JP2006299546A - Rock bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set rock bolt proof strength according to ground conditions by on-site design, and at the construction stage, sufficiently secure lock bolt pull-out strength at an early stage until the strength of the fixing material holding the lock bolt appears. To do.
SOLUTION: A lock bolt main body has a weight-like portion with a predetermined interval in the longitudinal direction of the lock bolt main body, for example, an outer shape that is pointed toward the back of the hole into which the lock bolt main body is inserted. A node-shaped anchor-shaped lock bolt in which a node anchor is retrofitted by direct contact with a predetermined position on the surface or by casting with a placed mold.
[Selection] Figure 1

Description

  The present invention relates to a lock bolt, and relates to a lock bolt in which a node anchor is provided at a predetermined interval in a lock bolt portion so that sufficient adhesion between the node anchor and a fixing material is achieved.

  In general, when constructing a tunnel by the mountain method, shot concrete, rock bolts, and steel support are the main ways to effectively utilize the support function of the ground surrounding the tunnel and stabilize the natural ground after excavation. Secured as a support member. Of these, the lock bolts are roughly classified into a full fixing method, a friction fixing method, and a combination thereof. Among these, the lock bolt by the full fixing method is a method of fixing the entire length of the lock bolt to the natural ground with a fixing material such as a steel anchor and cement mortar, the type and strength of the natural ground, the material and shape of the rock bolt, The effect of the lock bolt depends on the strength and age of the fixing material. Ensuring the effect of rock bolts early after excavation will make the most of the support function of the ground surrounding the tunnel, improving the excavation cycle and enabling high-speed tunnel construction. In addition, since the effect of the lock bolt increases, the steel support work can be omitted, leading to cost reduction of the tunnel construction. In addition, this construction method is indispensable for realizing a single shell.

  Conventionally, as the full-bonding type lock bolt, a torsion bar, a deformed bar, or a full thread bar having a steel anchor length of 3 m or 4 m and a diameter of 21 to 25 mm is adopted depending on the natural ground condition. In addition, the fixing material construction method includes a filling type that mainly uses cement mortar and an injection type that mainly uses cement milk depending on the ground condition. In any case, since the face is excavated immediately after the construction of the rock bolt in the excavation cycle, it is necessary to develop the effect as an anchor at an early stage. Until the strength of the fixing material was fully expressed, the maximum drawing load was different due to the difference in the surface shape of the steel anchor, and the torsion bar was larger than the deformed bar, but the effect was not sufficient.

  In view of this, a lock bolt has been proposed in which the surface shape of a steel anchor is devised to prevent adhesion breakage and to secure adhesion after the fixing material is cured (Patent Document 1). This lock bolt is formed by forming a screw node portion in a short range with a predetermined interval on a conventional torsion bar steel, and by alternately providing a coarse node pitch section of the torsion bar steel and a dense section of the screw node section alternately. The adhesion of the fixing material in the semi-curing stage and the adhesion with the fixing material after curing are secured.

  In addition, in the hot rolling stage, a rock bolt having a predetermined volume ratio on the surface of the lock bolt is formed with a long major bar having two different formation angles and formation intervals on the surface of the rock bolt and a short bar. Has also been proposed (Patent Document 2).

JP-A-11-324595. JP 2001-214700 A.

  Any of the above-mentioned rock bolts can exhibit sufficient strength at the ground support stage and can be expected to adhere to the fixing material, but its performance is designed at the manufacturing stage, such as the shape of the node, the formation pitch, etc. It was decided by. Therefore, according to the natural ground condition at the site, after the construction of the lock bolt, until the strength of the fixing material is filled with the lock bolt until the fixing material is expressed, There has been a demand for the development of a rock bolt capable of sufficiently expressing the action and effect. Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and the present invention forms anchors of a predetermined shape at the intermediate position in the longitudinal direction of the lock bolt, and appropriately changes the shape and number thereof. By increasing the adhesion between each anchor of the lock bolt and the fixing material, the effect of the lock bolt at the early age of the fixing material is secured, and the range of ground conditions where the lock bolt can be applied is expanded. It is to provide a lock bolt that makes it possible.

  In order to achieve the above object, the present invention is characterized in that a node anchor is retrofitted at a predetermined interval in the longitudinal direction of the lock bolt body.

