JPH086327B2 - Anchor installation method for slope protection structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slope protection structure for preventing the slope from collapsing in order to prevent the slope from collapsing, and more particularly to a method of installing an anchor for fixing this structure to the ground. It is about.

[0002]

2. Description of the Related Art In order to prevent the slope from collapsing, a formwork is installed on the slope and a cement-based hardening material such as concrete or mortar is sprayed or cast in place to construct a structure. It is adopted to prevent the slope from rising. Anchor placed in the ground is passed through this structure, and this anchor is fixed to the structure with tension and prestressing force, and the structure is attracted to the ground and presses the ground. Is. When fixing the anchor to the slope protection structure, place a bearing plate with an anchor hole in the steel center on the structure cured by hardening a hardening material, pass the anchor through the anchor hole of the bearing plate, The anchor is fixed by a steel anchor head or nut further mounted on this.

[0003]

The problem in constructing such a structure is the curing period of the hardened material. The construction is a slope, and we want to fix the anchor as soon as possible to prevent the slope from collapsing, but if prestressing is applied to a structure that does not exhibit great strength in the young age, it will be hardened. Was sometimes broken or cracked. In particular, since a hole penetrates through the structure in order to pass the anchor, the lack of strength in this portion has become a very large neck. For this reason, a long curing period must be taken, and this curing period is a major cause of lengthening the construction period in the process.

Another problem in constructing this structure is that the bearing plate has a small area. Steel bearing plates are used on the structure, but the cost is high, and the large ones are not used. In addition, if it is made too large, there is a problem that it is heavy and difficult to handle, so that only a small bearing plate can be used. When a prestressing force is applied to the anchor, the force acts from the bearing plate with this small area, concentrating locally on the structure. When the hardened material does not exhibit sufficient strength, the pressure bearing plate often penetrates into the structure to cause large cracks in the structure.

Another problem with this structure is the problem of irregularities on the surface of the structure. The upper surface of the structure was generally finished by smoothing with a trowel without using a formwork. However, some unevenness is unavoidable on the surface, and when a flat pressure bearing plate is placed on this, only the convex portions of the structure come into contact with each other to form point contact. If a prestressing force is applied in this state, a bearing stress is locally generated in the structure, and the structure is often broken or cracked.

The present invention has been made to solve the above problems, and even when the curing period is short or the conventional bearing plate made of relatively small steel is used, the prestressing force is applied to the anchor. It is an object of the present invention to provide an anchor installation method in a slope protection structure that can give a crack and does not break the structure or generate a crack.

[0007]

An anchor installation method in a slope protection structure according to the present invention uses a precast plate manufactured in advance in a factory by using a cement-based hardening material. The precast plate is produced by hardening cement-based hardening materials such as mortar and concrete by arranging reinforcing bars inside. The precast plate is a plate material having a sufficiently large area as compared with the conventional steel pressure bearing plate, and has an anchor hole in the center thereof. The precast plate may have various shapes such as a square shape, a rectangular shape, a circular shape, and a polygonal shape. For example, a cross shape may be adopted depending on the shape of the structure on which the precast plate is placed.

It is preferable that the precast plate has high strength, and therefore, it is considered to use a hardening material in which ultrafine powder is kneaded. As the hardening material, 10 to 40 parts by weight of an ultrafine powder having an average particle size of 1 μm or less and 2 to 10 parts by weight of a high-performance water reducing agent are mixed with 100 parts by weight of cement, and a water cement ratio of 0.
It was kneaded with 3 or less. This may be cured in a paste state, or may be manufactured by mixing and kneading fine aggregate and then curing. Alternatively, both fine aggregate and coarse aggregate may be mixed and kneaded. Silicon or silica fume is suitable as the ultrafine powder, other fly ash,
Substances having low water solubility such as calcium carbonate, silica gel, titanium oxide and aluminum oxide can be used. Examples of the high-performance water reducing agent include those containing melamine dulonic acid formaldehyde condensate salt, naphthalene sulfonic acid formaldehyde condensate salt, polymeric lignin sulfonate, polycarboxylic acid, etc. as main components.

A formwork is installed on the slope. As the form, a form plate made of wood or a steel plate may be used, but a wire netting form plate of a crimped wire net or expanded metal may be used. Such a form plate is erected parallel to the left and right of the main bar arranged along the ground surface and held by a spacer or the like. The precast plate as described above is installed at the top end of this form, and the anchors placed in the ground are projected from the anchor holes formed in the center of the precast plate. The anchor may be a steel rod-shaped one such as a rock bolt, or a ground anchor type one in which a plurality of tensile materials such as steel strands are bundled and passed through a sheath. In this state, a cement-based hardening material such as concrete or mortar is sprayed or cast in place on the formwork.

A pressure bearing plate made of steel is installed on the precast plate, and an anchor is passed through an anchor hole opened at the center of the pressure bearing plate. An anchor head is further placed on the pressure support plate, and the anchor is tensioned in a state where the hardening material is hardened to a certain degree to give a prestressing force. A wedge secures the tension material of the anchor to the anchor head. If it is a lock bolt type anchor, fix it with a nut.

