JP4942210B2 - Ground reinforcement method - Google Patents

Description

  The present invention relates to a ground reinforcement method such as a tip receiving work or a mirror reinforcement work for reinforcing a front ground when excavating a tunnel, for example, a hole is formed in the front ground to be excavated, and at the same time, a reinforcing pipe is provided in the hole. The present invention relates to a natural ground reinforcement method for insertion and reinforcement. More specifically, for example, a steel pipe is used as the reinforcing pipe in a so-called double pipe type drilling apparatus in which a drilling hole is formed around a hollow tubular drilling rod having a drilling bit at the tip in a state where the reinforcing pipe is arranged. The drilling pipe is pulled into the drilling hole while drilling with the drilling bit, and cemented or resin-based solidified material is injected from the reinforcing pipe to fix the ground. In addition to rubbing, the present invention relates to a natural ground reinforcement method that is particularly effective when the reinforcing pipe is placed in a natural ground in front of the face for reinforcement.

  Conventionally, when a tunnel is excavated in, for example, a natural ground having poor geological conditions, the forward natural mountain to be excavated is constrained by a reinforcing material such as a steel pipe and the tunnel is dug while being reinforced. As a natural ground reinforcement method for excavating a tunnel while restraining and reinforcing such a forward natural ground with a reinforcing material, in particular, a reinforcing pipe such as a steel pipe, the top or front of the forward natural ground where the tunnel should be excavated When drilling a hole in the ground and simultaneously inserting the reinforcing tube into the drilling hole, the hole is drilled in a state where the reinforcing tube is disposed around a hollow tubular drilling rod having a drilling bit at the tip. A so-called double pipe type long hole drilling device is used to form a hole, and a reinforcement pipe formed by connecting a single pipe or multiple pipes in sequence is placed as a tunnel face leading or mirror reinforcement work. It has been proposed to reinforce natural ground by injecting cement-type or resin-type solidified material into the reinforcing pipe to form a fixed or consolidated area in the reinforcing pipe and surrounding ground.

  The following Patent Documents 1 and 2 show an example of a natural ground reinforcement method using the above-described reinforcing pipe, and Patent Document 1 shows a predetermined elevation angle as a long tip receiving work by non-widening without widening the tunnel cross section. Among the reinforcing pipes laid in the section, the section located in the face mirror part at the rearmost end from the outer periphery of the tunnel excavation cross section, the reinforcement pipe of the excision section within the so-called tunnel excavation cross section (hereinafter referred to as the rear reinforcement pipe), It can be easily excised so that it can be constructed without providing a section widening section. In the above example, a tube made of synthetic resin such as vinyl chloride is used as the rear reinforcement tube so that it can be easily excised by a drilling machine during tunnel excavation. The rear reinforcement tube is built in front of the face. Each time a tunnel is excavated by a predetermined length (usually about 1 m) before being installed in the ground, it is buried in a natural ground within a range of about 3 m of the steel support. So that it can be excised.

  Moreover, the above-mentioned patent document 2 discloses a method for reinforcing a natural ground when excavating a tunnel while restraining the front ground, before drilling from the face to the mirror surface in the tunnel excavation section of the front ground (pipe). Reinforcing pipes such as steel pipe pipes that are inserted into the drilling holes are provided with slit-shaped cutout pores extending in the circumferential direction on the peripheral wall, and the above-mentioned reinforcement is made using an injection pipe that is inserted at the time of injecting the consolidated material Cement or resin-based solidified material is injected into the surrounding natural ground through the cut-out pores and discharge holes (injection holes) of the pipe, fixing with the natural ground, and fixing the natural ground around the reinforcing pipe The restraint effect of the ground in front of the face is enhanced by reinforcement.

  However, in Patent Document 1, a synthetic resin pipe is used as a rear reinforcement pipe in the excision section extending from the outer peripheral line of the tunnel excavation section to the face mirror part at the rearmost end among the reinforcement pipes driven at a predetermined elevation angle. However, the above excision section is a source of looseness that is also the cause of the preceding displacement during tunnel excavation, and the reinforcing pipe usually has a smooth outer peripheral surface, and excision during tunnel excavation is easy. However, since the adhesion effect of the above-mentioned reinforcing pipe and drilling hole due to the consolidated material is not taken into account, in the case of a fragile ground condition, the natural ground restraint force is inferior, resulting in loosening as a result. As a result of the gradual increase, the receiving effect decreases.

  Moreover, in the mirror reinforcement work of patent document 2, before excavation, a drilling hole (pipe insertion hole) is made from the face to the mirror surface in the tunnel excavation section of the front ground, and a steel pipe pipe or the like to be inserted into this drilling hole is used. Since the surface of the reinforcement pipe is smooth, in the case of fragile ground conditions, the stress generated in this reinforcement pipe is dominated by the axial stress. It is necessary to suppress the extrusion behavior of the natural ground due to the adhesion effect of the material, and in this situation, the tightness of the bottom of the reinforcing pipe and the peripheral surface are smooth pipes. Since it is inferior, the looseness may gradually increase and the stability of the face may decrease.

  Accordingly, in both Patent Documents 1 and 2, a cemented or resin-based solidified material is injected into the surrounding natural ground through the discharge hole of the peripheral wall of the reinforcing pipe, and the natural ground of the peripheral wall of the reinforcing pipe is fixed and reinforced. This is a method to increase the restraint effect of the ground in front of the face and measure the stability of the face, but since the peripheral surface of the reinforcement pipe is smooth, the restraint force due to adhesion is inferior in weak ground conditions Reinforcement is often performed separately.

