JPH11152732A - Culvert-burying structure by using waste tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a relieve effect for a vertical earth pressure exerted on the top plate of a culvert and to reduce material cost for reduction of the vertical earth pressure. SOLUTION: After a work for a culvert 10 is executed, a number of waste tires 20 are laid on a top plate 11, and side earth shield plates 40 are erected on both sides thereof. Upper earth shield plates 30 are laid above waste tires 20, and by scattering a fill material after covering with an engineering sheet 50 and carrying out rolling compaction, a given height filling ground in which the culvert 10 is buried is formed. When, at a process of land formation, upper loading from a filling ground material has reached a given value, the tire 20 is buckled and the height thereof is rapidly decreased. Thereby, a ground arch GA is formed including a projected underground discontinuous surface rising upward from the two edges in the width direction of the top plate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for reducing earth pressure on a culvert under an embankment used for a waterway or a road.

[0002]

2. Description of the Related Art A culvert is a concrete sewer buried in an embankment such as a road or embankment for water, drainage, or a waterway. A culvert (box culvert) 1 shown in FIG. 6 extends in a direction orthogonal to the illustrated cross section, is constructed of cast-in-place concrete or precast concrete, and is buried in the embankment G.
When the cover height of the embankment material on the culvert 1, that is, the height of the upper embankment laid on the culvert 1 is large, in order to reduce the earth pressure acting on the top plate 1 a of the culvert 1, Conventionally, on the top plate 1a,
For example, after laying a pressure receiving plate 2 of a required thickness made of a flexible material having a predetermined yield strength, such as styrene foam, the embankment work is performed.

The pressure receiving plate 2 made of polystyrene foam or the like has a function of reducing the Marston earth pressure on the top plate 1a of the culvert 1 by its compressibility. That is, when the pressure receiving plate 2 is not laid, since the layer thickness of the embankment located directly above the culvert 1 is smaller than the thickness of the surrounding embankment, the amount of consolidation settlement during compaction is reduced, and as a result, A large Marston earth pressure due to compaction pressure acts on the top plate 1a of the culvert 1,
When the pressure plate 2 is laid, the settlement of the embankment directly above it follows the consolidation settlement of the surrounding ground due to its compressive deformation,
Thereby, the Marston earth pressure can be effectively absorbed.

Secondly, the pressure receiving plate 2 has a function of reducing the vertical earth pressure on the top plate 1a of the culvert 1 by forming a ground arch on the upper embankment G. That is, in the burying work of the culvert 1, the embankment material is successively compacted and compacted every time the embankment material is laid up by a predetermined spreading thickness, but the overload F by the upper embankment G of the culvert 1 causes the pressure receiving plate 2 to yield. At the time when the stress is exceeded, the pressure receiving plate 2 is rapidly plastically deformed in the compression direction from the original state shown by the dashed line in FIG. As a result of the redistribution, as shown by a broken line in the figure, a ground arch GA formed of an upwardly projecting underground discontinuous surface rising from both sides in the width direction of the top plate 1a is formed. Therefore, the overlaid load due to the height of the upper embankment G is the ground arch GA.
Of the culvert 1, the vertical earth pressure acting on the top plate 1a of the culvert 1 is effectively reduced.

[0005]

The following problems are pointed out according to the buried structure of the culvert in the above-mentioned prior art. (1) The pressure receiving plate 2 made of styrene foam or the like has a small thickness reduction due to compression yield deformation, and therefore, the ground arch GA
It is difficult to secure a large cavity for forming the hole. (2) When the height of the embankment is large, it is necessary to use a large amount of the pressure receiving plate 2 to form a ground arch with a large cavity, so that the material cost increases.

SUMMARY OF THE INVENTION The present invention has been made under the above circumstances, and the technical problem thereof is to improve the effect of reducing the vertical earth pressure acting on the top plate of the culvert, and to improve the vertical earth pressure. An object of the present invention is to make it possible to reduce the cost of materials as mitigation means.

