JP2020084474A - Widening construction method of existing tunnel - Google Patents

Abstract

To provide a widening construction method of an existing tunnel for making it possible to execute a drilling construction to a lining construction on the widening part quickly and safely without performing traffic interruption in the widening construction of a cross section of the existing tunnel.SOLUTION: A side tunnel is constructed in the natural ground adjacent to an outer surface of a side wall of the existing tunnel, and a leg support structure is constructed to support a tunnel lining member of a widening tunnel in the side tunnel. An drilling work platform 44 having a frame surrounding the outer circumference of the existing tunnel is provided so that the legs are located inside the side tunnel. From the drilling work platform 44, a predetermined area of the outer peripheral natural ground of the existing tunnel is ring-cut to form a widened tunnel cross section. A precast concrete lining plate 40 that covers the inner surface of the cross section of the widening tunnel is sequentially loaded and assembled to support the upper half portion of the widening tunnel. The lining of the existing tunnel is crushed by using a working machine that can run on the protector in the existing tunnel to complete the widening tunnel cross section.SELECTED DRAWING: Figure 6

Description

The present invention relates to a widening method for an existing tunnel, and particularly in a construction for constructing a rehabilitated tunnel by widening a tunnel section of an existing tunnel, it is possible to quickly and safely excavate a widened portion without blocking traffic during construction. This is related to the widening method of an existing tunnel that enables even lining work.

In order to cope with the addition of sidewalks and the increase in size of vehicles passing through the road tunnel, it is possible to construct a new tunnel by providing a route close to the road tunnel, but the extension of the tunnel becomes longer and the approach is approached. It is difficult to realize because of problems such as land problems including roads. Therefore, there is a high possibility that a countermeasure for constructing a rehabilitated tunnel in which the cross section of a conventional existing tunnel is widened is highly feasible, and various studies have been made. An important issue at this time is to proceed with the construction of the rehabilitation tunnel without blocking the traffic of the existing tunnel as much as possible. Therefore, various tunnel widening methods have been proposed for rapidly widening the cross section of the existing tunnel in a state where the existing tunnel is used, that is, under a so-called live line (Non-Patent Document 1).

Among various widening methods introduced in Non-Patent Document 1, a widening method that can secure the traffic volume of the existing tunnel (two-lane traffic) and can minimize excavation of the ground around the existing tunnel. As an example, the arch cut method and the side wall mine leading both sides expansion method are shown.

In the arch cut method, the lining concrete of the existing tunnel is used as a protector, and a series of work from excavation to support and lining dismantling is performed by a multifunctional special machine equipped to be supported by this protector. ..

In the method of expanding both sides of the side wall mine, it is assumed that the lining concrete will be used as a work platform for expanding and excavating the tunnel, and that it will also be used as the gantry of the lining for lining.

Toshiaki Ishimura, "Enlargement of Section of Existing Tunnel", Construction Machinery, Nippon Kogyo Publishing, December 1, 2004, Volume 40, No. 12, p. 8-13, <URL: http://www.nikko-pb.co.jp/photos/logmok/c_0412.pdf>

In any of the above-mentioned widening methods for existing tunnels, a large protector that can run in the tunnel and has an upper gantry on which a construction vehicle can run or a continuous belt conveyor can be installed is installed. There is a problem that large-scale temporary equipment is installed, such as continuous discharge of scraps (excavated soil) with a belt conveyor, etc., and the construction cost of excavation work increases. In addition, in each widening method, the lining construction is performed by using cast-in-place concrete by incorporating a centle for the lining concrete in the rear part of the large protector. For this reason, shortening the construction period for lining concrete work is also an issue.

Among them, in the arch cut method, it is necessary to equip a special dedicated machine that travels along an arch frame that follows the outer shape of the lining concrete of the existing tunnel, and there is a problem that the cost of machinery and equipment increases. In addition, since the excavation gap is carried out in the traveling direction by the dump truck that travels through the tunnel that has been penetrated in advance, it is necessary to previously excavate the tunnel with a cross section through which the dump truck can pass over the entire length. .. Therefore, there is also a problem that the construction period of the tunnel construction becomes long.

In the method of expanding both sides of the side wall guideway, as described above, the work platform used for tunnel excavation is equipped with not only a free-section excavator but also a rock bolt placing device, etc. Since it is also used as a gantry for construction, it is necessary to equip it with a solid gate frame. In addition, it is necessary to remodel the gantry in order to mount a centle for lining concrete construction on this portal frame. Further, since the excavation scrap is carried out in the traveling direction by the dump truck that travels through the guide hole that has been penetrated in advance, there is a problem similar to the arch cut method.

