JPH0827788A - Anchor fixing body, its manufacture and anchor assemblage - Google Patents

Abstract

PURPOSE:To restrain frictional stress by tensile force by using an anchor fixing body formed by prestressed concrete previously given compression stress in the anchor lengthy direction. CONSTITUTION:A PC structure anchor fixing body 20 makes tubular structure provided with a plural number of holes 26 for anchor steel insertion and a grout insertion hole 28 of a central part, and a cylindrical reinforcing member 22 and a PC steel wire 24 are arranged in the inside of a tube wall. At the time of manufacture, firstly a void tube is inserted into a formwork to secure a void for the anchor steel insertion and grout injection, and a spacer or the reinforcing member is set in the formwork cocentrically after arranging the PC steel wire 24 with a specified interval. Thereafter, after filling and hardening high strength mortar while keeping to apply tensile force by way of fixing one end of the PC steel wire and stretching and fixing the other end, fixing of the PC steel wire is released. An anchor steel is fixed by providing a head end cap by way of inserting the anchor steel into the through hole 26 provided on such a PC structure anchor fixing body, and an anchor is inserted into s drilled hole after assembling anchor by way of integrating the anchor fixing body and the anchor steel before inserting it into the drilled hole at the time when a fixing lengthy part is short.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing member for a tension type anchor, and more particularly, to an anchor fixing member capable of preventing the occurrence of cracks due to the concentration of tensile stress in the fixing length portion, a method for producing the anchor fixing member, and the anchor fixing member. The method of assembling the used anchor.

[0002]

2. Description of the Related Art In recent years, anchors and anchor construction methods have been increasingly used as permanent anchors for stabilizing slopes, foundations and reinforcement of civil engineering and building structures.

An anchor generally has a free length portion and a fixing length portion, and the free length portion is a portion in which a tensile material freely expands in response to a tensile force, and the fixing length portion has a grout hardening agent around it. It is a part that is fixed to the ground around the drill hole by injecting. A PC steel rod or a PC stranded wire is usually used as the tensile material, that is, the anchor steel material.

Due to the difference in the tensile force transmission mechanism in the fixing length portion, it is roughly classified into a tension type anchor and a compression type anchor. In both types of anchors, the tensile force applied to the tensile member is transmitted from the tensile member to the grout and the ground through frictional resistance.

FIG. 5 is a structural schematic view of a general tension type anchor 10. FIG. 5A is a vertical sectional view of the whole,
FIG. 5B is a cross-sectional view of the fixing long portion. Anchor steel material 12, which is a tensile member, is passed through the central portion, and the free length portion thereof can freely expand with respect to tension, while the fixed length portion is fixed to the ground. The fixing length portion is usually provided with an anchor steel material 12 and a sheath material such as a corrugated sheath tube 14, and pouring grout 18 between the anchor steel material 12 and the sheath tube 14 and between the sheath tube 14 and the ground 16. Fixed by. Usually, the sheath tube 14 is provided mainly for preventing invasion of harmful substances such as water from the outside as described later. In addition, the surface shape of the sheath tube is also devised such that unevenness is provided in order to enhance the adherence to the grout 18.

Usually, a structure that surrounds the anchor steel material in the fixing length portion and fixes the anchor steel material to the ground is called an anchor fixing body or an anchor body. If there is a sheath tube, the anchor fixing body includes the sheath tube and the tubular grout injected into the space inside and outside the sheath tube. In the case where there is no sheath tube, it corresponds to a tubular grout solid body. In addition, as a method of forming the anchor fixing body,
First, the structural parts other than the grout part of the anchor are preassembled on the ground, and then, this is inserted into the drill hole at the site, and the grout is injected into the necessary part to complete the work.

