Tunnel lining formwork alignment structure

Abstract

The present invention provides a tunnel lining formwork alignment structure that prevents the upper formwork from colliding with the leading edge portion of the pre-fabricated lining concrete. [Solution] The structure includes a lap bracket member 11 that is joined and fixed to the rear end surface 22c of the upper formwork 22, an air cushion body 12 that, when placed on the lap bracket member 11, allows its upper surface 12a to contact the inner circumferential surface 30b of the upper end of the pre-filled concrete 30 with a contact surface member 13 interposed, and a contact surface member 13 positioned on the upper surface 12a of the air cushion body 12. By expanding and contracting the lifting jack 26 with the air cushion body 12 inflated, the outer circumferential surface 22b of the rear end portion 22a of the upper formwork 22 can be aligned to the same height position as the inner circumferential surface 30b of the upper end portion 30a of the pre-filled concrete 30 via the air cushion body 12 and the contact surface member 13.

Description

Technical Field

[0001] The present invention relates to an alignment structure for a tunnel lining formwork, and more particularly, to an alignment structure for a tunnel lining formwork that enables alignment of the outer peripheral surface of the rear end portion of the upper formwork of the tunnel lining formwork with the height position of the inner peripheral surface of the upper end portion of the front end portion of preceding lining concrete.

Background Art

[0002] For example, in the mountain tunnel construction method, as a method for forming tunnel lining concrete constructed to cover the natural ground on the inner peripheral surface of an excavated tunnel, a construction method using a tunnel lining formwork called a "centering" is commonly adopted (see, for example, Patent Document 1 and Patent Document 2). As shown in, for example, FIG. 9, the tunnel lining formwork 50 extends from the side wall portion 55 to the upper portion of the tunnel 53 along the inner peripheral surface of the tunnel 53, which preferably has a shape including an arch-shaped portion 52 such as a horseshoe shape. In the lining space 61 between the installed tunnel lining formwork 50 and the natural ground covered by the shotcrete 54 on the inner peripheral surface of the tunnel 53, preferably unreinforced concrete is placed and hardened, so that the lining concrete is formed so as to be continuous with the concrete of the invert portion at the bottom of the tunnel.

[0003] Further, as the tunnel lining formwork 50, in addition to an assembly-type tunnel lining formwork called a "detachable centering", a movable tunnel lining formwork called a "slide centering" is known. As the excavation work of the tunnel 53 progresses, the tunnel lining formwork 50 is reinstalled at every predetermined construction span of, for example, about 10.5 m, and the lining concrete for the side portions and upper portion of the tunnel 53 is sequentially placed and formed from the rear to the front in the excavation direction of the tunnel 53 using the tunnel lining formwork 50.

[0004] Then, in order to pour the lining concrete for the sides and top of the tunnel using the tunnel lining formwork 50, for example as shown in Figures 10(a) to (d), concrete is poured from the inspection window 56 provided in the installed tunnel lining formwork 50 to a height range from the side wall portion 55 of the tunnel 53 to the shoulder portion of the arch-shaped portion 52. Concrete 57 is supplied through the inspection window 56, and a vibrator 58 is inserted through the inspection window 56 to pour the concrete 57 while compacting the supplied concrete 57 (see Figures 10(a) to (c)). Subsequently, for the area of ​​the crown portion 59 (see Figure 9) of the tunnel 53, which is a height region where it is difficult to compact concrete 57 with a vibrator 58 while supplying it from the inspection window 56, a pattern is adopted in which concrete is injected by blowing it up from a blow-up inlet 60 provided on the top of the tunnel lining formwork 50, thereby forming the concrete 57 of the crown portion 59 without directly compacting it with a vibrator (see Figure 10(d)). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2001-280094 [Patent Document 2] Japanese Patent Publication No. 2015-67949 [Patent Document 3] Japanese Patent Publication No. 2003-129800 [Patent Document 4] Japanese Patent Publication No. 2003-278496 [Overview of the project] [Problems that the invention aims to solve]

[0006] Furthermore, with a movable tunnel lining formwork called a slide center, for example, the formwork is repositioned on the front portion of the previously formed pre-lining concrete on the face side in the excavation direction, and the lining concrete for subsequent construction spans is formed sequentially. When installing the tunnel lining formwork on the front portion of the pre-lining concrete in the excavation direction, it is necessary to install the formwork with the outer surface of the formwork body, which constitutes the tunnel lining formwork and is positioned along the inner wall surface of the tunnel to form a lining space between it and the inner wall surface, aligned at a height that allows it to be flush with the inner surface of the leading edge portion of the previously formed pre-lining concrete.

