Novel root type pile foundation and construction method

Abstract

The invention discloses a novel root type pile foundation and a construction method, the novel root type pile foundation structurally comprises an outer steel pipe pile, an inner steel pipe pile and a root key device, and the outer steel pipe pile and the inner steel pipe pile form a whole through pressure grouting; rectangular holes are uniformly formed in the outer steel pipe pile body at equal intervals; the root key device comprises a seesaw, a root key and a connector, the connector penetrates through the root key, and the connector and the seesaw are welded to form the root key device; root key devices are evenly welded to the inner side of the outer steel pipe pile in the axial direction and the radial direction at equal intervals, the outer steel pipe pile is driven into the designed elevation, the outer steel pipe pile is coaxially and vertically driven into the inner steel pipe pile in the middle, the root keys slide and rotate along the warping plate to gradually penetrate into a pile side soil layer from top to bottom, pressure grouting is conducted between the outer steel pipe pile and the inner steel pipe pile, and root type pile foundation assembly construction is completed. The invention belongs to the technical field of building foundation engineering, provides a novel root type pile foundation and a construction method, can effectively improve the bearing capacity of the foundation, and is convenient to construct, simple in structure and good in economic benefit.

Description

Technical Field

[0001] The present invention belongs to the technical field of building foundation engineering, and particularly relates to a novel root pile foundation and a construction method thereof. Background Art

[0002] With the rapid development of China's economy and the increase in engineering construction projects, the complexity of the projects has increased accordingly. The importance of the foundation in the project has become increasingly prominent, and at the same time, the requirements for the foundation are also getting higher and higher. China has a vast territory and complex terrain. How to make full use of the bearing capacity of the soil mass to effectively drive more soil masses to play a role and economically and effectively improve the bearing capacity of the foundation is the key to current foundation design and construction.

[0003] The root pile is a bionic foundation that can improve the bearing capacity of the pile foundation by jacking precast root keys into the reserved holes in the pile body. Since the root keys mobilize the bearing potential of the soil mass around the foundation, the compressive and uplift bearing capacities of the root pile are higher than those of the ordinary pile foundation, so it has been widely used in engineering construction. At present, the root pile usually adopts the structure form of cast-in-place pile, and the precast root keys are jacked into the surrounding soil layers one by one by using the conventional static pressure pile technology, and then the holes are sealed with special colloid grouting to form the root pile foundation structure. The existing structure and construction method have the following deficiencies: (1) The construction time of the cast-in-place root pile structure is long and the engineering cost is high, and it is difficult to be standardized; (2) The angle of the root key is single and cannot change according to the internal force of the pile, resulting in material waste and high cost; (3) During the construction process, a single root key needs to be pushed forward one by one by machinery, with complex technology and low efficiency; (4) The bonding force between the root key and the soil mass is weak, and the bearing capacity of the surrounding soil mass is not fully mobilized. Therefore, it is urgently needed to develop a novel root pile foundation and a construction method with high bearing capacity, convenient construction, simple structure and good economic benefits. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a novel root pile foundation and a construction method thereof, which can effectively improve the bearing capacity of the foundation, are convenient for construction, have a simple structure and save costs.

[0005] An assembled radical pile foundation, the structure of which includes: an outer steel pipe pile 1, an inner steel pipe pile 2 and a root key device 3. The outer steel pipe pile 1 and the inner steel pipe pile 2 form a whole through pressure grouting 4. The outer steel pipe pile 1 is a steel pipe pile with a circular cross-section, and rectangular holes 1a are evenly arranged at equal intervals along the radial and axial directions of the pile. The inner steel pipe pile 2 is a steel pipe pile with a circular cross-section. The root key device 3 is composed of a rocker 3a, a root key 3b and a U-shaped connector 3c. The rocker 3a is a T-shaped rocker with an arc transition surface. The root key 3b is a claw-shaped root key made of steel. The U-shaped connector 3c is a U-shaped connector made of steel. The connector 3c passes through the root key 3b, and one end of the connector 3c is welded to the arc surface of the rocker 3a to form the root key device 3. The root key device 3 is evenly welded along the axial and radial directions on the inner side of the outer steel pipe pile 1.

[0006] Position and drive the outer steel pipe pile 1 to the designed elevation. Vertically and centrally drive the inner steel pipe pile 2 coaxially inside the outer steel pipe pile 1, so that the root key 3b slides and rotates along the rocker 3a and gradually penetrates into the soil layer on the side of the pile from top to bottom. Carry out pressure grouting 4 between the outer steel pipe pile 1 and the inner steel pipe pile 2 to complete the assembly construction of the radical pile foundation.

[0007] The present invention provides a construction method for an assembled radical pile foundation, which includes the following steps:

[0008] Step 1: According to the actual situation of the project, determine the pile length and pile diameter of the precast outer steel pipe pile, and evenly open rectangular holes along the radial and axial directions of the pile body.