A problem with a general anchor is that when the tensile member is tensioned, cracks are generated in the grout due to deformation or stress concentration due to tensile stress. With respect to cracks, a sheath tube is provided to prevent entry of harmful substances such as water from the outside. There is a possibility that the adhesion between the tensile member and the grout or the adhesion between the inner and outer surfaces of the sheath tube and the grout may be broken due to the stress concentration. The reason why the grout cannot withstand the stress and causes the cracks is that the tensile stress is not evenly distributed over the entire fixing length portion but is concentrated on a part thereof, and the tensile stress is generated due to the elongation of the tensile material.

FIG. 4 shows the distribution of frictional stress in the fixing length portion when tension is applied to the tension member of the anchor. When tension is applied to the tensile member, stress concentrates on the portion near the free length portion as indicated by I at the initial stage. Then, this stress sequentially moves to the bottom of the drill hole and reaches the end, as shown by II and III. This is because the elastic displacement or elongation of the tension material when tension is applied to the tension material first occurs in I,
It corresponds to passing on to II and III. The reason why the elongation is not instantaneously transmitted to the entire tensile member in the fixing length portion with respect to the tensile force is that the tensile member is firmly fixed to the solidified grout. Therefore, the stress is always concentrated on a part, so that the entire fixing long portion cannot contribute to the resistance, that is, the fixing force.

Several countermeasures have been proposed so far with respect to the above-mentioned crack generation due to stress concentration and the corrosion of the tensile member due to the crack generation. The main components are to reduce the occurrence of cracks, to provide a sheath tube, etc. so that harmful substances such as water do not enter even if a crack occurs, and to provide a sheath tube when a sheath tube is provided. For example, to strengthen the adhesion with the grout. Further, a configuration for avoiding the stress concentration itself and distributing the stress is also proposed.

At present, as described above, a large number of double-layered structures are provided in which a fixing tube is provided with a stainless steel or synthetic resin sheath tube, and a special structure is used to strengthen the connection between the sheath tube and the grout. As an example of providing a sheath tube having a different structure, Japanese Patent Publication No. 55-15569 and Japanese Patent Publication No.
40766 and Jitsuhei No. 3-24665.

In these patent applications or utility model registration applications, the fixing force between the sheath tube and the grout is strengthened by providing uneven structures of various shapes on one or both of the inner and outer surfaces of the sheath tube. However, these applications, which have a problem of strengthening the bond between the sheath tube and the grout, do not solve the stress concentration itself, and do not consider crack generation in the bond between the tensile member and the grout. Therefore, it is conceivable that the tensile material may come off due to the progress of grout cracks around the tensile material due to stress concentration.

Further, as an example in which the stress concentration itself is canceled to disperse the stress, Japanese Patent Publication No. 5-30932 is disclosed.
Japanese Patent Application Laid-Open No. 4-344911 and Japanese Patent Application Laid-Open No. 5-33.
There is 338. In Japanese Examined Patent Publication No. 5-30932, several U-turn portions are provided in the fixing long portion, and the steel wire hung on each U-turn portion is sequentially tensioned to distribute the stress. In this structure, cracks are less likely to occur in the anchor body because compressive stress is applied to the anchor body. This is called a compression / dispersion type anchor.

As another means for distributing stress, another embodiment of the above Japanese Patent Publication No. 5-30932 or JP-A-5-333 is disclosed.
As in No. 38, there is one in which stress is not concentrated as a whole by arranging a plurality of tensile members with their tip positions displaced. However, even in this structure, stress concentration is not avoided in the case of one steel wire, and again, crack generation in the bond between the steel wire and the grout is not considered. Further, the U-turn structure and the structure for shifting the tip position of the steel wire have complicated structure arrangements, but when tension is further applied to the steel wire, the steps must be strictly performed in order, and the process is complicated.

Further, in Japanese Patent Laid-Open No. 4-343911,
A structure is presented in which the sheath tube is divided in the length direction and the split sheath tubes are connected by an expandable joint sheath. As a result, since each split sheath tube acts as an independent sheath tube, the grout stress around the sheath tube is dispersed. However, in this case as well, since the bond between the tensile member and the grout is the same as the conventional one, the stress concentration in this part cannot be avoided.

