Umbrella rib type grouting expanded-base bag structure of precast pile bottom and construction method of umbrella rib type grouting expanded-base bag structure

Abstract

The invention discloses an umbrella rib type grouting expanded-base bag structure for the bottom of a precast pile and a construction method of the umbrella rib type grouting expanded-base bag structure. In the umbrella rib type grouting expanded-base bag structure, a plurality of bag structure framework rods which are arranged at intervals along the circumference are installed between an upper framework connecting disc and a lower framework connecting disc, a reducer union is installed on the upper framework connecting disc, and a jacking steel pipe is installed on the lower surface of the upper framework connecting disc among the plurality of bag structure framework rods. A chassis is arranged under the lower framework connecting disc, the lower end of the jacking steel pipe is coaxially sleeved with a supporting steel pipe, the lower end of the jacking steel pipe and the upper end of the supporting steel pipe can move, and the lower end of the supporting steel pipe penetrates through a through hole in the middle of the lower framework connecting disc and then is fixedly connected with the upper surface of the chassis. A bag is arranged outside the bag structure framework rod, the top of the bag is closed to the bottom of the reducer union, and the bottom of the bag is closed to the upper surface of the base plate. The structure is easy to construct, the pile end bearing capacity of the precast pile can be greatly improved, and the load bearing capacity of the precast pile is improved.

Description

Technical Field

[0001] The invention relates to a grouting expansion structure for a precast pile bottom in the field of foundation pit support structures, and in particular to an umbrella-shaped grouting bottom expansion bag structure for a precast pile bottom and a construction method. Background Art

[0002] In the field of engineering construction, with the continuous advancement and improvement of technological processes and machinery, the styles and types of foundation pit support structures are showing a trend of diversification. Precast concrete square piles (hereinafter referred to as "precast piles") are gradually being used in foundation pit support projects due to their significant advantages, such as flexible layout, material conservation, convenient excavation, and shortened construction time. However, the use and promotion of precast piles have encountered the following problems and challenges: ① When the precast pile application range contains relatively hard soil layers or highly permeable sandy soil layers, the precast piles have difficulty penetrating the soil and cannot be constructed to the designed depth. Forcibly increasing the power of the construction machinery to drive the precast piles can cause cracking or even breakage of the precast pile shaft. ② When the precast pile application range contains deep, weak soil layers, the design length of the pile shaft is generally longer to ensure that the pile shaft can provide sufficient side friction. However, a longer pile shaft reduces the economic feasibility of precast piles, limiting their application scenarios and scope. To solve the above problems, the conventional measure currently adopted is to pre-install grouting pipes in the cavity of precast piles. When the pile end reaches the designed depth, grouting is injected into the pile bottom through high-pressure equipment. However, this measure does not have a bag structure, and the grouting volume and grouting molding effect are uncontrollable, which increases the implementation cost. Summary of the Invention

[0003] The purpose of the present invention is to address the current problems of being unable to effectively control the grouting process at the bottom of precast piles, and the grouting volume and grouting effect not meeting the standards, and propose an umbrella-shaped grouting and bottom-expanding bag structure and construction method for the bottom of precast piles. The present invention utilizes a fully hydraulic static pile driver, high-pressure rotary jet mixing equipment, and an umbrella-shaped grouting and bottom-expanding bag structure at the bottom of precast piles to press the precast pile to the designed depth and then eject the bag structure. After the bag is ejected, it expands to form an umbrella-shaped bag structure with controllable grouting volume and diameter, providing the precast pile with sufficient and effective pile end bearing capacity. At the same time, it can further shorten the design length of the precast pile, reduce construction costs, and improve construction efficiency. The present invention has simple construction steps, reasonable and effective design, and simple construction operation, which well compensates for the shortcomings of the existing precast pile bottom grouting technology.

