JP2020122300A - Joint forming unit - Google Patents

Abstract

To provide a joint forming unit capable of easily forming inducing joints in the middle part of each construction span of tunnel lining concrete without requiring much effort.SOLUTION: A formwork for tunnel lining 1 includes a movable frame part 2 and a formwork body 3. The formwork body 3 is constituted of a pair of divided formwork bodies 3A, 3B which are divided into two in the tunnel excavation direction X. Between these adjacent end faces, spaced part of constant width is formed all around. A joint forming unit 50 is constituted of including: a plate mounting pedestal 20 that forms a slit-like gap δ over the entire circumference; and a plate member 15 in which the joint portion forming portion 15A is projected into the lining space S via the slit-like gap δ. By inserting pin members 26 in a state that the pin insertion holes 16A and 23A formed in each are matched, the plate member 15 is attached to the plate mounting base 20 while being supported.SELECTED DRAWING: Figure 5

Description

The present invention relates to a joint forming unit, and more particularly to a joint forming unit for forming an induced joint on tunnel lining concrete covering an inner wall surface of a tunnel in a mountain tunnel method.

For example, in the mountain tunnel construction method, a secondary lining that covers the inner wall surface of the mountain tunnel formed by excavating the ground with a tunnel lining concrete of a predetermined thickness is performed. The following is performed using a tunnel lining formwork called a slide center that is movable along the tunnel excavation direction (front-back direction) (see, for example, Patent Documents 1 to 3).

That is, the tunnel lining formwork is carried into the tunnel, and a lining space of a predetermined thickness is provided between the arch-shaped formwork main body portion provided in the tunnel lining formwork and the inner wall surface of the tunnel. Is formed along the circumferential direction, and the secondary lining is carried out by pouring concrete pumped from the concrete pump into this lining space and hardening it, whereby the inner wall surface of the tunnel has a predetermined thickness. Tunnel lining covered with concrete.

The above-mentioned secondary lining is performed from the rear to the front in the tunnel excavation direction while remounting the tunnel lining formwork at every predetermined construction span of about 10.5 m as the tunnel excavation work progresses. Will be carried out sequentially.

By the way, in the recent tunnel construction method, due to the progress of excavation technology, the excavation time of the facet of the tunnel has been shortened, and the secondary lining process, specifically concrete casting to curing and tunnel lining formwork. The progress of the process until demolding can no longer follow the progress of the excavation process of the face face of the tunnel.

Therefore, in order to accelerate the progress of the process for forming the tunnel lining concrete, for example, the process from assembling the tunnel lining formwork to placing the concrete, and the curing of the placed concrete to the tunnel covering. What was done on a separate day from the process of demolding the working formwork, the process from demolding and moving and reassembling the tunnel lining formwork to placing concrete A construction method is being implemented in which the work is completed in a short time, and the next day is applied exclusively to the concrete curing period.

Further, as another method, instead of the generally used tunnel lining form having an extension of about 10.5 m, preferably a long span tunnel lining form having an extension of about 18 m to 22 m. By using a frame, it is considered to extend the construction span of the tunnel lining concrete in one cycle to shorten the construction period and accelerate the progress of the process for forming the tunnel lining concrete.

Japanese Patent Laid-Open No. 2001-280094 JP, 2003-262096, A JP, 2005-067949, A

By the way, for example, when the construction span of the tunnel lining concrete has a general length of about 10.5 m, the drying shrinkage and the temperature of the concrete at the boundary portion of the tunnel lining concrete in each continuous construction span. By absorbing the cracks caused by shrinkage, it is possible to effectively suppress the occurrence of cracks in the construction span of each tunnel lining concrete.

However, when the latter construction method (construction method using a long span tunnel lining form) is adopted, the construction span in one cycle of the tunnel lining concrete is, for example, from about 10.5 m to about 18 m to 22 m. Since it is extended, there is a problem that cracks are likely to occur due to drying shrinkage and temperature shrinkage in the middle part of the construction span of the long tunnel lining concrete of about 18 m to 22 m.

In order to solve the above problem, it is desirable to provide an induction joint for inducing cracks due to drying shrinkage or temperature shrinkage in the middle of the construction span of tunnel lining concrete with a construction span of 18 m to 22 m.

