Construction method of expanded core composite pile

Abstract

This application relates to the field of expanded core composite pile construction technology, and in particular to a construction method for expanded core composite piles, including: S1: site preparation; S2: pile position marking; S3: external pile forming: drilling with grouting using high-pressure jet grouting; after reaching the pile bottom position, repeated stirring is performed, with stirring within 2m above the pile bottom elevation; after repeated stirring, the drill is lifted; S4: pipe pile prefabrication and pretreatment, during pipe pile forming, steel sleeves are pre-embedded at both ends as welding connection points for subsequent pipe pile driving; after pipe pile forming, anti-friction grease is applied to the outer wall of the pipe pile to reduce driving resistance; S5: pipe pile driving, using a pile-by-pile driving method, with the head of each pipe pile protruding at a certain height during driving, and welded to the bottom of the next pipe pile to form a whole. This invention effectively solves the problems of insufficient pile bottom strength, poor pile joint verticality, and high driving resistance in traditional piles, resulting in high pile bearing capacity, standardized construction, and stable pile quality.

Description

Technical Field

[0001] This application relates to the field of expanded core composite pile construction technology, and in particular to a construction method for expanded core composite piles. Background Technology

[0002] Expanded core composite piles are a type of pile formed by combining two or three of the following: loose piles (piles formed from loose materials such as crushed stone, sand, brick and tile fragments, steel slag, and mineral slag), flexible piles (such as cement mixing piles and high-pressure jet grouting piles), and rigid piles (such as precast reinforced concrete piles and cast-in-place piles).

[0003] Currently, construction often employs a composite pile system, where high-pressure jet grouting piles serve as the outer piles and precast pipe piles form the core. During construction, high-pressure jet grouting piles are first formed at the pile location, and then precast pipe piles are inserted inside to create the composite pile. High-pressure jet grouting piles offer advantages such as low cost, minimal pollution, minimal construction disturbance, and excellent reinforcement of the surrounding soil. The inserted precast pipe pile core boasts high bearing capacity, high pile strength, and strong resistance to horizontal loads, making it widely used in numerous engineering projects.

[0004] Currently, when forming the outer piles of high-pressure jet grouting piles, the drill is typically lifted directly after reaching the pile bottom. However, on the one hand, the pile bottom, as the entire supporting foundation, requires greater support strength. On the other hand, during the drilling process, a large amount of soil settles and accumulates at the pile bottom. Therefore, with the current construction method, the structural strength of the outer pile is relatively low at the time of formation, insufficient to support the actual support requirements. Therefore, further improvements are warranted. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this application provides a construction method for expanded core composite piles to solve the problems in the prior art.

[0006] The construction method for expanded core composite piles provided in this application adopts the following technical solution: A construction method for expanded core composite piles includes the following steps: S1: Site preparation: Before the equipment enters the site, obstacles in the construction area are cleared and the site is leveled; S2: Pile positions are measured and marked; S3: External pile forming: First, the drilling rig is moved to the pile position, and then the drilling is carried out by high-pressure jet grouting; after reaching the pile bottom position, multiple re-mixing is carried out, and the re-mixing is carried out within 2m above the pile bottom elevation; after the re-mixing is completed, the drill is lifted; S4: Pipe pile prefabrication and pipe pile pretreatment; S5: Pipe pile installation.

[0007] By adopting the above technical solution, high-pressure jet grouting is used to form cement-soil external piles. The 2m section above the pile bottom is repeatedly stirred to break up the soft soil accumulated at the pile bottom, improve the density of cement-soil at the pile tip, and increase the bearing capacity of the pile foundation. Subsequently, segmented precast pipe piles are inserted into the external pile to form core-expanded composite piles. The construction process is standardized and the pile quality is stable.

[0008] Optionally, in step S5, when the pipe piles are driven into the ground, they are driven one by one. At the same time, when each pipe pile is driven into the ground, it is necessary to weld it to the bottom of the next pipe pile when its head is exposed at a certain height to form a whole.

[0009] By adopting the above technical solution, the pipe piles are prefabricated in sections and welded on site section by section, avoiding the problem of hoisting ultra-long piles, resulting in good weld quality and excellent overall integrity of the composite piles.

[0010] Optionally, in step S4, when the pipe pile is formed, steel sleeves are pre-embedded at both ends to serve as welding connection points when the pipe pile is driven into the ground; after the pipe pile is formed, anti-friction grease is applied to the outer wall of the pipe pile to reduce the driving resistance.

