JPH05195529A - Construction of corrosion-resistant double anchor - Google Patents

Abstract

PURPOSE:To quickly and simply construct a corrosion-resistant double anchor. CONSTITUTION:The ground where anchor is to be set is excavated to form an anchor hole (h) at a given deep position, and a corrosion-resistant double sheath 12 is inserted into the center of the hole (h) over the whole length of the hole (h). A grout 13 is packed to the space between the sheath 12 and the pit wall, and a tension steel part 1 covered with a polyethylene sheath 3 over its free length portion is inserted into the sheath 12. A grout 14 is then packed into the space between the steel part 1 and the sheath 12. After the grouts 13 and 14 are hardened, a tension is introduced into the steel part 1 to set an anchor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a ground anchor installed in the ground for the purpose of preventing landslides, and particularly to a construction method of a double anticorrosion anchor having excellent long-term durability.

[0002]

2. Description of the Related Art Various improvements have been added to the anchor construction method that started from a temporary construction method in recent years, and in recent years, as a permanent anchor, the structure can be overturned / stable, landslide prevention, uplifting prevention, stability when excavating underground caverns, etc. It has come to be used for many purposes. Since the function of the permanent anchor has to be stably maintained for a long period of time while the structure is present, much consideration is given to rust prevention as compared with the temporary anchor. For example, according to the Japan Society of Geotechnical Standards “Grand Anchor Design / Construction Standards”, in the case of permanent anchors, especially long-term stability of the anchored ground, safety against corrosion, and methods for maintenance after use [3. 3 (2)]. In principle, permanent anchors are based on double corrosion protection [5.1 (2)]. As a general rule, the tendon in the permanent anchor is placed in a capsule and the inside is filled with grout or the like [5.2 (1)]. The temporary anchors have different corrosion protection grades.

At present, there are various anchor construction methods such as the VSL permanent anchor construction method, the STK permanent anchor construction method, the PTC permanent anchor construction method, and the SHS permanent anchor construction method which are used as permanent anchors satisfying the above-mentioned criteria.

On the other hand, in the existing single anticorrosion anchor construction method and the like, various improvements have been made so that the original characteristics of the construction method can be utilized while the double anticorrosion is applied by improvement to withstand the use as a permanent anchor. .. For example,
In Japanese Unexamined Patent Publication No. 61-42046, as shown in FIG. 8, a manchette tube 20 is inserted along a tendon 21 contained in a capsule, and the tendon 2
The anchor body formed around 1 is disclosed as a method of performing pressure grout injection from the manchette tube 20. According to this construction method, the anchor body can be formed while improving the surrounding ground due to the advantage of the Soletanche construction method, so that it can be applied to a wide range of ground from soft ground to rock with many cracks.

[0005]

However, in the case of the above-mentioned various permanent anchors, the working and assembling work of the tendon is complicated, and the waterproof treatment at the boundary between the free length portion and the fixing length portion and the tip portion Since the water-stopping treatment requires a lot of time and labor such as filling with a hot-melt adhesive or the like, it is desired that the construction be quick and simplified. Further, in the case of the permanent anchor according to the above-mentioned Japanese Patent Laid-Open No. 61-42046, it is necessary to make a large hole diameter so that both the tendon 21 and the manchette tube 20 can be inserted at the same time. The cost increases and it becomes uneconomical. In addition, the grout material injected from the manchette tube 20 should spread radially and surround the manchette tube 20 evenly.
In some cases, the injection of the portion due to the injection is blocked, and an uninjected portion may be formed.

Further, the above-mentioned VSL permanent anchor construction is a grout pressureless anchor which is performed by injecting grout material from the tip of the tendon material, and although there is no problem mainly in fixed ground where the grout material does not dissipate, When applying to the ground where loosening of the fixing ground at the time of drilling may cause a decrease in pull-out resistance, for example when expanding the applicable ground type, the ground and anchor body should be in close contact. Therefore, it is necessary to use a grout pressure anchor using a packer. However, this method is also not practical because it has a problem that the hole diameter needs to be increased.

Therefore, the main object of the present invention is to construct a pressure-injection type anchor that can be applied to a wide range of grounds, while achieving double corrosion protection, speeding up and simplifying construction, and also having a small hole diameter and good work efficiency. An anchor construction method for doing so is provided.

