Pile-type ground reinforcement method and pile-type ground reinforcement structure

Abstract

To provide a pile-type ground reinforcement method and pile-type ground reinforcement structure that can obtain sufficient bearing performance by the bearing force of the piles alone even if the bearing capacity of the ground below a base of a foundation decreases, while taking advantage of the economic efficiency of being able to construct in a short construction period by using inexpensive thin-diameter steel pipes.SOLUTION: A steel pipe that will become a core pile 1 is pressed into the ground to a specified depth without excavating or stirring the ground. An injection pipe consisting of a small-diameter hollow tube is inserted into the core pile 1, and solidification material is pumped into the injection pipe and discharged into the ground to form a base protection section 5 impregnated with the solidification material around a lower end of the core pile. While the solidification material is hardening, a steel pipe that will become a support pile 6 is pressed into the core pile close to it, and its lower end is fixed in the base protection section 5. Multiple support piles 6 are buried around the core pile 1, and the lower ends of the core pile 1 and the multiple support piles 6 are joined together around the base protection section 5 to form a composite pile unit 8, and a building foundation 9 is placed on top of the composite pile unit 8.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present application relates to a pile-type ground reinforcing method and a pile-type ground reinforcing structure in which straight pipes such as thin-diameter steel pipes are buried to increase the bearing capacity of the ground. [Background technology]

[0002] When sufficient bearing capacity of the ground is not obtained during construction of a building, various types of pile foundation methods and ground improvement methods are adopted as a means of reinforcing the bearing capacity. Among them, a method of pressing (penetrating) a general-purpose thin steel pipe called a "single pipe" or "single pipe pipe" into the ground to form a support pile is known as a ground improvement method particularly applicable to relatively small buildings such as detached houses, solar power generation facilities, and other simple outdoor structures (e.g., Patent Document 1). This type of ground improvement method is implemented based on the concept of a "piled raft method" in which the load of the building is supported not only by the piles, but by adding the bearing capacity of the ground below the bottom of the spread foundation (mat foundation) and the bearing capacity of the piles to support the building.

[0003] The "RES-P method" disclosed in Non-Patent Documents 1 and 2, etc., and the "Super Narrow Method" disclosed in Non-Patent Document 3 are also considered to be methods similar to the above-mentioned ground improvement method.

[0004] These ground improvement methods do not require large-scale excavation or mixing of the ground, so they have the advantages of being low cost, low noise, short construction time, and no waste soil. In addition, they can be carried out using small heavy machinery, making them particularly suitable for construction in small areas. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP-A-58-146616 (Taisei Corporation) [Non-patent literature]

[0006] [Non-Patent Document 1] Something Co., Ltd., “RES-P Construction Method”, [online] Internet, retrieved on July 5, 2023<URL:https: / / www.s-thing.co.jp / jiban_kairyo / kairyo_koho / res_p / > [Non-Patent Document 2] Design Office Soil, “RES-P Construction Method”, [online] Internet, retrieved on July 5, 2023<URL:https: / / www.soil-design.co.jp / resp.html> [Non-Patent Document 3] Grantec Co., Ltd., "Super Narrow Method", [online] Internet, retrieved on July 5, 2023<URL:https: / / www.grountec.net / business / screw_press / 02_super_narrow / > Summary of the Invention [Problem to be solved by the invention]

[0007] In the piled raft method mentioned above, if the bearing capacity of the ground below the base of the spread foundation decreases due to liquefaction of the ground, there is a risk that the bearing capacity of the piles alone will not be able to ensure the bearing capacity as originally designed. However, even if you try to ensure sufficient bearing capacity with piles alone, in a method that uses thin steel pipes such as single pipes for the piles, it is difficult to obtain a large friction force between each pile and the ground, so it is necessary to drive a large number of piles into a certain area, which is uneconomical.

