JP6164949B2 - Filling reinforcement structure - Google Patents

Description

  The present invention relates to a reinforcing structure for embankment, particularly earthquake resistance and tsunami resistance.

Conventionally, various reinforcing structures have been proposed for reinforcing embankments such as rivers, coastal dikes, roads, and railways.
Patent Document 1 is an invention that reinforces the embankment against external forces such as during an earthquake or a flood, and continuously installs one or two rows of steel sheet piles up to the support ground inside the embankment. In the case of two rows, a structure is described in which steel sheet pile walls are connected to each other with a connecting material to reinforce the embankment.
In Patent Document 2, in the case of deformation of the lower soft ground or liquefaction during an earthquake, in order to prevent the deformation and collapse, the embankment reinforcement structure that covers both slopes with a restraining member connected to the slope, and further on the slope A gravel drain made of perforated steel pipe piles is created to dissipate excess pore water pressure during an earthquake.
Patent Document 3 describes a reinforcement structure for embankment in which a planar reinforcing material is connected to two rows of underground steel wall bodies without being bridged, and the underground steel body is prevented from being deformed to the outside. ing.
Patent Document 4 describes a reinforcement structure for embankment in which steel sheet piles are diagonally cast along the slope to prevent collapse of the embankment slope due to overflow and flooding.

JP 2003-13451 A JP 2008-25222 A JP 2011-214248 A JP 2011-214254 A

The above-mentioned conventional embankment reinforcement structure prevents deformation and collapse of the embankment against external forces such as earthquakes and floods. It occurs directly underland due to trench-type earthquakes and active faults that occur near the land. A certain reinforcement effect is secured against strong shaking and liquefaction caused by large earthquake motion (Level 2 earthquake motion).
However, in the invention described in Patent Document 1, a tsunami strikes within a short period of time when dissipation of excess pore water pressure during large-scale liquefaction due to a large earthquake does not end, and the wall body is subjected to repeated external forces of large tsunami. If received, the steel sheet pile may exceed the total plastic moment. Since the connecting material between the steel sheet piles is a rod member, there is a problem that if the filling material flows out due to overflow, it will not function.
In the invention described in Patent Document 2, overflow and osmotic failure due to tsunami are not considered.
In the invention described in Patent Document 3, the deformation of the steel sheet pile wall is prevented by utilizing the frictional resistance of the planar reinforcing material, and the certainty of suppressing deformation during liquefaction is low.
In the invention described in Patent Document 4, when liquefaction occurs, the effect of suppressing the settlement of the wall is small.
These conventional embankment reinforcement structures may not be able to resist the tsunami that reaches after the earthquake due to the large amount of embankment sinking in the double cut-off, such as when the super soft ground or the liquefied layer is very thick. . In addition, if the tsunami strikes within a short period of time when the excess pore water pressure during liquefaction does not end, the reaction force expected for the padded soil cannot be obtained, so the double cut-off dam body part is sufficient for the tsunami. There is a possibility that you cannot compete.

  The present invention has been made in view of the above-described problems in the prior art, and is mainly constructed by rivers, coastal dikes or materials that are liable to be liquefied, which are built on the ground where liquefaction is likely to occur due to a trench-type earthquake. An object of the present invention is to provide an embankment reinforcement structure that can suppress deformation of the embankment body and prevent collapse from a combined disaster of liquefaction and tsunami.

Invention of Claim 1 for solving the above subject is steel which penetrated embankment from the top edge of embankment, was embedded in the ground under embankment, and was extended in two rows along the continuous direction of embankment A double-cutting steel sheet pile wall made of sheet piles, and a gravel drain penetrating through the filling soil in the double-cutting steel sheet pile wall to the ground below the embankment, and the upper surface of the filling soil is Placed below the top,
Furthermore, in the double-cutting steel sheet pile wall,
A connecting material for connecting the two rows of steel sheet piles to each other across the filling soil;
A water shielding sheet covering the upper surface of the filling soil,
A foundation rubble layer formed on the connecting material and the water shielding sheet,
A water retaining layer formed on the foundation rubble layer, which includes a water collecting pipe extending along the continuous direction of the embankment,
The gravel drain is connected to the foundation rubble layer through an opening provided in the water shielding sheet, and the water collecting pipe is connected to a drainage structure outside the double-cutting steel sheet pile wall. It is a reinforcement structure for embankment.

