JPH01268920A - Caisson construction work - Google Patents

Abstract

PURPOSE:To enhance the efficiency of operations by a method in which the upper caissons formed by connecting segments with connectors are orderly set on the lower caisson to make the lower caisson a base, and then the segments are removed away. CONSTITUTION:An embankment 8 is constructed inside of a temporary cofferdam 6, and a lower caisson 1a having a cutting edge 9 on its lower end is set and settled gradually while excavating the inside of the caisson 1a. As the settlement proceeds, segments 3 are set on the caisson 1a while connecting them mutually with connectors in a breakable manner. The lower caisson 1a is taken as a base and the segments are gradually broken and removed from above by loosening the connectors.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a caisson construction method.

(Conventional technology) In the caisson construction method, a cylindrical caisson made of reinforced concrete with a cutting edge at the lower end is installed on the ground, and the earth and sand inside the caisson is excavated and removed while the caisson is lowered and placed on a designated supporting ground. This is a method of construction in which the structure is built up to a certain point, and this is used as the foundation of the structure. When constructing a foundation for a bridge using this caisson construction method, for example, the lower part of the caisson is used as the foundation and the upper part is removed.19. Conventionally, the removal method at this time was to use gunpowder or breakers to separate the upper caisson and remove it.

(Problems to be Solved by the Invention) However, as mentioned above, the use of explosives and breakers worsens the working environment, and also poses problems in terms of work efficiency, such as difficulty in removing crushed concrete blocks.

The present invention has been devised to effectively solve the above-mentioned problems, and its purpose is to provide a caisson construction method that allows the removal of the upper caisson to be carried out quickly while maintaining a good working environment.

(Means for Solving the Problems) In order to solve the above problems, the present invention sequentially constructs an upper caisson on a lower caisson having a cutting edge portion, and after sinking the lower caisson to the supporting ground, In a caisson construction method in which a caisson is used as the foundation of a structure and the upper caisson is then removed, the upper caisson is composed of a plurality of pre-formed segments, and the segments are fastened by fasteners when the lower caisson is sunk. After the lower caisson has been used as the foundation of the structure by being removably fastened to each other, the fasteners are loosened and the segments are sequentially disassembled and removed from the top.

(Function) In the caisson construction method constructed as described above, the upper caisson is constructed of a plurality of segments that can be disassembled, so the segments can be quickly disassembled and carried out simply by loosening the fasteners. Since the segments are reusable, construction costs can be reduced, and since there is no need to use explosives, a good working environment can be maintained.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows the caisson 1 used as the foundation of the bridge and the river bed 2.
The figure shows the state where the pipe has been sunk to a predetermined depth. This caisson 1 is made of reinforced concrete and has a cylindrical shape as shown in FIG. The caisson 1 is composed of a lower half of the caisson 1a, and an upper caisson 1b.

The upper caisson 1b consists of a large number of segments 3, and each segment 3 is removably fastened to each other by bolts 4 and bolts 5, as shown in FIG. This will be explained in more detail below.

A cylindrical temporary cofferdam 6 is driven into the riverbed 2 to a predetermined depth. The upper end of the temporary cofferdam 6 protrudes slightly above the water surface 7,
This prevents water from flowing into the inside of the temporary cofferdam 6. A built-up island 8 is constructed inside the temporary cofferdam 6 by removing the water inside and throwing earth and sand into it, and the caisson 1 is sunk from this built-up island 8.

The lower caisson 1a of the caisson 1 has a cutting edge 9 at its lower end, and its length is set to the length of the foundation to be constructed. This blade opening 9 is for reducing sinking resistance.

The upper caisson 1b has a large number of ready-made reinforced concrete segments 3 that can be disassembled arranged in the circumferential direction, and
It is constructed by stacking layers in the vertical direction. Four portions 17 are formed on the inner wall 3a of the segment 3, as shown in FIG. The upper and lower side walls 3b of the four parts 17 have insertion holes 1 in the vertical direction.
8 is formed, and this insertion hole 18 is continuous with the insertion hole 18 of another vertically adjacent segment 3. The upper and lower segments 3 are fastened to each other by bolts 4 inserted into two consecutive insertion holes 18 and nuts screwed onto the ends of the bolts 4. Furthermore, the above-mentioned through holes are similarly formed in the left and right side walls of the four parts 17, and the left and right segments 3 are fastened to each other by similar bolts and nuts. The lowermost segment 3 has a nut 2 attached to an anchor bolt 19 protruding from the upper end of the lower caisson 1a.
It is fixed at 0.