The precast plate may not be set in the formwork in advance, but may be placed later on the set curing material. In this case, it is preferable to apply vibration with a vibrator or the like to improve the adhesion between the precast plate and the curing material. It is the same work as above that a pressure bearing plate, an anchor head, etc. are placed on this and fixed.

It is possible to form holes or slits around the anchor holes in the precast plate and let water or air escape through the holes or slits to improve the adhesion between the precast plate and the hardening material.

[0013]

Operation: The precast plate is manufactured at the factory, and can be manufactured with strict formulation and specifications, and has the strength as designed. Moreover, the precast plate is larger than the pressure bearing plate, and the load can be widely dispersed. This makes it possible to apply a prestressing force even when the hardened material is a young material that does not exhibit the strength as in the past. The surface of the precast plate is formed to be smooth, and since the surface of the precast plate comes into surface contact with the bearing plate placed on the plate, the load is not concentrated on the local area.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. In the figure, 1 is a precast version,
In the examples, molding was performed using a cement-based hardening material mixed with ultrafine powder. Table 1 shows that for 100 parts by weight of cement claimed in the present invention, 1 part of ultrafine powder having an average particle size of 1 μm or less is used.
It is a table comparing 0 to 40 parts by weight, 2 to 10 parts by weight of a high performance water reducing agent and kneading with a water cement ratio of 0.3 or less, and other compounding comparative examples. In this implementation, a ferrosilicon byproduct having an average particle size of 0.5 μ is used as ultrafine powder.

[0015]

[Table 1]

In comparison with the comparative example, the example of the present invention has obtained an extremely large value in strength. This is because the ultrafine powder penetrates between the cement particles and the aggregate to form an extremely dense member. Also, the standard amount of high performance water reducing agent is 0.3 to 1.0 weight relative to cement,
In the present invention, more is added. A value of 10 parts by weight or less, preferably 2 to 5 parts by weight with respect to 100 parts by weight of cement is used to obtain a low water cement ratio for the kneaded product. If it is more than this, the water-reducing effect is not accompanied by an increase in the added amount, and rather adversely affects the curing.

Among the examples are calcium sulfate dihydrate,
Alternatively, some of the anhydrous salts are mixed with at least one kind. This gives greater strength. It is desirable to use hard materials as aggregates, and Mohs hardness is 6
The above is used. As the curing, general curing may be used, but it has been good to carry out accelerated curing such as steam curing.

The precast plate 1 produced in the factory as described above is carried into the site. A plurality of main bars 2 are arranged in parallel on the slope, and a left and right form frame plate 3 made of a crimp wire mesh.
・ Install 3. The formwork plates 3 and 3 are either connected to the stirrup streaks arranged around the main bar 2 or are stood upright with a spacer therebetween. Anchors 5 are preliminarily placed on the natural ground, and the anchors 5 project to the ground surface between the mold plates 3 and 3. As the anchor 5, a ground anchor in which a plurality of tension members 7 are bundled and passed through a sheath 6 is used. The precast plate 1 shown in FIG. 1 is rectangular and has an anchor hole 4 in the center. This anchor hole 4
The precast plate 1 is attached to the top end position of the formwork plates 3 and 3 through the anchor 5 protruding from the ground surface. The precast version can be attached by placing a spacer on the stirrup streak and installing it on it. Under the precast plate 1, a protective sheath 9 having packing 8 attached to the inner periphery of the anchor 5 is arranged. The protective sheath 9 may be integrally attached to the back surface of the precast plate 1 in advance.

Concrete 10, which is a cement-based hardening material, is sprayed onto the above mold. The concrete 10 is well spread under the precast plate. Concrete 1
After the 0 has hardened to a certain extent, the tensile member 7 is precast
Through the anchor holes 12 of the steel bearing plate 11 placed on the above, and further each hole 14 of the anchor head 13 placed thereon
Pass through. In this state, the tension member 7 is tensioned to give a prestressing force, and is fixed by the wedge 15. Concrete 1
Even when the curing of 0 is performed for about 3 days, the prestressing force is dispersed by the precast plate 1 and acts on the structure 16, so that the structure 16 is not broken or cracked.

When the precast plate 1 is placed on the structure 16 after the setting of the curing material, vibration is applied by the vibrator to improve the adhesion between the curing material and the precast plate 1. The tension and fixation of the anchor 5 may be performed by the same procedure as above.

