JP3974090B2 - Long face bolt construction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a long-distance advance construction method (AGF method), a long length, which is frequently used in a place where the geological conditions of a natural ground to be excavated are poor, in a natural ground advanced reinforcement construction method applied when excavating a tunnel or an underground cavity. Of the face bolt method and the leg reinforcement method, it is related to the construction method of the long face bolt method that is placed in the direction of excavation and is installed for the purpose of suppressing the extrusion of the face and the collapse of the mirror part during excavation Is.
[0002]
[Prior art]
In conventional tunnel excavation, a short (about 3 to 4 m) hollow rock bolt is placed at a predetermined interval along the top face of the face with a low profile, and various solidification materials (for example, silica resin) are injected, The ground was called fore-polling.
[0003]
For the face, a short (about 3 to 4 m) carbon fiber reinforced resin (FRP) bolt is cast in the direction of digging for the purpose of self-supporting the mirror part, and then a solidified material is injected and called a face bolt. The previous ground was improved.
[0004]
In recent years, in place of this fore-pouring driving, as shown in FIGS. 16 and 17, long (for example, 12.5 m) long reinforcing steel pipes 8 and 9 are usually provided in an elevation angle range of about 120 ° along the top face of the face. Is placed with a small angle θ of 4 to 6 ° upward from the direction of excavation, and the long reinforcing steel pipes 8 and 9 are back-filled with cement-based or resin-based solidified material, 9 is used to infiltrate and solidify the surrounding natural ground through a plurality of horizontal holes provided in the longitudinal direction, and various derived methods are introduced and put into practical use as the long tip receiving method (AGF method).
[0005]
Further, the face bolt 1 in the long face bolt construction method for the purpose of self-supporting the mirror surface 13 to which the sprayed concrete is applied with a thickness of about 10 cm is also a long length having a length of about 12.5 m or twice as much as 25 m. The various reinforcement methods are used to place the reinforcement material in advance, and the solidified material is filled into the surrounding ground or the pressure infiltration injection method is adopted. Has been put to practical use.
[0006]
Furthermore, the outer circumference of the mirror surface for the purpose of preventing the leg subsidence due to the large loading load by the AGF method and the advance improvement of the partial ground of the steel support 50 standing up every 1 meter in the progress of the subsequent excavation From the lower end portion, various kinds of preceding ground improvement (not shown) are carried out in a slanting front downward direction (for example, from 12 to 13 m) (not shown), which is called a leg reinforcement method.
[0007]
By implementing these methods in combination, it is possible to simultaneously excavate the entire upper half section up to the SL line 12 in tunnel excavation, and increase the excavation length (M dimension) per work cycle (for example, about 9 m). For example, there are a great number of cases where excavation is performed while providing a preceding reinforcing lap of approximately 3.5 m (P dimension).
[0008]
In the conventional long face bolt method, a general purpose drill jumbo commonly used in tunnel excavation is not used, but a special machine for slope anchor construction and underground boring is separately prepared at the base end side A, and the tunnel mirror surface 13 Although there is a method of placing a long face bolt 1 that is more stable by carrying out longer drilling holes, the method using a special machine has an adverse effect on the work cycle that is important in tunnels, as well as a special machine or special machine. Recently, it has been refrained from being expensive because of the necessity of workers, and here, an economical conventional long face bolt construction method using the most commonly used general-purpose drill jumbo will be described.
[0009]
[Prior art-1: FIT method]
As the conventional long face bolt method, the most practically used FIT (FRP Injection Tube) method is well known (for example, see Patent Document 1).
[0010]
Examples and details of this technology are also included in the tunnel technology development NPO “Geofronte Study Group”, the Long Bolt Subcommittee, the Cable Bolt Working Group, “Construction Survey and Analysis of Long Mirror Bolts, Part 2, It is introduced in detail in "Technical data on long bolt construction in bad ground", published on November 29, 2000.
[0011]
In this method, a drilling bit is attached to the tip of a drilling rod whose base end is connected to a general-purpose drill jumbo rock drill, and the tip of a short steel pipe containing the drilling rod is drilled into the drill bit. Connected to the rear end of the short steel pipe is a long reinforcing pipe with a plurality of horizontal holes made of fiber reinforced resin (made of FRP) that can be excised with a general-purpose excavator for subsequent excavation of the tunnel. Then, the hole drilling rod and the FRP reinforcing pipe are drilled into the ground in front of the face of the tunnel with the hole drilling bit at the tip while sequentially connecting the hole drilling rod and the long tube. When the drilling rod is recovered from the base end, the solidification material is injected from the inside over the entire internal length of the FRP reinforcing pipe left in the ground, and the periphery of the long pipe is It is built by filling or pressurizing and solidifying the natural ground It is a method for constructing a post-drilling possible long face bolt.