Attach sealing material to the upper, lower, left, and right joint surfaces of segment 3 as necessary for waterproofing. This sealing material should be attached to the center of the joint surface as much as possible.

Further, the joint portion inside the joint surface may be further filled with caulking material.

Upper caisson 1 as a temporary wall consisting of segments 3
6 functions as a press-fit bearing wall when it is sunk, and as a water-stop wall after it is sunk.

Next, the construction procedure of the caisson construction method of the present invention will be explained one by one. First, as shown in FIG. 1, after constructing the built-up island 8 inside the temporary cofferdam 6, the lower caisson 1a is constructed according to the conventional caisson construction method as described above.

Incidentally, the lower caisson 1a may be installed by dividing it into several lots in the vertical direction to the position and forming it by pouring concrete, or by integrating it in advance. Then, while excavating the inside of the lower caisson 1a,
The lower caisson 1a is gradually lowered, and as the lower caisson 1a is lowered, the segments 3 are stacked on top of the lower caisson 1a.

This process is repeated in order to sink the lower caisson 1a to the required depth as shown in FIG. This sinking work can be carried out efficiently because the segments 3 can be connected to each other by simply tightening the bolts 4.

Next, as shown in Fig. 4, a bottom plate 13 is formed at the inner bottom of the lower caisson 1a, a filling concrete 11 is filled on top of this bottom plate 13, and a top plate 12 is constructed at the upper end of the lower caisson 1a to form the foundation of the bridge. Then, the pier 10 is constructed on the top plate 12.

After completing the construction of the pier 10, the segments 3 of the upper caisson 1b are disassembled in order from the top. Segment 3 can be easily disassembled by simply loosening bolt 4. The disassembled segment 3 will be lifted up with a crane and removed. At this time, since the size of the segment 3 is constant, the removal work can be easily and efficiently performed. In addition, compared to destruction and removal using conventional breakers, there is no noise, there is no need to construct large-scale, solid work scaffolding, and there is no need for reinforcing bars on concrete blocks, making removal work very easy. In addition, when disassembling the upper caisson 1b, the construction island 8 is excavated and earth is removed accordingly, and when the disassembly of the segment 3 is completed, earth is filled up to two sides of the river bed within the temporary cofferdam 6, as shown in Fig. 5. After that, the temporary cofferdam 6 will be removed and the construction will be completed.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified in various ways.
For example, the cross-sectional shape of the caisson 1 may be circular, elliptical, rectangular, or the like. Further, as fasteners for fastening the segments 3 to each other, in addition to bolts and nuts, connecting plates, support beams, etc. may be used in combination.

(Effects of the Invention) The present invention consists of a plurality of disassembleable segments for the upper caisson to be finally removed, which facilitates the construction, disassembly, and removal of the upper caisson, thereby shortening the construction period. In addition, since no explosives or breakers are used, the work environment can be maintained in a good condition.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a vertical cross-sectional view of the right half of the caisson when the submergence is completed, Fig. 2 is a cross-sectional view taken along the line ■-■ in Fig. 1, Fig. 3 is a detailed sectional view of a portion of Fig. 1, Fig. 4 is a front view of the pier, and Fig. 5 is a front view of the pier after completion of construction. 1...Caisson 1a...Lower caisson 1b...Upper caisson 3...Segment 4...Bolt 5...Nut 6...・Temporary deadline 8・・・・・・Construction
Island 10... Bridge pier patent applicant Obayashi Co., Ltd. Agent
People Patent Attorney - Ken Iro
Patent Attorney Masatoshi Matsumoto [Figure 4 Figure 1 Figure Soviet Army Figure 2 Figure 5

Claims (1)

[Claims] A caisson in which an upper caisson is sequentially constructed on a lower caisson having a cutting edge, and after the lower caisson is sunk to supporting ground, the lower caisson is used as the foundation of a structure, and then the upper caisson is removed. In the construction method, the upper caisson is composed of a plurality of pre-formed segments, and the segments are removably fastened to each other by fasteners when the lower caisson is sunk,
A caisson construction method characterized in that after the lower caisson is used as the foundation of the structure, the fasteners are loosened and the segments are sequentially disassembled and removed from the upper part.