  At this time, it is preferable that the node anchor has a weight-like portion pointed toward the back of the hole into which the lock bolt main body is inserted, and is retrofitted to the lock bolt main body.

  Alternatively, it is preferable that the node anchor has a hook-like body and is retrofitted to the lock bolt body.

  Alternatively, it is preferable that the node anchor is formed by attaching a plurality of branch-like bodies bent so as to be pointed toward the inner side of the hole into which the lock bolt is inserted, and is formed later on the lock bolt body.

  As the fixing means, it is preferable that the node anchor is formed by direct pressure contact with a predetermined position on the peripheral surface of the lock bolt main body or by casting using a placed mold.

The node anchor preferably has an opening formed in a part of the anchor, and is fitted to the peripheral surface of the lock bolt main body through the opening so as to be engageable, and is fixed to the lock bolt main body.

  The node anchor is preferably provided with a nut-like cylindrical flange capable of screwing the anchor to the peripheral surface of the lock bolt main body, and is fixed by screwing to the lock bolt main body.

  The node anchor is preferably formed on a circumferential surface of a sleeve joint to which the end of the lock bolt can be connected, and the node anchor is disposed by connecting a plurality of short lock bolts by the sleeve joint.

  In order to reliably fill the fixing material, it is preferable that the fixing anchor passage part is formed in a part of the node anchor.

  Furthermore, it is preferable that an opening end of the fixing material supply means is disposed in the vicinity of the fixing material passage portion of each node anchor.

  According to the present invention, at a stage where tunnel excavation is in progress, it is possible to set rock bolt proof strength according to ground conditions by site design, and at the construction stage, the lock bolt body is formed at a predetermined interval. The joint anchor can sufficiently exert the effect of being able to sufficiently secure the pull-out strength of the lock bolt at an early stage until the strength of the fixing material is developed.

  Hereinafter, as the best mode for carrying out the lock bolt of the present invention, the following embodiments will be described with reference to the accompanying drawings.

  Each drawing in FIG. 1 is an explanatory view showing the construction stage of the lock bolt 10 according to the embodiment of the present invention shown in FIG. FIG. 2A shows a lock bolt in which a lock bolt main body 11 and node anchors 12 formed at a predetermined pitch by pressure welding are integrated with the lock bolt main body 11. The joint anchor 12 of the lock bolt 10 of the present embodiment is rolled and processed, and as shown in an enlarged view in FIG. 2 with respect to the lock bolt main body 11 made of a deformed steel bar, In order to reduce resistance when inserting the bolt hole back side, a sharp weight 13 is formed toward the hole deep side, and the rear end 14 (lock bolt hole base side) is a pull-out resistance when a lock bolt is applied. In order to increase this, it is finished in a cylindrical shape integrally formed from the weight-like portion 13. Further, in order to improve the filling property of the fixing material at the position of the node anchor 12 at the time of injection of the fixing material, as shown in FIG. 12 are formed in the longitudinal direction. As a method for attaching the node anchor 12, as a method that can be reliably externally fixed to the lock bolt body 11 having various surface shapes such as deformed steel bars, threaded steel bars, torsion steel bars, etc. The node anchor 12 member can be press-contacted, or the node anchor 12 can be cast as a cast iron member, and a mold can be placed at a predetermined position of the lock bolt body 11 with the lock bolt body 11 as a core. In the present embodiment shown in FIG. 1, a deformed steel bar having a total length of 4 m is used as the lock bolt main body 11 and the node anchors 12 are formed at three positions with a 1 m interval in the longitudinal direction. The node anchor 12 in the present example was set so that the outer peripheral diameter was 50 mm with respect to the anchor diameter (D25). Usually, the outer diameter of the node anchor 12 is preferably about 1.5 to 2 times the anchor diameter. A substantially cross-shaped slit 15 having a width of 10 mm was provided along the node anchor 12 (see FIG. 2B).

