JP2012057328A - Method of constructing short-length rock bolt by 2-way pressure injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method of a rock bolt by a 2-way pressure injection system, capable of surely realizing secured filling confirmation of a solidification material not generating air accumulation and pressure injection thereafter in a well balanced manner over the entire length of a short-length bolt.SOLUTION: In order to close a plurality of injection lateral holes (a) provided near the mouth of a drilling rod 1, a collared sleeve 5 is fitted into the drilling rod 1 and drilling is performed. The solidification material E is injected from a rod center hole leaving the sleeve 5 inside the drilling rod 1, and after confirming the return of the solidification material E from an air relief hose 8, the air relief hose 8 is bent and closed. The primary pressure injection of the solidification material E is positively performed from a bit side to the peripheral natural ground F. Thereafter, the sleeve 5 is pulled out to open the injection lateral holes (a) to a drilling hole, the solidification material E is pressure-injected again from the rod center hole, and the secondary pressure injection is performed positively again from the injection lateral holes (a) to the peripheral natural ground F.

Description

  This invention is a lightweight boring machine especially for access and narrow area construction restrictions, such as ground reinforcement work, slope reinforcement work, repair work for filling the back cavity of the existing slope and reinforcement of the slope surface layer. (Short width of 2m or less) and short rock bolts of less than 2.5m in length that can only be constructed manually using leg drill machines under extremely severe construction conditions where small rock drills such as crane drills cannot be carried in. In the construction, a drilling rod with a hollow structure and a male thread formed on the outer surface is used for a ground where the drilling wall is not self-supporting and difficult to dig a single pipe. The present invention relates to a construction method of a two-way pressure injection type short rock bolt constructed by pressure-injecting a solidified material from two directions on the vicinity side.

[Background technology-1]
Figures 5 and 6 are often used for slope reinforcement work, underpeening of existing foundations, foot reinforcement in tunnel excavation, and other reinforced earth work in grounds where the ground conditions are poor and the borehole wall is not self-supporting. The construction method of the rock bolt by the conventional partial double pipe system is shown.

  First, as shown in FIG. 5, the diameter of the hollow rod 21 is slightly larger than that of the short tip conduit 22 that is simultaneously placed with the drilling rod 21 at the tip of the drilling rod 21 having a hollow structure and an outer surface that is well coupled with the solidified material. The drilling lost bit 23 is screw-connected, the tip of the short tip conduit 22 is opened at a slight distance from the drilling lost bit 23, and a short length is formed at or near the opening of the short tip conduit 22. For the purpose of centering with the drilling rod 21 that passes through the inner surface of the leading conduit 22, the short leading conduit 22 and its center are arranged in a state in which a center riser 24 having a plurality of independent plates or independent projections extending in the circumferential direction is arranged. The inner drilling rod 21 is drilled to a depth corresponding to the length of the short tip conduit 22, and then only the drilling rod 21 is removed to the required length, and the solidified material 25 is removed from the drilling rod 21. Lost tip through inner hole When the solidified material 25 reaches the base of the short tip conduit 22 from the hole 26, it is confirmed that the return valve 30 has overflowed. In a state where the return valve 30 at the mouth portion of the hole rod 21 and the short tip conduit 22 is closed, a predetermined amount of the solidified material 25 is further positively pressurized by the pressure P1 from the lost bit discharge port through the inner hole of the drilling rod 21. Injected to build rock bolts. (See Patent Document 1)

  Further, in FIG. 6, in order to realize balanced injection of the solidified material 25, a switching valve 28 is provided in the middle of the hose 27 that connects the mouth portion of the drilling rod 21 and the mouth portion of the short tip conduit 22. By connecting the solidifying material supply source through the switching valve 28, the "positively pressurized injection" of the solidifying material 25 into the inner hole of the drilling rod 21 and the short tip conduit 22 is performed by switching the valve 28. For the drilled portion that has been pursued only by the drill rod 21 and the lost bit 23, the “two-way pressurization” from the distal end side (pressure P1) of the short end conduit 22 and the discharge port side (pressure P2) of the lost bit 23 is applied. By performing “pressure injection”, further ideal pressure injection is realized.

  The hole-drilling rod 21 can achieve its purpose as long as it has a hollow structure and has an outer surface with good adhesion and bonding with the solidified material. In particular, a self-drilling bolt having a hollow structure and a continuous rolling screw formed on the outer surface is used. This drilling rod 21 can be connected to the required length by a coupler 29, and the short tip conduit 22 is made of STKM13A steel pipe having a length of 1.5 m to 2 m, an outer diameter of φ63.5 mm, and a thickness of 5 mm. In this case, the outer diameter of the lost bit 23 is φ65 mm.