  The long tip receiving work like Patent Documents 1 and 2 is capable of long tip receiving that can cope with various ground conditions, so it is possible to suppress the leading displacement of the ground, prevent looseness of the ground, and safety of construction. It is used for the purpose of ensuring safety. FIGS. 10 and 11 show the long steel pipe tip receiving method in which the tunnel excavation cross section is not widened in the natural ground. The face of the tunnel space T (the face of the tunnel excavation where the natural ground 1 has already been excavated) is shown. A reinforcing pipe 6 made of steel pipe or the like is placed in the natural ground 1 from the mirror part) 1a, and a rear reinforcing pipe 62, which is a reinforcing pipe in the excision section L from the outer peripheral line of the tunnel excavation section to the face mirror part at the rearmost end, The part exposed from the natural ground 1 with the excavation of the natural ground is formed of a tube that can be excised. As the rear reinforcing pipe 62, a pipe that can be excised according to the progress of tunnel excavation (1 m) and the discharge hole of the binder on the peripheral surface is used. A vinyl chloride pipe is used as the injection pipe 10 to be inserted at the time of injection in this construction method. By injecting a cement-type or resin-type solidified material into the reinforcing pipe 6 through the injection pipe 10, The fixing material is infiltrated into the reinforcing pipe 6 and the surrounding natural ground 1 to increase the bonding force between the rock pieces or the soil particles, so that the fixing and fixing region 8 is provided around the reinforcing pipe 6 as a receiving material. By forming it, the restraint effect of the ground in front of the face is enhanced.

  However, in addition to the fact that natural grounds that require the above-mentioned receiving method are inherently fragile, natural grounds near the face are prone to loosening due to excavation. For example, FIG. 12 shows the behavior around the face obtained from an analytical viewpoint, as well as the face behavior during construction in a fragile ground condition. However, the existing reinforced pipe cut off at the top edge of the face shown in FIGS. 10 and 13 and the natural ground area in the section located on the outer circumference of the tunnel excavation cross section are used for stress release during tunnel excavation as shown in FIG. The natural ground behavior (extrusion behavior) 1s of the mirror part due to the accompanying looseness occurs in the excavation cross-section space direction. Due to this influence, the reinforcing tube 6, particularly the rear reinforcing tube 62, generates large axial stress and bending stress due to the extrusion behavior, and the front reinforcing tube 61 of the reinforcing tube 6 already placed above and the rear reinforcing tube 61, Although the separation from the rear reinforcing pipe 62 of the reinforcing pipe 6 placed from the rear is large, fixing between the rear reinforcing pipe 62 and the ground 1 around the hole wall by injection is the most important section. Since the outer peripheral surface of the resin pipe used is smooth and inferior in adhesion strength, depending on the fragile ground condition, sufficient adhesion is secured by the consolidated material between the rear reinforcement pipe 62 and the ground. However, as the tunnel excavation progresses, the looseness of the surrounding ground gradually increases. As a result, the stability of the top end of the face is impaired due to insufficient fixing force with the reinforcing pipe 6. As a result, there is a disadvantage that a proper ground reinforcement effect cannot be obtained with a cement-based or resin-based solidified material.

  When injecting the consolidated material, as shown in FIG. 11, an injection pipe 10 inserted into the reinforcement pipe 6 is used to enter the surrounding natural mountain 1 from the discharge holes formed in the reinforcement pipe 6 and its peripheral wall. A consolidation material is injected to form a consolidation region and is fixed. However, slime is easily deposited at the bottom of the reinforcement tube 6 and the reinforcement tube itself is located below the hole wall as shown in the figure. In many cases, the discharge hole in the lower portion becomes ineffective in a closed state, and the consolidated region due to the consolidated material is easily formed only in the upper portion of the reinforcing tube 6, and the outer peripheral surface of the reinforcing tube itself is smooth. Therefore, it is difficult to secure fixing of the natural ground 1 and the reinforcing pipe 6 by the consolidated material. Accordingly, a required fixing region is not secured in the natural ground around the reinforcing pipe, and the pushing behavior of the face 1a is increased from the natural behavior 1s, and the required adhesion strength of the material capable of withstanding the behavior can be sufficiently exhibited. Since there is no natural ground restraining force, the stability of the face is impaired by loosening of the natural ground area around the reinforcing pipe and the gradual increase in the pushing behavior of the mirror part, and additional reinforcement is required due to concerns about restraining force. In some cases, it is difficult to say that the natural ground reinforcement effect is sufficient.

  FIG. 14 shows a method of reinforcing the ground in front of the tunnel excavation cross section with a reinforcing pipe 6 as a long mirror reinforcing member. In the tunnel space T, a reinforcement made of steel pipe or the like from the face 1a to the ground 1 is shown. A tube 6 is driven. As the long reinforcing pipe 6, a GFRP pipe that is easy to excise during tunnel excavation and has a high adhering effect by the caking material is generally used. Here, the caulking material discharge hole and the tunnel excavation progress ( A steel pipe having an annular groove (360 °) that can be cut in accordance with 1 m) is used. In this construction method, cement-based or resin-based solidified material is injected, and the reinforcing tube 6 and the solidified material injected into the surrounding ground 1 are used to increase the bonding force between rock fragments or soil particles. By forming the fixing and consolidation region 8 around the surface, the effect of restraining the ground in front of the face is enhanced. However, in addition to the natural weakness of the natural ground where the face reinforcement work (front receiving work / mirror reinforcement work) as described above is required, the natural ground near the face is prone to loosening due to excavation. It is. For example, FIG. 12 shows the behavior around the face obtained from an analytical viewpoint, as well as the face behavior during construction in a fragile ground condition.