[0008] The invention disclosed in this application was conceived as an alternative construction method to such conventional technology, and proposes a pile-type ground reinforcement construction method and a pile-type ground reinforcement structure using said construction method, which are capable of obtaining sufficient bearing performance based on the bearing capacity of the piles alone, while taking advantage of the economical efficiency of being able to carry out construction in a short period of time by using inexpensive thin-diameter steel pipes, etc. [Means for solving the problem]

[0009] The invention of the pile-type ground reinforcement method adopted in the present application to achieve the above-mentioned object is characterized as including the following [Step 1] to [Step 5]. [Step 1] A straight pipe with its lower end sealed with a protective cap is pressed into the ground to a specified depth without excavating or stirring the ground to form a core pile. [Step 2] An injection tube consisting of a hollow tube with a smaller diameter than the core pile is inserted inside the core pile, the protective cap is crushed or removed at the lower end of the injection tube to cause the lower end of the injection tube to protrude from the lower end of the core pile, and the solidification material pressurized into the injection tube is ejected from the lower end of the injection tube into the ground, forming a root protection portion impregnated with the solidification material around the lower end, and then the injection pipe is removed from the core pile. [Step 3] While the solidification material is solidifying, a straight pipe separate from the core pile is pressed in parallel to the core pile, and its lower end is fixed within the foot protection section to serve as a support pile dependent on the core pile. [Step 4] By burying one or more support piles around the core pile, a composite pile unit is formed in which the lower ends of the core pile and the support pile are integrally connected by rotating the base protection section. [Step 5] Providing a building foundation on at least one set of the composite pile units to support the building load.

[0010] Furthermore, in the above [Step 2], when the solidification material is discharged into the ground through the injection pipe, the injection pipe is raised and lowered to move the lower end of the injection pipe up and down while discharging the solidification material.

[0011] Furthermore, in the above [Step 1] and [Steps 3] to [Step 4], the change in the compressive reaction force is measured when the core pile and / or the support pile is pressed in, thereby grasping the resistance force of the ground acting on the core pile and / or the support pile, and determining whether the burial depth of the core pile and / or the support pile is appropriate.

[0012] In addition, the invention of the pile-shaped ground reinforcement structure adopted in the present application is characterized as comprising at least one set of composite pile units consisting of a core pile made of a straight pipe buried to a predetermined depth in the ground, a base protection section formed by impregnating a solidifying material around the lower end of the core pile, and one or more support piles made of straight pipes separate from the core pile and buried in close proximity to the core pile so as to fix their lower ends in the base protection section, and a building foundation is placed on the composite pile unit, and the load of the building is supported by the composite pile unit.

[0013] In this pile-shaped ground reinforcement structure, the straight pipe constituting the core pile and / or the straight pipe constituting the support pile can each be a single pipe.

[0014] Furthermore, in this pile-like ground reinforcement structure, it is more preferable that the multiple support piles are arranged in a regular polygonal shape or a ring shape with the central pile as the centroid in a plan view.

[0015] Furthermore, it is more preferable that the lower end of the support pile is buried deeper than the lower end of the core pile, since the support pile is integrated with the core pile via the foot protection portion. Effect of the Invention

[0016] The pile-shaped ground reinforcement method configured as described above is composed of a process of pressing multiple straight pipes that serve as core piles and support piles into the ground without excavating or stirring the ground, and a process of injecting a solidification material into the ground from an injection pipe inserted inside the core pile, and can be constructed efficiently in a short period of time since it does not require large-scale heavy machinery and does not require storage or backfilling of excavated soil. In addition, it is economical because thin-diameter steel pipes such as single pipes can be suitably used for the core piles and support piles, and construction can be performed with small heavy machinery even on a small site.

