JP4203566B2 - Lock bolt pull-out resistance test apparatus and lock bolt pull-out resistance test method - Google Patents

Description

  The present invention relates to a drawing resistance test apparatus for measuring the drawing resistance strength of a steel pipe expansion type rock bolt inserted and expanded in a hole provided in a rock mass, and a drawing resistance test method using the apparatus.

Conventionally, as a method to reinforce natural ground and cut slopes, or as a tunnel support method, rod-shaped rock bolts are inserted into the ground, and grout material is injected and solidified around it. A method for strengthening the ground by integrating is known.
In such a ground strengthening method, in order to confirm the degree of strengthening, a pulling resistance test is performed in which an embedded rod-like lock bolt is pulled out to check its pulling resistance. As the test apparatus, there has been proposed a drawing resistance test apparatus for testing the pulling resistance strength of a steel bar member inserted and installed in a natural ground (see, for example, Patent Document 1).

By the way, in recent years, tubular steel pipe expansion type lock bolts have come to be used in order to solidify rocks and grounds that tend to collapse instead of conventional bar-shaped lock bolts (see, for example, Patent Document 2).
A steel tube lock bolt with a recess for expansion in the longitudinal direction, closed at the tip and covered with a sleeve for high-pressure water injection at the rear end is inserted into a hole provided in the bedrock and drilled in the side of the sleeve. In addition, high pressure water is injected from the high pressure water injection hole, and the steel pipe is pressurized and expanded to adhere to the hole wall so as to consolidate the rock and ground with the steel pipe.
Even when such a tubular steel pipe expansion type lock bolt is used, it is naturally necessary to perform a pulling resistance test. However, the drawing resistance test apparatus described in Patent Document 1 is an apparatus for testing the pulling resistance strength of the steel bar member, and therefore cannot be used for the pulling test of the steel pipe expansion type lock bolt.

Therefore, a simple type pulling resistance test apparatus as shown in FIG. 1 has been proposed.
In this apparatus, first, after the sleeve chuck jig 1 is attached to the sleeve S attached to the steel pipe expansion type lock bolt R, the tension rod 2 is fastened to the sleeve chuck jig 1 to thereby form the sleeve chuck jig 1. Is fixed to the sleeve S. After that, the flattening casing 3 is put on the sleeve chuck jig 1 with the tension rod 2 penetrated, and the adjuster bolt 4 is adjusted to perform flattening, and then the height adjusting spacer 5 is mounted on the tension rod 2. Set in. Then, the center hole jack 6 is set in the tension rod 2. A stopper screw 7 is attached to the tip of the tension rod 2 and tightened. The sleeve S when pressure oil is fed into the center hole jack 6 by a manual hydraulic pump (not shown) and a pulling force is applied to the sleeve S attached to the steel pipe expansion lock bolt R via the tension rod 2. Attempts have been made to measure the pulling resistance strength from the displacement of the head.

Japanese Patent Laid-Open No. 2001-3700 Japanese Patent Publication No.2-5238

  However, if a pulling resistance strength test is to be performed using the apparatus as described above, it is necessary to first attach a sleeve chuck jig to the sleeve. As shown in FIG. 2, the conventional chuck mechanism of the sleeve chuck jig is designed to bite the claw 11 shown in FIG. 2B by tightening the tension rod 2. Thus, one person receives a reaction force at the outer portion of the sleeve chuck jig, and the other person performs the work of tightening the tension rod 2. In FIG. 2B, reference numeral 12 denotes a soft resin molded body, and the nail 11 and the soft resin 12 constitute a chuck die 13 (see FIG. 2A).

Next, the facing casing 3, the height adjusting spacer 5, and the center hole jack 6 are passed through the tension rod 2, and the stopper screw 7 is temporarily fastened. After adjusting the surface with the four adjuster bolts 4, the stopper screw 7 at the tip of the tension rod 2 is fastened, the center hole jack 6 is operated, and the steel pipe expansion lock bolt R is connected via the tension rod 2. A pulling force is applied to the attached sleeve S.
At this time, since the work of attaching the sleeve chuck jig to the sleeve S is manual and requires a considerable amount of force, the chuck force is insufficient, slipping occurs during the load test, and the pull-out test needs to be repeated. There is a case. In this case, it is necessary to remove and reattach each component and device in the reverse procedure to the above, which requires a great deal of labor and time.
As described above, in the test apparatus provided with the conventional sleeve chuck jig, there is a limit in the number of lock bolts that can perform the pulling resistance strength test.

  The present invention has been devised to solve such problems, and the sleeve chuck element has a simple structure, is easy to operate, improves the workability, and improves the pulling resistance strength for the lock bolt. An object is to provide a test apparatus.

