JP2000096596A - Floating prevention structure of buried construction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the floating prevention structure for a buried construction capable of simply and surely preventing floating even when the construction is small-sized or one which does not require earth retaining by a circumferential sheet pile. SOLUTION: The bottom board outer face 12a of a common ditch 12 is made symmetrical on an axial center M, and made both side upward curved line shapes. A block layer 13a brought into contact with the bottom board outer face 12a performs a base board supporting the common ditch 12, and a support member such as a pile 14 is provided on the lower side. In addition, a block layer 13b is brought into contact with the side 12b of the common ditch 12. Even when excessive gap water produces in a ground at the time of an earthquake and collides with the bottom board outer face of the common ditch 12 according to the floating prevention structure, it is uniformly dispersed, smoothly flows in the water discharge passage 15a of the block layer 13a coinciding with the bottom board outer face of both the side upward curved line shape, enters the water discharge passage 15c of the block layer 13b brought into contact with the side 12b of the common ditch 12, climbs the water discharge passage 15c, and flows out on the ground through non-liquefaction ground 2c including crushed stone 18 or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an underground structure such as a common ditch or a semi-underground structure such as a valve pit used for burying pipes for various uses such as gas, electric power and water supply underground. These are simply referred to as buried structures).

[0002]

2. Description of the Related Art In recent years, floating of a buried structure due to excessive pore water pressure (hereinafter referred to as pressure) generated by ground liquefaction caused by an earthquake has become a problem, and various measures have been taken to prevent floating due to the pressure. Is being considered.

FIG. 5 is a view showing an example of a structure for preventing a structure from being lifted by a conventional sheet pile surrounding system. 2a, 2b
Is a ground that is easily liquefied, such as sand, and here, the structure is a common groove.

[0005] As shown in FIG. 5, the side surface of the common groove 1 and the lower part thereof are surrounded by a sheet pile 3, so that the ground 2 a outside the sheet pile 3 liquefies during an earthquake, and the excess ground 2 a rises at that time. Prevents pore water from transmitting to the bottom of the common groove 1,
In addition to suppressing the occurrence of pressure, the ground 2b inside the sheet pile enclosure
Is restrained by the sheet pile 3 to prevent the common groove 1 from rising due to liquefaction. Reference numeral 4 denotes a tie rod.

[0005] However, when the cross-sectional width of the buried structure is large, the ground restraining effect of the sheet pile during the earthquake does not work effectively, the ground on the lower surface of the buried structure liquefies, and the applied pressure is the sum of its own weight and the overlaid load. There is a problem that it is not possible to prevent the floating.

Japanese Unexamined Patent Publication (Kokai) No. 3-275813 discloses an improvement in the above-mentioned floating prevention structure.

FIG. 6 is a view showing an example of a structure for preventing a structure from being lifted by a conventional improved sheet pile enclosing method, and FIG.
It is a figure which shows an example of the liquefaction suppression sheet pile used for. 5 are denoted by the same reference numerals, and description thereof is omitted.

In the construction of the common groove 1 with concrete in place, a liquefaction-suppressed sheet pile 5 is used as a retaining sheet pile, and the bottom of the construction of the common groove 1 is shaped with crushed stone (Kuriishi) 6.
After cutting the upper part of the liquefaction-suppressed sheet pile 5, the liquefaction-suppressed sheet piles 5 are joined to each other with the tie rods 4, and a crushed stone mat 7 for drainage is formed at the upper position of the liquefaction-suppressed sheet pile 5 and backfilled. The liquefaction suppressing sheet pile 5 is a steel pipe sheet pile having male and female joints 8 and 9 having a drainage function. A large number of openings 10 are formed in a predetermined section of the steel pipe. A filter 11 is provided to prevent the occurrence of water, and the inside of the steel pipe is used as a drainage space.

[0009]

However, the above-mentioned conventional measures for preventing the floating of the buried structure have the following problems.

[0010] In the sheet pile enclosing method shown in Fig. 5, as described above, the sheet pile is simply provided, and if the cross-sectional width of the buried structure is large, the ground restraining effect of the sheet pile during an earthquake does not work effectively. However, the ground on the lower surface of the buried structure liquefies, and the applied pressure becomes larger than the sum of its own weight and the overlaid load, so that it is impossible to prevent floating.

The improved sheet pile enclosing method disclosed in Japanese Patent Application Laid-Open No. Hei 3-27513 is expected to have an effect as compared with the system in which the sheet pile is simply encircled.
b must be surrounded by a liquefaction inhibiting sheet pile 5,
If the depth of the liquefied ground is large, the liquefaction-preventing sheet pile 5 must be large, and a small structure such as a valve pit or a buried structure around the buried structure is not required. For the thing, the liquefaction-preventing sheet pile 5 must be prepared only for the prevention of floating, and the cost such as the material cost increases.

