JPS61134433A - Method of building revetment - Google Patents

Abstract

PURPOSE:To enable reduction of the back pressure of a banking layer, by a method wherein a water permeable sheet is laid in a range of from the front part of the bottom part of a caisson to the upper part of the back, and the water permeable sheet, having the one end secured to the caisson, is developed in a back-filling layer to form a baning layer. CONSTITUTION:Cobble-stone 4 is banked on a replacement laeyr 3, in which a sea bottom ground 3 is replaced with cobble-stone and the like, to form a sink bed 5, and a water permeable materail 11 is laid and extended in a range of from a front 22 of a caisson 2, intended to be sunk, to a portion under a banking layer. The caisson 2 is sunk on a sink bed 5, the interior of the caisson is filled with a fill 6, and an upper surface part 23 is blocekd up. The water permeable sheet 1, the one end iof which is secured to a back 21 of the caisson 2, is about horizontaly extended, and banking layers G1-Gn are formed between the sheets 1. Further, the water permeable sheet 11 is vertically laid to the back 21 of the caisson 2. This enables decerase of an eaerth pressure exerted on the back of the caisson.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a seawall construction method in which earth and sand is backfilled on the back side of concrete retaining walls, caissons, etc. that are in contact with water bodies.

[B] Prior art] The moisture content of the soil on the back side of a concrete structure greatly affects the design and stability of the seawall structure.

Problems to be Solved by the Present Invention Conventional sea walls have the following problems.

(1) When the water content in the soil increases due to waves or rainfall, the pore water pressure increases and the shear strength of the soil decreases.

Therefore, the pressure acting on the back side of a concrete structure backfilled with earth and sand increases rapidly.

(2) In particular, if such a high water content state is subjected to earthquakes or vibrations from moving vehicles, the earth and sand will liquefy and the concrete structure will deform and there is a very high risk of it falling over.

(3) If the shear strength of the back earth and sand is designed to be small for stabilization, the revetment structure will become large and uneconomical.

The present invention was made to solve these problems, and an object of the present invention is to provide a seawall construction method using a small and stable structure.

[Means for Solving the Problems] The present invention provides a method for constructing a seawall by filling the back surface of a concrete structure with earth and sand. Connect the sheet group, deploy this sheet group almost horizontally in the backfill soil, and connect the upper and lower developed sheets with a water-permeable material to connect the sheet group to the water area in front of the concrete structure in terms of water permeability. .

The invention also relates to technical means for solving the above-mentioned problems by maintaining a good pressure balance between the front and back surfaces of a concrete structure.

[Second] Example Hereinafter, a method of constructing a seawall in which a concrete structure (caisson) is deposited to form a seawall, which is an example of the present invention, will be described with reference to the drawings. (Fig. 1) (1) Water-permeable sheet used in the present invention The water-permeable sheet 1 is a nonwoven fabric or the like formed by three-dimensionally intertwining continuous long fibers.

This water-permeable sheet 1 has corrosion resistance and moderate strength,
Furthermore, if the material has the function of collecting and draining soil moisture when buried underground, it can be a fibrous material whose main component is thermoplastic fibers such as polyamide, polyethylene, polypropylene, polystyrene, or a network thereof. Alternatively, it is of course possible to use a string-like body or a composite thereof.

(2) Attaching the water-permeable sheets One end of the water-permeable sheets 1 is attached in advance to the back of the concrete structure (caisson) 2 at equal intervals in the vertical direction and integrated.

Furthermore, a connecting water-permeable sheet 11, which is a water-permeable material, is attached to the back of the concrete structure (caisson) 2 in a longitudinal direction connected to the sheet group 1.

The same material as the water permeable sheet 1 can be used for this water permeable material.

This communication water-permeable sheet 11 is connected to each water-permeable sheet 1, and is exposed to the front surface 22 side through the bottom surface of the concrete structure (caisson) 2, for example, for the purpose of communicating with the water area in contact with the seawall. It is a water permeable member.

(3) Formation of sunken bed (Fig. 3) A sunken bed 5 is formed by heaping up chestnut stone 4 on top of the replacement layer 3 which has been replaced with rubble or the like in the underwater ground where the concrete structure (caisson) 2 is to be installed.