[Background technology-2]
FIGS. 7 to 9 are improved techniques for grout injection of self-drilling bolts used in bad ground where self-drilling holes are not self-supporting. A grout outlet 34 communicating with the hollow portion 32 is opened on the peripheral surface of the self-drilling lock bolt 33 having the portion 32, and the outer diameter substantially coincides with the inner diameter of the hollow portion 32 as shown in FIG. The flexible hose 35 is inserted to close the outflow port 34. In this state, the high-pressure fluid is injected to forcibly discharge rock powder and earth and sand powder, and after completion of drilling, the flexible hose 35 is removed from the hollow portion. A grout method for self-drilling bolts, which consists of injecting grout material around the lock bolt 33 through the drill head 31 and the grout outlet 34, has been introduced. (See Patent Document 2)

  In the means for solving the problem of the background art-2, the drill head 31 is attached to the tip, and the hollow portion 32 is connected to the peripheral surface of the self-drilling lock bolt 33 having the hollow portion 32 serving as a high-pressure fluid inflow hole. The grout outlet 34 to be opened is opened at a necessary interval, and at the time of drilling, a flexible hose 35 having an outer diameter substantially coinciding with the inner diameter of the hollow portion 32 is inserted to close the outlet 34. And the rock hose 35 is forcibly discharged, and after completion of drilling, the flexible hose 35 is removed, and the grout is injected around the lock bolt 33 from the hollow portion 32 through the drill head 31 and the extraction port. Explained.

  In the embodiment in Patent Document 2, the lock bolt 33 is rotated at the time of drilling and drilled by the drill head 31, and when it is long, it is drilled by a coupling nut. After drilling a predetermined length, it is flexible to a position where the outlet is closed. With the flexible hose 35 inserted, a high-pressure fluid is injected from the flexible hose 35 to forcibly remove rock powder and earth and sand powder, and then the flexible hose 35 is removed and the grout is injected from the hollow portion. ing.

  Here, Patent Document 2 discloses that the means for solving the problem is that a hole is drilled in a state in which a flexible hose having an outer diameter that substantially matches the inner diameter of the injection hole is inserted during drilling. If the tube is long, it is drilled with a coupling nut, and after drilling for a predetermined length, the tube is inserted after the tube to the position where the outlet is blocked. There is a contradiction.

  In Patent Document 2, there is no pressure loss due to the tube, rock powder and earth and sand powder are excluded, and the grout is injected into a relatively uniform region over the entire length of the hole by the outlet, and the effect is that the grout is the entire length of the perforated part. The rock bolts can be firmly fixed, and the forced discharge of rock powder and earth and sand powder is performed smoothly without loss of pressure. Therefore, it is extremely advantageous especially for long drilling and collapsible geology. There is.

JP 2007-107372 A Japanese Patent Publication No. 5-60040

Problems with Patent Document 1 By the way, the construction of the rock bolt according to Patent Document 1 described above is a “partial double tube method” that requires a double tube drilling at the mouth with a short tip conduit, and is a lightweight boring. Only manpower construction using leg drill machines that are constructed with the operator hanging on a rope under extremely severe construction conditions that can not carry in a small rock drill such as a machine (scaffolding width 2m or less) or a crane-type drill. Rock bolt drilling in the field where it was impossible was difficult.

  In addition, the outer diameter of the tip conduit selected according to the outer diameter of the self-drilling bolt used for the drilling rod is about φ63.5 mm, and the lost bit for drilling has a slightly larger diameter than the short tip conduit placed simultaneously. The diameter is relatively large (φ65 mm), and a construction method with a smaller drilling diameter has been awaited at a site where only manual construction using a leg drill is possible.

  Furthermore, the dedicated swivel and the short end pipe are expensive consumable members, and the lost bit is relatively expensive. Therefore, a small-diameter size is desirable, and a further economical construction method has been expected.

Issues regarding Patent Document 2 Regarding “Background Technology-2”, which employs a small-diameter lost bit and provides an outlet on the side surface of the self-drilling bolt to improve the injectability, not only the hole drilling means but also the injection process However, there has been a demand for providing a construction procedure including confirmation of grout filling without causing air accumulation in the perforation and a subsequent pressure injection process.

