JPH01310018A - Reinforcement and stabilized earth structures - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improved reinforcement materials for use in stabilized earth structures.

The technology for stabilizing earth structures by embedding mutually spaced reinforcement members in soil is well established. The basic principle of this technology is the British patent No. 1.039 by the applicant.
361@, and many structures of this type have been built all over the world. The reinforcement stabilizes the soil substantially entirely by frictional forces between the reinforcement and adjacent filler particles, and between the filler particles and the remaining filler particles. The reinforcements are spaced apart from each other so that the above-mentioned frictional forces are transmitted throughout the embankment and the tension created in the reinforcements resists the horizontal movement of the filler particles.

The tension in the reinforcing member must be strong enough to withstand the horizontal forces caused by the weight of the embankment and the loads applied on the reinforcing member, such as roads and cars. In order to maintain elastic properties in a stabilized soil structure, any form of reinforcement must be flexible so that it can make frictional contact with the embankment and allow for soil movement. There must be. If the embankment stabilized in this way is made substantially high in its vertical plane, it can be assumed that the earth and sand have certain elastic properties that are sufficiently close to each other in the vertical direction without collapsing. There was found.

An unstabilized earth block was first defined by Coulomb as α = π/4 + Φ/2 (Φ = friction angle) along the plane of the base of the block, usually about 63° with respect to the horizontal plane. It tends not to satisfy the well-known formula.

This plane-to-soil section of soil is often referred to as a "Coulomb wedge" or "active wedge." According to old construction methods, if a vertical wall was to be constructed, a relatively large wall structure had to be built in the vertical plane, primarily to prevent the wall from collapsing under the weight of the wall. Using the technique of British Patent No. 1,069.3615"3, the vertical faces of the earthen blocks need only be protected from corrosion;
Typically, relatively thin cladding elements are used at the exposed ends of the reinforcement.

Another type of stabilizing device that has been used in the past uses an anchor member buried in the soil and connected to the sheathing by a tie rod. In general, what does Dyrod do to soil? The ff1 effect was negligible, so soil was buried between the anchor member and the covering material in order to stabilize it. in this case,
Since the Coulomb wedge does not change substantially, the anchor member must be placed behind the Coulomb wedge.

The reinforcement used in the technique of GB 1.069.361 is an effective strip, but if these strips cannot exert sufficient frictional force to stabilize the soil, various forms of reinforcement may be used. can be used. Strips and other forms of reinforcement are generally buried in layers and upwards. Such earth constructions typically involve placing layers of strips spaced apart from each other within a layer of flat compacted soil, compacting the layer of arranged strip soil fill, and using such a process. Repeat this until the height of the afforestation reaches the planned height.

According to Vidal's technique, by using reinforcement,
It was found that if the soil was not stabilized, the characteristics of the embankment would change such that the boundaries of the active zone were substantially closer to the vertical plane of the soil.

Surprisingly, recent experiments have shown that the position of the boundary of the active edge, which is effectively the line of maximum tension in the reinforcement, is almost parallel to the vertical axis, except in the area close to the U section of the structure. There was found. Therefore, the boundaries of the active edge are approximately 0.28i ± 0.02H from the vertical plane for most structures.
) (II indicates the height of the structure)
.

In such structures the length of the reinforcement is always at least 0
．． 7H, this means at least 0.4 of the reinforcement length.
This means that H extends from the active wedge into the resistance band, ie, the non-collapse band. In the case of walls of low or medium height, the length of the reinforcement is usually greater than the height, i.e. 0.7H to 1.2H, so such a construction requires even more reinforcement. The portion is located within the resistance zone and simply rubs the fill sufficiently to resist movement of the stabilized active wedge. The surface area of the reinforcement in contact with the embankment is taken into account to prevent the reinforcement from being pulled out. However, although a substantial safety factor has always been taken into account, how short the reinforcing material should be placed within the active zone has not heretofore been considered.

Reinforcements have always been formed to provide a substantially uniform friction surface along their entire length. Typically the reinforcement was a stainless steel or galvanized steel strip, sometimes with transverse bars to enhance frictional contact. Considering that only 0.3H of reinforcement length is required to stabilize the active wedge, 0.3H of reinforcement length is required to stabilize the active wedge.
The remaining portion of the reinforcement extending over 4H or more serves only to hold the reinforcement to Qi in the rear zone of the active wedge, and therefore to support the rear of the reinforcement located in the retention zone. You can think of another way. By doing so, you can save on materials, leading to cost reductions. The length of the reinforcement is also related to the material of the reinforcement and the depth of the fill that must be removed and compacted to form the wall, and has a significant impact on the construction cost of the earth structure. I understand.