[0012]
This FIT method employs the double-pipe drilling method that has been widely used in slope anchoring work, and the drilling method is well-known. The inserted outer tube itself is a thick reinforcing tube made of FRP. The actual use case is an extremely thick glass fiber reinforced FRP tube with an outer diameter of φ76mm and a wall thickness of 8mm. Although it is necessary for the impact to be applied and compression due to collapse of the hole wall in the surrounding natural ground and the traction impact force from the tip bit side, it is necessary to prevent damage, but although the glass fiber reinforced FRP has a high tensile strength, it is comparable to the impact and impact It has a thick wall structure due to its fragile characteristics.
[0013]
Both ends of the thick-walled FRP reinforcing pipe are provided with male threads, and it is standard to use a coupler for connecting the reinforcing pipes. For example, a double pipe is placed while sequentially connecting the above-mentioned 3 m size reinforcing pipes. .
[0014]
The tensile strength of the FRP reinforcing pipe base material before the side hole processing is 1000 kN, but it is about 200 kN at the coupler connecting portion, and the connecting portion is a weak point.
[0015]
In the long face bolt described above, it is necessary to place approximately 12.5 to 25 m, so there are a plurality of connection points, and the face bolt builder effectively uses the axial tensile strength of the bolt. Therefore, it is expected that more efficient usage is expected for the tensile strength of the expensive FRP pipe.
[0016]
[Prior art-2: GSA method]
The GSA (Ground Spile Anchor) method is a construction method for rock bolts and ground anchors developed in Austria for defective grounds (see, for example, Patent Document 2).
[0017]
Examples and details of this technology are also included in the tunnel technology development NPO “Geofronte Study Group”, the Long Bolt Subcommittee, the Cable Bolt Working Group, “Construction Survey and Analysis of Long Mirror Bolts, Part 2, It is introduced in detail in "Technical data on long bolt construction in bad ground", published on November 29, 2000.
[0018]
In this method, a swivel device is additionally connected in front of a general-purpose drill jumbo rock drill, and a GSA bit consisting of a center bit that can be dropped off at the center and a ring bit that is later recovered together with a rod is relatively thick. A single pipe is drilled while sequentially connecting using male and female screws provided at both ends of a drill rod of a predetermined length (2 to 3 m) with meat.
[0019]
Drilling water is discharged from the GSA bit through the drill rod inner hole from the swivel device installed in front of the rock drill on the base end side, and the drilled slime passes between the drill rod and the ground hole wall. Is discharged to the base end.
[0020]
Once a predetermined long face bolt drilling hole (for example, about 12.5 m) is completed, the rod is released at the base end, and the entire length of the drill rod hollow part is free of braided connection weak points. Insert the FRP rope etc. manually.
[0021]
Once inserted to the end, manually hit the center bit of the GSA bit through the FRP rope, drop it forward, connect the drill rod at the base end to the swivel device again, and pass the solidified material through the drill rod. This is a technique for constructing a long face bolt by filling up to a bit and repeating additional filling (pressurizing filling as required) while releasing the rod.
[0022]
In this case, the long FRP rope can be manufactured in any of aramid, carbon, and glass types. Unlike other construction methods, the long FRP rope is long and coiled even if there is no coupler connection. It is possible to convey the outer diameter φ21 mm with a system fiber reinforced FRP: a tensile load of 300 kN is the maximum product diameter that can be packed in a coil with a diameter of about 2.0 m).
[0023]
The idea of the GSA method is that the drilling hole diameter is not larger than necessary and the FRP tensile load is not connected, so it can be said that it is very effective and economical. For long face bolts, for example, 12.5m Alternatively, a 25m drill rod is installed horizontally, an FRP rope is installed over the entire length, and the center bit of the GSA bit is securely dropped forward (because it is underground and cannot be visually confirmed), increasing the fluidity. However, if the drill rod is pulled out after injecting the solidified material that seems to have a considerable viscosity, the FRP rope material having a predetermined mass is likely to be pulled out together with the rod. Even if you use an FRP rope tip with a locking stopper that spreads out, dozens of centimeters before the locking tool pierces the ground There is a high possibility that it will be pulled out in units of several meters, and the work at the base end is complicated and various troubles are expected due to the fact that additional drilling or pressure injection is required each time the drill rod is further pulled out, As far as the inventor is aware, it seems not to be used much after the test construction.
[0024]
[Prior art-3: Small-P method]
This construction method is also a long face bolt construction method that has already been adopted a lot, and its contents are introduced in detail in the technical data issued by the `` Geofronte Study Group '', as a steel pipe tip receiving construction method and equipment used for the construction method, The non-widening construction technique for excising the end portion of a long steel pipe in the long tip receiving method (AGF method) is applied to a long face bolt construction (for example, see Patent Document 3).
[0025]
In addition, there are various other application examples of the long face bolt placing method using the same technique (see, for example, Patent Document 4).
