JPS6322916A - Construction of continuous underground wall in artificial islet - Google Patents

Abstract

PURPOSE:To maintain reinforcing effects by tie rods by method in which tie rods inserted into guide wall on the top end of an excavated trench and the sheath pipe of sheet pile are temporarily pulled out, underground walls are constructed, and the sheet piles are connected. CONSTITUTION:A tie rod 9 is thrust through sheet piles 1 and sheath pipes 6 and 7 pierced the lower part of a guide wall 5 and the sheet piles 1 set in an artificial islet 3 partitioned by the steel tubular sheet piles 1. The tie rod 9 is fixed with nuts 9a, and the tie rod 9 in the preceding construction section is pulled out. The preceding trench 11 is excavated while filling it with mud water under the guidance of the wall 5, a reinforcing bar cage is set in the trench 11, and concrete is placed. The tie rod 9 is again set to construct the preceding panel 12, and by repeating the same processes, the following panels are connected to the panel 12. An underground continuous wall can thus be constructed in the minimum area of the islet.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of constructing a continuous underground wall on an artificial island.

(Conventional technology) Underwater construction of continuous underground walls generally involves constructing an artificial island by pouring earth and sand into a cofferdam using steel pipe sheet piles, etc., and then installing reinforcing bars in an excavated trench inside the island. The construction and
This is done by repeating the process of placing concrete.

(Problems to be solved by the invention) Since artificial islands are frequently subjected to internal earth pressure, hydrostatic pressure, and dynamic pressure such as waves and water currents, it is necessary to connect and reinforce the sheet piles with tie rods.

Therefore, these tie rods become an obstacle when excavating an excavation trench or erecting reinforcing bars.

In other words, since the cofferdam is formed along the construction direction of the underground wall, the tie rod is necessarily perpendicular to the top of the excavated trench.

In addition, for artificial islands with relatively large areas, obstructions caused by tie rods can be eliminated by double closing.

However, double closing is expensive and is limited to deep-depth, large-area construction.

Furthermore, if the tie rods at the construction location of the underground wall are removed, the reinforcing effect will be completely lost.

This invention solves the above problems, and aims to construct an underground wall without removing the tie rods that intersect with the underground wall.

(Means for Solving the Problems) In order to solve the above object, the present invention divides a water area with a single cofferdam, constructs an artificial island by pouring earth and sand into the cofferdam, and reinforcing the artificial island by connecting them with tie rods, and then forming an excavation groove in the artificial island,
In the construction method of constructing a continuous underground wall by pouring concrete into the excavated trench, a sheath pipe aligned on the same straight line as a guide wall formed at the top of the excavated trench and a tie rod insertion position of the cofferdam. is provided in advance, and during construction of the underground wall, the tie rod is temporarily removed from the sheath pipe, and after construction, the tie rod is connected again through the sheath pipe between the cofferdams.

(Function) According to the construction method with the above configuration, it is only necessary to pull out the corresponding tie rod for each section of the underground wall and reload it after the construction is completed, so the construction can be carried out without losing the reinforcing effect of the tie rod. Can be done.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings.

FIGS. 1(a) to (f) are plan views showing the construction method of the present invention, and FIGS. 2(a) to (f) are plan views of the same location.

In Figure (a), numeral 1 is a pair of steel pipe sheet piles driven into the seabed. The steel pipe sheet piles 1 close off the sea area E, and as shown in Figure (b), there is a self-hardening stabilizer, soil cement, or The construction of the artificial island 3 is completed in a state where the earth pressure acting on the steel pipe sheet pile 1 is reduced by introducing filling soil 2 such as poorly mixed mortar.

This artificial island 3 is formed into an elongated shape along the construction direction of the continuous underground wall to be obtained, and a workbench 4 is constructed on the negative side thereof.

After the construction of the island is completed, a pair of guide walls 5, which will be described later, border the top of the excavated trench, are laid facing each other on the upper surface of the filling earth and sand 2 inside the sheet pile 1, as shown in FIG. 1C.