[0017] In the pile-type ground reinforcement structure constructed by this pile-type ground reinforcement method, a composite pile unit is formed in which the core pile and the multiple supporting piles surrounding it are integrated through the base reinforcement section, and the composite pile unit exerts a bearing capacity equivalent to that of a thick-diameter pile. Therefore, the composite pile unit alone can maintain sufficient bearing capacity without relying on the bearing capacity of the ground below the base of the foundation. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is an explanatory diagram showing an overview of [Step 1] (core pile embedding step) of the pile-type ground reinforcement method disclosed in the present application. [Diagram 2] FIG. 2 is an explanatory diagram showing an overview of [Step 2] (step of forming the foot fixing portion) of the pile-type ground reinforcement method. [Diagram 3] FIG. 2 is an explanatory diagram showing an overview of [Step 3] (the step of burying the auxiliary piles) of the pile-type ground reinforcement method. [Figure 4] FIG. 2 is an explanatory diagram showing an overview of [Step 4] (integration step of the core pile and the support pile) of the pile-type ground reinforcement method. [Diagram 5] FIG. 2 is an explanatory diagram showing [Step 5] (building foundation construction step) of the pile-shaped ground reinforcement method and an overview of the pile-shaped ground reinforcement structure disclosed in the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 1 to 5 are explanatory diagrams showing steps of a pile-like ground reinforcing method according to one embodiment of the invention disclosed in the present application. Hereinafter, this pile-like ground reinforcing method and the pile-like ground reinforcing structure obtained thereby will be described in the order of steps.

[0020] In this pile-shaped ground reinforcement method and pile-shaped ground reinforcement structure, a hollow circular cross-section thin steel pipe is used as the pile material. The specifications of steel pipes used for scaffolding, supports, foundation piles, etc. in architectural and civil engineering works are stipulated in the Japanese Industrial Standards (JIS) G3444:2015 "General structural carbon steel pipes", but the "thin diameter" in the invention disclosed in this application is set to an outer diameter of less than 100 mm (effectively 89.1 mm or less), and a more preferable range of outer diameter is set to 42.7 mm to 76.3 mm. Among them, a hot-dip galvanized steel pipe with an outer diameter of 48.6 mm and a wall thickness of 1.8 mm to 3.5 mm, called a "single pipe", is particularly practical in terms of material strength, economy, ease of handling, etc. The embodiment described below is also assumed to use this single pipe. However, in the invention disclosed in this application, instead of the steel pipes described above, it is also possible to use other metal pipes, or high-rigidity resin pipes made of fiber reinforced plastic (FRP), carbon fiber reinforced plastic (CFRP), etc. In this specification and claims, they are collectively referred to as "straight pipes."

[0021] [Step 1] (Core pile installation step) First, as shown in FIG. 1, heavy equipment W is installed on the construction surface G where the foundation of the building is to be installed, and a steel pipe to be the "core pile 1" is buried in the ground. If the outer diameter is about the same as that of a single pipe, construction can be easily performed using a small pile driver or boring test machine. However, the invention disclosed in this application does not particularly limit the type of heavy equipment W. In order to maintain the peripheral friction force against the ground, this core pile 1 does not excavate or stir the ground beyond the outer diameter of the core pile 1, and is pressed into the vertical direction basically without rotation (with some rotation if the ground is hard). At this time, in order to prevent soil from entering the inside of the core pile 1, a pointed protective cap 2 is inserted into the lower end of the core pile 1 to temporarily secure it.

[0022] The depth to which the core pile 1 is buried is determined by the condition of the ground, but if the length of the prepared steel pipe does not reach that depth, the steel pipe is buried to the specified depth while being extended as appropriate using joint members (not shown) etc. When burying the core pile 1, it is preferable to determine not only the burial depth but also the numerical changes in the pressing reaction force, rotational torque, embedment speed, etc. using a measuring device (not shown) etc. attached to the heavy equipment W to grasp the resistance force of the ground acting on the core pile 1 (distribution of ground strength according to depth) and to determine how much bearing capacity the core pile 1 is able to exert, whether the burial depth of the core pile 1 is sufficient, etc.

[0023] When the lower end of the core pile 1 reaches a prescribed depth, the heavy equipment W is removed from the core pile 1 with the upper end of the core pile 1 protruding several centimeters to several tens of centimeters above the construction surface. When using heavy equipment that can hold the middle part of the steel pipe without blocking the upper end opening of the steel pipe, such as that disclosed in the above-mentioned Non-Patent Document 3, the next step [Step 2] may be carried out with the heavy equipment still installed on the core pile 1.