The present invention has been made to solve the above problems, and does not require a small structure such as a valve pit or an earth retaining structure using a sheet pile around a buried structure. Another object of the present invention is to provide a floating structure for a buried structure which can easily and reliably prevent the floating.

[0013]

According to the present invention, there is provided a structure for preventing a buried structure from being lifted up in a ground, wherein an outer surface of a bottom of the buried structure has an upwardly curved shape which is symmetrical with respect to an axis. A block layer having a drainage channel is provided close to or in contact with the side surface and the bottom outer surface of the buried structure, and excess pore water generated in the ground during an earthquake is drained to the ground by the drainage channel and generated on the outer surface of the floor. A floating prevention structure for a buried structure, characterized in that the pressure of excess pore water is reduced.

According to the present invention, excess pore water generated in the ground at the time of an earthquake smoothly flows on the outer surface of the bottom and rises up the drainage channel of the block layer and flows out to the ground. Pressure is not applied, and floating of the buried structure can be prevented.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view showing an embodiment of the present invention, FIG. 2 is a perspective view of a block below the outer surface of a bottom of a common groove used in the present invention, and FIG. It is a perspective view of the block of the side of the common groove used. Parts common to those in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted.

The common groove 12 is buried in the ground 2a that is easily liquefied during an earthquake. Non-liquefied ground 2c
It is.

The outer surface 12a of the bottom of the common groove 12 is curved upward on both sides symmetrically with respect to the axis M indicated by a dashed line. The degree of the angle of the curved shape with respect to the horizontal may be such that the excess pore water colliding with the bottom outer surface 12a can rise without generating the pressure.

Bottom outer surface 12a and side surface 1 of common groove 12
The block layer 13 is provided in contact with 2b.
The block layer 13a in contact with the bottom outer surface 12a is
It also serves as a base for supporting the common groove 12. A support member such as a pile 14 is provided below the block layer 13a. The number of the code piles 14 can be appropriately determined according to the size of the common groove 12 and the like.

The block layer 13b is in contact with the side surface 12b of the common groove 12. 2d is a foundation ground to which the pile 14 is fixed.

For the block layers 13a and 13b, general concrete, reinforced concrete or the like is used.

The block layers 13a and 13b are
The installation work is easy, and the drainage channel can be reliably formed at the time of installation. In addition, the blocks and the like can be held horizontally and stored easily.

The block layer 13a is formed in a curved shape so that the side of the common groove 12 that contacts the bottom surface 12a of the common groove 12 coincides with the upward curved shape on both sides of the bottom surface 12a of the common groove 12, and faces the both sides of the bottom surface 12a. A drainage channel 15a is provided along the curved shape.

The lower side in contact with the opposite ground is a drainage channel 1
Openings of a plurality of vertical drains 15b communicating with 5a are provided.

A water-permeable filter 17a is provided on the lower side in contact with the ground so that sand and the like do not enter the drainage channel 15b.

If necessary, the block layer 13a may be provided with a rectangular block layer in which the drainage passages 15b are made to coincide with each other so as to overlap the lower side.

On the other hand, in the block layer 13b, a drainage channel 15c is provided in the vertical direction on the side that contacts the side surface 12b of the common groove 12, and a drainage channel 15d is provided in the vertical direction on the opposite side that contacts the ground. ing.

As shown in FIG. 3, the block layer 13b is made of a block 16 having an appropriate size for convenient installation.
Are stacked and the drainage channels 15c and 15d are made to coincide with each other. In addition, the block layer 13b may be, if necessary,
A plurality of blocks 16 may be arranged in the horizontal direction.

A water-permeable filter 17b is attached to the surface of the block layer 13b on the side in contact with the ground, and
So that sand and the like are not mixed in.

Crushed stones 18 and the like are laid on the surface of the uppermost block layer 13b so that excess pore water generated during an earthquake can flow out to the ground. Further, a drainage channel may be provided in the non-liquefied ground.

According to the above-described structure for preventing the rise of the common groove 12, even if excessive pore water is generated in the ground during an earthquake and the excessive pore water collides with the outer surface of the bottom of the common groove 12, the water is uniformly dispersed. And flows smoothly through the drainage channel 15a of the block layer 13a which is made to coincide with the outer surface of the bottom plate having a curved shape facing upward on both sides.
Drainage channel 1 of block layer 13b in contact with side surface 12b
5c, ascends the drainage channel 15c, passes through the non-liquefied ground 2c containing the crushed stones 18 and the like, and flows out to the ground.

The excess pore water generated in the ground 2a on the side surface of the common groove 12 does not directly affect the rising of the common groove 12, but enters the drainage channel 15b of the block layer 13b.
It rises in the drainage channel 15b, passes through the non-liquefied ground 2c containing the crushed stones 18 and the like, and is discharged to the ground.

As a result, the pressure is not applied to the outer surface of the bottom of the common groove 12 and the floating can be prevented.

