Fabricated short pile-spiral anchor composite foundation and construction process thereof

Abstract

The invention relates to the technical field of power construction, in particular to an assembly type short pile-spiral anchor composite foundation and a construction technology thereof.The assembly type short pile-spiral anchor composite foundation comprises an anchor rod, a first spiral anchor disc is arranged on the lower section of the anchor rod, a flange plate is arranged at the top end of the anchor rod, and a steel cylinder is arranged on the anchor rod and located between the flange plate and the uppermost first spiral anchor disc; the anchor rod penetrates through the steel cylinder from top to bottom and is coaxial with the central axis of the steel cylinder; the spiral anchor has the advantages that the problem that the horizontal bearing capacity of the spiral anchor is insufficient can be solved under the condition that the advantages that the spiral anchor is convenient and rapid to construct, low in manufacturing cost and capable of rapidly generating the bearing capacity after a pile is formed are kept.

Description

Technical Field

[0001] The invention relates to the technical field of electric power construction, and in particular to an assembled short pile-screw anchor composite foundation and a construction process thereof. Background Art

[0002] Transmission lines are carriers of electric energy transmission in power systems. In the construction of transmission lines, transmission towers are important structural structures and are widely used in overhead transmission lines of various voltage levels. Under the action of wind loads, conductor loads, tower deadweight loads, etc., the foundation of the transmission tower must bear vertical and horizontal composite loads. For special corner towers, terminal towers, etc., the horizontal load is even greater. According to the load data of the State Grid 220kV general design tower type undertaken by Zhejiang Institute in recent years, the horizontal pull-out load ratio is between 0.14 and 0.24.

[0003] At present, the main types of transmission tower foundations include extended foundation, excavation foundation, equipment foundation, spiral anchor foundation, etc. Among them, the spiral anchor foundation has been widely promoted and applied by the State Grid in recent years because of its advantages such as convenient and fast construction, low cost, and rapid bearing capacity after pile formation. The traditional spiral anchor foundation consists of an anchor head, a spiral anchor plate and an anchor rod. By connecting the top of the anchor rod with a special torque drive head, the spiral anchor can be screwed into the soil like a screw. The anchor plate can provide a large anchoring force and downward pressure resistance. The horizontal force is mainly borne by the anchor rod. However, due to factors such as construction equipment, cost, and production process, the diameter of the anchor rod is often small (within 630mm), and the horizontal bearing capacity provided is limited.

[0004] In order to overcome the problem of insufficient horizontal bearing capacity of spiral anchors, the current common practice is to cast a concrete cap on the top of the spiral anchor, but this will reduce the advantages of spiral anchors such as convenient and quick construction and immediate bearing capacity after pile formation, and the excavation of the cap will have an adverse impact on the surrounding environment. Another method is to use more than 3 straight anchors and inclined anchors to form a spiral anchor group, use the anchor group foundation to provide horizontal resistance, and use a steel cap to connect the spiral anchor. However, the disadvantage of this method is that it will reduce the low cost advantage of the spiral anchor. On the other hand, the steel cap construction requires high precision, which reduces the advantage of convenient construction of the spiral anchor.

[0005] Based on this, this case is brought forward. Summary of the invention

[0006] One of the purposes of the present invention is to provide an assembled short pile-helical anchor composite foundation to solve the problem of insufficient horizontal bearing capacity of the helical anchor, while maintaining the advantages of convenient and fast construction of the helical anchor and rapid generation of bearing capacity after pile formation.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A fabricated short pile-helical anchor composite foundation comprises an anchor rod, a plurality of spiral anchor plates are arranged at the lower section of the anchor rod, a flange is arranged at the top of the anchor rod, a steel cylinder is arranged on the anchor rod, the steel cylinder is located between the flange and the uppermost spiral anchor plate, and the anchor rod penetrates the steel cylinder from top to bottom and is coaxial with the central axis of the steel cylinder.

[0009] Furthermore, the first form of the steel cylinder is a hollow and closed structure, and the bottom surface of the steel cylinder is a spiral anchor plate 2 with a diameter larger than the outer diameter of the cylinder body.

