Cast-in-place pile construction method

Abstract

This invention discloses a method for constructing cast-in-place piles, comprising: vertically lowering a first casing at a designated pile location; drilling a hole inside the first casing and removing mud and debris from it; filling the first casing with crushed stone filler and compacting it with vibration to form a first dense filler layer; coaxially lowering a second casing inside the first casing; filling the space between the first and second casings with crushed stone filler and compacting it with vibration to form a ring-shaped second dense filler layer; installing a reinforcing cage inside the second casing; injecting concrete grout into the second casing while simultaneously pulling it upwards until the concrete grout injection is complete and the second casing is completely pulled out of the soil layer to form the main pile body. This invention effectively prevents concrete grout from seeping into the outer soil layer during injection and solidification, thereby improving the pile body strength.

Description

Technical Field

[0001] This invention relates to the field of building construction technology. More specifically, this invention relates to a method for constructing cast-in-place piles. Background Technology

[0002] Cast-in-place piles are a widely used type of pile foundation in building construction for reinforcing the foundation. Based on their drilling methods, cast-in-place piles can be classified into driven cast-in-place piles, drilled cast-in-place piles, and manually excavated cast-in-place piles. The construction of drilled cast-in-place piles involves: first, embedding a casing at the designated pile location; then, drilling and cleaning the casing; next, placing a reinforcing cage inside the casing; and finally, simultaneously pouring concrete and pulling out the casing until the concrete pouring is complete and the casing is fully removed. However, when the soil layer outside the casing is loose or has cracks, a significant amount of concrete will seep into the soil layer outside the casing, reducing the strength of the cast-in-place pile. Summary of the Invention

[0003] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0004] Another objective of this invention is to provide a method for constructing cast-in-place piles that can effectively prevent concrete grout from seeping into the outer soil layer during the grouting and solidification process, thereby improving the strength of the cast-in-place pile.

[0005] To achieve these objectives and other advantages according to the present invention, a method for constructing cast-in-place piles is provided, comprising the following steps:

[0006] Step 1: Vertically lower the first casing at the designated pile location until its bottom is at the designed depth of the soil layer; then drill a hole inside the first casing using a drilling rig and remove the mud and debris inside the first casing.

[0007] Step 2: Fill the first casing with crushed stone filler and compact it with vibration to form the first dense filler layer;

[0008] Step 3: Lower the second casing coaxially inside the first casing until its bottom is located within the first dense packing layer;

[0009] Step 4: Fill the space between the first and second casings with crushed stone filler and compact it with vibration to form a ring-shaped second dense filler layer. The filling of the second dense filler layer is carried out in multiple unit layers. After each unit layer is filled, the first casing is pulled upwards while being compacted with vibration until the bottom of the first casing is level with the top of the unit layer below. The top of the last unit layer is level with the ground. After the last unit layer is filled, the first casing is completely pulled out of the soil layer while being compacted with vibration.

[0010] Step 5: Install the reinforcing cage inside the second casing;

[0011] Step 6: Pour concrete grout into the second casing while simultaneously pulling it up until the concrete grout pouring is complete and the second casing is completely pulled out of the soil layer to form the main pile body.

[0012] Preferably, in step 3, after the second casing is lowered, an even number of vertical grouting pipes are evenly spaced along the circumference between the first and second casings. The bottom of each grouting pipe is located within the first dense filler layer, and the top is flush with the ground. Multiple grouting hole groups are evenly spaced along the axial direction of each grouting pipe, and the multiple grouting holes of each grouting hole group are evenly spaced along the circumference of the grouting pipe.

[0013] In step 4, before filling each unit layer, a grouting assembly is placed between the first and second casings. The grouting assembly includes multiple horizontal grouting discs and multiple horizontal collars. A collar is set between any two adjacent grouting discs, and any two adjacent grouting discs are connected to the collars by a horizontal arc-shaped pipe. Each grouting disc is an annular hollow structure formed by a top plate, a bottom plate, and a side plate. The center of each arc-shaped pipe is located on the axis of the second casing. One end of each arc-shaped pipe is connected to the interior of the corresponding grouting disc, and the other end is sealed to the corresponding collar. A grouting disc / collar is fitted on each grouting pipe, and the interior of each grouting disc is connected to at least one group of grouting holes of the corresponding grouting pipe.

