CN108330958A - A kind of constructing device filled for composite pile foundation stake top cavity envelope - Google Patents

Abstract

The invention discloses a construction device for sealing the cavity of the pile top of a composite pile foundation: when performing secondary pouring on the pile top, the new type of grouting bottom pipe and the main reinforcement are welded firmly and poured inside the secondary pile top, and the pipe The hole is inserted into the pile top cavity; the new grouting bottom pipe outside the foundation pile is embedded in the shallow layer of the foundation soil, and is led out to the ground from the side of the raft. Compared with the traditional grouting method, the present invention can economically and reasonably realize the grouting and sealing of the cavity on the top of the pile, while ensuring the grouting effect, it can ensure that the integrity of the raft is not damaged and the binding of steel bars is guaranteed. Smooth development, reduce engineering costs and improve work efficiency.

Description

A construction device for sealing and filling the top cavity of composite pile foundation

technical field

The invention relates to a construction device for sealing and filling the pile top cavity of a composite pile foundation, in particular to a construction device for sealing and filling the pile top cavity of a composite pile foundation with elastic bearings arranged on the pile top.

Background technique

With the vigorous promotion of infrastructure construction in our country, pile foundation, an ancient foundation form, has been widely used and developed unprecedentedly. As one of the main manifestations of pile foundations, piled raft foundations have also developed rapidly in recent years. Pile raft foundations, as the name implies, refer to the foundation form in which piles and caps bear the load of the upper structure together. It has good foundation integrity and high bending rigidity. , wide adaptability and easy to realize pile-soil interaction and other advantages.

The direct rigid connection between piles and rafts in conventional pile-raft foundations, the overall stiffness is determined by the stiffness of the raft slab and the support stiffness of the pile foundation. If the stiffness of the pile raft needs to be adjusted for some reasons, the stiffness of the raft slab can be adjusted through the thickness of the raft, but the cost is often high; the support stiffness of the pile foundation can be adjusted by changing the pile length, pile diameter, and pile distance, but different The pile diameter and pile layout methods of different pile lengths are greatly affected by the superstructure form and geological conditions, and the application range is considerably limited. The new technology of composite pile foundation aims to adjust and optimize the support stiffness of the pile raft by setting elastic bearings between the pile top and the raft slab, which can economically and effectively adjust the overall stiffness of the pile raft foundation as needed.

Compared with the conventional pile-raft foundation, the only feature of the composite pile foundation is that an elastic support with artificial stiffness can be set on the top of the pile. The above improvements make it possible to effectively and economically intervene in the overall stiffness of the piled-raft foundation, and at the same time greatly expand the application field of the piled-raft foundation. According to the current research, the composite pile foundation can be used in the following situations: ① The shallow foundation soil has a high bearing capacity and has a certain utilization potential, and the pile foundation type is an end-bearing area, and the joint action of piles and soil needs to be considered Happening. This kind of situation is also called end-supported pile composite pile foundation, and it is called generalized composite pile foundation together with the conventional composite pile foundation applied in soft soil areas; Variable stiffness leveling design; ③Consider the bearing potential of the old pile foundation of the building, the situation that the new and old pile foundations share the load of the upper structure; Absence and soil-rock combination foundations and other situations where foundation soil support stiffness is seriously uneven; ⑤ Combination of two or more of the above situations.

In the form of composite pile foundation, in order to increase the durability of the pile top, the cavity of the pile top needs to be grouted and closed after the settlement of the building is stable. At present, the traditional grouting sealing method is mainly the "upward drawing method", that is, by opening a hole on the upper cover plate when the elastic support is installed, the grouting pipe and the cover plate are firmly welded and drawn out vertically through the raft, and the injection pulp.

