Caisson cutting edge hardware

Abstract

To provide a caisson cutting-edge fitting capable of improving adhesion between the cutting edge fitting of a caisson installed at a cutting edge portion and a concrete base.SOLUTION: The caisson cutting-edge fitting is a caisson cutting-edge fitting 10 that includes: an annular outer peripheral frame portion 10a; and an annular inner peripheral frame portion 10b that has a shape that the bottom end is connected to the outer peripheral frame portion 10a and the top is open, and the same tapers outwards towards the bottom end. The caisson cutting-edge fitting is formed extending in the circumferential direction in the inner peripheral frame portion 10b, and has a groove portion V that is concave when viewed from the inside space surrounded by the inner peripheral frame portion 10b. With this, when the poured base concrete C is filled into the groove V, the base concrete C becomes caught in the groove V. The adhesion between the caisson cutting-edge fitting 10 and the base concrete C is improved.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a caisson cutting tool installed at the cutting edge portion located at the deepest part of a caisson body submerged in the ground.

Background Art

[0002] When constructing underwater structures or underground structures such as bridge piers and breakwaters, concrete or steel caissons are used. A caisson is a cylindrical structure with a rectangular or circular horizontal cross-section of the body. The caisson method is a construction method in which the ground inside the hollow of the caisson body is excavated and sunk, and the caisson body is constructed on the upper part repeatedly to construct a foundation structure.

[0003] Foundation structures using caissons have characteristics such as large rigidity and small displacement because of their large cross-section compared with other foundation structures, and both large horizontal resistance and large vertical support force can be expected.

[0004] Now, the cutting edge portion formed at the deepest part of the caisson body that is vertically excavated in the ground and submerged in the ground is protected by a cutting tool (caisson cutting tool) made of a steel plate because the load concentrates during sinking. This cutting tool is composed of an annular outer peripheral frame portion and an inner peripheral frame portion. The inner peripheral frame portion is tapered to widen outward toward the lower end, and the contact surface of the inner peripheral frame portion with the ground is made smooth so as not to cause resistance during sinking.

[0005] Regarding caissons, for example, the technique described in Patent Document 1 (Japanese Patent No. 6423045) is known.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Now, the inner circumferential frame of the caisson's cutting edge fittings has a smooth surface, making adhesion with the concrete poured after sinking uncertain. In the open caisson method (a method in which the caisson structure is gradually submerged while excavating the hollow interior), excavation is carried out under atmospheric pressure, and after reaching a predetermined depth, the base concrete is poured onto the bottom surface of the hollow interior. In this case, if the base concrete does not integrate with the caisson's cutting edge fittings, there is a risk that groundwater may flow into the caisson from between the base concrete and the cutting edge fittings.

[0008] Therefore, improving the adhesion between the cutting edge hardware and the base concrete is a challenge.

[0009] The present invention has been made in light of the above-mentioned technical background, and aims to provide a technology that can improve the adhesion between the caisson cutting edge fitting installed at the cutting edge and the base concrete. [Means for solving the problem]

[0010] To solve the above problems, the caisson cutting edge fitting according to claim 1 is a steel caisson cutting edge fitting installed at the cutting edge located at the deepest part of a caisson structure that is sunk into the ground, comprising: an annular outer frame portion; an annular inner frame portion connected to the outer frame portion at its lower end, with an opening at the top and tapering outward toward the lower end; and extending in the circumferential direction within the inner frame portion Continuously around the entire circumference A groove is formed and has a concave shape when viewed from the internal space surrounded by the inner circumferential frame. The inner circumferential frame portion comprises an upper inner frame located on the upper side, a lower inner frame provided below the upper inner frame with a gap between them, and a groove steel material attached between the upper inner frame and the lower inner frame to form the groove. It is characterized by the following:

[0013] Claim 2 The caisson cutting edge fitting according to the invention described above Claim 1 In the invention described above, the steel material for the groove is a plate-shaped steel material attached across the upper inner frame and the lower inner frame.

[0014] Claim 3 The caisson cutting edge fitting according to the invention described above Claim 1 In the invention described above, the groove steel material is an angle steel or channel steel installed between the upper inner frame and the lower inner frame in a direction that faces the internal space into the recess. [Effects of the Invention]

[0015] According to the present invention, when the poured base concrete is filled into the groove, the base concrete becomes caught in the groove, which improves the adhesion between the caisson cutting edge fitting installed at the cutting edge and the base concrete, thereby improving the watertightness of the interface. [Brief explanation of the drawing]

[0016] [Figure 1] This is an explanatory diagram illustrating the general procedure for constructing a caisson using a caisson cutting edge fitting according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing a caisson cutting edge fitting according to one embodiment of the present invention. [Figure 3] This is a cross-sectional view showing the poured base concrete and the groove formed in the inner circumferential frame of the caisson cutting edge fitting. [Figure 4] This is a cross-sectional view showing a modified example of a caisson cutting edge fitting according to one embodiment of the present invention. [Figure 5] This is a cross-sectional view showing another modified example of the caisson cutting edge fitting according to one embodiment of the present invention. [Modes for carrying out the invention]

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings used to illustrate the embodiments, the same reference numerals are generally used for identical components, and repeated descriptions of such components will be omitted.