  However, as shown in FIG. 12, the natural ground region in the section of the face mirror part shown in FIG. 14 is affected by the looseness caused by the stress release during tunnel excavation, and the pushing behavior of the mirror part becomes the tunnel space (excavation cross section). Space) occurs in the direction of T. Due to this influence, large axial stress and bending stress due to the extrusion behavior are generated in the section of the front natural ground 1b of the mirror part, and fixing of the long reinforcing pipe 6 and the natural ground 1 by injection is the most important. Since the steel pipe circumference used in this is a smooth material and has poor adhesion strength, depending on the fragile ground conditions where adhesion by the consolidated material is not secured, tunnel excavation progresses gradually and the surrounding ground As a result of the gradual increase of the looseness, the stability of the face mirror part and the top end part is impaired due to insufficient fixing force with the already reinforced pipe. As a result, an inconvenience that a proper ground reinforcement effect cannot be obtained with a cement-based or resin-based solidified material occurs. The required fixing of the reinforcing pipe and the surrounding natural ground is not ensured, and the pushing behavior of the face 1a is increased from the natural ground behavior 1s shown in FIG. 12, and the necessary strength of the material capable of withstanding the behavior is fully exhibited. Since it does not have the restraint force of the natural ground, the stability of the face is lost due to the looseness of the natural ground region around the reinforcement pipe and the gradual increase of the extrusion behavior of the mirror part, and additional reinforcement is made due to concerns about the restraint force. It may occur, and it is difficult to say that the natural ground reinforcement effect is sufficient.

JP-A-8-121073 JP-A-4-357293

  The present invention has been made in view of the above problems, and in accordance with the extrusion behavior that is the release stress at the time of tunnel excavation, a reinforcement pipe in a ground reinforcement method such as a tip receiving work or a mirror reinforcement work that has been placed from a tunnel excavation section. The natural ground in the area where is located can suppress the gradual increase of peeling and loosening caused by insufficient fixation or improvement of the peripheral wall of the reinforcing pipe with cement or resin-based solidified material, and can exert a highly uniform injection reinforcement effect In addition, there is no need for additional reinforcement at the time of tunnel excavation work, it is possible to obtain a suitable ground reinforcement effect, and to provide a ground reinforcement method that can be implemented at low cost in various excavation methods. Objective.

In order to achieve the above object, the ground reinforcement method according to the present invention has the following configuration. That is, it is formed by drilling a hole at a predetermined elevation angle from the tunnel excavation cross section to the ground in front of the face, and simultaneously connecting a single pipe or a plurality of pipes having a discharge hole for a consolidated material on the peripheral wall. In a natural ground reinforcement construction method in which a reinforcing pipe is placed in the drilling hole, and a consolidated material is injected into the reinforcing pipe to form a fixing or consolidated area in the reinforcing pipe and surrounding natural ground. in the vicinity of the discharge hole formed in the tube of a single tube or a plurality of forming the reinforcing tube, only the tube and integrally set a projection projecting outwardly of the tube, the tube in the vicinity of the discharge hole The protrusion is formed integrally with the pipe by projecting a part of the pipe to the outside of the pipe .

The protrusion may be formed, for example, in the vicinity of the discharge hole by integrally fixing a member (protrusion forming member) protruding outward of the pipe to the outer peripheral surface of the pipe by welding or the like. At least the rear end of the single tube or a plurality of tubes forming a or the reinforcing tube, an annular groove leaving a wall thickness that can be cut with tunnel boring machine as required, the longitudinal direction of the reinforcing tube You may make it provide the longitudinal slit which can be extended | stretched and can discharge the said consolidated material.

  According to the natural ground reinforcement method according to the present invention configured as described above, for example, in a receiving work or a mirror reinforcement work, in the vicinity of a discharge pipe formed in a single pipe or a plurality of pipes forming a reinforcing pipe. By providing a projecting portion protruding outward from the tube integrally with the tube, the discharge hole and the hole wall of the drilling hole are prevented from closely contacting each other, and the discharge hole is less likely to become clogged. The function is maintained without invalidating the discharge holes, and there is an effect of improving the adhesion resistance by the above-described protrusions compensating for the lack of the adhesion force of the peripheral surface due to the conventional steel pipe having a smooth peripheral surface.

  Further, the vertical slit reduces the escape of the consolidated material from the effect of dispersing the discharge of the consolidated material, and the fixing and improving region by the uniform consolidated material is easily formed over the entire length around the reinforcing tube, and the adhesion is improved. Has the effect of improving proof stress. For the extruding behavior from the ground in front of the face, which is the release stress during tunnel excavation, the strength of the material is fully exerted by the cement or resin-based solidified material, and the ground restraint effect around the reinforcing pipe is obtained . Moreover, exfoliation of the crest of the top end caused by insufficient fixation around the reinforcement pipe and the pushing-out behavior of the mirror part are suppressed, and a highly uniform injection reinforcement effect is exhibited and there is no need to perform additional reinforcement during tunnel excavation work. As a result, the correspondence of the natural ground spreads and a suitable natural ground reinforcing effect can be obtained. In addition, the amount of work and cost in tunnel excavation can be greatly reduced, and the work period and construction cost for the auxiliary construction method can be suppressed to increase the safety of the work.

  Hereinafter, the ground reinforcement method according to the present invention will be described in detail based on the embodiment shown in the drawings. 1 and 2 show an outline of an embodiment in which the ground reinforcement method according to the present invention is applied to a tunnel receiving work. FIG. 1 (a) is a longitudinal sectional view showing a construction state of the receiving work. (B) is the transverse sectional view, and FIG. 2 is an enlarged longitudinal sectional view of the face portion after the construction of the front receiving work. Members having the same functions as those in FIGS. Thus, duplicate descriptions are omitted or simplified.