At present, the traditional "introduction method" is the main grouting sealing method for composite pile foundations, and it has been applied in a certain range. However, there are many problems in the process of engineering practice, which are mainly divided into the following aspects:

1. The grouting pipe and the cover plate are welded and connected, and the cover plate must be drilled and welded. The cover plate is a steel plate of one to two centimeters, with high rigidity, and it is difficult to open holes on it, which greatly increases the production cost. ; The joints welded on the cover plate are inconvenient to protect during transportation, are easy to be damaged and deformed, and are not easy to replace, which brings great difficulties to the connection between the grouting pipe and the cover plate in the later stage.

2. The steel bars inside the raft are criss-crossed, and the number is huge. However, the "upward drawing method" is to lead the grouting pipe through the raft to the ground, which brings a huge problem: the steel bars are not easy to bind! Before the reinforcement is bound, the grouting pipe has been installed, and then the binding of the reinforcement will obviously "fight" with the grouting pipe. From previous engineering cases, it can be found that such as difficulties in lowering and transporting the reinforcement, and the grouting pipe being bumped or even hit by the reinforcement. Problems such as breakage and uneven arrangement of reinforcement caused by avoiding the position of the grouting pipe have repeatedly occurred.

3. The top of the grouting pipe protrudes about 20cm from the raft. Due to the action of groundwater, the groundwater in the pipe will continuously flow up before the grouting is closed, resulting in serious water accumulation in the basement. The decoration construction of the basement garage in the later period has brought a lot the inconvenience.

4. There are a large number of grouting pipes distributed in the raft. Although there is grout filling in the pipe in the later stage, the filling effect cannot be guaranteed, and the integrity of the raft is damaged. The service life of the building is generally more than 50 years. Whether there is a certain safety hazard under the load.

Contents of the invention

The object of the present invention is to provide a safe, reliable, technically feasible, economical and reasonable sealing and filling device for the pile top cavity of the composite pile foundation, aiming at the above-mentioned deficiencies in the prior art.

A construction device for sealing the cavity of the pile top of a composite pile foundation, comprising more than one grouting bottom pipe, and foundation piles, cover plates and rafts arranged in sequence from bottom to top; the foundation piles include The primary pouring pile body and the secondary pouring pile top, the primary pouring pile body and the secondary pouring pile top are connected and fixed through the main reinforcement; the cavity formed between the secondary pouring pile top and the cover plate is the pile top cavity, There is more than one pile top support built into the pile top cavity, the top of the pile top support is connected to the cover plate, and the bottom is connected to the secondary pouring pile top; The layer is wrapped with the concrete cushion, the concrete cushion and the foundation soil layer are stacked and arranged from top to bottom, and the gap between the side of the cover plate and the concrete cushion and the foundation soil layer is filled with sand; the grouting The bottom pipe includes a pipe body, a grout inlet and a grout outlet located at both ends of the pipe body; the grout inlet is connected to the outside, and after the pipe body passes through the pile top after the second pouring, the grout outlet is inserted into the pile top cavity, and the bottom pipe is grouted Weld firmly with the main reinforcement.

The present invention does not need to drill holes on the cover plate by setting the downward type grouting bottom pipe, which saves the cost and ensures the integrity of the cover plate; in addition, the position of the grouting bottom pipe changes without contact with the inside of the raft. The conflicts in the installation of the reinforced steel structure not only make it easier to advance the project, but also solve the problem of uneven arrangement; again, the bottom pipe of the grouting is no longer located on the raft, and the groundwater in the pipe will no longer be generated before the grouting is closed It will continue to flow up, causing serious water accumulation in the basement, which is convenient for subsequent construction; finally, the filling effect is relatively stable. The side of the cover plate is wrapped by the foundation soil layer and the concrete cushion, which is also to facilitate the installation of the grouting bottom pipe, reduce the construction difficulty and ensure the quality of the construction. During the construction of the solution of the present invention, the foundation form of the building adopts a composite pile foundation, and the pile top support is located inside the cavity, and the cavity needs to be sealed and filled after the later settlement is stable. Compared with the existing "upward citation method", the method of the invention improves the stability of the filling effect by 32%, and reduces the cost by about 50%.