  In particular, it is not preferable to remove the tube after drilling and batch-inject it from the hollow part of the bolt, because the air in the drilling cannot be discharged and the grout is filled randomly from multiple outlets. It was necessary to establish a process of filling and then pressurizing firmly.

  Also, when drilling while connecting with a coupling nut with a long bolt, depending on the position of the outlet, it is necessary to replace the long tube for each connection in order to extend the tube to be inserted. In addition, if the long drilling hole is set to the “post-insertion method” without placing the tube, there is a possibility that rock or earth and sand dust will enter the hollow part of the bolt from the bolt inlet during drilling and the tube cannot be inserted afterwards. was there.

  Therefore, the problem of the present invention is that, in contrast to Patent Document 1, in the unstable ground of the drilling wall, such as a lightweight boring machine (scaffolding width of 2 m or less) or a crane type drill due to restrictions on access and narrow land construction. It is limited to the construction of short rock bolts with a length of less than 2.5m for human construction using leg drill machines that are constructed with the operator hanging on the rope under extremely severe construction conditions where a small rock drill cannot be carried in. Thus, there is provided an economical and easy manual construction method for a lock bolt that does not require an expensive consumable member such as a dedicated swivel or a short tip conduit, and requires only a small lost bit diameter.

  In addition, with respect to Patent Document 2, “two-way pressurization” can be realized in a well-balanced and reliable manner over the entire length of a short bolt less than 2.5 m in length, by confirming filling of solidified material without causing air accumulation and subsequent pressurization and injection. The construction method of the rock bolt by "injection system" is provided.

  In order to solve the problems as described above, the present invention is arranged such that a plurality of injection lateral holes are arranged in the vicinity of the mouth of the drilling rod, and drilling water sent from the injection lateral hole to the tip bit part through the bolt central hole at the time of drilling. Drilling is performed by inserting a short, hollow collared sleeve with a sealing rubber ring at the tip into the center hole of the drilling rod so that compressed air does not leak.

  When drilling is complete, place an air vent hose at the base of the drill rod, caulk the drill outlet on the outer periphery of the bolt with a padding material, and place a short, hollow collared sleeve in the center of the drill rod. The solidified material is injected from the center hole of the rod while remaining in the hole, and discharged from the tip bit part discharge port and the bit vicinity discharge port to securely fill the inside of the drilling hole, and the return of the solidified material from the air bleeding hose was confirmed. Later, the air bleeding hose is folded and closed, and further, the solidified material is injected under pressure from the “bit side”.

  After that, pull out the short hollow sleeve with collar to open a plurality of injection side holes near the drilling rod mouth to the drilling hole side, and pressurize and inject the solidified material again from the center hole of the drilling rod. The secondary pressure is injected into the surrounding natural ground from a plurality of injection lateral holes.

  By adopting the pressure injection method of the solidified material, the short lock bolt that is usually driven obliquely downward is first discharged from the lower end bit part discharge port and the bit vicinity discharge port, from the lower side Solidified material is filled so as to push air upward, the return can be confirmed from the exhaust hose at the mouth, and then reliable two-way pressure injection from the tip bit part side and then the injection side hole side near the mouth is performed. This can be realized and the solidified material can be press-fitted in a well-balanced borehole and surrounding ground.

  The above-mentioned drilling rod can achieve its purpose as long as it has a hollow structure and has an outer surface with good adhesion and bonding to the solidified material. In particular, a self-drilling bolt having a hollow structure and a continuous rolling screw formed on the outer surface is used. This drilling rod is connected to the required length by a coupler.

  Because of the structure that does not apply an excessive load or impact to the drilling rod or lost bit, use a self-drilling bolt with a plurality of horizontal holes for injection near the mouth of the drilling rod. Rotation and blow from the rock drill (leg drill machine) on the ground surface are transmitted to the lost bit for drilling at the tip, and at the same time, water or compressed air for removing slime (waste soil) is sent to the center hole of the self-drilling bolt Take measures to send more.

  The slime generated in the lost bit part was sent to the tip bit part without being discharged from a plurality of lateral holes through the inner hole of a short, hollow collar sleeve built in the center hole of the self-drilling bolt on the mouth side. It is scoured by water or compressed air, guided to the gap between the outer surface of the self-drilling bolt and the drilling hole, and discharged from the mouth drilling hole on the side of the rock drill (leg drill machine) to advance the drilling.

