Slurry soil stratum pile foundation hole forming process

Abstract

The invention discloses a slurry soil stratum pile foundation hole-forming process. A rotary drilling machine excavates a pile hole by using a desilting and wall-fixing drill bit under the condition of no grouting; the desilting and wall-fixing drill bit comprises a drill cylinder, a cylinder body of the drill cylinder is provided with a circulation hole, the outer wall of the drill cylinder is further provided with a protruding extrusion strip, the bottom of the drill cylinder is provided with an inverted-cone-shaped cutting plate, and the bottom of the drill cylinder and the cutting plate are further provided with abrasion-resistant heads. When the desilting and wall-fixing drill bit drills downwards, on one hand, a hole is drilled through transverse pressure applied to a soil layer, on the other hand, the rotary drilling machine drives the desilting and wall-fixing drill bit to rotate through huge torsion of the rotary drilling machine and stirs soil in the hole to form slurry, and the slurry is guided into a gap between the hole wall and the outer wall of the drilling barrel; and finally, the soil is pressed on the surface of the hole wall by an extrusion strip on the outer side of the cylinder wall to form a compact and smooth clay slurry film, so that a solidified and firm pile hole is formed in a slurry soil stratum. The pile hole with high tightness can be excavated through the hole forming technology, mud pit excavation and mud preparation are not needed in the construction process, the construction efficiency can be improved, and the construction cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to pile foundation construction, in particular to a hole-forming process for drilling a pile hole in a slurry soil stratum. BACKGROUND

[0002] Rotary drilling with a rotary drilling machine is a very common hole-forming process for pile foundation construction, and the drill bit used in rotary drilling includes a screw drill bit, a barrel-type drill bucket, a rotary drill bucket, etc. For a rock-soil stratum with good cohesion, a dry drilling process or a clean water drilling process can be used; and for a stratum with a lot of silt and easy to collapse, a full protection barrel must be used many times to isolate the hole wall from the surrounding soil. The full protection barrel not only has a large length, but also needs to be gradually pressed down as the pile hole is drilled, and then pulled out while pouring concrete in the later stage. The whole construction process is relatively complicated and complex. In addition to the use of a full protection barrel, high-quality bentonite is often used to make slurry in the slurry pit to increase the viscosity of the slurry and better form a mud skin on the hole wall, but this will increase the construction cost and difficulty, and the amount of slurry needed is huge. SUMMARY

[0003] The purpose of the present application is to provide a slurry soil stratum pile foundation hole-forming process that can increase hole-forming stability and reduce the need for slurry making, to improve hole-forming quality and reduce construction difficulty.

[0004] The slurry soil stratum pile foundation hole-forming process described in the present application comprises the following steps: A. Installing a pile head outer protection barrel, pressing the pile head outer protection barrel into the ground; B. Installing an inner protection barrel, pressing the inner protection barrel into the ground on the inner side of the pile head outer protection barrel; C. Rotary drilling, the rotary drilling machine drills a pile hole through a dredging and wall stabilizing drill bit without grouting, the dredging and wall stabilizing drill bit comprises a drill barrel that is cylindrical and has openings at the top and bottom, and a connecting pipe arranged on the axis of the drill barrel, a support rod is connected between the top of the connecting pipe and the top of the drill barrel, the lower part of the connecting pipe is a central shaft, the bottom end of the central shaft protrudes from the bottom of the drill barrel, an inclined cutting plate is connected between the bottom end of the central shaft and the bottom of the drill barrel, a plurality of cutting plates are distributed circumferentially and have an inverted conical structure; a plurality of wear-resistant heads are respectively arranged on the bottom surface of the central shaft, the bottom edge of the drill barrel and the drill plate; a plurality of outward protruding extrusion strips are arranged on the outer wall of the drill barrel; the dredging and wall stabilizing drill bit stirs the soil into slurry while drilling, and extrudes the soil layer inward and compacts the slurry on the hole wall.