[0026]
In the “AGF-P method” in which a resin pipe is used as a terminal pipe of a long steel pipe (referred to as a steel pipe P) and the resin pipe is excised, the steel pipe has a diameter of 100 to 120 mm, while the long face bolt has an outer pipe. The diameter is as small as about φ60 to 70 mm, and is commercialized as “Small-P Method”.
[0027]
In the Small-P method, a resin pipe having a diameter of about 60 mm is set at the tip, and a lost bit having a diameter slightly larger than that of the resin pipe is set at the tip, and driving and striking are transmitted from the rock drill at the base end by a drilling rod to drill.
[0028]
The resin tube is sheathed over almost the entire length (approximately 12 to 25 m) of the drilling rod, and is placed while being connected in a single unit of about 3 to 4 m. When the placement is completed, the lost bit at the tip is released, The drilling rod is collected from the base end side while the resin tube remains on the ground.
[0029]
The resin pipe left in the ground is provided with a plurality of lateral holes in the longitudinal direction, and a solidifying material is injected through the inner hole of the resin pipe, and is solidified by filling or pressurizing the surrounding ground.
[0030]
Long face bolts pre-reinforce excavation grounds by the axial tension of the bolts, but the tensile strength of the resin pipe is very small. In this method, the small diameter (for example, φ25mm) is placed inside the resin pipe before filling with the solidified material. In general, the carbon-based FRP bolts are connected and inserted every 4 to 6 m with a special coupler to form a reinforcing core material.
[0031]
However, even if the base material of the FRP core material has a shaft strength of, for example, about 380 kN, a long face bolt requires a plurality of connections, and the connection portion has a strength of, for example, about 180 kN, avoiding a decrease in shaft strength. I couldn't.
[0032]
Moreover, although the said resin pipe | tube in an Example is a thick pipe | tube of about 5-6 mm, it is guessed that the outer peripheral surface was smooth and the certainty of the adhesive force by a surrounding natural ground and a solidification material was concerned.
[0033]
In addition, a shock-resistant special resin pipe is used to prevent the connection screw part from being destroyed by impact or blow from the base end rock drill or drilling rod during long installation. Depending on the conditions, the energy transmitted from the rock drill is large, and there seems to be a concern about breakage.
[0034]
[Patent Document 1]
JP 2000-34882 A (pages 1-6, FIGS. 1-8)
[Patent Document 2]
JP 2001-3681 A (pages 1-5, FIGS. 1-9)
[Patent Document 3]
JP-A-8-121073 (pages 1-9, FIGS. 1-12)
[Patent Document 4]
JP 2000-320290 A (page 1 to page 3, FIGS. 1 to 6)
[0035]
[Problems to be solved by the invention]
In FIG. 16, the long tip receiving steel pipes 8 and 9 to be driven at the top of the face by the AGF method are generally 12.5 m, and the subsequent excavation is 9 m (M dimension).
This difference of 12.5m-9m = 3.5m (P dimension) is the lap length of the pre-receiver steel pipe. In normal AGF construction, excavation of 9m is repeated, and then the next shift of the long steel pipe is repeated.
[0036]
Therefore, in the long face bolt construction, the remaining length of the long face bolt 4 driven in the previous cycle and the same bolt 1 to be driven next are laps in accordance with this excavation length (M dimension). Economically realizing stable construction up to a minimum of 12.5m, preferably twice as much as 25m so as to be the length (P dimension) leads to a significant increase in work cycle efficiency.
[0037]
In addition, the solidifying material can be broadly divided into urethane and cement, but especially when it is injected under pressure for the purpose of penetrating a certain amount of ground in the injection of cement-based material, which requires time to start curing, Insufficient caulking at the mouth of the mirror surface 13 on the base end side A causes a leakage of the solidified material, and it has been reported that it is difficult to prevent leakage.
[0038]
In such a case, it was necessary to pressurize and inject the natural ground portion of 1.0 to 2.0 m near the mouth as a bulkhead and implement a countermeasure for leakage prevention.
[0039]
Therefore, in the present invention, the construction of various conventional methods described in the previous section, the construction of unique long face bolts that have improved technical difficulties and economic concerns, and in particular the pressure injection of cement-based solidified material It is an object of the present invention to provide a method for constructing a long face bolt capable of constructing an original mouth bulkhead in the case of performing the above.
[0040]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a construction of a long face bolt that can be excavated after being driven in a substantially excavation direction for the purpose of reinforcing a natural ground in front of the face in the excavation direction during tunnel excavation. Method Because A drilling bit is attached to the tip of a drilling rod whose base end is connected to a rock drill, and the tip of a short steel pipe containing the drilling rod is rotatably connected to the drilling bit. A long tube made of thin-walled steel spiral sheath, which can be excised with a general-purpose excavator in the subsequent excavation of the tunnel at the rear end of the short steel tube, has continuous spiral protrusions, and has a plurality of horizontal holes Connect the above-mentioned drilling rod and long tube in the ground in front of the face of the tunnel, in the same direction as the tunnel excavation direction, and sequentially connect the drilling rod and the long tube to the drill bit at the tip. After the drilling is completed and the drilling rod is collected from the base end, the base end extends over the substantially entire length of the inner space of the long pipe left in the natural ground. From the department side Post-drilling is possible Insert a long rod to be a reinforcing core, and then inject solidified material from the inside over the entire length of the long tube, and fill or penetrate and solidify the solidified material into the surrounding natural ground from the side hole of the long tube The configuration to be adopted is adopted.