[0024] [Step 2] (Root reinforcement formation step) As shown in FIG. 2, an injection pipe 3, which is a hollow pipe with a diameter smaller than the inner diameter of the core pile 1 and longer than the overall length of the core pile 1, is inserted from above ground into the buried core pile 1, and the protective cap 2, which is temporarily fixed to the core pile 1, is broken or pushed downward by the lower end of the injection pipe 3, so that the lower end of the injection pipe 3 protrudes from the lower end of the core pile 1. A solidification material supply device 4, which is composed of a mixer, a tank, a pump, a power source, etc., is connected to the upper end of the injection pipe 3, and a solidification material such as cement milk is pressure-fed from the supply device 4 into the injection pipe 3. A discharge port 31 of an appropriate shape that can discharge the solidification material to the side and downward is formed at the lower end of the injection pipe 3. By discharging the solidification material from the discharge port 31 into the ground at high pressure, a bulb-shaped root fixing portion 5 impregnated with the solidification material is formed around the lower end of the injection pipe 3. In addition to cement milk, various known liquid solidification materials suitable for soil can be selected as the solidification material.

[0025] If the position of the discharge port 31 is fixed and the soil of the ground is homogeneous, the base fixing portion 5 is considered to be formed into a substantially hemispherical shape expanding downward. If possible, when discharging the solidification material, the injection pipe 3 is raised and lowered to raise and lower the height of the discharge port 31, thereby expanding the base fixing portion 5 in the height direction and forming a substantially spherical or cylindrical shape. The injection pipe 3 may be raised by utilizing the reaction of the pressure of discharging the solidification material. At this time, the core pile 1 may be raised and lowered in accordance with or in opposition to the raising and lowering of the injection pipe 3 to increase the height of the base fixing portion 5.

[0026] Then, once a foot protection portion 5 of a preferred size, described below, has been formed, the injection pipe 3 is removed from the core pile 1. There is no problem with the solidification material remaining inside the lower end of the core pile 1 after the injection pipe 3 has been removed. The foot protection portion 5 thus formed around the lower end of the core pile 1 becomes one with the core pile 1, greatly increasing the bearing capacity of the core pile 1.

[0027] [Step 3] (Pile installation step) Next, as shown in FIG. 3, heavy machinery W is again installed near the core pile 1, and a steel pipe separate from the core pile 1 is pressed in parallel to and close to the core pile 1 while the solidification material impregnated in the ground is waiting to solidify. This steel pipe becomes the "support pile 6" that is subordinate to the core pile 1. "Subordinate to the core pile 1" means that it corresponds to the core pile 1 that was buried earlier and works together with the core pile 1. The same single pipe as the core pile 1 can be suitably used for this support pile 6, but steel pipes of different diameters and straight pipes made of other materials can also be used. When single pipes are used for the core pile 1 and the support pile 6, the guideline for "close to the core pile 1" is approximately 0 cm (where the core pile 1 and the support pile 6 come into contact with each other) to 50 cm.

[0028] The support pile 6 is buried to a depth where its lower end is fixed in the foot fixing section 5. By burying the lower end of the support pile 6 to a position deeper than the lower end of the core pile 1, it is possible to ensure that it is fixed in the foot fixing section 5. It is acceptable for the lower end of the support pile 6 to pass through the foot fixing section 5 and protrude below the foot fixing section 5. A protective cap may or may not be attached to the lower end of the support pile 6.

[0029] At least one support pile 6, preferably multiple support piles 6, are buried around one core pile 1 so as to surround the core pile 1. The number of support piles 6 is set according to the condition of the ground, the magnitude of the load to be supported, and the like. If multiple support piles 6 are used, it becomes easier to balance the bearing force with the core pile 1 at the center. When there are two support piles 6, they are arranged symmetrically around the core pile 1, and when there are three or more support piles 6, they are arranged in a regular polygonal shape or a ring shape with the core pile 1 as the centroid in a plan view. In practical terms, it is preferable to arrange four support piles 6 in a square shape around the core pile 1, or six support piles 6 in a regular hexagonal shape, in terms of balance. The number of support piles 6 subordinate to each of the multiple core piles 1 may be different. It is more preferable to form the maximum diameter of the base fixing portion 5 to be about twice or more the area (outer diameter) surrounded by the multiple support piles 6, since this improves the fixation of all support piles 6 to the base fixing portion 5.