[0007] The formwork body for tunnel lining, as described in Patent Document 2, for example, is composed of an upper formwork that forms the lining space above the arch-shaped portion of the tunnel, a pair of side formwork that forms the lining space below the arch-shaped portion and on both sides of the side walls, and a pair of lower end formwork. The upper formwork is supported so as to be able to move up and down in the vertical direction by a plurality of lifting jacks provided on the base of a gantry trolley. In particular, it is difficult to position the outer surface of the upper formwork at the same height as the inner surface of the upper end of the leading edge of the preceding lining concrete so as to be flush and continuous. For example, when raising the upper formwork with the lifting jacks, the corner of the rear end of the upper formwork may inadvertently collide with the edge of the leading edge of the preceding lining concrete, which can easily lead to a decrease in the quality of the preceding lining concrete, for example, by causing cracks or chips in the collided edge (see, for example, the section on the prior art in Patent Documents 3 and 4).

[0008] Therefore, in the tunnel concrete pouring methods described in Patent Documents 3 and 4, for example, the upper surface is positioned so as to be flush with the outer surface of the upper formwork, the lap angle is extended backward from the rear end surface of the upper formwork, and a joint material made of an elastic material is attached to the upper surface of the extended lap angle (see Patent Document 4), or the upper surface is positioned one step lower than the outer surface of the upper formwork, the lap angle is extended backward from the rear end surface of the upper formwork, and a soft elastic body is attached to the upper surface of the extended lap angle together with the joint material (see Patent Document 3), thereby preventing the corner portion of the rear end of the upper formwork from colliding with the edge portion of the leading edge of the preceding lining concrete.

[0009] However, in the tunnel concrete pouring methods described in Patent Documents 3 and 4, the lap angles are positioned such that their upper surfaces are flush with the outer surface of the upper formwork and protrude behind the upper formwork, or so that their upper surfaces are one step lower than the outer surface of the upper formwork and protrude behind the upper formwork. As a result, these lap angles themselves may collide with the edge of the leading edge of the pre-filled concrete lining, potentially causing cracks and other damage. Therefore, there is a need for the development of a technology that, without impairing the function of positioning the outer surface of the upper formwork at the same height as the inner surface of the upper end of the leading edge of the pre-filled concrete lining, can more reliably prevent the protruding members attached to the upper formwork or its rear end surface from colliding with the edge of the leading edge of the pre-filled concrete lining with a simple configuration.

[0010] The present invention aims to provide a tunnel lining formwork alignment structure that, when installing tunnel lining formwork on the front portion of the pre-lining concrete, can more reliably prevent the upper formwork or overhanging members attached to its rear end from colliding with the edge portion of the pre-lining concrete, without impairing the function of positioning the outer surface of the upper formwork at the same height as the inner surface of the upper end portion of the pre-lining concrete, and with a simple configuration. [Means for solving the problem]

[0011] The present invention relates to a tunnel lining formwork alignment structure for mountain tunnel construction, which enables the alignment of the outer circumferential surface of the rear end portion of the upper formwork, which constitutes the formwork body of the tunnel lining formwork, with the height of the inner circumferential surface of the upper end portion of the leading edge portion of the previously formed pre-formed lining concrete when forming lining concrete using a movable tunnel lining formwork. The upper formwork is supported so as to be able to move up and down in the vertical direction by a plurality of lifting jacks provided on the base portion of a gate-type trolley that constitutes the tunnel lining formwork. The alignment structure includes a lap bracket member that is joined and fixed to the rear end surface of the upper formwork, with the circumferential support plate portion having an outer circumferential surface that serves as a cushion base surface, spaced downward from the outer circumferential surface of the upper formwork and extending vertically backward from the rear end surface, and arranged continuously in the circumferential direction along the outer circumferential surface of the upper formwork, and an air supply... The above objective is achieved by providing a tunnel lining formwork alignment structure that includes an air cushion body that, when expanded, takes on a shape comprising an upper surface portion along the inner circumferential surface of the upper end portion of the leading edge of the preceding lining concrete and a lower surface portion along the cushion base surface, so that when placed on the cushion base surface, the upper surface portion can contact the inner circumferential surface of the upper end portion of the leading edge of the preceding lining concrete with a contact surface member interposed between them, and a contact surface member that extends circumferentially along the upper surface portion of the air cushion body and is attached so that its outer circumferential surface is positioned at the same height as the outer circumferential surface of the outer circumferential surface of the upper end portion of the upper formwork, thereby allowing the air cushion body to be expanded to align the outer circumferential surface of the rear end portion of the upper formwork to the same height as the inner circumferential surface of the upper end portion of the leading edge of the preceding lining concrete via the air cushion body and the contact surface member.