[0041]
When injecting the solidified material into the long tube, when the solidified material is injected under pressure for the purpose of penetration of the solidified material sufficiently into the ground, a bulkhead intended to prevent the solidified material from leaking from the base end In order to ensure, two bag packers are arranged at predetermined bulkhead intervals on the base end side of the long rod in the long tube, and a required number of small holes are provided in the direction of bulkhead formation of each bag packer. Alternatively, urethane or the like may be injected into both bag packers at the same time to leak from the small hole, and the bulkhead may be constructed by penetrating and solidifying the surrounding natural ground from the side hole of the long tube in the bulkhead section. .
[0042]
Further, the long rod may be formed of a rope made of glass fiber, aramid fiber, or carbon fiber reinforced resin, or a solid or hollow long object.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0044]
In the tunnel excavation shown in FIG. 1, the construction method of the long face bolt 1 that can be excavated after being placed in the excavation direction for the purpose of reinforcing the natural ground in front of the excavation direction is as shown in FIG. Drilling bit 5 is attached to the tip of drilling rod 3 whose end A is connected to rock drill 6, and casing top 17 fixed to the tip of short steel pipe 14 containing drilling rod 3 is cut. It has a continuous spiral projection 2a that is connected to the hole bit 5 through a rotatable ring 21 that is rotatable, and has a continuous spiral projection 2a that can be excised with a general-purpose excavator in the subsequent excavation of the tunnel at the rear end of the short steel pipe 14. The long tube 2 made of a thin steel spiral sheath in which the horizontal holes 28 are arranged is connected.
[0045]
The above-mentioned drilling rod 3 and the long tube 2 made of a steel spiral sheath are successively added to the ground in front of the face of the tunnel in the same direction as the tunnel excavation direction while the drilling rod 3 and the long tube 2 are sequentially added. Drilling is performed with a drill bit 5 at the tip.
After the drilling rod 3 is recovered from the base end when the placement is completed, the base end A side of FIG. Thru | or a long glass fiber, an aramid fiber, or a carbon fiber reinforced resin (FRP) rope 32 or a solid or hollow long rod 31 as shown in FIG. The solidified material is injected from the inside over the entire length of the long tube, and the surrounding natural ground is filled or pressurized infiltrated and solidified from the side hole 28 of the long tube, and can be excavated later. A method of constructing a long face bolt 1 that is surely attached is taken.
[0046]
In the double pipe drilling of the long face bolt 1, it is a commercial standard product that has a spiral protrusion 2a over its entire length, used as a steel sheath for prestressed concrete work that has not been used for outer pipes in the past. The long tube 2 made of economical steel spiral sheath is used, and the size of this steel spiral sheath is, for example, a standard product thickness of a maximum outer diameter φ77 mm and a minimum inner diameter φ70 mm of 0.4 mm, but 15 m For drilling holes of up to, for example, about 25 m, a custom-made thick product (for example, about 0.5 to 0.8 mm) may be used depending on natural ground conditions.
[0047]
The long tube 2 made of the above steel spiral sheath has a large shell rigidity due to the provision of the continuous spiral protrusion 2a even if the wall thickness is thin, and is not deformed by the surrounding natural ground when drilling, and has a relatively large shape. In the presence of the continuous spiral protrusion 2a, the FRP reinforcing core material by the solidification material injection and the steel spiral sheath inner surface, and the steel spiral sheath outer surface and the surrounding natural ground are reliably transmitted economically, and Realized reliably.
[0048]
In the present invention, in the selection of the FRP reinforcing core material to be inserted after installation inside the long tube 2 made of steel spiral sheath, it is relatively inexpensive in the construction of a short face bolt of 6 m or less in a special case. If a hollow or solid glass fiber FRP bolt 31 is used, it can be transported in a rod form without the need for a coupler or the like. Although it is slightly expensive, using the FRP rope 32 and eliminating the reduction of the axial force due to the connection of the FRP is economical because the tensile strength of the core material can be maximized.
[0049]
As for the FRP rope 32, the glass fiber system has the most cost-effective tensile strength effect at present, but the carbon fiber system and the aramid fiber system having high strength orientation may be used.
[0050]
The diameters of these FRP ropes 32 are preferably ropes that can be transported in a normal track and can be packed in a coil shape with a winding diameter of about 2.0 m. Incidentally, at the present time, the maximum product diameter that can be wound into a coil shape of about φ2.0 m in a glass fiber system is φ21 mm, and its tensile breaking load is about 300 kN.