[0010] Furthermore, the second form of the steel cylinder is a hollow structure with openings at both ends, and the space between the inner wall of the steel cylinder and the anchor rod is filled with concrete.

[0011] The second object of the present invention is to provide a construction process for a fully assembled short pile-spiral anchor composite foundation for the above-mentioned hollow and closed steel barrel, comprising the following steps: the anchor rods are welded and fixed to the top and bottom surfaces of the steel barrel respectively, without the need for excavation and concrete pouring, and the steel barrel is screwed into the foundation together with the anchor rods.

[0012] The third object of the present invention is to provide a construction process for the above-mentioned assembled short pile-screw anchor composite foundation with both ends open and hollow steel barrel, comprising the following steps:

[0013] Place the steel cylinder on the foundation surface;

[0014] Use a large diameter spiral drill bit to drill a hole downward in the steel cylinder;

[0015] Press the steel cylinder down into the foundation;

[0016] Clean the debris in the hole;

[0017] Drill the screw anchor foundation into the hole;

[0018] Concrete is poured or precast concrete blocks are placed, and the precast concrete blocks are fixedly connected to each other and to the anchor rods.

[0019] The advantages of the present invention are: an assembled steel cylinder short pile is arranged on the upper part of the assembled short pile-helical anchor composite foundation, and a steel spiral anchor foundation is arranged on the lower part. The foundation combines the respective advantages of the spiral anchor and the short pile foundation. The upper steel cylinder short pile bears most of the horizontal load, which makes up for the disadvantage of poor horizontal bearing capacity of the traditional spiral anchor foundation. The lower spiral anchor bears most of the vertical load, which greatly enhances the overall force of the foundation. At the same time, the construction accuracy of a single spiral anchor is also easier to control, reducing the construction difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the fully assembled short pile-spiral composite anchor foundation in Example 1;

[0021] Figure 2 This is a schematic diagram of the assembled short pile-spiral composite anchor foundation in Example 2;

[0022] Description of symbols

[0023] 1. Anchor rod; 2. Flange; 3. Spiral anchor plate 1; 4. Spiral anchor plate 2; 5. Steel cylinder; 6. Precast concrete block. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the embodiments. It should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside" and "outside" herein are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0025] Example 1

[0026] like Figure 1 As shown, this embodiment proposes a fully assembled short pile-screw anchor composite foundation, including an anchor rod 1, a plurality of screw anchor plates 3 are arranged at the lower section of the anchor rod 1, and a flange 2 is arranged at the top of the anchor rod 1. A steel cylinder 5 is arranged on the anchor rod 1, and the steel cylinder 5 is located between the flange 2 and the uppermost screw anchor plate 3. The anchor rod 1 penetrates the steel cylinder 5 from top to bottom and is coaxial with the central axis of the steel cylinder 5. The steel cylinder 5 is a hollow and closed structure, and the bottom surface of the steel cylinder 5 is a screw anchor plate 4 whose diameter is larger than the outer diameter of the cylinder body.

[0027] The composite foundation is suitable for situations where the load is not large and the size of the composite foundation is small. It can be designed and constructed in a fully assembled manner. The steps are as follows:

[0028] A spiral anchor plate 24 with a larger diameter is welded on the upper part of the anchor rod 1, and a steel cylindrical short pile with an upper sealed end is welded on the upper part of the spiral anchor plate 24; during construction, since the soil on the upper part of the foundation is relatively soft, the steel cylindrical short pile can be drilled into the soil together with the spiral anchor plate 24, without the need for excavation and concrete pouring, the construction speed is fast, the efficiency is high, and the environmental protection effect is good.

[0029] The following table is a data comparison of the fully assembled short pile-spiral anchor composite foundation with cast-in-place piles and cap spiral anchors. From the data, we can see that the fully assembled short pile-spiral anchor composite foundation has the advantages of small size, less consumables and convenient construction.

