JP6351280B2 - Rock bolt construction method - Google Patents

Description

  The present invention relates to excavation earth retaining work for civil engineering work, temporary earth retaining work during excavation, reinforcement earth work method using rock bolts used for strengthening against rainwater and earthquakes on slopes and reinforcing structures, and for cores when pulling out casings, etc. The present invention relates to a lock bolt construction method in which the co-up of the materials hardly occurs, the centering is easy, and the core material can be firmly fixed.

  The fixing of the core material in the conventional rock bolt construction method, especially in the case of the rock bolt construction in the tunnel construction by the NATM construction method, the mortar droops when the upward lock bolt is inserted, and the vicinity of the lock bolt tip becomes unfixed. Cases have been pointed out.

  In order to solve this problem, in Patent Document 1, a disk-shaped hardened material support valve having an outer diameter substantially equivalent to the diameter of the lock bolt hole is attached in advance to the outer periphery of the lock bolt, and the lock bolt is inserted into the lock bolt hole. When going, a method is used in which a hardening material such as a mortar is pushed up by a leg of the hardening material support valve or the like to suppress the formation of a gap at the tip of the lock bolt hole.

  In addition, if a part of the tip is replaced with a pack filled with a hardener, such as a mortar pack, and a method of breaking through the pack by inserting a lock bolt, the state of filling of the hardener at the tip of the lock bolt hole is more reliable. (See paragraph “0012”).

JP 2001-349196 A

  However, in the method using the push-up metal fitting, which is the tip fixing method of the core material according to the prior art document, there is an obstacle in the hole due to insufficient centering accuracy of the core material or partial collapse in the hole. If the push-up bracket is not fully opened, the thickness of the grout part covering the core material may become uneven, which may cause the core material to corrode due to insufficient coating, or the gap at the tip of the core material May remain unfixed and the effect of the lock bolt may not be fully exhibited.

  In particular, in the prior art document, an experiment for confirming the effect of the invention is described from paragraph number “0054” to paragraph number “0063”. In this experiment, the target rock is high-strength granite and the pore wall is very smooth. It is described that there was. However, in the ground where it is difficult to maintain the hole wall at the time of drilling, such as gravel ground, it is considered that the tip is not sufficiently fixed.

  Further, in the prior art documents, a part of the tip is replaced with a pack filled with a hardener such as a mortar pack, and the core tip is fixed by a method of breaking through the pack by inserting a lock bolt. Since it is impossible to collect the pack existing in the case, the torn pack remains at the tip of the core material and the mortar may be insufficiently filled.

  Therefore, in the present invention, even when it is difficult to ensure the shape of the hole wall due to gravel ground, etc., it is easy to ensure the centering accuracy of the core material, there is no corrosion of the core material tip, and the core material is firmly fixed. It is an object to provide a rock bolt construction method that can be performed.

The present invention provides a rock bolt construction method in which a ground is drilled, a core material is inserted into the drilled hole and a grout material is injected, and the core material is fixed in a support ground by curing the grout material. The pointed end of the core material is fixed to the supporting ground by being inserted into the hole bottom of the drilling hole by 5 cm to 20 cm via a core material pushing jig .

  This invention drills the ground, injects the grout material into the casing in the bore and inserts the core material, then pulls out the casing, and fixes the core material in the support ground by hardening the grout material. In the rock bolt construction method, the core material is inserted into the casing while the position of the shaft core is regulated by a spacer protruding from the outer periphery of the core material, and the pointed tip of the core material is inserted into the casing. It protrudes from the front-end | tip of this, It stabs in the hole bottom of the said drilling hole, It fixes to the said support ground.

  The core material according to the present invention is characterized in that the core material is pushed into the casing via a core material pushing jig provided with a core material guide portion. The spacer according to the present invention is adjacent to an annular support portion having a sliding surface on the outer peripheral edge, a base tube portion having a stopper member insertion hole, and a plurality of connecting members that connect the both portions. And a passage space provided between the connecting members. The sliding surface of the present invention is characterized by being an arcuate surface or a tapered surface.

  The present invention is configured as described above, and the tip of the core material (lock bolt main body) is inserted into and fixed to the hole bottom of the drilling hole, so that the drilling hole and the lock bolt main body are centered. Therefore, since the thickness of the grout material covering the lock bolt body can be made uniform, corrosion of the core material can be prevented.