[0005] The hole-forming process described in this invention utilizes a rotary drilling rig to press the outer and inner casings of the pile head into the ground sequentially. While the rotary drilling rig is drilling the pile hole, the dredging and wall-stabilizing drill bit drills downwards. The upper part of the dredging and wall-stabilizing drill bit is a drill cylinder equipped with extrusion strips, and the lower part is an inverted cone shape composed of multiple cutting plates. On the one hand, the cutting plates apply lateral pressure to the soil layer to drill out the hole. On the other hand, the rotary drilling rig uses its huge torque to drive the dredging and wall-stabilizing drill bit to rotate and stir the soil in the hole to form mud. As the dredging and wall-stabilizing drill bit drills, the mud is introduced into the gap between the hole wall and the outer wall of the drill cylinder, and finally pressed onto the surface of the hole wall by the extrusion strips on the outside of the cylinder wall to form a tight and smooth clay slurry film, thereby forming a solidified and firm pile hole in the slurry soil layer. This pile foundation drilling technology for slurry-rich soil strata allows for drilling in these strata without the need for mud pits, slurry preparation, or grouting. Furthermore, it eliminates the need for full casing during drilling, requiring only a short casing to protect the pile head. The drilled pile holes exhibit high density and precision wall protection, resulting in high strength and resistance to collapse or shrinkage. The drilled holes remain stable for extended periods, eliminating the need for immediate concrete pouring. This reduces coordination requirements between different construction teams and minimizes site requirements, allowing for more organized and stable workflow. The drilled pile holes can then be used for subsequent pile drilling, with the concrete pouring team handling the final stages. Simultaneous pouring of concrete into each pile hole improves construction efficiency and reduces costs. Furthermore, the inverted conical bottom not only applies lateral pressure to the soil but also creates an inverted conical structure at the bottom of the hole, concentrating sand, gravel, or other impurities. These impurities are then more easily and thoroughly removed during reverse circulation cleaning. The tight and smooth hole walls, free of concave cavities, effectively reduce or even prevent over-pouring of concrete later. Additionally, the dredging and wall-stabilizing drill bit can convert the added clay into slurry during rotary drilling, eliminating the need for additional slurry preparation equipment and further reducing construction costs and labor.

[0006] Preferably, during the drilling process of the dredging and wall-stabilizing drill bit, hard material fragments are added into the hole.

[0007] Preferably, several flow holes are provided at different horizontal height positions of the drill barrel.

[0008] Preferably, the flow holes at different horizontal heights are arranged alternately.

[0009] Preferably, several extrusion strips are arranged at different heights on the drill barrel along the circumferential direction.

[0010] Preferably, the extrusion strips at adjacent heights are staggered.

[0011] Preferably, the extrusion strip is disposed between two flow holes in the circumferential direction.

[0012] Preferably, the cutting plate is arranged in a spiral bend.

[0013] Preferably, the connecting tube includes a connecting square head at the top and a central shaft connected below the connecting square head, and the central shaft is inverted conical.

[0014] Preferably, the central shaft is an inverted conical prism, and some of the edges at the bottom of the central shaft are provided with inclined surfaces. The cutting plate is mounted on the side of the central shaft behind the edges along the rotation direction, and the concave surface of the arc-shaped cutting plate faces the inclined surface.

[0015] The above-mentioned hole-forming process can further improve the structural strength of pile holes and the construction quality of pile foundations, as well as increase construction efficiency. Attached Figure Description

[0016] Figure 1 This is a structural diagram of the outer and inner casing of the pile head.

[0017] Figure 2 , 3 This is a schematic diagram of the structure of a dredging and wall-stabilizing drill bit.

[0018] Figure 4 This is a side view diagram of the dredging and wall-stabilizing drill bit.

[0019] Figure 5 This is a bottom view structural diagram of a dredging and wall-stabilizing drill bit.

[0020] Figure 6 , 7 This is a schematic diagram of the internal structure of a dredging and wall-stabilizing drill bit. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, top, bottom, inside, outside, vertical, horizontal, longitudinal, counterclockwise, clockwise, circumferential, radial, axial, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0023] If the embodiments of this invention involve descriptions such as "first" or "second," such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] This invention proposes a drilling process for pile foundations in slurry soil strata.