[0051]
Further, in the case where the solidifying material is cement-based, and for the bulkhead forming means for the purpose of preventing the solidifying material leak from the base end portion when pressure is injected for the purpose of penetration of some natural ground, FIG. 12 and FIG. As shown in FIG. 13, two bag packers 44 and 45 are provided at the base end side A of the FRP rope 32 or FRP long rod 31 to be inserted later at a predetermined bulkhead interval (L = 1 to 2 m). 1 and a plurality of small holes 46 are formed in the direction of forming the bulkhead of each bag packer 44 and 45, and a foaming injection material such as urethane is simultaneously injected into both bag packers 44 and 45. Then, a technique is adopted in which measures are taken to prevent leakage of cement-based solidified material that is infiltrated and solidified into the surrounding natural ground from the lateral hole 28 of the steel spiral sheath in the bulkhead section and reliably injected later.
[0052]
FIG. 1 is a work state diagram in which a long tip receiving method (AGF method) and the long face bolt method of the present invention are used together in tunnel excavation in a relatively unnatural ground, and an AGF steel pipe of the previous cycle. 8 and long face bolts 4 and the subsequent excavation section (M) are completed, and in preparation for the next cycle excavation (M), the AGF steel pipe 9 at the top of the face is completed. Then, the long face bolt 1 has been driven from the mirror surface 13, and the next long face bolt 1 'has been driven.
[0053]
On the base end side A, a rock drill 6 mounted on the guide cell 7 of the drill jumbo 10 is set on the mirror surface 13 in the tunnel excavation direction, and the rotation and hitting of the rock drill 6 is longitudinal. Is transmitted to the drill bit 5 at the tip via the drill rod 3 set inside the long tube 2 made of steel spiral sheath provided with a plurality of lateral holes 28.
[0054]
Drilling water is supplied from the rock drilling machine 6 to the bit part 5 at the tip through the inner hole 19 of the drilling rod 3 shown in FIG. 2, and the generated drilling slime is a through hole 26 a provided in front of the bit part 5. It passes through the gap through hole 26 between the long tube 2 and the drilling rod 3, passes to the base end side A, and is discharged from the end of the long tube 2.
[0055]
A configuration example of the bit unit 5 will be described in more detail with reference to FIGS.
[0056]
A casing top 17 having the same outer diameter as that of the short steel pipe 14 is welded and fixed to the distal end portion of the short steel pipe 14, and after the completion of the casting, the rostrox bit having a diameter slightly larger than that of the short steel pipe 14 to be left in the natural ground. 18 is rotatably connected to the casing top 17 via a circumferential ring 21, and a connecting part 25 for screwing a steel spiral sheath, which is the subsequent long pipe 2, to the rear part of the short steel pipe 14. Is fixed by welding.
[0057]
A center bit 15 to be recovered later is connected to the distal end portion of the drilling rod 3 by a screw connection portion 20.
[0058]
The center bit 15 transmits the rotation and striking transmitted from the drilling rod 3 to the rostring bit 18 through the protrusion 16, and the drilling water sent from the rock drill 6 on the proximal end side is the drilling rod. 3 is supplied from the center bit drain port 23 through the inner hole 19, and the drilling slime passes through the through hole 26 a on the front surface of the bit and is discharged from the through hole 26 between the long tube 2 and the drilling rod 3 to the base end. Proceed with drilling operations.
[0059]
Further, as the drilling operation proceeds, the long tube 2 is pulled by hitting the inner projection of the casing top 17 via the rear projection 24 provided on the center bit 15.
[0060]
As shown in FIG. 7, the drilling rod 3 is a general-purpose hollow rod having a length of about 3 m to 3.6 m that has been conventionally used, has male threads 20 at both ends, and is connected while being connected by a coupler 29. To proceed.
[0061]
Further, in the present embodiment, the long tube 2 made of a steel spiral sheath that is placed on the drilling rod 3 and is driven, as shown in FIG. 5, has a maximum outer diameter φ77 mm, a minimum inner diameter φ70 mm, a wall thickness of 0. 6 having a size of 4 mm and substantially the same length as the drilling rod 3, as shown in FIG. 6, for example, is connected by a coupling body 27 in which two sheath connection parts 25 of FIG. Proceed with drilling.
[0062]
When the predetermined length of drilling of the long face bolt 1 (M + P dimension in FIG. 1) is completed, the drilling rod 3 and the center bit 15 at the distal end are collected from the base end side A, and in the longitudinal direction constituting the substantially full length. The FRP rope 32 or the FRP rod 31 is inserted into the inner hole of the long tube 2 made of a steel spiral sheath having a plurality of lateral holes 28.
[0063]
FIG. 10 shows an FRP rope 32 to be inserted, which is used in the case of a long object having a length of 6.5 m or more and is wound in a coil shape so as to have a diameter of about φ2 to 2.3 m so that truck transportation is possible. Delivered.
