JPS5948251B2 - How to install a caisson - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for installing a caisson for the construction of a breakwater or seawall, and particularly to a method for reliably installing a large caisson on a mound with simple operations in deep water areas.

Generally, caissons used as breakwaters in shallow waters do not need to be very large because the water is shallow, and the mounds that support the caisson only need to be relatively small-scale rubble mounds.

Therefore, the base area of the caisson rubble mound was small, and the water pressure was not very high, so the leveling work was easy.

However, in recent years, it has become necessary to construct seawalls or associated breakwaters for constructing offshore artificial islands in deep waters of -50 m or more.

The caissons used in such deep water areas are becoming increasingly large.
For this reason, the mound that supports it must also form a large-scale rubble mound.

Therefore, the leveling work is extremely difficult because the base surface area of the rubble mound becomes large, the rubble itself becomes huge, and the water pressure is high.

In addition, the weight of the caisson itself is considerable, so if the base surface is slightly sloped or uneven, there is a risk that a large overcurrent will be applied to a part of the mound and the mound will collapse, so it is necessary to level the base surface. High precision is required.

The present invention was made in response to the above-mentioned demands, and its purpose is to facilitate leveling of the base surface of rubble mounds even in deep water areas and to achieve extremely high leveling accuracy. To provide a method for installing a caisson which can also securely and stably support the caisson on a mound.

In order to achieve this objective, the method of the present invention involves introducing large-sized rubble to form a rubble mound having a concave portion on the upper surface for forming a base, laying a concrete leak-proofing mat in the concave portion, and then placing a concrete leak-proof mat in the concave portion. Small rubble stones are placed on both sides of the recess where the mat has been laid to form a base, leaving a space in the center of the recess into which concrete will be press-filled, and then a caisson is placed on the base. The gist of this is to press-fill concrete into the above-mentioned space.

An example of carrying out the present invention will be described in detail below in accordance with the accompanying drawings.

First, as shown in Figure 1, the first step is to set the water depth H to about 5.
Large rubble stones 1, each weighing about 20 kg to 200 kg, are carried by a transport vessel 2 to a place where the caisson is to be installed in a deep sea area of about 0 m, and are evenly thrown into the sea so as not to be concentrated in one place.

By repeating this process many times, a rubble mound 3 having a trapezoidal cross section as shown in FIG. 2 is formed.

This rubble mound 3 has a thickness of about 24 m and a width of the upper surface of about 50 m.

A groove 4 is formed on the upper surface of the rubble mound 3, which is approximately 1 m lower than the installation surface, corresponding to the section where the caisson will be installed later.

Next, as shown in FIG. 3, the upper surface of the rubble mound 3 is compacted using a preloading caisson 5, and then a concrete leakage prevention mat 6 is laid on the upper surface of the groove 4, as shown in FIG.

Then, as shown in FIG.
Comparatively small pieces of rubble 7, each weighing about 30 kg, are thrown along both sides of the ground with a width of 5 m to 10 m to form a base 8, and a space S is formed between the rubble stones 7 thrown on both sides.

After that, the base surface 8 is leveled using a rubble leveling boat 9 or the like.

After the leveling work is completed, a super large RC caisson 10 is placed on the base surface 8 as shown in FIG.

The dimensions of this caisson 10 are width 35. Om, height 37,
The length is 30.0 m, and the weight is approximately 18,000 tons.

Once the caisson 10 is placed on the base surface in this way, the concrete 12 is press-filled into the space S through the appropriate holes drilled in the bottom surface of the caisson from the concrete plant ship 11, and the gaps between the small rubble stones 7 are filled. Inject mortar separately.

As a result, the small rubble stones 7 are firmly connected, and a stable base surface is formed.

As a final step, as shown in FIG. 7, a foot protection block 13 is planted at the base end of the caisson 10 installed on the rubble mound 3 to stabilize the installation of the caisson.

In this way, the installation of the caisson is completed.

As is clear from the above description, according to the method of the present invention, a recess is formed in the planned caisson installation section on the upper surface of a mound made of large rubble, a concrete leak-preventing mat is laid in this recess, and then a concrete leakage prevention mat is laid along both sides of the recess. Relatively small rubble is thrown in to form a base surface, and a space for filling with concrete is left in the middle of the recess.Then, after placing a caisson on the base surface, concrete is poured into the space. Since it is press-fitted, the leveling area of the base surface is extremely small, and since the small rubble 7 is used, leveling work can also be done by machine, making the entire caisson installation work very easy and easy even though the water depth is large. It has many advantages, such as being quick to carry out, and by interposing a concrete leak-proof mat, concrete will not leak from the recess, thus providing economical and stable support for the caisson.

[Brief explanation of drawings]

The drawings show an example of the implementation of the method of the present invention, and the first
The figure is a side view showing the process of forming a rubble mound.
Figure 2 is a side view showing the formed rubble mound, Figure 3 is a side view showing the method of compacting the rubble mound, Figure 4 is a side view showing the concrete leakage prevention mat, and Figure 5 is a side view of the base. FIG. 6 is a side view showing the installed caisson in cross section, and FIG. 7 is a side view showing the state after the installation is completed. 1... Large rubble, 3... Rubble mound, 4... Recess, 6... Concrete leakage prevention mat, 7...・Small rubble, 10...
...Caisson, S...A space into which concrete is press-filled.

Claims (1)

[Claims] 1. A process of throwing in large-sized rubble to form a rubble mound with a recess for forming a base on the top surface, a process of laying a concrete leak-proof mat in the recess, and a process of laying a concrete leak-proofing mat in the recess, and a process of placing large rubble on both sides of the recess where the mat is laid. A process of placing comparatively small rubble into the base to form a base and forming a space in the middle into which concrete will be press-filled, and placing a caisson on the base and pouring concrete into the space. A caisson installation method including a press-fit filling process.