[0025] The hole-forming process for pile foundations in slurry soil strata in this embodiment includes the following steps: A. Installation of the outer casing of the pile head: Press the outer casing of the pile head into the ground; B. Inner casing installation: Press the inner casing into the ground inside the outer casing of the pile head; C. Rotary drilling: A rotary drilling rig drills pile holes without grouting using a dredging and wall-stabilizing drill bit. The dredging and wall-stabilizing drill bit includes a cylindrical drill barrel 1 with openings at both the top and bottom, and a connecting pipe 2 set on the axis of the drill barrel. A support rod 3 is connected between the top of the connecting pipe and the top of the drill barrel. The lower part of the connecting pipe is a central shaft, and the bottom end of the central shaft protrudes from the bottom of the drill barrel. An inclined cutting plate 4 is connected between the bottom end of the central shaft and the bottom of the drill barrel. Several cutting plates are distributed circumferentially and have an inverted conical structure. Several wear-resistant heads 5 are respectively installed on the bottom surface of the central shaft, the bottom edge of the drill barrel, and the drill plate. Several outwardly protruding extrusion strips 7 are installed on the outer wall of the drill barrel. While the dredging and wall-stabilizing drill bit is drilling, it mixes the soil into mud, squeezes the soil layer inward, and compacts the mud onto the hole wall.

[0026] like Figure 1 As shown, a rotary drilling rig is used to press the outer and inner casings of the pile head into the ground sequentially. While the rotary drilling rig is drilling the pile hole, the dredging and wall-stabilizing drill bit drills downwards; as... Figures 2-7 As shown, the upper part of the dredging and wall-stabilizing drill bit is a drill barrel equipped with extrusion strips, and the lower part is an inverted cone shape composed of multiple cutting plates. On the one hand, the cutting plates drill holes by applying lateral pressure to the soil layer. On the other hand, the rotary drilling rig drives the dredging and wall-stabilizing drill bit to rotate and stir the soil in the hole to form mud. As the dredging and wall-stabilizing drill bit drills, the mud is introduced into the gap between the hole wall and the outer wall of the drill barrel. Finally, it is pressed onto the surface of the hole wall by the extrusion strips on the outside of the barrel, forming a tight and smooth clay slurry film, thereby forming a solidified and firm pile hole in the slurry soil layer.

[0027] The aforementioned hole-forming process involves adding a mixture of hard material fragments such as sand, gravel, and a small amount of soil into the hole during the drilling process of the dredging and wall-stabilizing drill bit. The dredging and wall-stabilizing drill bit is used to press these hard material fragments into the hole wall, thereby improving the structural strength of the pile hole.

[0028] The aforementioned dredging and wall-stabilizing drill bit has several flow holes 6 at different horizontal heights of the drill barrel 1. This is because during drilling, soil accumulates inside the drill barrel. When a certain amount of soil accumulates, the rotary drilling rig will move the dredging and wall-stabilizing drill bit out of the hole. Then, by repeatedly rotating the rotary drilling rig in both directions, the soil inside the barrel is thrown out from the bottom of the drill barrel and the flow holes. Drilling continues only after the soil has been cleared. The flow holes 6 at different horizontal heights are staggered to better clean the drill barrel.

[0029] The aforementioned dredging and wall-stabilizing drill bit can have two or more cutting plates installed at the bottom of the drill barrel, depending on the diameter of the pile hole. In this embodiment, the dredging and wall-stabilizing drill bit is equipped with two cutting plates, which can leave a larger through hole at the bottom of the drill barrel. When cleaning the soil inside the drill barrel, the rotary drilling rig repeatedly rotates the dredging and wall-stabilizing drill bit in both forward and reverse directions, and the soil can fall off from the bottom of the drill barrel. If the diameter of the pile hole is large, three, four or more cutting plates can be installed as needed, thereby improving drilling efficiency and making it easier to clean the soil.