[0012] Furthermore, in the alignment structure for tunnel lining formwork of the present invention, a rubber plate made of soft rubber is attached so as to cover the outer circumferential surface of the contact surface member, and it is preferable that the air cushion body can contact the inner circumferential surface of the upper end of the leading edge of the preceding lining concrete with the contact surface member and the rubber plate interposed between them.

[0013] Furthermore, in the alignment structure for tunnel lining formwork of the present invention, it is preferable that the contact surface member attached along the upper surface of the air cushion body is made of rigid urethane.

[0014] Furthermore, it is preferable that the alignment structure for tunnel lining formwork of the present invention includes a first distance sensor attached to the outer circumferential surface of the rear end portion of the upper formwork for measuring the distance to the leading edge surface of the preceding lining concrete, and a second distance sensor attached to the circumferential support plate portion for measuring the distance to the inner circumferential surface of the upper end portion of the leading edge portion of the preceding lining concrete.

[0015] Furthermore, in the alignment structure for tunnel lining formwork of the present invention, it is preferable that a pressure sensor is provided inside the air cushion body. [Effects of the Invention]

[0016] According to the tunnel lining formwork alignment structure of the present invention, when installing the tunnel lining formwork on the front portion of the preceding lining concrete, it is possible to more reliably avoid collisions between the upper formwork and the overhanging members attached to the rear end surface of the upper formwork and the edge portion of the preceding lining concrete, without impairing the function of positioning the outer surface of the upper formwork at the same height as the inner surface of the upper end of the leading edge of the preceding lining concrete, using a simple configuration. [Brief explanation of the drawing]

[0017] [Figure 1] This is an enlarged cross-sectional view of the main part of section A in Figure 5, illustrating a preferred embodiment of the tunnel lining formwork alignment structure of the present invention. [Figure 2] This is a front view of the air cushion body when inflated. [Figure 3] This is a front view of the lap section bracket member. [Figure 4]This is a schematic cross-sectional view illustrating a tunnel lining formwork installed using the alignment structure for a tunnel lining formwork according to a preferred embodiment of the present invention. [Figure 5] This is a schematic longitudinal sectional view illustrating a tunnel lining formwork installed using the alignment structure for a tunnel lining formwork according to a preferred embodiment of the present invention. [Figure 6] (a) to (d) are schematic sectional views of essential parts illustrating the construction procedure for assembling the alignment structure of the tunnel lining formwork. [Figure 7] (a) and (b) are schematic sectional views of essential parts illustrating the alignment state achieved by the alignment structure for a tunnel lining formwork. [Figure 8] This is an explanatory diagram of a system that controls the alignment performed by the alignment structure for a tunnel lining formwork. [Figure 9] This is a schematic cross-sectional view illustrating a state in which the formwork main body of a tunnel lining formwork is installed along the inner peripheral surface of a tunnel in the background art. [Figure 10] (a) to (d) are schematic side views, partially shown as sectional views, illustrating the work procedure of the tunnel lining concrete placing method using a tunnel lining formwork in the background art. [Modes for Carrying Out the Invention]

[0018] The tunnel lining formwork alignment structure 10, shown in Figure 1 and according to a preferred embodiment of the present invention, is a structure adopted for aligning the upper formwork 22, which allows for smooth installation of the tunnel lining formwork 20 when repositioning the tunnel lining formwork 20 to the forward portion of the previously formed pre-lining concrete 30 on the face side in the excavation direction X, and forming the lining concrete for subsequent construction spans. In particular, it is positioned so that the outer peripheral surface 22b of the upper formwork 22 of the formwork body 21 of the tunnel lining formwork 20 is aligned to the same height as the inner peripheral surface 30b of the upper end portion 30a of the pre-lining concrete 30. The alignment structure 10 for tunnel lining formwork in this embodiment ensures that, when installing the tunnel lining formwork 20 on the front portion of the preceding lining concrete 30, the overlapping bracket member 11, which is an overhanging member attached to the upper formwork 22 and its rear end face portion 22c, reliably avoids collision with the edge portion 30a of the leading edge portion 30a of the preceding lining concrete 30, using a simple configuration.