Further, in Japanese Patent Publication No. 1-37533,
We presented a construction method in which the grout was partially injected into the fixing length part in several stages, and the tension material was tensioned and prestressed at each stage to distribute the stress in each stage. There is. This construction method has the drawbacks that the stress dispersion effect can be expected, but the process is complicated and takes a very long time.

[0016]

In many of the conventional techniques described above, a double structure is employed in which the entire anchor steel material is sealed with a corrosion-resistant material such as synthetic resin or stainless steel to prevent water from entering due to cracks. In most cases, the durability is further improved by strengthening the coupling with the grout via the sheath tube. Further, the structure and the process are also complicated for those which try to disperse by avoiding the stress concentration itself.

An object of the present invention is to provide an anchor fixing body which suppresses a frictional stress due to a tensile force of a tensile member and a method for manufacturing the anchor fixing body. Furthermore, an anchor is efficiently assembled using the anchor fixing body according to the present invention. Is to provide a method.

[0018]

The above object of the present invention is to:
It is realized by the following configuration.

(1) An anchor fixing member in an anchor for fixing a fixing long portion by a grout solidified body between the ground and a tension member at a ground end of the free length portion under a tension load condition, The anchor anchor of PC structure is characterized in that it is formed from prestressed concrete (PC) to which a compressive stress is applied by providing a steel wire rod which is pretensioned in the longitudinal direction of the anchor.

(2) In the anchor-fixing body according to (1) above, the prestressed concrete further has a net-like or spiral-like reinforcing member inside thereof, which is a PC-structure anchor fixing body.

(3) In the anchor fixing member according to any one of (1) and (2) above, a PC structure anchor fixing is characterized in that mesh-like or spiral irregularities are provided on the outer peripheral surface of the anchor fixing member. It is the body.

(4) A method of manufacturing an anchor fixing body in an anchor in which a fixed long portion is fixed by a grout solidified body between the ground and a tension member is fixed at a ground end of a free length portion in a tension load state. There, a mold for forming the anchor fixing member outer shape is installed, and a void tube for ensuring a tubular hollow is installed in the mold, and a space between the mold and the void tube. A plurality of PC steel materials at regular intervals, applying a tension force to the PC steel material and maintaining that state, after filling the space between the mold and the void pipe with concrete and hardening it, A method of manufacturing a PC structure anchor fixing body, which is characterized in that the PC structure anchor fixing body is formed from prestressed concrete which is pre-compressed by releasing tension and removing the mold.

(5) In the method for manufacturing a PC-structure anchor-fixing body according to the above (4), the PC-structure anchor-fixing body is further cut into a predetermined length and then subjected to anchor assembly. .

(6) A method of assembling an anchor using a PC structure anchor fixing member manufactured by the method according to any one of (4) and (5) above,
After inserting a predetermined number of PC steel wires as tensile members into the structural anchor fixing member, one end of the PC steel wires is fixed by attaching an anchor tip cap,
A first connecting member having a centerizer, an adhesive injection port, and an adhesive injection confirmation port is attached to a first position on the outer peripheral surface of the structural anchor fixing member, and the adhesive is injected from the tip, and the first connecting member is attached. The first step of filling the adhesive is completed with overflow from the adhesive injection confirmation port of the connection member of, and then the second connection member is attached to the second position above the first position, The adhesive is injected from the adhesive injection port of the first connecting member, and the second step of the adhesive filling is completed by overflow from the adhesive confirmation port of the second connecting member, and the second By repeating the same operation as the step,
An anchor assembly method comprising a step of integrating a structural anchor fixing body and a PC steel strand.