  FIG. 1 shows a state in which a receiving work A is being constructed in the vicinity of the top end in front of the tunnel face under construction, and shotcrete 2 is applied to the face 1a of the ground 1 exposed in the previous tunnel excavation work. A support is formed behind the face 1a (left side in the figure) in a state where excavation has already been completed. As support, sprayed concrete 4a is applied to the tunnel space T in the tunnel excavation cross section so as to cover the ground 1 of the side wall and the arch portion, and a steel support 4b is provided inside the tunnel cross section of the tunnel. It is built at predetermined intervals (for example, every 1 m) in the tunnel excavation direction in a shape along the shape.

  Further, at the top end of the tunnel space T in front of the face, the receiving work A, which was constructed prior to the excavation work, is placed in the natural ground 1 so as to form an arch shape at predetermined intervals in the excavation direction and in the circumferential direction. Is formed. The front receiving work A includes a reinforcing pipe 6 serving as a ground reinforcing material placed at a predetermined pitch along the transverse cross-sectional shape of the tunnel and at predetermined intervals in the excavation direction, and an injection pipe (not shown) to the reinforcing pipe. 6 and a bulkhead region 7 improved by a consolidation material injected into the surrounding ground 1. In the present embodiment, the reinforcing pipe 6 is composed of a plurality of front reinforcing pipes 61 and rear reinforcing pipes 62 connected in order by screw joining, and a porous pipe 63 for forming a bulkhead region connected to the rearmost end thereof. It consists of. The reinforcing pipe 6 made of these pipes 61 to 63 is driven at a predetermined elevation angle from the upper outer periphery of the face 1a toward the front ground 1 and is provided in the circumferential direction of the tunnel.

  As shown in FIG. 2, the front receiving work A of the present embodiment is not widened and does not widen the steel support work. Therefore, the rear cutting part A <b> 2 (the main cutting part A <b> 2) corresponds to the length L to be cut during tunnel excavation. In the embodiment, about 4 m) is set. In the present embodiment, the reinforcement pipe 6 constituting the front receiving work A is a front reinforcement pipe 61 made of a steel pipe having a diameter of 76.3 mm and a length of 3 m on the front side (hole back side) A1 from the rear cutout part A2. A plurality of male and female screw joints (three in this embodiment as a predetermined number) are connected, while the rear cutout A2 has a diameter of 76.3 mm and a predetermined unit length of 3 m of a rear reinforcing pipe 62, One porous tube 63 having a diameter of 76.3 mm and a length of 1 m is connected to each one. The diameters and lengths of the pipes 61 to 63 and the number of connections are appropriate, and the reinforcing pipe 6 may be constituted by a single pipe.

  In the present embodiment, a protrusion 6b protruding outward from the pipe is provided integrally with the pipe in the vicinity of the discharge hole 6a formed in the pipe constituting the reinforcing pipe 6. In the present embodiment, FIG. As shown in FIG. 3, a protrusion 6b protruding outward of the reinforcing pipe 62 is covered in the vicinity of the discharge hole 6a provided in the rear reinforcing pipe 62 constituting the reinforcing pipe 6 so as to cover at least a part of the discharge hole 6a. Thus, the reinforcing tube 62 is provided integrally. In the case shown in the drawing, the protruding holes 6a are provided at two diametrical positions at predetermined intervals in the axial direction of the reinforcing tube 62, and the discharge holes adjacent in the axial direction are shifted by about 90 degrees in the circumferential direction. It is the structure provided. In the case of the figure, the protrusion 6b is an angle-shaped metal plate that protrudes outward from the outer peripheral surface of the reinforcing tube 62 in the vicinity of each discharge hole 6a as shown in FIGS. 3 (d) and 3 (e). The protrusion forming member 16 made of, for example, is integrally fixed to the outer peripheral surface of the reinforcing pipe 62 by welding or the like so as to cover almost the entire opening of the discharge hole 6a.

The height of the protrusion 6b from the outer peripheral surface of the reinforcing tube and the location of the protrusion 6b are appropriate. In general, the height of the protrusion 6b is preferably about 3 to 15 mm, and the installation location is a discharge hole. It is preferable that the length of the reinforcing pipe 62 is set to about 2 to 6 locations per meter (about 4 to 12 pieces) along with the length 6a, and designed appropriately in consideration of the degree of increase in adhesion strength.

  The front reinforcing pipe 61 is connected to the front side (right side in FIG. 1) of the rear reinforcing pipe 62 as described above, and the discharge hole 6a and the protruding part are also configured to the front reinforcing pipe 61 with the same configuration as described above. 6b is omitted in the figure. Further, when the porous tube 63 is connected to the rear side (left side in FIG. 1) of the rear reinforcing tube 62 as described above, the above-described protrusion 6b is also provided in the vicinity of the discharge hole 6a of the porous tube 63. You may do it. The discharge hole 6a of the porous tube 63 is formed in the shape of a long hole in the axial direction of the porous tube 63 in the figure, but the shape is appropriate. Moreover, although the discharge hole 6a of the front part reinforcement pipe | tube 61 and the rear part reinforcement pipe | tube 62 was formed circularly in this embodiment, the shape can also be changed suitably.

  The rear reinforcing pipe 62 and the perforated pipe 63 arranged in the rear cutting section A2 are configured so that a portion exposed from the natural ground 1 during tunnel excavation can be easily cut with a drilling machine. As shown in FIG. 3 (a), 360 degree annular grooves 6c are formed in the circumferential direction at predetermined intervals on the outer peripheral surfaces of the rear reinforcing pipe 62 and the porous pipe 63, and between the adjacent annular grooves 6c and 6c. A longitudinal slit (slit hole) 6d capable of discharging a consolidated material extending in the longitudinal direction (axial direction) of the reinforcing pipe is provided so that it can be easily excised by the excavating machine.