  The drilling of this technology is the construction of a leg drill machine with a rope scaffold used for manual drilling, a short lock bolt with a bolt length limited to 2.5 m or less at the maximum, and drilling due to the collapse of the mouth drilling wall The adverse effect on slime discharge is minor, and there is no blockage of drilling holes as occurs with long bolts.

  In addition, in the injection of this technology, solidified material is filled from the tip bit portion discharge port and the bit vicinity discharge port in a state where the lateral hole of the mouth portion is closed with a short hollow sleeve with a collar, and then the mouth portion is closed. Primary pressure injection in the state, and pulling out the sleeve with collar, the secondary pressure injection from a plurality of horizontal holes near the mouth is performed in order, and “two-way pressure injection” is performed in order to shorten the length of the pipe Realize without using lost bit and dedicated swivel.

  According to the present invention, in the construction of a short rock bolt having a length of 2.5 m or less using a leg drill machine, the solidification material is reliably filled in the drilling hole, and then pressure injection is performed from two directions. “Pressure injection type” self-drilling bolts can be realized, and it has been difficult to access with crane type drills and small boring machines (scaffolding width of 2m or less). It is possible to cope even with bad rock bolt construction.

  In addition, using the center hole of the self-drilling bolt and multiple injection lateral holes near the mouth, it is possible to realize a reliable single pipe digging hole, a well-balanced tip, and “two-way pressure injection” from the mouth. In addition, it is possible to improve the economy by eliminating the need for an expensive short tip conduit, a large-diameter lost bit, and a dedicated swivel, which were necessary in the past.

  Furthermore, since all the parts to be adopted are lighter and smaller than the self-drilling bolts, the material can be transported and transported easily during the construction of the rope scaffolding in the confined areas where access is poor.

Longitudinal side view showing a situation in the middle of placing a lock bolt by the method for constructing a lock bolt of the present invention (A) is an enlarged vertical side view showing a base end portion in the middle of setting of the lock bolt according to the method of constructing the lock bolt of the present invention, and (b) is a perspective view in which a sleeve with a collar and a steel split ring are divided. Longitudinal side view showing solidification material filling work of rock bolt by construction method of rock bolt of this invention Vertical side view showing a state in which the filling of the solidified material by the method for constructing the lock bolt of the present invention and the subsequent two-way pressure injection operation are completed Longitudinal side view showing a situation in the middle of placing the lock bolt by the partial double pipe method in the conventional construction method of the lock bolt of the first example Longitudinal side view showing a state in which the two-way pressure injection operation by the partial double pipe method is completed by the conventional construction method of the lock bolt of the first example Longitudinal side view showing the state of the horizontal hole arrangement of the lock bolt by the construction method of the lock bolt of the conventional second example A longitudinal side view showing a state in which the construction of the lock bolt by the construction method of the lock bolt of the second conventional example is completed. Enlarged longitudinal side view showing the relationship between the horizontal hole of the lock bolt and the tube to be inserted by the construction method of the lock bolt of the second conventional example

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

  The construction method of the rock bolt according to the present invention is performed using the short drilling rod 1. The short drilling rod 1 is used by connecting one or more in accordance with the conditions of the construction site.

  1 to 4 show a construction method of a lock bolt when two short drilling rods 1 are used, and two short drilling rods 1 and a coupler 2 that connects the short drilling rods 1. , Screwed to the tip of the tip side short drilling rod 1a and screwed to the rear end of the drilling lost bit 3 having a diameter slightly larger than the outer diameter of the drilling rod 1 and the rear end side short drilling rod 1b. Leg adapter 4 for connecting to a leg drill machine (rock drill) installed by connection, short hollow collar collar 5 to be inserted into the rear end short drill rod 1b, A rubber cone 7 for sealing between the hole 6 by the lost bit 3 for hole and the vicinity of the rear end side short hole rod 1b, an exhaust hose 8 for extracting air from the hole 6, and a solidified material E Realized reliable filling and pressure injection into the drilling hole 6 Because of the special injection adapter 9 or the like is used.

  The short hole rod 1 has, for example, a length of about 1.0 m, the rod center hole 10 penetrates along the axis, and has an outer diameter φ32 mm that presents a continuous rolling screw on the outer surface, and the rod center hole 10. A self-drilling bolt having a diameter of φ17 mm is used.

  The drilling lost bit 3 attached to the tip of the tip side short drilling rod 1a has a discharge port b1 at the tip bit portion, and the tip side short drilling rod 1a is discharged in the vicinity of the drilling lost bit 3. An outlet b2 is provided, and a plurality of injection lateral holes a are provided near the mouth of the rear end side drilling rod 1b.

