JP6301421B2 - Maintenance method for liquefaction prevention of existing embankment - Google Patents

Description

  The present invention is a maintenance method for liquefaction countermeasures for an existing embankment that suppresses deformation of the existing embankment constructed above the foundation ground, and in particular, even if the foundation ground liquefies during an earthquake. The present invention relates to a maintenance method for preventing liquefaction of an existing embankment that suppresses deformation of an existing embankment constructed on the ground.

  Conventionally, as a maintenance method for countermeasures against liquefaction of existing embankments, a shear deformation constraining wall was constructed from the bottom edge of the embankment structure into the foundation ground, and the embankment structure is In the embankment structure for railways and roads, a drain pipe is provided so as to incline toward the center, and a plurality of beams are provided in the vicinity of the shear deformation restraint wall along the depth direction of the shear deformation restraint wall. A liquefaction countermeasure method is known (see, for example, Patent Document 1).

JP 2005-016231 A

  However, the conventional liquefaction countermeasure method for the above-mentioned embankment structure for railways and roads is used for drilling and excavation such as deep mixing processing machines that drill, excavate, and agitate the foundation ground in the outer edge area of the bottom of the method.・ It is necessary to construct a heavy machinery scaffold for agitation heavy machinery with heavy machinery such as a drag excavator. Furthermore, drilling and excavation such as a deep mixing processing machine, and drilling and excavation to a deep underground location with agitation heavy machinery It is necessary to install drainage pipes and beams by grinding and stirring, or to improve the ground by pouring a large amount of cement, and it is necessary to remove the heavy machinery scaffolding by heavy machinery such as drag excavators, making construction difficult and difficult There was a problem of being.

Therefore, the present invention solves the problems of the prior art as described above, that is, the object of the present invention is to provide a solution on the foundation ground even when the foundation ground liquefies during an earthquake . An object of the present invention is to provide a liquefaction countermeasure maintenance method for an existing embankment in which the integrity of a non-liquefaction monolithic structure that suppresses deformation of the outer edge of the existing embankment created upward is enhanced.

The liquefaction countermeasure maintenance method for the existing embankment that is the invention according to claim 1 is a method of removing the butt portion of the existing embankment formed above the foundation ground, and a removal area of the butt portion . And a bottom bottom foundation ground excavation process in which a bottom bottom foundation ground is excavated to form a drilling area by excavating a bottom bottom foundation ground located below a region near the outer edge of the bottom section , and a drilling region in which the bottom bottom foundation ground is excavated A non-liquefied integrated structure installation step for installing a non-liquefied integrated structure made of crushed stone and a reinforcing sheet, and an embankment collapse prevention weight made up of futon, chestnut and presser embankment above the non-liquefied integrated structure The above-mentioned problem is solved by comprising an embankment collapse inhibiting weight setting step for installing a slab, and the reinforcing sheet is made of sheet-like geosynthetics or a wire mesh.
Here, “the bottom of the bottom of the hoshiri” refers to a foundation ground in a range in which the hoshiri is supported so that the hoshiri does not collapse in a state before the foundation ground is liquefied.

  In addition to the configuration of the existing embankment liquefaction countermeasure maintenance construction method described in claim 1, the invention according to claim 2 of the present invention includes the embankment collapse suppression weight installation step that is repeatedly applied, and the embankment collapse suppression weight However, at least a part of the lower-layer side futon ridge and the upper-layer side futon ridge is assembled on the outer edge side of the presser foot embankment and laminated at a steep slope from the slope of the existing embankment, as described above. The problem is further solved.

  In addition to the construction of the existing embankment liquefaction countermeasure maintenance method described in claim 1 or claim 2, the invention according to claim 3 includes a bowl-shaped gabion filled with the chestnut stone, A sheet-like reinforcing floor extending from the bottom surface of the gabion, and the gabion has a frame portion that forms an internal space composed of six surfaces filled with the chestnut, and a mesh size smaller than the chestnut. And a net-like net part attached to the six surfaces consisting of the frame part, and the reinforcing floor material extends from the frame parts on both sides of the bottom surface of the gabion, The above-described problems are further solved by comprising a mesh-like floor net part attached to the floor frame part.

In addition to the configuration of the existing embankment liquefaction countermeasure maintenance construction method described in claim 3, the invention according to claim 4 is characterized in that the embankment collapse prevention weight installation step is the excavation area with respect to the slope of the existing embankment. Assembling a gabion on the far end side of the floor and extending a reinforcing floor material from the gabion toward the slope of the existing embankment, assembling a futon basket, and filling a chestnut stone into the interior space of the gabion, It further comprises the presser embankment laying work that spreads and compacts the presser embankment on the upper surface of the reinforcing floor material installed between the gabion and the slope of the existing embankment, thereby further solving the above-mentioned problems It is.

  In addition to the construction of the existing embankment liquefaction countermeasure maintenance construction method described in claim 4, the invention according to claim 5 is characterized in that the embankment collapse prevention weight installation step includes the reinforcement before the futon reed assembly work. By having the reinforcing sheet bottom laying work for laying the sheet on the bottom surface, the above-described problems are further solved.

In addition to the configuration of the existing embankment liquefaction countermeasure maintenance construction method according to any one of claims 1 to 5, the geosynthetics is a method of the existing embankment. A plurality of vertical bands extending along a direction from the far end side to the near end side of the excavation area with respect to the surface and horizontal bands that connect and reinforce the plurality of vertical bands are entangled and arranged in a lattice pattern. In addition, the above-described problem is further solved by the fact that the longitudinal band is composed of a core material layer made of a high-strength polyester long fiber bundle and a coating layer made of a polyethylene resin covering the core material layer. .

  In addition to the configuration of the liquefaction countermeasure maintenance method for the existing embankment described in any one of claims 1 to 6, the invention according to claim 7 includes the non-liquefaction integrated structure installation step, Lower crushed stone laying work for laying crushed stone on the bottom side of the excavation area, reinforcing sheet laying work for laying a reinforcing sheet after the lower crushed stone laying work, and upper crushed stone laying for laying crushed stone again after the reinforcing sheet laying work The above-described problem is further solved by forming a non-liquefied integrated structure in the excavation region, which is composed of construction work and in which the reinforcing sheet is sandwiched between the crushed stones.