[0008]

[Means for Solving the Problems] The above-mentioned problem is that, after the anchor installation target ground is drilled to a predetermined deep depth to form an anchor tensile steel material installation hole, first, the anchor is installed substantially at the central axis position of the installation hole. A double anticorrosion sheath or steel pipe having a diameter larger than that of the tensile steel is inserted over the entire length of the installation hole, and a grout material is filled between the double anticorrosion sheath or steel pipe and the hole wall. Inside the edible sheath or steel pipe, at least the steel material of the free length portion on the anchor base end side is covered with a coating material, and the tensile steel material in which slippage is ensured at that portion is inserted. The problem can be solved by filling a grout material between the double anticorrosion sheath or the inner wall of the steel pipe, waiting for the filled grout material to harden, and introducing a tension force to the tensile steel material. At this time, it is also possible to use a corrugated unevenness formed on a part or the whole of the wall surface of the double anticorrosion sheath.

When pressure injection is performed, the anchor installation target ground is drilled to a predetermined deep depth to form an anchor tensile steel material installation hole, and first, at a substantially central axis position of this installation hole. Injection holes are formed at a predetermined interval in the longitudinal direction in a range that has a diameter larger than that of the tensile steel material and that corresponds to at least the anchoring long portion on the anchor tip side over substantially the entire length of the installation hole. A manchette tube or a sleeve pipe provided with a rubber sleeve valve for wrapping is built in, and a double packer that straddles the rubber sleeve part is provided inside, and a grout injection hole is formed in the middle part of the double packer. After inserting the pipe and sequentially injecting grout from each rubber sleeve part to the outside, pull out the injection pipe and remove it, The pipe or sleeve pipe is left in the ground, and inside the manchette tube or sleeve pipe, at least the steel material at the proximal free side is covered with a coating material, and tension is secured to ensure slippage at that portion. Inserting a steel material, then filling the grout material between the tensile steel material and the inner wall of the manchette tube or sleeve pipe, waiting for hardening of the injected and filled grout material, and introducing tension to the tensile steel material. Can be solved with. At this time, preferably, the ground injection is performed a plurality of times through the Manchette tube or the sleeve pipe by the injection pipe. It is also possible to use one in which corrugated irregularities are formed on a part or all of the wall surface of the manchette tube or sleeve pipe.

[0010]

In the present invention, after the anchor installation hole is formed in the ground on which the anchor is installed, first, in order to secure the adhesive strength evenly with the grout material filled in the surroundings, the substantially central axis position of the installation hole is set. In order to surround the entire tensile steel material, a double anticorrosion sheath or steel pipe having a diameter larger than that of the tensile steel material is inserted over substantially the entire length of the installation hole. Then, a grout material is filled between the double anticorrosion sheath or steel pipe and the hole wall, and at least the free length portion on the anchor base end side is covered with a coating material inside the double anticorrosion sheath or steel pipe. Then, a tensile steel material in which slippage is ensured in the portion is inserted, and then a grout material is filled between the inserted tensile steel material and the inner wall of the double anticorrosion sheath or steel pipe. Then, after waiting for the hardening of these filled grout materials, tension is introduced into the tensile steel material. As described above, first, the sheath or the steel pipe to be the double anticorrosion capsule and the tensile steel material are separately inserted into the anchor installation holes, so that the working and assembling work of the uncurtain dong can be substantially eliminated. At the same time, it is not necessary to perform the water stoppage treatment at the boundary between the free length portion and the fixed length portion, and the water stoppage treatment at the tip portion.
At this time, if a corrugated unevenness is formed on a part or all of the double anticorrosion sheath wall surface, pullout resistance can be secured and tension can be increased.