The object of the present invention is to solve the above-mentioned problems of the conventional technology, and in the construction for expanding the existing tunnel, it is leased in the market without interrupting conventional traffic, and is relatively inexpensive and easy to introduce. The existing tunnel is excavated using the construction machine to the minimum extent, and the excavation is carried out by the traveling carriage that rail-travels inside the side tunnel to be translated, and the excavation is performed as the lining of the excavated new tunnel. It is to provide a widening method for existing tunnels that enables rapid and stable construction of widening tunnels by sequentially installing precast concrete lining plates in parallel with the progress.

In order to achieve the above object, the method for widening an existing tunnel of the present invention is to construct a side tunnel over the extension of the existing tunnel in the ground adjacent to the side wall outer surfaces on both sides of the lining concrete of the existing tunnel. In the side tunnel, over the extension of the existing tunnel, construct a leg support structure that supports the leg of the tunnel lining member of the widening tunnel at the top, and on the traveling rail laid in the side tunnel, the An excavation work platform having a frame structure surrounding the outer circumference of the lining concrete of the existing tunnel is provided, the excavation work platform is run along the existing tunnel, and the outer circumference of the existing tunnel is placed on the excavation work platform. Forming a widened tunnel section by ring cutting a predetermined area of the ground, the legs are supported by the leg support structure, and the precast concrete lining plate covering the inner surface of the widened tunnel section is widened. In order to support the upper half of the widened tunnel by sequentially loading and assembling it into the tunnel part, and using a working machine capable of traveling on the protector provided in the existing tunnel, the lining concrete of the existing tunnel is used. Is crushed and carried out to the outside of the mine, and the tunnel cross section after the widening is completed.

In the same construction method, it is preferable to excavate the side tunnel after performing rock bolt support work on the outer peripheral ground of the lining concrete of the existing tunnel to reach the natural rock range that can support the tunnel cross section after widening. ..

It is preferable that the side tunnels are supported by rock bolts and shotcrete that are cast toward the surrounding ground.

It is preferable that a part of the excavation work platform is an arch-shaped frame that follows the outer peripheral shape of the lining concrete of the existing tunnel.

It is preferable that the widened tunnel is supported by a rock bolt and a shotcrete in which a head portion of the rock bolt, which is partially cut and removed by a ring cut, is fixed again.

It is preferable that a connection shaft is provided between the existing tunnel and the side tunnel at a predetermined interval in the tunnel extension direction.

It is preferable that the excavated scrap and the crushed lump of the lining concrete are carried out of the tunnel mine by a vehicle traveling by a rail system.

It is preferable that two-lane traffic in the existing tunnel is maintained until the precast concrete lining plate is installed, and the crushing work of the lining concrete in the existing tunnel is one-lane traffic on one side in the existing tunnel.

The widened tunnel may be supported by a composite lining structure composed of the precast concrete lining plate, the mortar filled between the precast concrete lining plate and the shotcrete, and the shotcrete. preferable.

The schematic front view which showed the cross-sectional shape of the existing tunnel which applies the widening method of the existing tunnel of this invention. The tunnel sectional view (step 1) which showed the construction state of the widening construction of the existing tunnel by one Embodiment of this invention. FIG. 2 is a tunnel cross-sectional view showing the construction status of the widening construction of the existing tunnel according to the embodiment of the present invention (step 2). The tunnel sectional view showing the construction situation of the widening construction of the existing tunnel by one embodiment of the present invention (Step 3). FIG. 6 is a vertical cross-sectional view showing an arrangement example of construction machines for widening the existing tunnel shown in FIG. 5. The tunnel sectional view which showed the construction condition of the widening construction of the existing tunnel by one Embodiment of this invention (step 4). The tunnel sectional view showing the construction situation of widening construction of the existing tunnel by one embodiment of the present invention (Step 5). The tunnel sectional view showing the construction situation of widening construction of the existing tunnel by one embodiment of the present invention (Step 6). The tunnel sectional view which showed the service condition of the widening tunnel completed by the widening construction of the existing tunnel of this invention.

Hereinafter, the following construction examples will be described with reference to the accompanying drawings as modes for carrying out the method for expanding an existing tunnel according to the present invention.

FIG. 1 shows an example of the cross-sectional shape of an existing tunnel 50 that is the target of widening work. The existing tunnel 50 shown in FIG. 1 is a two-lane road tunnel without a sidewalk having a road width of about 3.00 m. The radius of the upper half arch portion 51 is about 4.2 m, and as shown by the building limit 52, it has an internal cross section that allows the roadway width to be minimized. Needless to say, the above numerical values are only examples of construction and are not limited numerical values.