The annular groove 6c is formed in the rear reinforcing pipe 62 and the perforated pipe 63 at a predetermined depth leaving a thickness that can be cut by the excavating machine, and at substantially equal intervals in the axial direction. In the rear reinforcing pipe 62, four annular grooves 6c are formed at intervals of about 1 m so as to divide the length into three, and the porous pipe 63 is formed with two annular grooves 6c at intervals of about 1 m. ing. Further, one longitudinal slit 6d is provided between the adjacent annular grooves 6c and 6c, and the three longitudinal slits 6d provided between the four annular grooves 6c and 6c of the rear reinforcing tube 62 are arranged in order. The direction is shifted by 180 degrees. The longitudinal slit 6d may be provided across the threaded portions of the rear reinforcing pipe 62 and the porous pipe 63.

  Although the width and depth of the annular groove 6c are appropriate, for example, the width of the annular groove 6c of the rear reinforcing tube 62 is about 3 to 5 mm, and the depth of the groove is 30 to 30 times the thickness of the rear reinforcing tube made of a steel pipe. About 50% is preferable. In this way, the annular groove 6c of the rear reinforcing pipe 62 is formed by leaving the remaining thickness of the pipe that can withstand the required bending stress during tunnel excavation, thereby ensuring the bending rigidity necessary for the reinforcing pipe and using the excavating machine. Cutting can be facilitated. Moreover, it is good also as a structure which replaced with the circumferential groove | channel 6c of 360 degree | times in the circumferential direction, and provided the pair of semicircular arc-shaped semi-annular groove | channels about 180 degree | times in the circumferential direction in the position about 100-200 mm. The width of the longitudinal slit 6d may be about 1 to 2 mm, and the position of the longitudinal slit 6d is adjacent to the longitudinal slits 6d and 6d with the annular groove 6c interposed therebetween as shown in FIGS. It is desirable that the longitudinal slits 6d and 6d are continuously connected in a straight line so that the fragile portion due to the slit 6d does not concentrate at one place in the circumferential direction by shifting the phase in the circumferential direction.

  For example, the following procedure may be used to construct the advance receiving work A as shown in FIGS. 1 and 2 using the reinforcing pipe 6 configured as described above. First, in the same manner as described above, for example, by a double-pipe type drilling device having a hollow tubular drilling rod (not shown) having a drilling bit at the tip and a reinforcing pipe 6 disposed around the hollow rod. In addition, a hole h is formed in the top end portion in front of the face at a predetermined elevation angle, and at the same time, the reinforcing pipes 6 are sequentially drawn into the hole h and accommodated. FIG. 4A shows the front reinforcing tube 61, the rear reinforcing tube 62, and the porous tube 63, which are omitted in the drawing, being accommodated in the hole h while being sequentially connected by screw joints, and the hole rod is pulled out and removed. Shows the state. It is also possible to employ a drilling method other than the double pipe method.

  When the reinforcing pipe 6 is accommodated in the hole h as described above, the rear end opening of the hole h is sealed with a sealing member 15 such as a waste cloth as shown in FIG. The injection tube 10 or the like is inserted into the reinforcing tube 6 as described above, and the consolidated material is injected into the reinforcing tube 6 and the surrounding natural ground 1. In this embodiment, a pipe made of synthetic resin or the like having a diameter of 30.5 mm and a length of 6 m is used as the injection pipe 10 as shown in FIGS. 5A and 5B. Are provided with a bag packer 11 for forming the bulkhead region 7, a packer tube 11a made of a nylon tube or the like for inflating it, a check valve 11b, an exhaust tube 12, and the like. 13 is a stopper, 14 is an injection valve, and 14a is an injection hose.

  As shown in FIG. 4B, a predetermined amount of urethane chemical solution or the like is injected from the packer tube 11a into the bag packer 11 and the urethane chemical solution or the like is infiltrated into the packer 11 and the surrounding ground 1. Then, the bulkhead region 7 is formed. Next, an injection valve 14 is connected to the injection pipe 10 and cement cement is injected into the reinforcement pipe 6 from the injection hose 14a, so that the discharge hole 6a on the peripheral wall of the reinforcement pipe 6 is inserted into the hole h. After that, the fixing material is infiltrated into the surrounding natural ground 1 to form a fixing or consolidation region 8.

  At that time, even if there is some slime or hole wall collapse in the hole h, or even if the lower part of the reinforcing tube 6 is in close contact with the hole wall of the hole h as shown in FIGS. It will never be. That is, without providing the protrusion 6b as described above in the vicinity of the discharge hole 6a of the reinforcing tube 6 as in the prior art, the discharge hole 6a is simply provided as shown in FIGS. Since the bottom of the reinforcing tube 6 is pressed against the hole h by its own weight and the discharge hole 6a at the bottom is blocked, there is some slime or hole wall collapse in the hole h, or the discharge hole 6a Even if the lower portion of the reinforcing pipe 6 that is opened is only lightly in close contact with the hole wall of the hole h, the discharge hole 6a is blocked, making it difficult for the consolidated material to flow out. 6 (a) and 6 (b), there is a protrusion 6b in the vicinity thereof, so that the discharge hole 6a is not directly in close contact with the hole wall of the drilling hole h and closed, and the lower part of a normal reinforcing pipe In this case, the ineffective discharge hole 6a functions effectively, and the consolidated material is put into the hole h around the reinforcing pipe 6 and its Can be satisfactorily flows out into the natural ground 1 in circumference. As a result, not only the upper portion of the reinforcing tube 6 but also the lower portion of the reinforcing tube 6 can be well discharged, and the consolidated region 8 can be uniformly formed on the entire circumference of the reinforcing tube 6 in the circumferential direction. Thereby, the fixing property and adhesion strength of the reinforcing pipe 6 can be improved.

