JP2000144747A - Structure and execution method of lightweight banking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute the widening lightweight banking of a structurally stable slope by filling a section between a front wall and the rear slope with foamed plastics and fixing both ends of a surface-shaped tendon to the front wall and the rear slope. SOLUTION: When the widening banking of a slope is constructed, sections among a front wall 3 and the rear slopes are filled with foamed plastics 1.... One ends of surface-shaped tendons 6... such as geo-grids composed of the drawn molded forms of a resin are fixed onto the front wall 3, and the other ends are fastened onto the rear slope. When the lightweight banking is applied to the banking structure of a self-sustaining wall, sections among wall bodies are filled with foamed plastics 1, and both ends of the surface-shaped tendons 6 are fixed onto both wall bodies. Accordingly, fixing is facilitated, the places of fixing can be increased freely, and sufficient tensile force can be ensured easily. Partial concentrated load in a structure can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight embankment using foamed plastic as an embankment material, and more particularly to a structure of a widened lightweight embankment on a slope and a lightweight embankment of a self-supporting wall and a construction method thereof.

[0002]

2. Description of the Related Art In order to reduce the weight of an embankment structure and reduce earth pressure, etc., as a method of widening an embankment on a slope and embankment of a self-supporting wall,
A construction method using an ultralight foamed plastic as an embankment material is known.

[0003] In the widening embankment on a slope, for example, as shown in FIG. 6, a space between a back slope 102 and a front wall 103 is filled with foamed plastic 101 as a banking material. For the purpose of protection and rough terrain, etc., concrete floor slabs 105 and 10
4 are provided.

As described above, by filling the foamed plastic 101 as the embankment material, the earth pressure acting on the back surface of the front wall 103, that is, the active earth pressure can be reduced. However, it is difficult to make the back slope and the foamed plastic filling layer integral, and the reduced earth pressure is still higher than that of a stable slope.
For this reason, in order to secure the stability of the structure, anchor rods 108 are buried in the concrete floor slabs 104 and 105, and one end of the anchor rods is fixed to an H steel pile or the like constituting the front wall 103. At the end, an anchor 109 is buried and fixed deeply on the back slope.

[0005] In the case of a lightweight embankment having a self-standing wall, for example, FIG.
As shown in the figure, a foamed plastic 101 is filled as an embankment material between opposing wall bodies 110a and 110b, and concrete floor slabs 112 and 111 are disposed at the uppermost and intermediate portions of the foamed plastic 101, respectively, as described above. Is done. In addition, in order to ensure the stability of the structure, the anchor rods 108 are installed in the concrete slabs 112 and 111.
Is embedded, and both ends of this anchor rod are
It is stretched and fixed to an H steel pile or the like constituting 110b.

FIG. 8 shows an example of an earth pressure reducing structure.
As shown in the figure, the concrete retaining wall 114 and the back ground 11
There is known a reinforced earth retaining wall composed of a geotextile 116 laid in the inside 5. Such a structure enhances the stability of the slip soil mass 117 and obtains an effect of reducing the earth pressure mainly due to the friction characteristics of the geotextile 116, and secures a sufficient fixing length L to the inner side of the slip surface 118 to secure the geotextile 116. Is laid.

Examples of the geotextile include a sheet made of a water-permeable fiber such as a non-woven fabric or a woven fabric, a mesh structure such as a geogrid or a geonet, in which warp and weft are joined or integrated at intersections, or a lattice-like structure. Sheets of a structure are known. In particular, in the case of the reinforced soil retaining wall shown in FIG. 8, a material having high rigidity against elongation, such as a polymer geogrid, is used as the geotextile 116. As the backfill material on the back of the retaining wall, a material that can greatly expect frictional resistance with the geotextile 116, for example, a fine-grained conglomerate or sandy soil is used.

[0008]

As described above, by using an ultralight foamed plastic as an embankment material,
The earth pressure can be greatly reduced. For example, in a widened embankment on an inclined ground, the width that can be widened can be increased, and a higher structure can be realized in a self-standing wall.