[0004] In order to achieve the purpose, the technical solution provided by the present invention is: 1. An umbrella-shaped grouting and bottom-expanding bag structure at the bottom of a prefabricated pile The umbrella-rib-shaped grouting bottom expansion bag structure includes a reducer, an upper skeleton connecting plate, a bag structure skeleton rod, a jacking steel pipe, a support steel pipe, a lower skeleton connecting plate, a chassis and a bag; a plurality of bag structure skeleton rods arranged along the circumference are installed between the upper skeleton connecting plate and the lower skeleton connecting plate, a reducer is installed on the upper skeleton connecting plate, the upper end of the jacking steel pipe is fixedly installed on the lower surface of the upper skeleton connecting plate between the plurality of bag structure skeleton rods, a chassis is provided directly below the lower skeleton connecting plate, a support steel pipe is coaxially sleeved outside the lower end of the jacking steel pipe, the lower end of the jacking steel pipe and the upper end of the support steel pipe are movable between each other, and the lower end of the support steel pipe is fixedly connected to the upper surface of the chassis after passing through the through hole in the middle of the lower skeleton connecting plate; a bag is provided outside the bag structure skeleton rod, the top of the bag closes to the bottom of the reducer, and the bottom of the bag closes to the upper surface of the chassis.

[0005] A through hole is provided in the middle of the upper skeleton connecting plate, and a through hole is also provided in the bottom of the reducer. The middle through hole of the upper skeleton connecting plate is communicated with the bottom through hole of the reducer.

[0006] The jacking steel pipe is tightly connected to the upper skeleton connecting plate through a sealing ring.

[0007] The upper skeleton connecting plate includes a first steel plate and an axis groove. The lower surface of the first steel plate is provided with a plurality of axis grooves arranged at intervals along the circumference. Each axis groove is hinged to the top end of the corresponding bag structure skeleton rod.

[0008] The lower skeleton connecting plate includes a second steel plate and an axis groove. The upper surface of the second steel plate is provided with a plurality of axis grooves arranged at intervals along the circumference. Each axis groove is hinged to the bottom end of the corresponding bag structure skeleton rod.

[0009] Each of the bag structure skeleton rods includes a first connecting rod and a second connecting rod hingedly connected up and down.

[0010] A grouting port is provided on the top of the bag.

[0011] A through hole is provided in the middle of the chassis.

[0012] The length of the jacking steel pipe is less than, equal to or greater than the length of the supporting steel pipe.

