CN102605767A - Precast pile reserved with grouting pipe and piling process of precast pile - Google Patents

Abstract

A prefabricated pile with a reserved grouting pipe, comprising a pile body, the bottom of the pile body is fixedly connected with the pile head, and a pile side grouting pipe and a pile end grouting pipe are arranged inside the pile body; the pile end grouting pipe is located at The center position of the pile body, the pile side grouting pipe interval preset pile side one-way grouting outlet, the lower end of the pile end grouting pipe is connected with the outlet at the lower end of the pile body; the upper end of the pile side grouting pipe The pile side connecting pipe is installed, the pile end connecting pipe is installed on the upper end of the pile end grouting pipe, and the pile side connecting pipe and the pile end connecting pipe are all connected with the upper surface of the pile body. And a pile-forming process. The invention provides a prefabricated pile with a reserved grouting pipe and a pile forming process which can effectively improve pile side friction force and pile end bearing capacity and reduce cost.

Description

A prefabricated pile with reserved grouting pipe and its pile forming process

technical field

The invention relates to a prefabricated pile and a pile forming process thereof.

Background technique

With the vigorous development of my country's construction industry, pile foundation has become a deep foundation form widely used in various buildings, especially high-rise buildings, heavy factory buildings, and subway stations. According to different classification standards, pile foundations can be divided into different types. According to the method of pile formation, they can be divided into: prefabricated piles (wooden piles, steel piles, concrete piles), cast-in-place piles (sinking tube cast-in-place piles, bored cast-in-place piles, hollowed-out piles) Cast-in-situ piles), in-situ mixing piles, etc. From the perspectives of economy, environmental protection, and safety, the use of concrete prefabricated piles and cast-in-situ piles is quite common. It has obvious advantages in the construction of prefabricated piles in the soft soil layer of the covering layer, the soil layer with a lot of groundwater, and the emergency construction period. If it becomes a weak surface, the cracks in the pile body will reduce the strength of the pile body after sinking the pile, the bearing capacity of the pile tip is not high, and the frictional resistance of the pile side is small. For bored cast-in-situ piles, although they are suitable for complex soil layers, the quality of the pile body is not easy to control, and problems such as broken piles, exposed tendons, and mud inclusions are prone to occur, resulting in low bearing capacity of single piles. In recent years, the post-grouting process has been developed and widely used, but it is not easy to ensure the smoothness of the grouting hole when the post-grouting process is used in bored piles; for PHC pipe piles, because the pipe wall is too thin, the horizontal bearing The post-grouting process introduced from this can improve the horizontal bearing capacity of the pipe pile, but it is difficult to control the pile side grouting when grouting at the pile bottom at the same time, and the pile bottom grouting needs to control the drilling issues of depth. According to the above problems, if a new technology combining prefabricated piles and post-grouting can be developed, many problems will be solved for the construction of pile foundations. Prefabricated piles with reserved grouting pipes are the implementation of this idea.

Contents of the invention

In order to overcome the deficiencies of the existing prefabricated piles and their pile forming process, which have relatively small pile side friction, small pile end bearing capacity, and high cost, the present invention provides a method that effectively improves pile side friction and pile end bearing capacity, reduces Cost reserved grouting pipe prefabricated pile and its pile forming process.

The technical solution adopted by the present invention to solve its technical problems is:

A prefabricated pile with a reserved grouting pipe, comprising a pile body, the bottom of the pile body is fixedly connected with the pile head, and a pile side grouting pipe and a pile end grouting pipe are arranged inside the pile body; the pile end grouting pipe is located at The center position of the pile body, the pile side grouting pipe interval preset pile side one-way grouting outlet, the lower end of the pile end grouting pipe is connected with the outlet at the lower end of the pile body; the upper end of the pile side grouting pipe The pile side connecting pipe is installed, the pile end connecting pipe is installed on the upper end of the pile end grouting pipe, and the pile side connecting pipe and the pile end connecting pipe are all connected with the upper surface of the pile body.

Further, the pile head includes a conical head and a cylindrical body, and the cylindrical body is in the shape of a cage or a net.

Furthermore, a four-way pipe is installed at the lower end of the pile end grouting pipe.

Still further, gravel is filled in the pile head.