In order to achieve the object, the lock bolt pull-out resistance test apparatus of the present invention comprises a collet chuck having an annular convex portion on the inner surface and a casing disposed on the outer periphery of the collet chuck for tightening the collet chuck. A sleeve chuck jig, a tension rod connected to the sleeve chuck jig, a flattening housing surrounding the sleeve chuck jig and the tension rod, and disposed on an upper surface of the flattening housing and penetrates the tension rod It is characterized by having a center hole jack.
An annular recess is provided in the sleeve for high-pressure water injection attached to the steel pipe expansion type lock bolt, and the annular protrusion provided on the inner surface of the collet chuck of the lock bolt pull-out resistance test device of the present invention is fitted into the annular recess of the sleeve. After the alignment, the casing is moved to tighten the collet chuck, and then a lock bolt pull-out resistance test is performed.

  In the lock bolt pull-out resistance strength test device of the present invention, the sleeve chuck jig is composed of a collet chuck having an annular protrusion on the inner surface and a casing for tightening the collet chuck disposed on the outer periphery of the collet chuck. It is composed. For this reason, the apparatus is miniaturized and the conveyance and handling are simplified. Therefore, the work of performing a pulling resistance strength test by mounting on lock bolts having poor scaffolding and various placement directions such as in a tunnel can be performed in a short time. Moreover, since the annular convex portion of the collet chuck is fitted into the annular concave portion of the high-pressure water injection sleeve attached to the steel pipe expansion type lock bolt, there is no possibility of occurrence of slip due to insufficient chucking force as in the conventional method. Therefore, the accuracy of the measurement value is improved, and the reliability of the test is greatly improved.

Pullout resistance test for a lock bolt according to the present invention, incorporating a sleeve chuck jig comprising a collet chuck provided with an annular protrusion on the inner surface and a casing for tightening the collet chuck arranged on the outer periphery of the collet chuck A preferred embodiment of the apparatus will be described.
Basically, the pull-out resistance test device for a lock bolt of the present invention is obtained by changing the sleeve chuck jig 1 of the conventional device as shown in FIG. 1 into a compact and easy-to-handle shape. This will be specifically described with reference to FIGS. A sleeve chuck jig C is fixed to the tip of the tension rod 2. The sleeve chuck jig C of the present invention includes a collet chuck 8 provided with an annular convex portion 9 on the inner surface, and a casing 10 disposed on the outer periphery of the collet chuck 8 for fastening the collet chuck 8. .
In a preferred form of the lock bolt pull-out resistance test device of the present invention, the flattening housing 3 surrounding the sleeve chuck jig C and the tension rod 2 connected to the sleeve chuck jig C, and the flattening housing 3 are disposed on the upper surface. And the center hole jack 6 which penetrated the said tension rod 2 is installed as shown in FIG. A stopper screw 7 for restricting the upper limit position of the center hole jack 6 is attached to the tip of the tension rod 2.

The collet chuck 8 provided with the annular convex portion 9 on the inner surface, for example, pierces the cylindrical body leaving the annular convex portion on the inner peripheral surface, and then digs a plurality of dividing grooves in the axial direction, and then opens. The diameter is increased to increase the inner diameter of the tip. It can be manufactured by applying a heat treatment such as quenching in the expanded state. As a material, it is preferable to use high-strength steel such as SCM440.
The shape of the casing 10 is not particularly limited as long as it is a cylindrical body having an inner diameter that can accommodate the collet chuck 8.

The collet chuck 8 is in a steady state in which the tip opening is expanded in diameter, and the casing 10 disposed on the outer periphery thereof is moved forward in the axial direction (leftward in the figure) in FIG. The end portion of the casing 10 fitted to the outer peripheral taper portion of the collet chuck 8 compresses the expanded diameter portion of the collet chuck 8 radially inward. As a result, the sleeve S attached to the steel pipe expansion lock bolt R is gripped by the collet chuck 8. In the figure, P is a bearing plate for integrating the lock bolt and the sprayed concrete and transmitting the stress accompanying the displacement of the inner wall surface of the tunnel to the lock bolt.
On the contrary, the release of the gripping is performed by moving the casing 10 rearward in the axial direction (rightward in the drawing) in FIG. When the end portion of the casing 10 is separated from the outer peripheral tapered portion of the collet chuck 8, the force that has compressed the tapered portion radially inward is released. As a result, the collet chuck 8 is expanded and restored radially outward by its own spring force, so that the inner diameter is expanded and the annular convex portion 9 of the collet chuck 8 is disengaged from the annular concave portion U of the high-pressure water injection sleeve S of the lock bolt.
For the purpose of facilitating the movement of the casing 10 in the axial direction and the locking mechanism at the moved position, the casing 10 has a rear end portion (right end in FIG. 3) and a collet chuck 8 rear end portion. It is preferable to provide a threaded portion and fit the two together.

The greatest feature of the present invention is that an annular convex portion 9 is provided on the inner surface of the collet chuck 8. The convex portion 9 is fitted into a concave portion U provided in an annular shape on the outer surface of the sleeve S attached to the steel pipe expansion type lock bolt R, and the sleeve S is securely gripped by the tightening action of the casing 10.
Since the tightening by the casing 10, that is, the axial movement of the casing 10 is performed by human power, the tightening force may change when an operator changes. However, by adopting the structure as described above, even if there is a slight difference in the tightening force, that is, a slight difference in the amount of movement of the casing 10 in the axial direction, the difference can be absorbed and the gripping position can be reliably set. It can be secured.
Therefore, even if the worker is replaced, high accuracy can be maintained, and a reliable lock bolt pull-out resistance test can be performed.