[0009] However, there are various problems in the construction of the conventional widening embankment on the slope and the self-standing wall, as described below. The anchor rods 108 and 109 made of metal used to enhance the stability of the above structure are very expensive and account for a large proportion of the construction cost. In particular,
When constructing a high embankment structure, it is necessary to greatly increase the number of these, and it is difficult to reduce the construction cost. It is difficult to fix the anchor 109 in the widening embankment on the slope. In particular, when the back slope of the lightweight embankment is an embankment, it is assumed that a sufficient tensile force cannot be expected with the anchor, and the anchor excavation length needs to be extremely long. Therefore, it is difficult to shorten the construction period and reduce the total cost. The stabilization method using the anchor rod 108 and the anchor 109 is disadvantageous for an earthquake or the like because it involves intensive load-bearing on the H steel pile or the like constituting the front wall 103 and the walls 110a and 110b. In order to protect the foamed plastic, it is necessary to embed the metal anchor rod in the concrete slab, and the design flexibility of the embankment structure is low, and it is difficult to rationalize the structure.

[0010] In addition, since the above-mentioned construction method using the geotextile 116 for reducing the earth pressure of the retaining wall mainly utilizes frictional resistance between the backfill material and the geotextile, a foamed plastic (particularly, a backfill material) is used. An ultra-light molded product such as a foamed plastic block cannot be applied, and cannot be combined with such an ultra-light embankment. In addition, the reduction of earth pressure by geotextile is limited by design to 1/3 of the horizontal component of the active soil pressure resultant force without geotextile, especially when applied to steep slope widening structures or high self-supporting walls. There is.

The present invention has been made in view of the above circumstances, and provides a novel structure of a lightweight embankment, particularly a widened embankment on a slope or a lightweight embankment having a self-supporting wall. It is an object of the present invention to provide a new structure and construction method of a new lightweight embankment that is stable in nature.

[0012]

The configuration of the present invention which has been achieved to achieve the above object is as follows.

That is, the structure of the lightweight embankment of the present invention comprises a structure having a structure filled with foamed plastic,
It is characterized in that a planar tension member is stretched.

[0014] As the planar tension member, for example, a geogrid made of a stretched product of a resin can be suitably used.

When the structure of the lightweight embankment of the present invention is applied to a widened embankment structure on an inclined ground, for example, as shown in the vertical sectional view of FIG. One end of the sheet-like tension member 6 is fixed to the front wall 3 and the other end is fixed to the back slope 2. When the present invention is applied to the embankment structure of a self-supporting wall, for example, as shown in an upright sectional view of FIG. 4, the foamed plastic 1 is filled between the walls 10a and 10b, and both ends of the sheet-like tendon 6 are formed. It is fixed to the walls 10a and 10b.

In the structure of the lightweight embankment of the present invention,
The degree of freedom of the laying position of the planar tendon is high, and it can be buried in the concrete floor slabs placed at the top or middle of the foam plastic filling layer, or between these concrete floor slabs and the foam plastic filling layer. It can also be arranged between the foamed layers or between the foamed plastic filling layers.

In the method for constructing a lightweight embankment according to the present invention, when constructing a widened embankment structure on a slope, for example, as shown in FIG. 5, a steel pile 13 is mounted with a panel (not shown). A horizontal member 14 is bridged between the steel piles 13 of the front wall 3, one end of the tension member 6 is fixed to the horizontal member 14, and the tension member 6 is spread on a foamed plastic or a concrete floor slab. The method includes a step of fixing the other end of the material 6 to the back slope 2.

Further, when the method for constructing a lightweight embankment of the present invention is applied to, for example, an embankment structure having a self-supporting wall as shown in FIG. 4, it is constructed by attaching a panel to a steel pile similarly to the above example. A horizontal member is bridged between the steel piles of each of the wall bodies 10a and 10b, one end of the tension member 6 is fixed to the horizontal member, and the tension member 6 is spread on a foamed plastic or a concrete floor slab. Further, the method includes a step of fixing the other end of the tension member 6 to a horizontal member between the opposed steel piles.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention realizes a structurally stable lightweight embankment structure by stretching a planar tendon in a structure having a structure filled with foamed plastic. There will be described in detail below with specific examples.

FIGS. 1 to 3 are elevational sectional views showing an example in which the present invention is applied to a widened embankment structure on a slope. In these figures, 1 is a foamed plastic, 2 is a back slope ground, 3 is a front wall, 4 is a concrete floor slab arranged in the middle of the foamed plastic filling layer, and 5 is arranged on the top of the foamed plastic filling layer. A concrete floor slab, 6 is a sheet-like tendon, and 7 is a fixing pin.

In the widening embankment structure of the slope according to the present invention,
In the structure filled with the foamed plastic 1 between the front wall 3 and the rear slope 2, a tension member 6 having the same function as a conventionally used anchor rod is stretched.