  When a casing is used, the tip of the lock bolt body is inserted into the bottom of the hole and fixed to the supporting ground before the casing is pulled out, so that the center of the lock bolt body can be easily and accurately performed. You can also prevent time rise. Therefore, the efficiency and accuracy of the rock bolt construction can be ensured at the same time.

FIG. 2 is a view showing a first embodiment of the present invention and a front view showing a lock bolt body. It is a front enlarged view of the front-end | tip part of the lock bolt main body which concerns on this invention. It is a side enlarged view of the front-end | tip part of the lock bolt main body which concerns on this invention. It is a front view of the core material pushing jig | tool which concerns on this invention, and is a figure which shows the case where the core material guide part of a pushing guide member is bowl shape. It is a front view of the core material pushing jig | tool which concerns on this invention, and is a figure which shows the case where the core material guide part of a pushing guide member is cylindrical. It is a front view of the core material pushing jig | tool which concerns on this invention, and is a figure which shows the case where the core material guide part of a pushing guide member is circular arc shape. It is a construction procedure figure of the rock bolt construction method concerning the present invention, and is a figure showing a preparation (hole drilling machine installation) process. It is a construction procedure figure of the rock bolt construction method concerning the present invention, and is a figure showing a drilling process. It is a construction procedure figure of the rock bolt construction method concerning the present invention, and is a figure showing completion of drilling. It is a construction procedure figure of the rock bolt construction method concerning the present invention, and is a figure showing a cleaning process in a hole. It is a construction procedure figure of the rock bolt construction method concerning the present invention, and is a figure showing a primary injection process. It is a construction procedure figure of the lock bolt construction method concerning the present invention, and is a figure showing a pushing process by a core material insertion and core material pushing jig. It is a construction procedure figure of the rock bolt construction method concerning the present invention, and is a figure showing secondary injection and a casing extraction process. It is a construction procedure figure of the rock bolt construction method concerning the present invention, and is a figure showing a curing process. It is a construction procedure figure of the rock bolt construction method concerning the present invention, and is a figure showing a head fixing process. It is a principal part enlarged view of FIG. 5F. It is a figure which shows 2nd Example of this invention, and is sectional drawing which shows a part of rock bolt main body with which the casing was mounted | worn. It is a front view of a spacer. It is the IX-IX sectional view taken on the line of FIG. FIG. 10 is a sectional view taken along line XX in FIG. 9. It is sectional drawing of the coupler which has connected the core material.

  A standard example (first embodiment) of the rock bolt construction method of the present invention will be described with reference to FIGS. In this example, the centering / tip protection member (tip portion) 5 which is the tip portion of the lock bolt main body 1 is formed in a cone shape (pointed shape) having four bits 6 as shown in FIGS. As shown, the cone shape including the tip bit has an outer diameter Lc of 100 mm, and the cone itself has a diameter Ld of 60 mm. Although the general shape depends on the hardness of the ground, the diameter Ld is about 30 mm to 80 mm. Further, the bit 6 is not necessarily an indispensable condition depending on the ground properties, the construction purpose, and the like.

  The material of the tip cone portion 5a may be a material having corrosion resistance since the tip cone portion 5a is in direct contact with the ground, for example, a non-metallic member having strength and economy. Specifically, casting, hard resin, stainless steel, etc. are mentioned.

  As the operation of the centering / tip protection member (tip portion) 5 of the present invention, in the conventional construction method, the portion extending from the spacer 3a closest to the tip to the tip becomes a free end, and the centering accuracy of the lock bolt body 1 is improved. Since it is difficult to secure, as shown in FIG. 6, the tip structure of the centering / tip protection member 5 of the present invention is fixed by penetrating into the supporting ground 10 through the hole bottom 9a, and the free end state is released. Therefore, the centering accuracy can be ensured.

  As a result, when the casing 11 is pulled out, the tip cone portion 5a of the lock bolt body 1 is completely fixed to the support ground 10, and the core material 1c is located at the approximate center of the hole 9. Therefore, when the casing 11 is pulled out, the casing 11 And the lock bolt body 1 can be prevented from rising together. Furthermore, a mortar covering portion (cover) 13 is uniformly formed around the lock bolt main body 1 so that the lock bolt main body 1 can be fixed to the support ground 10 and protected from corrosion or the like.