As a method of providing the above-mentioned induction joint in the middle part of the construction span of the tunnel lining concrete, the cast concrete is hardened, and after removing the tunnel lining formwork, for example, it is hardened using a concrete cutter. A method of forming the induced joint by cutting the inner peripheral surface of the middle part of the construction span of the tunnel lining into a groove shape is considered.

However, when cutting the inner circumferential surface of the hardened tunnel lining concrete into a groove with a concrete cutter, while moving the concrete cutter along the curved cross-sectional shape including the arch-shaped portion of the tunnel lining concrete, Since the work of cutting the inner peripheral surface of the engineered concrete into a groove shape is required, much labor and time are required.

The present invention has been made in view of such a technical problem, and an object thereof is to easily provide an induced joint at an intermediate portion of each construction span of tunnel lining concrete without requiring much labor. It is to provide a joint portion forming unit.

INDUSTRIAL APPLICABILITY The present invention is attached to a long span tunnel lining form frame having a construction span of more than 10.5 m, which is installed when constructing a tunnel lining concrete that covers an inner wall surface of a tunnel in a mountain tunnel construction method. A joint portion forming unit for forming an induced joint on a tunnel lining concrete to be constructed, wherein the tunnel lining form is a pedestal portion movable in a tunnel excavation direction, and the pedestal. And a mold main body which is supported by the section and forms a lining space between the inner wall surface of the tunnel and the inner wall surface of the tunnel. The mold main body is a pair of divided molds divided in the tunnel excavation direction. The pair of divided frame main body portions are configured to be supported by the gantry portion such that a gap portion having a constant width is formed over the entire circumference between the adjacent end surfaces. The joint portion forming unit is fixed over the entire circumference at one end of the one divided mold body portion sandwiching the interval portion of the constant width, so that the other divided mold body portion A plate mounting pedestal that forms a slit-shaped gap over the entire circumference between the end portion and the plate mounting pedestal is detachably attached to form a joint portion forming portion through the slit-shaped gap. In a state where the plate member is projected into the lining space, the plate member is inserted and arranged so that it can be pulled out, and includes a plurality of plate members that are arranged continuously along the entire circumference. Plate-side pin insertion holes are formed in at least two locations of the circumferential-side protruding grip portion, and a joint-portion forming portion of the plate member is projected into the lining space on a mounting surface portion of the plate mounting base. At a position that matches the plate-side pin insertion hole in the state, a pedestal-side pin insertion hole is formed, and by inserting a pin member into the matched plate-side pin insertion hole and pedestal-side pin insertion hole, It is characterized in that the plate member is attached while being supported by the plate attachment base.

Here, a pair of guide members for guiding the insertion of the joint portion forming portion of the plate member into the slit-shaped gap is provided on the mounting surface portion of the plate mounting pedestal so as to project along the insertion direction. It is preferable that a guided member that engages with the pair of guide members is provided on one surface of the inner peripheral protruding grip portion of the plate member so as to project along the insertion direction of the plate member. ..

In addition, the cross-sectional shape of a right-angled triangle or a right-angled trapezoid is erected from the outer peripheral surface of the other divided form body portion located on both sides across the slit-shaped gap and the edge portion of the plate mounting pedestal. It is preferable that the chamfered member having is attached continuously over the entire circumference in the circumferential direction in a state of protruding into the lining space.

Further, a laterally projecting overhanging fastening piece is attached to an inner peripheral side end center portion of one surface of the plate member, and a notch hole is formed in the overhanging fastening piece. A fixing bolt, which is rotatably supported and attached to the notched hole of the overhanging fastening piece, is rotatably supported on the back side of the inner peripheral side end of the mounting surface of the plate mounting base, and is detachably fastened using a nut member. Preferably.

Further, it is preferable that the joint forming portion of the plate member is tapered so as to reduce the thickness toward the tip.

Further, it is preferable that both surfaces of the joint portion forming portion of the plate member are coated with a friction reducing material.

Further, it is preferable that an opening portion for a handle is formed at an inner peripheral side end portion of the inner peripheral side protruding grip portion of the plate member.

Furthermore, at the end portion of the other divided mold body portion sandwiching the interval portion of the constant width between the pair of divided mold body portions, a pair of the plate attachment pedestal and an opposite end are arranged. The pedestal is attached over the entire circumference, and the slit-shaped gap is formed over the entire circumference between the end of the facing pedestal and the end of the plate attachment pedestal. It is preferable that the chamfering member is installed upright from the outer peripheral surface of the end edge portion of the facing pedestal, and is continuously attached over the entire circumference in the circumferential direction.

