JPH09316870A - Sheet pile as measure against liquefaction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet pile for preventing liquefaction of the ground by an earthquake or the like, and restricting collapse of a retaining wall, or slide motion of the ground. SOLUTION: On an outer circumferential surface of a steel pipe 2 of a steel pipe sheet pile 1, natural grain material such as gravel, or waste material of slag, resin, etc., granulated, is applied using binder such as cement material or binding agent, and a porous water-permeable layer 2 is formed to a desired thickness. The steel pipe sheet pile 1 is constructed with an upper part of the water-permeable layer 2 in contact with a gravel mat constructed on a bottom part or the like in a structure, thereby excessive pore water is discharged from the water-permeable layer 2 through the gravel mat onto the ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquefaction countermeasure sheet pile which prevents liquefaction due to vibration external force such as an earthquake on the ground which is likely to be liquefied and which can restrain and stabilize the ground.

[0002]

2. Description of the Related Art As a countermeasure against ground liquefaction, a method of discharging excess pore water in the ground during an earthquake is used. This drainage method is applicable to the gravel drain method, which aims to increase the shearing strength of the ground and increase the drainage effect by installing a large number of permeable gravel (gravel) columns in soft ground. A method of pumping groundwater, in which the ground is surrounded by a water blocking wall that reaches an impermeable layer, and groundwater is pumped from the inside to keep the groundwater level low at all times, or
A method of using a hollow perforated pile (see Japanese Patent Laid-Open No. 61-146910) in which a large number of holes are formed in the pile and a filter having water permeability is provided in the hole portion to prevent sand from entering is there.

[0003]

The above-mentioned gravel drain
The construction method requires construction of support piles for the structure separately, which makes the construction cost more expensive, and the method of pumping up groundwater is costly for operation of pumps, maintenance, and treatment of pumped water. In addition, there are problems such as depletion of surrounding wells and land subsidence. In addition, the hollow perforated pile has a drawback that the strength of the pile is reduced because a large number of holes are formed in the pile main body.

[0004] By the way, sheet piles are installed as a retaining wall for seawalls, rivers, etc., embankments, and embankments. In such a case, if the ground liquefies during an earthquake, the sheet pile will lose its supporting function. Therefore, the present invention, instead of the conventional construction method which requires a large amount of money, by providing a drainage function in the portion of the sheet pile that contacts the liquefied ground, the supporting function of the sheet pile is ensured even during an earthquake, The strength and rigidity of the ground itself are used to restrain the ground and exert a stabilizing effect.

[0005]

To achieve the above object, the structure of the present invention will be described with reference to the drawings corresponding to the embodiments. A liquefaction-preventing steel pipe sheet pile corresponding to claim 1 is a steel pipe 2. In the steel pipe sheet pile 1 formed by projecting the joints 3, 3 along the outer longitudinal direction of the, a natural granular material such as gravel or a granular material made of waste material such as slag or resin is cemented on the outer periphery of the steel pipe 2. It is characterized in that a porous water permeable layer 4 is formed by applying a binder such as a system material or an adhesive.

The liquefaction-preventing steel sheet pile according to claim 2 is characterized in that, on one side or both sides of the outer side surface of the steel sheet pile 1, a natural granular material such as gravel or a granular material made of waste material such as slag or resin is used. It is characterized in that a porous water permeable layer 4 is formed by applying a binder such as a cement material or an adhesive.

[0007]

1 and 2 show an embodiment of the steel pipe sheet pile of the present invention, and FIGS. 5 and 6 show other embodiments thereof. Further, FIG. 7 shows an embodiment of the steel sheet pile of the present invention, and FIG. 9 shows another embodiment thereof.

First, the steel pipe sheet pile will be described. Figure 1,
In FIG. 2, reference numeral 1 is a steel pipe sheet pile, and as is well known in the art, a C extending outside the steel pipe 2 along the longitudinal direction of the steel pipe 2.
A pair of joints of shapes and the like are provided so as to face each other.

Then, in the steel pipe sheet pile 1, a half circumference portion between the joints 3 and 3 on the outer circumference of a portion in contact with the sandy soil layer which may be liquefied due to an earthquake or the like has a required grain size. A porous water-permeable layer 4 having a required thickness is formed by mixing a granular material with a binder (connecting material) and applying the mixture. Further, a protective body 6 surrounding the lower outer periphery of the water permeable layer 4 is fixed to the steel pipe 2 below the water permeable layer 4.

As the granular material, for example, a natural material such as gravel or a granular material such as granulated slag, blast furnace slag, concrete debris, FRP debris, etc. is used. It is preferable that the particle size is about 5 to 10 times the particle size of the sample collected from the ground. As the binder, cement-based materials such as richly mixed cement milk, mortar and concrete, or acrylic-based, epokin-based and other adhesives and water-permeable asphalt can be used.

The thickness of the water permeable layer 4 is preferably about 5 to 10 cm, but it is determined in consideration of the soil quality of the ground, the groundwater level, the design seismic intensity and the importance of the structure. Further, the water permeable layer 4 is formed by carefully kneading the granular material and the binder and spraying a paste-like material or molding with a frame.

FIG. 3 shows an example in which the steel pipe sheet pile 1 having the above structure is used as a revetment wall A for a sea, a river or the like. In this case, in the steel pipe sheet piles 1 and 1, the side provided with the permeable layer 4 faces the ground, and the side not provided with the permeable layer faces the sea or river side,
The lower part is embedded in the support layer 13 below the seabed or riverbed, and is connected to each other by the joints 3, 3. A curb stone structure 10 is provided on the upper ends of the steel pipe sheet piles 1, 1, and the water permeable layers 4, 4 are joined to a gravel mat 11 installed from the bottom of the curb stone structure 10 to the ground, and the water permeable layer 4 is formed. It is designed to come into contact with the sandy soil layer 12 for almost the entire length.