In the above embodiment, the case where the block layer 13 is in contact with the bottom outer surface 12a and the side surface 12b of the common groove 12 has been described. However, while the drain passages 15a and 15c are maintained, an adhesive such as mortar is applied. Can be interposed.

FIG. 4 is a perspective view showing a still another embodiment of the present invention, which has a cutout. Here, the block layer shown in FIGS. 2 and 3 is used for a structure for preventing the valve pit from floating. Common parts have the same reference numerals.
In the valve pit 19, a valve 21 joined to a pipe 20 by a flange 22 is provided.

The outer surface 19a of the bottom of the valve pit 19 is curved upward on both sides symmetrically with respect to the axis N indicated by a dashed line.

Block layers 13a and 13b are provided in contact with the bottom outer surface 19a and side surface 19b of the valve pit 19. The block layer 13a in contact with the bottom outer surface 19a also serves as a base supporting the valve pit 19. A support member such as a pile (not shown) is provided below the block layer 13a.

The block layer 13a is formed on the side of the valve pit 19 in contact with the bottom outer surface 19a so as to correspond to the upwardly curved shape on both sides of the bottom outer surface 19a corresponding to FIG. There is provided a drainage channel 15a (shaded and invisible) toward. Also, on the lower side in contact with the opposite ground, a vertical drainage channel 15b communicating with the drainage channel 15a (not visible as a shadow)
Openings are provided.

A water-permeable filter 17a is provided on the lower side in contact with the ground so that sand and the like do not enter the drainage channel 15b.

In the block layer 13b, a drainage channel 15c is provided in the vertical direction on the side that contacts the side surface 19b of the valve pit 19, and a drainage channel 15d is provided in the vertical direction on the opposite side that contacts the ground.

A water-permeable filter 17b is attached to the side surface of the block layer 13b that contacts the ground so that sand and the like do not enter the drainage channel 15d.

Crushed stones (not shown) are laid on the surface of the uppermost block layer 13b so that excess pore water generated during an earthquake can flow out to the ground. Further, an outflow channel may be provided in the non-liquefied ground.

According to the above structure for preventing the valve pit 19 from rising, excessive pore water is generated in the ground during an earthquake,
Even if excess pore water collides with the bottom outer surface 19a of the valve pit 19, it flows evenly through the drainage channel 15a of the block layer 13a that is evenly distributed and coincides with the bottom outer surface of the upward curved shape on both sides. The water enters the drainage channel 15c of the block layer 13b brought into contact with the side surface 12b, rises the drainage channel 15c, passes through the non-liquefied ground 2c containing the crushed stones 18 and the like, and flows out to the ground.

The excess pore water generated on the side surface of the valve pit 19 does not directly affect the floating of the valve pit 19, but enters the drain 15d of the block layer 13b and rises up the drain 15d. Through the non-liquefied ground 2c containing the crushed stones 18 and the like.

[0045]

As described above, according to the present invention, a simple structure can be applied to a small structure such as a valve pit or a structure which does not require earth retaining with a sheet pile around a buried structure. The floating of the structure can be easily and reliably prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view of a block below an outer surface of a bottom of a common groove used in the present invention.

FIG. 3 is a perspective view of the common groove used in the present invention, which has a partially cut-out side block.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a view showing an example of a structure for preventing a structure from being lifted by a conventional sheet pile surrounding method.

FIG. 6 is a view showing another example of a structure for preventing a structure from being lifted by a conventional sheet pile surrounding method.

FIG. 7 is a view showing an example of a liquefaction-suppressed sheet pile used in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joint groove 2a, 2b Soil which liquefies easily 2c Non-liquefaction ground 2c 2d Foundation ground 3 Sheet pile 4 Tie rod 5 Liquefaction control sheet pile 6 Crushed stone (Kuriishi) 7 Crushed stone mat for drainage 8, 9 Male and female joint 10 Opening 11 Filter DESCRIPTION OF SYMBOLS 12 Common groove 12a Bottom outer surface 12b Side surface 13 Block layer 13a Block layer (bottom outer surface lower side) 13b Block layer (side surface side) 14 Vail 15a, 15b Drainage channel 16 Block 17a, 17b Water-permeable filter 18 Crushed stone 19 Valve pit crushed stone 20 Pipe 21 Valve 22 Flange

Claims (1)

[Claims] 1. A floating prevention structure for a buried structure built in the ground, wherein a bottom layer outer surface of the buried structure has an upwardly curved shape symmetrical with respect to an axial center on both sides, and the block layer having a drainage channel is provided. The excess pore water generated in the ground during an earthquake is provided close to or in contact with the side surface and the bottom outer surface of the buried structure, the excess pore water generated in the ground is discharged to the ground by the drainage channel, and the pressure of the excess pore water generated on the bottom surface of the bottom is reduced. A structure for preventing floating of a buried structure, characterized in that the structure is reduced.