  Here, a modified example of the node anchor 12 will be described with reference to FIGS. FIG. 3 shows a lock bolt of a type in which a hook-like body 16 is attached to the lock bolt main body 11 as a modified example of the node anchor 12. This bowl-shaped body 16 is made of a steel plate processed plate having a disk shape supported on a cylindrical flange 17 that can be screwed onto a threaded steel bar on the inner surface. The cylindrical flange 17 can be screwed into the lock bolt main body 11 in a nut shape, and the hook-shaped anchor can be arranged at a predetermined position. A plurality of filler through holes are formed on the surface of the node anchor 12 of the rod-shaped body 16 so that the filling property of the fixing material 30 (see FIG. 1C) at the anchor position can be secured. In addition, although the diameter of this bowl-like body 16 is sufficiently smaller than the diameter of the rock drilling hole for rock bolts, it is preferable to set the bowl diameter on the back side of the hole to be small in consideration of workability during insertion. Moreover, it is also preferable to attach a sled-like auxiliary member (not shown) which is tapered toward the back of the hole as needed to enhance the insertion performance.

  FIG. 4 shows a modification of the node anchor 12 in which a plurality of branch bodies 18 bent into a substantially V shape are attached to a cylindrical support flange 17 similar to that shown in FIG. As shown in the figure, the node anchor 12 composed of a plurality of branch bodies 18 (four: see FIG. 5B) having a tapered shape sharpened toward the distal end side is formed in a nut shape on the screw bar steel. It is fixed to the lock bolt main body 11 through a support flange 17 that is screwed into the lock bolt body 11.

  Next, means for fixing the node anchor 12 to the lock bolt body 11 will be described with reference to FIGS.

  In FIG. 5, as an example of the attachment method, an opening in which an uneven shape that can be engaged with the uneven shape of the peripheral surface processing pattern of the lock bolt main body 11 is formed on the inner peripheral surface, and a part in the circumferential direction is cut off. A node anchor 12 is shown having a cross-sectional shape with In this attachment method, as shown in FIG. 6A, the opening 12a of the node anchor 12A is elastically deformed and spread using a fixing jig (not shown), and is moved to a predetermined position in the longitudinal direction of the lock bolt body 11. It should be installed so that it fits in. At this time, by engaging the concave and convex shape of the inner peripheral surface of the modified example of the joint anchor 12A and the concave and convex shape of the peripheral surface of the lock bolt main body 11, the joint anchor 12A and the lock bolt main body 11 are integrated, Sufficient strength in the longitudinal direction of the lock bolt body 11 can be secured. In addition, it becomes possible to send a filler to the whole rock bolt through the opening part 12a position. In addition, formation of the node anchor 12A by this attachment system is not limited to a steel lock bolt, and can also be applied to a fiber bolt. The fiber bolts are expected to be cut and the construction progressed according to the excavation, but in this case, with conventional fiber bolts, the fiber bolts that were cut and left in the ground are fixed. There are cases where the length is insufficient and the pulling strength cannot be secured. Even in that case, it is possible to sufficiently secure the pull-out strength of the fiber bolt that has been cut and shortened by attaching the node anchor 12A to the position in consideration of the construction stage by the attachment method or the like.

  6 shows a node anchor 12 having a screw structure similar to a known sleeve joint structure. As shown in the figure, for example, a lock bolt designed to have a total length of 4 m is connected using four unit lengths (for example, 1 m) of threaded bar steel, and as shown in FIG. A sleeve joint 12S serving as the node anchor 12 can be used. In the connection state shown in FIG. 6 (b), it is preferable that the fixing method of the connecting portion by the sleeve joint S is the same as that of a known sleeve joint structure. In addition, in FIG. 6, although the communication part (notch part) which can distribute | circulate to the lock bolt hole depth direction of a filler is not shown, it respond | corresponds by deleting the cross section of the node anchor 12 suitably as needed. Needless to say, you can.

  FIG. 7 shows a modification of the nut-shaped node anchor 12N. As shown in the figure, the node anchor 12N can be formed at a predetermined position of the lock bolt main body 11 by forming a nut shape that can be screwed into the threaded steel bar. As a method for fixing the nut, known fixing means such as an adhesive, a set screw (not shown), and a double nut structure can be appropriately employed.

  As described above, the node anchors 12 of various shapes can be fixed to the lock bolt body by appropriately selecting the fixing method. For this reason, the lock bolt which has the design flexibility of being able to comprise the node anchor of a some shape and a fixed pattern according to the condition of the field can be provided.