According to the joint portion forming unit of the present invention, the induced joint can be easily provided at the middle portion of each construction span of the tunnel lining concrete without much labor.

It is a schematic longitudinal cross-sectional view explaining a tunnel lining formwork to which a joint portion forming unit according to a preferred embodiment of the present invention is attached. It is a schematic plan view explaining the tunnel lining formwork to which the joint part formation unit which concerns on one preferable embodiment of this invention was attached. FIG. 3 is a schematic cross-sectional view taken along the line AA of FIG. 2 for explaining the tunnel lining formwork to which the joint portion forming unit according to a preferred embodiment of the present invention is attached. FIG. 3 is a schematic cross-sectional view taken along the line BB of FIG. 2 for explaining the arrangement state of the plate members that form the joint portion forming unit. It is a C section expanded sectional view of FIG. It is a front view of a plate member. FIG. 7 is a side view of the plate member (a view in the direction of arrow D in FIG. 6 ). FIG. 8 is a sectional view taken along line EE of FIG. 7. It is a front view of a plate mounting base. FIG. 11 is a side view of the plate mounting base (a view in the direction of arrow F in FIG. 9 ). It is a front view of an opposing pedestal. FIG. 12 is a side view of a facing pedestal (a view in the direction of arrow G in FIG. 11 ). (A)-(c) is a schematic sectional drawing along AA of FIG. 2 which shows the tunnel lining work in the order of the steps. (A)-(c) is a partial side sectional view which shows the method of placing the top end of the tunnel lining concrete in the tunnel lining work in the order of steps.

A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. The joint formation unit 50 of the present embodiment is, for example, in a tunnel construction method such as a mountain tunnel construction method, as shown in FIGS. 1 and 2, a tunnel lining concrete 4 constructed to cover an inner peripheral surface of an excavated tunnel T. Instead of the tunnel lining formwork having a construction extension of about 10.5 m which is generally used as a tunnel lining formwork 1 called a sentle, a construction extension of about 18 m to 22 m is preferably used. When forming using the long-span tunnel lining form 1 that is provided, it is attached to the space portion d between the pair of divided form main body portions 3A and 3B divided into two, and the tunnel lining concrete 4 It is used as a unit that allows easy formation of an induction joint that induces cracks due to drying shrinkage and temperature shrinkage in the middle of the construction span without much labor.

[Tunnel lining formwork]
First, the structure of the tunnel lining formwork 1 to which the joint portion forming unit 50 according to a preferred embodiment of the present invention is attached will be described below with reference to FIGS. 1 to 3.

In the present embodiment, the tunnel lining formwork 1 is for constructing the tunnel lining concrete 4 that covers the inner wall surface of the tunnel T formed by excavating the ground in the mountain tunnel method. It is configured as a long-span slide center having a construction extension of more than 0.5 m (18 m in this embodiment). In addition, the inner wall surface of the tunnel T before being covered with the tunnel lining concrete 4 is sprayed with concrete to provide a primary lining 5. Further, in the following description, the extension direction of the tunnel T (the left-right direction in FIGS. 1 and 2) is the “front-back direction”, the width direction of the tunnel T is the “left-right direction”, and the wellhead side in the extension direction of the tunnel T is “ The "rear side" and the face side may be referred to as the "front side".

In the present embodiment, as shown in FIGS. 1 and 2, the tunnel lining frame 1 includes a gantry part 2 that is movable along the excavation direction X (see FIG. 1) of the tunnel T, and the gantry part 2. It has a frame main body 3 supported above, and its total length is 18 m long span. Therefore, as will be described later, the construction span L of the tunnel lining concrete 4 formed by using the tunnel lining form 1 is 18 m, which is much longer than the conventional 10.5 m.

Here, as shown in FIGS. 1 and 3, the gantry unit 2 includes a gate type trolley 2A. This gate type trolley 2A includes a base portion 2a and left and right support leg portions 2b that support the base portion 2a. At the lower end portion of each support leg portion 2b, the floor surface of the tunnel T is provided. Traveling parts 7 such as rollers, which can move on a pair of left and right rails 6 laid in parallel along the longitudinal direction (the left-right direction in FIG. 1), are attached. Therefore, the tunnel lining formwork 1 can be moved along the rail 6 in the excavation direction X of the tunnel T (see FIG. 1 ).