[0013] 2. Construction method of umbrella-shaped grouting and bottom-expanding bag structure at the bottom of prefabricated piles 1) Preparation: Place the umbrella-shaped grouting and bottom-expanding bag structure inside the bottom of the precast pile so that the chassis is in close contact with the bottom of the precast pile. Install a grouting pipe on the top of the bag, and extend the grouting pipe upward from the inside of the precast pile to the top of the precast pile. 2) Using a fully hydraulic static pile driver, press the prefabricated pile equipped with an umbrella-shaped grouting and bottom-expanding bag structure to the preset position; 3) The rotary grouting equipment is equipped with a combination drill rod, and the rotary grouting equipment is hoisted onto the fully hydraulic static pile driver 12; the position of the combination drill rod in the rotary grouting equipment is adjusted so that the drill rod with a smaller diameter in the combination drill rod passes through the jacking steel pipe and the support steel pipe, and the drill rod with a larger diameter is close to the reducing part of the reducer 1; 4) Start the rotary grouting equipment and perform the grouting operation by drilling the slurry to mix and grout the soil around the bottom of the precast pile; 5) After the grouting body of the soil around the pile bottom is formed, the combined drill rod of the rotary grouting mixing equipment is driven downward to push the umbrella-shaped grouting bottom expansion bag structure out of the pile bottom of the precast pile until the jacking process is completed; 6) Grouting is performed through the grouting pipe to fill the bag. After grouting, the bag is tightly combined with the bottom of the precast pile and the surrounding soil.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) By jacking the umbrella-shaped grouting bottom expansion bag structure at the bottom of the precast pile, a complete pile end bearing body can be formed at the bottom of the precast pile, which is simple and efficient in construction and has a high forming rate; (2) The umbrella-shaped grouting expansion bag structure at the bottom of the precast pile forms a stable umbrella-shaped structure after grouting, which greatly increases the bearing capacity of the precast pile end and improves the load-bearing capacity of the precast pile, and can provide greater lateral support for the foundation pit retaining system; (3) Adding an umbrella-shaped grouting bottom expansion bag structure to the bottom of the precast pile can effectively shorten the length of the precast pile, reduce the construction cost of the project, and improve the economic benefits of the project; (4) The umbrella-shaped grouting bottom expansion bag structure at the bottom of the precast pile can effectively control the grouting volume and grouting molding effect, without slurry leakage, and significantly improve the bearing capacity of the precast pile, with good economic benefits; (5) The umbrella-shaped grouting bottom expansion bag structure at the bottom of the precast pile adopts an umbrella-shaped opening method. The bearing capacity of the precast pile end is proportional to the size of the frame opening. The increase in the pile end bearing capacity can be adjusted by adjusting the length of the bag structure frame rod, achieving controllable design and controllable adjustment; (6) The precast piles are supported by a fully hydraulic static pile driver and high-pressure rotary jet mixing equipment. The pile driving angle is kept consistent with the grouting angle, so that the end bearing force of the bag can be more fully exerted, greatly improving the bearing capacity of the precast piles. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a structural diagram of an umbrella-rib type grouting bottom expansion bag structure; Figure 2 This is an exploded view of the umbrella rib type grouting bottom expansion bag structure; Figure 3 This is a diagram of the placement of the umbrella-shaped grouting and bottom-expanding bag structure in the prefabricated pile; Figure 4Schematic diagram of the structure of the upper skeleton connecting plate; Figure 5 This is a schematic diagram of the structure of the skeleton rod of the capsule structure; Figure 6 1 is a schematic structural diagram of the lower skeleton connecting plate; Figure 7 This is a schematic diagram of the ejection of the umbrella-rib type grouting bottom expansion bag structure; Figure 8 This is a schematic diagram of a fully hydraulic static pile driver driving precast piles; Figure 9 It is a schematic diagram of high-pressure rotary jet mixing equipment and combined drill pipe; Figure 10 This is a schematic diagram of the installation of high-pressure jet grouting equipment on a fully hydraulic static pile driver; Figure 11 This is a schematic diagram of the location of the high-pressure rotary jet mixing equipment for rotary jet grouting; Figure 12 This is a schematic diagram of high-pressure rotary spray mixing equipment for rotary spray grouting molding; Figure 13 This is a schematic diagram of the umbrella-shaped grouting bottom expansion bag structure in the grouting body after being ejected; In the figure: 1. Reducer, 2. Upper skeleton connecting plate, 2-1. First steel plate, 2-2. Shaft groove, 3. Sealing ring, 4. Bladder structure skeleton rod, 4-1. First connecting rod, 4-2. Second connecting rod, 5. Jacking steel pipe, 6. Support steel pipe, 7. Lower skeleton connecting plate, 7-1. Second steel plate, 8. Chassis, 9. Bladder, 10. Grouting pipe, 11. Precast pile, 12. Fully hydraulic static pile driver, 13. Rotary grouting equipment, 14. Combined drill pipe, 14-1. First drill pipe, 14-2. Second drill pipe, 15. Grouting body. DETAILED DESCRIPTION

[0016] In order to further understand the content of the present invention, the present invention is described in detail with reference to the examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0017] The cross-sectional dimensions of the prefabricated piles used are 400mm×400mm, and the hollow circle diameter is 250mm.

