JP2004116093A - Structure and its construction method by light-weight foam mixed earth method - Google Patents

Abstract

In a structure using a lightweight foam mixed soil method, a crack is prevented from being generated in a lightweight embankment 5 which is a lightweight foam mixed soil. In addition, when the lightweight mixed air bubble soil is not cured, the lateral pressure acting on the retaining wall 10 is reduced.
A layer (20, 20a, 20b) made of a resin foam is formed between an inner surface of a retaining wall 10 and a lightweight embankment 2 made of a lightweight mixed air bubble in a state of being in close contact with the inner surface of the retaining wall 2. I do. Preferably, a foamed resin sheet 30 functioning as a heat insulating layer is disposed between the resin foam layer and the lightweight embankment. In addition, a concrete layer 21 is arranged as a weight on the resin foam layer.
[Selection diagram] Fig. 4

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a structure using a lightweight foam mixed soil method and a construction method thereof, and in particular, to a structure capable of effectively preventing a crack from being generated in a lightweight embankment formed by the lightweight foam mixed soil and its construction. About the method.
[0002]
[Prior art]
BACKGROUND ART A FOAMED CEMENT BANKINB-FCM method is known. Aerated lightweight mixed soil is a fluid material made by mixing cement, raw soil, and water at an appropriate ratio and blending the required amount of air bubbles. Or between a wall panel and the ground, between a retaining wall standing on the ground, and between the retaining wall and the ground, and the like. The cast lightweight lightweight mixed soil hardens into a lightweight embankment, and a pavement or the like is applied on the lightweight embankment to construct a structure using the lightweight lightweight mixed soil construction method (for example, Patent Documents 1 and 2; 3 etc.).
[0003]
In the case of a retaining wall, it may be a flat plate like an ordinary earth retaining wall, or may be an abutment 10 having a footing 11 which spreads to the side at the bottom like a bridge (see FIG. 8). In the example shown in FIG. 8, the bridge 1 is attached to the left side of the abutment 10, and the ground embankment 2 is on the left side. The abutment 10 is fixed to the ground 3 so that the footing portion rides on the foundation pile 4 built in the ground 3. A lightweight lightweight mixed soil is poured into the space S between the abutment 10 and the ground embankment 2 and hardens to form the lightweight embankment 5. A pavement 6 and the like are constructed on the formed lightweight embankment 5. Immediately after casting, the light-weight foamed mixed soil has fluidity and generates a side pressure, but after hardening, becomes self-supporting, so that the side pressure is reduced. Therefore, structures such as a formwork, a wall panel, and a retaining wall can be simplified to some extent (for example, see Non-Patent Document 1).
[0004]
In a structure using the lightweight lightweight mixed soil method, for example, when using the abutment 10 erected on the ground 3 as a retaining wall, the abutment 10 is not self-supporting until the poured lightweight lightweight mixed soil hardens, and the fluid pressure is applied to the abutment 10. In addition, a downward load is applied when the embankment 5 is placed on the footing 11 of the abutment 10. As a result, unevenness or the like occurs on the road surface, and a crack K may occur between the embankment 2 and the abutment 10, as shown in FIG. In order to avoid this, as shown in FIG. 9, it has been reported that it is effective to arrange a resin sheet 8 such as a foamed polystyrene sheet as a joint material outside the footing (Non-Patent Document 2). In FIG. 9, reference numeral 7 denotes a stepping plate arranged as needed.
[Patent Document 1]
JP-A-10-131191 [Patent Document 2]
Japanese Patent Application Laid-Open No. 2000-178085 [Patent Document 3]
JP-A-2002-188148 [Non-Patent Document 1]
Pamphlet of "FCB Method Using Bubble-Mixed Lightweight Soil"-Japan Highway Public Corporation Testing Laboratory Earthworks Testing Laboratory, P5
[Non-patent document 2]
"Guideline on Design and Construction of Lightweight Embankment Method Using Bubble-Mixed Lightweight Soil", March 1996, Japan Highway Public Corporation Testing Laboratory, Earthwork Testing Laboratory, P.S. 35-38
[0005]
[Problems to be solved by the invention]
In the structure shown in FIG. 8, as shown in FIG. 9, by arranging the resin sheet 8 as a joint material, it is possible to effectively suppress the occurrence of cracks in the lightweight embankment 5 which is a lightweight mixed air bubble. Can be. However, the load due to the lightweight embankment 5a placed on the footing 11 is still applied to one footing 11, and for some reason (for example, an unexpectedly large vertical or horizontal force acts on the abutment due to an earthquake or the like). The balance may be lost and the abutment 10 may fall down to the mountain side. It is not easy for the joint material to completely absorb such behavior of the abutment, which may cause cracks in the lightweight embankment.