  Next, the rock bolt construction method of the present invention will be described. The point of construction is in the method of placing the tip cone portion 5a of the lock bolt main body 1 on the support ground. In the ground piercing construction, it is necessary to pierce the tip cone portion 5a of the lock bolt main body 1 to the support ground 10 by hitting, and the tip cone portion 5a is surely bitten into the support ground 10 using a percussion method. The piercing length can be managed with the extra length.

"Drilling machine installation process" (see Fig. 5A)
For drilling, a skid-type or crawler-type rotary percussion drilling machine P is mainly used, and a work scaffold is installed in advance at a predetermined planned height. About a setting angle, an angle meter (slant) is used and it sets to a predetermined angle. When the total length of the core material (designed core material length) is long (3 m or more), the core material 1c is connected via the coupler 16, and the lock bolt body 1 is lengthened. In addition, a side groove 17 for wastewater treatment is provided on the butt, and a wastewater treatment is performed by providing a pot place at a position that does not interfere with excavation work as much as possible.

“Drilling process” (see FIG. 5B and FIG. 5C)
The drilling operation is performed by a single tube drilling method or a double tube drilling method by the rotary percussion drilling machine P. 5B and 5C show a situation of a double pipe drilling method using a casing. The inner rod 12 is inserted into the casing rod 11 so that the inner bit 12a attached to the tip of the inner rod 12 protrudes slightly from the tip of the casing rod 11, and the inner bit 12a and the ring bit 11a at the tip of the casing rod 11 cooperate. The support ground 10 is drilled. A drilling hole is attached to a casing rod (also referred to as “casing”) 11 having a predetermined diameter, for example, a diameter of 165 mm and a length of 1.50 m / piece, with a bit of φ170 mm, and percussion (rotation) + rotation (rotation) and thrust While giving, drill to a predetermined depth.

  As a rule, clean water is used for drilling, and bentonite and clay mixed solutions that adversely affect the frictional resistance between the fixing material and the ground are not used. The drilling length is managed by the number of casing rods used and the remaining scale.

“In-hole cleaning process” (see FIG. 5D)
When circulating water is used at the time when the drilling is completed to a predetermined length, the water is switched to fresh water, and the washing water is injected into the water supply pipe 15 to wash the slime and the like in the casing 11.

"Core processing process"
The core material 1c is trimmed to a predetermined length, and a spacer 3 is attached in advance to a predetermined position such as near the core material head. Carry-in materials and processed core materials are cured and stored with sheets.

“Primary injection process” (see FIG. 5E)
The injection hose 19 is inserted up to the hole bottom 9a of the casing 11, and the cement milk M remaining in the casing 11 and the cement milk M while being discharged from the injection hose 19 with a grout pump (not shown) of the predetermined blended cement milk M. And replace. The filling / replacement operation is completed when it is confirmed that the cement milk M (also referred to as grout material) flows out of the casing hole port 11c and the cement milk M is completely replaced with the drilling water W. Thereafter, the processed core material 1c is slowly inserted by human power while being connected by the coupler 16.

“Core material insertion / push-in process with special jig”
After the insertion of the lock bolt main body 1 is completed, the core material pushing jig 20 attached to the extension rod is inserted into the casing 11, and the core material 1 c is pushed through the core material pushing jig 20. The tip cone portion 5a is projected from the tip of the casing 11 and pierced into the supporting ground 10 to be fixed. The required insertion depth of the tip cone portion 5a for fixing into the support ground 10 is about 5 cm to 20 cm, although it depends on the properties of the ground.

“Secondary injection and casing drawing process” (see FIG. 5G)
Thereafter, the casing 11 is sequentially pulled out and collected from the hole 9, and in parallel with the drawing and collecting operation of the casing 11, secondary (filling) injection is performed. The lock bolt main body 1 is covered with mortar (grouting material), concentric with the hole 9 and fixed to the support ground 10.