[0014] In step 6, while pouring concrete grout into the second casing, high-pressure grouting is used to pour concrete grout into each grouting pipe until the concrete grout in each grouting pipe is fully poured to form a side pile network.

[0015] Preferably, the grouting assembly also includes multiple tapered pipes, each arc-shaped pipe having a tapered pipe connected to it, each tapered pipe being radially parallel to the second casing, and one end of each tapered pipe being open and in contact with the side wall of the second casing.

[0016] Preferably, the sidewall of each grouting disc contacts the second casing, and two through holes are arranged at radial intervals along the sidewall of each grouting disc along the second casing.

[0017] Preferably, eight grouting pipes are evenly spaced circumferentially between the first and second casings.

[0018] Preferably, the distance between the bottom of the second casing and the top surface of the compacted base layer, and the distance between the bottom of each grouting pipe and the top surface of the compacted base layer are both 1 to 1.5 m.

[0019] Preferably, the multiple grouting discs of any two adjacent grouting components are arranged in a staggered manner.

[0020] Preferably, in the grouting assembly, the two conical tubes between any two adjacent grouting discs are arranged at uniform intervals.

[0021] The present invention has at least the following beneficial effects:

[0022] I. In this invention, crushed stone filler is filled into the first casing and vibrated and compacted to form a first dense filler layer. Then, a second casing is sunk into the first casing, and crushed stone filler is filled between the first and second casings and vibrated and compacted to form a second dense filler layer. The first and second dense filler layers can effectively prevent concrete grout from seeping into the outer soil layer during the grouting and solidification process, thereby improving the strength of the cast-in-place pile.

[0023] Second, in this invention, an even number of grouting pipes are arranged between the first and second casings. Before each unit layer of the second dense filler layer is filled, a grouting assembly is placed between the first and second casings. The grouting assembly includes multiple grouting discs, multiple collars, and multiple arc-shaped pipes. Each grouting pipe is fitted with a grouting disc / collar. When high-pressure grouting concrete is injected into each grouting pipe, the concrete grout is injected from the grouting hole on the grouting pipe into the corresponding grouting disc, and then from the grouting disc into the corresponding pipe. After the concrete grout in each grouting pipe is filled, the concrete grout will fill each grouting pipe and each grouting assembly, and solidify to form a side pile network, which can effectively improve the strength of the second dense filler layer and improve the pile strength of the cast-in-place pile.

[0024] Third, the grouting assembly in this invention also includes multiple tapered pipes, with a tapered pipe connected to each arc-shaped pipe. When high-pressure injection of concrete grout into each grouting pipe, the concrete grout injected into the pipe will be injected into the corresponding tapered pipe and merge with the concrete grout injected into the second casing from one end of the tapered pipe. After the concrete grout solidifies, it connects the side pile mesh with the main pile body, strengthens the connection between the second dense filler layer and the main pile body, and further improves the pile strength of the cast-in-place pile.

[0025] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the cast-in-place pile according to one of the technical solutions of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the construction of steps 1 to 3 of one of the technical solutions of the present invention;

[0028] Figure 3 This is a schematic diagram of step 4, layered construction, of one of the technical solutions of the present invention;

[0029] Figure 4This is a schematic diagram illustrating steps 5-6 of one of the technical solutions of the present invention.

[0030] Figure 5 This is a schematic diagram of the grouting assembly according to one of the technical solutions of the present invention;

[0031] Figure 6 This is a top view of two adjacent grouting components according to one of the technical solutions of the present invention;

[0032] Figure 7 This is a schematic diagram of the grouting disc structure according to one of the technical solutions of the present invention;

[0033] Explanation of reference numerals in the attached drawings: 1. Soil layer; 2. First casing; 3. First compacted fill layer; 4. Second casing; 5. Second compacted fill layer; 6. Unit layer; 7. Reinforcing cage; 8. Main pile body; 9. Grouting pipe; 10. Grouting plate; 11. Collar; 12. Pipe; 13. Top plate; 14. Bottom plate; 15. Side plate; 16. Side pile mesh; 17. Conical pipe; 18. Through hole. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0035] It should be noted that in the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] like Figures 1-7 As shown, the present invention provides a method for constructing cast-in-place piles, comprising the following steps:

[0037] Step 1: Vertically lower the first casing 2 at the designated pile location until its bottom is at the designed depth of soil layer 1; then drill a hole inside the first casing 2 using a drilling rig and remove the mud and debris inside the first casing 2.