  According to the eighth aspect of the present invention, in addition to the configuration of the existing embankment liquefaction countermeasure maintenance method described in any one of the first to sixth aspects, the non-liquefied integrated structure installation step A lower reinforcing sheet laying work for laying a reinforcing sheet on the bottom side of the excavation area, a crushed stone laying work for laying crushed stone after the lower reinforcing sheet laying work, and a crushed stone laying work for the laying The upper reinforcing sheet laying work for laying the reinforcing sheet again after the reinforcing sheet connecting work, and the reinforcing sheet connecting work for connecting the outer peripheral ends of the reinforcing sheet for the upper reinforcing sheet laying work and the reinforcing sheet for the lower reinforcing sheet laying work. The above-described problem is further solved by forming a non-liquefaction integrated structure in which the crushed stone is wrapped with the reinforcing sheet in the excavation region.

The liquefaction countermeasure maintenance method for the existing embankment of the present invention not only can suppress the deformation of the existing embankment created above the foundation ground even when the foundation ground liquefies during an earthquake. The following unique effects can be obtained.

According to the liquefaction countermeasure maintenance method for the existing embankment of the invention according to claim 1, a method for removing the butt portion of the existing embankment formed above the foundation ground, and a removal region of the butt portion And a bottom bottom foundation ground excavation step of excavating a bottom bottom foundation ground located below the outer edge vicinity region of the bottom section and forming a drilling region;
A non-liquefied integrated structure installation step of installing a non-liquefied integrated structure made of crushed stone and a reinforcing sheet in an excavation area excavating the lower bottom foundation ground, and a futon in the upper part of the non-liquefied integrated structure And a landslide-inhibiting weight installation process for installing a landslide-inhibiting weight consisting of chestnut and presser embankment, and the reinforcing sheet is made of sheet-like geosynthetics or wire mesh, so that Since the embankment collapse prevention weight that acts on the compaction of the non-liquefied integrated structure installed below the outer edge of the section uses futons and chestnuts to increase the shape retention of the presser foot, The crushed stone below and the reinforcing sheet made of geosynthetics or wire mesh generate friction force between them to form a non-liquefaction integrated structure that is resistant to bending deformation. Outside When the outer area foundation ground of the liquefaction is liquefied, the non-liquefaction integrated structure is located almost as a rigid board than the liquefied outer area foundation ground, and is transformed into the existing embankment when an earthquake occurs Even when a force to slide the arc occurs, the embankment collapse prevention weight, which is installed on the slope of the existing embankment and has improved shape retention, compacts the non-liquefied integrated structure. The frictional resistance against sliding movement is continuously increased to suppress deformation, and stabilization can be achieved by avoiding the slipping and destruction of the bottom edge of the existing embankment.
In addition, there is no need to install heavy machinery scaffolding as in the conventional liquefaction countermeasure maintenance method, installation of drain pipes and beams by deep excavation of the foundation ground, ground improvement by pouring a large amount of cement, etc. And shortening the construction period.
In addition, there is no need to temporarily remove the inner central part of the existing embankment from the slope and to excavate the central foundation ground below the inner central part of the existing embankment. Because there is no need to do so, an emergency vehicle can pass even during construction.
In addition, the non-liquefied integrated structure is excellent in air permeability, and excess water in the existing embankment is released to the ground surface outside the buttock via the non-liquefied integrated structure, and before the existing embankment is liquefied. Since the water in the existing embankment is drained through the non-liquefied integrated structure at this stage, liquefaction of the existing embankment can be avoided.

  According to the liquefaction countermeasure maintenance method for the existing embankment of the invention according to claim 2, in addition to the effect of the invention according to claim 1, the embankment collapse prevention weight installation process is repeatedly performed, and the embankment collapse prevention weight is However, at least part of the lower-layer side futon ridge and the upper-layer side futon ridge are assembled on the outer edge side of the presser embankment, and the layers are stacked at a steep slope from the slope of the existing embankment. The embankment collapse prevention weight has a structure in which the outer edge side of the presser embankment installed on the existing embankment side is surrounded by a solid wall, and the wall of the embankment collapse prevention weight is steeply sloped to load more than the gentle slope presser embankment. Therefore, the compaction on the far end side with respect to the slope of the existing embankment of the non-liquefied integrated structure is further strengthened, and the frictional resistance can be further increased to suppress deformation.

According to the liquefaction countermeasure maintenance method for the existing embankment of the invention according to claim 3, in addition to the effect exhibited by the invention according to claim 1 or claim 2, the futon is a bowl-shaped gabion filled with chestnut It consists of a sheet-like reinforcing floor material extending from the bottom surface of this gabion, and the gabion has a frame part that forms an internal space consisting of six surfaces filled with chestnuts, and a mesh size smaller than that of chestnuts A mesh-like net part attached to six surfaces consisting of a frame part, and a reinforcing floor material extends from the frame part on both sides of the bottom surface of the gabion, and the floor frame part By being composed of a mesh-like floor net part attached in between, the futon has excellent shape retention with respect to external force, and suppresses the deformation of the embankment collapse prevention weight.
In addition, the futon straw has excellent air permeability inside and outside the gabion and above and below the reinforcing floor material, so that moisture in the existing embankment is easily drained through the embankment collapse prevention weight. It is possible to avoid liquefaction of the embankment.

