, install a wire plug at the top of the grouting pipe 2, tie or weld the grouting pipe 2 to the steel cage 3, and also use the grouting pipe 2 to replace part or all of the main bars of the steel cage 3.

[0029] Step 2: Cast the pile body 1 of the screw pile underground. After the pile body 1 is cast and before the initial setting, place the steel cage 3 and the grouting pipe 2 together into the interior of the pile body 1. First, use its own weight to insert the steel cage 3 into the concrete. When the steel cage 3 can no longer fall, connect the vibrator to the top of the steel cage 3 and use the exciting force of the vibrator to sink the steel cage 3 to the designed depth. At this time, the grouting valve 4 is located at the bottom of the pile body 1.

[0030] Step 3: After the strength of the pile body 1 is stabilized (generally 2 days after the pile is cast), unscrew the screw plug installed on the top of the grouting pipe 2, connect the output end of the grouting pump to the top of the grouting pipe 2, and implement the post-grouting operation. The grouting valve 4 is opened under the high-strength grouting pressure from the inside to the outside, and the slurry is injected into the rock and soil at the pile end to achieve non-destructive grouting.

[0031] Among them, the grouting valve 4 is a device that opens under specific pressure conditions. Its design purpose is to ensure that it can be opened under the pressure from the inside to the outside when the slurry is injected into the grouting pipe 2, and it will not be opened by the pressure of the external concrete during the insertion of the screw pile. Specifically, when the slurry pressure in the grouting pipe 2 is greater than the external concrete pressure, the grouting valve 4 will be opened or destroyed, thereby allowing the slurry to flow out for grouting. It can be in the form of a traditional valve or in the form of a plug with similar functions. The core of the grouting valve 4 lies in its pressure response characteristics, which ensures that it only works during grouting operations and remains closed under other circumstances.

[0032] The grouting valve 4 in this embodiment is in the form of a plug that is destroyed under high-intensity grouting pressure. A grouting hole 21 is formed on the side wall of the grouting pipe 2. The grouting valve 4 includes a rubber sleeve 41 wrapped around the outside of the grouting pipe 2 and closing the grouting hole 21. The rubber sleeve 41 is double-layered, and a braided sleeve 42 is mounted on the outside of the rubber sleeve 41. The braided sleeve 42 applies radial inward pressure to the rubber sleeve 41, so that the rubber sleeve 41 is firmly fixed to the outside of the grouting pipe 2.

[0033] During the process of inserting the grouting pipe 2 into the screw pile, the braided sleeve 42 provides protection for the rubber sleeve 41 to prevent the rubber sleeve 41 from being damaged due to friction with concrete.

[0034] When the grouting pump performs the grouting operation, the rubber sleeve 41 and the braided sleeve 42 rupture under the high-intensity grouting pressure, and the slurry flows out evenly toward the surroundings of the grouting pipe 2 through the grouting hole 21 .

[0035] The rubber sleeve 41 may be made of natural rubber, chloroprene rubber, EPDM rubber, etc., and the braided sleeve 42 may be made of glass fiber, aramid fiber, polyester fiber, nylon fiber, etc.

[0036] Furthermore, a plug 22 is installed at the bottom of the grouting pipe 2. The plug 22 is in the shape of a cone with the tip facing downward. The diameter of the bottom wall of the plug 22 is larger than the diameter of the braided sleeve 42. During the process of inserting the grouting pipe 2 into the screw pile, the plug 22 provides protection for the braided sleeve 42 to prevent the braided sleeve 42 from shifting due to friction with the concrete.

[0037] The material of the plug 22 may be steel, and the plug 22 is welded to the grouting pipe 2 .

[0038] The grouting pipe 2 is preferably a galvanized steel pipe with a diameter of 32 mm. When the length of the grouting pipe 2 is insufficient, two grouting pipes 2 can be connected by welding. Before welding, a sleeve 6 needs to be installed at the connection between the two galvanized steel pipes, and then the two ends of the sleeve 6 are welded to the two galvanized steel pipes respectively.

[0039] Furthermore, in order to prevent the slurry from flowing back into the grouting pipe 2 after the grouting is completed, the bottom of the grouting pipe 2 should be sealed before the grouting pump is removed. Since the rubber sleeve 41 and the braided sleeve 42 have been ruptured in the high-intensity grouting pressure, they cannot play a role in sealing the bottom of the grouting pipe 2. Moreover, due to the poor fluidity of the concrete slurry, even if the rubber sleeve 41 and the braided sleeve 42 of this embodiment are replaced with other types of one-way valves, it is difficult to achieve the purpose of closing the one-way valve to seal the grouting pipe 2.

[0040] To solve this problem, combined with Figure 3 and Figure 4 In this embodiment, epoxy resin is used to be inserted into the bottom of the grouting pipe 2 to perform the sealing operation.

[0041] An annular support frame 61 is pre-installed at the bottom of the grouting pipe 2. The annular support frame 61 is located above the grouting valve 4. The inner ring of the annular support frame 61 is rolled up to form a flange 62. A puncture needle 63 is fixed just below the center of the annular support frame 61. The annular support frame 61 and the puncture needle 63 are both fixed to a sleeve 6 connected to the grouting pipe 2 by welding. The annular support frame 61 and the puncture needle 63 are basically located at the same height.

[0042] The epoxy resin is contained in the double-cavity capsule 7, which is made of high-strength elastic material, such as polyurethane elastomer, nitrile rubber, silicone rubber, etc. Two independent cavities 71 are arranged inside the double-cavity capsule 7. The two cavities 71 are respectively filled with the main agent and curing agent of the epoxy resin. When the cavity 71 is filled, the double-cavity capsule 7 expands outward and remains taut.