[0019] Furthermore, the alignment structure 10 for the tunnel lining formwork in the embodiment shown in Figure 1 is a structure that, in mountain tunnel construction, when forming lining concrete using a movable tunnel lining formwork 20 as shown in Figures 4 and 5, allows the outer peripheral surface 22b of the rear end portion 22a of the upper formwork 22 that constitutes the formwork body 21 of the tunnel lining formwork 20 to be aligned with the height of the upper end inner peripheral surface 30b of the front end portion 30a of the previously formed pre-lining concrete 30. The upper formwork 22 is supported so as to be able to move up and down in the vertical direction by a plurality of lifting jacks 26 provided on the base portion 20b of the gantry trolley 20a that constitutes the tunnel lining formwork 20.

[0020] As shown in Figure 1, the alignment structure 10 of this embodiment consists of a lap bracket member 11 which is joined and fixed to the rear end face portion 22c of the upper formwork 22, with the circumferential support plate portion 11b having an outer surface, which is the upper surface, which is the outer surface, being the cushion base surface 11c, spaced downward from the outer surface 22b of the upper formwork 22 and extending vertically rearward from the rear end face portion 22c, and which is arranged continuously in the circumferential direction along the outer surface 22b of the upper formwork 22, and when air is supplied and it expands, it is arranged along the upper inner surface 30b of the tip portion 30a of the pre-filled concrete 30 The air cushion body 12 has a shape that includes a surface portion 12a and a lower surface portion 12b along the cushion base surface 11c, so that when placed on the cushion base surface 11c, the upper surface portion 12a can come into contact with the inner circumferential surface 30b of the upper end portion 30a of the pre-filled concrete lining 30 by interposing a contact surface member 13. The air cushion body 12 is attached by extending circumferentially along the upper surface portion 12a of the air cushion body 12, and its upper surface, which is the outer circumferential surface 13a, is positioned at the same height as the upper surface, which is the outer circumferential surface 22b of the upper formwork 22. By inflating the air cushion body 12, the outer circumferential surface 22b of the rear end portion 22a of the upper formwork 22 can be aligned to the same height as the inner circumferential surface 30b of the upper end portion 30a of the pre-filled concrete lining 30 via the air cushion body 12 and the contact surface member 13.

[0021] Furthermore, in this embodiment, a rubber sheet 14 made of soft rubber extending from the rear end surface 22c of the upper formwork 22 is attached so as to cover the outer peripheral surface 13a of the contact surface member 13, and the air cushion body 12 can contact the upper end inner peripheral surface 30b of the tip portion 30a of the pre-filled concrete lining 30 with the contact surface member 13 and the rubber sheet 14 interposed between them.

[0022] In this embodiment, the tunnel lining formwork 20, which is installed inside the tunnel 40 and forms a lining space 27 between itself and the inner wall surface 41 of the tunnel 40, is a known sliding center that can move in the excavation direction X of the tunnel 40, as shown in Figures 4 and 5. Furthermore, the tunnel lining formwork 20 is preferably a long-span center, and has substantially the same configuration as, for example, the tunnel lining formwork described in Japanese Patent Application Publication No. 2015-67949.

[0023] In other words, the tunnel lining formwork 20 is composed of a gantry trolley 20a formed by connecting and integrating a plurality of gantry frames in the excavation direction X of the tunnel 40, and a formwork body 21 which is supported by the gantry trolley 20a and arranged along the inner wall surface 41 of the tunnel 40, which is covered by, for example, a primary lining made of sprayed concrete, to form the inner formwork surface of the lining space 27. The gantry trolley 20a is equipped with a base portion 20b which serves as a work platform and support legs 20c which consist of a plurality of gantry frames that support the base portion 20b. The lower ends of the support legs 20c are provided with running parts 20d which can travel along rails laid on the floor surface of the tunnel 40, thereby enabling the tunnel lining formwork 20 to move in the excavation direction X of the tunnel 40.