  The bulkhead region 7 is not necessarily provided. However, if the bulkhead region 7 is formed on the face 1a side, that is, on the opening side of the drilling hole h before the consolidation region 8 is formed, for example, cutting is performed. Even when the natural ground 1 is rough due to the hole h or when cracks or voids are formed in the surrounding natural ground 1, the cement-based solidified material is brittle through the cracks or voids. There is an advantage that it can be prevented from overflowing to the 1a side.

  The tip receiving work A formed as described above is formed in an arch shape in the vicinity of the top end in front of the face 1a as described above. In this state, the tunnel excavation work is carried out by an excavator or the like. At that time, as shown in FIG. 4 (c), the reinforcement pipes in the excavation region by the excavator, that is, the rear reinforcement pipe 62 and the perforated pipe 63 are cut by the excavator, and the rear reinforcement pipe 62 and In the present embodiment, since the annular groove 6c and the longitudinal slit 6d are formed in the porous tube 63 as described above, the porous tube 63 can be easily excised with an excavating machine. After that, the construction of the advance receiving work A and the tunnel excavation work are further advanced while the support work 4b is being built in order by the amount of advancement of the face 1a along with the excavation.

  As described above, in the present invention, the pipe protrudes outward in the vicinity of the discharge hole 6a formed in the pipe forming the reinforcing pipe 6 (the front reinforcing pipe 61 and the rear reinforcing pipe 62 in the above embodiment). By providing the protrusion 6b integrally with the pipe, even when the discharge hole 6a is positioned below the reinforcement pipe 6 when the reinforcement pipe 6 is installed in the drilling hole h, the protrusion 6b The discharge hole 6a is not blocked by the wall surface of the hole h and does not become invalid. As a result, the area around the reinforcement pipe 6 is expanded and the ground improvement area is expanded, and the natural ground located on the reinforcement pipe 6 from the outer periphery of the tunnel excavation cross section is also a thin layer of natural conditions where the outer peripheral line of the tunnel excavation is easy to peel off. A fixing region by a caking material is secured at the lower part of the reinforcing pipe 6, and the stability of the top end of the face during tunnel excavation is increased and rational reinforcement is possible.

  In addition, even when a cement-based caulking material is used as the caulking material, the surroundings of the reinforcing pipe 6 can be reliably fixed and the natural ground can be improved. An effective reinforcing effect can be expected because a fixing force and an improved region that can withstand the pushing-out behavior of the face accompanying excavation are secured. Furthermore, in the construction using the long steel pipe tip receiving method as described above, a fixing area is secured by the consolidated material even in fragile ground conditions, and the lack of peripheral surface adhesion due to the steel pipe with a smooth peripheral surface is reinforced. The reinforcing pipe provided with the protrusion 6b in the vicinity of the discharge hole 6a on the outer peripheral surface supplements, and the protrusion 6b and the longitudinal slit can effectively exhibit the adhesion effect. As a result, the axial rigidity and bending rigidity of the reinforcing pipe 6 are appropriately secured, and further, the reinforcing effect by the solidified material to the surrounding natural ground 1 is surely achieved, so that the stability of the natural ground is sufficiently secured. Is done. Therefore, the tunnel excavation work can be performed efficiently and safely.

  The configuration of the protrusion 6b can be changed as appropriate. In the above embodiment, in the vicinity of each discharge hole 6a, the outer periphery of the reinforcing pipe 6 (the front reinforcing pipe 61 and the rear reinforcing pipe 62 in the above embodiment). A protrusion forming member made of an angle-shaped metal plate or the like protruding outward from the surface is integrally fixed to the outer peripheral surface of the reinforcing tube 62 by welding or the like. For example, FIG. As shown in b), a folded overlap portion 16a that protrudes further outward may be provided at a corner portion of the protrusion forming member 16 made of the above-described angle-shaped metal plate or the like. Alternatively, the protrusion forming member 16 made of the metal plate or the like may be formed in a substantially semicircular shape as shown in FIGS. 7C and 7D. Further, the protruding portion 6b may be formed by projecting a part of the tube in the vicinity of each protruding hole 6a provided in the reinforcing tube 6 (61 to 63) outward from the outer peripheral surface of the tube. FIG. 8 shows an example of this, and a part of the edge of each protrusion hole 6a protrudes outward from the outer peripheral surface of the tube to form a protrusion 6b. Even when the protrusion 6b is changed as described above, the same effect as described above can be obtained.

  Furthermore, although the said embodiment demonstrated the case where it applied to the advance receiving work A as an example, it can also be applied to the mirror reinforcement work B as shown in FIG. Also in this case, a protrusion 6b protruding outward from the pipe is provided in the vicinity of the discharge hole 6a formed in the pipe forming the reinforcing pipe 6, and the front reinforcing pipe 61 is provided in the rear part. It is preferable that the reinforcing tube 62 has a configuration that can be easily excised with an excavating machine such as an annular groove 6c and a longitudinal slit 6d. By using the reinforcing pipe having the projection 6b as described above, the same effect as that of the receiving work A can be obtained, and at the time of tunnel excavation, the reinforcing pipe 6 constructed on the mirror part is provided over the entire length of the excavating machine. Can be easily excised.

