JP2008274730A - Pull-out force increasing method for ground anchor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pull-out force increasing method for a ground anchor, for solving the problem wherein an anchor adhering to a stable ground is often pulled out, and it is considered to result from that an anchoring body is biased to the lower side of a bored hole to make the contact area with an anchoring material insufficient, and further the frictional force to the hole wall is insufficient due to the bad quality of the anchoring material is poor in quality, and on the other hand, it is considered to be a little affected by that when large tension is required, naturally a tendon is increased in thickness so that a difference in level from the anchoring body is eliminated to decrease the bearing sectional area at the front of the anchoring body. <P>SOLUTION: (1) The anchoring body and the tendon are installed in the center of the bored hole by this developed press-in friction device, a clasp type center lift device and a guide hole. (2) In a casing, a friction plate is pressed in between the hole wall and a moving frame through the clasp type center lift raised in the bored hole. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

Detailed Description of the Invention

  The present invention relates to pulling up a ground anchor (hereinafter referred to as an anchor).

  As shown in Fig. 1, the anchor is a landslide block that is going to be active. One end of a tension member called tendon is fixed to the stable ground of the borehole with a fixing material such as cement, and the reaction force is taken. It is fixed to a concrete structure or a pressure plate on the surface of the earth to suppress sliding activity.

  The anchor is installed by drilling from the ground surface to the stable ground by mechanical boring, etc., and then filling the boring hole with a fixing material. Then, a wire or the like is inserted from the PC steel, which is a tendon, into the boring hole. Then, tendon is integrated with the hardened fixing material to form an anchor body and adhere to the borehole wall. The tendon on the surface is tensioned with a jackie and fixed to a concrete structure or pressure plate. The tension force of the tendon prevents the sliding soil block with a concrete structure or pressure plate and tightens the sliding surface.

  However, the anchor attached to the stable ground may come off. As shown in FIG. 2, the cause is considered that the anchor fixing body is biased under the boring hole and the contact area with the fixing material is insufficient, or the frictional force with the hole wall is insufficient due to the poor quality of the fixing material. ing. In addition, when a large tension is required, the tendon naturally becomes thicker, the level difference with the fixing body is reduced, and the bearing cross-sectional area on the front surface of the fixing body is reduced. Note that the fixing body is obtained by covering an anchor fixing section at the tip of the tendon (hole bottom side) with a steel or plastic pipe with unevenness to increase the frictional force.

  As a method for solving the above-described problem, in addition to the frictional force with the conventional borehole wall, the borehole in the section forming the anchor body is greatly drilled (expanded), and the outer ring piece outside the fixing body is jacked. A method has been developed in which the tendon is expanded by the wedge principle when the tendon is tensioned, and the anchor pulling force is increased by the passive earth pressure of the cross section of the expanded portion. (Japanese Patent No. 2673896) Recently, in order to increase the contact area of the fixing body, the Anchor Association has increased the diameter of the hole by one round (for example, the nominal diameter of the hole is 90 mm → 115 mm). However, in order to obtain a stable anchor pulling force, it is necessary to bring the fixing member to the center of the boring hole and increase the frictional force between the fixing member and the hole wall by some method.

Problems to be solved by the invention

However, both conventional methods have a large cost because the diameter of the drilling hole is large, and the hole expansion type is particularly expensive. The former hole + wedge type has a complicated structure, and the wedge only expands the outer ring piece and does not act on the pressure of the hole wall. Therefore, the anchor pull-out force is not increased at a higher cost. As for the latter, the environment of the fixing body in the anchor hole (the lack of frictional force with the hole wall of the anchor fixing body) has not changed.

  Therefore, in order to develop an anchor with a reliable pull-out force and low price, it is necessary to install the fixing body at the center of the boring hole by some method to increase the frictional force between the fixing body and the hole wall.

Means for solving the problem

  The inventor considered two things as a method for solving the above-mentioned problems. One method for bringing the fixing body (10) and tendon (6) to the center of the boring hole (5) uses T2007H19-1, T2007HH19-2 and T2007H19-3 developed by the same inventor. Second, something (friction plate) is inserted into the gap between the fixing body (10) and tendon (6) and the boring hole (5). They are installed by operating the device when the casing (9) is pulled out. Thus, the principle of the prayer-type center lift device (16) of T2007HH19-2 is applied to laying the apparatus of the present invention.

