Press-in type open caisson

Abstract

To stably press a caisson in.SOLUTION: A cylindrical press-in type open caisson extending in the up-down direction includes a cutting edge provided at the lower end of the press-in caisson, a friction cut section provided on the entire outer surface of the press-in caisson at a predetermined height from the lower end and at a predetermined thickness from the outer surface outward, and multiple plate-shaped protrusion sections provided at predetermined intervals in the circumferential direction of the outer surface, at a predetermined width in the circumferential direction of the outer surface, at a predetermined height from the upper end of the friction cut section, and with a thickness less than the thickness of the friction cut section.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a press-fit open caisson. [Background technology]

[0002] In the above technical field, Patent Document 1 discloses that by adjusting the protruding length of the friction jig, it is possible to adjust the amount of over-digging and control the posture (paragraphs

[0033] ,

[0045] , etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-138409 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology described in Patent Document 1 above was unable to prevent the caisson from rotating, and was therefore unable to press the caisson in stably. [Means for solving the problem]

[0005] In order to achieve the above object, the press-fit open caisson according to the present invention is A cylindrical press-fit open caisson extending in the vertical direction, A cutting edge provided at the lower end of the press-fit caisson; A friction cut portion provided on the entire outer peripheral surface of the press-fit caisson at a predetermined height from the lower end and at a predetermined thickness outward from the outer peripheral surface; a plurality of plate-shaped protrusions provided at predetermined intervals in the circumferential direction on the outer circumferential surface, at a predetermined height from the upper end of the friction cut portion, and at a thickness equal to or less than the thickness of the friction cut portion; Equipped with: [Effects of the Invention]

[0006] According to the present invention, the caisson can be pressed in stably. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram for explaining an overview of a press-fit open caisson construction method using a press-fit open caisson according to a preferred embodiment of the present invention. [Figure 2] 1 is a diagram for explaining the construction procedure of a press-fit open caisson method using a press-fit open caisson according to a preferred embodiment of the present invention. [Figure 3] This is a schematic cross-sectional view to explain the configuration of the slit at the tip of a press-fit open caisson in a preferred embodiment of the present invention. [Figure 4] This is an oblique view to explain the configuration of the slit at the tip of a press-fit open caisson in a preferred embodiment of the present invention. [Figure 5] This is a top view to explain the configuration of the slit at the tip of a press-fit open caisson in a preferred embodiment of the present invention. [Figure 6] This is a diagram to explain the rotation of the caisson body by the cutting edge of the caisson, which is the underlying technology of the press-fit open caisson in a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the configurations, numerical values, processing flows, functional elements, etc. described in the following embodiments are merely examples, and are open to modification and alteration, and are not intended to limit the technical scope of the present invention to the following description.

[0009] A press-fit caisson according to a preferred embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG.

[0010] <Prerequisite technology> First, with reference to Fig. 6, the underlying technology of this embodiment will be described. Excavation using a shield tunneling machine is carried out by starting the shield tunneling machine from a starting shaft and continuing to excavate a destination shaft. One construction method for excavating a starting shaft or a destination shaft is the press-in open caisson method. This method involves using a machine or other device to excavate the inside of a cylindrical reinforced concrete caisson constructed above ground, gradually lowering the caisson, and pouring concrete into the caisson once it reaches the supporting layer, using the caisson itself as a foundation structure. A steel cutting edge is formed at the bottom of the caisson.

[0011] In the press-in open caisson method, multiple anchors are driven into the ground, a cutting edge ring is installed inside the area where the anchors are installed, and the cutting edge ring is pushed into the ground using a jack while removing the reaction force from the anchors. As the caisson is pushed into the ground, the soil inside the caisson is excavated using a bucket or other tool. Concrete is then poured over the cutting edge, and the top of the concrete is pushed down again with a jack, propelling it downward until it reaches the specified depth. The tip of the cutting edge has a friction-cut structure to reduce resistance from the ground.

[0012] However, as shown in Figure 6, when the cutting edge 16 is pressed into the ground, the ground may contain large gravel 20. In such cases, the cutting edge 16 encounters resistance from the gravel 20, causing the caisson itself to rotate horizontally. When the caisson itself rotates in this way, the rebar installed inside the foundation structure during construction also twists, resulting in a decrease in the strength of the foundation structure. Another problem is that when the NOMST (Novel Material Shield-cuttable Tunnel-wall System) construction method is used, the starting position of the shield machine may shift.