As a preference, the top surface of the primary pouring pile body is located at 20cm-30cm below the concrete cushion, and the top surface of the secondary pouring pile is located at 5cm-10cm below the concrete cushion; The bottom part is 5cm-15cm, and the grout outlet of the grouting bottom pipe is inserted into the cavity by 5cm-10cm.

Preferably, the inner diameter of the grouting bottom pipe is 2.5cm, 3.2cm or 4.0cm.

Preferably, the body of the grouting bottom pipe also penetrates the foundation soil layer, and is led out from the side of the raft to the ground to communicate with the outside.

Beneficial effects: the invention discloses a construction device for sealing and grouting the cavity of the pile top of the composite pile foundation. The integrity of the board is not damaged and the steel bar binding work can be carried out smoothly, reducing engineering costs and improving work efficiency.

Description of drawings

Fig. 1 is a schematic structural diagram of a potting device of the traditional "up-priming method".

Fig. 2 is a schematic cross-sectional structure diagram of a sealing and filling device for a pile top cavity according to the present invention.

Fig. 3 is a schematic diagram of the planar structure of a sealing and filling device for a pile top cavity according to the present invention.

In the figure: 1. raft, 2. pile top cavity, 3. elastic support, 4. grouting bottom pipe, 5. concrete cushion, 6. foundation soil layer, 7. sand filling, 8. main reinforcement, 9 1. Second pouring pile top, 10. Foundation pile, 11. One-time pouring pile body, 12. Cover plate.

Detailed ways

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

As shown in Figure 1, in the existing potting device of the "upward lead method", the grouting bottom pipe 4 runs through the raft 1 and the cover 12 from top to bottom, and then extends into the cover 12 and the top of the secondary pouring pile. 9 in the pile top space 2, the problem is:

1. To penetrate the cover plate 12, the grouting bottom pipe 4 must be drilled and welded on the cover plate 12, and the cover plate 12 is a steel plate of one to two centimeters, with high rigidity, and it is difficult to open holes on it, which greatly Increased production costs; the joints welded on the cover plate 12 are not easy to protect during transportation, are easily damaged and deformed, and are not easy to replace, which brings great difficulties to the connection between the grouting bottom pipe 4 and the cover plate 12 difficulty.

2. The steel bars inside the raft 1 are criss-crossed, and the number is huge. However, the "upward drawing method" is to lead the grouting bottom pipe 4 through the raft 1 to the ground, which brings a great problem: the steel bars are not easy to bind! Before the steel bars are bound, the grouting bottom pipe 4 has been installed, and then the steel bars will obviously "fight" with the grouting bottom pipe 4. From previous engineering cases, it can be found that such as the difficulty of lowering and transporting the steel bars, the grouting bottom pipe 4 Problems such as being knocked crookedly or even broken by steel bars, and uneven layout of steel bars caused by avoiding the position of the grouting bottom pipe 4 have repeatedly occurred.

3. The top of the grouting bottom pipe 4 protrudes from the raft 1 by about 20cm. Due to the action of groundwater, the groundwater in the pipe will continuously flow upwards before the grouting is closed, resulting in serious water accumulation in the basement, which will cause serious problems for the decoration construction of the basement garage in the later period. It's a big inconvenience.

4. A large number of grouting bottom pipes 4 are distributed in the raft 1. Although the pipes are filled with grout in the later stage, the filling effect cannot be guaranteed, the integrity of the raft 1 is damaged, and the service life of the building is generally longer than 50 years, whether there are certain safety hazards under the long-term load.

As shown in Figure 2-3: it is the sealing and grouting device of the present invention, which includes more than one grouting bottom pipe 4, and foundation piles 10, cover plates 12 and rafts 1 arranged in sequence from bottom to top.