  Hereinafter, the construction procedure of the lock bolt having the node anchor 12 shown in FIG. 1 (a) will be briefly described with reference to FIG. As for the method of filling the fixing material 30, a pre-injection method is possible as in the case of the known construction of the lock bolt. As the fixing material used, when importance is attached to fluidity, ordinary cement mortar and cement bentonite to which a fluidizing agent is added are preferable, and silica resin and the like that can easily adjust the gel time can be used depending on the state of spring water. Moreover, when sufficient gel time can be taken, the premix mortar and cement bentonite which were coagulated with the coagulation accelerator are preferred. When rapid hardening is required, it is preferable to use a fixing material to which a rapid hardening additive is added in consideration of required curing timing.

  In the case of post-injection, it is also preferable to machine an injection hole in the lock bolt body 11, and in that case, it is preferable to appropriately design the tip opening, intermediate position opening, and the like. In general, as shown in FIG. 1B, it is preferable to pipe an injection hose (pipe) 20 along the lock bolt main body 11 and perform injection from the mouth of the lock bolt hole.

  In addition, a plurality of injection hoses 20 are piped along the lock bolt main body for each node anchor 12 and the tip opening of each pipe is arranged in the vicinity of the hole depth side of the node anchor so that each node anchor 12 It is also preferable that the fixing material can be reliably filled at the position.

  FIG. 1C shows a state where the lock bolt of the present invention is inserted into the lock bolt hole and the fixing material 30 is completely filled, and the bolt is fixed on the mouth side via the anchor plate 31 and the nut 32. Shows the state. As described above, the node anchor 12 of the present invention functions as a large tensile resistance member with respect to the fixing material 30 and increases the pull-out strength of the lock bolt at an early stage after the construction of the lock bolt until the strength of the fixing material is developed. Therefore, it is possible to fully express the effect.

Explanatory drawing which showed the structure and construction state of the rock bolt of this invention. The perspective view which showed the shape of the node anchor of the lock bolt shown in FIG. 1, and bolt sectional drawing. The perspective view which showed the modification of the node anchor of a lock bolt. The perspective view which showed the other modification of the node anchor of the lock bolt, and a bolt sectional view. Explanatory drawing which showed the attachment method to the bolt body of a node anchor (attachment method). Explanatory drawing which showed the attachment method to the bolt body of a node anchor (sleeve joint method). Explanatory drawing which showed the attachment method to the bolt body of a node anchor (nut method).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Lock bolt 11 Lock bolt main body 12,12A, 12S, 12N Node anchor 15 Slit 16 Saddle-like body 17 Support flange 18 Branch-like body 30 Fixing material

Claims (10)

  A lock bolt, wherein a node anchor is retrofitted at a predetermined interval in the longitudinal direction of the lock bolt body.   2. The lock bolt according to claim 1, wherein the node anchor has a weight-like portion that is pointed toward the inner side of the hole into which the lock bolt main body is inserted, and is retrofitted to the lock bolt main body.   The lock bolt according to claim 1, wherein the node anchor has a hook-like body and is retrofitted to the lock bolt main body.   2. The node anchor according to claim 1, wherein the node anchor has a plurality of branches that are bent so as to be pointed toward the inner side of the hole into which the lock bolt is inserted, and is retrofitted to the lock bolt main body. Rock bolt.   5. The lock bolt according to claim 1, wherein the node anchor is formed by direct contact with a predetermined position on the peripheral surface of the lock bolt main body or by casting using a mold that is disposed.   The node anchor has an opening formed in a part of the anchor, and is fitted to the peripheral surface of the lock bolt body through the opening to be fixed to the lock bolt body. The lock bolt according to claim 1.   The said node anchor is provided with a nut-shaped cylindrical flange capable of screwing the anchor to the peripheral surface of the lock bolt main body, and is screwed and fixed to the lock bolt main body. Item 5. The lock bolt according to item 4.   The node anchor is formed on a sleeve joint peripheral surface to which the lock bolt end can be connected, and the node anchor is arranged by connecting a plurality of short lock bolts by the sleeve joint. The lock bolt according to any one of claims 1 to 4.   The lock bolt according to any one of claims 1 to 8, wherein the joint anchor has a fixing material passage part formed in a part thereof.   The lock bolt according to any one of claims 1 to 9, wherein the node anchor has an opening end of a fixing material supply means disposed in the vicinity of a fixing material passage portion of each node anchor.

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