Hereinafter, a series of construction conditions (steps 1 to 7) of the existing tunnel widening method according to the embodiment of the present invention will be described with reference to FIGS. 2 to 9.

FIG. 2 shows a tunnel cross-section showing a construction situation (step 1) in which the rock bolt 21 is driven from the upper half arch portion 51 of the existing tunnel 50 to the surrounding ground and a state in which the lock bolt 21 is driven. .. The construction of the lock bolt 21 is performed as a night work in which the one-sided alternate traffic regulation is performed as shown in FIG. As a construction vehicle, a tire-type 2 boom drill jumbo 22 capable of driving a self-drilling rock bolt 21 is provided, and locks on the ground around the upper half arch portion 51 from the mount 22A of the jumbo 22 located in the upper and lower lanes. The bolts 21 are driven radially. In the present embodiment, some of the bolts are cut and removed by natural rock excavation at the time of widening the tunnel. Therefore, the rock bolt 21 has a predetermined strength and can be easily cut by excavation or the like as the solid glass fiber reinforced plastic. A lock bolt 21 made of steel is placed. In addition, it is important to set the bolt length to a length that can support the loosened area of the ground around the expected widened tunnel. After placing the lock bolt, high-strength mortar (not shown) is injected over the entire length of the lock bolt hole to secure the support of the ground around the tunnel during and after the widening.

FIG. 3 shows a construction situation in which the side tunnel 10 is excavated in the ground on both sides of the leg portion of the existing tunnel (the left side tunnel 10 in the figure), and a construction situation in which the abutment 15 as a leg support structure is constructed ( The tunnel section which showed the construction state of each process (step 2) of the right side tunnel 10) in the figure is shown. The construction of this side tunnel 10 is performed by NATM, and the excavator 17 with a pile stacking conveyor is used for excavation. In order to perform various excavation work by one unit, buckets, twin headers, breakers, nibblers, etc. The attachment can be used by changing the attachment. The excavation of the side tunnel 10 is performed prior to the upper half ring cut work for widening described later, but it is not necessary to excavate the entire tunnel extension in advance, and the translation work is performed prior to the upper half ring cut work. You can also

In the present embodiment, a rail-type battery locomotive and a steel wheel (not shown) are provided for slipping out work. Small-sized locomotives that run on the rail system do not need exhaust ventilation because they do not emit exhaust gas, and have the advantage that the tunnel section can be made smaller than the tire system.

Steel support structure 11 (H-100×100) was built at a 1.2 m pitch as a support structure for the side tunnel 10, and arches and sidewalls were sprayed with concrete 12 (for example, spraying thickness 5 cm) and widened in the same manner as the existing tunnel. A solid type glass fiber reinforced plastic lock bolt 13G is supported in the range to be used, and a steel lock bolt 13S is used in the other range.

Further, in the present invention, the connecting holes 18 are provided between the existing tunnel and the side tunnel 10 at a pitch of about 30 m in the tunnel extension direction. This connecting shaft 18 can be used as a work connecting passage or an evacuation route after that. The cross section of the general connecting shaft 18 is such that workers can pass through it, but at several places, small heavy equipment can pass or excavation scraps from the existing tunnel side to the side tunnel side, and work to carry out concrete crushed lumps, etc. It is preferable to ensure a cross section.

Further, an abut 15 for a new tunnel is built in the side tunnel 10. In the present invention, the abutment 15 is a slab 16S capable of traveling on a work platform, which will be described later, and the slab 16S, which is integrally constructed with a wall body that supports the legs of the precast concrete lining plate 40 (FIG. 6) at the top surface thereof. It has a substantially L-shape composed of the portion 16A. To construct the abutment 15, a movable formwork (not shown) having a predetermined length in the tunnel longitudinal direction is used, and the waterproof structure 14 is applied between the supporting structure of the side tunnel 10 and the wall. The body portion 16A and the slab plate 16S are integrally reinforced (not shown), a formwork capable of simultaneously constructing both portions is set, and concrete placing is performed. In concrete placing work, continuous placing is performed by a concrete pump using an agitator car that can run in the side tunnel 10. Since the wall portion 16A is a heavy structure having a width of about 1.2 m, it sufficiently resists the lateral pressure from the surrounding ground that may occur when the tunnel is expanded, and the slab plate 16S and the side swelling in the side tunnel are prevented. It can also play a role such as prevention. When the ground condition of the surrounding ground is good, the slab 16S may be omitted and only the wall portion 16A may have a self-standing abut shape.