[0030] When the support pile 6 is buried, it is preferable to measure the pressing reaction force, rotation torque, embedment speed, etc. using a measuring device or the like provided on the heavy machine W, and compare the measured values ​​with the measured values ​​when the core pile 1 is buried to grasp the changes in the pressing reaction force and rotation torque acting on the support pile 6 during the burial process, and to judge whether the lower end of the support pile 6 has reached the base fixing part 5, how much bearing force it is capable of exerting, etc. When the lower end of the support pile 6 reaches the base fixing part 5, the support pile 6 may be pulled out a little, and the reaction force (resistance force) and the amount of displacement at that time may be confirmed. The bearing force of this pile-shaped ground reinforcement method depends on whether the core pile 1 and the support pile 6 are reliably integrated through the base fixing part 5, so that the quality of construction can be suitably guaranteed by following such measurement and judgment procedures.

[0031] [Step 4] (Integration of the core pile and the support pile) Through these steps, a set of "composite pile units 8" is formed in which one core pile 1 and one or more support piles 6 are integrated by rotating the base fixing section 5. The core pile 1 and the support piles 6 each exert a peripheral friction force with the ground, so the bearing capacity increases by the number of support piles 6. When the base fixing section 5 hardens and the lower ends of the core pile 1 and the support piles 6 surrounding it are joined together, the core pile 1 and the support piles 6 surrounding it respond in a cantilever manner to the deformation of the ground, exerting a bearing capacity comparable to that of a thick-diameter steel pipe pile or a concrete pile.

[0032] Furthermore, as shown in Figure 4, if the heights of the heads of the core pile 1 and the support pile 6 are cut to the same height and their heads are covered with a lid-like body 7 made of a rigid material such as steel or precast concrete, and the heads of the core pile 1 and the support pile 6 are also joined together as a single unit, the rigidity and supporting capacity of the composite pile unit 8 will be further increased.

[0033] [Step 5] (Building foundation construction process) Once the necessary number of composite pile units 8 are formed within the area where the building is to be constructed, the foundation 9 of the building is laid on top of the composite pile units 8, as shown in FIG. 5. The foundation 9 can be of any structure or construction method as long as it can transfer the load to the composite pile units 8 rationally. In this way, a pile-shaped ground reinforcement structure can be obtained in which the load of the building applied to the foundation 9 is supported by the composite pile units 8. In this pile-shaped ground reinforcement structure, the core pile 1 and one or more supporting piles 6 surrounding it are integrally connected at their lower and upper ends, so that if the foot reinforcement part 5 is properly formed, the piles alone can provide sufficient support without relying on the bearing capacity of the ground below the base of the foundation. If many composite pile units 8 are installed over a wide area, it can be applied to large-scale buildings.

[0034] A reasonable procedure for forming multiple sets of composite pile units 8 is to first repeat [Step 1] for the number of sets to bury multiple core piles 1 in their designated positions, and then carry out [Steps 2] to [Steps 4] for each core pile 1. It is also possible to carry out [Steps 1] to [Steps 4] for each core pile 1, and repeat this process for each core pile 1. In any case, the division between each step is not strict, and they may be carried out in parallel as appropriate, or slightly earlier or later depending on the construction site.

[0035] This pile-shaped ground reinforcement structure can be constructed as simply and efficiently as the conventional ground improvement method using a single pipe, using a small diameter steel pipe such as a single pipe that is inexpensive and easy to handle, and a small heavy machine that can be brought into a narrow site. It also has the same advantages as the conventional method, such as low noise, short construction period, and no need to store and backfill the excavated soil. [Step 2], in which a solidification material is discharged around the lower end of the core pile 1 to form a foot hardening part 5, is added to the conventional ground improvement method, and the solidification material supply device 4 that must be prepared for this purpose can also be configured compactly, for example, by loading a mixer, tank, pump, power source, etc. onto a Unic vehicle.