The pile body has at least two sections, the outlet at the lower end of the upper pile body is connected to the upper surface of the adjacent lower pile body, and the two side grouting pipes in the upper and lower adjacent pile bodies are connected, and the two pile ends The grouting pipe is connected.

The pile side grouting pipe and the pile end grouting pipe are corrugated pipes.

A pile-forming process for prefabricated piles with reserved grouting pipes, the pile-forming process comprises the following steps:

(1), arrange formwork and steel bars, set the pile end grouting pipe at the center of the pile body, and arrange the pile side grouting pipe at the pile side of the pile body,

(2) Process the pile body of the prestressed pile with the pretensioning method;

(3) Start grouting after piling and sending the pile to the design elevation;

(4) Connecting pipes are used to connect the grouting pipe joints with the pile side grouting pipe and the pile end grouting pipe respectively;

(5) Dredge the pile side grouting pipe and the pile end grouting pipe with high pressure water, and open the grout outlet;

(6) The pile side grouting is carried out first, and then the pile end grouting is carried out to form a prefabricated pile.

Further, in the step (1), the main bodies of the pile side grouting pipe and the pile end grouting pipe are made of plastic corrugated pipes, and the connecting pipes at the ends are steel pipes with internal threads.

Still further, in the step (1), the two ends of the pile body are provided with embedded parts; in the step (2), the embedded parts of the two sections of the pile body adjacent up and down are butt-welded.

In the step (1), the formwork is provided with a hole matching the one-way slurry outlet on the side of the pile.

The technical idea of the present invention is: on the one hand, the plastic corrugated pipe used has good bending performance; on the other hand, when the prestressing force is applied and the prestressed steel bar is cut off, it can coordinate the deformation of the pile body and tightly bite with the pile body. Secondly, the low price of the plastic corrugated pipe can save the engineering cost, and the design has great advantages in all aspects.

When the pile side grout is injected, the mud skin on the pile side is firstly destroyed and eliminated, which can infiltrate and compact the soil around the pile, and fill the gap between the pile and the soil around the pile side. With the increase of the number of soil retaining walls, the site wall mud skin is destroyed and squeezed out of the ground surface under the action of top pressure, filling, and extrusion of high-pressure grout, gradually expanding the range of pile side compaction area, and changing the stress path and consolidation state of pile side soil. When the pile side is soil with poor permeability such as cohesive soil or silty soil, split grouting will be formed. If the pile side is a soil layer with better permeability such as gravel, the pile side compaction grouting state will be formed. Post grouting on the pile side causes the process of compaction, infiltration, filling, splitting and other processes between the cement slurry and the pile side mud skin and soil layer, which improves the strength of the pile side soil and the adhesion between the pile side concrete and soil. In addition, the diameter of the pile is increased, and the frictional resistance of the pile side is increased, thereby increasing the bearing capacity of the single pile.

During pile tip grouting, due to the existence of gravel in the prefabricated pile head, on the one hand, it can prevent the grout outlet at the pile tip from being blocked to form a good grout channel. The combination of steel bars forms concrete with relatively high compressive capacity. Moreover, as the amount of grouting increases, the pile bottom gradually forms a "pear-shaped head" and the compaction area gradually expands. Finally, the bottom of the pile can produce the effect of an expanded bottom pile, and the bearing capacity of a single pile will also be greatly improved.

The invention is suitable for the situation where the traditional prefabricated piles are suitable for the overlying soil layer is soft soil layer, the groundwater flow is large, and the construction period is relatively tight. In addition, the invention combines the advantages of the post-grouting process of traditional prefabricated piles, prestressed pipe piles and bored piles, and has higher pressure bearing capacity and pullout resistance than traditional prefabricated piles.

The beneficial effects of the present invention are mainly manifested in: (1) The low prestress applied by the steel bars of the pile body can effectively reduce the cracks in the process of hanging and driving piles, and can ensure the quality of the pile body. (2) The layout of the grouting pipes is more reasonable, not easy to be blocked, and the construction efficiency is improved. (3) The defects of the pile connection can be compensated by the grouting process, and in the case of cracks in the pile body, post-pressing grouting can fill the cracks to achieve the effect of repairing the pile body. (4) The side friction force of the pile and the bearing capacity of the pile end are greatly improved, thereby reducing the number of pilings and saving the cost. (5) The post-grouting is considered in the design, which saves manpower and financial resources compared with post-grouting as a remedial measure, and also achieves the purpose of cost-effectiveness. (5) The process is simple, and the construction period can be greatly shortened under the premise of ensuring the bearing capacity of the pile body. (6) Slag and construction waste can be used as pile head filler, and waste products can be reused to save energy and protect the environment.