As shown in an enlarged view in FIG. 3, sheath tubes 6 are embedded in advance in the lower part of the guide wall 5 at appropriate intervals and perpendicular to the longitudinal direction. Also, the sheath pipe 6 is also included in the sheet pile 1.
The sheath tubes 7 are arranged penetrating the inside and outside at the same pitch. When installing the guide wall 5, the sheath tubes 6.7 are arranged on the same straight line.

Thereafter, as shown in FIG. 1.2(d), the sheet piles 8 are placed on the outside of the guide wall 5, and then the sheet piles 1. A tie rod 9 is inserted into the sheet pile 1 through the sheath tubes 6 and 7 of the guide wall 5, and fixed with a nut 9a (see FIG. 3). The artificial island 3 is thereby sufficiently reinforced.

After the above preparatory work, the continuous underground wall construction work will be carried out.

In this work order, first, as shown in Fig. 1.2(e), the preceding work section A is positioned, and the tie rod 9 perpendicular to the work section A is moved to the riverbed. After that, using the guide wall 5 as a guide, the preceding excavation trench 11 is excavated while filling with muddy water 10, and the amount of reinforcing bars is erected and concrete is placed.As shown in FIG. The intermediate continuous wall or preceding panel 12 is completed.

The above-mentioned series of operations are performed by an excavator, a crane, a concrete pouring machine, etc. installed on the work construction table 4.

After the construction of the preceding panel 12 is completed, the tie rod 9 that has been left in the riverbed is loaded again. This eliminates the vulnerability of the preceding construction section A.

Next, as shown in Figure (f), the construction of the succeeding work area B is carried out adjacent to the preceding work area A, but this work area B also uses the same tie rod 9 and excavated groove 11 as the preceding work area A. Excavation, erection of reinforcing bars, and concrete placement are performed, and the trailing panel 14 is succeeded to the leading panel 12. After completing the construction of the trailing panel 14, the tie rod 9 is loaded again.

After that, the construction of the continuous underground wall is completed by repeating the work one after another in the same cycle.

(Effects of the Invention) As explained in the embodiments above, according to the construction method of the present invention, the tie rods can be used to reinforce the artificial island by pulling out the tie rods for each construction section and reloading them after the completion of construction. will not be damaged. In addition, when constructing an underground continuous wall, only the minimum construction area and cut-off intervals are required, and the construction cost is also low.

[Brief explanation of the drawing]

Figures 1 (a) to (f) are plan views showing the construction method of the present invention, Figures 2 (a) to (f) are sectional views of the same, and Figure 3 shows details of the state of connection of the tie rod to the sheath pipe. FIG. 1...Steel pipe sheet pile 2...Filled earth and sand 3...Artificial island 5...Guide wall 6.7...Sheath pipe 9...・・・
Tie rod 12... Leading panel (underground wall) 14... Trailing panel (underground wall) Patent applicant Obayashi Corporation Agent
Person Patent Attorney - Color Ken Shaft Circumference
Patent Attorney Masaru Matsumoto Kazuko Figure 1 (a) Figure 1 (C) (d) Figure 1 (e) (f) Figure 2 (a) Figure 2 (b) Figure 2 (C) 2 Figure (d) Figure 2 (e)

Claims (1)

[Claims] (1) Divide the water area with a single cofferdam, construct an artificial island by pouring earth and sand into the cofferdam, connect the coffers with tie rods to reinforce the artificial island, and then In a construction method in which an excavated groove is formed in an artificial island and concrete is poured into the excavated groove to construct a continuous underground wall, the guide wall formed at the top of the excavated groove and the tie rod insertion position of the cofferdam. A sheath pipe arranged in the same straight line is provided in advance in the underground wall, the tie rod is temporarily removed from the sheath pipe during construction of the underground wall, and after construction, the tie rod is connected again through the sheath pipe between the cofferdams. Construction method for continuous underground walls on artificial islands.