The formwork main body 3 is for forming a lining space S having a predetermined thickness with the inner wall surface of the tunnel T covered by the primary lining 5, and the digging direction X( It is composed of a pair of split mold body portions 3A and 3B which are split into two in the left-right direction of FIGS.

As shown in FIG. 3, each of the divided mold body portions 3A and 3B has a shape including an arch-shaped portion along the shape of the inner wall surface of the tunnel T as a whole, and covers the upper portion of the arch-shaped portion. An upper mold 3a for forming a working space S, a pair of left and right side molds 3b for forming a covering space S on the lower side and both side wall portions of the arch-shaped portion of the tunnel T, and a pair of lower parts. The mold 3c is included. Here, the upper mold 3a is supported by a plurality of lifting jacks 8 provided on the base 2a of the portal dolly 2A so as to be vertically movable. Further, the pair of side molds 3b are rotatably connected to the left and right lower ends of the upper mold 3a, and the pair of lower molds 3c are connected to the lower ends of the respective side molds 3b. Each is rotatably connected. The left and right side molds 3b and the lower molds 3c are respectively connected to the other ends of the telescopic jacks 9 and 10 whose one end is connected to the gate type trolley 2A. By expanding and contracting, the upper mold 3a and the side mold 3b can be respectively rotated.

Further, as shown in FIGS. 1 and 3, a plurality of press-fitting connection ports 11a and 11b that can be opened and closed are formed in the upper mold 3a and the side mold 3b of the mold body 3 in the direction X of the tunnel T. Are formed at intervals. Here, the press-fitting connection ports 11a and 11b are used for pouring or press-fitting the lining concrete 12 (see FIGS. 13A to 13C) into the lining space S as described later. Used in.

In the tunnel lining form 1 configured as described above, the form body 3 can be expanded or contracted inward by expanding and contracting the lifting jack 8 and the expansion and contraction jacks 9 and 10. The mold body 3 is assembled along the inner wall surface of T to form a lining space S having a predetermined thickness with the inner wall of the tunnel T, and after the mold body 3 is released from the mold. , The inside of the tunnel T can be moved in the excavation direction X.

By the way, the pair of split mold body portions 3A and 3B, which are divided into two in the tunneling direction X of the tunnel of the mold body portion 3, have a constant width d between the adjacent end faces (FIG. 1, FIG. 2) is supported by the pedestal part 2 so as to be formed over the entire circumference, and a joint part is formed at a space part d between the end faces of the pair of split mold body parts 3A and 3B. The unit 50 is attached over the entire circumference. Since the joint portion forming unit 50 is attached to the gap portion d over the entire circumference thereof, a slit-shaped gap δ (see FIG. 5) having a constant width is provided between the pair of divided form body portions 3A and 3B. It is formed over the entire circumference. Further, in the formed slit-shaped gap δ, each construction span L (=18 m) is supported by the plate mounting base 20 of the joint forming unit 50 and constitutes the joint forming unit 50 together with the plate mounting base 20. A plurality of plate members 15 for forming induced joints in the intermediate portion of the joint are continuously provided over the entire circumference in a state in which the joint portion forming portion 15A is projected into the lining space S and is inserted and arranged so as to be pulled out. Are arranged (see FIG. 4).

[Joint part formation unit]
Next, the configuration of the joint portion forming unit 50 of this embodiment that is used by being attached to the tunnel lining formwork 1 will be described below with reference to FIGS. 4 to 12. The joint portion forming unit 50 of the present embodiment is a space portion d having a constant width in the tunnel lining formwork 1 constituted by the pair of split formwork body portions 3A and 3B described above (see FIGS. 1 and 2). As shown in FIG. 5, the slit is fixed between the ends of one of the divided mold body portions 3A sandwiching the slit, as shown in FIG. Plate mounting pedestal 20 that forms a groove-shaped gap δ over the entire circumference, and by being removably attached to the plate mounting pedestal 20, the joint portion forming portion 15A is placed in the lining space S via the slit-shaped gap δ. It is configured to include a plurality of plate members 15 that are inserted and arranged so that they can be pulled out in a protruding state, and that are arranged continuously over the entire circumference (see FIG. 4 ). Plate-side pin insertion holes 16a are formed in at least two locations (two locations in the present embodiment) of the inner peripheral projecting grip portion 15B of the plate member 15 (see FIG. 6), and the plate mounting pedestal 20 is mounted. In the surface portion 20a, a pedestal side pin insertion hole 23a is formed at a position matching the plate side pin insertion hole 16a in a state where the joint portion forming portion 15A of the plate member 15 is projected into the lining space S (Fig. 9). By inserting the pin member 26 (see FIG. 5) into the matched plate-side pin insertion hole 16a and pedestal-side pin insertion hole 23a, the plate member 15 is attached while being supported by the plate mounting base 20.