According to the liquefaction countermeasure maintenance method of the existing embankment of the invention according to claim 4, in addition to the effect exhibited by the invention according to claim 3, the embankment collapse prevention weight installation step is performed by the excavation with respect to the slope of the existing embankment. Assembling the gabion on the far end side of the area and extending the reinforcing floor material from the gabion toward the slope of the existing embankment, assembling the futon, assembling the chestnut stone into the interior space of the gabion, and gabion And the embankment embankment laying work that spreads and compacts the presser embankment on the upper surface of the reinforcing floor material installed between the slope and the existing embankment slope, so that the wall of the embankment collapse prevention weight is futon In a narrow space where the land boundary is adjacent to the outer edge side of the existing embankment, it is made strong by the formation of the gabion and the chestnut filled in this gabion. We installed the embankment collapse deterrence weigh also it is possible to stabilize the existing embankment.
In addition to the non-liquefied integrated structure, the embankment collapses because the drainage of excess moisture inside the existing embankment through the presser embankment is enhanced due to the excellent breathability of the chestnut filled in the futon. The groundwater and seepage water inside the presser foot embankment with restraint weight and existing embankment are discharged to the ground surface outside the hoshiri to prevent the water level from rising as soon as it accumulates. Even when a force to cause slipping is generated, liquefaction of the existing embankment can be suppressed.

  According to the existing liquefaction countermeasure maintenance method of the invention according to claim 5, in addition to the effect of the invention according to claim 4, the embankment collapse restraining weight installation process is reinforced before the futon ridge assembly work By having the reinforcement sheet bottom laying work that lays the sheet on the bottom surface, a large-scale embankment collapse prevention weight is placed so that the edge of the reinforced floor material of the futon wall is away from the slope of the existing embankment Even if it is necessary to provide the floor, the length of the reinforced floor material of the futon laid between the stacked embankment prevention weights is replenished by adjusting the length of the reinforcing sheet. It can have versatility according to the scale of the embankment collapse prevention weight.

According to liquefaction countermeasures maintenance method of the existing embankment of the invention according to the claims 6, in addition to the invention exhibits the effect according to any one of claims 1 to 5, geosynthetics is, the existing embankment A plurality of vertical belts extending along the direction from the far end side to the near end side of the excavation area with respect to the slope are formed by entangled and arranged in a lattice form with horizontal bands that connect and reinforce the plurality of vertical belts The vertical belt is composed of a core material layer made of a bundle of high-strength polyester long fibers and a coating layer made of a polyethylene resin that covers the core material layer, so that the vertical belt of geosynthetics can be Because it extends along the perspective direction from the same butt portion as the direction of the force to be deformed, the sheet tensile strength of the geosynthetics is reliably exhibited, and there are multiple geosynthetic lateral bands. Phase Since linked to, can geosynthetics to effectively suppress deformation of the existing embankment to sufficiently exhibit a sheet-like shape retention.
Further, the longitudinal band is composed of a core material layer made of a high-strength polyester long fiber bundle and a coating layer made of a polyethylene resin covering the core material layer, so that the high-strength polyester long fiber bundle of the core material layer is formed. And the polyethylene resin of the coating layer exhibit weather resistance, chemical resistance, cold resistance, heat resistance, and corrosion resistance, so that the durability of geosynthetics can be maintained over a long period of time and deformation of the existing embankment will be prolonged. Can be maintained throughout.

  According to the liquefaction countermeasure maintenance method for the existing embankment of the invention according to claim 7, in addition to the effect produced by the invention according to any one of claims 1 to 6, the non-liquefaction integrated structure installation step However, the lower crushed stone laying work to lay crushed stone on the bottom side of the excavation area, the reinforcing sheet laying work to lay the reinforcing sheet after this lower crushed stone laying work, and the upper crushed stone to lay the crushed stone again after this reinforcing sheet laying work By constructing a non-liquefaction monolithic structure with a reinforcing sheet sandwiched between crushed stones in the excavation area, a structure in which a reinforcing sheet is sandwiched between crushed stone layers is formed. In order to suppress the occurrence of liquefaction of the non-liquefied integrated structure by generating a large frictional force in between, the embankment installed above the non-liquefied integrated structure on the foundation ground below the Houshiri in the event of an earthquake Collapse prevention weight To prevent the occurrence of deformation or arc sliding, it is possible to suppress the deformation or collapse of existing embankment.

  According to the liquefaction countermeasure maintenance method of the existing embankment of the invention according to claim 8, in addition to the effect produced by the invention according to any one of claims 1 to 6, the non-liquefaction integrated structure installation step However, the lower reinforcement sheet laying work for laying the reinforcement sheet on the bottom side of the excavation area, the crushed stone laying work for laying the crushed stone after the lower reinforcement sheet laying work, and the crushed stone laying work for this laying From the upper reinforcing sheet laying work for laying the reinforcing sheet later, and the reinforcing sheet connecting work for connecting the outer peripheral ends of the reinforcing sheet for the upper reinforcing sheet laying work and the reinforcing sheet for the lower reinforcing sheet laying work. By forming a non-liquefaction integrated structure in which the crushed stone is wrapped with a reinforcing sheet in the excavation region, a structure in which a layer of crushed stone is wrapped with the reinforcing sheet is formed between the reinforcing sheet and the crushed stone. In addition to generating a strong frictional force and increasing the integrity of the non-liquefied integrated structure, it is important to prevent embankments from being collapsed when the earthquake occurred. The deformation and collapse of the existing embankment can be suppressed by preventing the deformation of the ridge and the occurrence of the arc slip.

The partial cross section perspective view which shows the concept of the existing embankment applied in a present Example. FIG. 3 is a front cross-sectional view showing a method for removing a buttock as viewed from reference numeral 2 shown in FIG. Front sectional drawing which shows a Houshiri downward foundation ground excavation process. Front sectional drawing which shows the lower layer crushed stone installation construction of a non-liquefaction integrated structure installation process. Front sectional drawing which shows the reinforcement sheet | seat installation construction of a non-liquefaction integrated structure installation process. The top view which shows the geosynthetics applied in a present Example. Front sectional drawing which shows the upper layer crushed stone laying construction process of a non-liquefaction integrated structure installation process. Front sectional drawing which shows the reinforcement sheet laying construction of the embankment collapse prevention weight installation process. Front sectional drawing which shows the futon basket assembly construction and the chestnut filling construction of the embankment collapse prevention weight setting process. The perspective view which shows the futon which is applied in a present Example. Front sectional drawing which shows the presser embankment laying construction of the embankment collapse prevention weight installation process. Front sectional drawing which shows the state which repeated the embankment collapse suppression weight installation process, and laminated | stacked the embankment collapse suppression weight. (A) (B) is a figure which compares and shows the water level by the liquefaction countermeasure maintenance construction method which is a present Example. (A) (B) is a figure which compares and shows the effect by the liquefaction countermeasure maintenance construction method which is a present Example.