  FIG. 3 is a cross-sectional view of the device inserted into the casing before operation. After the boring hole (5) has been drilled, the fixing material (11) is filled into the casing (9). Into the casing (9), the fixing body (10) and the tendon (6) to which the press-fitting type friction device (17) and the prayer type center lift device (16) as the device of the present invention are attached are inserted. This device is initially restrained in the casing (9), but when the casing (9) is pulled out, the two devices are actuated when opened. The friction plate (17-a) and the movable frame (17-b) are engaged with each other through a groove. Further, a groove for inserting a drop-off prevention material is cut on the outer periphery of the friction plate (17-a) and the movable gantry (17-b), and a rubber band or the like rich in elasticity is put in and pressed lightly. Further, the friction plate (17-a) and the movable frame (17-b) are divided into 3 to 4.

  The method for increasing the pulling-out force of the anchor according to the present invention is as shown in FIG. 3, and the press-fitting friction device (17) and the worship type center lift device (16) inserted into the casing (9) When it is pulled out, first, the movable frame (17-b) is opened. Then, the coil spring (16-b) is opened, and the force is transmitted to the worship type center lift (16-e) ⇒ friction plate (17-a) ⇒ moving stand (17-b), and the moving stand (17-b) Pushed by the friction plate (17-a), the inclination of the receiving stand (17-c) rises, and as shown in FIG. 4, the convex (17-d) inside the moving stand (17-b) The movement is stopped by fitting in the recess (17-e) outside the cradle (17-c). Further, when the casing (9) is pulled out, the friction plate (17-a) is opened. Then, the coil spring (16-b) further expands, and the friction plate (17-a) also rises the inclination of the movable frame (17-b) by that force, and finally stops against the hole wall (5). Next, when the prayer center lift (16-e) is opened, it is also pushed by the force of the coil spring (16-b), bent from the lift shaft (16-f), and moved toward the hole wall (5). spread. The expanded center lift (16-e) is pushed toward the bottom of the hole by the casing (9), and the friction plate (17-a) is moved to the hole wall (5) and the receiving base (17-c) as shown in FIG. Press fit between.

Action

  All of the press-fitted friction device (17) and the worship type center lift device (16) of this device were operated and spread to the hole wall side. When the expanded prayer center lift is pushed toward the bottom of the hole with the casing, the friction plate is press-fitted between the hole wall and the cradle as shown in FIG. 5, and the developed anchor is shown in FIG. Was installed. However, the tip cap (8) of the fixing body (10) is inserted into the guide hole (18) drilled by the inner bid and installed at the center of the boring hole. See patent application (T2007H19-1).

An embodiment of the present invention will be described based on an example.
The inventor considered two things as a method for solving the above-mentioned problems. One method for bringing the fixing body (10) and tendon (6) to the center of the boring hole (5) is to use patent applications (T2007H19-1, T2007HH19-2, T2007H19-3) developed by the same inventor. . Second, something (friction plate) is inserted into the gap between the fixing body (10) and the tendon (6) and the boring hole (5). They are installed by operating the device when the casing (9) is pulled out. Then, the principle of the worship type center lift device (16) of T2007HH19-2 is applied to laying the apparatus of the present invention.

  FIG. 3 is a cross-sectional view of the device inserted into the casing before operation. After the boring hole (5) has been drilled, the fixing material (11) is filled into the casing (9). Into the casing (9), the fixing body (10) and the tendon (6) to which the press-fitting type friction device (17) and the prayer type center lift device (16) as the device of the present invention are attached are inserted. This device is initially restrained in the casing (9), but when the casing (9) is pulled out, the two devices are actuated when opened. The friction plate (17-a) and the movable frame (17-b) are engaged with each other through a groove. Further, a groove for inserting a drop-off prevention material is cut on the outer periphery of the friction plate (17-a) and the movable gantry (17-b), and a rubber band or the like rich in elasticity is put in and pressed lightly. Further, the friction plate (17-a) and the movable frame (17-b) are divided into 3 to 4.