[0018] Figure 1 is an explanatory diagram illustrating the general procedure for constructing a caisson using the caisson cutting edge fitting according to this embodiment.

[0019] The caisson construction method of this embodiment is called the open caisson construction method. In this method, while excavating the hollow interior of a cylindrical caisson body constructed and installed on the ground by machine (or manually), the process of gradually sinking the caisson body is repeated. After reaching a predetermined depth, the caisson is used as a foundation structure.

[0020] Specifically, after constructing a sinking anchor (not shown) that serves as the sinking reaction force of the caisson body S, the ground G is leveled and the platter plate P is installed. Then, a cutting edge metal object (caisson cutting edge metal object) 10 composed of an annular outer peripheral frame portion 10a and an inner peripheral frame portion 10b that are connected to each other at the lower end and open upward is installed at the sinking location, and concrete is placed to construct a cutting edge portion S1 that is the caisson body S located at the deepest part of the caisson (Fig. 1(a)). Details of the cutting edge metal object will be described later.

[0021] After constructing the cutting edge portion S1, a pressing-in facility is installed, and the sinking anchor and a pressing-in device (not shown) are connected. Then, after removing the platter plate P, while excavating the ground in the hollow interior with a clam shell (excavator) T, the pressing-in of the sinking anchor is started using the reaction force. When the cutting edge portion S1 is sunk to a predetermined depth, an inner formwork and an outer formwork are installed above the cutting edge portion S1, reinforcing bars are arranged between the inner formwork and the outer formwork, and concrete is placed to construct the next lot of caisson body S2 (Fig. 1(b)).

[0022] The pressing-in of the caisson body S while excavating and the construction of the next lot of caisson body S on the upper part of the caisson body S are repeated. In the case shown in the figure, when three caisson bodies S2, S3, and S4 are constructed above the cutting edge portion S1 and the sinking is completed after reaching a predetermined depth, as shown in Fig. 1(c), bottom slab concrete C is placed on the bottom surface of the hollow interior. Then, as shown in Fig. 1(d), contact grout R is injected into the gap between the outer peripheral surface of the caisson body S and the ground, and the construction of the caisson as a foundation structure is completed.

[0023] Now, the steel cutting edge fitting 10 installed at the cutting edge S1 located at the deepest part of the cylindrical caisson structure S which is sunk into the ground, comprises, as shown in Figure 2, an outer circular frame portion 10a that is annular in plan view and an inner circular frame portion 10b that is also annular in plan view. The outer circular frame portion 10a and the inner circular frame portion 10b are connected to each other at their lower ends and are open at the top, and the inner circular frame portion 10b is tapered, widening outwards towards the lower end.

[0024] Furthermore, anchor bars W are appropriately placed within the space formed by the outer frame portion 10a and the inner frame portion 10b to adhere to the poured concrete, thereby increasing its strength and integrating the cutting edge fitting 10 with the concrete.

[0025] The inner circumferential frame portion 10b has a recessed portion, i.e., a groove portion V, which is formed when viewed from the internal space surrounded by the inner circumferential frame portion 10b. In this embodiment, the groove portion V is substantially horizontal and extends in the circumferential direction, and is formed continuously around the entire circumference of the inner circumferential frame portion 10b.

[0026] To describe in detail the groove V formed in the inner circumferential frame portion 10b, the inner circumferential frame portion 10b comprises an upper inner frame 10b-1 located above, and a lower inner frame 10b-2 provided below the upper inner frame 10b-1 with a gap between them. A groove-forming steel member 10b-3, which forms the groove V, is attached between the upper inner frame 10b-1 and the lower inner frame 10b-2. In the case shown in Figure 2, the groove-forming steel member 10b-3 is a plate-shaped steel member 10b-3a attached so as to straddle the upper inner frame 10b-1 and the lower inner frame 10b-2.