[0024] The formwork body 21 is assembled to have a shape that conforms to the inner wall surface 41 of the tunnel 40 covered by the primary lining (see Figure 4), and is positioned at a predetermined distance from the inner wall surface 41 of the tunnel 40 to form a lining space 27 of a predetermined thickness. The formwork body 21 also includes an upper formwork 22 that forms the lining space 27 above the arch-shaped portion 40a of the tunnel 40, a pair of side formworks 23 that form the lining space 27 below the arch-shaped portion 40a and on both sides of the side wall portions 40b, and a pair of lower end formworks 24. The upper formwork 22 is supported so as to be able to move up and down in the vertical direction by a plurality of lifting jacks 26 provided on the base portion 20b of the gantry trolley 20a. The pair of side formworks 23 are rotatably connected to the lower ends on both sides of the upper formwork 22, and the pair of lower end formworks 24 are rotatably connected to the lower ends of each of the side formworks 23. The side formwork 23 and the lower end formwork 24 are connected to the other end of telescopic jacks 23a and 24a, one end of which is connected to the support leg 20c of the gantry trolley 20a. By extending and retracting these telescopic jacks 23a and 24a, the side formwork 23 and the lower end formwork 24 can be rotated relative to the upper formwork 22 and the side formwork 23.

[0025] These features allow the tunnel lining formwork 20 to be deployed or folded inward by extending or retracting the lifting jacks 26 and telescopic jacks 23a and 24a, enabling the formwork body 21 to be assembled along the inner wall surface 41 of the tunnel 40, or to be moved in the excavation direction X inside the tunnel 40 after the formwork body 21 has been demolded.

[0026] In this embodiment, the alignment structure 10 for the tunnel lining formwork is a structure that allows the outer circumferential surface 22b of the rear end portion 22a of the upper formwork body 21 to be aligned with the height of the inner circumferential surface 30b of the upper end portion 30a of the previously formed pre-lining concrete 30, for example, in portion A of Figure 5. As shown in Figure 1, it is composed of a lap bracket member 11 which is joined and fixed to the rear end surface portion 22c of the upper formwork 22, and which is positioned such that the circumferential support plate portion 11b is spaced about 180 mm downward from the outer circumferential surface 22b of the upper formwork 22 and extends vertically rearward from the rear end surface portion 22c, an air cushion body 12 which is placed on the cushion base surface 11c of the lap bracket member 11, and a contact surface member 13 which is attached extending circumferentially along the upper surface portion 12a of the air cushion body 12.

[0027] As shown in Figure 3, the lap bracket member 11 is formed by integrally integrating a horizontally elongated strip-shaped joining plate portion 11a that is slightly curved with the same radius of curvature as the upper formwork 22 of the formwork body 21, a circumferential support plate portion 11b that extends perpendicularly from the upper-lower middle portion of the joining plate portion 11a and extends along the length of the joining plate portion 11a while curving with the same radius of curvature as the joining plate portion 11a, and is fixed to the joining plate portion 11a by welding or the like, and a plurality of parallel-arranged (four in this embodiment) substantially right-angled triangular reinforcing rib plates 11d that reinforce the state in which the circumferential support plate portion 11b extends perpendicularly from the joining plate portion 11a, with one side of the right-angle portion fixed to the lower surface of the circumferential support plate portion 11b by welding or the like and the other side fixed to the front surface of the joining plate portion 11a by welding or the like, thereby reinforcing the state in which the circumferential support plate portion 11b extends perpendicularly from the joining plate portion 11a from below.

[0028] Multiple bolt fastening holes 11e (two in this embodiment) are formed in the portion of the joining plate portion 11a above the circumferential support plate portion 11b. By fastening bolts and nuts 15, for example, between these bolt fastening holes 11e and the rear end face portion 22c of the upper formwork 22, the lap portion bracket member 11 can be firmly and integrally attached to a predetermined position on the rear end face portion 22c of the upper formwork 22, for example, approximately 180 mm downward from the outer peripheral surface 22b of the upper formwork 22. The outer peripheral surface that becomes the upper surface of the circumferential support plate portion 11b forms the cushion base surface 11c on which the air cushion body 12 is placed. The lap bracket member 11 has a length of approximately 700 mm in the circumferential direction of the upper formwork 22, and multiple lap bracket members 11 are joined together in a manner that they are integrally connected in the longitudinal direction, so that they can be attached to the rear end face 22c of the upper formwork 22 along its entire length in the circumferential direction.