[0009] Step 2: Use steel to make a rocker, a root key and a connector according to the design requirements. There is a round hole in the middle of the root key. Pass the connector through the root key and weld the connector to the rocker to form a root key device.

[0010] Step 3: Overall assembly, evenly weld the root key device along the axial and radial directions on the inner side of the outer steel pipe pile.

[0011] Step 4: Positioning and piling. According to the design requirements, level the site. At the predetermined piling position marked on the ground, use a pile hammer to drive the entire outer steel pipe pile to the designed elevation, then vertically and centrally drive the inner steel pipe pile coaxially. Carry out pressure grouting between the outer steel pipe pile and the inner steel pipe pile to complete the assembly construction of the radical pile foundation.

[0012] Step 5: Repeat the above steps 1, 2, 3, and 4 until all the construction of the radical pile foundation is completed.

[0013] The beneficial effects obtained by the present invention with the above structure are as follows:

[0014] 1. The root keys of this root pile foundation are precast root keys, and the angle between the root keys and the pile axis can be flexibly designed. Compared with the single angle of the existing root foundation, any angle between 0° and 90° can be formed, improving the compressive bearing capacity of the pile foundation and reducing the pile foundation settlement.

[0015] 2. The root keys of this root pile foundation are inserted into the soil around the pile in a rotating manner, causing local disturbance to the soil at the insertion point, which is beneficial for the slurry to flow into the surrounding soil along the root keys under the action of grouting pressure, increasing the stress range of the pile and soil, and improving the uplift bearing capacity of the root pile foundation.

[0016] 3. The construction of this root pile foundation does not require mechanical single - root propulsion of the root keys. All root keys can be constructed in one go, with high construction efficiency, cost savings, and good economic benefits.

[0017] 4. This root pile foundation is an assembled integral structure, which can be fabricated in a standardized, serialized, and finished - product manner, with a high degree of industrialization.

[0018] 5. In the present invention, the pile body is a hollow combination, reducing the pile body mass and lowering the material consumption and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of an assembled root pile foundation related to the present invention;

[0020] Figure 2 is Figure 1 the A - A cross - sectional view of;

[0021] Figure 3 is the elevation view of the outer steel pipe pile 1;

[0022] Figure 4 is the drawing of the root key device;

[0023] Figure 5 is the construction process of the assembled root pile.

[0024] Among them, the outer steel pipe pile 1, the inner steel pipe pile 2, the root key device 3, the rocker 3a, the root key 3b, the connector 3c, and the pressure grouting 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Such as Figures 1-5As shown in the figure, the present invention is a new type of root pile foundation, and its structure includes: an outer steel pipe pile 1, an inner steel pipe pile 2, and a root key device 3. The outer steel pipe pile 1 and the inner steel pipe pile 2 form an integral body through pressure grouting 4; the outer steel pipe pile 1 is a steel pipe pile with an annular cross-section, and rectangular holes 1a are evenly arranged at equal intervals along the radial and axial directions of the pile; the inner steel pipe pile 2 is a steel pipe pile with an annular cross-section; the root key device 3 is composed of a rocker 3a, a root key 3b, and a U-shaped connector 3c. The rocker 3a is a T-shaped rocker with an arc transition surface, the root key 3b is a claw-shaped root key made of steel, and the U-shaped connector 3c is a U-shaped connector made of steel. The connector 3c is passed through the root key 3b, and one end of the connector 3c is welded to the arc surface of the rocker 3a to form the root key device 3; the root key device 3 is evenly welded along the axial and radial directions on the inner side of the outer steel pipe pile 1. The outer steel pipe pile 1 is positioned and driven into the design elevation, and the inner steel pipe pile 2 is vertically and centrally driven into the outer steel pipe pile 1 coaxially, so that the root key 3b slides and rotates along the rocker 3a and gradually pierces into the soil layer on the side of the pile from top to bottom. Pressure grouting 4 is carried out between the outer steel pipe pile 1 and the inner steel pipe pile 2 to complete the assembly construction of the root pile foundation.

[0027] As Figure 2 shown, the outer radius of the inner steel pipe pile is equal to the inner radius of the outer steel pipe pile minus the thickness of the root key device;

[0028] As Figure 3 shown, the width of the rectangular hole is larger than the diameter of the root key;

[0029] The present invention provides a construction method for a new type of root pile foundation, including the following steps:

[0030] Step 1: Determine the pile length and pile diameter of the precast outer steel pipe pile, and evenly open rectangular holes 1a along the radial and axial directions of the pile body;

[0031] Step 2: Use steel to make the rocker 3a, the root key 3b, and the connector 3c. A circular hole is provided in the middle of the root key 3b. The connector 3c is passed through the root key 3b, and the connector 3c is welded to the rocker 3a to form the root key device 3;

[0032] Step 3: Overall assembly;

[0033] Step 4: Positioning and pile driving. Pressure grouting is carried out between the outer steel pipe pile and the inner steel pipe pile to complete the assembly construction of the root pile foundation;

[0034] Step 5: Repeat the above steps 1, 2, 3, and 4 until all the root pile foundation constructions are completed.