[0011] By adopting the above technical solution, the steel sleeves at both ends enable the rapid coaxial positioning of the upper and lower pipe piles, improving the docking accuracy; the grease on the outer wall reduces the side friction resistance between the pipe pile and the cement soil, making hammering the pile more labor-saving and avoiding damage to the pile body.

[0012] Optionally, step S5 specifically includes: S51, setting up and fixing a pile lowering auxiliary device at the pile location, which has the functions of rolling and clamping the pipe pile; S52, lowering the first pipe pile: using a crane to move the pipe pile to the pile location, the pile lowering auxiliary device rolls and clamps the pipe pile, cooperating with the crane to vertically align the pipe pile's insertion end with the center of the pile location, and slowly lowering it into the concrete outer pile. After lowering it into place, the head of the pipe pile protrudes above the ground to a certain height, which is the welding working height, and is fixed and clamped by the pile lowering auxiliary device; S53, splicing the pile: using a crane to move the next pipe pile to the pile location, the pile lowering auxiliary device... The auxiliary device rolls and clamps the pipe pile, cooperating with the crane to vertically align the bottom of the pipe pile with the lower pipe pile. After the two pipe piles are joined, they are welded together. S54, Hammering: After welding, the auxiliary device releases its clamping and fixation, while maintaining the rolling clamping. The hammering machine hammers the pipe pile into the concrete outer pile until the pipe pile head returns to the welding working height. The auxiliary device then fixes and clamps it. S55, Repeat steps S53-S54 until the last pipe pile. Hammer it until the pipe pile head protrudes a certain height above the ground, then remove the auxiliary device and finally hammer it completely in. By adopting the above technical solutions, the lowering, docking, welding and hammering are completed step by step with the help of special tooling, the verticality of the pile body is constrained throughout the process, the problems of pile deviation and skewed piles are eliminated, and the standardized operation improves construction efficiency.

[0013] Optionally, the pile lowering auxiliary device includes a base frame with a pile lowering opening in its middle. After fixing, the pile lowering opening is aligned with the pile position below, allowing the pipe pile to be inserted and lowered along this opening. The base frame is equipped with a rolling clamping mechanism and a fixed clamping mechanism at both the upper and lower positions of the pile lowering opening. The rolling clamping mechanism can perform centering rolling clamping, and the fixed clamping mechanism can perform centering fixed clamping. The upper rolling clamping mechanism is located above the fixed clamping mechanism, and the lower rolling clamping mechanism is located below the fixed clamping mechanism. In step S52, when the first pipe pile is lowered, after the pipe pile enters the pile lowering opening of the base frame, the upper and lower sets of rolling clamping mechanisms perform centering rolling clamping on the pipe pile, keeping it vertical and aligned with the pile position. As the pipe pile is lowered, it gradually inserts into the concrete... In the external pile construction process, after the pipe pile is lowered into place, the top of the pipe pile falls between the upper and lower fixed clamping mechanisms, and is then clamped and fixed by the lower fixed clamping mechanism. In step S53, when splicing the pile, the crane inserts the next pipe pile into the lower pile opening of the foundation frame. The upper rolling clamping mechanism is used to center and roll the pipe pile, helping the pipe pile to move down while maintaining a vertical position aligned with the pile location, until the bottom of the upper pipe pile contacts the bottom of the lower pipe pile. The upper fixed clamping mechanism is then used to fix the upper pipe pile, and then welding is performed. In step S54, when hammering the pile, the upper and lower fixed clamping mechanisms are released. At this time, only the upper and lower rolling clamping mechanisms are used to maintain the rolling clamping of the pipe pile, assisting the hammering machine in hammering the pile into the concrete external pile.

[0014] By adopting the above technical solution, the upper and lower double-layer clamping is used in a partitioned manner, with rigid locking during the welding stage and rolling limit during the hammering stage, taking into account both welding stability and hammering guidance.

[0015] Optionally, the rolling clamping mechanism is a hollow roller chuck, which uses roller jaws to form a rolling clamping mechanism during use; the fixed clamping mechanism is a hollow chuck, which uses jaws to form a fixed clamping mechanism during use.

[0016] By adopting the above technical solutions, the hollow structure is adapted to the outer diameter of the pile body, the roller clamping does not scratch the pile body, and the rigid chuck locks securely.