[0007]

Means for Solving the Problems As a means for effectively solving the above-mentioned technical problems, a culvert burying structure according to the present invention comprises a top plate of a culvert buried in an embankment and a top plate on the culvert. A large number of discarded tires, in which the buckling strength of the outer crown portion is smaller than the overburden load caused by the final height of the upper embankment, are laid between the upper embankment to be erected and the shaft center in a substantially vertical direction. And
An earth and sand shielding plate is laid on the waste tire. In addition, the waste tire mentioned here is a tire from which the rim has been removed, and in the case of having a tube, the tube has also been removed.
In addition, the final construction height refers to the height to the top of the embankment when the construction is completed.

[0008] In the present invention, the discarded tire laid on the top plate of the culvert with its axis centered in a substantially vertical direction, the upper load from the upper embankment laid on the disc is transferred to the outer crown portion (for automobiles). At the ground surface when installed). And since this crown portion has a smaller buckling strength than the overburden load due to the final construction height of the embankment ground, the overburden load on the culvert exceeds the buckling strength during the embankment creation process of the upper embankment ground. As it increases, the crown buckles at that point. Because the waste tire is hollow, buckling significantly reduces its axial width, thus creating a large cavity in the ground directly above it, forming a significant ground arch due to redistribution of ground stresses. . After that, the upper embankment is further erected and formed to the final formation height, but the further increasing overload is insulated at the ground arch, so the vertical earth pressure acting on the top plate of the culvert is effective. To be reduced.

[0009] When the final height of the upper embankment pile on the culvert is relatively high, it is effective to stack a plurality of discarded tires vertically. In this case, since the cavity formed by the buckling of the plurality of waste tires becomes large, underground stress redistribution is likely to occur, and a ground arch having a significant underground discontinuity is formed. Also, in this case, assuming that the buckling strength of the crown portion is different for each tire in each step, the tire in the step having the relatively smaller buckling strength buckles in the embankment forming process to form a ground arch, Even if the ground arch collapses for some reason, the tire of the step having the higher buckling strength buckles and the ground arch can be regenerated.

[0010] When earth and sand enter the hollow portion of the waste tire and between adjacent waste tires and are deposited in the process of forming the embankment, the crown portion is reinforced by the deposited soil and becomes less likely to buckle. Preferably, a sediment shielding plate for preventing intrusion of earth and sand is laid on the waste tire.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing a process of forming an embankment in a first preferred embodiment of a buried culvert structure according to the present invention. In FIG. 1, reference numeral 10 denotes a culvert which is a concrete culvert having a substantially rectangular or square cross section, and 20 denotes three rows in the longitudinal direction of the culvert 10 with the axial center on the top plate 11 of the culvert 10 being substantially vertical. A tire 30 (hereinafter simply referred to as a tire) laid on the tire 20, an upper sediment shielding plate 30 made of plywood laid on the tire 20 in order to prevent intrusion of earth and sand from above, and 40 a width on the top plate 11 A side earth and sand shield plate 50 made of a metal plate erected to prevent intrusion of earth and sand from the side along both edges in the direction, 50 is the upper earth and sand shield plate 3.
It is a civil engineering sheet laid so as to cover the tire 20 via the zero and side earth and sand shielding plate 40. Side earth and sand shield plate 40
A small hole 41 for drainage is opened at a predetermined interval in the lower part of the box.

That is, first, a precast concrete product formed into a hollow shape as shown in FIG. 1 by placing a concrete in place or in a factory in advance is placed at a predetermined position in the embankment, and connected in the longitudinal direction. The culvert 10 is constructed by going. After the construction of the culvert 10, the embankment material is scattered on both sides of the culvert 10, and the embankment is formed while compacting with a compactor. However, before the upper side of the top plate 11 of the culvert 10 is covered with the embankment material, Tires 20 are laid on the top plate 11, side earth and sand shielding plates 40 are erected on both sides thereof, and the side earth and sand shielding plates 40,
The upper earth and sand shielding plate 30 having a width capable of being inserted between the spaces 40 is placed, and the civil engineering sheet 50 is further covered. In addition, the plywood as the upper earth and sand shielding plate 30 and the civil engineering sheet 50 are sufficient as the waste material.