The present invention includes a method of removing a method butt portion of an existing embankment formed above a foundation ground, and a method of forming a digging region below a method butt portion and an outer edge of the method butt portion. The foundation ground excavation process, the non-liquefaction integrated structure installation process in which a non-liquefaction integrated structure composed of crushed stones and reinforcing sheets is installed in the excavation area, and the futons and chestnuts and the presser foot above the non-liquefaction integrated structure It is equipped with an embankment collapse prevention weight installation process that installs an embankment collapse prevention weight consisting of embankment, and the reinforcement sheet is made of sheet-like geosynthetics or wire mesh, so that the foundation ground will be liquefied in the event of an earthquake If it provides a liquefaction countermeasure maintenance method for the existing embankment that strengthens the integrity of the non-liquefied integrated structure that suppresses deformation of the outer edge of the existing embankment created above the foundation ground even if it occurs Its specific Embodiments with is, but may be any of those.

For example, geosynthetics is a general term for geotextiles, geomembranes, and geocomposites. If it is a sheet-like material such as a woven structure, a lattice structure, a stitch structure, or a non-woven fabric, its material is suitable for the weather environment, Any one that has chemical resistance, cold resistance, heat resistance, and corrosion resistance, such as metal fibers such as stainless steel and titanium alloy, and resin fibers such as polypropylene resin, polyester resin, and polyamide resin. Even if it exists, it is sufficient if it can be laid.
Further, the foundation ground may be any ground as long as it is likely to be liquefied due to an earthquake or the like.
Moreover, the embankment material used for the embankment embankment is any one of an embankment material obtained by improving the soil generated on site, a viscous soil, a sandy soil, a gravelly soil, a landslide, and a crushed stone having a particle size of 40 mm or less. It doesn't matter.

Below, the liquefaction countermeasure maintenance construction method of the existing embankment which is one Example of this invention is demonstrated based on FIG. 1 thru | or FIG.
Here, FIG. 1 is a partial cross-sectional perspective view showing the concept of the existing embankment to which the present embodiment is applied, and FIG. 2 is a front cross-sectional view showing the process of removing the tail edge as viewed from the reference numeral 2 shown in FIG. 3 is a front cross-sectional view showing the Hashiri lower foundation ground excavation process, FIG. 4 is a front cross-sectional view showing the lower crushed stone laying work in the non-liquefaction integrated structure installation process, and FIG. FIG. 6 is a front sectional view showing a reinforcing sheet laying work in a non-liquefaction integrated structure installation process, FIG. 6 is a plan view showing geosynthetics applied in this embodiment, and FIG. 7 is a non-liquefaction integrated structure. FIG. 8 is a front cross-sectional view showing the upper layer crushed stone laying work of the structure installation process, FIG. 8 is a front cross-sectional view showing the reinforcement sheet laying work of the embankment collapse prevention installation process, and FIG. 9 is the embankment collapse prevention weight. It is a front cross-sectional view showing the futon mochi assembly work and the chestnut filling work of the installation process, 10 is a perspective view showing a futon to which the present embodiment is applied, FIG. 11 is a front sectional view showing a presser embankment construction work in the embankment collapse prevention weight setting process, and FIG. 12 is an embankment collapse prevention weight. FIG. 13A is a front sectional view showing a state in which the embankment collapse prevention weight is stacked by repeating the installation process, and FIG. 13A is an existing embankment when the liquefaction countermeasure maintenance method according to this embodiment is applied to the existing embankment. FIG. 13B is a conceptual cross-sectional view showing the water level of the existing embankment when nothing is applied to the existing embankment as a comparative example, and FIG. 14A is the present embodiment. It is a conceptual sectional view showing the effect at the time of applying the liquefaction countermeasure maintenance construction method which is an example to existing embankment, and Drawing 14 (B) is a conceptual sectional view when nothing is given to existing embankment as a comparative example.

Existing embankment 110 according to an embodiment of the present invention, as shown in FIG. 1, a road embankment has been made concrete above the foundation bed B, also referred to as existing ground.
As an example, the existing embankment 110 created above the foundation ground B has a height of 10 m and a width of 15 m on the one-side slope portion 111.
The foundation ground B is not a viscous soil layer but a so-called liquefied layer of sandy ground.
The liquefaction countermeasure maintenance method of the existing embankment of this embodiment is to suppress the deformation of the existing embankment 110 created on the foundation ground even when the foundation ground B causes liquefaction in the event of an earthquake, It includes a method of removing the bottom of the bottom of the bottom of the base, a step of excavating the foundation bottom of the bottom of the bottom of the base, a step of installing a non-liquefied integrated structure, and a step of installing a pile to prevent embankment collapse.

As shown in FIG. 2, in the slope bottom removal step, for example, the slope bottom 111 of the existing embankment 110 created above the foundation ground B is removed with a heavy machine such as a drag excavator.
As shown in FIG. 3, the bottom bottom foundation ground excavation step is performed below the removal region A1 of the bottom portion 111 removed in the bottom portion removal step and the outer edge region A2, which is a region near the outer edge of the bottom portion 111. Excavation area A3 is formed by excavating the located bottom bottom foundation ground B1.
For the excavation area A3, for example, the depth is 2 m, the outside is a position 2 m outward from the end of the slope 111, and the inside intersects with an imaginary line 45 ° below the fast edge of the flat upper portion of the existing embankment 110. Position.
The reason for setting the depth to 2 m is that if the depth is such a level, excavation can be performed without the need for earth retaining.