(4) Sinking the concrete structure (caisson) The concrete structure (caisson) 2 is towed or suspended to the sinking position.

Then, a concrete structure (caisson) 2 is deposited by a known method.

At this time, a permeable material 11 is placed between the bottom of the concrete structure (caisson) 2 and the submerged floor 5.
Caisson) 2 is exposed on the front 22 side.

Next, after filling the concrete structure (caisson) 2 with filler 6, the upper surface portion 23 is closed.

(5) Filling with backfill earth and sand [Construction of embankment layer] Embankment layers are sequentially constructed as G1, G2, G3, etc. on the foundation ground G on the back 21 side of the concrete structure (caisson) 2.

[Laying the permeable sheet] The embankment layers are constructed in sequence (at this time, between each embankment layer, the permeable sheet 1 with one end attached to the back surface 21 of the concrete structure (caisson) 2 is placed in a nearly horizontal direction. to intervene.

That is, after laying the water-permeable sheet 1 on the upper surface of the embankment layer G1, earth and sand as a backfilling material is carried on the water-permeable sheet 1 to form the embankment layer G2.

When the embankment layer G2 is completed, a new water-permeable sheet 1, which has been rolled up in advance, for example, is laid on top of the embankment layer G2, and embankment is performed to form an embankment layer G3. (Fig. 2) As a result, the permeable sheets 1 buried between each embankment layer Gn are connected as a waterway by the permeable material 11 and have continuity.

One of the features of the present invention is to provide water permeability between the backfill earth and sand and the water area side by guiding one end of the continuous water permeable sheet 1 to the water area side via the water permeable material 11.

Therefore, in order to connect the backfill earth and sand with the water area, for example, a groove, pipe, or permeable strip may be installed to penetrate the bottom or middle part of the concrete structure (caisson) 2, and a permeable sheet may be installed. 1 and the connecting water-permeable sheet 11 so that water can pass therethrough, or the water-permeable sheet 1 can be guided to the water body side.

[E] Effect As explained above, in the present invention, a continuous water-permeable sheet is buried in layers in the earth and sand filled at the back of a concrete structure, and one end of this sheet is connected to a water area in front of the concrete structure. By providing guidance, the following effects can be expected.

(1) In the case of the present invention, one end of the sheet group buried in the soil is fixed to a concrete structure, and the water-permeable sheet actively collects and drains water from the soil, so the soil The shear resistance and frictional resistance of

Therefore, the concrete structure acts as an integral block with the earth and sand behind it, and has a strong resistance against the earth and sand of the rear embankment.

Therefore, the weight and wall thickness of the concrete structure can be significantly reduced, making it economical.

(2) By laying a group of permeable sheets in the backfilling soil, excess pore water pressure in the backfilling soil can be quickly dissipated.

Therefore, it is possible to prevent a decrease in the shear strength of the earth and sand, to reduce the amount of dirt, and to prevent the liquefaction of the earth and sand, thereby suppressing the movement of the concrete structure.

As a result, the stability of the seawall is significantly improved.

(3) Water pressure acting on the front and back surfaces of a concrete structure is canceled out by the water-permeable sheet.

Therefore, the pressure that acts on the concrete structure is calculated to be only that of the Tonosho, and can be dealt with with a relatively light structure.

Furthermore, the movement of the concrete structure toward the coast can be easily stopped by the frictional resistance between the sheet and the earth and sand behind it.

(4) By laying multiple layers of water-permeable sheets with drainage properties in the backfilling soil, it is possible to promote the settling of the backfilling soil and prevent uneven settlement after completion.

[Brief explanation of the drawing]

Claims (1)

[Claims] In bank protection construction in which the back of a concrete structure is filled with earth and sand, a plurality of water-permeable sheets are connected at one end to the back of the concrete structure, and this group of sheets is buried in the back. This is a seawall construction method that is developed almost horizontally within the returned soil, and the upper and lower developed sheets are connected using a water-permeable material to connect the sheet group to the water area in front of the concrete structure in terms of water permeability.