In any stabilized soil structure, the flexible reinforcement must have a strength of at least 0,45H1, preferably 0, to maintain the desired properties of the soil in areas except near the base of the structure. It is believed that it would have to be extended by a distance of .5H. Near the base of the structure, the length of the reinforcement is 0.35.
It is also possible to shorten it to 8, more preferably 0.4H. However, beyond a distance of 0.8H, it is believed that the reinforcement does not need to be in frictional contact with the fill, even if the wall is low.

As mentioned above, conventional reinforcements have a length of 0.71 mm or longer and have uniform properties across the length. However, if the reinforcement is to be retained in the retention zone, shorter reinforcements than those described above are used, for example reinforcements with a length of 0.65H or less, more preferably 0.5H. It turns out that it can be done. Therefore, in order to stabilize the active wedge within the active wedge, a safety factor can be used to ensure that the reinforcement and the fill are in sufficient contact with each other and that the rear side of the reinforcement is not pulled out of the retention zone. is now possible.

This can be achieved by employing Vidal's technique using reinforcement with uniform properties over its entire length, on the one hand, and a composite technique coupled with soil interaction and, on the other hand, anchor tie rod technology. It is therefore possible to form reinforcements with friction zones practically over their entire length and anchored at the ends, and such reinforcements have been used in the Vidal technique to perform various tasks. Generally shorter than flexible reinforcement.

According to the present invention, in front of the stabilized embankment,
or having a front end disposed proximate to the front surface;
A flexible reinforcement for embankment stabilization is provided having a trailing end adapted to be disposed at the rear of the embankment. Such reinforcement will interact well with the soil over its entire length. An anchor member is attached to the rear end of the stiffener.

The reinforcement can therefore be made shorter in the fore-and-aft direction than conventional reinforcement, saving on the material used for the reinforcement (usually steel) and requiring less soil to be disposed of when constructing the wall.

The friction zone of reinforcement may be of various types used in the Vidal technique, but is preferably a strip.

The material of the reinforcement may be changed.

High tensile strength materials, such as steel, are preferred, but appropriate safety precautions must be taken, such as galvanizing to prevent corrosion.

If necessary, the strips may be provided with ribs to increase their frictional interaction, as seen in British Patent No. L 563.317.

The anchor member may be made of a material that acts passively on the top, such as concrete with its plane perpendicular to the line of reinforcement.
It can be a root or something like a metal plate. In some cases,
The anchor member usually has its plane parallel to the line of reinforcement, i.e. substantially horizontal, relative to the soil. It may also be an anchor plate that provides a rubbing action to prevent movement of the anchor member. Such anchor plates may be metal or concrete and are usually rigid, as opposed to the flexible friction zones of the reinforcement.

The anchoring member may be attached directly to the end of the friction zone;
Alternatively, a tie (connection) member that does not substantially exert a frictional effect on the soil may be attached to the end thereof. In any case, it is desirable to attach the anchor member directly to the reinforcing member.

According to a further feature of the invention, a stabilized earth structure having a substantially vertical front face and a substantially horizontal reinforcement having a friction zone extending rearwardly from the front face is provided. a layer of reinforcement material to which the anchor member is attached, and a layer of compacted soil is disposed between the layers of reinforcement material to create a frictional force between the layers of reinforcement material and to create a frictional force in the friction zone. The placed soil resists the horizontal movement and generates tension in the reinforcement, which is smaller than the tension in the reinforcement H, and the anchor members are used to maintain the stability of the soil structure. An earthen structure is provided that is sufficiently resistant to uprooting.

In such ±81 structures, the maximum tension line of the reinforcement is generally substantially the same as in conventional Vidal structures, ie, about 0°3H.

In such earth structures, if the same number of reinforcements are used in each case, the F of the reinforcements used in the present invention is
The reinforcement of the present invention is shorter than the uniform type reinforcement of the conventional Vidal technology with the same frictional capacity provided by the length of the J friction zone. This reinforcement can be shorter than the non-friction type tie rods used in the anchor members described above.

This is because, in the case of this anchor member, the Coulomb wedge at least at the top of the soil structure penetrates into the heap direction to a considerable extent, so that -8 degrees of soil must be stabilized and therefore treated during construction of the wall. The space between the soil increases.

As previously pointed out, the techniques of the present invention can significantly reduce the amount of soil that must be treated, and in many cases can reduce the amount of soil that must be excavated to accommodate the wall.

The invention is particularly suitable for low or medium-height walls, for example from 4 to 15 meters in height, and also for the upper 15-metre portion of tall walls. Beyond this range, the ratio of the length of the friction zone of the reinforcing material to the wall height (-1) was conventionally 1.3:0.7. It has been found that the structure according to the invention reduces the H content by, for example, up to 50%. On the other hand, it is necessary to consider the function of a stabilized earth retaining wall as a heavy-duty wall that resists collapse. Generally l:H must not be reduced below 0.45, preferably below 0.50. The quantity of reinforcement can theoretically be varied infinitely, but in practice any earth structure has uniform dimensions and a fixed number of connection points for attachment to the reinforcement. Standard panels are used.