The present invention has the above-mentioned characteristics at the same time, thereby greatly improving the bearing capacity of the pile while reducing the engineering cost, and can effectively serve the pile foundation engineering.

Description of drawings

Fig. 1 is a schematic diagram of the prefabricated pile body structure with reserved grouting pipes.

Fig. 2 is a schematic diagram of the A-A section structure of the prefabricated pile with reserved grouting pipes.

Fig. 3 is a schematic diagram of the pile body A-A of the connecting section of the prefabricated pile with reserved grouting pipes.

Fig. 4 is a schematic diagram of the B-B cross-sectional structure of the prefabricated pile with reserved grouting pipes.

Figure 5 is a schematic diagram of the pile head structure.

Fig. 6 is a schematic diagram of the pile-connecting jig.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

Example 1

Referring to Figures 1 to 4, a prefabricated pile with reserved grouting pipes is combined with prefabricated piles and post-grouting technology. 7; The pile head 10 is prefabricated, the pile head is filled with gravel 9, and the pile head and the pile end are welded into a whole. The one-way grouting outlet 6 on the pile side is preset in the pile side grouting pipe section, and the four-way pipe 8 connected to the pile end grouting pipe is set at the pile end as the pile bottom grouting outlet, so as to ensure that the three grouting outlets are evenly distributed ( The projection on the horizontal plane is 120°)

The above-mentioned prefabricated pile head 10 is a whole similar to a "yurt", and the cylindrical part (below the connection area with the pile end) is in the shape of a cage or a net.

Above-mentioned crushed stone 9 also can be replaced by gravel, steel slag, building debris.

Example 2

Referring to Figures 1 to 6, a pile-forming process for prefabricated piles with reserved grouting pipes includes the following steps:

(1) Arrange templates, steel bars and pile side grouting pipes 5, pile end grouting pipes 7, lower pile end embedded parts 11 and upper pile end embedded parts 13. The pile bottom grouting pipe 7 is arranged at the center, and the pile end The side grouting pipe 5 is arranged on the side of the pile; the main body of the grouting pipe is a plastic corrugated pipe (4 pipes can be used for the pile side grouting pipe, and 6 pipes can be used for the pile end grouting pipe), and the end connecting pipe is a steel pipe with internal thread 4.

(2) Use the pretensioning method to process the pile body of the prestressed pile, and the applied prestress should not be too large (4-6MPa is enough), so as to avoid the concrete of the pile body being crushed during pile driving.

(3) When the concrete reaches the strength requirement, cut off the excess steel bars at both ends, and reserve a length slightly smaller than the length of the pile head 10 cylinders for the steel bars at the pile end.

(4) Connect the slurry outlet at the pile end—the four-way pipe 8 (also can be pre-embedded).

(5) Fill the crushed stone material 9 in the prefabricated pile head 10, and the crushed stone material should not be overfilled to prevent damage to the pile end slurry outlet.

(6) Weld the pile head 10 with the lower pile end embedded part 11 according to the figure to form a pile.

(7) It is best to use special pile caps when driving piles to prevent damage to the grouting port, and start grouting after sending the piles to the design elevation.

(8) Using the connecting pipe 3 to connect the external joint 1 of the pile side grouting pipe and the external joint 2 of the pile end grouting pipe to corresponding internal threaded steel pipes respectively to form a grouting channel.

(9) Use high-pressure water to dredge the side grouting pipe 5 and the pile end grouting pipe 7, and open the grouting outlet.

(10) Grouting adopts measures of dual control of grouting pressure and grouting volume, firstly carry out pile side grouting, and then pile end grouting (generally about 6 hours after the end of pile side grouting).

In the case of pile connection, add embedded parts at both ends of each section of pile, and butt weld the embedded parts of the two sections of piles (the gap can be filled with gravel).

In order to ensure the integrity of the one-way grouting outlet 6 on the pile side after the pile is completed, it may be considered that in step 1, a hole slightly larger than the grouting pipe 5 on the pile side is reserved in the corresponding position of the formwork.