[0018] like Figure 1 and Figure 2As shown, the umbrella-rib-shaped grouting bottom expansion bag structure for the base of a precast pile proposed by the present invention includes a reducer 1, an upper frame connection plate 2, bag structure frame rods 4, a jacking steel pipe 5, a support steel pipe 6, a lower frame connection plate 7, a base plate 8, and a bag 9. Several bag structure frame rods 4 are installed between the upper frame connection plate 2 and the lower frame connection plate 7, arranged at equal intervals along the circumference. The reducer 1 is installed on the upper frame connection plate 2. The upper end of the jacking steel pipe 5 is fixedly mounted on the lower surface of the upper frame connection plate 2 between the several bag structure frame rods 4. The base plate 8 is located directly below the lower frame connection plate 7. The lower frame connection plate 7 is welded to the support steel pipe 6, and the welding position is approximately 10 cm from the base plate 8. The base plate 8 is 10 mm thick, with an outer diameter of 450 mm and an inner diameter of 65 mm. The lower end of the jacking steel pipe 5 is coaxially sleeved with a support steel pipe 6. The lower end of the jacking steel pipe 5 and the upper end of the support steel pipe 6 are movable. The ejection schematic diagram of the umbrella-shaped grouting bottom expansion bag structure is shown in FIG. Figure 7 As shown. The diameter of the jacking steel pipe 5 is 48mm and the wall thickness is 5mm. The diameter of the supporting steel pipe 6 is 65mm and the wall thickness is 5mm. The lower end of the supporting steel pipe 6 passes through the through hole in the middle of the lower skeleton connecting plate 7 and is fixedly connected to the upper surface of the chassis 8; a bag 9 is provided outside the bag structure skeleton rod 4, and the top of the bag 9 is closed to the bottom of the reducer 1, and the bottom of the bag 9 is closed to the upper surface of the chassis 8. The bag 9 is made of canvas or geotextile. The bag 9 needs to be tightly connected, without looseness and leakage points, while maintaining a certain stretching space to support the expansion of the skeleton structure.

[0019] A through-hole is formed in the center of the first steel plate 2-1 of the upper frame connection plate 2, and a through-hole is also formed in the bottom of the reducer 1. The through-hole in the center of the first steel plate 2-1 of the upper frame connection plate 2 communicates with the through-hole in the bottom of the reducer 1. The upper surface of the first steel plate 2-1 is welded to the bottom of the reducer 1, aligned with the weld seam. The reducer 1 has an upper diameter of 150 mm and a lower diameter of 48 mm.

[0020] The jacking steel pipe 5 is arranged in the middle through hole of the first steel plate 2 - 1 , and the jacking steel pipe 5 is tightly connected to the first steel plate 2 - 1 of the upper skeleton connecting plate 2 through the sealing ring 3 .

[0021] like Figure 4 (a) and Figure 4 As shown in (b), the upper frame connecting plate 2 comprises a first steel plate 2-1 and an arcuate shaft slot 2-2. The lower surface of the first steel plate 2-1 is provided with several shaft slots 2-2 spaced evenly around the circumference. Each shaft slot 2-2 is hingedly connected to the top end of a corresponding bladder structure rod 4. The outer diameter of the first steel plate 2-1 is 124 mm, and the inner diameter is 48 mm. There are six shaft slots, and the angle between the centers of adjacent shaft slots is 60°.

[0022] like Figure 6 (a) and Figure 6 As shown in (b), the lower frame connecting plate 7 comprises a second steel plate 7-1 and axle slots. The upper surface of the second steel plate 7-1 is equipped with several axle slots 2-2, spaced evenly along the circumference. Each axle slot is hingedly connected to the bottom end of a corresponding bladder structure frame rod 4. The outer diameter of the second steel plate 7-1 is 124 mm, and the inner diameter is 65 mm. There are six axle slots, and the angle between the centers of adjacent axle slots is 60°.

[0023] like Figure 5 (a) and Figure 5 As shown in (b), each bag structure skeleton rod 4 includes a first connecting rod 4-1 and a second connecting rod 4-2 hingedly connected to each other. Both ends of the first connecting rod 4-1 and the second connecting rod 4-2 are circular rings with an outer diameter of 40 mm and an inner diameter of 20 mm.

[0024] A grouting port is provided at the top of the bag 9 , and a slurry outlet end of the grouting pipe 10 enters the bag 9 from the grouting port and is disposed at the top of the bag 9 .

[0025] A through hole is provided in the middle of the chassis 8 , and the through hole in the middle of the chassis 8 is coaxially arranged with the middle through holes of the upper skeleton connecting plate 2 and the lower skeleton connecting plate 7 .

[0026] The length of the jacking steel pipe 5 is less than, equal to, or greater than the length of the supporting steel pipe 6 .