There is therefore a tendency to use low walls with a substantially larger ratio of L:H than in the case of high walls.

In such a case, according to the present invention, L:I+ is 0.5
, but generally [:H is not more than 0.8. In some cases I! L throughout the quaternary field:
Although H may not be the same, as long as the stability of the structure (a) body can be maintained, the ratio of the reinforcing material (b) to (b) may be small near the J part (a) of the structure.

In general, in order to obtain a sufficient mutual friction effect in the active zone, in this zone at least 2%, preferably at least 5%, of the area of the soil bed on which each layer of reinforcement is placed is covered with reinforcement material, and Preferably, there are at least four layers of such reinforcement within the structure.

A detailed description of the invention follows below with reference to the drawings.

The reinforcement shown in Figure 1 is a 60x5 galvanized
It has a front part (1) consisting of a 1M flat strip, which is connected to the anchor member (3) by bolts (2). The front end of the reinforcement is covered with concrete covering material (6
) is fixed by another bolt (4) to a tab (5) embedded in the hole.

If the reinforcement is to be used in a wall section with a height of 10.5 meters, [:■ is 05, so that in such a structure the length of the front part (1) is approximately 5.25 meters. Considering the pullout resistance, the resistance provided by the anchor member and the strip is equal to the total length, i.e. 5.25
The resistance force is equivalent to that obtained by a high adhesion type strip with two ribs in meters. The total length of two such strips is therefore 2 x 5.25 meters. Therefore, steel materials can be saved by approximately 100%. Viewed from another point of view, the reinforcement according to the invention corresponds to a strip of the 171st ribbed high-adhesion type with a length of about 8 meters, which requires a deeper embankment and thus increases costs. I can understand that.

In the reinforcement shown in FIG. 2, the strips are identical in size to those shown in FIG. 1, but the anchor members (3) are now flat anchor braids (3').

In the wall shown in FIG. 3, the line (1) is the reinforcement according to the invention (
This is the line connecting the maximum FJ drift points of 8). Reinforcement material (8)
The anchor member (9) attached to is shown on the back side of the wall. Line (10) is a line indicating the position of the end of a conventional stiffener made of the same material as the front part of the stiffener of the invention (the number and spacing of the stiffeners are the same). The line (7) connecting the points of maximum friction is almost the same in both the conventional case and the present invention.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of a reinforcing material according to the present invention. FIG. 2 is a plan view of another embodiment of the reinforcement according to the invention. FIG. 3 is a schematic cross-sectional view of a stabilized earth structure according to the invention. 1...Front 5...Tab 2
．． 4... Bolt 6... Covering material 3
・・・・・・Anchor member

Claims (9)

[Claims] (1) A flexible reinforcement for soil stabilization having a front end located near the front of the stabilized embankment and a rear end located at the rear of the embankment, and which provides support to the soil along its entire length. A reinforcing member having a friction zone capable of exerting a sufficient frictional action and having an anchor member at its rear end. (2) A reinforcing material according to claim 1, wherein the anchor member is a plate, and the plane of the plate is perpendicular to the line of the reinforcing material. (3) The reinforcing material according to claim 1, wherein the anchor member is a plate and is parallel to the line of the planar reinforcing member of the plate. (4) A reinforcing material according to any one of claims 1 to 3, characterized in that the anchor member is directly connected to an end of the friction zone. (5) A stabilized earth structure having a substantially vertical front surface with a substantially horizontal reinforcement having a friction zone extending rearwardly from the front surface and having an anchor member attached to the rear end thereof. a layer of compacted soil is placed between the layers of reinforcement to create a frictional force between the layers of reinforcement, and the soil placed in the friction zone is moved horizontally. The anchoring member is attached to an earth structure that has sufficient resistance to pull-out to maintain stability of the earth structure and to create a tension in the reinforcement that is less than the tension in the reinforcement. body. (6) The stabilized earth structure according to claim 5,
L: Earth structure where H is lower than 0.8, L is the length of the reinforcement and H is the height of the earth structure. (7) A stabilized earth structure according to claim 5 or 6, characterized in that the earth structure has a height of 4 to 1.5 meters. (8) A stabilized earth structure according to any one of claims 5 to 7, wherein at least 2% of the area of the soil bed in which each layer of reinforcement is located in the friction zone of the reinforcement.
an earthen structure, characterized in that it is covered with said reinforcing material and four layers of such reinforcing material are arranged. (9) The stabilized earth structure according to any one of claims 5 to 8, characterized in that it has the flexible reinforcing material according to any one of claims 1 to 4. .