Next, the aspect which implements the pull-out test of the steel pipe expansion type lock bolt using the lock bolt pull-out resistance test apparatus of the said aspect is demonstrated.
First, the casing 10 constituting the sleeve chuck jig C is moved rearward in the axial direction (rightward in the drawing) in FIG. 3 to expand the tip of the collet chuck 8.
Thereafter, the expanded collet chuck 8 is put on the sleeve S attached to the steel pipe expansion lock bolt R, and the annular convex portion 9 formed on the inner surface of the collet chuck 8 is fitted into the annular concave portion U provided on the outer surface of the sleeve S. After matching, the casing 10 arranged on the outer periphery of the collet chuck 8 is moved axially forward (leftward in the figure) in FIG. 3 to compress the expanded portion of the collet chuck 8 radially inward, The collet chuck 8 grips the sleeve S attached to the steel pipe expansion lock bolt R.

  After that, the flattening casing 3 is put on the sleeve chuck jig with the tension rod 2 passing through, and the adjuster bolt 4 is adjusted to perform flattening, and then the center hole jack 6 is inserted into the tension rod 2. ,set. A stopper screw 7 is attached to the tip of the tension rod 2 and tightened to set the upper limit position of the center hole jack 6. The sleeve S when pressure oil is fed into the center hole jack 6 by a manual hydraulic pump (not shown) and a pulling force is applied to the sleeve S attached to the steel pipe expansion lock bolt R via the tension rod 2. The displacement of the head is measured via a tension rod or the like directly connected to the sleeve S, and the pulling resistance strength is known from the measured value.

After the drawing resistance strength can be measured, the pressure oil is discharged from the center hole jack 6, the stopper screw 7 is removed, and then the center hole jack 6 is removed from the tension rod 2. Further, after removing the flattening casing 3 from the tension rod 2, the casing 10 of the sleeve chuck jig C is moved rearward in the axial direction (rightward in the figure) in FIG. 3, and the collet chuck 8 is moved to its own spring. The sleeve S is released from the radial direction by force and released.
With this series of operations, the measurement of the pullout resistance strength of one steel pipe expansion type lock bolt is completed, and the next lock bolt pullout resistance test is started.
The lock bolt pull-out resistance test apparatus and lock bolt pull-out resistance test method of the present invention can be used for a pull-out resistance test of a steel bar type lock bolt by attaching an appropriate adapter.

  As described above, the sleeve chuck jig is composed of a collet chuck having an annular protrusion on the inner surface and a casing that is disposed on the outer periphery of the collet chuck and fastens the collet chuck. By fitting the annular convex part of this collet chuck into the annular concave part of the sleeve attached to the steel pipe expansion type lock bolt, the measurement value of the pull-out resistance strength test for the lock bolt is improved, and the weight of the device itself is reduced. -Combined with downsizing, a highly reliable extraction resistance strength test can be performed efficiently.

The figure explaining the drawing resistance strength test mode for rock bolts Sectional drawing explaining the conventional sleeve chuck | zipper aspect Sectional drawing explaining the sleeve chuck jig | tool structure of the drawing resistance strength test apparatus for rock bolts of this invention Sectional drawing explaining the aspect which fixes the sleeve for high-pressure water injection | pouring with a sleeve chuck jig | tool, and performs a pull-out resistance test of a lock bolt

Explanation of symbols

R: Steel pipe expansion type lock bolt S: Sleeve U: Annular recess provided in the sleeve
1: Sleeve chuck jig 2: Tension rod 3: Casing for flattening 4: Adjuster bolt 5: Spacer for height adjustment 6: Center hole jack 7: Screw for stopper 8: Collet chuck 9: Annular convex part 10: Casing

Claims (2)

  A sleeve chuck jig comprising a collet chuck having an annular protrusion on the inner surface and a casing disposed on the outer periphery of the collet chuck to tighten the collet chuck, a tension rod connected to the sleeve chuck jig, and the sleeve A pull-out resistance for a lock bolt comprising a flattening housing surrounding a chuck jig and a tension rod, and a center hole jack disposed on an upper surface of the flattening housing and penetrating the tension rod. Test equipment.   To form an annular recess in the high-pressure water injection sleeve attached to the steel pipe expansion type lock bolt, and to place the annular projection on the inner surface and the outer periphery of the collet chuck to tighten the collet chuck A sleeve chuck jig comprising a casing, a tension rod connected to the sleeve chuck jig, a flattening housing surrounding the collet chuck portion and the tension rod, disposed on an upper surface of the flattening housing, and After fitting the annular projection provided on the inner surface of the collet chuck of the pull-out resistance test device for a lock bolt equipped with a center hole jack through which the tension rod penetrates into the annular recess of the sleeve, the center hole jack is A lock characterized by being driven Bolt pull-out resistance test method.

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