[0030]

[0031] Example 2

[0032] like Figure 2As shown, this embodiment proposes an assembled short pile-screw anchor composite foundation, including an anchor rod 1, a plurality of screw anchor plates 3 are arranged at the lower section of the anchor rod 1, and a flange 2 is arranged at the top of the anchor rod 1. A steel cylinder 5 is arranged on the anchor rod 1, and the steel cylinder 5 is located between the flange 2 and the uppermost screw anchor plate 3. The anchor rod 1 penetrates the steel cylinder 5 from top to bottom and is coaxial with the central axis of the steel cylinder 5. The steel cylinder 5 is a hollow structure with openings at both ends, and concrete is filled between the inner wall of the steel cylinder 5 and the anchor rod 1 to form a short column.

[0033] The composite foundation is suitable for situations with heavy loads. The upper short piles can be assembled or cast-in-place. The steps are as follows:

[0034] S01. The cylindrical steel tube 5 with openings at both ends is placed on the foundation surface;

[0035] S02. Use a large diameter spiral drill bit to dig a hole downward in the steel cylinder 5;

[0036] S03. Press the steel cylinder 5 downward into the foundation (since the soil on the upper part of the foundation is relatively soft, and after the hole is formed in the steel cylinder 5, only a thin soil wall remains between the side wall of the hole and the side wall of the steel cylinder 5, and the steel cylinder 5 can be easily pressed in);

[0037] S04. Clean the debris in the hole;

[0038] S04. Drilling a screw anchor foundation into the hole;

[0039] S05 pouring concrete or placing precast concrete blocks 6;

[0040] When pouring concrete, the steel cylinder 5 and the anchor rod 1 are connected and fixed by the poured concrete;

[0041] When the prefabricated concrete blocks 6 are used, mortar or adhesive of the same strength may be injected between the prefabricated concrete blocks 6 and between the prefabricated concrete blocks 6 and the anchor rods 1 to achieve bonding and fixing.

[0042] The following table is a data comparison of the prefabricated short pile-spiral anchor composite foundation with cast-in-place piles and cap spiral anchors. From the data, we can see that the prefabricated short pile-spiral anchor composite foundation has the advantages of small size, less consumables and convenient construction.

[0043]

[0044] The above embodiments are only used to explain the concept of the present invention, rather than to limit the protection of the rights of the present invention. Any non-substantial changes to the present invention using this concept shall fall within the protection scope of the present invention.

Claims

1. An assembled short pile-screw anchor composite foundation, comprising an anchor rod, a plurality of screw anchor plates are arranged at the lower section of the anchor rod, and a flange is arranged at the top of the anchor rod, characterized in that: A steel cylinder is arranged on the anchor rod, and the steel cylinder is located between the flange and the uppermost spiral anchor plate. The anchor rod penetrates the steel cylinder from top to bottom and is coaxial with the central axis of the steel cylinder.

2. The assembled short pile-screw anchor composite foundation according to claim 1, characterized in that: The first form of the steel cylinder is a hollow and closed structure, and the bottom surface of the steel cylinder is a spiral anchor plate 2 with a diameter larger than the outer diameter of the cylinder body.

3. The assembled short pile-screw anchor composite foundation according to claim 1, characterized in that: The second form of the steel cylinder is a hollow structure with upper and lower ends opened, and the space between the inner wall of the steel cylinder and the anchor rod is filled with concrete.

4. A construction process for the assembled short pile-screw anchor composite foundation according to claim 2, characterized in that: The following steps are involved: The anchor rods are welded and fixed to the top and bottom surfaces of the steel cylinder respectively. There is no need for excavation and concrete pouring. The steel cylinder is screwed into the foundation together with the anchor rods.

5. A construction process for the assembled short pile-screw anchor composite foundation according to claim 3, characterized in that: The following steps are involved: Place the steel cylinder on the foundation surface; Use a large diameter spiral drill bit to drill a hole downward in the steel cylinder; Press the steel cylinder down into the foundation; Clean the debris in the hole; Drill the screw anchor foundation into the hole; Concrete is poured or precast concrete blocks are placed, and the precast concrete blocks are fixedly connected to each other and to the anchor rods.

Images