  The core material pushing jig 20 will be described in more detail. 4A to 4C are front views of the core material pushing jig 20. The core material pushing jig 20 inserted in the casing 11 is a core material pushing force that transmits the pushing force from the hammer mechanism portion of the rotary percussion drilling machine P (not shown) to the core material 1c via the core material pressing surface 22. It consists of a transmission member 24 and a core material pushing guide member 26 that transmits the pushing force to the core material 1c.

  The core material pushing jig 20 is provided so as to be able to contact and separate from the core material 1c, and is not connected to the core material 1c. This core pressing jig 20 transmits the pressing force from the hammer mechanism of the rotary percussion drilling machine P to the core 1c. And since the tip cone portion 5a of the core material 1c is stuck and fixed to the support ground 10, the core material pushing jig 20 is removed from the core material 1c and taken out from the casing 11, so that the casing pulling process in the next step is performed. Can be easily done.

  The core material pushing guide member 26 is formed so that the pushing force from the hammer mechanism of the rotary percussion drilling machine P can be reliably transmitted to the core material 1c even if the position of the core material 1c is somewhat decentered. Thus, there is an effect of preventing the pushing motion of the core material 1c when the pushing force is transmitted.

  The core material pushing guide member 26 has an effect of preventing the pushing motion of the core material 1c when the pushing force is transmitted, and abuts the hammer mechanism portion of the rotary percussion drilling machine P and the core material 1c without being fixed. The shape is not limited as long as it is separated without resistance when the casing is pulled out.

  The core material pushing jig 20 having the shape and function has two purposes.

  The first object is that when the pushing force from the hammer mechanism of the rotary percussion drilling machine P is transmitted to the core pushing guide member 26, the center position (axial core) of the core 1c is the position of the hammer mechanism. Even if the center position (axial core) is misaligned, the core material pushing guide portion 26a of the core material pushing guide member 26 is not fixed, so that the core material center position substantially coincides with the center position of the hammer mechanism portion. This is because the force and moment perpendicular to the axial direction are not transmitted to the core material 1c, and only the pushing force in the axial direction is reliably transmitted to the core material 1c.

  The second purpose is to prevent the core material 1c from getting out of the way in the casing drawing process. As a specific example, in FIG. 4A, the core material pushing guide member 26 has a flange portion 28 having a slightly smaller diameter than the casing 11, and the core material pushing guide portion 26 a is provided on the flange portion 28. The core material pushing guide portion 26a is a hollow portion shaped so as to wrap the core material 1c at the center of the front surface of the flange portion 28.

  4B, the core material pushing guide member 26 has a flange portion 28 having a slightly smaller diameter than the casing 11, and the core material pushing guide portion 26a is provided on the flange portion 28. The core material pushing guide portion 26a is a cylindrical portion formed so as to surround the core material 1c at the center of the front surface of the flange portion 28. Further, in FIG. 4C, the core material pushing guide member 26 has a crescent shape portion 35, and the crescent shape portion 35 is provided with a core material pushing guide portion 26 a. The core material pushing guide portion 26 a is an arc-shaped portion formed on the front surface of the crescent shaped portion 35.

“Curing process” “Head fixing process” (see FIG. 5H and FIG. 5I)
After completion of the formation of the lock bolt, curing is performed for a predetermined period, and the core material head plate 30 is fixed with the lock nut 32.

  Next, a second embodiment of the present invention will be described with reference to FIGS. 7 to 11. The same reference numerals as those in FIGS. 1 to 6 have the same names and functions.

  Since this embodiment and the first embodiment are different in (1) spacer and (2) coupler, these points will be described below.

(1) About the spacer The spacer 3 inserted in the casing 11 has an annular support portion 43, a cylindrical base portion 45, one end connected to the support portion 43, and the other end connected to the cylindrical base portion 45. A connecting member 47 connected thereto. The outer diameter of the support portion 43 is formed slightly smaller than the inner diameter of the casing 11, and a sliding surface 43a is formed on the outer peripheral edge portion thereof. The sliding surface 43a is provided to reduce the resistance of the joint projection 11b on the inner surface of the casing 11 when the casing 11 is pulled out, and is provided on the tip protection member (tip portion) side of the lock bolt main body 1. Yes. An arcuate surface, a tapered surface, or the like is employed as the sliding surface 43a.