[0038] Step 2: Fill the first casing 2 with crushed stone filler and compact it with vibration to form the first dense filler layer 3;

[0039] Step 3: The second casing 4 is coaxially lowered inside the first casing 2 until its bottom is located inside the first dense packing layer 3;

[0040] Step 4: Fill the space between the first casing 2 and the second casing 4 with crushed stone filler and compact it with vibration to form a ring-shaped second dense filler layer 5. The filling of the second dense filler layer 5 is carried out in multiple unit layers 6. After each unit layer 6 is filled, the first casing 2 is pulled upwards while being compacted with vibration until the bottom of the first casing 2 is level with the top of the unit layer 6 below it. The top of the last unit layer 6 is level with the ground. After the last unit layer 6 is filled, the first casing 2 is completely pulled out of the soil layer 1 while being compacted with vibration.

[0041] Step 5: Install the reinforcing cage 7 inside the second casing 4;

[0042] Step 6: Pour concrete grout into the second casing 4 and simultaneously pull up the second casing 4 until the concrete grout pouring is completed and the second casing 4 is completely pulled out from the soil layer 1 to form the main pile body 8, thus completing the construction of the cast-in-place pile at this pile location.

[0043] In the above technical solution, the first dense filler layer 3 inside the first casing 2 provides a supporting foundation for the sinking of the second casing 4, making the second casing 4 more stable, and effectively preventing concrete grout from overflowing from the bottom of the second casing 4; the second dense filler layer 5 between the first casing 2 and the second casing 4 surrounds the side wall of the second casing 4, effectively preventing concrete grout from seeping into the outer soil layer 1; the first dense filler layer 3 and the second dense filler layer 5 form a grouting groove with an open upper end and a hollow cylindrical structure. When concrete grout is injected into the second casing 4 and the second casing 4 is pulled up, the concrete grout is injected into the grouting groove. The main pile body 8 is formed by solidifying the concrete grout in the grouting trench, which effectively prevents the concrete grout from seeping into the outer soil layer 1 during the grouting and solidification process, thereby improving the strength of the cast-in-place pile. Moreover, dividing the second dense filler layer 5 into multiple unit layers 6 for filling and vibration compaction can improve the density of the second dense filler layer 5, which is beneficial to further prevent the concrete grout from seeping into the outer soil layer 1 and to improve the strength of the cast-in-place pile. In addition, the inner diameter of the second casing 4 is preferably 0.7 to 0.8 times the inner diameter of the first casing 2, which, while preventing the concrete grout from seeping into the outer soil layer 1, also ensures the strength of the cast-in-place pile.

[0044] In another technical solution, in step 3, after the second casing 4 is lowered, an even number of vertical grouting pipes 9 are evenly spaced along the circumference between the first casing 2 and the second casing 4. The bottom of each grouting pipe 9 is located within the first dense filler layer 3, and the top is flush with the ground. Multiple grouting hole groups are evenly spaced along the axial direction on each grouting pipe 9, and the multiple grouting holes of each grouting hole group are evenly spaced along the circumference of the grouting pipe 9.