[0027] The reducer 1 is a semicircular joint with its opening facing upward.

[0028] The first steel plate, the second steel plate and the bottom plate are all circular steel plates with a through hole in the middle.

[0029] The present invention also proposes a construction method for an umbrella-shaped grouting bottom expansion bag structure at the bottom of a prefabricated pile, the construction method comprising the following steps: 1) If Figure 3 As shown, the umbrella-shaped grouting bottom expansion bag structure is placed inside the bottom of the precast pile 11, so that the chassis 8 is in close contact with the bottom of the precast pile 11, and the grouting pipe 10 is installed on the top of the bag 9. The grouting pipe 10 extends upward from the inside of the precast pile 11 to the top of the precast pile 11 to facilitate the subsequent grouting work; 2) If Figure 8 As shown, a fully hydraulic static pile driver 12 is used to press a precast pile 11 equipped with an umbrella-shaped grouting bottom expansion bag structure to a preset position and a preset depth. Specifically, the fully hydraulic static pile driver 12 is parked at the construction position by positioning and laying out the lines. The assembled precast pile 11 is placed on the fully hydraulic static pile driver 12. The fully hydraulic static pile driver 12 gradually applies oblique hydraulic pressure to press the precast pile 11 to the specified design position and depth. 3) If Figure 9 and Figure 10As shown, the high-pressure rotary grouting mixing equipment 13 is equipped with a combined drill rod 14, and the high-pressure rotary grouting mixing equipment 13 is hoisted onto the full-hydraulic static pile driver 12; Figure 11 As shown, the position of the combined drill rod 14 in the high-pressure rotary grouting mixing equipment 13 is adjusted so that the drill rod with a smaller diameter (i.e., the second drill rod 14-2 with a diameter of 30 mm) passes through the jacking steel pipe 5 and the support steel pipe 6, with the drill bit exposed for about 800 mm, and the drill rod with a larger diameter (i.e., the first drill rod 14-1 with a diameter of 63 mm) is close to the reducing portion of the reducer 1; 4) If Figure 12 As shown, the high-pressure rotary grouting equipment 13 is started to perform a grouting operation using a drill bit to stir and grout the soil around the bottom of the precast pile 11. The diameter of the grouting body 15 is about 1000 mm. 5) If Figure 13 As shown, after the grouting body 15 of the soil around the pile bottom is formed, the combined drill rod 14 of the high-pressure rotary grouting mixing equipment 13 is driven downward to push the umbrella-shaped grouting bottom expansion bag structure out of the pile bottom of the prefabricated pile 11. During the jacking process, the umbrella-shaped structure of the umbrella-shaped grouting bottom expansion bag structure is gradually expanded until the upper end of the supporting steel pipe 6 presses against the upper skeleton connection plate 2, and the jacking process is completed; 6) Grouting is performed through the grouting pipe 10 to fill the bag 9. After grouting, the bag 9 is tightly combined with the bottom of the precast pile 11 and the surrounding soil. The high-pressure rotary jet mixing equipment 13 and the combined drill pipe 14 are evacuated.

[0030] 7) After the construction of the precast piles 11 is completed, the precast piles and the retaining piles are connected to form a support structure through the construction of the top beam. After the top beam reaches the design strength, the foundation pit excavation and basement construction can be carried out.

[0031] The present invention has been described in detail above with reference to the embodiments. However, the contents described are only preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. An umbrella-shaped grouting bottom expansion bag structure at the bottom of a prefabricated pile, characterized in that: The invention comprises a reducing joint (1), an upper frame connecting plate (2), a bag structure frame rod (4), a jacking steel pipe (5), a supporting steel pipe (6), a lower frame connecting plate (7), a bottom plate (8) and a bag (9); a plurality of bag structure frame rods (4) arranged at intervals along the circumference are installed between the upper frame connecting plate (2) and the lower frame connecting plate (7); a reducing joint (1) is installed on the upper frame connecting plate (2); the upper end of the jacking steel pipe (5) is fixedly installed on the lower surface of the upper frame connecting plate (2) between the plurality of bag structure frame rods (4); A chassis (8) is provided directly below the lower frame connecting plate (7); a supporting steel pipe (6) is coaxially sleeved outside the lower end of the jacking steel pipe (5); the lower end of the jacking steel pipe (5) and the upper end of the supporting steel pipe (6) are movable; the lower end of the supporting steel pipe (6) passes through the through hole in the middle of the lower frame connecting plate (7) and is fixedly connected to the upper surface of the chassis (8); a bag (9) is provided outside the bag structure skeleton rod (4); the top of the bag (9) closes to the bottom of the reducer (1), and the bottom of the bag (9) closes to the upper surface of the chassis (8).