  The inner diameter of the through hole of the cylindrical base 45 is formed to be slightly larger than the outer diameter of the core material 1c, and the other end of the connecting member 47 is connected to the front end 45a, and the rear end 45b is fixed to the rear end 45b. A member insertion hole 45c is formed. A screw or the like as a stop member is inserted into the insertion hole 45c to fix the cylindrical base portion 45 to the core material 1c. The other end of the connecting member 47 can be fixed to the central portion of the cylindrical base portion 45 or the rear end portion 45b.

  A plurality of, for example, three connecting members 47 are provided at intervals in the circumferential direction. The width of the connecting member 47 is, for example, substantially equal to the thickness 43L of the support portion 43, but the width, shape, and the like can be appropriately selected as necessary. Between the adjacent connecting members 47, a passage space 49 constituting a passage for cement milk is provided. The passage space 49 is formed to have a substantially uniform size, but the size and the like can be appropriately selected as necessary.

  In the case of performing the lock bolt construction, when attaching the spacer 3 to the core material in the core material processing step, the cylindrical base portion 45 of the spacer 3 is inserted into the core material 1c, and then a screw or the like is inserted into the fixing member insertion hole 45c. The spacer 3 can be easily fixed to the core material 1c by inserting and attaching the tip thereof to the outer peripheral surface of the core material 1c.

  Further, when the casing is pulled up in the casing drawing process, the outer edge portion of the annular support portion 43 of the spacer 3 of the lock bolt body 1 contacts the joint projection 11b on the inner surface of the casing 11, but the outer edge portion slips. Since the surface 43a is formed, the casing 11 can be pulled up without receiving a large resistance. Therefore, it is possible to prevent the lock bolt main body 1 from being lifted (co-raised) together with the casing 11.

(2) About Coupler The coupler 16 that connects the core material 1 c includes a cylindrical member 51, a core material screw hole 52 that penetrates the central portion of the cylindrical member 51, and a plurality of couplers provided on both ends of the cylindrical member 51. And a screw hole 53 of the bolt. Four screw holes 53 are formed in the radial direction of the cylindrical member 51.

  When performing the rock bolt construction, when connecting the core material in the primary injection process, the end portion 1d of one core material 1c is screwed from one end side of the core material screw hole 52 of the coupler 16, and the end portion 1d is inserted to the center of the core material screw hole 52. Next, the end portion 1e of the other core member 1c is screwed from the other end side of the core member screw hole 52 of the coupler 16, and the end portion 1e is brought into contact with the end portion 1d of the one core member.

  Thereafter, a bolt 55 is screwed into each screw hole 53, and the tip of the bolt 55 is fastened to the outer peripheral surface of the core material 1c and fixed, whereby both the core materials 1c and 1c are firmly connected via the coupler 16. And become one.

1 Lock bolt body 1c Core material 3 Spacer 5 Centering / tip protection member (tip)
9 Drilling hole 9a Hole bottom 10 Support ground 11 Casing 20 Core material pushing jig 24 Pushing transmission member 26 Pushing guide member 26a Core material guide part

Claims (5)

In the rock bolt construction method in which the ground is drilled, the core material is inserted into the drilled hole and the grout material is injected, and the core material is fixed in the support ground by curing the grout material.
A rock bolt construction method characterized in that a pointed tip of the core material is inserted into a hole bottom of the drilling hole via a core material pushing jig and is fixed to the support ground by 5 cm to 20 cm . Drilling the ground, injecting the grout material into the casing in the borehole and inserting the core material, then pulling out the casing and fixing the core material in the support ground by hardening the grout material In the method
The core material is inserted into the casing with the axial core position regulated by a spacer protruding from the outer periphery of the core material,
A rock bolt construction method, wherein a pointed tip portion of the core member is projected from the tip of the casing, inserted into the hole bottom of the drilling hole, and fixed to the support ground.   The lock bolt construction method according to claim 2, wherein the core material is pushed into the casing through a core material pushing jig provided with a core material guide portion. The spacer includes an annular support portion having a sliding surface on an outer peripheral edge portion, a base tube portion having a stopper member insertion hole, and a plurality of connecting members that connect the support portion and the base tube portion. The rock bolt construction method according to claim 2, further comprising: a passage space provided between adjacent connecting members.   The rock bolt construction method according to claim 4, wherein the sliding surface is an arcuate surface or a tapered surface.

Images