When pressure injection is performed, an anchor tensile steel material installation hole is first formed, and then a manchette tube or a sleeve pipe is first installed in this installation hole, and the injection pipe is inserted thereinto, Grouting is sequentially carried out from each of the rubber sleeves to improve the surrounding ground. At this time, it is possible to ensure ground improvement by performing ground injection multiple times at the place where the grout material escapes, or for the entire range, and at the same time, loose sand ground,
Even the soft ground can be improved to the extent that a considerable anchor tension can be introduced. Thereafter, the injection pipe was pulled out and withdrawn, and the manchette tube or sleeve pipe was left in the ground, and inside the manchette tube or sleeve pipe, at least the proximal free side portion was covered with a covering material, and A tensile steel material, which is ensured to slip on the part, is inserted, and a grout material is filled between the tensile steel material and the inner wall of the manchette tube or the sleeve pipe. In this way, the manchette tube or sleeve pipe used for ground injection can be used as it is as a double rust preventive capsule to reduce the drilling diameter, and at the same time, the complicated uncurtain donation method used in conventional permanent anchor construction methods. It is possible to substantially eliminate the processing and assembling work and the water stop treatment of.

[0012]

EXAMPLES The present invention will be described in detail below based on examples. FIG. 1 is a structural diagram of a double anticorrosion anchor according to the present invention,
FIG. 4 is a transverse cross-sectional view of the main parts of FIGS. 2 and 3. The double anticorrosion capsule 2 is inserted and installed over substantially the entire length of the anchor installation hole h formed in the ground, and the tensile steel material 1 is inserted into the double anticorrosion capsule 2.
In the space between the double anticorrosion capsule 2 and the anchor installation hole h, the grout material 9 is pressurized and injected by the ground injection, and the surrounding ground and the anchor fixing portion A are integrally and firmly fixed. The space between the tensile steel material 1 and the double anticorrosion capsule 2 is filled with an internal grout material 10. Therefore, the tension force introduced into the tensile steel material 1 is generated by the internal grout material 10 and the double anticorrosion capsule 2.
And it is transmitted to the surrounding ground through the grout material 9.

In the double anticorrosion capsule 2, the fixed length portion A on the tip side of the anchor is constituted by a steel pipe manchette shoe 2A, and the free length portion B on the anchor base side is constituted by a vinyl chloride pipe (VP65) 2B. Was
It is connected and joined near the boundary. In addition, the steel pipe manchette shoe 2A and the vinyl chloride pipe 2B
The boundary between and may deviate from the boundary toward the free length portion by about several meters. As shown in detail in FIG. 4, the steel pipe manchette shoe 2A has injection holes 2a, 2a ... Formed at appropriate intervals (several tens of cm) in the axial direction of the members and the injection holes 2a, 2a. Rubber sleeve 6 for covering
Are attached so as to enclose the tube 2A. This steel pipe manchette tube 2A functions as a double rust-preventing capsule of the tensile steel material 1 inserted inside after finishing the ground injection for forming the anchor body, but in the ground injection, it is shown in FIG. As described above, there are packers 5a, 5b having a diameter large enough to slide on the inner wall of the steel pipe manchette tube 2A at a predetermined distance, and the injection holes 5c, 5c ... Are formed on the pipe wall surface between the packers 5a, 5b. The formed injection pipe 5 is connected to the steel pipe Manchette tube 2
By inserting the grout material 9 with a predetermined pressure from the injection holes 5c, 5c ... Of the injection pipe 5 with the rubber sleeve 6 of A being inserted so as to straddle the packers 5a, 5b. Thus, the outflow of grout in the pipe axis direction is regulated, and the grout material 9 spreads the rubber sleeve 6 and is radially injected into the surrounding ground. The injection pipe 5 has a fixing length by feeding a grout of a controlled injection amount and injection pressure at the position where the rubber sleeves 6 of the steel pipe manchette tube 2A are arranged according to the conditions of each layer in the depth direction of the ground. It is possible to form a strong anchor body over the entire part A. In addition, one of the features of this method is the advantage that injection can be repeated many times. For example, when an anchor body is formed on soft ground, loose sand ground, etc., this repetitive injection can greatly increase the pulling force. In addition, in this embodiment,
Although the steel material is used for the manchette tube, the material is not limited to the steel material, and may be a resin material such as high-density polyethylene. Also, a sleeve pipe used in the sleeve construction method can be used. Further, in order to increase the pullout resistance with the grout material, it is also possible to use one having corrugated irregularities on the wall portion. In this case, preferably, the arrangement position of the rubber sleeve 6 or the packer 5a, 5b position of the injection pipe 5 is preferably smooth. Therefore, as shown in FIG. It is desirable to use a specially formed Manchette tube 2A. A center riser 4 is attached at an appropriate position in the longitudinal direction of the manchette tube 2A, and is arranged in the central portion of the anchor installation hole h in an inserted state.