[0017] Optionally, in step S3, when re-mixing is performed at the bottom of the pile, the number of re-mixing times is 4 to 8.

[0018] By adopting the above technical solutions, the construction period can be reasonably controlled while ensuring that the soil at the bottom of the pile is fully and evenly mixed, thus avoiding unnecessary repeated mixing and increasing construction costs.

[0019] Optionally, in steps S52 and S53, after the pipe pile is lowered into place, the welding working height of its head protruding above the ground is 0.8m to 1.2m.

[0020] By adopting the above technical solution, sufficient space is reserved for manual welding, ensuring the quality of weld seams and making the height dimensions economical and reasonable.

[0021] Optionally, in step S55, when the last pipe pile is driven, it is hammered until the head of the pipe pile protrudes from the ground at a height of 0.8m to 1.2m.

[0022] By adopting the above technical solution, the reserved height of the last pile section facilitates the final hammering after the tooling is removed, making the construction operation convenient.

[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. The high-pressure jet grouting pile bottom area within 2m is re-mixed a limited number of times to optimize the mixing effect of the soil at the pile bottom, greatly improve the bearing capacity of the pile tip, and effectively control the subsequent foundation settlement; 2. Steel sleeves are pre-embedded at both ends of the pipe pile and the outer wall is coated with a friction-reducing coating, which ensures high docking accuracy, low pile driving resistance, and reduces the probability of pile damage. 3. Equipped with a dedicated double-layer clamping pile lowering fixture, the fixed / rolling clamping can be switched in stages to ensure the verticality of the pile body throughout the process, significantly improving the pile completion qualification rate; 4. A uniform welding allowance height of 0.8 to 1.2m ensures excellent welding conditions. The segmented pile splicing process solves the problem of hoisting ultra-long pipe piles, resulting in high overall construction efficiency. Attached Figure Description

[0024] Figure 1 This is an overall construction flow diagram of the construction method for an expanded core composite pile according to this application.

[0025] Figure 2 This is a construction flowchart of step S5 in the construction method of the expanded core composite pile of this application. Detailed Implementation

[0026] The present application will be further described in detail below with reference to the accompanying drawings.

[0027] This application discloses a construction method for expanded core composite piles.

[0028] Reference Figure 1 , 2 A construction method for expanded core composite piles includes the following steps: S1: Site preparation: Before the equipment enters the site, remove obstacles in the construction area and level the site; S2: Measure and mark the pile positions; S3: External pile forming; S4: Pipe pile prefabrication and pipe pile pretreatment; S5: Pipe pile installation.

[0029] Step S3 includes: First, moving the drilling rig to the pile placement location, and then drilling down by mixing and spraying grout using a high-pressure rotary jet method; after reaching the pile bottom position, performing multiple re-mixing operations within a height of 2m above the pile bottom elevation; and finally, lifting the drill after completing the re-mixing.

[0030] In step S3, when re-stirring at the bottom of the pile, the number of re-stirring times is 4 to 8, and the specific number of re-stirring times can be selected according to the actual situation.

[0031] In step S4, when the pipe pile is formed, steel sleeves are pre-embedded at both ends to serve as welding connection points when the pipe pile is driven into the ground. After the pipe pile is formed, anti-friction grease is applied to the outer wall of the pipe pile to reduce the driving resistance.

[0032] In step S5, the pipe piles are driven one by one. At the same time, when each pipe pile is driven, it needs to be welded to the bottom of the next pipe pile when its head is exposed at a certain height to form a whole.

[0033] Specifically, step S5 includes the following steps: S51. At the pile location, a pile lowering auxiliary device is erected and fixed, which has the functions of rolling clamping and fixing clamping of pipe piles. S52. Lowering the first pipe pile: Use a crane to move the pipe pile to the pile position. The pile lowering auxiliary device rolls and clamps the pipe pile. It works in conjunction with the crane to vertically align the pipe pile's entry end with the center of the pile position and slowly lower it into the concrete outer pile. After lowering it into place, the head of the pipe pile protrudes above the ground to a certain height. This is the welding working height, and it is fixed and clamped by the pile lowering auxiliary device. S53. Pile splicing: The next pipe pile is moved to the pile position using a crane. The pile lowering auxiliary device rolls and clamps the pipe pile. It works in conjunction with the crane to vertically align the bottom of the pipe pile with the pipe pile below. After the two pipe piles are joined together, they are welded together. S54, Hammering: After welding is completed, the pile lowering auxiliary device loosens the clamping and fixation, while maintaining rolling clamping. The pile is hammered into the concrete outer pile by the hammering machine until the pile head returns to the welding working height, and then fixed and clamped by the pile lowering auxiliary device. S55. Repeat steps S53 to S54 until the last pipe pile is driven in. Hammer the pipe pile until the head of the pipe pile protrudes above the ground to a certain height. Then remove the pile driving auxiliary device and finally hammer it in completely.