As shown in Figures 2 and 3, formwork, steel bars and pile side grouting pipe 5, pile end grouting pipe 7, lower pile end embedded part 11 and upper pile end embedded part 13 are arranged in order to ensure that the pile end grouting pipe 7 is set as far as possible. At the center position, the pile side grouting pipe 5 is arranged on the pile side; the main body of the grouting pipe adopts a plastic corrugated pipe (a quarter pipe for the pile side grouting pipe, and a sextant pipe for the pile end grouting pipe), and replaces it with a belt at the end. There is a steel pipe 4 with internal thread; the prefabricated pile head 10 is filled with crushed stone material 9 to improve the grouting effect, and the crushed stone material should not be filled too much to prevent damage to the pile end grout outlet; Embedded parts 11 are welded into piles; grouting adopts the measures of double control of grouting pressure and grouting volume, firstly carry out pile side grouting, and then carry out pile end grouting (generally 6 hours after pile side grouting).

Claims (10)

1. A prefabricated pile with a reserved grouting pipe, comprising a pile body, the bottom of the pile body is fixedly connected with the pile head, and it is characterized in that: a pile side grouting pipe and a pile end grouting pipe are arranged in the pile body; The pile end grouting pipe is located at the center of the pile body, the pile side grouting pipe section is preset with a one-way grouting outlet on the pile side, and the lower end of the pile end grouting pipe communicates with the outlet at the lower end of the pile body; the pile A pile side connecting pipe is installed on the upper end of the side grouting pipe, and a pile end connecting pipe is installed on the upper end of the pile end grouting pipe, and both the pile side connecting pipe and the pile end connecting pipe are connected with the upper surface of the pile body. 2. The prefabricated pile with reserved grouting pipe according to claim 1, characterized in that: the pile head includes a conical head and a cylindrical body, and the cylindrical body is in the shape of a cage or a net. 3. The prefabricated pile with reserved grouting pipe according to claim 1 or 2, characterized in that: a four-way pipe is installed at the lower end of the grouting pipe at the pile end. 4. The prefabricated pile with reserved grouting pipe according to claim 1 or 2, characterized in that: the pile head is filled with gravel. 5. The reserved grouting pipe prefabricated pile according to claim 1 or 2, characterized in that: the pile body has at least two sections, the lower end outlet of the upper pile body and the upper end of the adjacent lower pile body The end faces are connected, and the two side grouting pipes in the upper and lower adjacent pile bodies are connected, and the two pile end grouting pipes are connected. 6. The prefabricated pile with reserved grouting pipe according to claim 1 or 2, characterized in that: the pile side grouting pipe and the pile end grouting pipe are corrugated pipes. 7. A pile-forming process of the reserved grouting pipe prefabricated pile as claimed in claim 1, characterized in that: the pile-forming process comprises the following steps: (1), arrange formwork and steel bars, set the pile end grouting pipe at the center of the pile body, and arrange the pile side grouting pipe at the pile side of the pile body, (2) Process the pile body of the prestressed pile with the pretensioning method; (3) Start grouting after piling and sending the pile to the design elevation; (4) Connecting pipes are used to connect the grouting pipe joints with the pile side grouting pipe and the pile end grouting pipe respectively; (5) Dredge the pile side grouting pipe and the pile end grouting pipe with high pressure water, and open the grout outlet; (6) The pile side grouting is carried out first, and then the pile end grouting is carried out to form a prefabricated pile. 8. The pile-forming process of prefabricated piles with reserved grouting pipes as claimed in claim 7, characterized in that: in the step (1), the main bodies of the pile side grouting pipes and the pile end grouting pipes are all made of plastic corrugated Pipe, the end connecting pipe is a steel pipe with internal thread. 9. The pile forming process of reserved grouting pipe prefabricated piles as claimed in claim 7 or 8, is characterized in that: in the described step (1), the two ends of the pile body are provided with embedded parts; the described step (2) ), butt-weld the pre-embedded parts of the upper and lower adjacent piles. 10. The pile-forming process of prefabricated piles with reserved grouting pipes as claimed in claim 7 or 8, characterized in that: in the step (1), the formwork is provided with a unidirectional grout outlet on the side of the pile. hole.

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