Since the vinyl chloride pipe 2B arranged in the free length portion B of the anchor does not require soil injection, a blind pipe having no injection hole is used, but the material is not limited to this. Instead, it may be another resin material such as high-density polyethylene or a steel material to which the steel pipe manchette tube 2A extends.

On the other hand, the tensile steel material 1 of 7 twisted PC steel twisted wire 24.3φmm inserted in the double rustproof capsule 2 is a steel material which is bare at the anchoring long portion A portion on the anchor tip side. Is exposed, and the free length portion B on the base end side is coated with the rust preventive oil and then the polyethylene sheath 3
By the so-called unbonding process, which is covered by
After being cut off from the surroundings and inserted into the steel pipe manchette tube 2A, the grout 10 material is filled into the steel pipe manchette tube 2A by the injection pipe 7 shown by the broken line in FIG. A tension force is introduced to the tensile steel material 1 after the filled grout material 10 is hardened, but the steel material in the free length portion B has a slip during tension due to the unbonding process. The tensile steel material 1 is not limited to the PC steel twisted wire but may be a PC steel rod. Further, the coating material is not limited to the unbonding process, and may be a method in which a durable tape-shaped coating material infiltrated with rust prevention is wound around the steel material.

When the tensile steel material 1 is inserted, spacers 8 are provided at appropriate positions so as to be arranged at the central axis position of the manchette tube 2A. Also,
The head of the tensile steel material 1 is attached with the condominium 1C which is formed by wrapping the steel material 1 and crimping it, and when introducing the tension force, it is fixed by screwing a nut.

The structure of the double rust preventive anchor according to the present invention has been described in detail above. Next, the construction method will be described in detail with reference to FIG. Note that FIG. 6 shows a part of the anchored long portion A of the anchor. First, as shown in FIG. 6A, the anchor installation target ground is drilled up to a predetermined ground depth by using the casing 15 as necessary to form an anchor tensile steel material installation hole h. next,
As shown in FIG. 6B, the Manchette tube 2
Is inserted in the center of the installation hole h (the vinyl chloride pipe 2B of the free length is also inserted at the same time), the sleeve grout 11 is filled between the manchette tube 2A and the installation hole wall, and the casing 15 is pulled out. continue,
As shown in FIG. 6C, the manchette tube 2
The injection pipe 5 is inserted into the inside of A, and grout injection is sequentially performed from the position where each rubber sleeve 6 is disposed to the surrounding ground to form an anchor body. When injecting into the ground, if necessary, repeat injections will be carried out multiple times at key points.
The second and subsequent injections are managed by controlling the grout pressure.
It is determined whether sufficient injection has been made. When the grout injection is completed for the outer peripheral portion of the manchette tube 2A, the injection pipe 5 is pulled out and removed, and the manchette tube 2A is left in the ground as it is, and the tensile steel material 1 is inserted thereinto, and the manchette is also inserted. The tube 2A is filled with grout material. Then, after the grout materials are hardened, tension is introduced into the tensile steel material 1 and the anchors are installed.

Next, the construction of the double rust preventive anchor by pressureless grout injection will be described in detail with reference to FIG. First,
As shown in FIG. 7A, with respect to the ground on which the anchor is to be installed, the casing 15 may be formed up to a predetermined ground depth if necessary.
The hole is drilled while using, and the installation hole h of the anchor tensile steel material is formed. Next, as shown in FIG. 7 (b), a double anticorrosion sheath (or steel pipe) 12 to be a double rustproof capsule.
Is inserted in the center of the installation hole h, and the grout material 13 is provided between the double anticorrosion sheath (or steel pipe) 12 and the installation hole wall.
And the casing 15 is pulled out. Subsequently, as shown in FIG. 7 (c), at least the free length portion on the anchor base end side is covered with the polyethylene sheath 3, and the tensile steel material 1 in which sliding at the portion is secured is inserted. A grout material 14 is filled between the tensile steel material 1 and the inner wall of the double anticorrosion sheath (or steel tube) 12. Then, these filled grout materials 13, 14
After waiting for the hardening, the tensile force is introduced into the tensile steel material 1 to install the anchor.