[0043] When performing the operation of closing the bottom of the grouting pipe 2, the construction personnel throw the double-chamber capsule 7 from the top of the grouting pipe 2, then install a pressure gauge between the grouting pipe 2 and the grouting pump, and then continue the grouting operation.

[0044] When the double-chamber capsule 7 descends to the position of the annular support frame 61, the double-chamber capsule 7 is blocked by the annular support frame 61. At this time, the central part of the double-chamber capsule 7 sags under the dual effects of gravity and grouting pressure, and is finally punctured by the puncture needle 63 under the support frame.

[0045] After being punctured, the double-chamber capsule 7 loses the support of the internal liquid and will naturally shrink and tightly clamp the edge of the flange 62 of the annular support frame 61 to form a first sealing layer. The construction personnel judge the progress of the sealing operation by observing the grouting pressure displayed on the pressure gauge. When the grouting pressure displayed on the pressure gauge exceeds the predetermined threshold value, it means that the first sealing layer has been formed and the construction personnel stop grouting.

[0046] At this time, at the bottom of the grouting pipe 2, the main agent and the curing agent filled in the double-cavity capsule 7 flow out and mix, the mixed epoxy resin begins to cure, and forms a second sealing layer below the first sealing layer in a short time.

[0047] This double sealing structure ensures that the bottom of the grouting pipe 2 can be permanently sealed, effectively preventing the slurry from flowing back into the grouting pipe 2. There is no need to wait for the slurry inside the grouting pipe 2 to completely solidify. After the epoxy resin reaches the curing time, the grouting pump and pressure gauge can be removed.

[0048] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A method for constructing a screw pile with post-grouting of a post-planting device, characterized in that: The steps include: Prefabricate a grouting pipe and a steel cage, install a grouting valve at the bottom of the grouting pipe, and fix the grouting pipe on the steel cage; The pile body of the cast-in-place screw pile is, before the pile body is initially set, implanting the steel cage and the grouting pipe into the designed depth inside the pile body, ensuring that the grouting valve is located at the bottom of the pile body; After the strength of the pile body is stabilized, a grouting pump is connected to the top of the grouting pipe to implement post-grouting operations. The grouting valve is opened under the grouting pressure from the inside to the outside, and the grouting pump injects slurry into the rock and soil.

2. The method for constructing a screw pile with post-grouting of a post-planting device according to claim 1, characterized in that: During the prefabrication of the steel cage, the grouting pipe is used to replace part or all of the main bars of the steel cage.

3. The method for constructing a screw pile with post-grouting of a post-planting device according to claim 1, characterized in that: During the process of prefabricating the grouting pipe, grouting holes are set on the side wall of the grouting pipe, and a rubber sleeve is crimped on the outside of the grouting pipe so that the rubber sleeve closes the grouting hole to form the grouting valve, ensuring that the strength of the rubber sleeve meets the following conditions: the rubber sleeve will not be damaged during the process of implanting the grouting pipe into the screw pile, and the rubber sleeve will be damaged during the process of the grouting pump injecting slurry into the grouting pipe.

4. The method for constructing a screw pile with post-grouting of a post-planting device according to claim 3, characterized in that: The bottom of the grouting pipe is closed with a plug, which is in the shape of a cone with the tip facing downward.

5. The method for constructing a screw pile with post-grouting of a post-planting device according to claim 4, characterized in that: After the rubber sleeve is crimped onto the outer side of the grouting pipe, a braided sleeve is sleeved onto the outer side of the rubber sleeve to ensure that the diameter of the bottom wall of the plug is greater than the diameter of the braided sleeve.

6. A method for constructing a screw pile with post-grouting of a post-planting device according to any one of claims 1 to 5, characterized in that: Before the slurry inside the grouting pipe begins to set, the bottom of the grouting pipe is closed.

7. The method for constructing a screw pile with post-grouting of a post-planting device according to claim 6, characterized in that: The step of closing the bottom of the grouting pipe comprises: Epoxy resin is injected into the bottom of the grouting pipe, and the epoxy resin forms a second sealing layer after being cured.

8. The method for constructing a screw pile with post-grouting of a post-planting device according to claim 7, characterized in that: The step of injecting the epoxy resin into the bottom of the grouting pipe comprises: During the prefabrication of the grouting pipe, a puncture needle is installed above the grouting valve; After the grouting operation is completed, the grouting pump is removed, and a double-cavity capsule is placed inside the grouting pipe. The main agent and curing agent of the epoxy resin are pre-placed in the two cavities of the double-cavity capsule. Then, the grouting pump and the pressure gauge are connected to the top of the grouting pipe, and the grouting operation is continued. The grouting operation is stopped when the reading of the pressure gauge reaches a preset threshold value. At this time, the double-cavity capsule is punctured, and the main agent and curing agent of the epoxy resin are mixed and then cured.

9. The method for constructing a screw pile with post-grouting of a post-planting device according to claim 8, characterized in that: During the prefabrication of the grouting pipe, an annular support frame is installed at the bottom of the grouting pipe and above the grouting valve. The annular support frame is located at the same height as the puncture needle. The inner ring of the annular support frame is rolled up to form a flange. When the double-chamber capsule is punctured, the double-chamber capsule naturally shrinks and is mounted on the outside of the flange to form a first sealing layer.

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