[0030] The aforementioned dredging and wall-stabilizing drill bit has several extrusion strips 7 spaced circumferentially at different heights on the drill barrel 1, with the extrusion strips at adjacent heights being staggered. This creates multiple layers and repeated compaction of the borehole wall, which is beneficial for improving construction efficiency and borehole quality. Furthermore, the extrusion strips 7 can be positioned between two circumferential flow holes. This allows for a more compact structure, reducing the size and weight of the drill bit. It also enables the soil ejected from the barrel during drilling to be quickly pressed into the borehole wall, thus better forming a slurry film on the borehole wall and ensuring its compactness and smoothness.

[0031] like Figure 6 , 7As shown, the cutting plate 4 is curved, which makes it easier to dig up the surface soil and facilitates the introduction of the dug soil into the drill barrel. Additionally, the connecting pipe 2 includes a connecting square head 21 at the top and a central shaft 22 connected below the connecting square head. The central shaft is inverted conical, which not only makes it easier for soil to enter the drill barrel but also reduces soil adhesion, making it easier for the rotary drilling rig to shake off the soil. Furthermore, the central shaft 22 is an inverted conical prism, and some edges at the bottom of the central shaft have inclined surfaces 23. The cutting plate 4 is mounted on the side of the central shaft behind these edges along the rotation direction. The concave surface of the curved cutting plate faces the inclined surface, which prevents the corners at the bottom of the central shaft from obstructing the rotation surface of the cutting plate, allowing the cutting plate to more quickly and accurately stir the mud, dig the soil, and introduce it into the drill barrel.

[0032] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A process for forming a hole for a pile foundation in a soil layer, characterized by It comprises the following steps: A. pile head outer casing installation, the pile head outer casing is pressed into the ground; B. inner casing installation, on the inner side of the pile head outer casing, the inner casing is pressed into the ground; C. rotary drilling, rotary drilling machine drills pile hole through dredging solid wall drill bit without grouting, the dredging solid wall drill bit comprises a cylindrical drill cylinder (1) with open upper and lower ends, and a connecting pipe (2) arranged on the axis of the drill cylinder, a support rod (3) is connected between the top of the connecting pipe and the top of the drill cylinder, the lower part of the connecting pipe is a central shaft, the bottom end of the central shaft protrudes from the bottom of the drill cylinder, an inclined cutting plate (4) is connected between the bottom end of the central shaft and the bottom of the drill cylinder, a plurality of cutting plates are distributed circumferentially and have an inverted conical structure; a plurality of wear-resistant heads (5) are respectively arranged on the bottom surface of the central shaft, the bottom edge of the drill cylinder and the drill plate; a plurality of outward protruding extrusion strips (7) are arranged on the outer wall of the drill cylinder; the dredging solid wall drill bit stirs the soil into slurry while drilling, and extrudes the soil layer inward and compacts the slurry on the hole wall.

2. The pore forming process of claim 1, wherein: Hard fragments are added to the hole during the drilling process of the dredging solid wall drill bit.

3. The pore forming process of claim 1, wherein: A plurality of flow-through holes (6) are respectively arranged at different horizontal positions of the drill cylinder (1).

4. The pore forming process of claim 3, wherein: The flow-through holes (6) at different horizontal positions are staggered.

5. The pore forming process according to any one of claims 1 to 4, characterized in that: A plurality of extrusion strips (7) are respectively arranged at different heights on the drill cylinder (1) and are spaced apart circumferentially.

6. The pore forming process of claim 5, wherein: The extrusion strips at adjacent heights are staggered.

7. The pore forming process of claim 5, wherein: The extrusion strips (7) are arranged between two flow-through holes in the circumferential direction.

8. The pore forming process of claim 1, wherein: The cutting plate (4) is arranged in an arc shape.

9. The pore forming process according to claim 1 or 8, characterized in that: The connecting pipe 2 comprises a connecting square head (21) at the top and a central shaft (22) connected below the connecting square head, and the central shaft is inverted conical.

10. The pore forming process of claim 9, wherein: The central shaft (22) is a prismatic inverted cone, and an inclined surface (23) is arranged at part of the edge of the bottom of the central shaft, the cutting plate (4) is arranged on the side surface of the central shaft behind the edge in the rotation direction, and the inner concave surface of the arc-shaped cutting plate faces the inclined surface.

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