JPH0696858B2 - Ground anchor construction method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground anchor which is buried in the ground and fixed to bear a force acting on a connected structure.

[0002]

2. Description of the Related Art In some cases, embankment is formed on a slope or a valley slope of a road to form a flat site or a new road portion protruding from the natural ground. As a means for supporting such an embankment portion so as not to collapse, a method as shown in FIG. 3 is adopted. That is, a part of the ground anchor G in which a plurality of tension members c are arranged inside the sheath d is inserted and fixed in the excavation hole b excavated in the existing natural ground a, and the remaining part is fixed. Is embedded in the embankment e and connected to a structure f such as a panel arranged on the valley side of the embankment e. The load acting on the embankment e acts as a force to separate the structure f on the valley side from the ground, and this force is supported by the ground anchor G.

[0003]

A problem in this construction is that the embankment e sinks due to aging. That is, as the time after construction elapses, the embankment e sinks due to reasons such as compaction, and the ground anchor G partially filled in the embankment e is also pushed down accordingly. Since there is no change such as subsidence in the existing ground a and the e portion of the embankment is relatively lowered, the ground anchor G in the existing ground a
Therefore, only a part in the embankment e is lowered with respect to a part of. As a result, a large stress acts on a portion near the boundary between the embankment e of the anchor G and the existing ground a.

This stress acts to bend the portion near the boundary of the anchor G. When the anchor G bends,
The sheath d comes into contact with the tension member c inside, and the friction generated between the two becomes extremely large.
In the free length portion of the anchor G, it is necessary to guarantee the free elongation of the tension member c. Thus, the friction between the sheath d and the tension member c causes the tension member c as designed.
Will not be obtained. Further, when a larger local stress is applied, the sheath d at the boundary portion of the anchor G may be split, and water may infiltrate from this portion to cause the tensile member c to rust, resulting in the tensile member. There was a case where c was broken.

When the embankment e sinks, the embankment e may be cut by the sheath d of the thin anchor G, and a void may be formed immediately below the sheath d. The anchor G sags in this space, and when a load is applied to the structure f, the sag extends,
The structure f may be displaced.

The present invention has been made in order to solve the above problems, and it is possible to guarantee the extension of the free length portion of the anchor even when a local stress acts, and to prevent the damage of the sheath. It is also an object of the present invention to provide a ground anchor construction method that does not cause slack in the anchor.

[0007]

The construction method of the ground anchor according to the present invention is to reinforce this part by making a part of the anchor on which the local stress acts multiple.
It is a part of the sheath near the boundary between the ground and the embankment that is to be duplicated. The vicinity of the boundary means a desired length extending over both the embankment portion and the ground portion. As a means to multiplex
It is conceivable to cover the sheath with a tubular body. It is also conceivable to arrange the tube inside the sheath. Although various members can be adopted as this tubular body, for example, a sheath can be further arranged around the sheath to be multiplexed, and as the sheath, a synthetic resin sheath such as polyethylene, or a stainless steel spiral sheath having irregularities on the circumferential surface. Well-known members such as a winding sheath can be widely adopted. Further, not only the sheath but also steel pipes, concrete pipes and the like can be similarly adopted. These pipes are reinforced by making them double, triple, etc.

[0008]

[Operation] The embankment sinks and local stress acts near the boundary of the anchor. Against this stress, the bending of the anchor is prevented by the sheath reinforced in multiple layers. Also, the sheath is prevented from being split by stress. When multiple pipes are arranged around the periphery, the diameter of the sheath becomes thicker by that amount, so that the embankment is not cut and a void is not formed immediately below the sheath.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on an embodiment shown in the drawings. In the figure, 1 is the ground of the slope,
A part of the ground anchor 3 is inserted into the excavation hole 2 excavated in the natural ground 1. The ground anchor 3 has a tensile member made of a plurality of steel strands arranged in a sheath 4, and the bottom side of the excavation hole 2 of the sheath 4 serves as a fixing portion sheath such as a spiral sheath. This drill hole 2
The anchor 3 is fixed by injecting a hardening material 5 such as mortar.

[0010] A part of the sheath 4 of the anchor 3 is covered with a tubular body 6 over the desired length of a portion of the ground 1 slightly entering the excavation hole 2 and a portion of the ground 1 protruding from the ground 1. . A steel pipe is used as the pipe body 6. The tubular body 6 doubles and reinforces the portion near the boundary of the sheath 4. An earth retaining panel 8 stacked on the foundation portion 7 is connected to the tip of the anchor 3. For the connection, a tension member may be fixed with a nut or the like. The panel 8 is made of a material having a high rigidity with the middle part bent in an arc shape.
The embankment 9 is filled between the panel 8 and the ground 6.

In the above-mentioned construction, the embankment 9 sinks and falls relatively to the ground 1, and the embankment 9 of the anchor 3
Even if a local stress is applied to the vicinity of the boundary between the ground and the ground 1, the reinforced sheath 4 does not easily bend, and friction does not occur between the sheath 4 and the tensile member inside. Therefore, the free elongation of the tensile member is not hindered. Further, the sheath 4 will not be split. Further, the embankment 9 is not cut off by the sheath 4 having a larger diameter by arranging the tubular body 6 in the periphery, and no void is formed immediately below the sheath 4.

The present invention is not limited to the above embodiment,
The pipe 6 may be continuously covered over the desired length of the excavation hole 2 of the natural ground 1 and the entire length from the ground surface to the structure. This can reduce the influence of the stress acting on the entire length of the protruding portion of the anchor 3 from the natural ground.
Further, the structure is not limited to the panel 8, but can be applied to construction of a slope protection block, a structure cast on site, or the like.

[0013]

The present invention has the above-mentioned structure and can obtain the following effects. Since the embankment of the sheath, where local stress acts due to the settlement of the embankment, and the area near the natural ground were multiplexed and reinforced, there was no bending of the sheath due to this stress that hinders the free extension of the tensile member. Does not impair function. The local stress does not cause the sheath to split, and the penetration of water to rust the tensile material into the sheath does not occur. By covering the sheath with a tubular body, the diameter of the sheath is substantially increased, the embankment is not cut by the sheath, a void is not formed immediately below the sheath, and the slack of the anchor does not occur. The thickened diameter receives the subsidence stress of the embankment and supports it, so that the bearing stress to the ground is dispersed and the ground collapse and subsidence do not occur.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a method of constructing a ground anchor according to the present invention.

FIG. 2 is a sectional view of a construction state.

FIG. 3 is a partial cross-sectional view of a conventional construction state.

[Explanation of symbols]

 1 Ground 2 Drilling hole 3 Ground anchor 4 Sheath 5 Hardened material 6 Tubular body 7 Foundation 8 Earth retaining panel 9 Embankment

Claims (2)

[Claims] 1. A part of a ground anchor, in which a tensile material is arranged in a sheath, is inserted into a hole excavated in the ground and fixed therein, and a part of the ground side protrudes from the hole in the ground. A method of constructing a ground anchor, characterized in that, when the ground anchor is buried in the embankment, a portion near the boundary between the ground and the embankment, which is a part of the sheath, is reinforced in multiple layers. 2. The method for constructing a ground anchor according to claim 1, wherein the outer circumference of a portion near the boundary between the ground and the embankment of the sheath is covered with a tube to make it multiple.