  The invention according to claim 2 is the embankment reinforcing structure according to claim 1, wherein a plurality of the gravel drains are continuously provided at intervals along the continuous direction of the embankment to form a row.

  According to a third aspect of the present invention, in the second aspect, the rows along the continuous direction of the embankment of the gravel drain are provided in one or more rows on both sides of the center line between the two rows of steel sheet piles. It is the embankment reinforcement structure of description.

  According to a fourth aspect of the present invention, the connecting material is mainly a sheet material that is long in the direction crossing between the two rows of steel sheet piles, and a plurality of the connecting materials are continuously provided at intervals along the continuous direction of the embankment. It is the reinforcement structure of the embankment as described in any one of Claim 1 to Claim 3 currently used.

  The invention according to claim 5 is any one of claims 1 to 4, wherein a single-grain crushed stone that holds a gap for water retention is disposed inside the water retention layer and outside the water collecting pipe. The embankment embankment reinforcement structure described in 1.

According to the present invention, even when a combined disaster of liquefaction and tsunami occurs mainly due to a trench-type earthquake, the pore water pressure dissipating effect of gravel drain is exerted in the double-cutting steel sheet pile wall constituted by embankment, and the excess gap The water rises through the gravel drain, is temporarily stored in the water retention layer through the foundation rubble layer, and is discharged out of the double-cutting steel sheet pile wall through the water collection pipe. Therefore, liquefaction within the double-cutting steel sheet pile wall is suppressed.
Moreover, even if a tsunami that overflows the embankment occurs, the outflow of the filling soil in the double-cutting steel sheet pile wall is suppressed by the water shielding sheet.
As described above, even if a combined disaster of liquefaction and tsunami occurs, liquefaction in the double-cutting steel sheet pile wall and outflow of filling soil are suppressed, so the connecting material that connects the two rows of steel sheet piles together It functions by being supported by the filling soil, and it is possible to prevent the collapse of the embankment body by suppressing the sinking of the top end and the decrease in the ground rigidity, thereby preventing the collapse.
In addition, excess pore water that has risen through the gravel drain is temporarily stored in the water retention layer through the foundation rubble layer, so there is no eruption or fountain from the top surface of the embankment. Damage to the end surface is prevented.

It is sectional drawing of the reinforcement structure of the embankment which concerns on one Embodiment of this invention. It is sectional drawing of the embankment reinforcement structure which concerns on one Embodiment of this invention, and shows the case where the existing embankment is raised and a reinforcement structure is given. It is sectional drawing of the reinforcement structure of the embankment which concerns on one Embodiment of this invention, and shows the detailed cross section of the upper part containing the top edge of embankment. It is a schematic plan view of the top edge part of the embankment which shows the state in the middle of construction of the reinforcement structure of the embankment which concerns on one Embodiment of this invention. It is a top view for showing the structure of spanning of two rows of steel sheet piles and a connection material in the reinforcement structure of embankment concerning one embodiment of the present invention. It is the top view (a) and AA sectional drawing (b) which drew the upper surface etc. of the water shielding sheet in the reinforcement structure of the embankment concerning one embodiment of the present invention. It is the top view (a) and BB sectional view (b) for showing the drainage structure in the reinforcement structure of the embankment which concerns on one Embodiment of this invention.

  An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

  First, the embankment reinforcement structure according to an embodiment of the present invention will be described. 1 and 2 schematically show the embankment reinforcing structure of the present embodiment. Note that FIG. 2 shows a case where the existing dike is raised. The embankment reinforcement structure is not different between FIG. 1 and FIG. This reinforcing structure can be applied to new and existing dikes, and can be raised as shown in FIG.

As shown in FIGS. 1 and 2, a bank 20 is built on the ground 10. In FIG. 2, the embankment 20 includes a raised embankment 21. The embankment reinforcement structure of the present embodiment includes double-cutting steel sheet pile walls 1, 1 made of steel sheet piles 1, 1 extending in two rows, and a gravel drain 2.
The steel sheet pile 1 penetrates the embankment 20 from the top end 22 of the embankment 20 and is embedded in the ground 10 below the embankment 20. Specifically, the steel sheet pile 1 penetrates the surface layer 11 and the soft layer 12 and is embedded in the hard layer 13. As the excess interstitial water in the embankment rises, the filling soil 3 and the soft layer 12 are ground that has a high possibility of liquefaction, and the steel sheet pile 1 is provided through the ground.
As shown in FIG. 4, the steel sheet piles 1 are extended in two rows along the continuous direction of the embankment 20. Specifically, the steel sheet piles 1 are arranged at substantially symmetrical positions around the center line C in the width direction of the top end 22 of the embankment 20.