Excessive pore water generated in the sandy soil layer 12 at the time of earthquake should invade the permeable layer 4 and rise, and flow out to the ground via the gravel mat 11, and the excess pore water pressure should be dissipated to the ground. become. The steel pipe sheet pile of the present embodiment can be widely applied to a soil retaining wall or the like in which one side is in contact with the ground and the other side is excavated.

FIG. 5 shows another embodiment of the steel pipe sheet pile 1. In this embodiment, the outer surface of the water permeable layer 4 described above is covered with a clogging preventing net 5 made of polyester or the like.

FIG. 6 shows still another embodiment of the steel pipe sheet pile 1. In this embodiment, the water permeable layer 4 is formed on the other half of the steel pipe 2 with the joints 3 interposed therebetween in the same manner as in the previous embodiment. Also in this embodiment, as in the embodiment of FIG. 5, the water-permeable layers 4, 4
The outer surface of the can be covered with a clogging prevention net. In this embodiment, the ground wall that restrains the ground and
It can be widely applied to embankment restraint walls as shown in.

Next, the steel sheet pile 7 will be described. In FIG. 7, reference numeral 8 denotes a main body portion of the steel sheet pile 7, which is bent and formed into a required shape, and joint portions 9 and 9 for connection are provided on both side ends thereof. Then, on one side surface of the main body portion 8, as in the embodiment of FIG. 1, the water permeable layer 4 is deposited and formed to the required thickness over the range of the required length of the main body portion 8, and the lower end portion thereof is formed. Is surrounded by a protective body 6. As shown in FIG. 8, the steel sheet pile 7 of this embodiment is installed as a soil retaining wall or the like by aligning the side provided with the water permeable layer 4 with the side in contact with the ground.

Further, as shown in FIG. 9, the steel sheet pile 7 can be provided not only on one side of the main body 8 but also on both sides thereof,
Further, the outer surface of each of the water permeable layers 4 can be covered with the clogging prevention net 5 as in the embodiment of FIG. If the steel sheet pile 7 of this embodiment is used as an earth retaining wall for the embankment 14 as shown in FIG. 10, for example, excess pore water can be discharged due to an earthquake inside or outside the embankment area, ground restraint, stability, and embankment 14 It can function enough to prevent collapse. Also,
Instead of the steel sheet pile 7 of FIG. 10, the steel pipe sheet pile 1 of FIG. 6 may be used.

[0018]

As explained above, according to the liquefaction countermeasure sheet pile of the present invention, when excessive pore water pressure is generated during an earthquake,
The water in the ground will be discharged to the ground through the gravel mat from the water permeable layer formed on the outer peripheral surface of the steel pipe sheet pile or the side surface of the steel sheet pile, and the excess pore water pressure can be quickly dissipated. Can be prevented. Moreover, since these sheet piles have a water-permeable layer formed on the outside of the steel pipe or body, they do not reduce the yield strength of the sheet piles, and other measures against liquefaction such as excess pore water discharge means. There is no need to carry out, and the cost can be greatly reduced.

When the sheet pile of the present invention is used, it depends on the type of sheet pile wall such as revetment wall and earth retaining wall to which it is applied, the material characteristics and liquefaction strength of the ground, the conditions of seismic motion, the sheet pile size and the material of the water permeable layer. Although the effect of reducing the excess pore water pressure is different, for example, if the excess pore water pressure can be reduced to a value allowed in the design, it becomes possible to design the sheet pile wall without considering the liquefaction of the ground. As a result, it becomes possible to reduce the sheet thickness of the sheet pile and simplify the shape. Furthermore, since waste materials such as slag and resin can be used as the material of the water permeable layer, it is possible to provide a sheet pile for liquefaction measures at low cost while considering the environment.

[Brief description of drawings]

FIG. 1 is a partially cut side view showing an embodiment of the steel pipe sheet pile of the present invention.

FIG. 2 is a plan sectional view of the same.

FIG. 3 is a schematic vertical sectional view of the same use example.

FIG. 4 is a plan sectional view of the same.

FIG. 5 is a partially cut side view showing another embodiment of the steel pipe sheet pile of the present invention.

FIG. 6 is a partially cut side view showing still another embodiment.

FIG. 7 is a perspective view showing an embodiment of the steel sheet pile of the present invention.

FIG. 8 is a plan view showing an example of connection of the steel sheet piles.

FIG. 9 is a plan view showing another embodiment of the steel sheet pile.

FIG. 10 is a schematic vertical sectional view showing an example of use of the steel sheet pile.

[Explanation of symbols]

 1 Steel Pipe Sheet Pile 2 Steel Pipe 3 Joint 4 Permeable Layer 5 Clog Prevention Net 6 Protective Body 7 Steel Sheet Pile 8 Main Body 9 Joint 10 Curbstone Structure 11 Gravel Mat 12 Sandy Soil Layer 13 Support Layer 14 Embankment

Claims (2)

[Claims] 1. A steel pipe sheet pile having a joint projecting along the outer longitudinal direction of the steel pipe, wherein a natural granular material such as gravel or a granular material made of waste material such as slag or resin is provided on the outer periphery of the steel pipe. A liquefaction-resistant steel pipe sheet pile characterized by being formed by using a binder such as a cement-based material or an adhesive to form a porous water-permeable layer. 2. A natural particulate material such as gravel or a granular material such as waste material such as slag or resin is adhered to one side or both sides of an outer surface of a steel sheet pile by using a binder such as a cement material or an adhesive. The liquefaction-preventing steel sheet pile has a porous water-permeable layer.