[0027] In this embodiment, since the groove V described above is formed in the cutting edge fitting 10, the aforementioned base concrete C is poured to a thickness that encloses the groove V. When poured in this manner, as shown in Figure 3, the base concrete C is filled into the groove V, causing it to catch on the groove V, thereby improving the adhesion between the cutting edge fitting 10 and the base concrete C. As a result, the watertightness of the interface between the cutting edge fitting 10 and the base concrete C is improved, making it difficult for groundwater to flow into the caisson from between the base concrete C and the cutting edge fitting 10.

[0028] Furthermore, if soil and sand remain attached to the inner perimeter frame 10b when the base concrete C is poured, the adhesion between the cutting edge fitting 10 and the base concrete C will be poor. Therefore, prior to pouring the base concrete C, it is desirable to use an ultrasonic measuring device or the like to investigate the presence and location of soil and sand on the inner space side surface of the inner perimeter frame 10b (i.e., the side to which the base concrete C will adhere) (soil and sand confirmation step), and to remove the soil and sand using a soil and sand removal device or the like (soil and sand removal step).

[0029] Furthermore, as mentioned above, since the base concrete C becomes caught in the groove V, improving the adhesion between the cutting edge fitting 10 and the base concrete C, the soil confirmation process and the soil removal process may be performed only on the groove V, rather than on the wide area of ​​the inner space side of the inner circumferential frame portion 10b.

[0030] Although the invention made by the present inventors has been specifically described above based on embodiments, the embodiments disclosed herein are illustrative in all respects and are not limited to the disclosed art. That is, the technical scope of the present invention should not be interpreted restrictively based on the description in the embodiments above, but rather should be interpreted in accordance with the claims, and includes art equivalent to the art described in the claims and all modifications that do not depart from the gist of the claims.

[0031] For example, the steel material 10b-3 for the groove is not limited to the plate-shaped steel material 10b-3a, but various steel materials capable of forming the groove V can be applied. For example, as shown in Figure 4, an angle steel 10b-3b installed between the upper inner frame 10b-1 and the lower inner frame 10b-2, or as shown in Figure 5, a channel steel 10b-3c installed between the upper inner frame 10b-1 and the lower inner frame 10b-2 can be applied. When applying the angle steel 10b-3b or the channel steel 10b-3c, they should be installed between the upper inner frame 10b-1 and the lower inner frame 10b-2 in a direction that faces the internal space, as shown in the figure.

[0032] Furthermore, the groove V formed in the inner circumferential frame portion 10b does not have to be substantially horizontal, nor does it have to be formed continuously around the entire circumference of the inner circumferential frame portion 10b. However, if it is substantially horizontal and formed continuously around the entire circumference, the adhesion between the cutting edge fitting 10 and the base concrete C will be further improved, and the watertightness of the interface will be further enhanced.

[0033] In this embodiment, four caisson structures S2, S3, and S4 are constructed above the cutting edge S1, which is the deepest part of the caisson structure. However, the number of caisson structures S that are constructed is not limited to four. [Industrial applicability]

[0034] Caissons using the caisson cutting edge fittings according to the present invention can be used when constructing underwater structures such as bridge piers, quays, and breakwaters, as well as various underground structures. [Explanation of symbols]

[0035] 10. Caisson caisson fittings 10a Outer frame section 10b Inner Circumferential Frame 10b-1 Upper inner frame 10b-2 Lower inner frame 10b-3 Steel material for grooves 10b-3a Plate-shaped steel material (steel material for grooves) 10b-3b Angle steel (steel material for grooves) 10b-3c Channel steel (steel material for grooves) C. Base concrete G Ground P dish plate R Contact Grout S Caisson structure S1 Cutting edge section (caisson body) S2, S3, S4 Caisson Structure V groove W anchor rebar

Claims

1. A steel caisson cutting edge fitting installed at the cutting edge located at the deepest part of the caisson structure that is sunk into the ground, An annular outer frame portion, The aforementioned outer circumferential frame portion is connected to the lower end, and the upper part is open, and the annular inner circumferential frame portion is tapered and widens outward toward the lower end, The inner circumferential frame portion is formed to extend circumferentially and continuously over its entire circumference, and has a groove portion that is concave when viewed from the internal space surrounded by the inner circumferential frame portion, It has, The aforementioned inner circumferential frame portion is The upper inner frame located on the upper side, A lower inner frame is provided below the upper inner frame, with a gap between it and the upper inner frame. A steel material for forming the groove is installed between the upper inner frame and the lower inner frame, Equipped with, A caisson cutting edge fitting characterized by the following features.

2. The steel material for the groove is This is a plate-shaped steel material attached across the upper inner frame and the lower inner frame. The caisson cutting edge fitting according to feature 1.

3. The steel material for the groove is An angle steel or channel steel is installed between the upper inner frame and the lower inner frame in a direction that faces the internal space. The caisson cutting edge fitting according to feature 1.

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