The gravel drain 2 passes through the filling soil 3 in the double-cutting steel sheet pile wall 1, 1 and is provided up to the ground 10 below the embankment 20. Since the gravel drain 2 is for draining excess pore water from the soft layer 12 at the time of an earthquake, it is preferably provided so as to penetrate at least the soft layer 12, and is provided throughout as shown in the figure. Further, it may penetrate into the hard layer 13 below the soft layer 12.
As shown in the drawing, the upper surface of the filling pad 3 is arranged at a position lower than the top end 22. Since the gravel drain 2 is excavated downward from the medium filling soil 3, the upper end of the gravel drain 2 is exposed on the upper surface of the medium filling soil 3.

The upper ends of the two rows of steel sheet piles 1, 1 protrude upward from the upper surface of the filling pad 3. A pothole is formed with the upper surface of the filling soil 3 as the bottom surface, and the following elements are provided here. Details are shown in FIG.
That is, the embankment reinforcing structure of the present embodiment includes a connecting material 4 for connecting two rows of steel sheet piles 1 and 1 to each other in the double-cutting steel sheet pile walls 1 and 1 and over the padding soil 3. It has a water-impervious sheet 5 that covers the upper surface of the padded soil 3, a foundation rubble layer 6 formed on the connecting material 4 and the water-impervious sheet 5, and a water retention layer 7 formed on the foundation rubble layer 6. . The top 8 is laid with concrete 8.

  The water retention layer 7 includes a water collection pipe 7a. As the water collection pipe 7a, a porous concrete pipe is preferable. Single-grain crushed stones 7b and 7c are disposed inside the water-retaining layer 7 and outside the water collecting pipe 7a to retain a gap for retaining water. The particle size of the single-grain crushed stone 7c arranged around the water collecting pipe 7a is made smaller than the single-grain crushed stone 7b arranged in the upper region of the gravel drain 2. In addition, the spread sand 9a is spread on the foundation of the basic rubble 6a, and the spread sand 9b is spread on the foundation of the single grain crushed stone 7c.

The water collecting pipe 7a is also extended along the continuous direction of the embankment 20 as shown in FIG.4 and FIG.7 (a).
A plurality of gravel drains 2 are continuously provided at intervals along the continuous direction of the embankment to form a row. In this embodiment, there are two rows. Further, the number of gravel drains 2 may be increased in order to improve the drainage performance of excess pore water. In that case, it is preferable that the row | line | column along the continuous direction of the embankment of the gravel drain 2 is provided in the row | line | column of the center line C between the two rows of steel sheet piles 1 and 1, respectively. As shown in FIG. 4, it is easy to excavate a vertical hole for constructing the gravel drain 2 in charge of the side close to the own machine by the auger combined press machines 100 and 100 each constructing one row of sheet pile walls. Because there is. For example, when the one side auger press-fitting machine 100 constructs the gravel drains 2 in two rows, there are two rows on one side and four rows on both sides.
The water collecting pipe 7a is arranged in the vicinity of the steel sheet pile 1 and has two rows on both sides. The gravel drain 2 is disposed between the water collecting pipes 7a and 7a in plan view.

The connecting material 4 is composed of a sheet material having high tensile rigidity such as a carbon fiber sheet. As shown in FIG. 5, a sheet material that is long in the direction across the two rows of steel sheet piles 1 and 1 is mainly used. In order to connect the two rows of steel sheet piles 1 and 1 to each other, the grooved steel material 41 and the turnbuckle 42 are further applied in the present embodiment.
As shown in FIG. 6, the channel steel 41 is disposed on the inner surface of the steel sheet pile 1 and is passed and fixed in the horizontal direction so as to connect the adjacent steel sheet piles 1, 1, 1,. As shown in FIG. 6 (b), the end of the connecting member 4 is passed through the space between the steel sheet pile 1 and the grooved steel member 41, goes around the grooved steel member 41, and is fixed in a loop by the impregnated adhesive resin 43. As a result, the connecting member 4 is connected to the steel sheet pile 1 via the grooved steel member 41. The connecting material 4 is similarly connected to the steel sheet piles 1 on both sides, and the tensile force is adjusted by the intermediate turnbuckle 42. As shown in FIG. 5, a plurality of connecting members 4 (including turnbuckles 42) are continuously provided at intervals along the continuous direction of the embankment.

