JP2651863B2 - Composite anchor method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a composite anchor method incorporating the advantages of a rock bolt method and an anchor method.

<Conventional Technology> There has been known a rock bolt method in which a tensile material made of steel is inserted into an underground hole, and the entire length thereof is hardened with a mortar or the like.

On the other hand, there is also known an anchoring method in which only the back side of a tensile material inserted into a hole in the ground is hardened with mortar or the like, and a tensile force is applied from outside the hole to freely stretch the unhardened portion. .

<Problems to be Solved by the Present Invention> The rock bolt method is simple and economical because no tensile force is introduced, and is widely used under certain conditions.

 However, it also has the following disadvantages.

<B> It is not possible to positively prevent the displacement of the ground.

<B> Even when a rock bolt is driven, the boiling force acting on the previously installed rock bolt cannot be reduced.

<C> When reinforcing, it is necessary to drive a large number of lock bolts.

<D> Therefore, it was economical if the lock bolt could be used as it was, but once the structure was deformed, all the reinforcement work had to be performed again, which was uneconomical .

On the other hand, the anchor method has the following disadvantages.

<a> It is expensive because it involves many work steps and uses many types of materials.

<B> Once the tension is applied, it is difficult or impossible to change the load.

<C> Until you are nervous, the effect of the anchor cannot be exerted, and the anchor is unstable during that time.

<D> It is necessary to treat the exposed portion of the tensile member after tensioning.

<Object of the present invention> The present invention has been made in order to improve the above-mentioned conventional drawbacks, and has an object to provide the following composite anchor method.

<A> Anchor that can be constructed economically <B> Anchor that can be reinforced according to changes in conditions <C> Anchor that exhibits strength immediately after construction <Configuration of the present invention> Next, the present invention An embodiment will be described.

<A> Drilling (FIG. 1) The anchor hole 1 is excavated by a known method, and is drilled to a predetermined depth.

<B> Insertion of Outer Sheath (FIG. 2) The outer sheath 2 is inserted into the anchor hole 1.

The outer sheath 2 is a cylindrical body with a bottom 21 made of a synthetic resin or the like, and its surface is roughened or corrugated to obtain resistance.

An outflow hole 22 is formed in the bottom 21 or a part of the peripheral surface, and is used for injecting a curing agent such as mortar.

<C> Insertion of the inner sheath The inner sheath 3 is further inserted into the outer sheath 2.

The inner sheath 3 is also made of a synthetic resin or the like, is a cylindrical body with a bottom 31, and has a surface formed in the same manner as the outer sheath to obtain resistance.

 However, the bottom 31 is closed and no hole is provided.

<D> Insertion of temporary tensile material Before or after insertion of inner sheath 3, outer sheath 2
The primary tension member 4 is inserted between the inner sheath 3 and the inner sheath 3.

As the primary tensile member 4, a PC steel wire or a steel rod is used.

The outer end of the primary tension member 4 is exposed to the outside of the hole 1, but since no tension is applied, no special processing such as engraving a screw is required.

However, it is also possible to attach a simple structure to this part, and in that case, processing such as screws and plates is performed.

<E> Primary injection hole 1 between wall and outer sheath 2 and outer sheath 2
And a hardener 5 such as mortar is injected into a space between the inner sheath 3 and the inner sheath 3.

Since the hole 22 is opened in the bottom 21 of the outer sheath 2, this injection can be performed from any side of the outer sheath 2.

However, it is also possible to perform injection using another injection hose without opening the outflow hole 22.

<F> Completion of the primary anchor (FIG. 3) When the hardening agent 5 that has been primarily injected is hardened, the entire length of the primary tension member 4 is restrained by the hardening agent 5, and the construction of the primary anchor that functions as a lock bolt is completed.

However, in this case, a long hole 6 formed by the inner sheath 3 is formed in the center of the primary anchor.

<G> Insertion of secondary tension material Work is completed when the ground is stabilized by the primary anchor and its function is sufficiently performed.

However, when further reinforcement is required due to changes in the ground, the secondary tension member 7 is inserted into the long hole 6.

The secondary tension member 7 is also made of the same material as the primary tension member 4.

<H> Fixing of secondary tensile material The secondary curing agent 8 is injected only into the bottom of the long hole 6.

At this time, in order to prevent the secondary curing agent 8 from adhering to the entire length of the secondary tension member 7, asphalt,
The blocking unit 71 is provided with a urethane packer or the like.

When the secondary curing agent 8 is cured, fixing of only the tip portion of the secondary tension member 7 is completed.

In addition to such a method, in the free length portion of the secondary tension member 7,
It is also possible to use an unbonded material covered with a synthetic resin tube.

<T> Tension of secondary tension member The secondary tension member 7 is in a state where it is not restrained as a free length portion except for a fixing portion at the tip.

Therefore, if a tension is applied by grasping from the outside with a jack, the free length portion can be extended to introduce a prestress.

That is, the construction of the secondary anchor as the prestressed anchor is completed at this stage.

<Effects of the present invention> Since the present invention is constructed by the above method, the following effects can be expected.

<A> When the primary anchor functioning as a lock bolt alone is effective, the purpose can be sufficiently achieved by low-cost construction.

<B> When the ground is displaced, a secondary anchor can be used as a PC anchor by inserting a secondary tension material into the hollow long hole and hardening, and actively changing the ground Can be blocked.

<C> Therefore, it is economical when the primary anchor as the lock bolt can be used as it is, and once the structure is deformed, it is not necessary to perform all the reinforcement work again, and immediately the secondary anchor as the PC anchor You can switch to the next anchor and make it work.

<D> Generally, it takes some time until tension is introduced as a PC anchor.

However, in the method of the present invention, there is no unstable period during this time because the primary anchor functions as a lock bolt.

Therefore, it can be used for emergency construction such as measures against landslides during sliding.

[Brief description of the drawings]

 Fig. 1-4: Explanatory drawing of construction process of the present invention

Claims (1)

(57) [Claims] 1. A primary anchor is formed by inserting a primary tension member into a hole drilled in the ground and hardening the entire extension of the primary tension member with a mortar or the like, and a hollow is provided at the center of the primary anchor. In the hollow elongated hole, if necessary, insert a secondary tensile material into this hollow elongated hole. Of the entire extension of this secondary tensile material, only the inner part is hardened with mortar, and then Composite anchor construction method that composes secondary anchor by applying tension