JPH04166509A - Prevention of degradation of trench wall in artificial island - Google Patents

Abstract

PURPOSE:To prevent the degradation of trench wall by a method in which a blind-like sheathing panel is set on the back side of trench wall to be excavated ahead of filling work and buried to construct an artificial island, and a trench is excavated while supporting the soil pressure of the back side of trench wall by the sheathing panel. CONSTITUTION:A revetment 2 whose lower part is put into the bottom 1 under water and the upper part is projected from the surface of water is constructed on the peripheral edge of an artificial island to be constructed. Guide piles 3 are driven at a given interval into one or both sides of an underground wall to be constructed on the inside of the revetment 2 temporarily closed. The sheathing panel 5 is set between the piles 3, the inside of the revetment 2 is embedded to bury the piles 3 and the panel 5 to construct the island A. A guide wall 6 is constructed connectedly to the upper part of the panel 5 and a trench 7 for underground wall is excavated along the wall 6. In this case, the trench 7 is excavated to a given depth while filling it with a stabilization liquid 8, and a reinforcing bar cage is set in the trench 7. Concrete is then placed to construct the underground wall. The degradation of the trench wall can thus be effectively prevented at low cost by eliminating the need for improving the surrounding ground.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a technique for constructing an underground wall on an artificial island, and specifically relates to a method for preventing collapse of a trench wall.

<Conventional technology> When constructing an underground wall on an artificial island constructed by reclaiming land,
Because the ground on artificial islands is unstable, collapse of ditch walls (clump-like collapse, skin falling) is a problem.

Therefore, when constructing underground walls on artificial islands, the trench walls are stabilized by filling the trench with a stabilizing liquid with high specific gravity.

Furthermore, if the excavated ground is soft or there is a possibility of impact on nearby structures, the area around the ground where the underground wall is planned to be constructed may be improved and strengthened, or the back side of the trench wall to be excavated may be An auxiliary construction method is used to construct solidified walls and columnar walls.

<Problems to be Solved by the Invention> The conventional techniques for preventing the collapse of groove walls described above have the following problems.

<B> In the method of stabilizing trench walls with a stabilizing liquid, it is difficult to control the composition of the stabilizing liquid and the level of the stabilizing liquid depending on the excavated ground and water quality.

<Talking> Methods that use auxiliary construction methods have the problem of prolonging the construction period and increasing construction costs.

<C> As a method of preventing the collapse of the trench wall, it is possible to construct an artificial island by filling it with a hardening material such as premix.

However, during excavation, changes in the specific gravity of the stabilizing fluid and changes in fluid pressure occur in combination, which tends to cause cracks in the hardened material.

If this crack progresses, there is a risk that the trench wall will collapse due to soil clod sliding.

<Object of the present invention> The present invention was made to solve the above-mentioned problems, and its purpose is to prevent the collapse of the groove wall on an artificial island by a simple method. The purpose is to provide a method of prevention.

<Means for solving the problem> In other words, the present invention, in an artificial island constructed by filling the inside of a seawall, installs a layered earth retaining panel on the back side of the trench wall to be excavated prior to filling. , a ditch wall collapse on an artificial island characterized by constructing an artificial island by burying an earth retaining panel, and then excavating a trench close to the earth retaining panel while supporting the earth pressure on the back of the ditch wall with the earth retaining panel. This is a prevention method.

<Description of the present invention> The present invention will be described below with reference to the drawings.

<B> Seawall construction (Fig. 1) A seawall 2 will be constructed around the periphery of the artificial island to be constructed, with the lower part embedded in the water bed 1 and the upper part protruding above the water.

The seawall 2 may be made of steel or concrete, and its construction method is a known method.

<Entrance> Driving guide piles (Figure 1) Inside the temporarily closed seawall 2, guide piles 3 are driven at predetermined intervals on both sides or one side of the underground wall to be constructed.