[0064]
Even when the coil is unwound after arrival at the site, the curl remains, and for example, a curl with a diameter of about φ10 m is generated, so that the tip is connected to the inner protrusion of the coupling body 27 for connecting the long tube or the long tube 2 by manual insertion. A tip cone 38 is arranged for avoiding the remaining drilling slime and the like and facilitating insertion.
[0065]
Further, in this case, the solidified material is injected from the base end side A toward the back side of the long tube 2 by the short injection hose 34 through the ball valve 36, and resistance is applied by the air pressure with which the solidified material is sealed. The return tube 37 is arranged up to the tip of the FRP rope 32 so as not to receive it, and after the air venting and filling are completed, the leakage of the solidified material is confirmed on the base end side A, so that complete filling in the hole can be performed. Yes.
[0066]
FIG. 11 shows a plug structure at the mouth of the mirror surface 13 when no pressure is applied in filling the solidified material of the long face bolt.
[0067]
In the gap between the sprayed concrete on the mirror surface 13 and the long tube 2, a mouth caulking 43 made of waste cloth or resin is implemented, and a rubber ring is provided at the end of the long tube 2 made of a steel spiral sheath protruding from the mirror surface 13. An end metal fitting 39 is fixed so as to hold 40, and an FRP rope 32, an injection short hose 34, and a return tube 37 are set so as to penetrate the rubber cone 41, and the rubber cone is attached to ensure liquid tightness. It is pushed in by the pressing lid 42.
[0068]
The solidified material is injected from the short injection hose 34 through the ball valve 36, filled over the entire length of the long tube, and overflows and leaks through the distal end hole of the return tube 37 on the proximal end side.
[0069]
When leakage from the return tube 37 is confirmed, the tube is folded and taped, and the ball valve 36 on the injection side is tightened to complete the injection.
[0070]
FIG. 9 shows a configuration example of the FRP core material when the long face bolt is as short as about 6 m. In this example, a hollow FRP rod 31 having a maximum length of about 6 m is employed. Up to 6m can be easily transported by truck and on-site in a rod shape, and the rod-shaped FRP is more economical than the same rope product.
[0071]
As described above, a tip cone 33 for easy insertion is provided at the tip, a solid material is filled from the mouth side by a short hose 34 provided with a ball valve 36, and air is vented from the tip hole 31 'of the hollow FRP rod 31. If the solidification material leak on the base end side A of the rod 31 is confirmed, the plug 35 is inserted to complete the filling. The mouth coking in this case is not shown.
[0072]
In the injection of the solidifying material, “no-pressure filling” for the purpose of ensuring only the adhesive force between the inserted FRP core material and the surrounding ground has been described. However, as another implementation method, not only ensuring the adhesive force but also solidifying material. There is also a case of “pressure permeation injection” in which a certain amount of is injected into the surrounding ground.
[0073]
In this case, it is necessary to subject the mouth part near the mirror part 13 to the surrounding ground and the isolated coking process over a range of about 1 to 2 m and then pressurize and inject the caulk forming part as “bulk head”. Called.
[0074]
There are various methods for forming the bulkhead. Here, an extremely simple and economical method for forming a bulkhead that can be employed in the practice of the present invention will be described.
[0075]
12 and 13 employ the FRP hollow rod 31 having a relatively short length of up to about 6 m and the long FRP rope 32 described in the previous stage, and the long tube 2 to obtain the bulkhead. It is a block diagram of the FRP core material inserted later.
[0076]
In the FRP hollow rod 31 and the FRP rope 32, two bag packers 44 and 45 are arranged in the bulkhead formation section (L dimension) at the injection side mouth, and the inner side of the long tube 2 that is placed is almost the entire length. For example, urethane-based expansible injection into these two bag packers 44 and 45 disposed inside the long tube 2 in the vicinity of the outlet on the base end side A of the FRP core member inserted after the The material is injected and leaked from the small holes 46 of the bag packers 44, 45 provided in the direction of forming the bulkhead, and further leaked into the surrounding ground from the side holes 28 of the steel spiral sheath, so that a reliable bulkhead can be obtained. To form.
[0077]
An example of the long FRP rope 32 shown in FIG. 13 will be described in more detail with reference to FIGS. 14 and 15.
[0078]
FIG. 14 is a schematic view of the length of the steel spiral sheath long tube 2 having a plurality of lateral holes 28 that is installed in advance in the natural ground according to the present invention, at the most proximal end side, at the exit of the mirror unit 13. A 3 m long terminal tube 2 'is shown.
[0079]
In the normal long face bolt construction, the horizontal holes 28 are pipe through holes having a hole diameter of about 10 mm, and are generally arranged in a staggered manner at intervals of about 250 mm to 300 mm.
