JPS5948252B2 - Caisson installation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a caisson installation method for installing a caisson on a rubble foundation prepared at the bottom of a water body.

Generally, rubble foundations are used in the installation work of caissons on the seabed.

To construct this rubble foundation, it is usually necessary to load the rubble from the sea using a boat or the like, and then level the top surface of the rubble foundation evenly.

Traditional methods of leveling the surface of the rubble foundation include manual leveling by divers and screeding, but manual leveling by divers has a limit on the amount of time required for diving. It is not efficient as it involves moving rubble one by one by hand, and with the current shortage of divers, it is becoming difficult to secure such personnel, especially for large-scale construction projects that require shortening the construction period. There are problems such as difficulty in construction.

Furthermore, as coastlines have been developed in recent years, construction work is being required to be carried out in areas with poor sea conditions in terms of waves and water depth, and construction plans are being made that make leveling work by divers impossible.

In addition, the leveling method using a screed involves moving a horizontal hopper to the surface of the rubble foundation and laying pebbles to level the surface in the horizontal direction, but this requires large-scale leveling, which requires a large machine. , and as the rubble becomes larger, the size of the machine becomes exponentially larger and becomes more expensive.

In addition, the leveling process is not always satisfactory and auxiliary methods are required.Moreover, the preparatory work is large-scale, and the investment amount for equipment that can only be used for large-scale construction is large, making it difficult to use economically. In addition, there were problems such as incorrect input management resulting in return work.

The present invention has been developed in consideration of the problems of various conventional construction methods as mentioned above.
Caisson installation that simplifies manual or mechanical leveling of the rubble foundation surface when large rubble is used, especially when installing large caissons in deep water areas, and allows for stable caisson installation. This method is intended to provide a construction method, and its gist is to form a protrusion for temporary support on at least the periphery of the bottom of the caisson, and to provide continuous or discontinuous grooves in the center of the caisson. The lower end of the mortar injection and drainage hole is opened in the groove, and an airtight membrane is stretched loosely on the bottom of the caisson, and air is sucked through the injection and drainage hole to tightly fit the membrane into the space at the bottom of the caisson. Then, the caisson is built on a rubble foundation with rubble stones thrown onto the foundation ground to a desired height, and temporary support parts for the caisson are formed at several places on the top surface corresponding to the protrusions for temporary support on the bottom of the caisson. The caisson installation method is characterized in that mortar is injected into the membrane through the injection hole and the bottom of the caisson fills the gap between the rubble foundations.

Next, an example of implementation of the present invention will be described with reference to the drawings.

First, as shown in Fig. 1, rubble 1 is thrown onto the foundation ground at the bottom of the water using a boat or the like as in the past.

When introducing this rubble, the input is controlled so that it has a shape close to the cross-sectional shape of the desired rubble foundation.

Temporary caisson support portions 3 are formed at several locations on the surface of the rubble foundation 2 thrown in this way.

The height of this temporary receiving part 3 is precisely set according to the installation height of the caisson A to be installed, and the formation of the temporary receiving part of the caisson is, for example, by using rubble as shown in Fig. 2 A. 1 may be leveled as much as necessary to form the caisson temporary support part 3.Also, sand bags 5 may be piled up on the surface of the rubble foundation 2 constructed by the government as shown in the opening of Figure 2. As shown, piles 4 may be used, and in this case, the membrane may be erected by driving them into the ground before putting in the rubble, or by driving them after putting in the rubble.

The work of forming these temporary caisson support parts 3 was carried out by divers, and the height was measured using a conventional method and was approximately 10 cm.
Accurately finish within a certain error range.

In this way, the bottom surface of the caisson A is temporarily received on the protruding caisson temporary receiving portion 3, and as shown in FIGS. It is formed in one piece.

This protrusion 6 is formed continuously at least at the peripheral edge of the bottom of the caisson, and a space a is formed by recessing the center of the bottom.

Further, a groove 7 having a substantially semicircular cross section is formed in the recessed portion of the bottom surface of the caisson.

A plurality of grooves 7 are successively provided in a grid-like arrangement.

Note that they may be arranged in parallel without being continuous outside the grid.

The lower ends of the holes 8 for injecting and discharging mortar, air, etc. are opened at a plurality of locations in the groove 7.

This injection hole 8 passes through the vertical wall 9 of the caisson A.
It is opened at the upper end.

As shown in FIG. 7, the caisson A having such a structure is equipped with an airtight membrane 10 covering the entire bottom surface.

This membrane 10 is installed so as to be loose enough to fit at least closely along the inner surface of the space a at the bottom of the caisson, and its peripheral edge is fixed to the peripheral edge of the bottom of the caisson.

Further, this membrane 10 is installed at the same time as the caisson A is molded with concrete, and as shown in FIG. 5, concrete is poured after the membrane 10 is laid on the bottom surface 11a of the caisson form 11.

At this time, there is a partially slack portion 1 on the upper surface of the formwork bottom surface 11a.
2 may be folded.