FIG. 2 shows a square precast plate 1
FIG. 3 shows a case where the square precast plate 1 is placed so as to fill the width of the structure 16 as well. 4 and 5 show the case where the rectangular precast plate 1 is also used, and by doing so, the area of the precast plate 1 can be further increased. Figure 6 shows the structure 1 crossing the slope vertically and horizontally.
This is a case where the crossing portion is fixed to the anchor 5 when 6 is constructed. The precast plate 1 is also formed in a cross shape so that the load is dispersed over a wider area. FIG. 7 shows the intersection of the structure 16 as well, but a reinforcing portion 17 is formed on the structure 16 so as to surround the intersection, and the polygonal shape is formed so that the load is also dispersed in the reinforcing portion 17. I am using precast version 1 of. As shown in FIG. 8, a plurality of dowels 18 are projected on the back surface of the precast plate 1 to enhance the integration with the hardening material. There is also an idea to provide unevenness on the back surface instead of this gibber. Further, FIG. 9 shows a case where a plurality of slits 19 are formed in the precast plate 16, and water or air in the hardened material is allowed to escape from the slits 19 to improve the adhesion between the precast plate 1 and the hardened material. ing. FIG. 11 shows the case where the central portion is thickest and the thickness is gradually reduced from the central portion to the end portion. In other words, it is the pressure bearing plate 11 that should be flat.
Only the part to put on is required, and other shapes can be designed variously depending on the situation. In FIG. 11, the reinforcing portion 1 surrounding the intersecting portion
7 is also provided.

[0022]

Since the present invention has the above-mentioned structure, the following effects can be obtained. The precast plate, which has been manufactured in the factory in advance and has the strength as designed, is placed on the hardened material, so even if the hardened material is in a young age before the material develops sufficient strength, the strength is compensated for. At the same time, the load can be dispersed over a wide area. Therefore, the curing period of the hardened material can be shortened to accelerate the process and shorten the construction period. Since the load when prestressing force is applied by the precast plate is widely dispersed, the load is not locally concentrated and the structure is not broken or cracked. Since the precast plate is produced at the factory, the surface can be made smooth, and the surface contact with the pressure bearing plate prevents the load from being locally concentrated. By manufacturing a precast plate with a hardening material mixed with ultrafine powder and a high-performance water reducing agent, a precast plate having a greater strength is obtained, and there is no fear of damage even if a greater prestressing force is applied. By mixing the ultrafine powder, it is less likely that bubbles will form in the precast plate, and rainwater will not penetrate. By covering the circumference of the anchor with this precast plate, penetration of rainwater can be reduced even if a small crack is formed in the hardened material. By forming holes or slits in the precast plate, it is possible to allow water and air in the curing material to escape, and to improve the adhesion between the precast plate and the curing material.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of an anchor installation method in a slope protection structure according to the present invention.

FIG. 2 is a plan view of an embodiment in which a precast plate is installed on a structure.

FIG. 3 is a plan view of an embodiment in which a precast plate is installed on a structure.

FIG. 4 is a plan view of an embodiment in which a precast plate is installed on a structure.

FIG. 5 is a plan view of an example in which a precast plate is installed on a structure.

FIG. 6 is a plan view of an embodiment in which a precast plate is installed on a structure.

FIG. 7 is a plan view of an embodiment in which a precast plate is installed on a structure.

FIG. 8 is a cross-sectional view of an embodiment in which a precast plate is installed on a structure.

FIG. 9 is a plan view of another embodiment of the precast plate.

FIG. 10 is an overall view of a slope protection structure.

FIG. 11 is a perspective view of another embodiment in which a precast plate is installed on a structure.

[Explanation of symbols]

 1 Precast Plate 2 Main Bar 3 Formwork Plate 4 Anchor Hole 5 Anchor 6 Sheath 7 Tensile Material 8 Packing 9 Protective Sheath 10 Concrete 11 Pressure Bearing Plate 12 Anchor Hole 13 Anchor Head 14 Hole 15 Wedge 16 Structure 17 Reinforcement Part 18 Gibel 19 Slit

Claims (5)

[Claims] 1. A relatively large area precast plate having an anchor hole formed in the central portion is arranged at a top end position of a formwork installed on a slope, and a cement-based hardening material is sprayed onto the formwork or Place it in place and harden it to a certain extent, place a steel bearing plate with an anchor hole at the center on the precast plate, and place it on the ground to anchor holes in the precast plate and bearing plate. Anchor installation method in slope protection structure where tension is applied to the anchor passed through to give prestressing force, and it is fixed to the anchor head plate or nut further placed on the bearing plate. 2. The cement is prepared by spraying or place-casting a cement-based hardening material on a formwork installed on the slope, and installing a precast plate having a comparatively large area with an anchor hole in the center on it. After curing the system hardening material to some extent, the precast plate and the anchor placed on the ground in both anchor holes of the steel bearing plate, which also has an anchor hole in the center, placed on this plate. An anchor installation method in a slope protection structure in which this anchor is tensioned to give a pre-stressing force and is fixed to the anchor head or nut further mounted on the bearing plate. 3. The method for installing an anchor in a slope protection structure according to claim 2, wherein after the precast plate is installed, vibration is applied to improve the adhesion between the precast plate and the cement-based hardening material. 4. The precast plate contains 10 to 40 parts by weight of ultrafine powder having an average particle size of 1 μm or less and 2 to 10 parts by weight of a high-performance water reducing agent to 100 parts by weight of cement, and a water-cement ratio of 0. The anchor installation method in the slope protection structure according to claim 1, wherein the anchor is installed by using a hardened material that is kneaded at a ratio of 3 or less. 5. The method for installing an anchor for a slope protection structure according to claim 1, 2, 3 or 4, wherein the precast plate has a plurality of holes or slits formed around the anchor hole.