  The method for increasing the pulling-out force of the anchor according to the present invention is as shown in FIG. 3, and the press-fitting friction device (17) and the worship type center lift device (16) inserted into the casing (9) When it is pulled out, first, the movable frame (17-b) is opened. Then, the coil spring (16-b) is opened, and the force is transmitted to the worship type center lift (16-e) ⇒ friction plate (17-a) ⇒ moving stand (17-b), and the moving stand (17-b) The protrusion (17-d) on the inner side of the movable frame (17-b) as shown in FIG. The movement is stopped by fitting in the recess (17-e) outside the cradle (17-c). Further, when the casing (9) is pulled out, the friction plate (17-a) is opened. Then, the coil spring (16-b) further expands, and the friction plate (17-a) also rises the inclination of the movable frame (17-b) by that force, and finally stops against the hole wall (5). Next, when the worship type center lift (16-e) is opened, it is also pushed by the force of the coil spring (16-b), bent from the lift shaft (16-f), and moved toward the hole wall (5). spread. The expanded center lift (16-e) is pushed to the bottom of the hole by the casing (9), and the friction plate (17-a) is moved to the hole wall (5) and the receiving stand (17-c) as shown in FIG. Press fit between.

The invention's effect

  First, the press-fitting friction device + worship type center lift device + guide hole that expands into the bore hole, the fixing body and tendon are installed at the center of the bore hole, and the fixing material is evenly filled around the fixing body. The frictional force between the borehole wall and the fixing body increased. Next, when the friction plate is press-fitted between the hole wall and the movable frame via a prayer center lift that rises in the boring hole, the frictional force between the boring hole wall and the fixing body is increased. The cross section of the front surface of the fixing body is enlarged due to the expansion of the friction plate, and the resistance to the fixing material is greatly increased.

Ground anchor laying diagram Fixing body and tendon laying diagram Cross section before press-fitting friction machine operation Cross-sectional view after operation of press-fit friction device Cross section after operation of press-fit friction machine Overall view of press-fit friction device

Explanation of symbols

1. Ground surface 17. 1. Press-fit friction machine Moving mass 17-a. Friction plate (press-fit plate)
3. Sliding surface 17-b. Mobile stand 4. Stable ground 17-c. 4. Support stand Boring hole and hole wall 17-d. Convex 6. Tendon 17-e. Concave 6-1. Sheath 17-f. 6. Detent groove Spacer 18. Guide hole 8. Tip cap 9. Casing 10. Fixing body 11. Fixing material (cement milk, mortar, etc.)
12 Cured fixing material13. Pressure plate A. Anchor head 14. Supporting plate B. Anchor free length15. Anchor head C.I. Anchor anchor length16. Worship Center Lift Device D. Anchor length 16-a. Reaction table 16-b. Coil spring 16-c. Stress transmission plate 16-d. Detent 16-e. Worship Center Lift 16-f. Lift shaft 16-g. Protrusion 16-h. Ring and delivery groove

Claims (2)

  In the press-fitting friction device (17) and the prayer-type center lift device (16) inserted into the casing (9), when the casing (9) is gradually pulled out, first, the movable frame (17-b) is opened. The Then, the coil spring (16-b) is opened, and the force is transmitted to the worship type center lift (16-e) ⇒ friction plate (17-a) ⇒ moving stand (17-b), and the moving stand (17-b) The protrusion (17-d) on the inner side of the movable frame (17-b) as shown in FIG. The movement is stopped by fitting in the recess (17-e) outside the cradle (17-c). Further, when the casing (9) is pulled out, the friction plate (17-a) is opened. Then, the coil spring (16-b) further expands, and the friction plate (17-a) also rises the inclination of the movable frame (17-b) by that force, and finally stops against the hole wall (5).   The expanded prayer type center lift (16-e) is pushed to the bottom of the hole by the casing (9), and the friction plate (17-a) is moved to the hole wall (5) and the receiving stand (17-c) as shown in FIG. Press fit between.

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