  The collar-equipped sleeve 5 has a length capable of closing the injection lateral hole a when inserted into the rod center hole 10 of the rear end side drilling rod 1b from the rear end side. A sealing rubber ring 5a is mounted at the front end and a collar 5b is provided at the rear end so that the drilling water and compressed air H do not leak outside.

  Next, the two-way pressure injection type short rock bolt construction method of the present invention will be described in the order of construction.

  FIG. 1 shows a state of drilling a rock bolt according to the present invention, in which a short drilling rod 1 having a length of 2.0 m is being driven by a manually drilled leg drill machine (rock drill). The installation of the short drilling rod 1a on the side is completed, and the additional rear end short drilling rod 1b is connected by the coupler 2 having an outer diameter of φ42 mm and a length of 120 mm.

  A leg adapter 4 for connecting to a leg drill machine is attached to the rear end side of the rear end side short drilling rod 1b by screw connection, and the tip bit portion discharge port of the lost bit 3 for drilling through the rod center hole 10 b1 and the sleeve 5 with a collar are provided in the center hole 10 of the rear end side short hole hole rod 1b so that the hole water or compressed air H sent to the discharge hole b2 near the bit does not leak to the outside from the plurality of injection holes a. The drill bit is advanced with the lost bit 3 having a hole diameter of 50 mm, and the excavated waste soil (slime) G passes through the hole 6 and is discharged from the mouth on the rear end side.

  FIG. 2 (a) shows details of the rear end side in the state of drilling work according to the present invention, and the rear end side of the rear end side short drilling rod 1b is connected to a leg drill machine (manpowered cutting) by way of a leg adapter 4. The rear end side short drilling rod 1b is provided with a dimensional position of approximately C from the rear end portion, and the injection lateral holes a having a diameter of 10 mm in a staggered manner of 90 degrees toward the rod tip are pitch B × 3. Arranged in rows (total φ10 mm x 6 holes), collar sleeve 5 with outer diameter φ15 mm, inner diameter φ9 mm, and length L is inserted from the inside of leg adapter 4 into drilling rod center hole 10. It is arranged so as to fit inside the steel two-parted ring 11 shown in 2 (b), and is in the final drilling operation.

  The length L of the sleeve 5 with the collar is L ≧ 2B + C + 50 mm in FIG. Here, B is the distance between the injection lateral holes a, and C is the distance from the rear injection lateral hole a to the rear end of the collared sleeve 5.

  FIG. 3 shows that the drilling operation of the present invention is completed, the leg adapter 4 on the rear end side and the steel two-split ring 11 are removed, and the sleeve 5 with the collar is left and the drilling rod 1 and the drilling hole 6 are removed. A tapered rubber cone 7 with an exhaust hose 8 disposed at the mouth is driven into the back about 5 cm from the mouth, and the mouth is mortared to prevent leakage of the solidified material E (here, cement paste) at the mouth during pressure injection. Is a state diagram in which a special injection adapter 9 is set on the rear end side of the drilling rod 1 in order to realize the reliable filling and pressurizing injection of the solidified material E into the drilling hole 6. is there.

  In FIG. 3, if injection is performed by setting the supply source of the solidification material E to the injection port 9 b of the special injection adapter 9, the solidification material E passes through the special injection adapter 9 and drills through the inner diameter hole of the collared sleeve 5. The hole 6 is filled through the rod center hole 10 of the rod 1 from the tip bit portion discharge port b1 and the bit vicinity discharge port b2, and is filled securely while pushing up the air in the hole 6 and overflows from the exhaust hose 8 at the mouth portion. D can be confirmed.

  As shown in FIG. 4, if the overflow D from the exhaust hose 8 is confirmed and the solidified material E is surely filled into the drilling hole 6, then the exhaust hose 8 is bent and closed, and the solidified material is injected from the inlet 9b. The pressure of P1 is applied to E and “primary pressurization injection” is performed on the surrounding natural ground F.

  Next, the pressure at the injection port 9b to the solidified material E is once released, the lid 9a of the special injection adapter 9 is removed, the collared sleeve 5 is pulled out, and a plurality of injection horizontal holes a in the vicinity of the mouth are made into the drilling holes 6. After opening and reattaching the lid 9a of the special injection adapter 9, the pressure of P2 is applied to the solidified material E from the injection port 9b again and "secondary pressure injection" is performed on the surrounding natural ground F.