[0034] Specifically, in this embodiment, the pile lowering auxiliary device includes a base frame with a pile lowering opening in its middle. After fixing, the pile lowering opening is aligned with the pile position below, allowing the pipe pile to be driven through it. The base frame is equipped with a rolling clamping mechanism and a fixed clamping mechanism at positions above and below the pile lowering opening. The rolling clamping mechanism can perform centering rolling clamping, and the fixed clamping mechanism can perform centering fixed clamping. The upper rolling clamping mechanism is located above the fixed clamping mechanism, and the lower rolling clamping mechanism is located below the fixed clamping mechanism.

[0035] Based on the specific structure of the aforementioned pile-laying auxiliary device, therefore: When the first pipe pile is lowered in step S52, after the pipe pile enters the lower pile opening of the foundation frame, the upper and lower sets of rolling clamping mechanisms center and roll clamp the pipe pile to keep it vertical and aligned with the pile position. As the pipe pile is lowered, it is gradually inserted into the concrete outer pile. After it is lowered into place, the top of the pipe pile falls between the upper and lower fixed clamping mechanisms and is then clamped and fixed by the lower fixed clamping mechanism. When splicing the pile in step S53, the crane inserts the next pipe pile into the lower pile opening of the foundation frame. The upper rolling clamping mechanism is used to center and roll the pipe pile, helping the pipe pile to move down while maintaining a vertical position and aligned with the pile position, until the bottom of the upper pipe pile contacts the bottom of the lower pipe pile. The upper fixed clamping mechanism is then used to fix the upper pipe pile, and then welding is performed. When hammering the pile in step S54, the upper and lower fixed clamping mechanisms are released. At this time, the upper and lower rolling clamping mechanisms are used to maintain the rolling clamping of the pipe pile, which assists the hammering machine in hammering the pile into the concrete outer pile.

[0036] In this application, during steps S53, S54, and S55, a steel column can be temporarily installed on top of the pipe pile to assist in hammering the pipe pile to the welding height or the height of the last exposed section. For example, the temporary installation can be achieved by forming a protruding column at the bottom of the steel column, which is then inserted into the top of the pipe pile for temporary fixation. In other embodiments, the steel column can be installed at the hammer head of the pile hammering machine to assist in hammering the pipe pile, which will not be elaborated here.

[0037] In this embodiment, the rolling clamping mechanism is a hollow roller chuck, which uses the roller jaws to form a rolling clamping mechanism during use; the fixed clamping mechanism is a hollow chuck, which uses the jaws to form a fixed clamping mechanism during use.

[0038] In this embodiment, in steps S52 and S53, after the pipe pile is lowered into place, the welding working height of its head protruding above the ground is 0.8m to 1.2m.

[0039] In step S55, when the last pipe pile is driven, it is hammered until the head of the pipe pile protrudes from the ground at a height of 0.8m to 1.2m.

[0040] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A construction method for expanded core composite piles, characterized in that: Includes the following steps: S1: Site preparation: Before the equipment enters the site, remove obstacles in the construction area and level the site. S2. Measure and mark the pile positions; S3. External pile forming: First, move the drilling rig to the pile placement position, and then use high-pressure jet grouting to mix and spray grout into the pile. After reaching the bottom of the pile, perform multiple re-mixing operations, including re-mixing within 2m above the pile bottom elevation. After re-stirring, the drill bit is lifted. S4. Pipe pile prefabrication and pipe pile pretreatment; S5, Pipe pile driving.

2. The construction method of the expanded core composite pile according to claim 1, characterized in that: In step S5, the pipe piles are driven one by one. At the same time, when each pipe pile is driven, it needs to be welded to the bottom of the next pipe pile when its head is exposed at a certain height to form a whole.