<C> Installation of earth retaining panels (Figs. 1 to 3) Next, earth retaining panels 5 are installed between adjacent guide piles 3.3.

FIG. 2 shows an example of the retaining panel 5.

The retaining panel 5 is a member formed in a lattice shape by intersecting a plurality of vertical ropes 52 such as flexible tie lobes between horizontal strips 51 arranged in parallel, and the upper and lower ends of each vertical rope 52 are made of H steel or the like. It is connected to horizontal beams 53 and 54.

To install the retaining panel 5 on the guide pile 3, the upper horizontal beam 53 is hooked to the upper projection of the guide pile 3 and suspended, and each horizontal beam 53, 54 and the horizontal reinforcement 51 are fixed to the guide pile 3. .

In addition, as shown in FIG. 3, each earth retaining panel 5 is connected to a guide pile 3.
When installing between the horizontal strips 51, it is preferable to wrap the ends of each horizontal strip 51 extending in the horizontal direction.

<2> Filling (Fig. 4) After placing the retaining panel 5 on the back side of the trench wall to be excavated,
Build artificial island A by filling it inside seawall 2.

As a result, the guide pile 3 and earth retaining panel 5 are buried.

For example, a hardening material 4 such as a premix is used as the filling material, and general earth and sand 41 is used for the upper part of the earth retaining panel 5.

There are also cases where the artificial island A is filled with only general earth and sand.

In addition, 6 in the figure is a guide wall constructed continuously on the upper part of the earth retaining panel 5.

<E> Excavation of trench for underground wall (Fig. 5) When artificial island A is completed, trench 7 for underground wall is excavated along guide wall 6.

At this time, the groove 7 of a predetermined depth is excavated while being filled with the stabilizing liquid 8.

The stabilizing liquid 8 pressurizes the groove walls to suppress collapse of the groove walls.

At the same time, the earth retaining panel 5 supports the hardening material 4 or the general earth and sand on the back side, and effectively prevents the trench wall from collapsing.

In this way, the layered earth retaining panel 5 and the stabilizing liquid 8 can effectively prevent the groove 7 from collapsing due to the sliding of the clod.

<<>> Construction of underground wall (Fig. 6) After completing the excavation of trench 7, erect a reinforcing bar cage in trench 7,
Construct underground wall B by pouring concrete.

<Effects of the Present Invention> Since the present invention is as described above, the following effects can be obtained.

<B> The layered earth retaining panel installed on the back side of the trench wall prior to trench excavation can effectively prevent the trench wall from collapsing.

Therefore, there is no need to strictly control the composition and liquid level of the stabilizing liquid.

<Exposure> It is no longer necessary to improve the surrounding ground using auxiliary construction methods as in the past, and construction costs can be reduced.

<C> Because the earth retaining panels are layered, they are easy to handle during installation.

(2) Since the horizontal beams above and below the earth retaining panel function as vertical tensile resistance materials, a large earth pressure suppression effect can be expected.

<E> By wrapping the horizontal stripes, horizontal continuity can be given to the earth retaining panel.

〈〈〉 It can be constructed even if there are nearby structures or on soft ground.

[Brief explanation of the drawing]

Figure 1: Explanatory diagram of the construction method up to the installation of earth retaining panels Figure 2: Perspective view of earth retaining panel Figure 3: Cross-sectional view of ■-■ in Figure 1 Figure 4: Explanatory diagram when filling the artificial island Figure 5: Explanatory diagram for trench excavation Figure 6: Explanatory diagram of completed underground wall Figure 1 ■− Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] (1) For artificial islands constructed by filling the inside of the seawall, an earth retaining panel is installed on the back side of the trench wall to be excavated prior to filling, and the earth retaining panel is buried to construct the artificial island. A method for preventing the collapse of a trench wall on an artificial island, characterized by the step of excavating a trench close to the earth retaining panel while supporting the earth pressure on the back side of the trench wall with the earth retaining panel.