[0080]
When the target bulkhead section (L) is set to 1.2 m, for example, the lateral holes 28 of the long tube 2 'of the portion are arranged somewhat densely so that the penetration into the surrounding ground is easy and reliable.
[0081]
In this example, taking into account the mouth work allowance (N dimension) and the width of the bag packers 44 and 45, 1.2 m from the position 350 mm (N dimension) from the base end side A end of the long tube 2 '. Staggered horizontal holes 28 are formed every 10 cm in the section of (L dimension).
[0082]
In FIG. 15, the terminal long tube 2 ′ is driven so as to slightly protrude from the mirror surface 13 on the base end side, and the drilling rod 3 has already been recovered, and the FRP rope 32, the injection hose 34, the return tube 37, In addition, bag packers 44 and 45 installed at intervals of about 1 m at the mouth portion are inserted and set.
[0083]
In this state, urethane-based inflatable injection material (for example, silica resin) is injected into the bag packers 44 and 45 from the injection hoses 47 and 48 substantially simultaneously.
[0084]
The injection material first leaks from the small hole 46 provided on the bulkhead forming side while inflating the bag packers 44 and 45 and inflating and contacting the inner surface of the long tube 2 ′ with an appropriate pressure. The bulkhead 49 is surely formed in the vicinity of the mirror part 13 by filling the inner surface of the part and continuously solidifying it in the surrounding natural ground near the mouth from the side hole 28 of the long tube 2 ′ which is arranged somewhat densely continuously. Can do.
[0085]
Thereafter, the solidified material is injected from the ball valve 36 in the manner described above, and the leakage of the solidified material through the distal end hole of the return tube 37 arranged to the vicinity of the distal end of the long FRP rope 32 causes the proximal end portion. If it can be confirmed on the side A, the return tube 37 is folded and closed securely, the injection pressure on the ball valve 36 side is raised to a predetermined value and held for a predetermined time, and then the ball valve 36 is closed to ensure a reliable “pressure permeation” Injection "can be performed.
[0086]
【The invention's effect】
As described above, according to the present invention, at the time of tunnel excavation, in the construction method of a long face bolt that can be excavated after being placed for the purpose of reinforcing natural ground in front of the face, the base end is connected to the rock drill. A drilling bit is attached to the tip of the drilling rod, the tip of the short steel pipe containing the drilling rod is rotatably connected to the drilling bit, and a plurality of pipes are attached to the rear end of the short steel pipe. Connect a long tube made of a thin steel spiral sheath with a horizontal hole, and connect the drilling rod and long tube in the ground in front of the face of the tunnel in the same direction as the tunnel excavation direction. After drilling with a drilling bit and placing it, the drilling rod is collected from the base end, and then made into FRP to the full length of the inside of the long pipe left in the natural ground. A long rope or rod, and then solidify from the inside over the entire length of the long tube Since the solid material is filled or infiltrated and solidified in the surrounding natural ground from the horizontal hole of the long tube, the long tube made of steel spiral sheath has a continuous spiral protrusion even though the wall thickness is thin. Because of this, the shell stiffness is large, it is not deformed by the surrounding natural ground when drilling, and the long spiral rope or rod made of FRP that becomes the reinforcing core material by injecting solidified material due to the presence of the relatively spiral shaped continuous spiral projection Therefore, it is possible to economically and reliably construct a long face bolt by reliably transmitting the adhesive force between the inner surface of the steel spiral sheath and between the outer surface of the steel spiral sheath and the surrounding ground.
[0087]
In addition, in injecting the solidified material into the long tube, two bag packers are arranged at a predetermined bulkhead interval on the base end side of the long rod in the long tube, and the bulkhead forming direction of each bag packer The required number of small holes are provided in the tank, and urethane or the like is injected into both bag packers at the same time to leak from the small holes, and then infiltrate and solidify into the surrounding natural ground from the side holes of the long tube in the bulkhead section. Therefore, it is possible to construct an original mouth bulkhead particularly when a cement-based solidified material is injected under pressure.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of a tunnel upper section excavation state where a long face bolt of the present invention is installed.
FIG. 2 is an enlarged vertical side view of the structure of a bit portion for placing a long face bolt of the present invention.
FIG. 3 is a front view of the bit part.
FIG. 4 is a partially cutaway side view of a connecting part that connects a long steel pipe made of a spiral sheath and a short steel pipe of a bit part.
FIG. 5 is a side view showing a long tube made of a steel spiral sheath in which a plurality of lateral holes are arranged.
FIG. 6 is a side view of a coupling body that connects the long tubes to each other.
FIG. 7 is a side view of a drilling rod for supplying rotation and blow of a rock drill and drilling water to a tip bit.
FIG. 8 is a longitudinal side view of a connection coupling for connecting the drilling rod.
FIG. 9 is a side view showing the structure of a non-pressurized, filling injection FRP hollow rod core material that is subsequently inserted into a long face bolt of the present invention up to a length of approximately 6 m.
