JP2673153B2 - Earth bolt reinforcement method - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a ground bolt reinforcing method for reinforced ground in advance before ground cutting work such as residential land preparation and slope preparation. .

"Prior Art" Normally, the slope of a cut slope formed by cutting a slope of a natural ground is almost determined by the soil condition of the original ground. For example, if the soil is clayey, the slope is 1: 1.
It is about 1: 1.2. Therefore, when constructing the cut slope with a steep slope, after cutting at a slope of 1: 1, by providing protective means such as a block retaining wall and a leaning retaining wall on the cut surface, The method of securing the steep slope of the cut slope is adopted.

If the ground soil has sufficient strength, a method of protecting the steep cut slope by mortar spraying is used instead of providing a retaining wall or other protective means on the cut surface. There is. Furthermore, even if the soil has sufficient strength, if the cut height is to be made higher, spraying the mortar alone will ensure the stability of the soil as a whole, such as slippage of slopes. Since it is difficult to do so, the so-called anchor construction method is used to secure the stability of the soil by inserting reinforcing bars into the soil.

"Problems to be solved by the invention" However, in the former method, costs such as block loading costs, retaining wall construction costs, backfilling costs, etc. are added, which makes the construction labor and cost consuming and economical. It was not a good construction. Also, in the latter anchor construction method, there is a problem of reinforcing bar corrosion due to groundwater, so at present it is necessary to use it in combination with other construction methods (block stacking, leaning retaining wall, concrete frame construction) as described above. In the end, it caused an increase in construction cost.

The present invention has been made in view of the above circumstances, and provides a ground bolt reinforcing method capable of easily cutting steep slopes easily and at low cost while ensuring stability of strength of the ground. Is intended.

"Means for Solving the Problem" The earth bolt reinforcing method according to the present invention, in the ground to be cut, a plurality of ground bolts made of fiber reinforced plastic are previously inserted and fixed to reinforce the earth, Thereafter, the reinforced ground is excavated to cut the soil, and after the cutting is completed, the earth bolt exposed from the ground is cut.

[Operation] According to the present invention, the strength characteristics of the soil are improved by driving the earth bolts into the soil. In addition, the earth bolt resists the slip of the ground and prevents the protrusion of the cut slope after excavation by the pull-out resistance of the earth bolt. Furthermore, since the earth bolt is made of fiber reinforced plastic, there is no risk of corrosion due to groundwater or the like.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of a natural ground cut by the present invention. In this figure, a ground is represented by a symbol G, and its cross-sectional structure will be briefly described first. A cut slope 2 formed by cutting a slope 1 shown by a dotted line in the ground G
And the land for construction 3 at the lower end thereof is formed. A plurality of earth bolts 4 extending from the cut slope 2 toward the inside of the natural ground G are embedded in the natural ground G. These earth bolts 4 are arranged at equal intervals in the vertical direction and at equal intervals in the left and right. Further, a fiber grid 5 for protecting the cut slope 2 is laid on the surface of the cut slope 2, and a mortar 6 for protecting the cut slope 2 is sprayed on the fiber grid 5.

The earth bolt 4 is a fiber reinforced plastic (hereinafter simply referred to as FRP) as shown in FIGS. 3 and 4.
A rod-shaped cable (4a) and a spiral projection (4b) formed on the entire outer surface of the cable (4a).

In the cable 4a, a resin material 8 is wound around a core material 7 such as a paper pipe or a vinyl chloride pipe, and further, in the resin material 8,
A plurality of continuous fibers 9 ... Which extend in the longitudinal direction of the core material 7 are arranged so as to be embedded in the circumferential direction at intervals. As the continuous fibers 9, continuous fiber bundles made of long fibers such as lightweight and high-strength glass fibers and carbon fibers are preferably used, but if necessary, they may be combined with synthetic resin fibers, ceramic fibers, metal fibers or the like. You may use it. Similarly, as the resin material 8, a resin having good adhesiveness to the continuous fibers 9 and having sufficient strength characteristics by itself, such as vinyl ester resin, is preferably used. Further, other materials may be used depending on the material of the fiber 9 used. Examples of other resin materials include unsaturated polyester resins, epoxy resins, and phenol resins.

The protrusion 4b is for improving the adhesion property of the cable 4a to the natural ground G, and is composed of the continuous fiber 9.

The fiber grid 5 is made of the same material as the earth bolt 4 and has a structure in which continuous fibers such as high-strength glass fibers, carbon fibers, and aramid fibers are crossed in a mesh shape in multiple layers and impregnated with a resin. It is integrally molded.

Next, the procedure for creating the cut slope with the above configuration is
A description will be given with reference to FIGS.

(1) A predetermined number of perforations H are bored on the slope 1 of the ground G to be cut by a boring machine, a boring machine or the like, and the earth bolt 4 is inserted into each of the perforations H.