[0045] In step 4, before filling each unit layer 6, a grouting assembly is placed between the first casing 2 and the second casing 4. The grouting assembly includes multiple horizontal grouting discs 10 and multiple horizontal collars 11. A collar 11 is placed between any two adjacent grouting discs 10, and any adjacent grouting discs 10 and collars 11 are connected by a horizontal arc-shaped pipe 12. Each grouting disc 10 is an annular hollow structure formed by a top plate 13, a bottom plate 14, and a side plate 15. Each arc-shaped pipe 12... The center of the circle is located on the axis of the second casing 4. One end of each arc-shaped pipe 12 is connected to the interior of the corresponding grouting plate 10, and the other end is sealed to the corresponding collar 11. Each grouting pipe 9 is fitted with a grouting plate 10 / collar 11 (each grouting plate 10 is fitted on a grouting pipe 9, and each collar 11 is fitted on a grouting pipe 9). The interior of each grouting plate 10 is connected to at least one grouting hole group of the corresponding grouting pipe 9. The inner diameter of the grouting plate 10 is adapted to the outer diameter of the grouting pipe 9.

[0046] In step 6, while pouring concrete grout into the second casing 4, high-pressure grouting is used to pour concrete grout into each grouting pipe 9 until the concrete grout in each grouting pipe 9 is fully poured to form the side pile network 16.

[0047] When high-pressure injection of concrete grout into each grouting pipe 9, the concrete grout is injected from the grouting hole on the grouting pipe 9 into the corresponding grouting plate 10, and then from the grouting plate 10 into the corresponding pipe 12. After the concrete grout in each grouting pipe 9 is completed, the concrete grout will fill each grouting pipe 9 and each grouting component, and solidify to form a side pile network 16, which can effectively improve the strength of the second dense filler layer 5 and improve the pile strength of the cast-in-place pile. At the same time, the concrete grout will also seep into the second dense filler layer 5 from the grouting hole on the grouting pipe 9, further improving the strength of the second dense filler layer 5. In addition, the multiple grouting plates 10 and multiple collars 11 in the grouting component are arranged at intervals, which can realize the staggered arrangement of multiple grouting plates 10 in two adjacent grouting components, so that all the grouting plates 10 in the second dense filler layer 5 are arranged in a spiral shape, which reduces the amount of grouting plates 10 and concrete grout used, while further improving the strength of the second dense filler layer 5. In another technical solution, the grouting assembly also includes a plurality of tapered pipes 17, each of the arc-shaped pipes 12 is provided with a tapered pipe 17 communicating with it, each tapered pipe 17 is radially parallel to the second casing 4, one end of each tapered pipe 17 is open and contacts the side wall of the second casing 4.

[0048] When high-pressure injection of concrete grout into each grouting pipe 9, the concrete grout in the injection pipe 12 will be injected into the corresponding tapered pipe 17 and merge with the concrete grout injected into the second casing 4 from one end of the tapered pipe 17. After the concrete grout solidifies, it connects the side pile mesh 16 with the main pile body 8, strengthens the connection between the second dense filler layer 5 and the main pile body 8, and further improves the pile strength of the cast-in-place pile.

[0049] In another technical solution, the sidewall of each grouting plate 10 contacts the second casing 4, and two through holes 18 are arranged radially at intervals along the second casing 4 on the side plate 15 of each grouting plate 10. When high-pressure injection of concrete grout into each grouting pipe 9, the concrete grout injected into the grouting plate 10 overflows from the two through holes 18. The concrete grout overflowing from one of the through holes 18 merges with the concrete grout injected into the second casing 4, which can strengthen the connection between the side pile mesh 16 and the main pile 8. The concrete grout overflowing from the other through hole 18 seeps into the second dense filler layer 5, which can improve the strength of the second dense filler layer 5; together, they improve the pile strength of the cast-in-place pile.

[0050] In another technical solution, eight grouting pipes 9 are evenly spaced circumferentially between the first casing 2 and the second casing 4. A more suitable number of grouting pipes 9 is beneficial to ensuring the strength of the cast-in-place pile.

[0051] In another technical solution, the distance between the bottom of the second casing 4 and the top surface of the compacted base layer, and the distance between the bottom of each grouting pipe 9 and the top surface of the compacted base layer, are both 1 to 1.5 meters. This prevents concrete grout from overflowing from the bottom of the second casing 4 and the bottom of each grouting pipe 9, while ensuring the stability of the installation of the second casing 4 and each grouting pipe 9.