Further, in the present embodiment, as shown in FIG. 5, preferably from the outer peripheral surface of the other divided mold body portion 3B and the end edge portion of the plate mounting pedestal 20 which are located on both sides of the slit-shaped gap δ. The chamfering members 21h, 20h having a right-angled triangular shape or a right-angled trapezoidal cross-sectional shape are installed upright and continuously attached over the entire circumference in the circumferential direction in a state of protruding into the lining space S.

Further, in the present embodiment, preferably, the plate mounting pedestal 20 is provided at the end of the other divided mold body portion 3B sandwiching the interval portion d having a constant width between the pair of divided mold body portions 3A and 3B. The opposed pedestals 21 arranged in pairs are integrally attached as a constituent member of the joint portion forming unit 50 over the entire circumference. With the end of the facing pedestal 21 as the end of the other split mold body 3B, a slit-like gap δ is formed over the entire circumference between the end of the plate mounting pedestal 20 and the end. Has become. The chamfering member 21h is continuously installed over the entire circumference in the circumferential direction, standing from the outer peripheral surface of the end edge of the opposing pedestal 21, which is the end edge of the other split formwork body 3B. There is.

In the present embodiment, the plate mounting pedestal 20 that constitutes the joint portion forming unit 50 includes a plurality of plate members 15 (see FIG. 4) that are continuously arranged in the circumferential direction of the lining space S over the entire circumference. A plurality of unit mounting pedestals 20′, which are formed corresponding to each of the plate members 15, are continuously provided in the circumferential direction of the lining space S and are fixed to the ends of one of the divided mold body portions 3A. By doing so, the unit mounting pedestals 20′ that are continuously provided in the circumferential direction are provided as an integrated member. The unit mounting pedestals 20 ′ forming the plate mounting pedestal 20 are each formed by assembling a plate member made of steel, for example, as shown in FIGS. 9 and 10, and are formed inside the lining space S. The outer peripheral surface portion 20b, the side joint surface portions 20c on both sides in the circumferential direction, the end joint surface portion 20d joined to the end portion of one of the divided mold body portions 3A, and the end joint surface portion 20d facing each other. It has a box shape including the mounting surface portion 20a. Inside the box-shaped unit mounting pedestal 20', a plurality of reinforcing rib plates 20e having the same shape as the side joint surface portion 20c are arranged substantially parallel to the side joint surface portion 20c and attached at appropriate positions. Has been.

The outer peripheral surface portion 20b of the unit mounting pedestal 20' that forms the plate mounting pedestal 20 has a curved shape that conforms to the arched shape of the outer peripheral surface of the one divided mold body portion 3A. Thus, the mold surface inside the lining space S is formed together with the outer peripheral surface of the divided mold body 3A. A chamfering member 20h having a right-angled triangular shape or a right-angled trapezoidal cross-sectional shape is attached to the end edge portion of the outer peripheral surface portion 20b on the mounting surface portion 20a side in a state of standing from the outer peripheral surface along the end edge portion. ing.

The side joint surface portion 20c is a rectangular plate portion and has a plurality of bolt fastening holes 20f. By tightening bolt members (not shown) in these bolt tightening holes 20f, adjacent unit mounting pedestals 20' can be integrally joined in the circumferential direction. The end joint surface portion 20d is provided with a laterally long substantially rectangular shape in which the outer peripheral side portion and the inner peripheral side portion are curved along the arch shape of the outer peripheral surface of the split mold body portion 3A, and a plurality of bolt tightening portions are provided. A hole 20f is formed. By fastening a bolt member (not shown) to these bolt fastening holes 20f, each unit mounting pedestal 20' is attached to the end face joining plate 3d provided at the end of one of the divided mold body portions 3A. (See FIG. 5) can be integrally joined.