[0006]
Even when the retaining wall is not an abutment with a footing but a flat plate like an earth retaining wall, it usually has a base part with some width, and the action of the lightweight embankment on that part Is also expected to cause similar behavior.
In any case, when the lightweight mixed foam is in a fluidized state, side pressure directly acts on the inner surface of the retaining wall, so it is necessary to carefully carry out concrete foundation work on the retaining wall.
[0007]
The present invention has been made in view of the above circumstances, even when an unexpected force greater than the design value acts on the retaining wall, suppresses the occurrence of the behavior of falling over the retaining wall, thereby, It is another object of the present invention to provide a structure using a lightweight lightweight mixed soil method and a construction method thereof, which can prevent the occurrence of cracks on a road embankment and lightweight embankment which is a lightweight lightweight mixed soil. Another object of the present invention is to provide a structure using a lightweight lightweight mixed soil construction method and a method of constructing the lightweight lightweight mixed soil soil, in which the lateral pressure acting on the retaining wall can be reduced when the lightweight lightweight mixed soil is uncured. .
[0008]
[Means for Solving the Problems]
The structure according to the present invention is a structure based on the lightweight foam mixed earth method including at least a retaining wall erected on the ground and an embankment formed of the lightweight lightweight mixed soil. A layer made of a resin foam is formed in a state close to the inner surface of the retaining wall.
[0009]
In the above structure, a layer made of a resin foam, which is lightweight and has a lower specific gravity than the hardened lightweight mixed soil, is closely located on the inner surface side of the retaining wall. It is on the base. For this reason, there is no significant difference in the force acting downward on the outer surface side and the inner surface side of the retaining wall, and the behavior of the retaining wall falling down to the mountain side is suppressed. The lightweight embankment made of the lightweight mixed foam will face the inner surface of the retaining wall via the resin foam layer. However, in addition to the fact that the retaining wall itself is unlikely to fall down to the mountain side, in addition to the inner surface of the retaining wall, Since the resin foam layer located in close contact with the base material can also function as a joint material made of a conventional foamed resin sheet, it is possible to prevent cracks from being generated in the lightweight embankment. In addition, the resin foam layer also has a function of reducing the lateral pressure acting on the retaining wall when the lightweight lightweight mixed soil is uncured, so that the foundation construction of the retaining wall can be simplified.
[0010]
In the present invention, the retaining wall may be a flat plate like a normal earth retaining wall, but the present invention functions particularly effectively when the abutment has a wide footing. That is, in the case of an abutment provided with a footing, if the embankment material is put on only one footing, the left-right balance is lost and a large overturning moment acts. According to the present invention, a lightweight resin foam layer is placed on at least the footing, and the overturning moment is smaller and the balance between the left and right sides is stable as compared with the above. For this reason, it is possible to effectively prevent cracks from being generated in the lightweight embankment, as compared with the structure using the light-weight lightweight mixed earth method using the conventional abutment.
[0011]
In the present invention, the type of the resin foam used to form the layer made of the resin foam is not particularly limited. Examples thereof include a polystyrene resin foam, a polyethylene resin foam, a polypropylene resin foam, and a polyester. Such as a resin foam. Polystyrene-based resin foams are particularly preferred for reasons of buffering property, moldability, water resistance and economy. In addition, it is effective to form a resin foam layer by stacking block-shaped resin foams in multiple stages from the viewpoint of ease of construction. In the present invention, for example, a retaining wall made of concrete can be formed later by using the resin foam layer as a mold. Also in this case, it is effective to form a resin foam layer by stacking block-shaped resin foams in multiple stages. In addition, what is necessary is just to use the thing currently used by this kind of conventional construction method as a bubble lightweight mixed soil.
[0012]
In the present invention, a resin foam layer is formed along the inner side surface of the retaining wall, and thereafter, a lightweight mixed foam is cast on site. When the foamed lightweight mixed soil is hardened, the temperature becomes about 80 ° C. to 100 ° C. due to the reaction heat of the concrete, and the internal moisture becomes steam. Due to the heat and steam, when the resin foam layer is a polystyrene resin foam, the resin on the surface is hardened, tertiary foamed, contracted, or hollowed out, and the heat is trapped therein. Cracks may occur due to melting of the resin exceeding 100 ° C.
[0013]
In order to avoid such a situation, in the structure according to the present invention, preferably, a foamed resin sheet functioning as a heat insulating layer is disposed between the layer made of the resin foam and the lightweight embankment. The foamed resin sheet may be any foamed resin sheet having heat insulation properties, moderate buffering properties, and heat resistance to reaction heat, and may be a polyethylene-based resin foam, a polypropylene-based resin foam, a PET foam, or a rigid urethane foam. Body, phenolic resin foam, epoxy resin foam and the like. Such a foamed resin sheet is attached to a side surface of the resin foam layer by an appropriate means.