[0035] Working principle: (1) The root key device of this root pile foundation is a prefabricated structure. The root key can be designed and manufactured at any angle between 0° and 90° according to the soil layer conditions, solving the problem of the single root key angle in the existing root pile foundation. The variable-angle root key enables the soil to form a greater supporting force on the structure, which can improve the bearing capacity of the pile foundation and reduce the pile foundation settlement. (2) The root key of this root pile foundation penetrates into the soil around the pile in a rotating manner, causing local disturbance to the soil at the insertion point, which is beneficial for the grout to flow into the surrounding soil along the root key under the action of the grouting pressure. After the flowing grout solidifies, it forms a rib stab together with the inserted root key, increasing the stress range of the pile and soil, greatly increasing the range of the soil around the pile that jointly bears force with the root pile, and forming a pile-soil interaction system, which is beneficial for improving the uplift bearing capacity of the root pile foundation. (3) The construction process of the root key of this root pile foundation is as follows: The inner steel pipe pile is concentrically driven downward into the outer steel pipe pile. During the driving process, a sliding friction force is generated between the inner steel pipe pile and the root key, and the sliding friction force causes the root key to slide and rotate along the rocker, so that the root key penetrates into the soil around the pile. During the driving process, all the pile foundation root keys are gradually formed at one time from top to bottom, without single-by-single mechanical jacking one by one, with high construction efficiency and cost savings. (4) This root pile foundation is assembled from an outer steel pipe pile and an inner steel pipe pile and forms an integral structure through grouting. This root pile foundation is an assembled integral structure, which can be manufactured in a standardized, serialized and finished product manner, with a high degree of industrialization. (5) The inside of the pile body of this root pile foundation is hollow, with a small self-weight, achieving the effect of saving materials and good economic benefits.

[0036] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An assembled root pile foundation, comprising an outer steel pipe pile (1), an inner steel pipe pile (2) and a root key device (3), wherein the outer steel pipe pile (1) and the inner steel pipe pile (2) are integrally formed by pressure grouting (4); the root key device (3) comprises a seesaw (3a), a root key (3b) and a connector (3c), wherein the connector (3c) penetrates the root key (3b) and is welded to the seesaw (3a) to form the root key device (3).

2. The assembled root pile foundation according to claim 1, characterized in that: The outer steel pipe pile (1) is a steel pipe pile with an annular cross-section and is provided with rectangular holes (1a) evenly distributed along the radial and axial directions of the pile.

3. The assembled root pile foundation according to claim 1, characterized in that: The inner steel pipe pile (2) is arranged in the form of a steel pipe pile with an annular cross section.

4. The assembled root pile foundation according to claim 1, characterized in that: The seesaw (3a) is a concave rectangular steel plate with an arc transition surface, the root key (3b) is a claw-shaped steel root key, and the connector (3c) is a U-shaped steel connector.

5. The assembled root pile foundation according to claim 1, characterized in that: The inner side of the outer steel pipe pile (1) is welded with root key devices (3) at equal intervals in the axial and radial directions. After the outer steel pipe pile (1) is driven into the soil, the inner steel pipe pile (2) is driven vertically and centrally along the same axis.

6. A method for constructing an assembled root pile foundation according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: According to the actual project situation, determine the pile length and pile diameter of the prefabricated external steel pipe pile, and evenly open rectangular holes (1a) in the radial and axial directions of the pile body; Step 2: according to the design requirements, a seesaw (3a), a root key (3b), and a connector (3c) are made of steel, a round hole is provided in the middle of the root key (3b), the connector (3c) is passed through the root key (3b), and the connector (3c) and the seesaw (3a) are welded to form a root key device (3); Step 3: Assemble the whole, and weld the root key device (3) evenly at equal intervals along the axial direction and radial direction on the inner side of the outer steel pipe pile (1); Step 4: Positioning and piling: According to the design requirements, the site is leveled, and at the predetermined piling position marked on the ground, the entire pile body (1) is driven to the designed elevation with a pile hammer, and the inner steel pipe pile (2) is driven vertically and centrally along the axis, and pressure grouting (4) is performed between the outer steel pipe pile (1) and the inner steel pipe pile (2), thereby completing the root pile foundation assembly construction; Step 5: Repeat the above steps 1, 2, 3, and 4 until all root pile foundation construction is completed.

Images