The non-liquefaction monolithic structure installation step is a step of installing a non-liquefaction monolithic structure 120 composed of a crushed stone composed of the lower layer crushed stone 121 and the upper layer crushed stone 123 and the reinforcing sheet 122 in the excavation area. Reinforcement sheet laying work and upper crushed stone laying work are provided.
As shown in FIG. 4, in the lower crushed stone laying work in the non-liquefied integrated structure installation process, first, crushed stones are formed on the bottom surface in the excavation area A <b> 3 of the lower bottom foundation ground B <b> 1 excavated in the lower bottom foundation foundation excavation process. The lower crushed stone 121 is formed, and, for example, leveling is performed to flatten the lower crushed stone 121 with a heavy machine such as a vibrating roller, and compaction is performed by rolling.
Next, as shown in FIG. 5, in the reinforcement sheet laying work in the non-liquefaction integrated structure installation step, a reinforcement sheet 122 made of geosynthetics or a wire mesh is laid on the lower crushed stone 121.

As shown in FIG. 6, the geosynthetics used as the reinforcing sheet 122 is formed by, for example, a plurality of vertical belts 122a and a horizontal belt 122b that connects and reinforces the vertical belts 122a in a grid pattern. High strength reinforced geosynthetics type.
As a result, the geosynthetics vertical band 122a is held by the sheet holding means, and the geosynthetics horizontal band 122b connects the plurality of vertical bands 122a to each other.
The reinforcing sheet 122 made of geosynthetics sufficiently exhibits the sheet-like shape retention.
The vertical belt 122a is composed of a core layer made of a bundle of high-strength polyester long fibers in which high-strength polyester long fibers are closely arranged in parallel and a coating layer made of polyethylene resin that covers the core layer.

As an example, the width W of the vertical band 122a is 80 to 95 mm, the strength of the vertical band 122a is 9 to 130 kN / piece, and the pitch P of the vertical band 122a is 100 to 180 mm.
Thereby, the high-strength polyester long fiber bundle surely exhibits the sheet tensile strength in the longitudinal direction of the reinforcing sheet 122 and compensates for the resistance to slip which is insufficient in the embankment.
In addition, the high-strength polyester long fiber bundle in the core layer and the polyethylene resin in the coating layer increase the safety against damage during construction resistance, and show weather resistance, chemical resistance, cold resistance, heat resistance, and corrosion resistance. ing.

The front and back surfaces of the vertical belt 122a are subjected to uneven processing, and by this uneven processing, between the lower layer crushed stone 121 and the upper layer crushed stone 123, between the crushed stone and the foundation ground B, between embankment materials, etc. Thus, the friction coefficient between the objects to be contacted up and down is improved.
In addition, the extending direction (longitudinal direction) of the vertical belt 122a extends along the perspective direction from the slope which is the inside / outside direction of the slope 111, that is, the width direction of the existing embankment 110 (in FIG. 5). The reinforcing sheet 122 made of geosynthetics is laid so as to be in the left-right direction. In short, the vertical belt 122a extends along the direction from the far end side to the near end side of the excavation region A3 with respect to the slope of the existing embankment 110.

Subsequently, as shown in FIG. 7, in the upper layer crushed stone laying work of the non-liquefied integrated structure installation step, the upper layer crushed stone 123 is put on the reinforcing sheet 122 made of geosynthetics, In the same manner as the lower layer crushed stone 121, for example, the lower layer crushed stone 121 is leveled with a heavy machine such as a vibrating roller and compacted by rolling.
Thereby, the reinforcing sheet 122 made of geosynthetics laid between the lower layer crushed stone 121 and the upper layer crushed stone 123 generates a frictional force between the lower layer crushed stone 121 and the upper layer crushed stone 123, and is a non-liquefaction integrated body that is resistant to bending deformation. A structure 120 is formed.

In addition, when the lower layer crushed stone 121 and the upper layer crushed stone 123 are only crushed stones having a particle size of more than 40 mm, the number of contacts between the crushed stone and the reinforcing sheet 122 made of geosynthetics is reduced, and the load per contact point is within an allowable range. Therefore, the reinforcing sheet 122 made of geosynthetics may be damaged.
Therefore, in this embodiment, the crushed stone used for the lower layer crushed stone 121 and the upper layer crushed stone 123 is mixed with crushed stones of various sizes having a particle size of 40 mm or less.
Accordingly, the number of contact points between the crushed stone used in the lower crushed stone 121 or the upper crushed stone 123 and the reinforcing sheet 122 made of geosynthetics is appropriately increased, and a desired frictional force is generated and the reinforcement made of geosynthetics. Damage to the sheet 122 is prevented.

The embankment collapse prevention weight installation process includes a reinforcing sheet 131, a futon ridge 132, a chestnut stone 133, and a presser embankment 134 above the non-liquefaction integrated structure 120. The embankment is steeper than the slope of the slope of the existing embankment 110. This is a process of installing a collapse prevention weight 130, and includes a reinforcing sheet bottom laying work, a futon basket assembly work, a chestnut filling work, and a presser embankment laying work.
Here, the reinforcing sheet 131 is the same as the reinforcing sheet 122 made of geosynthetics or wire mesh used in the non-liquefaction integrated structure 120, thereby reducing the number of parts on the construction site. Can do.
Further, even when it is necessary to provide a large-scale embankment collapse prevention weight 130 in which the edge of the reinforcing floor material 132b of the futon ridge 132 is located away from the slope of the existing embankment 110, the lamination The length of the reinforcing floor material 132b of the futon folds 132 laid between the embankment collapse prevention weight 130 is supplemented by adjusting the length of the reinforcement sheet 131, and according to the scale of the embankment collapse prevention weight stacked. Versatility is obtained.