The tire 20 is made of rubber, as is well known, and as shown in FIG. 2, a thick crown portion 21 on the outer periphery serving as a ground contact surface, and an inner circumferential side from both sides in the axial direction of the crown portion 21. Side walls 22, 22 extending outward and bulging outward
And the entire inner periphery of the annular space S from which the rim has been removed is opened 20a. Therefore, when a load F in the axial direction is applied to the tire 20, first, the two side surfaces 2
After bending of the crowns 2 and 22, the crown portion 21 receives an increasing load F in the compression direction. And the load F
When the diameter exceeds a predetermined size, the crown portion 21 buckles and bends into a bent shape protruding toward the outer peripheral side, so that the axial width W (height) of the tire 20 is significantly reduced. And, as the tire 20 to be spread on the top plate 11 of the culvert 10, the buckling strength of the crown portion 21 is appropriately smaller than the final loading height due to the final formation height to the embankment upper surface acting per tire. Selected.

The crown 2 of the adjacent tire 20
When the crown portions 1 are in contact with each other, when the crown portion 21 buckles in a bent shape convex toward the outer peripheral side, it interferes with each other and reinforces each other, so that it is difficult for the crown portion 21 to buckle. Are not in contact with each other.

After the civil engineering sheet 50 is laid, the embankment material is also scattered thereon to cover the earth as shown in FIG. 3, and the embankment is scattered at a predetermined layer thickness and rolling is repeated. , And build a prosthetic ground of a predetermined height. At this time, the embankment ground Ga laid directly above the tire 20
Can be settled following the surrounding embankment Gb by appropriately bending each tire 20, whereby the Marston earth pressure acting on the top plate 11 of the culvert 10 when compacting the embankment is effective. Is absorbed by The permeated water in the embankment that has entered the tire laying space between the top plate 11 and the upper earth / sand shield plate 30 due to rainfall or the like is discharged from the small holes 41 of the side earth / sand shield plate 40.

The overburden load (vertical earth pressure) acting on the tire 20 increases in proportion to the embankment height of the embankment material above it. As described with reference to FIG. 2, the crown portion 21 of each tire 20 buckles and is crushed. Therefore, as shown in FIG. 4, the crown portion 21 of the tire 20 rises from the vicinity of both widthwise edges of the top plate 11 as shown in FIG. A ground arch GA composed of an underground discontinuous surface convex upward is formed. For this reason, culvert 1
The vertical earth pressure acting on the zero top plate 11 is effectively reduced.

In the case of a high embankment in which the height of the upper embankment laid on the culvert 10 is relatively high, as shown in the second embodiment of the present invention in FIG. Tire 20A is laid, and tire 20B is laid on top of it. Tire 20B is laid on both sides of the tire 20A, and a side earth and sand shield plate 40 having a height of two steps is provided on both sides thereof. And cover the civil engineering sheet 50. A plate 31 may be interposed between the lower tire 20A and the upper tire 20B.

According to the second embodiment, when the buckling strength of each of the tires 20A, 20B is substantially the same, the upper and lower tires 20A, 20B are laid in the process of laying the upper embankment.
Since both B buckle, a remarkable ground arch which is hard to disappear even when the upper embankment is large and consolidation sinks can be formed. Of course, in some cases, three or more tires 20 may be stacked.