The water shielding sheet 5 is disposed on the upper side of the connecting material 4. The water-impervious sheet 5 is provided with an opening in a portion corresponding to the upper end surface of the gravel drain 2. The gravel drain 2 is connected to the basic rubble layer 6 through this opening, and drainage from the gravel drain 2 to the basic rubble layer 6 and further to the water retention layer 7 becomes possible. This opening may be one opening that exposes the entire upper end surface of the gravel drain 2, or may be a plurality of holes arranged on the upper end surface of the gravel drain 2. It may be a mesh-like member that covers the end face.
The impervious sheet 5 is intended to promote effective drainage of excess pore water through the gravel drain 2 from the soft layer 12 in the double-cutting steel sheet pile walls 1, 1, and the padding soil 3 absorbs by the tsunami overflow. Since it is for the purpose of preventing being discharged, it is provided so as to cover the entire surface of the filling soil 3 around the gravel drain 2. As shown in FIG. 6 (b), the side edge of the water-impervious sheet 5 extends to the inner side surface of the steel sheet pile 1 and is wound into the filling soil 3. As the water-impervious sheet 5, for example, a water-impervious nonwoven fabric is applied.

The water collecting pipe 7a is connected to a drainage structure to the outside of the double-cutting steel sheet pile wall 1,1. FIG. 7 shows an example of the configuration.
For example, water collecting basins 7d as shown in FIG. 7 are provided in the water retention layer 7 at predetermined intervals along the continuous direction of the embankment. The end of the water collection pipe 7a is connected to the water collection tank 7d, and the drain pipe 14 is connected to the water collection tank 7d. A drain pipe 14 is extended outside the double-cutting steel sheet pile wall 1,1. About the part which lets the drain pipe 14 pass, a hole or a notch is provided in the steel sheet pile 1 suitably. A structure in which a slope downflow 15 and a side groove 16 are provided following the drain pipe 14 is illustrated. Any drainage structure such as a simpler structure may be used as long as drainage from the water collecting pipe 7a to the outside of the double-cutting steel sheet pile walls 1 and 1 is possible.

Next, the construction procedure of the embankment reinforcement structure of this embodiment will be described.
The auger combined press-fitting machine 100 includes a chuck and an auger for gripping a steel sheet pile, and can perform an auger combined press-fitting method in which a part of a space for press-fitting a steel sheet pile is excavated by the auger and the steel sheet pile is press-fitted.
First, as shown in FIG. 4, the steel sheet pile 1 is press-fitted into the top end 22 by the auger combined press machine 100 and a steel sheet pile wall having a predetermined length is formed. The auger screw is placed on the formation position of the gravel drain 2 by turning, and the vertical hole for constructing the gravel drain 2 is excavated by rotating and lowering the auger screw. While raising the auger screw, the crushed stone is thrown into the vertical hole to form the gravel drain 2. In addition, the digging, backfilling, and compacting of the filling soil 3 are appropriately performed.
Further, the auger combined press machine 100 repeats the extension of the steel sheet pile wall and the formation of the gravel drain 2 in order.
The double auger steel sheet pile wall 1, in the continuous direction of the embankment by repeating the extension of the steel sheet pile wall and the formation of the gravel drain 2 by operating the auger combined press machine 100 on both sides of the top end 22. 1 and gravel drain 2 are constructed.
It is preferable to shorten the construction period by operating the auger combined press machine 100 on one side of the top end 22 and operating the other auger combined press machine 100 on the other side of the top end 22.

Next, from the part where the construction of the double cut-off steel sheet pile walls 1 and 1 and the gravel drain 2 is finished, the connection and fixing of the grooved steel material 41 to the steel sheet pile 1 and the connection by the connection material 4 (including the turnbuckle 42) are performed. carry out. Further, the water shielding sheet 5 is laid on the filling material 3 and the connecting material 4 (including the turnbuckle 42).
Next, foundation rubble 6a is laid on top of the water-impervious sheet 5, and further, a water collecting pipe 7a is installed on the top of the foundation rubble layer 6, and single-grain crushed stones 7b and 7c are filled so that the surface layer portion is the water retaining layer 7 To do.
Furthermore, this is constructed at the installation position of the drainage structure outside the double-cutting steel sheet pile walls 1 and 1 described above.