[0014]
In the present invention, when the resin foam layer is composed of resin foam blocks stacked in multiple stages, buoyancy is generated by the cast uncured air-cell lightweight mixed soil, and there is a possibility that the stacked blocks may be displaced or collapsed. is there. In order to avoid this, in the structure according to the present invention, it is preferable that a horizontal portion having a required thickness (for example, about 100 mm to 150 mm) is provided at an appropriate position in the vertical direction of the stacked resin foam blocks (for example, at intervals of about 1 m). The concrete layer spreading in the direction is formed as a weight. Since the lifting of the block is suppressed by the weight of the formed concrete layer, stable construction can be performed.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on embodiments with reference to the drawings. FIGS. 1 to 4 illustrate a structure using a light-bubble lightweight mixed earth method according to the present invention, together with its construction procedure. In the structure of this embodiment, the abutment 10 is used as a retaining wall, as in the cases shown in FIGS. 8 and 9, and the bridge 1 is attached to the left side of the abutment 10 in the figure, and the ground embankment 2 is on the left side. ing. The abutment 10 has a footing 11 having a required width (for example, about 2000 mm) at the bottom, and is fixed to the ground 3 so that the footing portion rides on the foundation pile 4 built in the ground 3. I have.
[0016]
After the abutment 10 as a retaining wall is thus formed, a resin foam 20a such as a block-shaped polystyrene resin foam (EPS) is stacked on the footing 11 on the mountain side in multiple stages to a predetermined height (FIG. 1). Concrete is poured into a thickness of about 100 mm to 150 mm on the stacked resin foams 20a, and curing is awaited (FIG. 2). The concrete layer 21 functions as a weight for the resin foam 20a of the lower layer, and when the light-weight foamed mixed soil is cast, the block-shaped resin foam 20a is formed by the buoyancy generated by the uncured light-weight mixed foam. Prevents lifting.
[0017]
After the poured concrete has hardened, as shown in FIG. 3, the block-shaped resin foam 20b is again stacked on the concrete layer 21 to a predetermined height. If necessary, a step board 7 is mounted thereon. The weight of the stepping plate 7 prevents the block-shaped resin foam 20b from floating. The “layer made of resin foam” according to the present invention is formed by the stacked block-shaped resin foams 20 a and 20 b in a state of being closely contacted with the inner surface of the abutment 10. Although only one concrete layer 21 is shown in the figure, two or more concrete layers 21 are formed according to the height of the abutment 10. At that time, it is desired to form the concrete layer 21 at every height of about 1 m of the block-shaped resin foam to be stacked.
[0018]
For example, a heat insulating sheet 30, which is a polyethylene-based resin foam sheet, is attached to the entire side surface of the formed “layer made of resin foam” on the mountain side. The thickness of the heat insulating sheet 30 may be about several mm to 20 mm, depending on the degree of heat insulating performance of the sheet. After or in parallel with the attaching operation of the heat insulating sheet 30, the lightweight lightweight mixed soil is poured into the space S surrounded by the “layer made of resin foam” and the ground 2. . Usually, the casting is carried out to a depth of about 1 m and the hardening thereof is waited. After the hardening, the casting is repeated thereon, and the lightweight mixed soil is filled to a required height. The lightweight mixed foam is hardened to form the lightweight embankment 5.
[0019]
Reaction heat is generated when the light-weight foamed mixed soil is cured, but heat transfer to the “layer made of resin foam” is prevented by the heat insulating sheet 30, so that the resin foam is tertiarily foamed. Does not occur. In addition, the lifting of the block-shaped resin foam 20a due to the buoyancy generated by the uncured cellular light-weight mixed soil is also prevented by the weight of the concrete layer 21. Thereafter, by performing the required construction of the surface pavement 6 and the like, the structure of the present invention based on the lightweight mixed soil method is completed.
[0020]
FIG. 5 shows another embodiment of the structure according to the present invention. In this example, flat retaining walls 10a, 10a are erected using concrete foundations 4a, 4a constructed with a predetermined width on the ground 3, and a space between the left and right retaining walls 10a, 10a. A lightweight lightweight mixed soil is cast in S to form a lightweight embankment 5, on which a pavement 6 is formed to form a road. Also in this case, the “layer made of resin foam” (the block-shaped resin foam 20a, 20b) is closely attached to the inner side surface of each of the retaining walls 10a, 10a in the same manner as shown in FIGS. A concrete layer 21 is formed between the block-shaped resin foams 20a and 20b, and a heat insulating sheet 30 is formed on the inner surface of the “layer made of resin foam”. . In FIG. 5, reference numerals 51 and 52 denote waterproofers, and 53 denotes an L-shaped retaining wall for defining the width of the road.