(Refer to Fig. 2 (a) and (b)) (2) Perforation H with a grout injection machine or a capsule
The solidifying agent 11 is spread throughout the inside, and (the cable 4a of) each ground bolt 4 is fixed in the hole H. As a result, the stability of the natural ground G is ensured, and at this time, the perforation H
Since the spiral protrusion 4b is formed on the surface of the cable 4a located at, the adhesion strength between the solidifying agent 10 and the cable 4a is sufficiently enhanced. (Refer to FIG. 4) (3) Excavation is started from the slope 1 of the ground G by an excavator or the like, and cutting is performed until the slope 2 reaches a predetermined slope (1: 0.6 to 1: 1.2). The discharged soil is transported to a predetermined place by a transportation means such as a truck and disposed of, or is used as a leveled soil on the land for construction 3.
(Refer to FIG. 2C) (4) After excavation and cutting of the ground G are completed, the surplus portions of the earth bolts 4 protruding from the cut slope 2 are cut.

(5) If the ground G is cohesive soil or the cut slope 3 is steep, the surface of the cut slope 3 may peel off, or the spray mortar 6 described below may peel off. When there is, the fiber grid 5 is laid over the entire surface of the slope. The fiber grid 5 is joined to the tip of the earth bolt 4. As a result, it is possible to prevent the cut slope 2 from protruding.

(6) Finally, the mortar 6 is sprayed over the entire cut slope 2 to a thickness of 10 to 15 cm to protect the cut slope 2 and, after laying the land 3 at the lower end thereof, etc. Work is done to complete the slope construction. (See FIG. 2D) The ground bolt 4 according to the present invention has a shape,
The dimensions and the like are not limited to those in the above embodiment, and various modifications are possible. For example, only the end of the earth bolt 4 has a protrusion 4b.
Alternatively, the tension force may be introduced by fixing it to the inner bottom of the perforation H and fixing the other end to the cut slope 2.

According to this embodiment, the following excellent effects can be obtained.

The strength characteristics of the natural ground G are improved by driving the ground bolt 4 in advance and reinforcing the natural ground G. Further, the earth bolt 4 resists the slip caused on the natural ground G due to an external force such as an earthquake. Further, the protrusion of the cut slope 2 after excavation can be suppressed by the pull-out resistance of the earth bolt 4.

By the action of the earth bolt 4 as shown above,
It is possible to increase the cut height for the natural ground G. Furthermore, even if the ground G is cohesive soil, steep excavation cutting is possible. That is, the slope of the cut slope 2 can be determined regardless of the soil condition of the natural ground G.

If slippage of the natural ground G is found during the cutting work, the ground bolt 4 can be immediately struck to reinforce the natural ground G.

Since the earth bolt 4 is made of FRP, it is easier to cut after excavating the ground than the conventional steel anchor. Also,
There is no concern about corrosion due to groundwater. Therefore, the earth bolt 4 can be permanently installed in the natural ground G, and the earth bolt 4 can be handled not as a temporary structure but as a permanent / permanent structure.

Since steep slope cutting is possible irrespective of the soil condition of the natural ground G, the flat land area can be made wider and the land can be effectively used, especially in a residential land development area.

When a steep slope is required in a place where the ground is not so good, such as cohesive soil, in the conventional publication, masonry after gentle slope cutting
The amount of excavated soil can be reduced because there is no need for a leaning retaining wall. Therefore, not only is the construction method extremely economically advantageous, but the construction period can be shortened and the construction can be simplified.

Since the cut slope 2 is protected by spraying the mortar 6, there is no fear of erosion due to rainwater or the like. Spraying mortar 6
If there is a risk of peeling, the fiber grid 5
If the mortar 6 is sprayed after being laid on the slope surface and fixed to the end of the earth bolt 4, the peeling can be prevented.

"Effects of the Invention" As described in detail above, according to the present invention, a plurality of earth bolts made of fiber-reinforced plastic are previously inserted and fixed in the ground to be cut to reinforce the ground. After that, after excavating the reinforced ground, cutting it, and cutting the earth bolt exposed from the ground after the cutting is completed, the cut height of the ground is increased. In addition to being able to take, it is possible to cut steep slopes even in the case of cohesive soil, and it is possible to determine the slope of the cut slope regardless of soil conditions. This enables not only economical construction but also shortening of construction period and simplification of construction.

Further, since the earth bolt is made of fiber reinforced plastic, it becomes possible to permanently install the earth bolt in the ground, which contributes to reduction of repair work for the cut slope.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a natural ground cut by the earth bolt reinforcing method according to the present invention, FIGS. 2 (a) to 2 (d) are explanatory views showing the procedure of cutting ground, and FIG. An enlarged view of the chain line IV in FIG. 1 and FIG. 4 are front sectional views of the earth bolt. 2 ... Cut slope, 4 ... Earth bolt, G ... Ground.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP 62-72817 (JP, A) JP 1-310017 (JP, A) JP 61-229024 (JP, A) JP 64-64- 29521 (JP, A)

Claims (1)

(57) [Claims] 1. A plurality of earth bolts made of fiber reinforced plastic are inserted and fixed in advance in the ground to be cut to reinforce the ground, and then the reinforced ground is excavated. The earth bolt reinforcing method is characterized in that the earth bolt exposed from the ground is cut after the soil is cut and cut.