[0013] <Present Embodiment> Referring to FIG. 1 , an overview of the press-in open caisson used in the press-in open caisson construction method according to this embodiment will be described. The press-in open caisson construction method is a construction method in which a reinforced concrete framework constructed above ground is repeatedly subjected to controlled press-in and excavation into the ground to construct a structure to a predetermined depth. This construction method allows safe and reliable construction through posture control. FIG. 1 shows a schematic diagram of a press-in open caisson 1, which includes a bucket-type excavator 11, a press-in device 12, a sinking device 13, sinking anchors 14, a caisson framework 15, a cutting edge 16, an inner scaffolding 17, an outer scaffolding 18, and an impact barrier 19. The press-in device 12 and the sinking device 13 are used to sink the sinking anchors 14. Furthermore, when excavating soil 10, the soil 10 inside the caisson is excavated using a bucket-type excavator 11. Once the installation of the sinking anchors 14 is complete, the inner scaffolding 17 and outer scaffolding 18 are set up and construction of the caisson begins.

[0014] Next, the construction procedure of the press-fit open caisson method will be described with reference to Figs. 2(1) to (12).

[0015] (1) Preliminary drilling (sand replacement): Here, a fully rotary all-casing drilling machine is used to drill to the specified depth, and then the casing tube is pulled out while filling the inside of the casing with sand (this procedure is carried out as needed).

[0016] (2) Sinking anchor work: The sinking anchor that serves as the sinking reaction force for the press-in open caisson 1 is installed using rotary percussion.

[0017] (3) Installation work (counter plate): After correcting the ground displacement at the cutting edge, install the counter plate.

[0018] (4) Construction of cutting edge: The cutting edge hardware is accurately installed at the installation point, and scaffolding is set up around it to construct the cutting edge.

[0019] (5) Press-in equipment set: After the cutting edge is constructed, the inner scaffolding 17 and the outer scaffolding 18 are partially removed. Press-in equipment is installed, and the submerged anchor and the press-in device are connected.

[0020] (6) Excavation and Press-in: While excavating the inside of the press-in open caisson 1 using the heavy clamshell, controlled press-in is started using the sinking anchor as a reaction force.

[0021] (7) Installation of work scaffolding: After removing the press-fitting device, install the inner scaffolding 17 in the designated location to secure assembly space for the next lot.

[0022] (8) Construction of the nth lot structure: After the work scaffolding is set up, the structure is constructed in the following order: inner formwork, reinforcing bars, formwork, pouring fresh concrete, and curing.

[0023] (9) Nth lot excavation and press-in: After removing the work scaffolding and inner scaffolding, the inside of the open caisson is excavated using a heavy clamshell, and controlled press-in is performed. After that, steps (7) to (9) are repeated.

[0024] (10) Reaching the specified depth: The press-fit open caisson 1 reaches the specified depth and the installation is completed.

[0025] (11) Underwater concrete placement: The slime that has settled at the bottom of the hole is removed with a bucket (using a submersible pump if necessary), and the bottom slab concrete is placed underwater using the plunger tremie method. The use of underwater non-segregating concrete ensures excellent quality, including watertightness and flatness.

[0026] (12) Surface CG - Pouring of adjusted concrete: Concrete grout is injected into the gap between the outer surface of the open caisson and the ground. The water in the hole is drained and adjusted concrete is poured to complete the process.

[0027] The press-fit open caisson 1 will be described with reference to Figures 3 to 5. The press-fit open caisson 1 has a tubular or cylindrical shape that extends in the vertical direction. The caisson body 15 of the press-fit open caisson 1 is also tubular or cylindrical, with a hollow space inside. A cutting edge 16 is provided at the lower end of the caisson body 15, and the cutting edge 16 is the part that penetrates into the ground first during the installation of the press-fit open caisson 1. During installation, an extremely large concentrated load acts on the cutting edge 16, and therefore the cutting edge 16 is an important part in the structure of the press-fit open caisson 1.