The mounting surface portion 20a is a portion that guides the plate member 15 in the insertion direction when the plate member 15 is inserted into the lining space S via the slit-shaped gap δ and supports the plate member 15 in a temporarily fixed state. And is provided with a horizontally long substantially rectangular shape in which the outer peripheral side portion and the inner peripheral side portion are curved along the arch shape of the outer peripheral surface of the split mold body portion 3A, similar to the end joint surface portion 20d. ing. On the surface of the mounting surface portion 20a, a strip plate-shaped reinforcing plate 20g is integrally joined to the central portion in the vertical width direction, extending in the horizontal width direction, and arranged on both end portions of the reinforcing plate 20g. The pedestal-side pin insertion holes 23a are formed in two places, penetrating the reinforcing plate 20g and the mounting surface portion 20a. Further, on the surface of the mounting surface portion 20a, a pair of guide ridges 24a extend in the vertical width direction that is the insertion direction of the plate member 15, and a pair of guide ridges 24a serve as rib-shaped guide members on both end portions of the reinforcing plate 20g. , Are arranged in parallel and are integrally joined. The pair of guide ridges 24a has a space between the outer side portions, and the space between the outer side portions is formed as a rib-shaped guided member on one surface of an inner peripheral protruding grip portion 15B of the plate member 15, which will be described later. The guide protrusions 24b are provided so as to project in the insertion direction of the plate member 15 so as to have the same distance as the distance between the inner side portions of the guide protrusions 24b. The insertion direction into the gap δ can be guided.

Further, in the present embodiment, the rotation support bracket 25a is integrally joined to the back surface side of the inner peripheral side end portion in the central portion of the mounting surface portion 20a so as to project from the portion close to the inner peripheral side portion ( (See FIG. 10). A fixing bolt 25b and a nut member 25c screwed to the fixing bolt 25b, which are supported by the rotation support bracket 25a, are rotatably supported by a rotation shaft 25d so as to be vertically rotatable (see FIGS. 5 and 9). .. The fixing bolt 25b is provided with the plate member 15 in the lining space S via the slit-shaped gap δ, and the cutout hole 18a (FIG. 7, 8), the nut member 25c can be used for tightening (see FIG. 5).

The facing pedestal 21 that is paired with the plate mounting pedestal 20 and is attached to the end of the other split formwork main body portion 3B extends over the entire circumference in the circumferential direction of the lining space S, similarly to the plate mounting pedestal 20. In the circumferential direction of the lining space S, a plurality of unit facing pedestals 21′ formed in correspondence with each of the plurality of plate members 15 (see FIG. 4) arranged in series are arranged in the circumferential direction of the lining space S. The unit facing pedestals 21 ′, which are continuously provided in the circumferential direction, are provided as an integrated member by continuously providing and fixing the ends to the other divided form body 3</b>B. The unit facing pedestals 21 ′ forming the facing pedestal 21 are each formed by assembling a plate member made of steel, for example, as shown in FIGS. 11 and 12, and are formed with the mold surface inside the lining space S. It has a box shape including an outer peripheral surface portion 21b, a side joint surface portion 21c on both sides in the circumferential direction, and an end joint surface portion 21d that is joined to the end portion of the other divided mold body portion 3B. Inside the box-shaped unit mounting pedestal 20', a plurality of reinforcing rib plates 21e having the same shape as the side joint surface portion 21c are arranged substantially parallel to the side joint surface portion 21c and attached at appropriate positions. Has been.

The outer peripheral surface portion 21b of the unit opposing pedestal 21′ forming the opposing pedestal 21 has a curved shape along the transverse shape that curves in the arch shape of the outer peripheral surface of the other divided form body portion 3B. The mold surface inside the lining space S is formed together with the outer peripheral surface of the divided mold main body 3B. A chamfering member 21h having a right-angled triangular shape or a right-angled trapezoidal cross-sectional shape is provided upright from the outer peripheral surface along the end edge portion of the outer peripheral surface portion 21b opposite to the end joint surface portion 21d. It is installed in the condition