(7) In the method for assembling the anchor according to the above (6), after the step of integrating the first PC structure anchor fixing body and the PC steel stranded wire, the first PC structure anchor fixing body is formed. The method of assembling an anchor is characterized by including the steps of inserting into an excavation hole and thereafter overlapping and connecting one or a plurality of PC anchor anchor fixing members until a desired length is achieved in the excavation hole. .

[0026]

According to the present invention, since the anchor fixing body is formed of prestressed concrete (PC) which has been given a compressive stress in advance, even if the tensile force is transmitted to the anchor fixing body by tensioning the tension member, it is included. In a stress state smaller than the prestressed load, the stresses cancel each other out so that no crack occurs.

Further, since the PC structure anchor fixing member of the present invention has a uniform structure in the length direction, it can be mass-produced in accordance with an arbitrary length as a standard, and thereafter, it is formed into a desired length in use. It can be cut and used. That is, the anchor fixing body can be manufactured as a ready-made product.

Furthermore, in the PC anchor anchor fixing member according to the present invention, since the structure cut to an arbitrary length can be easily connected by using the connecting member, the short fixing members are sequentially inserted into the excavation holes and connected. Thus, it is possible to easily form a long fixing member. Further, this work does not require a work space for standing up the completed long fixing member to be inserted into the excavation hole, so that the work efficiency is good and the application range is wide.

[0029]

1 is a cross-sectional view of a PC structure anchor fixing member according to the present invention.

Conventionally, the periphery of the anchor steel material is fixed by a grout solidified body. As mentioned with respect to FIG.
With respect to the tensile force applied to the anchor steel material, stress is initially applied to the fixed length portion of the anchor steel material, which is close to the free length portion, and a slight elongation occurs. If this elongation is instantaneously transmitted to the entire tension material of the fixing length portion, stress is instantaneously transmitted and dispersed throughout. However, if the anchor steel is firmly attached to the solidified grout, this elongation will not be transmitted instantaneously beyond that. By further increasing the tensile force, this stress is slowly transmitted to the tip. Therefore, the stress is always concentrated on a part, so that the entire fixing long portion cannot contribute to the resistance, that is, the fixing force. Then, cracks occur in the grout around the anchor steel material in the portion where the stress is concentrated.

The PC structure anchor fixing member 20 according to the present invention shown in FIG. 1 is made of a prestressed concrete member. The structure is, for example, a tubular structure provided with a plurality of anchor steel material insertion holes 26 arranged as shown in FIG. 1 and a central grout injection hole 28, and a cylindrical reinforcing member inside the pipe wall. A member 22 (double in FIG. 1) and a PC steel wire 24 for prestressing the concrete member are arranged as shown. Reinforcement member 2
2 also has a role of a spacer for arranging the PC steel wires 24 at a constant interval, and is formed in a mesh shape or a spiral shape by, for example, a reinforcing bar.

Prestressed concrete is a well-known construction method in which a compressive stress is applied to the concrete in advance in order to compensate for the weakness of the concrete, which originally has the property of being weak in tensile strength. For example, it is used for concrete bridges and large aquariums. To give one of the general production methods, after installing several PC steel wires in a concrete formwork in an appropriate arrangement, concrete is placed in the formwork while tensioning the PC steel wire. Fill and solidify. After solidifying,
Compressive stress is introduced into the concrete by releasing both ends of the PC steel wire. The prestressed concrete thus formed has been previously subjected to a compressive force, and when the tensile force is applied by the load, the tensile force can be canceled.

In the present invention, the principle of this prestressed concrete is applied to the anchor fixing member.
In the present invention as well, by using the PC structure anchor fixing body containing the compressive stress in advance, it is possible to cancel the tensile force of the anchor steel material, so that it is possible to prevent the occurrence of cracks.