Since the tension member 6 has a planar shape, the tension member 6 can be fixed to the front wall 3 and the rear inclined surface 2 reliably and easily, and its tensioning will be described in detail later. 6 can be performed by fixing one end to the front wall 3 and fixing the other end to the inclined back surface 2 with a fixing pin 7 or the like while applying a certain amount of tensile force to the tendon 6.

The planar tension member 6 stretched as described above can avoid local load concentration in the structure, and can be used when a rod-shaped anchor rod and an anchor are used as in the prior art. In comparison, a more structurally stable lightweight embankment structure can be realized.

As the tension member 6, a material having high tensile strength, excellent durability, and particularly high rigidity with respect to elongation can be used. For example, a geogrid (polymer grid) made of a stretched product of a resin can be used. ) Is optimal. The polymer grid is formed by perforating a thick sheet of polyethylene or polypropylene or the like and orienting the polymer of the sheet by heating and stretching in a uniaxial or biaxial direction. Such a polymer grid has a small residual elongation of about 10 to 15%, a tensile strength several times larger than that of an unstretched net, and can have a strength close to mild steel with the same strand. It has physical properties suitable for the intended use of the tendon.

The polymer grid preferably used as the tendon 6 in the present invention is known as a geotextile used for a reinforced earth wall method. Such a reinforced soil wall method reinforces a slipping soil mass by a shear resistance (interlocking effect) exerted by the soil confined and bound to the mesh of the polymer grid and integrated with the grid.

On the other hand, the foamed plastic used as the embankment material for reducing the earth pressure in the present invention can be expected to have an interlocking effect like the soil (gravely soil or sandy soil) in the reinforced earth wall method. Instead, the foamed plastic is usually filled separately from the tendon 6. That is, the tendon 6 such as a polymer grid used in the present invention is:
It works completely different from geotextile in the reinforced earth wall construction method. When used in a tensioned state with both ends fixed, it bears the inertia force of the embankment and disperses and suppresses the load acting on the front wall 3. What to do.

The planar tendon 6 used in the present invention comprises:
Unlike metal rod anchor rods used conventionally, there is no possibility of damaging the foamed plastic. For this reason, the laying position of the tendon 6 is not particularly limited. In addition to being buried in the concrete slabs 4 and 5 as shown in FIG. It can also be arranged between the packing layers or in the foamed plastic packing layer. As shown in FIG. 3, a sheet-like tendon 6 is stretched in the foamed plastic filling layer, and an anchor rod 8 is embedded in the concrete floor slab as in the prior art. A hybrid structure fixed to the slope 2 can also be used.

As the foamed plastic 1, foamed plastic in place can be used, but a foamed plastic block (or foamed plastic plate) which is a molded product
Can be suitably used.

As the foamed plastic block, those having excellent strength and excellent water resistance are preferable. For example, polystyrene foam, polyethylene foam, polyurethane foam and the like can be used. In particular, polystyrene foam (trade name) "Light Fill Block": Dow Chemical Co., Ltd.
Is preferred.

The foamed plastic block is prepared by placing a pre-foamed bead in a mold, heating and cooling to form a predetermined density, and then applying a foaming agent to the molten plastic under high pressure. There is an extrusion foaming method in which a fluid gel is formed by injection mixing and then extruded into the atmosphere to rapidly expand the gel. These can be used alone or in combination as an embankment material. When these are used in combination, it is preferable to arrange the upper layer by extrusion foaming with high compressive strength.

In the above-mentioned widened embankment structure according to the present invention, the earth pressure is greatly reduced by the ultra-lightweight foamed plastic 1 and the embankment body is attached to the flattening member 6 like a conventional anchor rod. Since the load acting on the front wall 3 can be dispersed and deterred,
The stability of the widening embankment structure on the slope can be enhanced. This enables widening embankments, especially on steep slopes, and also allows for an increase in the widenable width.

FIG. 4 is an elevational sectional view showing an example in which the structure of the lightweight embankment of the present invention is applied to an embankment structure of a self-standing wall. FIG.
Among them, 10a and 10b are wall bodies, 11 is a concrete floor slab arranged in the middle of the foamed plastic filling layer, and 12 is a concrete slab arranged on the top of the foamed plastic filling layer.