As shown in FIG. 8, in the reinforcement sheet bottom laying work in the embankment collapse prevention weight installation process, the reinforcement sheet 122 made of geosynthetics is laid on the upper layer crushed stone 123 that becomes the bottom surface of the embankment collapse prevention weight 130.
Here, the reinforcing sheet bottom laying work for laying the reinforcing sheet 131 above the non-liquefied integrated structure 120 has a narrow width of the embankment collapse prevention weight, and the embankment collapse that is laminated by the reinforcing floor material 132b of the futon basket 132. If the frictional force between the restraining weights can be secured, it may be omitted.

As shown in FIG. 9, in the futon basket assembly work in the embankment collapse prevention weight installation process, the futon basket 132 is assembled and installed on the upper surface of the reinforcing sheet 131.
Here, as shown in FIG. 10, the futon ridge 132 is composed of a ridge-shaped gabion 132a and a sheet-shaped reinforcing floor material 132b.

The gabion 132a is installed on the far end side of the excavation area A3 with respect to the slope of the existing embankment 110.
The gabion 132a has a shape that can open and close the upper surface and can be filled with crushed stone and crushed stone, for example, a rectangular parallelepiped outer shape, and a framework frame that forms an internal space composed of six surfaces filled with crushed stone. These are rectangular parallelepiped gabions that are each attached to each of the six surfaces of the frame part and are composed of a net-like net part that holds chestnuts and crushed stone filled in the internal space of the frame part.
Note that a partition wall may be provided inside the gabion 132a to partition the gap into a plurality.
The reinforcing floor material 132b includes a floor frame portion extending from the frame portions on both sides of the bottom surface of the gabion 132a toward the direction close to the slope of the existing embankment 110, and a mesh attached between the floor frame portions. And is laid on the upper surface of the reinforcing sheet 131.

For the frame portion, for example, a steel bar having a diameter of 16 mm or 13 mm is used.
In addition, for example, a steel wire having an inner diameter of 2.7 mm and an outer diameter of 3.7 mm that is coated with a lower layer by hot-dip zinc-5% aluminum alloy plating and an upper layer by PVC coating is used for the net part. In addition, by knitting this steel wire, a mesh-shaped mesh having a mesh size smaller than that of chestnut stone 133 or crushed stone, for example, a mesh inner size of 80 mm, is used.
Thereby, the futon bag 132 becomes excellent in shape retention property with respect to external force.

Moreover, the futon 132 has excellent air permeability inside and outside the gabion 132a.
Further, the upper and lower crushed stones 123 or the presser embankment 134 or the lower non-contact material such as the reinforcement sheet 131 made of geosynthetics and the upper presser embankment 134 are desired above and below the reinforcing floor material 132b. The frictional force is generated and the air permeability is excellent.

  Note that the futon basket 132 can be any of the gabion 132a and the reinforcing floor material 132b, which are integrally formed, or the separate gabion 132a and the reinforcing floor material 132b assembled at the installation site. Even if it is a thing, as long as it can fill the inside of the gabion 132a and hold the crushed stone 133 and the crushed stone, it does not matter.

The chestnut filling work is performed following the futon straw assembly work in the embankment collapse prevention weight setting process, and the internal space of the gabion 132a of the futon straw 132 is filled with the chestnut stone 133 or the crushed stone.
The chestnuts 133 or crushed stones to be filled in the gabion 132a are mixed with, for example, crushed stones or crushed stones of a size larger than various mesh internal sizes having a particle size of 80 mm or more so as not to fall out from the net part of the gabion 132a and flow out. .
As a result, the gabion 132a of the futon ridge 132 creates a gap between the filled chestnut stones 133 and has excellent air permeability. Therefore, the gabion 132a is free from excess moisture inside the existing embankment 110 via the presser embankment 134. Drainage becomes high.

As shown in FIG. 11, in the presser embankment laying work in the embankment collapse prevention weight setting process, the embankment material is thrown into the upper surface of the reinforcing floor material 132b installed between the gabion 132a and the slope of the existing embankment 110. Thus, for example, using a heavy machine such as a vibrating roller, the pressering embankment 134 is formed by repeating the leveling of the embankment material having a thickness of 30 cm or less and the compaction by rolling.
As described above, the embankment collapse prevention weight installation step described above inhibits embankment collapse above the non-liquefaction integrated structure 120 formed below the removal area A1 of the hail 111 and the outer edge area A2 of the hail 111. A weight 130 is formed.

As shown in FIG. 12, when the embankment collapse prevention weight installation process is repeatedly performed and a plurality of embankment collapse prevention weights 130 are stacked, the lower layer installed at the outer edge side of the presser embankment 134 is installed in the previous process. The futon ridge 132 is assembled so that at least a part of the gabion 132a in the side futon ridge 132 and the gabion 132a in the upper layer futon ridge 132 installed in the subsequent process overlap, and the slope is steep from the slope of the existing embankment 110 Are stacked.
Thereby, the stacked embankment collapse prevention weight 130 has a structure in which the outer edge side of the presser embankment 134 installed on the existing embankment side is surrounded by a strong wall surface.

Further, the embankment collapse prevention weight 130 that acts on the compaction of the non-liquefaction monolithic structure 120 installed below the outer edge of the existing embankment 110 and the outer edge of the outer embankment 110 has the futon ridge 132 and the chestnut 133. It is used to increase the shape retaining property of the presser embankment 134 and to increase the load compared to the presser embankment with a gentle gradient by making it steep.
Thereby, compared with the inner edge side of the non-liquefaction integrated structure 120, the integrity of the outer edge side is increased, and it is possible to further suppress the slope portion 111 of the existing embankment 110 from being deformed or slidingly broken in an arc shape.
Then, by making the embankment collapse prevention weight steep, it is possible to install the embankment collapse prevention weight even in a narrow space where the site boundary is adjacent to the outer edge side of the existing embankment 110.

Next, FIG. 13 (A) and FIG. 13 (B) show changes in the water level due to groundwater and seepage water inside the existing embankment 110 created above the foundation ground B by applying the liquefaction countermeasure maintenance method of the present invention. Will be described.
As shown in FIG. 13 (A), the non-liquefied integrated structure 120 and the embankment collapse prevention weight 130 on the non-liquefied integrated structure 120 by the liquefaction countermeasure maintenance method of the existing embankment are air permeable. The excess water inside the existing embankment 110 is discharged to the ground surface outside the buttock.