The foundation pile 10 comprises a primary pouring pile body 11 and a secondary pouring pile top 9, the primary pouring pile body 11 and the secondary pouring pile top 9 are connected and fixed by the main reinforcement 8; the secondary pouring pile top 9 and the cover plate The cavity formed between 12 is the pile top cavity 2, and more than one pile top support 3 is built in the pile top cavity 2, the top of the pile top support 3 is connected to the cover plate 12, and the bottom is connected to the secondary pouring pile top 9; The top surface of the cover plate 12 is connected to the bottom of the raft 1, and the side surface of the cover plate 12 is wrapped by the foundation soil layer 6 and the concrete cushion layer 5. The concrete cushion layer 5 and the foundation soil layer 6 are stacked and arranged from top to bottom. The gap between the side of the plate 12 and the concrete cushion 5 and the foundation soil layer 6 is filled with sand 7; the grouting bottom pipe 4 includes a pipe body, a grout inlet and a grout outlet at both ends of the pipe body; The grout inlet is connected with the outside, after the pipe body penetrates the pile top 9 after secondary pouring, the grout outlet is inserted into the pile top cavity 2, and the grouting bottom pipe 4 and the main reinforcement 8 are welded firmly.

The foundation form of the building should be a composite pile foundation, and the pile top support 3 is an elastic support. After the later settlement is stable, the pile top cavity 2 needs to be sealed and filled.

The top surface of the primary pouring pile body 11 is located 20cm-30cm below the surface of the concrete cushion 5, and the top surface of the secondary pouring pile top 9 is located 5cm-10cm below the surface of the concrete cushion 5.

The body of the grouting bottom pipe 4 is located 5cm-15cm below the surface 9 of the secondary pouring pile, and the grouting outlet of the grouting bottom pipe 4 is inserted into the pile top cavity 2 by 5cm-10cm. .

The inner diameter of the grouting bottom pipe 4 is 2.5 cm, 3.2 cm or 4.0 cm. The grouting bottom pipe outside the foundation pile 10 is located in the shallow layer of the foundation soil 6 and led out to the ground from the side of the raft 1 .

Claims (4)

1. a kind of constructing device filled for composite pile foundation stake top cavity envelope, it is characterised in that：Include one or more slip casting Bottom tube, and foundation pile, cover board and the raft plate sequentially arranged from the bottom to top；

The foundation pile includes that one-time-concreting pile body pours stake top with secondary, and the one-time-concreting pile body passes through with the secondary stake top that pours Main reinforcement is connected and fixed；

The secondary cavity formed between stake top and cover board that pours is stake top cavity, more than one stake top built in stake top cavity Bearing, the top connecting cover plate of stake top bearing, bottom connect second pouring stake top；

The cover board top surface is connect with raft board bottom portion, and the side of cover board is wrapped up by foundation soil and concrete cushion, concrete mats Layer, foundation soil from top to bottom stack arrangement, and the gap location between the side and concrete cushion and foundation soil of cover board passes through Back-up sand is tamped；

The slip casting bottom tube includes pipe shaft, stock inlet and grout outlet positioned at pipe shaft both ends；Stock inlet is connected to outside, and pipe shaft passes through Wear it is secondary pour stake top after, grout outlet is inserted into stake top cavity, slip casting bottom tube and main reinforcement firm welding.

2. a kind of constructing device filled for composite pile foundation stake top cavity envelope according to claim 1, it is characterised in that： One-time-concreting pile body top surface is located at 20cm-30cm under concrete cushion, and the secondary stake top face that pours is located at concrete mats The lower 5cm-10cm of layer；The slip casting bottom tube pipe shaft pours stake top lower part 5cm-15cm, the slip casting bottom tube grout outlet positioned at secondary It is inserted into cavity inside 5cm-10cm.

3. a kind of constructing device filled for composite pile foundation stake top cavity envelope according to claim 1, it is characterised in that： The slip casting bottom tube internal diameter is 2.5cm, 3.2cm or 4.0cm.

4. a kind of constructing device filled for composite pile foundation stake top cavity envelope according to claim 1, it is characterised in that： The slip casting bottom tube pipe shaft also extends through foundation soil, and leads to ground by raft plate side and be connected to outside.