FIG. 4 shows a tunnel cross section showing a construction state (step 3) of the upper half ring cut by NATM for excavating the surrounding ground 53 of the upper half arch portion 52 of the existing tunnel. Due to this upper half ring cut, the ground surface of the excavated tunnel cross section has a shotcrete 32 newly constructed to cover the ground, and the lock bolt 21 with the bolt head re-fixed at the position on the surface. FIG. 5, which is supported by and, is a longitudinal sectional view of a tunnel showing an arrangement example of the construction machine 35 for this upper half ring cutting work.

In this upper half ring cutting work, as shown in FIGS. 4 and 5, a self-propelled excavation work platform 34 is used so as to be located on the peripheral side of the existing tunnel 50, and three units are mounted on this excavation work platform. The excavator 35 (in this embodiment, a backhoe) is mounted on the excavator 35 to excavate the excavator 35 in a shared range.

As shown in FIG. 4, the excavation work platform 34 is a steel frame in which an arch frame 34A having a substantially arcuate shape with a radius larger than the outer shape of the lining of the existing tunnel 50 and a pillar 34C supporting the arch frame 34A are integrated. It is composed of a frame, and traveling wheels W are equipped at the lower ends of the columns 34C. As a result, the work platform 34 can travel on the slab 16S of the abutment 15 or on the ground leveled in the tunnel longitudinal direction. An upper floor 36 located at the top of the arch and an intermediate floor 37 located at both shoulders of the arch frame 34A are installed on the arch frame 34A, and an excavator 35 is provided on each floor 36, 37. Each excavator 35 can perform excavation work by exchanging attachments such as twin headers, breakers, and nibblers according to the ground condition of the excavation target and the excavation application. The excavation scrap is continuously carried out to the outside of the tunnel by a scrap-discharging steel vehicle (not shown) that is provided in the side tunnel 10 and that can travel by rail.

Steel support 32 (H-150×150) is built in the upper half of the new tunnel excavated in a predetermined cross section at a predetermined pitch (for example, 1.2 m pitch) in the tunnel longitudinal direction, and sprayed concrete 31 (for example, sprayed). While the thickness of 10 cm is being applied, the head of the lock bolt 21 is partially re-fixed by excavation of the ground and the end of the bolt is exposed. Moreover, it is preferable to cover the entire surface of the sprayed concrete 31 with a waterproof sheet (not shown) before the precast concrete lining plate 40 (FIG. 6) to be built thereafter is constructed.

FIG. 6 is a tunnel cross-section showing a construction situation (step 4) of installation of a precast concrete lining plate (hereinafter, referred to as PCL plate 40: Precast Concrete Lining plate) that functions as a secondary lining for a new tunnel portion. Shows. Further, the above-described vertical section of FIG. 5 shows the lining plate installation work platform 44 disposed behind the excavation work platform 34. The lining plate installation work pedestal 44 is a steel frame frame composed of an arch frame 44A and a pillar 44C having substantially the same shape as the above-mentioned excavation work pedestal 34, and an erector 45 for installing the lining plate of the PCL plate 40 on the upper floor. Is installed.

As shown in FIG. 6, the PCL plate 40 is composed of a precast concrete member having a two-piece arch shape that is joined at the top of the arch. The PCL plate 40 is mounted on the lining plate installation erector 45 (FIG. 6) on the self-propelled lining plate installation work platform 44 in the temporary assembly yard provided at the tunnel pit as shown in FIG. It is carried into the tunnel. The PCL plate 40 is built and assembled by operating the lining plate installation erector 45.

The leg portion 40a of the arch-shaped PCL plate 40 is supported on the wall portion 16A of the abutment 15 in the side tunnel 10 in which a part of the arch is removed by the ring cut, and stands on its own, but is integral with the shotcrete 31. For this purpose, backfilling injection is performed between the back surface of the PCL plate 40 and the shotcrete 31 with a high-strength mortar 41 (FIG. 7) having a predetermined thickness. In this embodiment, a back-filling lining having a mortar thickness of 30 cm is applied. The size of the PCL plate 40 is set so that the mortar thickness of the backfill lining can be secured. Due to the composite lining structure of the backfill lining made of the PCL plate 40 and the high-strength mortar, the arch part can have a long life.

FIG. 7 shows a tunnel cross section showing a construction state (step 5) of the work for removing the lining of the existing tunnel. Only when removing the lining of this existing tunnel, the self-propelled protector 60 corresponding to one lane is used.