[0021]
In the present invention, when the required stability required for the structure is ensured, the above-mentioned “concrete layer 21” and / or “heat insulating sheet 30” can be omitted. FIG. 6 is a construction example in which the “concrete layer 21” is omitted, and the “layer made of resin foam” is formed by continuously stacking the block-shaped resin foams 20 to a required height. FIG. 7 is a construction example in which both the “concrete layer 21” and the “insulating sheet 30” are omitted, and the inner surface of the “layer made of resin foam”, which is the block-shaped resin foam 20, is lightweight. It is in direct contact with the embankment 5.
[0022]
Although not shown, in the structure shown in FIGS. 1 to 4, after forming the footing 11, a “layer made of a resin foam” is formed, and concrete is formed by using the layer as a mold. The retaining wall of the abutment 10 may be formed by casting. In the construction of the structure as shown in FIG. 5, a "layer made of resin foam" may be formed first, and the retaining wall 10a may be formed by using the layer as a mold. . The subsequent steps are the same as in the other embodiments.
[0023]
【The invention's effect】
As described above, according to the present invention, it is possible to effectively prevent cracks from being generated in the lightweight embankment, which is the lightweight lightweight mixed soil, in the structure using the lightweight lightweight mixed soil construction method. Further, since the lateral pressure acting on the retaining wall can be reduced when the cellular lightweight mixed soil is not cured, the construction of the retaining wall can be simplified.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a first diagram illustrating a structure using a light-weight lightweight mixed earth method according to the present invention, together with a construction procedure.
FIG. 2 is a view for explaining a construction procedure following FIG. 1;
FIG. 3 is a diagram illustrating a construction procedure following FIG. 2;
FIG. 4 is a view for explaining a construction procedure following FIG. 3 and shows a completed structure.
FIG. 5 is a diagram showing another embodiment of the structure by the light-weight mixed air-built earth method according to the present invention.
FIG. 6 is a view showing still another embodiment of the structure obtained by the light-weight and lightweight mixed earth method according to the present invention.
FIG. 7 is a view showing still another embodiment of the structure using the light-weight and lightweight mixed earth method according to the present invention.
FIG. 8 is a diagram showing an example of a structure obtained by a conventional light-weight and lightweight mixed earth method.
FIG. 9 is a view showing another example of a structure obtained by a conventional light-weight and lightweight mixed earth method.
[Explanation of symbols]
10: Abutment as retaining wall, 11: Footing portion of abutment, 20, 20a, 20b: Layer made of resin foam (block-shaped resin foam), 21: Concrete layer, 30: Foam resin functioning as heat insulating layer Seat, 1 ... Bridge, 2 ... Ground embankment, 3 ... Ground, 5 ... Lightweight embankment, 6 ... Pavement

Claims (6)

In a structure based on the lightweight lightweight mixed soil method, which includes at least a retaining wall erected on the ground and an embedded lightweight lightweight mixed soil, a retaining wall is provided between the inner surface of the retaining wall and the lightweight embedded lightweight lightweight mixed soil. A structure, wherein a layer made of a resin foam is molded in a state of being in close contact with the inner side surface. The structure according to claim 1, wherein the retaining wall is an abutment having a footing, and the layer made of a resin foam is disposed at least on the footing. The structure according to claim 2, further comprising a foamed resin sheet functioning as a heat insulating layer between the resin foam layer and the lightweight embankment. 4. The method according to claim 1, wherein the resin foam layer is composed of resin foam blocks stacked in multiple stages, and a concrete layer extending in the horizontal direction is formed at an appropriate position in the vertical direction. Or the described structure. After erecting a retaining wall on the ground, a lightweight lightweight mixed soil was cast in the space surrounded by the ground and the retaining wall or in the space surrounded by the retaining wall and the retaining wall to form a lightweight embankment. In the construction method of the structure by the lightweight foam mixed earth method, at least a step of arranging a layer made of a resin foam on the inner side surface of the retaining wall as a step before casting the lightweight lightweight mixed soil, A construction method characterized by casting lightweight lightweight mixed soil to form a lightweight embankment. After erecting a retaining wall on the ground, a lightweight lightweight mixed soil was cast in the space surrounded by the ground and the retaining wall or in the space surrounded by the retaining wall and the retaining wall to form a lightweight embankment. In the construction method of the structure using the lightweight foam mixed soil method, as a process before casting the lightweight lightweight mixed soil, a process of forming a layer made of resin foam and using it as a formwork to construct a retaining wall And then forming a lightweight embankment by pouring light-weight foamed mixed soil.

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