  In each of the above embodiments, the bulkhead region 7 is formed by connecting the porous tube 63 to the rear end side of the reinforcing tube 6, that is, the face 1 a side. However, the bulkhead region 7 is constructed without forming such a region. In such a case, instead of using the porous tube 63 as described above, the rear end of the reinforcing tube 6 may be a tube that can be easily excised with the same excavating machine as the rear reinforcing tube 62. That's fine. Further, the reinforcing pipe 6 is formed by connecting a plurality of pipes in each of the above embodiments, but may be formed by a single pipe.

  3 using the reinforcing tube 6 having the protrusion 6b shown in FIG. 3 and the reinforcing tube 6 having the protrusion 6b shown in FIGS. 7 (a) and 7 (b) and FIGS. 7 (c) and 7 (d). 1 and FIG. 2 are actually constructed, and as a comparative example, except that the outer peripheral surface is smooth, a similar receiver A is constructed using the same reinforcing pipe. In order to examine the adhesion force of the reinforcing tube 6 to the hole wall of the drilled hole h and the ground 1, an effectiveness adhesion test was performed. The results are summarized in Table 1 below.

Note that the angle shape (1) in Table 1 above is obtained when the reinforcing pipe 6 having the protrusion 6b shown in FIG. 3 is used, and the angle shape (2) is shown in FIGS. 7 (a) and (b). When the reinforcing tube 6 having the protruding portion 6b shown is used, the semicircular shape is the case where the reinforcing tube 6 having the protruding portion 6b shown in FIGS. 7C and 7D is used. The uniaxial compressive strength in the table is the compressive strength (load resistance) when the mortar used in this test was compressed from one direction after 24 hours using a cylindrical specimen having a diameter of 5 cm and a height of 10 cm. Is the adhesion force (tensile load resistance) per unit area (1 mm ² ) of the cement-based solidified material adhering to the reinforcement pipe 6 as the adhesion force of the respective reinforcement pipes 6 to the hole wall at the age of 24 hours. The adhesion force per meter is a value obtained by dividing the pull-out load of the reinforcing tube 6 constructed in the hole h by the length of the reinforcing tube 6.

  As is clear from Table 1 above, the ground reinforcement method according to the present invention, that is, in the vicinity of the discharge hole 6a formed in a single tube or a plurality of tubes forming the reinforcing tube 6, protrudes outward from the tube. The protrusion 6b provided integrally with the pipe is more adhesive than the conventional pipe having a smooth outer peripheral surface provided with the discharge hole 6a, particularly the adhesive force per unit length of the reinforcing pipe 6 ( (Pullout load) can be greatly increased. In addition, when the reinforcing pipe 6 having the protrusion 6b as shown in FIG. 8 is used, the same adhesion force as described above can be obtained, and when applied to the mirror reinforcing work B as shown in FIG. Almost the same result was obtained.

  As mentioned above, in long steel pipe tip receiving work and long mirror reinforcement work, the adhesion strength of the consolidated area formed around the reinforcing pipe is weak material age during tunnel excavation due to the construction cycle. The surrounding surface of the reinforcing pipe is smooth, and if there is an unfixed area of the consolidated material and insufficient improvement around the steel pipe, the restraint force of the natural ground is impaired, and the gradual increase behavior of peeling or loosening is likely to occur. In the situation where the hole wall is not self-supporting in a fragile ground where the area where the position is located, even if the hole wall collapses around the reinforcing pipe or the lower end of the reinforcing pipe is in close contact with the hole wall, the entire area around the reinforcing pipe is covered. Further, it is characterized in that a solidified region by a cemented material or a resin-based solidified material is ensured, and the natural ground around the hole wall and the peripheral surface shape of the reinforcing pipe have a large adhesion strength.

  By providing the protrusion 6b in the vicinity of the discharge hole 6a on the peripheral wall of the reinforcing pipe in which a single pipe or a plurality of pipes are sequentially connected as described above, the adhesion strength between the fixing material and the steel pipe is improved. Close to the wall is avoided and clogging of the discharge hole is difficult to occur, and the function of the discharge hole is exhibited without invalidating the injection effect even at the lower part of the reinforcing pipe, and only a limited discharge hole is formed in the longitudinal direction. Instead, the effect of dispersing the discharge reduces the escape of the injected material and facilitates the discharge to the steel pipe peripheral surface. It is easy to form a fixed and improved region with uniform injection material over the entire length of the periphery of the reinforcing pipe, and a thin layer of natural ground that is easily peeled off from the reinforcing pipe to the outer circumference of the tunnel excavation section in the receiving work The increase increases the restraint during tunnel excavation. In addition, the increase in the adhesion strength of the reinforcing pipe in the long mirror reinforcing work suppresses the preceding displacement accompanying the pushing-out behavior of the mirror part, and the face situation can be stably and rationally reinforced.

  As described above, according to the natural ground reinforcement method according to the present invention, the protrusion 6b is provided in the vicinity of the discharge hole 6a formed in the reinforcing pipe 6, thereby avoiding the close contact between the hole wall of the hole h and the discharge hole 6a. The discharge hole 6a is less likely to become clogged, the discharge hole in the lower part of the reinforcing pipe functions without being invalidated, and the lack of peripheral surface adhesion due to the steel pipe having a smooth peripheral surface improves the adhesion strength by the protrusion 6b. There is an effect to make. In addition, the longitudinal slit perpendicular to the annular groove reduces the escape of the injection material from the effect of dispersing the discharge of the injection material, and it is easy to form a fixing and improvement region by the uniform injection material over the entire length around the reinforcing tube, It has the effect of improving adhesion strength. For the extrusion behavior, which is the release stress during tunnel excavation, the strength of the material is fully exerted by the injection material such as cement or resin, and the effect of restraining the surrounding wall of the reinforcing pipe is obtained. In addition, the exfoliation caused by insufficient fixation around the reinforcement pipe and the extrusion behavior of the mirror part are suppressed, exhibiting a highly uniform injection reinforcement effect and no need for additional reinforcement during tunnel excavation work. Correspondence spreads and a suitable ground reinforcement effect can be obtained. In addition, the amount of work and cost in tunnel excavation can be greatly reduced, and the work period and construction cost for the auxiliary construction method can be suppressed to increase the safety of the work.