[0036] The above describes the embodiments of the pile-shaped ground reinforcement method and the pile-shaped ground reinforcement structure disclosed in the present application, but the technical scope of the present invention should not be interpreted as being limited by the illustrated embodiments, but should be interpreted conceptually based on the claims. The names of the components used in the claims and the specification are for convenience in order to make the invention easier to understand specifically, and the names do not limit the concept or properties of the components more than necessary. When implementing the invention disclosed in the present application, the detailed shape, dimensions, structure, material, quantity, connection form with other elements, relative positional relationship, etc. of the components not specifically specified in the claims can be appropriately modified within a range in which the effects are substantially equal to or greater than those of the illustrated embodiments.

[0037] Furthermore, the embodiments and other matters disclosed in this specification can also be understood as the technical ideas described in the following supplementary notes.

[0038] (Appendix 1) A pile-type ground reinforcement method including the steps 1 to 5 below. [Step 1] A straight pipe with its lower end sealed with a protective cap is pressed into the ground to a specified depth without excavating or stirring the ground to form a core pile. [Step 2] An injection tube consisting of a hollow tube with a smaller diameter than the core pile is inserted inside the core pile, the protective cap is crushed or removed at the lower end of the injection tube to cause the lower end of the injection tube to protrude from the lower end of the core pile, and the solidification material pressurized into the injection tube is ejected from the lower end of the injection tube into the ground, forming a root protection portion impregnated with the solidification material around the lower end, and then the injection pipe is removed from the core pile. [Step 3] While the solidification material is solidifying, a straight pipe separate from the core pile is pressed in parallel to the core pile, and its lower end is fixed within the foot protection section to serve as a support pile dependent on the core pile. [Step 4] By burying one or more support piles around the core pile, a composite pile unit is formed in which the lower ends of the core pile and the support pile are integrally connected by rotating the base protection section. [Step 5] Providing a building foundation on at least one set of the composite pile units to support the building load. (Appendix 2) In step 2 of the pile-type ground reinforcement method described in Appendix 1, When discharging the solidification material into the ground through the injection pipe, the core pile and the injection pipe are raised and lowered to move the lower end of the injection pipe up and down while discharging the solidification material. A pile-type ground reinforcement method characterized by the above. (Appendix 2-2) Following [Step 4] in the pile-type ground reinforcement method described in Appendix 1 or Appendix 2, The heights of the heads of the core pile and the multiple support piles are aligned, and a rigid lid-like body is placed on the heads to integrally connect the heads of the core pile and the support piles, and then A foundation for a building is provided on the lid-like body. A pile-type ground reinforcement method characterized by the above. (Appendix 3) In the pile-type ground reinforcement method described in Appendix 1, Appendix 2 or Appendix 3, in [Step 1] and [Step 3] to [Step 4], By measuring the change in the pressing reaction force when the core pile and / or the support pile are pressed in, the resistance force of the ground acting on the core pile and / or the support pile is grasped, and the appropriateness of the embedment depth of the core pile and / or the support pile is judged. A pile-type ground reinforcement method characterized by the above. (Appendix 4) A core pile consisting of a straight pipe buried to a predetermined depth in the ground; A base fixing portion formed by impregnating a solidification material around the lower end of the core pile; One or more auxiliary piles made of straight pipes separate from the core pile, which are buried in the base fixing portion so as to fix their lower ends in the vicinity of the core pile; At least one composite pile unit is formed by connecting the A building foundation is provided on the composite pile units, and the load of the building is supported by the composite pile units. A pile-shaped ground reinforcement structure. (Appendix 5) In the pile-type ground reinforcement structure described in Appendix 4, The straight pipe constituting the core pile is a single pipe. A pile-shaped ground reinforcement structure. (Appendix 6) In the pile-type ground reinforcement structure described in Appendix 4 or Appendix 5, The straight pipe constituting the splice is a single pipe. A pile-shaped ground reinforcement structure. (Appendix 7) In the pile-type ground reinforcement structure described in Appendix 4, The plurality of support piles are arranged in a regular polygonal shape or a ring shape with the central pile as a centroid in a plan view. A pile-shaped ground reinforcement structure. (Appendix 8) In the pile-shaped ground reinforcement structure according to any one of Supplementary Note 5 to Supplementary Note 8, The lower ends of all of the plurality of support piles are buried deeper than the lower end of the core pile. A pile-shaped ground reinforcement structure. (Appendix 9) In the pile-shaped ground reinforcement structure according to any one of Supplementary Note 4 to Supplementary Note 8, The height of the heads of the core pile and the multiple supporting piles surrounding it are aligned, The heads are integrally connected to each other by a lid-like body made of a rigid body, The foundation of the building was provided on the lid-like body. A pile-shaped ground reinforcement structure. [Industrial Applicability]