2. The umbrella-rib-shaped grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: A through hole is provided in the middle of the upper skeleton connection plate (2), and a through hole is also provided in the bottom of the reducer (1). The middle through hole of the upper skeleton connection plate (2) is in communication with the bottom through hole of the reducer (1).

3. The umbrella-shaped grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: The jacking steel pipe (5) is tightly connected to the upper skeleton connecting plate (2) via a sealing ring (3).

4. The umbrella-rib-shaped grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: The upper skeleton connecting plate (2) comprises a first steel plate (2-1) and an axis groove (2-2). The lower surface of the first steel plate (2-1) is provided with a plurality of axis grooves (2-2) arranged at intervals along the circumference. Each axis groove (2-2) is hinged to the top end of a corresponding bag structure skeleton rod (4).

5. The umbrella-rib type grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: The lower skeleton connecting plate (7) comprises a second steel plate (7-1) and an axis groove. The upper surface of the second steel plate (7-1) is provided with a plurality of axis grooves (2-2) arranged at intervals along the circumference. Each axis groove is hinged to the bottom end of a corresponding bag structure skeleton rod (4).

6. The umbrella-rib-shaped grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: Each of the bag structure skeleton rods (4) comprises a first connecting rod (4-1) and a second connecting rod (4-2) hingedly connected up and down.

7. The umbrella-rib-shaped grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: A grouting port is provided on the top of the bag (9).

8. The umbrella-rib-shaped grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: A through hole is provided in the middle of the chassis (8).

9. The umbrella-rib-shaped grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: The length of the jacking steel pipe (5) is less than, equal to, or greater than the length of the supporting steel pipe (6).

10. The construction method of the umbrella-rib type grouting bottom expansion bag structure at the bottom of a precast pile according to claim 1, characterized in that: The construction method comprises the following steps: 1) Preparation: The umbrella-shaped grouting bottom expansion bag structure is placed inside the bottom of the precast pile (11), so that the chassis (8) is in close contact with the bottom of the precast pile (11), and the grouting pipe (10) is installed on the top of the bag (9), and the grouting pipe (10) extends upward from the inside of the precast pile (11) to the top of the precast pile (11); 2) using a fully hydraulic static pile driver (12) to press the prefabricated pile (11) equipped with the umbrella-shaped grouting bottom expansion bag structure to a preset position; 3) The rotary grouting mixing device (13) is equipped with a combined drill rod (14), and the rotary grouting mixing device (13) is hoisted onto the fully hydraulic static pile driver 12; the position of the combined drill rod (14) in the rotary grouting mixing device (13) is adjusted so that the drill rod with a smaller diameter in the combined drill rod (14) passes through the jacking steel pipe (5) and the support steel pipe (6), and the drill rod with a larger diameter is close to the diameter reducing portion of the reducer 1; 4) starting the rotary grouting equipment (13), performing the drilling slurry delivery rotary grouting operation, and stirring and grouting the soil around the bottom of the prefabricated pile (11); 5) After the grouting body (15) of the soil around the pile bottom is formed, the combined drill rod (14) of the rotary grouting mixing equipment (13) is driven downward to push the umbrella-shaped grouting bottom expansion bag structure out of the pile bottom of the prefabricated pile (11) until the jacking process is completed; 6) Grouting is performed through the grouting pipe (10) to fill the bag (9). After grouting, the bag (9) is tightly combined with the bottom of the prefabricated pile (11) and the surrounding soil.

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