[0019]

As described above in detail, according to the present invention, it is possible to install a double anticorrosion anchor that can be used as a permanent anchor while achieving quick and simple construction. In addition, even for soft ground, loose sand ground, etc., a strong anchor body can be created by pressure injection to expand the applicable ground types, and the drilling diameter is small and work is efficient. A heavy anticorrosion anchor can be installed.

[Brief description of drawings]

FIG. 1 is a structural diagram of a double anticorrosion anchor according to the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

3 is a cross-sectional view taken along the line III-III in FIG.

FIG. 4 is an enlarged vertical sectional view of a main part of a Manchette tube.

FIG. 5 is a modification view of the Manchette tube.

FIG. 6 is a process diagram of an installation procedure of a grout pressurizing double anticorrosion anchor according to the present invention.

FIG. 7 is a process diagram of an installation procedure of a grout pressureless double anticorrosion anchor according to the present invention.

FIG. 8 is a structural diagram of a conventional permanent anchor.

[Explanation of symbols]

1 ... Tensile steel material, 2/12 ... Double anticorrosion capsule, 2A ...
Steel pipe Manchette tube, 2B ... Vinyl chloride pipe, 3 ... Polyethylene sheath, 4 ... Center riser,
5 ... injection pipe, 6 ... rubber sleeve, 7 ... injection pipe, 8 ...
Spacer, 9/10/13/14 ... Grout material, h ... Anchor installation hole

Claims (5)

[Claims] 1. An anchor installation ground is drilled to a predetermined deep area to form an anchor tensile steel material installation hole,
First, insert a double anticorrosion sheath or steel pipe having a diameter larger than that of the tensile steel material approximately at the central axis position of the installation hole over the entire length of the installation hole, and insert between the double anticorrosion sheath or steel pipe and the hole wall. In addition to filling the grout material in, the inside of the double anticorrosion sheath or steel pipe, at least the steel material of the free length portion on the anchor base end side is covered with a coating material, and a tensile steel material in which slippage is secured in the portion is secured. Inserted, then filled with grout material between the inserted tensile steel material and the inner wall of the double anticorrosion sheath or steel pipe, wait for hardening of the filled grout material, and apply tension to the tensile steel material. A method of constructing a double anticorrosion anchor characterized by being introduced. 2. A corrugated unevenness is formed on a part or all of the wall surface of the double anticorrosion sheath.
Construction method of double anticorrosion anchor. 3. Anchor installation target ground is drilled to a predetermined deep part of the ground to form an anchor tensile steel material installation hole,
First, at a substantially central axis position of this installation hole, over a substantially entire length of the installation hole, to a range having a diameter larger than that of the tensile steel material and at least corresponding to a fixing length portion on the tip side of the anchor, a predetermined length direction is set. An injection hole is formed at intervals, and a manchette tube or a sleeve pipe provided with a rubber sleeve valve that wraps the injection hole is built, and a double packer that straddles the rubber sleeve portion is provided inside the manchette tube or the sleeve pipe.
After inserting the injection pipe with the grout injection hole formed in the middle part of the double packer and sequentially performing the grout injection from the rubber sleeve portions to the outside, the injection pipe is pulled out and removed, and the manchette tube or the sleeve is used. About the pipe, leave it in the ground, inside this Manchette tube or sleeve pipe,
At least the steel part of the proximal free side is covered with a covering material, and the tensile steel material in which slippage is ensured is inserted, and then the grout material is placed between this tensile steel material and the inner wall of the Manchette tube or sleeve pipe. The method for constructing a double anticorrosion anchor is characterized in that the tensile strength is introduced into the tensile steel material after the filling and filling of the grout material are allowed to harden. 4. The method of constructing a double anticorrosion anchor according to claim 3, wherein the ground injection is performed a plurality of times through the manchette tube or the sleeve pipe by the injection pipe. 5. The method of constructing a double anticorrosion anchor according to claim 3, wherein a corrugated unevenness is formed on a part or all of the wall surface of the manchette tube or the sleeve pipe.