Further, in the present invention, the anchor fixing member 20 made of prestressed concrete having the structure shown in FIG.
The individual design length or standard length (for example, 1m, 1.5m
It is possible to uniformly manufacture a long product to some extent in a factory and cut it into a required length before use. That is, it is easy to select an arbitrary length. Further, this cutting work can be performed in the factory and also in the field. Therefore, it is possible to provide a highly versatile anchor fixing body as a ready-made product, and it is possible to efficiently manufacture the anchor fixing body, so that the cost can be reduced.

As shown in FIG. 1 (b), it is also possible to provide spiral or net-like irregularities around the anchor fixing member. These irregularities are for improving the stress transmissibility with the injection grout and for enhancing the filling property of the injection grout.

An example of the manufacturing procedure of the PC structure anchor fixing member of FIG. 1 will be described. First, a void tube is inserted into the mold to secure a hollow for inserting an anchor steel material and injecting grout. Then, after arranging the PC steel wires at regular intervals, spacers or reinforcing members are installed concentrically on the mold.
Then, tension is applied by fixing one end of the PC steel wire and pulling and fixing the other end. While the PC steel wire is under tension, it is filled with high-strength mortar and solidified. After solidification, the fixing of the PC steel wire is released to complete.

Next, FIG. 2 is a view for explaining a method of assembling an anchor using the PC structure anchor fixing member 20 according to the present invention. As described above, the anchor fixing member according to the present invention is cut into a desired length in a factory or an anchor construction site and then provided for assembly.

First, an anchor steel material (for example, PC steel stranded wire) is inserted into the through hole 26 for anchor steel material provided in the PC structure anchor fixing body 20, and the anchor steel material is fixed by installing a tip cap.

In the case of a short anchor having a fixing length of about 3 to 4 m, the anchor fixing member and the anchor steel material are integrated before the excavation hole is inserted to assemble the anchor and then inserted into the excavation hole. To do. FIG. 2 is a plan view and a side view of an anchor fixing body equipped with a connecting member for integrating the anchor fixing body and the anchor steel material. When the PC structure anchor fixing body 20 and the anchor steel material are integrated,
The connecting member 30 as shown in FIG. 2A is fitted in several places on the outer periphery at appropriate intervals. The connecting member 30 is easily fitted by including the rotating roller 32, and also serves as a centerizer for holding the anchor fixing body 20 in the central portion of the drill hole. Further, the connecting member 30 is provided with a hole 34 for injecting the adhesive and confirming the injection.

Next, the adhesive is injected into the anchor fixing member from the tip portion, and the adhesive filling is completed when the adhesive overflows from the injection confirmation port 34 of the connecting member. Similarly, the PC structure anchor fixing member and the anchor steel material are integrated by injection and filling. After that, the assembled anchor is inserted into the excavation hole and fixed to the ground by grout injection.

However, when the fixing length is close to 10 m, the work of inserting the preassembled one into the excavation hole becomes very difficult. The space required to set up the anchor is large and difficult to handle. In the case of such a long length, first, the short first PC anchor fixing member assembled by the method described with reference to FIG. 2 is inserted into the drill hole. The second PC structure anchor fixing member is further inserted thereon so as to be connected to each other and injected and solidified. In this way, the PC-structure anchor fixing bodies are connected and solidified in the excavation hole until a predetermined length is obtained, and a long anchor is completed.

FIG. 3 is an overall structural view in which an anchor using the PC structure anchor fixing member according to the present invention is constructed. In the fixing length portion, a PC structure anchor fixing body 20, a connecting member (centerizer) 30 provided on the outer periphery thereof, and a tip cap 40 are arranged as illustrated. It is fixed to the surrounding ground by injecting grout around the PC structure anchor fixing body 20 held in the center of the drill hole by the centerizer 30.

[0043]

According to the present invention, since the anchor fixing member is formed of prestressed concrete, the precompressive force contained in the prestressed concrete cancels and suppresses the tensile stress generated when the anchor steel material is tensioned. It Further, since stress concentration is avoided, the occurrence of cracks due to this is prevented, and the anchor steel material can be protected from corrosion. Thus, a reliable and permanent tension anchor is provided.