[0029] The air cushion body 12 can be formed using a synthetic resin airbag-shaped bag member with a flat top surface, which preferably has a known drop-stitch structure that improves shape retention by pulling the upper and lower fabrics together with countless threads, as shown in Figures 1 and 2. When air is injected into the air intake port 12c and the air cushion body 12 is inflated, it has a hollow, roughly oval cross-sectional shape with dimensions such as approximately 250 mm in width and 150 mm in height, and a length such as approximately 1000 mm. The air cushion body 12 is attached to the upper formwork 22 in a continuous arrangement around its circumference by placing its lower surface portion 12b along the cushion base surface 11c on the cushion base surface 11c by the circumferential support plate portion 11b of the wrap portion bracket member 11, and by bonding it, for example, with an adhesive.

[0030] The contact surface member 13 installed on the upper surface portion 12a of the air cushion body 12, which is shaped to follow the inner circumferential surface 30b of the upper end of the pre-facing concrete lining 30, can be formed using, for example, a rigid foamed plastic, preferably foamed polyethylene or rigid foamed urethane. By making the contact surface member 13 attached along the upper surface portion 12a of the air cushion body 12 out of foamed polyethylene or rigid foamed urethane, when the air cushion material is inflated, it becomes easier to position the flat top surface of the contact surface member 13 to conform to the surface of the inner circumferential surface 30b of the upper end of the tip portion 30a of the pre-facing concrete lining 30. This makes it possible to properly and smoothly install the joint material 18 (see Figure 7(b)), which will be described later, in the joint between the tip portion 30a of the pre-facing concrete lining 30 and the newly formed concrete lining. The contact surface member 13 can be formed to have a horizontally elongated rectangular cross-sectional shape, for example, with a width of about 230 mm and a height (thickness) of about 40 mm, and a length of about 2000 mm.

[0031] The contact surface member 13 can be attached to the upper formwork 22 in a continuous arrangement around its circumference by placing its lower surface 13b on the upper surface 12a of the air cushion body 12 and bonding them together, for example, via an adhesive. It is also preferable to attach the contact surface member 13 so that its upper surface, which is the outer peripheral surface 13a, protrudes slightly above the upper surface, which is the outer peripheral surface 22b of the upper formwork 22, by, for example, about 14 mm. This allows the pressure sensor 17 (see Figure 8) installed inside the air cushion body 12 to detect changes in pressure, as will be described later, and recognize that the contact surface member 13 has come into contact with the inner peripheral surface 30b of the upper end of the leading edge portion 30a of the pre-fabricated concrete lining 30. This makes it possible to easily align the outer peripheral surface 22b of the upper formwork 22 to the height of the inner peripheral surface 30b of the upper end of the leading edge portion 30a of the pre-fabricated concrete lining 30 by, for example, stopping the injection of air into the air cushion body 12.

[0032] Furthermore, in this embodiment, a rubber sheet 14 made of soft rubber is attached so as to cover the upper surface, which is the outer peripheral surface 13a of the contact surface member 13, extending from the rear end surface 22c of the upper formwork 22. The rubber sheet 14 is, for example, a soft, flexible strip-shaped member with a thin thickness of about 4 mm, or a thin polyvinyl chloride resin sheet with a thickness of about 3 mm. The rubber sheet 14 has one side edge in the width direction fixed to the upper edge portion of the rear end surface 22c of the upper formwork 22 via a base plate 14a and a retaining plate 14b (see Figure 6(a)), and the other side edge can be folded back to the opposite side from the pre-filled concrete 30 and turned over to face the outer peripheral surface 22b of the rear end portion 22a of the upper formwork 22 (see Figures 6(a) and (b)).

[0033] In order to align the outer peripheral surface 22b of the upper formwork 22 of the formwork body 21 of the tunnel lining formwork 20 to the same height as the inner peripheral surface 30b of the upper end portion 30a of the leading edge portion 30a of the preceding lining concrete 30 using the alignment structure 10 of this embodiment having the above configuration, prior to alignment, the alignment structure 10 is assembled to a predetermined position close to the outer peripheral surface 22b of the rear end surface portion 22c of the upper formwork 22, as shown in Figures 6(a) to (d) and Figures 7(a) to (c). That is, first, one side edge of the rubber plate 14 is fixed to the upper edge portion of the rear end surface portion 22c of the upper formwork 22 via the base plate 14a and the retaining plate 14b using known round-head bolts, etc., and the other side edge portion is turned over to face the outer peripheral surface 22b of the upper formwork 22 (see Figure 6(a)). Furthermore, the lap bracket member 11 is attached to the rear end face portion 22c of the upper formwork 22 using bolts and nuts 15, with the circumferential support plate portion 11b spaced, for example, about 180 mm downward from the outer peripheral surface 22b of the rear end portion 22a of the upper formwork 22, and extending vertically rearward from the rear end face portion 22c (see Figure 6(b)).