By the way, the ground arch GA once formed in the ground in the above process maintains the effect of reducing the vertical earth pressure on the top plate 11 of the culvert 10 as long as its soundness is maintained. The large ground arch GA may be loosened due to, for example, an earthquake or an increase in infiltration water due to heavy rain, various vibrations transmitted from the embankment, and collapse due to a rolling load in the process of forming the upper embankment. In such a case, the underground discontinuity surface due to the ground arch disappears, and the insulating property against the overload is impaired, so that the effect of reducing the earth pressure acting on the top plate 11 cannot be obtained. Therefore, in order to deal with such a case, it is effective to make the buckling strengths of the crown portions 21 of the lower tire 20A and the upper tire 20B different from each other in FIG.

That is, in this case, in the process of building the upper embankment, if the overburden height increases and the overburden load increases, the upper and lower two-tiered tires 20A, 20A will eventually be formed.
B has a relatively smaller buckling strength and buckles, and the first ground arch is formed in the ground on the upper side. For this reason, even if the above-mentioned load increases by raising the embankment further higher afterwards, since this load is effectively insulated by the ground arch, the vertical earth pressure acting on the top plate 11 of the culvert 10 is reduced. It is reduced. If the ground arch collapses due to any of the above-described causes, the tire having a relatively large buckling strength buckles under the increased overload due to the collapse. Therefore, the ground arch is formed again through the process of forming a large cavity in the upper embankment, and the effect of reducing the earth pressure on the top plate 11 of the culvert 10 is maintained.

In recent years, tires that have been worn away and discarded due to long-term (long-distance) running of automobiles have become increasingly serious in terms of disposal problems due to their large amount of disposal. Is used in large quantities as a means for reducing the vertical earth pressure on the culvert 10, so that it is possible to contribute to solving the disposal problem, and it is possible to procure it at low cost, so that the material cost is reduced.

[0022]

According to the buried structure of the culvert according to the present invention, the following effects are realized. (1) The discarded tire used as the vertical earth pressure reduction means for the culvert has a significantly reduced volume when buckled, so a remarkable ground arch is formed in the ground,
The reliability of the effect of reducing the vertical earth pressure is enhanced. (2) The use of discarded tires as a means of reducing vertical earth pressure on culverts can contribute to solving the problem of tire disposal. (3) The use of discarded tires as means for reducing vertical earth pressure on culverts can reduce material costs. (4) By laying different types of discarded tires in a plurality of steps, once the formed ground arch collapses, it can be immediately regenerated and the earth pressure reducing effect is maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional perspective view showing an embankment forming process in an embodiment of a buried structure of a culvert according to the present invention.

FIG. 2 is a cross-sectional view showing the waste tire used in the embodiment cut along a plane passing through its axis.

FIG. 3 is a cross-sectional view showing the above-described embodiment cut along a plane perpendicular to the longitudinal direction of the culvert.

FIG. 4 is a sectional view showing a formation state of a ground arch according to the embodiment.

FIG. 5 is a cross-sectional view showing another embodiment of the buried structure of the culvert according to the present invention, cut along a plane perpendicular to the longitudinal direction of the culvert.

FIG. 6 is a sectional view showing a buried structure of a culvert according to the related art.

FIG. 7 is a cross-sectional view showing a state of formation of a ground arch according to the conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Culvert 11 Top plate 20, 20A, 20B Discarded tire 30 Upper earth and sand shielding plate 40 Side earth and sand shielding plate

Claims (4)

[Claims] 1. A buckling strength of a crown portion on an outer periphery between a top plate of a culvert buried in an embankment and an upper embankment laid on the culvert according to the final height of the upper embankment. A culvert burying structure using discarded tires, wherein a large number of discarded tires smaller than the load are laid with their axial centers oriented substantially vertically. 2. The buried culvert structure using waste tires according to claim 1, wherein a plurality of waste tires are stacked one above the other. 3. The buried structure of a culvert using a waste tire according to claim 1, wherein a sediment shielding plate is laid on the waste tire. 4. The burying of culverts using waste tires according to claim 2, characterized in that the waste tires laid one on another in a plurality of layers vertically have different crown buckling strengths for each step. Construction.