Further, the PC structure anchor fixing member according to the present invention can be manufactured after being manufactured to a uniform standard in a factory and then cut into a desired length in a factory or on-site, which is very simple. It can be used efficiently and can be manufactured at low cost. Further, when the PC structure anchor fixing member according to the present invention is long, it is possible to perform the connecting work in the excavation hole, so that the workability is good and a wide working space is not required.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a PC structure anchor fixing member according to the present invention.

FIG. 2 is a diagram showing a method of assembling an anchor using a PC structure anchor fixing member according to the present invention.

FIG. 3 is an overall configuration diagram showing an example of construction of an anchor using a PC structure anchor fixing body according to the present invention.

FIG. 4 is a schematic configuration diagram of a general tension anchor.

FIG. 5 is a diagram showing a frictional stress distribution of an anchor fixing member.

[Explanation of symbols]

 14 sheath tube 16 ground 18 grout 20 anchor anchoring body 22 intermediate layer 30 injection port 32 reinforcing agent

Claims (7)

[Claims] 1. An anchor fixing body in an anchor for fixing a fixed length portion by a grout solidified body between the ground and a ground material of a free length portion and fixing a tension member in a tension load state, wherein the anchor An anchor fixing body having a PC structure, which is formed from prestressed concrete (PC) to which a compressive stress is applied by providing a steel wire rod which is pretensioned in the longitudinal direction thereof. 2. The anchor fixing member according to claim 1, wherein the prestressed concrete further has a net-like or spiral-like reinforcing member inside.
Structural anchor fixing body. 3. An anchor fixing body according to claim 1, wherein the anchor fixing body is provided with mesh-like or spiral irregularities on an outer peripheral surface thereof. 4. A method for producing an anchor fixing body in an anchor, wherein a fixed long portion is fixed by a grout solidified body between the ground and a tension member is fixed in a tension load state at a ground end of a free length portion. A mold for forming the anchor-fixing body outer shape is installed, and a void tube for securing a tubular hollow inside the mold is installed, and in a space between the mold and the void tube. A plurality of PC steel materials are arranged at regular intervals, a tension force is applied to the PC steel materials and the state is maintained, and the space between the form frame and the void pipe is filled with concrete and hardened, and then the tension is applied. Formed from prestressed concrete which has been prestressed by releasing the force and removing the formwork P
C structure anchor fixing body manufacturing method. 5. The method for manufacturing a PC structure anchor fixing body according to claim 4, after further cutting to a predetermined length,
A method for manufacturing a PC-structured anchor fixing member, which is used for anchor assembly. 6. A method for assembling an anchor using a PC structure anchor fixing body manufactured by the method according to claim 4 or 5, wherein the PC structure anchor fixing body is a tensile member. After inserting a predetermined number of PC stranded wires, one end of the PC stranded wires is fixed by attaching an anchor tip cap, and a centerizer is provided at a first location on the outer peripheral surface of the PC structure anchor fixing body. A first connection member having an adhesive injection port and an adhesive injection confirmation port is attached, the adhesive is injected from the tip, and the adhesive is caused by overflow from the adhesive injection confirmation port of the first connection member. Completing the first stage of filling, then mounting a second connecting member at a second location above the first location, and injecting an adhesive from the adhesive injection port of the first connection member. And the second connecting member By having the overflow from the adhesive confirm port to complete the second phase of the adhesive filling, and the same operation is repeated with the second stage, P
An anchor assembling method comprising a step of integrating a C structure anchor fixing body and a PC steel strand. 7. The anchor assembly method according to claim 6, wherein after the step of integrating the first PC structure anchor fixing body and the PC steel strand, the first PC structure anchor fixing body is excavated. An anchor assembling method, which comprises the steps of inserting the anchor structure into one of a plurality of PC anchor anchors and inserting the anchor anchor members into the hole until they have a desired length.