[0034] Furthermore, the air cushion body 12 is placed on the cushion base surface 11c of the circumferential support plate portion 11b of the attached wrap portion bracket member 11, and air is injected from the air intake port 12c to inflate the air cushion body 12 until, preferably, a contact surface member 13 made of rigid urethane can be installed on the upper surface portion 12a (see Figure 6(c)), and the contact surface member 13 made of rigid urethane is installed on the upper surface portion 12a of the inflated air cushion body 12 (see Figure 6(d)).

[0035] Subsequently, as shown in Figure 7(a), the rubber sheet 14, preferably made of soft rubber, which had been turned over towards the outer peripheral surface 22b of the rear end portion 22a of the upper formwork 22, is reversed and positioned to cover the outer peripheral surface 13a of the contact surface member 13. With this position, the lifting jack 26 (see Figures 4 and 5), which supports the upper formwork 22 of the formwork body 21 so that it can be raised and lowered, is driven to raise the upper formwork 22 until the upper surface 12a of the air cushion body 12 contacts or comes close to the inner peripheral surface 30b of the upper end portion 30a of the pre-lining concrete 30 via the contact surface member 13 and the rubber sheet 14. The upper formwork 22 is then finely adjusted and set so that the outer peripheral surface 22b of the upper formwork 22 is at the same height as the inner peripheral surface 30b of the upper end portion 30a of the pre-lining concrete 30.

[0036] Once the upper formwork 22 is set to the predetermined height, the air pressure inside the inflated air cushion body 12 is adjusted by injecting more air through the air intake port 12c.

[0037] In this embodiment, when the lifting jack 26 is driven to raise the upper formwork 22, for example, as shown in Figure 8, a first distance sensor 16a can be attached to the outer peripheral surface 22b of the rear end portion 22a of the upper formwork 22 to measure the distance to the front end surface 30c of the pre-filled concrete lining 30, and a second distance sensor 16b can be attached to the circumferential support plate portion 11b of the lap portion bracket member 11 to measure the distance to the inner peripheral surface 30b of the upper end portion 30a of the pre-filled concrete lining 30. These sensors 16a and 16b detect the position of the leading edge surface 30c of the pre-filled concrete 30 and the position of the upper end inner surface 30b of the leading edge portion 30a of the pre-filled concrete 30. This makes it possible to appropriately manage the raising of the upper formwork 22 by the lifting jack 26 and the position of the upper formwork 22 while making fine adjustments, so that the rear end portion 22a of the upper formwork 22 and the lap bracket member 11, which is an overhanging member, do not inadvertently collide with the leading edge portion 30a of the pre-filled concrete 30.

[0038] Furthermore, in this embodiment, a pressure sensor 17 can be provided inside the air cushion body 12. This allows the pressure sensor 17 to detect changes in pressure inside the air cushion body 12, thereby recognizing that the contact surface member 13 has come into contact with the inner circumferential surface 30b of the upper end portion 30a of the pre-fabricated concrete lining 30. For example, by stopping the raising of the upper formwork 22 by the lifting jack 26, the outer circumferential surface 22b of the upper formwork 22 can be easily aligned to the height of the inner circumferential surface 30b of the upper end portion 30a of the pre-fabricated concrete lining 30.

[0039] As a result, with the tunnel lining formwork alignment structure 10 of this embodiment, when installing the tunnel lining formwork 20 on the front portion of the preceding lining concrete 30, the function of positioning the outer peripheral surface 22b of the upper formwork 22 at the same height as the inner peripheral surface 30b of the upper end portion 30a of the preceding lining concrete 30 is not impaired. The lap bracket member 11 is positioned with the circumferential support plate portion 11b positioned considerably below the outer peripheral surface 22b of the rear end portion 22a of the upper formwork 22, and the air cushion body 12 and contact surface member 13 are installed on the lap bracket member 11. This simple configuration makes it possible to more reliably avoid collisions between the upper formwork 22 and the lap bracket member 11, which is an overhanging member, with the edge portion of the leading edge of the preceding lining concrete 30.