(A) is the longitudinal cross-sectional view of embodiment which applied this invention to the tunnel tip receiving work, (b) is the cross-sectional view. The expanded longitudinal cross-sectional view of the face part of the state which constructed the said prior work. (A) is a side view of a part of the reinforcing pipe used in the above embodiment, (b) is a partly enlarged view, (c) is a partly enlarged view, and (d) is a partly perspective view. The figure, (e) is ee sectional drawing in (c). (A)-(c) is explanatory drawing which shows an example of the construction process of a receiving work. (A) is a side view of a state where an injection tube or the like is mounted on the reinforcing tube, and (b) is a side view of the injection tube or the like. (A) is a side view of the state in which the consolidated material is flowing out from the reinforcing pipe into the surrounding natural ground, (b) is a cross-sectional view taken along the line bb in (a), and (c) is the conventional reinforcing pipe The side view of the state in which the consolidated material has flowed into the surrounding natural ground, (d) is a dd sectional view in (c). (A) And (b) is a cross-sectional view and a partial perspective view showing a modified example of the reinforcing pipe, (c) and (d) are a cross-sectional view and a partial perspective view showing another modified example of the reinforcing pipe. Figure. (A) And (b) is a cross-sectional view and a partial perspective view showing still another modified example of the reinforcing pipe. (A) is the longitudinal cross-sectional view of embodiment which applied this invention to the mirror reinforcement work, (b) is the cross-sectional view. (A) is the longitudinal cross-sectional view which shows the construction state of the tip receiving work by the non-widening of the conventional natural ground reinforcement method, (b) is the cross-sectional view. The longitudinal cross-sectional view which shows the injection | pouring state of a solidification material by the conventional natural ground reinforcement construction method. Explanatory drawing which shows the behavior around the face obtained from an analytical viewpoint. The longitudinal cross-sectional view which shows the form of the tip receiving work by the conventional natural ground reinforcement construction method. The longitudinal cross-sectional view which shows the form of the mirror reinforcement construction by the conventional natural ground reinforcement construction method.

Explanation of symbols

A Ahead work A1 Front side (hole back side)
A2 Rear resection part B Mirror reinforcement
T Tunnel space h Drilling hole 1 Ground 1a Face 2 Mirror part spraying concrete 4a Spraying concrete 4b Steel support
6 Reinforcement pipe 6a Hole back side 6b Rear end 6c Discharge hole 6d Concave groove 6e Annular groove 6f Slit 6g Projection 61 Front reinforcement pipe 62 Rear reinforcement pipe 63 Rear end pipe 7 Bulkhead area 8 Consolidation area 9 Rock drill (Drill jumbo)
9a Guide shell 10 Injection pipe 11 Bag packer 11a Packer tube 11b Check valve 12 Exhaust tube 13 Stopper (rubber plug)
14 Injection valve 14a Injection hose 15 Seal member 16 Projection forming member

Claims (5)

Reinforcing pipe formed by drilling a hole at a predetermined elevation from the tunnel excavation cross section at a predetermined elevation angle and simultaneously connecting a single pipe or a plurality of pipes having a discharge hole for a consolidated material on the peripheral wall. In the ground reinforcement method, in which a consolidation material is injected into the reinforcement pipe and a fixing material is injected into the reinforcement pipe to form a fixing or consolidation area in the surrounding ground. in the vicinity of the discharge hole formed in the tube of a single tube or a plurality of forming a tube, only setting a protrusion that protrudes outwardly above tube integrally tube, the tube in the vicinity of the discharge hole one A ground reinforcement method characterized in that the protrusion is formed integrally with the pipe by projecting the part outward of the pipe . Reinforcing pipe formed by drilling a hole at a predetermined elevation from the tunnel excavation cross section at a predetermined elevation angle and simultaneously connecting a single pipe or a plurality of pipes having a discharge hole for a consolidated material on the peripheral wall. In the ground reinforcement method, in which a consolidation material is injected into the reinforcement pipe and a fixing material is injected into the reinforcement pipe to form a fixing or consolidation area in the surrounding ground. A single tube that forms the reinforcing tube by providing a protruding portion that protrudes outward of the tube integrally with the tube in the vicinity of the discharge hole formed in a single tube or a plurality of tubes forming the tube Alternatively, at least the rear ends of the plurality of pipes are provided with an annular groove having a thickness that can be cut by a tunnel excavating machine, and a longitudinal slit that extends in the longitudinal direction of the reinforcing pipe and that can discharge the consolidated material. A natural ground reinforcement method characterized by having been established. At least the rear end of a single pipe or a plurality of pipes forming the reinforcing pipe, an annular groove having a thickness that can be cut by a tunnel excavating machine, and extending in the longitudinal direction of the reinforcing pipe and The ground reinforcement method according to claim 1, further comprising a longitudinal slit through which the binder can be discharged. 3. The natural ground reinforcement method according to claim 2 , wherein a member projecting outward of the pipe is integrally fixed to the outer peripheral surface of the pipe by welding or the like in the vicinity of the discharge hole to form the protrusion.   Each of the single tube or the plurality of tubes forming the reinforcing tube has an outer diameter of 60 to 139 mm and a length of 1 to 6 m, and is formed by connecting the plurality of tubes. 5. The ground reinforcement method according to claim 1, wherein the total length of the reinforcing pipe is within a range of 3 to 30 m.

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