3. The construction method of the expanded core composite pile according to claim 2, characterized in that: In step S4, when the pipe pile is formed, steel sleeves are pre-embedded at both ends to serve as welding connection points when the pipe pile is driven into the ground. After the pipe pile is formed, anti-friction grease is applied to the outer wall of the pipe pile to reduce the driving resistance.

4. The construction method of the expanded core composite pile according to claim 2, characterized in that: Step S5 specifically includes: S51. At the pile location, a pile lowering auxiliary device is erected and fixed, which has the functions of rolling clamping and fixing clamping of pipe piles. S52. Lowering the first pipe pile: Use a crane to move the pipe pile to the pile position. The pile lowering auxiliary device rolls and clamps the pipe pile. It works in conjunction with the crane to vertically align the pipe pile's entry end with the center of the pile position and slowly lower it into the concrete outer pile. After lowering it into place, the head of the pipe pile protrudes above the ground to a certain height. This is the welding working height, and it is fixed and clamped by the pile lowering auxiliary device. S53. Pile splicing: The next pipe pile is moved to the pile position using a crane. The pile lowering auxiliary device rolls and clamps the pipe pile. It works in conjunction with the crane to vertically align the bottom of the pipe pile with the pipe pile below. After the two pipe piles are joined together, they are welded together. S54, Hammering: After welding is completed, the pile lowering auxiliary device loosens the clamping and fixation, while maintaining rolling clamping. The pile is hammered into the concrete outer pile by the hammering machine until the pile head returns to the welding working height, and then fixed and clamped by the pile lowering auxiliary device. S55. Repeat steps S53 to S54 until the last pipe pile is driven in. Hammer the pipe pile until the head of the pipe pile protrudes above the ground to a certain height. Then remove the pile driving auxiliary device and finally hammer it in completely.

5. The construction method of an expanded core composite pile according to claim 4, characterized in that: The pile lowering auxiliary device includes a base frame with a pile lowering opening in the middle. After fixing, the pile lowering opening is aligned with the pile position below, allowing the pipe pile to be driven through it. The base frame is equipped with a rolling clamping mechanism and a fixed clamping mechanism at positions above and below the pile lowering opening. The rolling clamping mechanism can perform centering rolling clamping, and the fixed clamping mechanism can perform centering fixed clamping. The upper rolling clamping mechanism is located above the fixed clamping mechanism, and the lower rolling clamping mechanism is located below the fixed clamping mechanism. When the first pipe pile is lowered in step S52, after the pipe pile enters the lower pile opening of the foundation frame, the upper and lower sets of rolling clamping mechanisms center and roll clamp the pipe pile to keep it vertical and aligned with the pile position. As the pipe pile is lowered, it is gradually inserted into the concrete outer pile. After it is lowered into place, the top of the pipe pile falls between the upper and lower fixed clamping mechanisms and is then clamped and fixed by the lower fixed clamping mechanism. When splicing the pile in step S53, the crane inserts the next pipe pile into the lower pile opening of the foundation frame. The upper rolling clamping mechanism is used to center and roll the pipe pile, helping the pipe pile to move down while maintaining a vertical position and aligned with the pile position, until the bottom of the upper pipe pile contacts the bottom of the lower pipe pile. The upper fixed clamping mechanism is then used to fix the upper pipe pile, and then welding is performed. When hammering the pile in step S54, the upper and lower fixed clamping mechanisms are released. At this time, the upper and lower rolling clamping mechanisms are used to maintain the rolling clamping of the pipe pile, which assists the hammering machine in hammering the pile into the concrete outer pile.

6. The construction method of an expanded core composite pile according to claim 5, characterized in that: The rolling clamping mechanism is a hollow roller chuck, which uses roller jaws to form a rolling clamping mechanism during use; the fixed clamping mechanism is a hollow chuck, which uses jaws to form a fixed clamping mechanism during use.

7. The construction method of an expanded core composite pile according to claim 1, characterized in that: In step S3, when re-stirring at the bottom of the pile, the number of re-stirring cycles is 4 to 8.

8. The construction method of an expanded core composite pile according to claim 4, characterized in that: In steps S52 and S53, after the pipe pile is lowered into place, the welding working height of its head protruding above the ground is 0.8m to 1.2m.

9. The construction method of an expanded core composite pile according to claim 4, characterized in that: In step S55, when the last pipe pile is driven, it is hammered until the head of the pipe pile protrudes from the ground at a height of 0.8m to 1.2m.

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