[0040] It is preferable to align the outer circumferential surface 22b of the upper formwork 22 to the same height position as the inner circumferential surface 30b of the upper end portion 30a of the pre-filled concrete lining 30, and then, for example, to install the joint material 18 that has been temporarily placed in advance on the outer circumferential surface 22b of the upper formwork 22, by moving it toward the pre-filled concrete lining 30 side via a fastening member inserted through a through-hole 18a, similar to the method of pouring tunnel concrete described in Patent Document 4, thereby installing it in the joint portion with the newly formed concrete lining.

[0041] It should be noted that the present invention is not limited to the embodiments described above and can be modified in various ways. For example, the contact surface member attached along the upper surface of the air cushion body does not necessarily have to be made of rigid urethane, but may be made of other rigid foamed plastics or the like. [Explanation of Symbols]

[0042] 10. Alignment structure for tunnel lining formwork 11. Wrap section bracket member (protruding member) 11a Joint plate section 11b Circumferential support plate section 11c Cushion base surface 11d Reinforcement Rib Plate 11e Bolt fastening hole 12 Air cushion body 12a Top part 12b Bottom part 12c Air supply port 13 Contact surface member 13a Outer surface 14 Rubber sheet 15 Bolts and Nuts 16a First distance sensor 16b Second distance sensor 17. Pressure Sensor 18. Joint material 20 Formwork for tunnel lining 20a Gantry trolley 20b Base part 21 Formwork Body 22 Upper formwork 22a Rear end part 22b Outer surface 22c Rear end section 23 Side formwork 24 Lower end formwork 26 Lifting jacks 27. Lining space 30. Pre-lining concrete 30a Tip part 30b Inner peripheral surface of upper end 40 Tunnel 41 Interior wall surface X Tunnel excavation direction

Claims

1. In mountain tunnel construction, when forming lining concrete using a movable tunnel lining formwork, a tunnel lining formwork alignment structure is provided that allows the outer surface of the rear end portion of the upper formwork that constitutes the formwork body of the tunnel lining formwork to be aligned with the height of the inner surface of the upper end portion of the leading edge portion of the previously formed pre-formed lining concrete. The aforementioned upper formwork is supported so as to be able to move up and down in the vertical direction by a plurality of lifting jacks provided on the base of a gantry-type trolley that constitutes the formwork for tunnel lining. The alignment structure includes a lap bracket member that is joined and fixed to the rear end face of the upper formwork, with its outer surface serving as a cushion base surface, spaced downward from the outer surface of the upper formwork and extending vertically backward from the rear end face, and arranged continuously in the circumferential direction along the outer surface of the upper formwork; an air cushion body that, when inflated by supplied air, has a shape comprising an upper surface portion along the inner surface of the upper end of the leading edge of the pre-facing concrete and a lower surface portion along the cushion base surface, so that when placed on the cushion base surface, the upper surface portion can contact the inner surface of the upper end of the leading edge of the pre-facing concrete with a contact surface member interposed; and a contact surface member that extends circumferentially along the upper surface portion of the air cushion body and is positioned at the same height as the outer surface of the upper formwork. A tunnel lining formwork alignment structure that allows the air cushion body to be inflated so that the outer circumferential surface of the rear end portion of the upper formwork can be aligned to the same height as the inner circumferential surface of the upper end portion of the leading edge of the preceding lining concrete via the air cushion body and the contact surface member.

2. The alignment structure for tunnel lining formwork according to claim 1, wherein a rubber plate made of soft rubber extending from the rear end face of the upper formwork is attached so as to cover the outer peripheral surface of the contact surface member, and the air cushion body is capable of contacting the inner peripheral surface of the upper end of the leading edge of the preceding lining concrete with the contact surface member and the rubber plate interposed between them.

3. The alignment structure for tunnel lining formwork according to claim 1 or 2, wherein the contact surface member attached along the upper surface of the air cushion body is made of rigid urethane.

4. The alignment structure for tunnel lining formwork according to claim 1 or 2, wherein a first distance sensor for measuring the distance to the leading edge surface of the preceding lining concrete is attached to the outer circumferential surface of the rear end portion of the upper formwork, and a second distance sensor for measuring the distance to the inner circumferential surface of the upper end portion of the preceding lining concrete is attached to the circumferential support plate portion.

5. The alignment structure for tunnel lining formwork according to claim 1 or 2, wherein a pressure sensor is provided inside the air cushion body.

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