In the embankment structure of the self-supporting wall according to the present invention, the same tendon 6 is stretched between the walls 10a and 10b in a structure filled with the same foamed plastic 1 as described above. The tension member 6 can be stretched by fixing one end of the tension member 6 to one wall body and fixing the other end to the other wall body while applying a certain tensile force to the tension member 6. it can.

In the example of FIG. 4, the tension members 6 are stretched between the concrete floor slab 12 and the foamed plastic filling layer and in the foamed plastic filling layer. The laying position of the tendon 6 is not particularly limited as long as the stability of the body can be secured.

In the embankment structure of the self-supporting wall according to the present invention as described above, the earth pressure is greatly reduced by the ultra-lightweight foamed plastic 1 and the sheet-like tension member 6 bears the inertia force of the embankment. Since the load acting on the walls 10a and 10b can be dispersed and suppressed, the stability of the embankment structure can be enhanced. Thereby, a structurally stable higher self-standing wall can be constructed.

Next, the method for constructing a lightweight embankment according to the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 5A is an elevational sectional view of a stretched portion of the tendon 6, and FIG. 5B is a plan view showing a stretched state of the tendon 6.

First, a steel pile (H-shaped steel or the like) 13 is inserted into a pre-boring hole such as a large-diameter boring, and concrete is cast. A horizontal member (L-shaped steel or the like) 14 for attaching a tendon material is fixed at a predetermined height between the standing H-shaped steels 13.

Next, the concrete foundation 1 was placed on the bottom of the slope.
5 is formed. The concrete foundation 15 is provided for the purpose of uniformly transmitting the applied load to the ground surface, and is not limited to cast-in-place concrete, but may be formed using precast concrete. Prior to the formation of the concrete foundation 15, in order to secure the strength and levelness of the ground surface, the crushed stone or the like is usually rolled to form the base layer.

Next, a front panel (not shown) made of a concrete panel or the like is attached to the H-shaped steel 13 and the front wall 3 is constructed. H-shaped steel 13
There is a method of externally attaching a metal part or the like to the flange portion, or a method of dropping it inside the flange of the H-shaped steel 13.

Next, the space formed between the back slope 2 and the front wall 3 is filled with foamed plastic 1 which is an embankment material.

When the above-described block molded body is used as the foamed plastic 1 and the piled-up body is filled and filled, as shown in FIG. The backfill material 16 is filled. Further, the block molded bodies are connected to each other as necessary.

After filling the foamed plastic 1 to a predetermined height, the intermediate floor slab 4 is formed. Such an intermediate slab 4
Is provided for the purpose of adjusting the irregularity of the foamed plastic layer, fixing the foamed plastic, dispersing the load, and taking measures against buoyancy, etc., and can be formed using not only cast-in-place concrete but also precast concrete.

Subsequently, after filling the foamed plastic 1 to a predetermined height, as shown in FIG. 5, one end of the sheet-like tension member 6 is wound around a horizontal member 14 bridged between H-shaped steels 13. Then, the tension member 6 is spread on the foamed plastic 1 by using a fixing pin 17 or the like. Further, the other end of the tension member 6 is pulled so that the tension member 6 is in a tension state, and the fixing pin 7 is driven into the rear inclined ground 2 while maintaining this state, thereby fixing the tension member 6 to the rear inclined ground 2.

Subsequently, the mounting of the front panel, the filling of the foamed plastic, the formation of the intermediate floor slab, the stretching of the tension member, and the like are repeated, and then the upper concrete floor slab 5 is formed. In order to protect the foamed plastic from oil and the like, a waterproof sheet or the like can be laid beforehand on the lower surface of the concrete floor slab 5 as needed.

Lastly, a roadbed material is laid on the concrete floor slab 5, and asphalt pavement and the like are performed, whereby the widening work on the sloped land is completed.

When the embankment structure of the self-supporting wall shown in FIG. 4 is constructed by the method for constructing a lightweight embankment of the present invention, similarly to the above-described example, the wall 10 is formed of steel piles and concrete panels.
a, 10b, forming the concrete foundation 15, filling the foamed plastic 1, stretching the tension member 6, stretching the intermediate floor slab 1
After the formation of No. 1 is repeated, the upper slab 12 is formed.

In this case, the tension member 6 is stretched by the wall 10a.
The tension members 6 are attached to the horizontal members spanned between the steel piles
After the tension member 6 is spread on the foamed plastic 1 and the tension member 6 is spread on the foamed plastic 1, the other end of the tension member 6 forms a wall 10 b so as to maintain the tension state. It is wound around and fixed to the horizontal member spanned between.