  FIG. 4 shows a state diagram in which the “two-way pressure injection” by the primary pressure injection and the secondary pressure injection described above according to the present invention is completed.

  By drilling two 1m-long drilling rods 1 with a coupler 2 in the surrounding natural ground F where the hole wall is not self-supporting, with a small φ50mm diameter lost bit 3 screwed to the tip, A lock bolt having a total length of 2 m inserted into the drilling hole 6 is constructed, and after the solidified material E is securely filled so that air does not enter the drilling hole 6, the tip bit part discharge port b1 and the vicinity of the bit are discharged. Sequential pressure injection is performed from the outlet b2 side and a plurality of injection lateral hole a sides near the mouth, and by this “two-way pressure injection”, the solidified material E is press-fitted into the surrounding natural ground F in a well-balanced manner. A high-quality short rock bolt has been constructed in which the rod 1 and the ground are firmly fixed.

  In the short lock bolt constructed as described above, the special injection adapter 9 is removed from the rear end side short drilling rod 1b, the exhaust hose 8 is cut along the slope A, and then the end side short length bolt is removed. A washer is installed at the rear end protruding from the slope A of the drilling rod 1b, and the nut is screwed in until it comes into contact with the slope A, so that the end portion of the short lock bolt is processed.

DESCRIPTION OF SYMBOLS 1 Drilling rod 1a Front side short drilling rod 1b Rear end side short drilling rod 2 Coupler 3 Drilling lost bit 4 Leg adapter 5 Sleeve with collar 5a Sealing rubber ring 5b Collar 6 Drilling hole 7 Rubber cone 8 Exhaust hose 9 Special Injection adapter 9a Lid 9b Inlet 10 Rod center hole 11 Steel split ring 12 Coking process a Injection side hole b1 Tip bit part outlet b2 Bit outlet near E E Solidified material F Periphery ground A Slope D Return H Drilling hole Water and compressed air 21 Drilling rod 22 Short tip conduit 23 Drilling lost bit 24 Centrizer 25 Solidified material 26 Drilling hole 27 Hose 28 Switching valve 29 Coupler 30 Return valve 31 Drill head 32 Hollow part 33 Self-drilling lock bolt 34 Grout Outflow port 35 Flexible hose

Claims (1)

For drilling a hole having a diameter slightly larger than the outer diameter of the drilling rod (1) at the tip of the drilling rod (1) having a hollow structure through which the rod central hole (10) passes and having a male thread continuous with the outer surface. The lost bit (3) is screwed and drilled. When the drilling (6) is completed, the drilling rod (1) and the lost bit (3) are left in the ground and the drilling hole (6) In the method for constructing a short rock bolt in which the solidified material (E) is injected from the rod center hole (10) of the drilling rod (1) into
A plurality of injection lateral holes (a) are arranged in the vicinity of the mouth of the drilling rod (1), and at the time of drilling, the lost bit (3) for drilling at the tip from the injection lateral hole (a) through the rod central hole (10) A hollow collared sleeve (5) with a sealing rubber ring (5a) at the tip is inserted into the center hole of the rod of the drilling rod (1) so that the drilling water and compressed air (H) sent to the part of (10) is inserted and drilled,
When the drilling hole (6) is completed, an air vent hose (8) is arranged at the base of the drilling rod (1), and the outlet part of the drilling hole (6) on the outer periphery of the drilling rod (1) is formed with a filling material. Is caulked (12), and the solidified material (E) is injected from the rod center hole (10) while leaving the sleeve (5) in the rod center hole (10) of the hole drilling rod (1). The lost bit (3) or the discharge ports (b1) and (b2) provided in the vicinity thereof are discharged to fill the hole (6), and the solidified material (E) is returned from the air vent hose (8). After confirming (D), the air bleeding hose (8) is closed, and the solidified material (E) is injected under pressure from the side of the lost bit (3) for drilling into the surrounding ground (F),
Thereafter, the sleeve (5) is pulled out, and the rod center hole (10) and the hole (6) are electrically connected to each other by a plurality of injection lateral holes (a) provided in the vicinity of the mouth provided in the hole drilling rod (1). The solidified material (E) is again injected by pressure from the hole (10), and this is secondarily injected from the injection lateral hole (a) to the surrounding ground (F) near the mouth of the drilling rod (1). A two-way pressure injection type short rock bolt construction method.

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