FIG. 10 is a side view showing the configuration of a non-pressurized, filling injection FRP rope core material to be inserted later into the long face bolt of the present invention having a length of approximately 6.5 m or more.
FIG. 11 is a longitudinal side view showing a mouth lid structure in a non-pressurized and filling injection of a long face bolt according to the present invention using an FRP rope core material.
FIG. 12 is a side view showing the configuration of a FRP hollow rod core material for pressurization and osmotic injection that is inserted into the long face bolt of the present invention up to a length of approximately 6 m.
FIG. 13 is a side view showing the structure of a pressure and osmotic injection FRP rope core material to be inserted later into the long face bolt of the present invention having a length of approximately 6.5 m or more.
FIG. 14 is a side view showing a terminal long tube made of a steel spiral sheath.
FIG. 15 is a longitudinal side view showing a construction state of a bulkhead according to the present invention for performing pressurization and osmotic injection.
FIG. 16 is a longitudinal side view of a section excavated above a tunnel in which a long face bolt is placed in a conventional long tip receiving method.
FIG. 17 is a front view of the above.
[Explanation of symbols]
A Base end side
1 Long face bolt installed
1 'Long face bolt during installation
2 Long tube made of steel spiral sheath
2 'Long tube made of steel spiral sheath on the most proximal side
2a Spiral protrusion
3 Drilling rod
4 Long face bolts placed in the previous cycle
5 Drilling bit
6 Jackhammer
7 Guide cell
8 Long steel pipes cast in the previous cycle
9 Long steel pipes cast in this cycle
10 Drill jumbo
11 Tunnel top edge finish line
12 Upper half drilling line
13 Mirror surface (mirror part)
14 Short steel pipe
15 Center bit
16 Center bit forward projection
17 Casing top
18 Rostring bits
19 Inner hole
20 screws
21 Circumferential ring
22 Inner hole of center bit
23 Center bit drain
24 Rear protrusion of center bit
25 Sheath connection parts
26 through holes
26a Front hole in front of bit
27 Coupling body for long tubes
28 Horizontal hole of long tube
29 Drilling rod coupling
30 Connection screw for coupling
31 Hollow FRP bolt
31 'Tip hole
32 Solid FRP rope
33 Tip cone
34 Injection hose
35 stoppers
36 Ball valve
37 Return tube
38 Tip cone
39 End hardware
40 Rubber ring
41 Rubber cone
42 Holding lid
43 Mouth Caulking
44 Bag Packer
45 bag packer
46 Small hole
47 Injection hose for bag packer
48 Injection hose for bag packer
49 Bulkhead
50 Steel support
50a Minimum steel support
50b Intermediate steel support
50c Maximum steel support
L Bulkhead section
N End length of the long tube

Claims (3)

This is a long face bolt construction method that can be excavated after tunneling in the direction of the excavation direction for the purpose of reinforcing natural ground in front of the face in the excavation direction, and the base end is connected to a rock drill. A drill bit is attached to the tip of the drilled rod, the tip of the short steel pipe containing the drill rod is rotatably connected to the drill bit, and the tunnel is connected to the rear end of the short steel pipe. In a subsequent excavation, it can be excised with a general-purpose excavator, connected to a long tube made of a thin steel spiral sheath, having a continuous spiral projection, and provided with a plurality of lateral holes. A long pipe is drilled into the ground in front of the tunnel face in the same direction as the tunnel excavation direction by drilling with a drill bit at the tip while sequentially connecting the drill rod and the long pipe. When installation is complete, rotate the drilling rod from the base end. After, over substantially the entire length the inner space of the long tube which is left on the natural ground, inserting an elongate rod as the rear excavation capable reinforcing core from the base end, then, the length The solidified material is injected from the inside over the entire length of the long tube, and the solid material is filled or infiltrated and solidified from the side hole of the long tube toward the tunnel excavation direction. Construction method of long face bolts that can be excavated later . When injecting the solidified material into the long pipe, when the solidified material is injected under pressure for the purpose of infiltrating the solidified material sufficiently into the ground, a bulkhead intended to prevent the solidified material from leaking from the base end In order to ensure, two bag packers are arranged at predetermined bulkhead intervals on the base end side of the long rod in the long tube, and a required number of small holes are provided in the direction of bulkhead formation of each bag packer. In addition, urethane and the like are simultaneously injected into both bag packers to leak this from the small hole, and the bulkhead is constructed by penetrating and solidifying the surrounding natural ground from the side hole of the long tube in the bulkhead section. The construction method of the long face bolt which can be excavated after being driven in the tunnel excavation direction of Claim 1. The long rod capable said rear excavation claims, characterized in that used as glass fibers, aramid fibers or also a carbon fiber reinforced plastic rope, is formed in one of the middle empty long object A construction method of a long face bolt capable of being excavated after being driven in the tunnel excavation direction according to Item 1.

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