JPH0325564B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a construction method for artificial islands, quays, bridge foundations, and other large offshore structures.

[Conventional technology]

When constructing such large offshore structures that utilize underground continuous walls, it is customary to build islands using double-walled structures such as sheet piles or steel pipe sheet piles. However, this construction method requires large-scale island construction, and the quality of the filling soil also poses problems.

Therefore, instead of reclamation of Tsukishima, which is costly and time-consuming, a construction method has been proposed in which the entire Tsukishima is fixed using underwater soil cement, which is made from a mixture of earth, sand, and cement, and can be cast underwater. ing. FIG. 11 shows an example of this, and in the figure, 1 is a temporary pier installed on the sea. Using this pier 1 as a foothold, steel sheet piles 2 such as sheet piles
A single closing is performed, and the inside of the steel sheet pile 2 is hardened with the underwater soil cement 3. Next, the inside of the built-up island 5 made of the underwater soil cement 3 is excavated using a super-large excavator 4 capable of deep excavation, and an underground continuous wall 6 is constructed.

[Problem that the invention seeks to solve]

However, with the construction method shown in Figure 11,
Due to excavation and other technical issues, the underground continuous wall 6 must be constructed at a location slightly away from the steel sheet pile 2 and inward from the end of the island 5.

As a result, it is necessary to remove the construction island materials outside the underground continuous wall 6, which is troublesome and
During this removal, there is a risk that the materials from the construction island will flow into the sea and cause marine pollution. In addition, unnecessary parts are also built up, which results in a lot of waste.

The purpose of the present invention is to eliminate the disadvantages of the conventional example,
To provide a construction method for offshore structures that requires a simple single-clamp construction method, does not require the removal of the outer part of the continuous wall, and requires only the minimum required area and volume for the built island, which can streamline construction. be.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention has a steel sheet pile having a large section modulus and having at least one side joined to form a continuous plane. The gist is to fill the area with earth and sand or soil concrete to build an island, then excavate the edge of the island along the plane of the steel sheet pile to create a concrete underground continuous wall, and then remove the steel sheet pile, etc. It is something.

[Effect]

According to the present invention, since the joint surface of the steel sheet pile with the Tsukishima is a continuous plane, it is possible to excavate the inside from this part and construct the underground continuous wall so as to join to the sheet pile. Therefore, if the steel sheet piles are removed after the Tsukishima is completed, the underground continuous wall will be located at the outermost part, and there will be no need to remove unnecessary materials.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figures 1 to 4 are longitudinal sectional side views showing each step of the construction method of a marine structure according to the present invention, and the same components as in Figure 11 showing the conventional example are given the same reference numbers. .

As shown in Fig. 1, a temporary pier 1 is installed as a foothold on the sea in advance. On the side of this temporary pier 1, rulers 7 made of two steel materials such as H-beams arranged in parallel at small intervals are placed vertically. Provide appropriate steps in the direction. Then, the steel sheet piles 8 are launched vertically from above the temporary pier 1 via the ruler 7 until they reach the required depth of the seabed ground.

The steel sheet pile 8 has a large section modulus, that is, a large cross-sectional shape so that only a single cofferdam is required for construction, and at least the joint and one side are aligned in a straight line, so that a continuous plane 10 can be formed in the joined state.

As an example, as shown in FIG.
A special shaped sheet pile 8a is used, in which the joints of two molded sheet piles are welded to each other, and the opening of the two shaped sheet piles is rigidly connected to each other, and the opening of the cross-sectional shape is closed in plan by welding a steel plate 9.

When such special sheet piles 8a are driven so as to be successively joined between the rulers 7 as shown in FIG. 5, one side surface of the side on which the island is to be built is formed as a continuous plane 10 by the steel plate 9.

FIG. 8 is a plan view showing the entire situation.
In addition, regarding the corner part, as shown in Figure 9,
The steel pipe 12 may be disposed as a retainer via an auxiliary member 11 such as a shaped steel.

Furthermore, as another embodiment, as shown in FIG. 7, if box-shaped sheet piles 8b are used to join them in a ladder shape, there is no need to cover them with steel plates 9, and a continuous plane 10 is created. can get. The corner portion in this case becomes as shown in FIG.

Once the steel sheet piles 8 are driven by the sheet piles 8a or 8b, one of the steel members of the ruler 7 is removed and the inside of the steel sheet piles 8 closed off by the steel sheet piles 8 is filled with earth and sand, as shown in FIG. The island 5 is created by hardening with soil concrete or underwater soil concrete 13, which is a mixture of concrete.
If only earth and sand is used, it may be necessary to drain water using a well point, etc.

Soil concrete may be used, but underwater soil concrete is suitable for reliability. The underwater soil concrete 13 is obtained by kneading earth and sand and underwater hardening concrete, but this concrete is made of an underwater inseparable miscible material that gives consistency to the concrete and prevents separation of the materials in water. (or segregation reducing agent) is used. The main components of the admixture include water-soluble polymeric ether, water-soluble cellulose ether, water-soluble acrylic polymer compound, etc. as thickeners, and antifoaming agents, hardening accelerators, and fluidizing agents. Add as appropriate.

Next, as shown in Fig. 3, a long hole is excavated at the end of Tsukishima 5 using the ultra-large excavator 4 along the continuous plane 10 of the steel sheet pile 8, a reinforcing bar cage is set in this excavation hole, and concrete is poured. Then, a continuous underground wall 6 is created.
In this case, the continuous plane 10 of the steel sheet pile 8 serves as a formwork when constructing the continuous wall 6.

After the underground continuous wall 6 is completed, the steel sheet pile 8 is removed, but it can be easily removed if a release agent is applied to the continuous plane 10 in advance.

〔Effect of the invention〕

As described above, the construction method of the offshore structure of the present invention allows the underground continuous wall to be constructed at the outermost end of the rocky island when simple construction is performed using a single wall instead of large-scale land reclamation work. Removal of the outer construction island materials is also unnecessary, and the number of steps can be reduced. In addition, the island can be built with the minimum necessary area and volume, making it possible to rationalize construction and reduce costs.

[Brief explanation of drawings]

FIGS. 1 to 4 are longitudinal side views showing each step of the construction method for offshore structures of the present invention, FIG. 5 is a plan view of the steel sheet pile portion, and FIG. 6 is a plan view showing a single steel sheet pile.
Fig. 7 is a plan view showing another example of the steel sheet pile, Fig. 8 is a plan view showing the overall assembled state, Fig. 9 is a plan view of the corner portion when the steel sheet pile shown in Fig. 5 is used, and Fig. 10 is a plan view showing another example of the steel sheet pile.
The figure is a plan view of a corner portion in the case of using steel sheet piles as shown in Fig. 7, and Fig. 11 is a vertical sectional side view showing a conventional example. 1... Temporary pier, 2... Steel sheet pile, 3... Underwater soil cement, 4... Excavator, 5... Tsukishima, 6...
Underground continuous wall, 7... Ruler, 8... Steel sheet pile, 8a,
8b... Sheet pile, 9... Steel plate, 10
... Continuous plane, 11 ... Auxiliary member, 12 ... Steel pipe, 13 ... Underwater soil concrete.

Claims (1)

[Claims] 1. A steel sheet pile with a large section modulus and with at least one side connected to form a continuous plane is poured over the temporary pier, and the area surrounded by the plane of the steel sheet pile is filled with earth and sand or soil concrete. A construction method for a marine structure characterized by constructing an island, then excavating the end of the island along the plane of the steel sheet pile to create a concrete underground continuous wall, and then removing the steel sheet pile, etc.