[0028] The friction cuts 22, 23 are provided over the entire outer peripheral surface of the press-fit open caisson 1 at a predetermined height from the lower end and at a predetermined thickness extending outward from the outer peripheral surface. That is, two-stage friction cuts 22, 23 are provided outside the cutting edge 16 (the lower end of the outer peripheral surface of the caisson body 15). Then, from the bottom, two stages of friction cuts 22, 23 are provided in the order of the first stage friction cut 22 and the second stage friction cut 23. The thickness of the first stage friction cut 22 is either thicker than or equal to the thickness of the second stage friction cut 23. These thicknesses are measured in the direction from the outer peripheral surface of the caisson body 15 outward.

[0029] The second-stage friction cut 23 extends upward (toward the ground) from the upper end of the first-stage friction cut 22. In other words, the first-stage friction cut 22 is provided on the lower side, and the second-stage friction cut 22 is provided above the first-stage friction cut 22. Furthermore, both the first-stage friction cut 22 and the second-stage friction cut 22 are provided around the entire circumferential direction of the cylindrical caisson body 15.

[0030] By providing friction cuts 22, 23 on cutting edge 16, a hole larger than the following caisson body 15 is drilled, thereby reducing friction between the outer surface of caisson body 15 and the ground when pressing in caisson body 15. In other words, when a hole the same size as the outer diameter of caisson body 15 is drilled, friction occurs between the outer surface of caisson body 15 and the ground, so friction cuts 22, 23 are provided to reduce this friction.

[0031] The plate-like protrusions 21 are elongated guide steel plates provided on the outer surface (peripheral surface) of the cutting edge 16 (press-fit open caisson 1 (caisson body 15)), and are provided at predetermined intervals in the circumferential direction. The size of the plate-like protrusions 21 is, for example, a plate-like member with a thickness of 12 mm, a height of 1,884 mm, and a width of 50 mm, but the size of the plate-like protrusions 21 is not limited to this. For example, the thickness is about 10 mm to 50 mm.

[0032] The length from the lower end of the caisson body 15 to the upper end of the plate-shaped projection 21 is 2,000 mm. In other words, the height of the first-stage friction cut 22 is 116 mm. The thickness of the plate-shaped projection 21 may be any thickness as long as the outer peripheral surface of the plate-shaped projection 21 is not positioned outside the outer peripheral surface of the first-stage friction cut 22. The plate-shaped projection 21 is welded to the cutting edge 16.

[0033] Furthermore, as shown in Figure 5, a plurality of plate-shaped protrusions 21 are provided (provided in the form of slits) at equal intervals on the outer peripheral surface of the caisson body 15 (cutting edge 16). In other words, the plate-shaped protrusions 21 are arranged so as to be rotationally symmetric on the outer peripheral surface of the caisson body 15. While the figure shows an example in which eight plate-shaped protrusions 21 are provided, the number of plate-shaped protrusions 21 is not limited to eight and may be any plural number. Furthermore, the arrangement of the plate-shaped protrusions 21 is not limited to a rotationally symmetric arrangement and may be any arrangement.

[0034] According to this embodiment, it is possible to suppress tilting, rotation, and misalignment of the press-fit open caisson when it is pressed in. In addition, a slit that resists lateral movement is provided near the cutting edge of the press-fit open caisson, so it is possible to suppress rotation that occurs when the cutting edge rests on gravel or the like.

[0035] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above-described embodiments and can be modified as appropriate. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. Furthermore, systems or devices that combine separate features included in each embodiment in any manner are also included in the scope of the present invention. [Explanation of symbols]

[0036] 1 Press-fit open caisson 10. Sediment 11 Bucket type excavator 12 Press-fitting equipment 13 Submersion equipment 14 Submerged anchor 15 Caisson body 16 Blade mouth 17 Inner scaffolding 18 External scaffolding 19 Impact barrier 20 Gravel 21 Plate-shaped protrusion 22 Friction Cut 23 Friction Cut

Claims

1. A cylindrical press-fit open caisson extending in the vertical direction, A cutting edge provided at the lower end of the press-fit open caisson; A friction cut provided on the entire outer peripheral surface of the press-fit open caisson at a predetermined height from the lower end and a predetermined thickness from the outer peripheral surface to the outside; A plurality of plate-shaped protrusions provided at predetermined intervals in the circumferential direction of the outer circumferential surface, at a predetermined height from the upper end of the friction cut, and at a thickness equal to or less than the thickness of the friction cut; A press-fit open caisson equipped with a

2. A press-fit open caisson as described in claim 1, wherein the plate-shaped protrusion is welded to the cutting edge.

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