In the method for constructing the lightweight embankment according to the present invention described above, the method of fixing the tendon 6 is not limited to the above-described method, and may be, for example, fixed to the concrete panels forming the front wall 3 and the walls 10a and 10b. Alternatively, a plurality of fixing pins can be fixed to the back slope 2 at a time by a long member formed continuously. Further, in order to secure the tension state of the tension member 6, the tension member 6 can be supplementarily fixed to the foamed plastic 1 with a pin or the like.

[0049]

As described above, according to the present invention,
Since a planar tension member is used to enhance the stability of the structure, fixing is easy, the number of fixing points can be freely increased, and a sufficient tensile force can be easily secured. In addition, the load applied to the wall can be dispersed by the planar tension member, and local concentrated load in the structure can be avoided. Further, expensive anchor rods and anchors conventionally used for stabilizing the structure are not required. Therefore, a structurally stable lightweight embankment structure can be constructed in a shorter period of time and at lower cost.

[Brief description of the drawings]

FIG. 1 is an elevational sectional view showing an example of a structure of a widening embankment on a slope according to the present invention.

FIG. 2 is a sectional elevational view showing another example of the structure of the widening embankment on the slope according to the present invention.

FIG. 3 is an elevational sectional view showing another example of the structure of the widening embankment on the slope according to the present invention.

FIG. 4 is an elevational sectional view showing an example of an embankment structure of a self-standing wall according to the present invention.

FIG. 5 is a diagram for explaining a method of stretching a tension member.

FIG. 6 is an elevational sectional view showing a structure of a conventional widening embankment on a slope.

FIG. 7 is a vertical sectional view showing a conventional self-standing wall embankment structure.

FIG. 8 is a diagram for explaining a retaining wall earth pressure reduction method using geotextile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,101 Foam plastic 2,102 Back slope 3,103 Front wall 4,11,104,111 Intermediate floor slab 5,12,105,112 Floor slab 6 Planar tendon 7 Fixing pin 8,108 Anchor rod 9, 109 anchor 10a, 10b, 110a, 110b wall 13 steel pile (H-shaped steel) 14 horizontal member 15 concrete foundation 16 backfilling material 17 fixing pin 114 concrete retaining wall 115 back ground 116 geotextile 117 slip soil mass 118 slip surface

Claims (10)

[Claims] 1. A lightweight embankment structure, wherein a planar tendon is stretched in a structure having a structure filled with foamed plastic. 2. A foam plastic is filled between the front wall and the back slope, one end of the sheet-like tension member is fixed to the front wall, and the other end is fixed to the back slope. The structure of the lightweight embankment according to claim 1. 3. The lightweight embankment structure according to claim 1, wherein foamed plastic is filled between the walls, and both ends of the planar tendon are fixed to the walls. 4. A sheet-like tendon is embedded in a concrete slab located at the top or / and middle of the foamed plastic filling layer.
3. The structure of the lightweight embankment according to any one of 3. 5. The foamed plastic filling layer is characterized in that the sheet-like tendon is arranged between the concrete slab and the foamed plastic filling layer arranged at the top and / or middle of the foamed plastic filling layer. The structure of the lightweight embankment according to claim 1. 6. A sheet-like tendon is disposed between the foamed plastic filling layers.
The structure of the lightweight embankment according to any one of the above. 7. The sheet-like tension member is a geogrid made of a resin stretch-formed product.
The structure of the lightweight embankment according to any one of the above. 8. The method for constructing a lightweight embankment according to claim 2, wherein a horizontal member is bridged between the steel piles on a front wall constructed by attaching panels to the steel piles, and Light weight characterized in that it includes a step of fixing one end of the tendon, spreading the tendon on foam plastic or concrete slab, and fixing the other end of the tendon on the inclined back surface. Embankment construction method. 9. The method for constructing a lightweight embankment according to claim 3, wherein a horizontal member is bridged between the steel piles of each wall constructed by attaching panels to the steel piles. Fixing the one end of the tendon, spreading the tendon on foam plastic or concrete slab, and fixing the other end of the tendon to the horizontal member between the opposing steel piles. Construction method of lightweight embankment characterized by including. 10. The method for constructing a lightweight embankment according to claim 8, wherein the sheet-like tendon is a geogrid made of a stretch molded product of a resin.