The protector 60 is composed of a frame having rigidity such that the backhoe 61 can operate on the roof floor 60A. A concrete cutter is attached to the attachment of the backhoe 61 deployed on the roof floor 60A, and the arch concrete 54 and the side wall concrete 55 are cut into large pieces into a concrete mass that can be transported from the protector 60 using the concrete cutter. Each concrete block is discharged to the outside of the tunnel mine through the inside tunnel 10. It is preferable that the removal and discharge work should be carried out under a one-lane alternate traffic regulation at night when the traffic volume is low.

FIG. 8 shows a cross section of the tunnel 1 after widening showing the construction status (step 6) of the newly installed roadbed work 65, roadwork 66, and auxiliary equipment 67. After the lining concrete of the existing tunnel over the entire length of the tunnel is completely removed, the central two lanes are opened to traffic, and the widened lanes, shoulders, sidewalks, roadbeds 65, roadwork 66, and drainage gutters of various parts of the inspection road, various electric power lines. Construction of incidental equipment 67 such as equipment is advanced.

FIG. 9 shows the cross-sectional shape of the tunnel 1 after the widening and the tunnel service status. After widening, the tunnel 1 has a vehicle limit 2 in which the lane 3 and the shoulder 4 are significantly widened compared to the existing tunnel 50 (Fig. 1), and the sidewalk 6 with a sufficient width is inspected outside the drain groove 5, inspection. A path 7 is provided.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

1 Tunnels after widening 2, 52 Building limit 10 Side tunnels 13G, 13S, 21 Rock bolts 15 Abuts 18 Connecting shafts 11, 31 Sprayed concrete 12, 32 Steel support 34 Excavation work platform 40 Precast concrete lining plate (PCL) Edition)
44 Lining Plate Installation Work Stand 50 Existing Tunnel 52 Upper Half Arch 54 Arch Concrete 55 Sidewall Concrete 60 Protector 65 Roadbed 66 Roadwork

Claims (9)

In the ground adjacent to the side wall outer surface on both sides of the lining concrete of the existing tunnel, build a side tunnel over the extension of the existing tunnel,
In the side tunnel, over the extension of the existing tunnel, construct a leg support structure that supports the leg of the tunnel lining member of the widening tunnel at the top,
An excavation work platform having a frame structure surrounding the outer periphery of the lining concrete of the existing tunnel is provided on a traveling rail laid in the side tunnel, and the excavation work platform travels along the existing tunnel. Then, from the excavation work platform, a predetermined section of the outer peripheral ground of the existing tunnel is ring-cut to form a widened tunnel cross section,
An upper half of the widened tunnel in which the legs are supported by the leg support structure and the precast concrete lining plate covering the inner surface of the widened tunnel cross section is sequentially loaded into the widened tunnel portion and assembled. Support for
Using a working machine capable of traveling on a protector deployed in the existing tunnel, the lining concrete of the existing tunnel is crushed and carried out of the mine,
A method for widening an existing tunnel, characterized in that a section of the tunnel after the widening is completed. 2. The existing tunnel according to claim 1, wherein the side tunnel is excavated after the rock bolt support work that reaches the rock mass range that can support the tunnel cross section after widening is applied to the outer peripheral ground of the lining concrete of the existing tunnel. Tunnel widening method. The method for widening an existing tunnel according to claim 1, wherein the side tunnel is supported by rock bolts and shotcrete that are cast toward the surrounding ground. The method for widening an existing tunnel according to claim 1, wherein the excavation work platform partially includes an arch-shaped frame that follows the outer peripheral shape of the lining concrete of the existing tunnel. The method for widening an existing tunnel according to claim 1, wherein the widened tunnel is supported by a rock bolt and a shotcrete in which a head of the lock bolt, which is partially cut and removed by a ring cut, is fixed again. The widening method for an existing tunnel according to any one of claims 1 to 3, wherein connecting tunnels are provided between the existing tunnel and the side tunnels at predetermined intervals in a tunnel extension direction. The method for widening an existing tunnel according to claim 1, wherein the excavated scrap and the crushed lump of the lining concrete are carried out of the tunnel mine by a vehicle that travels by a rail method. The two-lane traffic in the existing tunnel is maintained until the installation work of the precast concrete lining plate, and the crushing work of the lining concrete in the existing tunnel is one-lane traffic on one side in the existing tunnel. Widening method for the existing tunnel described. The widened tunnel is supported by a composite lining structure composed of the precast concrete lining plate, the mortar filled between the precast concrete lining plate and the shotcrete, and the shotcrete. The method for widening the existing tunnel described in 4.

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