The lower layer crushed stone 121 and the upper layer crushed stone 123 of the non-liquefied integrated structure 120 are excellent in air permeability.
Therefore, as shown by the arrow in the drawing, the water contained in the soil of the existing bank 110 before the liquefaction of the existing bank 110 passes through the non-liquefaction integrated structure 120 and the existing bank as shown by the arrow in the drawing. Drained outside 110.

In addition, chestnuts filled in futon are also highly breathable.
Therefore, the moisture contained in the soil of the presser embankment 134 of the embankment collapse prevention weight 130 is not only drained to the outside of the existing embankment 110 via the gabion 132a of the futon ridge 132, as indicated by an arrow in the figure, Since excess moisture inside the existing embankment 110 is also discharged to the outside of the existing embankment 110 through the presser embankment 134 and the gabion 132a of the futon ridge 132, the drainage of the existing embankment 110 is generally improved.
As a result, in addition to the non-liquefaction monolithic structure, the groundwater and seepage water inside the presser embankment and the existing embankment for preventing collapse of the embankment are actively discharged to the ground surface outside the outer edge of the hail, and the water level rises due to accumulation. The water level is kept at a low position.

On the other hand, as shown in FIG. 13B, in the comparative example in which the non-liquefaction integrated structure 120 and the embankment collapse prevention weight 130 are not installed, the moisture contained in the soil of the existing embankment 110 is difficult to drain. .
Therefore, groundwater and seepage water are accumulated inside the existing embankment, and the water level is high.

Then, the effect by having installed the non-liquefaction integrated structure 120 and the embankment collapse weight is demonstrated using FIG. 14 (A) and FIG. 14 (B).
Here, as a premise, when an earthquake occurs, among the foundation ground B shown in FIGS. 14 (A) and 14 (B), the existing foundation lower foundation ground B3 that supports the existing construction 110 below the existing construction 110 is Since the restraining effect is large, such as the contact force between sand particles is large under the load of the existing embankment 110, it is difficult to liquefy.
On the other hand, the outer region foundation ground B2, which is located outside the existing foundation lower foundation ground B3 and does not support the existing construction 110, is not affected by the load of the existing construction 110, and the contact force between the sand particles is small. Therefore, it is easy to liquefy.

As shown in FIG. 14 (A), a non-liquefied integrated structure 120 and a plurality of embankment collapse prevention weights 130 are laminated on the non-liquefied integrated structure 120 by the liquefaction countermeasure maintenance method for the existing embankment 110. Then, when the water level inside the existing embankment 110 is kept low, and the outer area foundation ground B2 which is an outer area than the non-liquefied integrated structure 120 is liquefied in the event of an earthquake, the existing embankment The non-liquefaction monolithic structure 120 supporting the embankment collapse prevention weight 130 installed in place of the 110 butt is positioned so as to be hardly washed away as a board having higher rigidity than the liquefied outer region foundation ground B2. At the same time, the embankment collapse prevention weight 130 supported by the non-liquefaction integrated structure 120 supports the existing embankment 110.
Therefore, even if an earthquake occurs and the outer region foundation ground B2 that is an outer region from the non-liquefaction integrated structure 120 is liquefied, the slope 111 of the existing embankment 110 is deformed or slipped into an arc shape. In other words, the deformation of the existing embankment 110 formed above the foundation ground B is suppressed while avoiding sliding and being destroyed.

On the other hand, as shown in FIG. 14 (B), in the comparative example in which the non-liquefaction integrated structure 120 is not installed, when the outer region foundation ground B2 is liquefied, the slope bottom portion 111 of the existing embankment 110 is supported. Not.
In addition, since the water level inside the existing embankment 110 is high, the contact force is also small inside the existing embankment 110, and the restraining effect is small.
Therefore, when an earthquake occurs and the outer region foundation ground B2 in the outer region below the existing embankment lower foundation ground B3 on the lower side of the existing embankment 110 is liquefied, the slope 111 of the existing embankment 110 is deformed or circled. The entire existing embankment 110 is deformed by sliding and breaking in an arc shape.

Furthermore, in the liquefaction countermeasure maintenance method of the existing embankment of this embodiment, the construction of heavy machinery scaffolding as in the conventional liquefaction countermeasure method, the installation of drain pipes and beams in the deep part of the foundation ground B, the foundation ground B There is no need for ground improvement by pouring a large amount of cement.
Further, the temporary removal of the inner center portion of the existing fill 110 formed above the foundation ground B is temporarily removed, the excavation of the existing lower foundation ground B3 located below the inner center portion of the existing fill 110, and the existing There is no need to remove the road installed at the center of the embankment 110.

  Further, before the existing embankment 110 is liquefied, the non-liquefied integrated structure 120 is excellent in air permeability, and excess moisture existing in the existing embankment is removed through the non-liquefied integrated structure 120. In addition to being discharged to the ground surface outside 111, the wall surface formed by the gabion 132a for preventing collapse of the embankment has excellent air permeability, and the groundwater and seepage water inside the presser embankment and the existing embankment can be drained to the ground outside the buttock. It releases to the surface and prevents the water level from rising due to accumulation.

In the non-liquefaction integrated structure installation step, a non-liquefaction integrated structure 120 having a sandwich structure in which a reinforcing sheet 122 made of geosynthetics or a metal net is sandwiched between crushed stones made of a lower crushed stone 121 and an upper crushed stone 123 is formed. However, a lower reinforcing sheet laying work for laying a reinforcing sheet on the bottom side of the excavation area A3 of the lower bottom foundation ground B1, and a crushed stone laying work for laying a crushed stone after the lower reinforcing sheet laying work, After the crushed stone laying work for laying, the outer peripheral end portions of the upper reinforcing sheet laying work for laying the reinforcing sheet again and the reinforcing sheet for the upper reinforcing sheet laying work and the reinforcing sheet for the lower reinforcing sheet laying work are connected to each other. A non-liquefaction monolithic structure in which the crushed stone is wrapped with the reinforcing sheet may be formed in the excavation region.
Thereby, it becomes the structure which wrapped the layer of crushed stone with the reinforcement sheet | seat, and a large frictional force is generated between a reinforcement sheet | seat and crushed stone, and the integrity of a non-liquefaction integrated structure is increased.