Further, this membrane 10 has an air impermeable layer 10 as shown in FIG.
A and an air-permeable elastic layer 10b made of nonwoven fabric or other open-cell sponge material, etc., are installed on the bottom of the caisson with the air-permeable elastic layer 10b facing downward, and after the caisson is fabricated, it is floated with water in a dock. When demolding, water circulation to the bottom of the caisson is improved to facilitate demolding and to prevent damage to the membrane 10 during towing.

The membrane 10 may be attached at the time of molding the caisson or after the caisson is molded.

In this way, the caisson A equipped with the membrane 10 is floated above the water surface and towed to the desired installation location. At that time, the air inside is sucked through the above-mentioned injection and discharge hole 8, and the bottom surface of the caisson and the membrane 10 are The gap is evacuated, thereby keeping the membrane 10 in close contact with the inner surface of the space a. In this case, the slack of the membrane 10 is absorbed into the groove 7.

In this state, the caisson temporary support protrusion 6 is placed in contact with the caisson temporary support part 3 of the rubble foundation 2 described above.

Thereafter, the reduced pressure state of the injection/discharge hole 8 is released, and mortar 13 is injected through the injection/discharge hole 8' in the central portion.

The injection/discharge hole 8 is used for mortar injection inspection.

By injecting mortar in this manner, mortar 1 is placed between the bottom surface of the caisson A and the membrane 10 as shown in FIG.
3 is filled, the membrane 10 is pushed out and brought into close contact with the top surface of the rubble foundation 2, and the gap between the caisson A and the rubble foundation 2 is completely filled with mortar 13, and the caisson A and the earth and sand that will later be filled into the caisson membrane are filled. The weight will be evenly supported on the rubble foundation surface.

The caisson installation method of the present invention is configured as described above. Conventionally, the entire surface of the rubble foundation is leveled as a process before installing the caisson, and the leveling is rough leveling and regular leveling. However, with the present invention, it is only necessary to partially provide temporary caisson support parts, which greatly simplifies the diving work and eliminates the need for multiple steps of leveling work. This eliminates the need for additional equipment, allows for efficient work even in areas with poor sea conditions, and eliminates the need for many divers and other specialized technicians.Moreover, even large-scale construction can be completed in a short period of time. It is something that

In addition, when installing a caisson on a rubble foundation, it is first installed on several temporary supports, so the height accuracy of the temporary supports can be easily obtained, and therefore the caisson can be installed at the precisely high position. Furthermore, since mortar is filled between the bottom of the caisson and the rubble foundation, complete adhesion between the two is possible, resulting in extremely high stability.Furthermore, the mortar is injected into the airtight membrane. There is no leakage, reliable mortar filling is achieved, and reliability after installation is improved.

Furthermore, an upwardly recessed space is formed in the bottom of the caisson, and a groove is provided in the groove, and an injection hole is opened in the groove, and the pressure is reduced through the injection hole, thereby preventing membrane sag during towing. There is no downward movement, and the membrane is housed in the space and groove without sagging, so that no damage occurs during operation.

Furthermore, the grooves have various effects such as increasing and concentrating the laitance generated after filling with mortar, making it possible to treat it and improving the properties of concrete.

[Brief explanation of drawings]

The drawings show the implementation process of the present invention, and Fig. 1 is a cross-sectional view of the poured rubble foundation, Fig. 2 A to C are cross-sectional views showing different examples of temporary support parts, and Fig. 3 is a cross-sectional view of the poured rubble foundation. A cross-sectional view of the caisson, Figure 4 is an open bottom view, Figure 5 is a partial cross-sectional view of the same molded state, Figure 6 is a partial enlarged cross-sectional view of the membrane, Figure 7 is a partial cross-sectional view of the refitted state, and Figure 8 is a cross-sectional view of the state after mortar has been poured. 1...Rubble stone, 2...Rubble foundation, 3...
... Caisson temporary support part, 4 ... Pile, 5 ...
... Sand bag, 6 ... Protrusion, 7 ... Concave groove, 8 ... Injection hole, 9 ... Vertical wall, 10.
...Membrane, 10a...Air impermeable layer, 10b
......Air permeable elastic layer, 11...Caisson formwork, lla...Bottom surface, 12...Sagging portion, 13...Mortar, A...caisson, a...space.

Claims (1)

[Claims] 1. A protrusion for temporary reception is formed at least on the peripheral edge of the bottom of the caisson, a space is formed at the bottom by recessing the central part, and a plurality of grooves are provided continuously or discontinuously on the recessed bottom of the caisson. , the lower end of the mortar injection hole is opened in the groove, and an airtight membrane is loosely stretched over the bottom of the caisson, and air is sucked through the injection hole to tightly fit the membrane into the space at the bottom of the caisson. Then, the caisson was built to a desired height by dropping rubble on the foundation ground, and the caisson temporary support parts were formed at several places on the top surface corresponding to the temporary support protrusions on the bottom of the caisson. A caisson installation method characterized in that the caisson is installed on a foundation, and then mortar is injected into the membrane through the injection hole to fill the gap between the bottom of the caisson and the rubble foundation.