[0052] In another technical solution, multiple grouting discs 10 of any two adjacent grouting components are staggered. This allows all grouting discs 10 and all tapered tubes 17 within the second dense filler layer 5 to be arranged in a spiral pattern. This reduces the amount of grouting discs 10, tapered tubes 17, and concrete grout used, while further improving the strength of the second dense filler layer 5 and strengthening the connection between the side pile network 16 and the main pile body 8, thereby increasing the pile strength of the cast-in-place pile.

[0053] In another technical solution, in the grouting assembly, two tapered tubes 17 are evenly spaced between any two adjacent grouting discs 10. The even arrangement of multiple tapered tubes 17 in the grouting assembly can further ensure the strength of the cast-in-place pile.

[0054] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for constructing cast-in-place piles, characterized in that, Includes the following steps: Step 1: Vertically lower the first casing at the designated pile location until its bottom is at the designed depth of the soil layer; then drill a hole inside the first casing using a drilling rig and remove the mud and debris inside the first casing. Step 2: Fill the first casing with crushed stone filler and compact it with vibration to form the first dense filler layer; Step 3: Lower the second casing coaxially inside the first casing until its bottom is located within the first dense packing layer; Step 4: Fill the space between the first and second casings with crushed stone filler and compact it with vibration to form a ring-shaped second dense filler layer. The filling of the second dense filler layer is carried out in multiple unit layers. After each unit layer is filled, the first casing is pulled upwards while being compacted with vibration until the bottom of the first casing is level with the top of the unit layer below. The top of the last unit layer is level with the ground. After the last unit layer is filled, the first casing is completely pulled out of the soil layer while being compacted with vibration. Step 5: Install the reinforcing cage inside the second casing; Step 6: Pour concrete grout into the second casing and simultaneously pull up the second casing until the concrete grout pouring is completed and the second casing is completely pulled out of the soil layer to form the main pile body. In step 3, after the second casing is lowered, an even number of vertical grouting pipes are evenly spaced along the circumference between the first and second casings. The bottom of each grouting pipe is located within the first dense filler layer, and the top is flush with the ground. Multiple grouting hole groups are evenly spaced along the axial direction of each grouting pipe, and the multiple grouting holes of each grouting hole group are evenly spaced along the circumference of the grouting pipe. In step 4, before filling each unit layer, a grouting assembly is placed between the first and second casings. The grouting assembly includes multiple horizontal grouting discs and multiple horizontal collars. A collar is set between any two adjacent grouting discs, and any two adjacent grouting discs are connected to the collars by a horizontal arc-shaped pipe. Each grouting disc is an annular hollow structure formed by a top plate, a bottom plate, and a side plate. The center of each arc-shaped pipe is located on the axis of the second casing. One end of each arc-shaped pipe is connected to the interior of the corresponding grouting disc, and the other end is sealed to the corresponding collar. A grouting disc / collar is fitted on each grouting pipe, and the interior of each grouting disc is connected to at least one group of grouting holes of the corresponding grouting pipe. In step 6, while pouring concrete grout into the second casing, high-pressure grouting is used to pour concrete grout into each grouting pipe until the concrete grout in each grouting pipe is completely poured to form a side pile network. The grouting assembly also includes multiple tapered pipes, each arc-shaped pipe having a tapered pipe connected to it, each tapered pipe being radially parallel to the second casing, and one end of each tapered pipe being open and in contact with the side wall of the second casing; Each grouting plate has its sidewall in contact with the second casing, and two through holes are arranged radially at intervals along the sidewall of each grouting plate.

2. The method for constructing cast-in-place piles as described in claim 1, characterized in that, Eight grouting pipes are evenly spaced circumferentially between the first and second casings.

3. The method for constructing cast-in-place piles as described in claim 1, characterized in that, The distance between the bottom of the second casing and the top surface of the compacted base layer, and the distance between the bottom of each grouting pipe and the top surface of the compacted base layer are both 1~1.5 m.

4. The method for constructing cast-in-place piles as described in claim 1, characterized in that, Multiple grouting discs of any two adjacent grouting components are staggered.

5. The method for constructing cast-in-place piles as described in claim 1, characterized in that, In the grouting assembly, two tapered tubes are evenly spaced between any two adjacent grouting discs.

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