110 ・ ・ ・ Existing embankment 111 ・ ・ ・ Hoshiri 120 ・ ・ ・ Non-liquefied integrated structure 121 ・ ・ ・ Lower crushed stone (crushed stone)
122 ... Geosynthetics (reinforcing sheet for non-liquefied integrated structure)
123 ... Upper layer crushed stone (crushed stone)
130 ・ ・ ・ Embankment collapse prevention weight 131 ・ ・ ・ Geosynthetics (Reinforcing sheet for embankment collapse prevention weight)
132 ・ ・ ・ Futon 籠 132a ・ ・ Gabion (wall material)
132b .. Reinforcement flooring (filling reinforcement)
133 ・ ・ ・ Kuriishi (Weight stone for Futon 籠)
134 ・ ・ ・ Presser embankment (heavy embankment for preventing collapse of embankment)
A1 ・ ・ ・ Removal area of the buttock A2 ・ ・ ・ Outer edge area of the buttock A3 ・ ・ ・ Drilling area (excavation range) of the foundation below the buttock
B ... Basic ground (current ground)
B1 ... Hoshijiri lower foundation ground B2 ... Hoshijiri outer area foundation ground B3 ... Existing bank lower foundation ground

Claims (8)

A process for removing the bottom of the bottom of the existing embankment created above the foundation ground,
A method of excavating the lower leg foundation ground located below the removal area of the outer hip part and the region near the outer edge of the outer leg part to form an excavation area;
A non-liquefaction integrated structure installation step of installing a non-liquefaction integrated structure made of crushed stone and a reinforcing sheet in an excavation area excavated from the lower bottom foundation ground ;
An embankment collapse restraining weight installation step for installing an embankment collapse restraining weight composed of futon crabs, chestnut stones and presser embankments above the non-liquefied integrated structure,
The existing embankment liquefaction countermeasure maintenance method, wherein the reinforcing sheet is made of sheet-like geosynthetics or a wire mesh. The embankment collapse prevention weight installation process is repeatedly performed,
The embankment collapse prevention weight is laminated with a steep slope from the slope of the existing embankment by assembling at least a part of the lower side futon straw and the upper side futon straw on the outer edge side of the presser embankment. The liquefaction countermeasure maintenance method for existing embankments according to claim 1, wherein the existing embankments are liquefied. The futon is composed of a bowl-shaped gabion filled with the chestnut and a sheet-like reinforcing floor extending from the bottom of the gabion,
The gabion has a frame portion forming an internal space composed of six surfaces filled with the chestnut, and a mesh-like net attached to the six surfaces composed of the frame portion having a smaller mesh size than the chestnut stone. And consists of
The reinforcing floor material is composed of a floor frame portion extended from frame portions on both sides of the bottom surface of the gabion, and a mesh-like floor net portion attached to the floor frame portion. The liquefaction countermeasure maintenance construction method of the existing embankment of Claim 1 or Claim 2. The lining collapse prevention weight installation step assembles a gabion on the far end side of the excavation area with respect to the slope of the existing embankment and assembles a reinforcing floor material extending from the gabion toward the slope of the existing embankment.籠 Assembly work, Kuriishi filling work to fill the interior space of the gabion, and presser embankment on the upper surface of the reinforcing floor installed between the gabion and the slope of the existing embankment and tighten The liquefaction countermeasure maintenance method for existing embankments according to claim 3, characterized by comprising presser embankment laying work for hardening.   The said embankment collapse prevention weight installation process has the reinforcement sheet bottom laying construction which lays the said reinforcement sheet on the bottom face before the said futon straw assembly construction, The existing banking of Claim 4 characterized by the above-mentioned. Liquefaction countermeasure maintenance method. The geosynthetics has a plurality of vertical bands extending along a direction from the far end side to the near end side of the excavation area with respect to the slope of the existing embankment, and a horizontal band that connects and reinforces the plurality of vertical bands And are entangled in a lattice pattern,
The longitudinal band is composed of a core material layer made of a high-strength polyester long fiber bundle and a coating layer made of a polyethylene resin that covers the core material layer. The liquefaction countermeasure maintenance method of existing embankment as described in one.   The non-liquefaction integrated structure installation step includes a lower layer crushed stone laying work for laying crushed stone on the bottom side of the excavation region, a reinforcement sheet laying work for laying a reinforcement sheet after the lower layer crushed stone laying work, and the reinforcement sheet laying A non-liquefied integrated structure in which the reinforcing sheet is sandwiched between the crushed stones is formed in the excavation region, the upper layer crushed stone laying work for laying crushed stones again after the construction. The liquefaction countermeasure maintenance method for the existing embankment according to any one of items 6.   The non-liquefaction integrated structure installation step includes a lower reinforcement sheet laying work for laying a reinforcement sheet on the bottom side of the excavation area, and a crushed stone laying work for laying a crushed stone after the lower reinforcement sheet laying work And an outer peripheral edge of each of the upper reinforcing sheet laying work for laying the reinforcing sheet again after the laying crushed stone laying work, and the reinforcing sheet for the upper reinforcing sheet laying work and the reinforcing sheet for the lower reinforcing sheet laying work. 7. The non-liquefaction integrated structure which is comprised from the reinforcement sheet | seat connection construction which connects parts and wraps the said crushed stone with the said reinforcement sheet | seat is formed in the said excavation area | region of Claim 1 thru | or 6 characterized by the above-mentioned. Liquefaction countermeasure maintenance method for existing embankment according to any one.

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