According to the embankment reinforcement structure of the present embodiment described above, even if a combined disaster of liquefaction and tsunami occurs mainly due to a trench-type earthquake, in the double cut-off steel sheet pile walls 1 and 1 configured in the embankment 20, The pore water pressure dissipating effect of the gravel drain 2 is exerted, and the excess pore water rises through the gravel drain 2 and is temporarily stored in the water retention layer 7 through the foundation rubble layer 6 and double cut steel through the water collecting pipe 7a. It is discharged out of the sheet pile walls 1 and 1. Therefore, liquefaction in the double cutoff steel sheet pile walls 1 and 1 is suppressed.
Moreover, even if the tsunami which overflows the embankment 20 arises, the outflow of the filling soil 3 in the double cut-off steel sheet pile walls 1 and 1 is suppressed by the water shielding sheet 5.
Even if the embankment that constitutes the slope progresses due to the tsunami, the outflow of the filling soil 3 in the double-cutting steel sheet pile wall 1, 1 is suppressed, and the double-cutting steel sheet pile wall 1, 1 Since they are constrained to each other by the connecting material 4, the proof strength of the levee body section partitioned by the double-cutting steel sheet pile walls 1 and 1 is maintained, and the levee function is maintained.
As described above, even if a combined disaster of liquefaction and tsunami occurs, the liquefaction in the double-cutting steel sheet pile wall 1, 1 and the outflow of the filling material 3 are suppressed, so two rows of steel sheet piles 1, 1 The connecting material 4 that connects the two to each other is also supported by the filling soil 3 to function, and the sinking of the top end and the lowering of the ground rigidity are suppressed, so that deformation of the embankment body can be suppressed and collapse can be prevented.
In addition, the excess pore water that has risen through the gravel drain 2 is temporarily stored in the water retention layer 7 via the foundation rubble layer 6, so that there is no eruption sand / fountain from the top surface 22 of the embankment. Damage to the surface portion of the top end 22 of the embankment is prevented.

DESCRIPTION OF SYMBOLS 1 Steel sheet pile 2 Gravel drain 3 Filling soil 4 Connecting material 5 Water shielding sheet 6 Foundation rubble layer 6a Foundation rubble 7 Water retention layer 7a Catchment pipes 7b, 7c Single grain crushed stone 7d Catchment basin 8 Concrete 9a Led sand 9b Led sand 10 Ground 11 Surface layer 12 Soft layer 13 Hard layer 14 Drain pipe 20 Embankment 21 Raised embankment 22 Top end 41 Grooved steel 42 Turnbuckle 43 Impregnated adhesive resin C Center line

Claims (5)

A double-cutting steel sheet pile wall made of steel sheet piles penetrating the embankment from the top of the embankment, embedded in the ground below the embankment, and extended in two rows along the continuous direction of the embankment;
A gravel drain penetrating the padding in the double-cutting steel sheet pile wall and provided to the ground under the embankment, and
The upper surface of the filling is disposed at a position lower than the top edge;
Furthermore, in the double-cutting steel sheet pile wall,
A connecting material for connecting the two rows of steel sheet piles to each other across the filling soil;
A water shielding sheet covering the upper surface of the filling soil,
A foundation rubble layer formed on the connecting material and the water shielding sheet,
A water retaining layer formed on the foundation rubble layer, which includes a water collecting pipe extending along the continuous direction of the embankment,
The gravel drain is connected to the foundation rubble layer through an opening provided in the water-impervious sheet, and the water collecting pipe is connected to a drainage structure outside the double-cutting steel sheet pile wall. Filling reinforcement structure.   2. The embankment reinforcement structure according to claim 1, wherein a plurality of the gravel drains are continuously provided at intervals along the continuous direction of the embankment to form a row.   3. The embankment reinforcement structure according to claim 2, wherein the gravel drains along the embankment continuous direction are provided on each side of a center line between the two rows of steel sheet piles.   The said connection material mainly has a sheet | seat material long in the direction crossing between the said 2 rows of steel sheet piles, and is provided with two or more continuously at intervals along the continuous direction of embankment. Item 4. The embankment reinforcing structure according to any one of items 3 to 4.   The embankment reinforcement structure according to any one of claims 1 to 4, wherein single-grain crushed stones are disposed in the water retention layer and outside the water collecting pipe to maintain a gap for water retention.

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