[0039] The invention disclosed in this application can be widely used as a technique for reinforcing the ground during construction work of small to medium-sized buildings and the like. [Explanation of symbols]

[0040] 1 heart pile 2 Protective cap 3 Injection tube 31 Discharge port 4 Feeding device 5 Root protection section 6 Support pile 7 Occipital body 8 Composite pile unit 9 Basics G Construction side W Heavy Machinery

Claims

1. A pile-type ground reinforcement method including the following [Step 1] to [Step 5]. [Step 1] A straight pipe with its lower end sealed with a protective cap is pressed into the ground to a specified depth without excavating or stirring the ground to form a core pile. [Step 2] An injection tube consisting of a hollow tube with a smaller diameter than the core pile is inserted inside the core pile, the protective cap is crushed or removed at the lower end of the injection tube to cause the lower end of the injection tube to protrude from the lower end of the core pile, and the solidification material pressurized into the injection tube is ejected from the lower end of the injection tube into the ground, forming a root protection portion impregnated with the solidification material around the lower end, and then the injection pipe is removed from the core pile. [Step 3] While the solidification material is solidifying, a straight pipe separate from the core pile is pressed in parallel to the core pile, and its lower end is fixed within the foot protection section to serve as a support pile dependent on the core pile. [Step 4] By burying one or more support piles around the core pile, a composite pile unit is formed in which the lower ends of the core pile and the support pile are integrally connected by rotating the base protection section. [Step 5] Providing a building foundation on at least one set of the composite pile units to support the building load.

2. In the pile-shaped ground reinforcement method according to claim 1, in [Step 2], When discharging the solidification material into the ground through the injection pipe, the injection pipe is raised and lowered to move the lower end of the injection pipe up and down while discharging the solidification material. A pile-type ground reinforcement method characterized by the above.

3. In the pile-shaped ground reinforcement method according to claim 1, in [Step 1] and [Step 3] to [Step 4], By measuring the change in the pressing reaction force when the core pile and / or the support pile are pressed in, the resistance force of the ground acting on the core pile and / or the support pile is grasped, and the appropriateness of the embedment depth of the core pile and / or the support pile is judged. A pile-type ground reinforcement method characterized by the above.

4. A core pile consisting of a straight pipe buried to a predetermined depth in the ground; A base fixing portion formed by impregnating a solidification material around the lower end of the core pile; One or more auxiliary piles made of straight pipes separate from the core pile, which are buried in the base fixing portion so as to fix their lower ends in the vicinity of the core pile; At least one composite pile unit is formed by connecting the A building foundation is provided on the composite pile units, and the load of the building is supported by the composite pile units. A pile-shaped ground reinforcement structure.

5. The pile-shaped ground reinforcement structure according to claim 4, The straight pipe constituting the core pile is a single pipe. A pile-shaped ground reinforcement structure.

6. The pile-shaped ground reinforcement structure according to claim 4 or 5, The straight pipe constituting the splice is a single pipe. A pile-shaped ground reinforcement structure.

7. The pile-shaped ground reinforcement structure according to claim 4, The plurality of support piles are arranged in a regular polygonal shape or a ring shape with the central pile as a centroid in a plan view. A pile-shaped ground reinforcement structure.

8. The pile-shaped ground reinforcement structure according to claim 4, The lower end of the support pile is buried deeper than the lower end of the core pile. A pile-shaped ground reinforcement structure.

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