The side joint surface portion 21c is a substantially L-shaped plate portion in which one corner portion of a rectangular shape is cut out in a concave shape, and a plurality of bolt fastening holes 21f are formed. By tightening bolt members (not shown) in these bolt tightening holes 21f, adjacent unit facing pedestals 21' can be integrally joined in the circumferential direction. The end joint surface portion 21d is provided with a laterally long substantially rectangular shape in which the outer peripheral side portion and the inner peripheral side portion are curved along the arch shape of the outer peripheral surface of the split mold body portion 3B, and a plurality of bolt tightening portions are provided. A hole 21f is formed. By fastening a bolt member (not shown) to these bolt fastening holes 21f, each unit facing pedestal 21' is attached to the end face joining plate 3e provided at the end of the other split mold body portion 3B. (See FIG. 5) can be integrally joined.

As shown in FIGS. 6 to 8, the plate member 15 that constitutes the joint forming unit 50 together with the plate mounting pedestal 20 and the facing pedestal 21 is preferably made of aluminum or steel and has a thickness of, for example, about 6 to 10 mm (this In the embodiment, it is formed using a metal plate having a thickness of about 7 mm). Further, the plate member 15 has, for example, a vertical width of about 300 to 600 mm and a horizontal width of about 400 to 700 mm, and an outer peripheral side portion, and an inner peripheral side portion arranged to face the outer peripheral side portion. It has a quadrangular planar shape having left and right side portions. The outer peripheral side portion has a curved shape along the circumferential curved shape of the mold surface formed by the outer peripheral portions of the divided mold body portions 3A and 3B, the plate mounting pedestal 20, and the facing pedestal 21. The plate member 15 has a joint portion forming portion 15A (hatched portion in FIG. 6) in which the outer peripheral side portion is arranged so as to project from the mold surface to the lining space S side, and the inner peripheral side The portion on the side of the side portion is an inner circumferential side protruding grip portion 15B that is arranged so as to project inside the mold surface.

As shown in FIG. 5, the joint portion forming portion 15A is a slit-shaped gap provided in the portion between the edge portion of the plate mounting pedestal 20 and the edge portion of the facing pedestal 21 so as to extend in the circumferential direction. When the plate member 15 is inserted toward the lining space S via δ, it projects outward from the mold surface formed by the outer peripheral portions of the plate mounting pedestal 20 and the counter pedestal 21 at a projecting height of, for example, about 200 mm. Arranged to do so. Further, the joint portion forming portion 15A is tapered to reduce the thickness toward the tip from, for example, about 7 mm to about 2 mm, and preferably, both sides of the joint portion forming portion 15A of the plate member 15 are provided. Is coated with a friction reducing material containing a superabsorbent resin known as a material that absorbs water and swells, such as a friction reducing material containing an acrylic resin having a high water absorbing property. As a result, after the concrete cast in the lining space S has hardened, the operation of pulling out the plate member 15 to the inside of the mold body 3 can be performed more smoothly.

The inner circumferential side protruding grip portion 15B functions as a temporary fixing portion for fixing the plate member 15 to the plate mounting pedestal 20 until the concrete cast in the lining space S hardens, and the concrete It is a portion that functions as a handle when the plate member 15 is pulled out to the inside of the tunnel lining frame 1 after being cured. As shown in FIGS. 6 and 7, a center line c in the lateral width direction is formed on a surface (a surface on the front side in FIG. 6) opposite to the surface facing the plate mounting base 20 in the inner peripheral side protruding grip portion 15B. Circular bosses 16 are provided symmetrically on both sides with the circular bosses 16 projecting integrally, and the circular bosses 16 and the plate member 15 penetrate through the central portions of the circular bosses 16 to form plate-side pins. Each insertion hole 16a is formed. The plate-side pin insertion hole 16a coincides with the pedestal-side pin insertion hole 23a formed in the mounting surface portion 20a of the plate mounting pedestal 20 in a state where the joint portion forming portion 15A of the plate member 15 is projected into the lining space S. It is formed by being arranged at a position (see FIGS. 5 and 9). As a result, as described above, the plate member 15 is supported by the plate mounting pedestal 20 by inserting the pin member 26 (see FIG. 5) into the matched plate-side pin insertion hole 16a and pedestal-side pin insertion hole 23a. It can be installed in a closed state.

Further, in the present embodiment, the surface of the inner peripheral side protruding grip portion 15B facing the plate mounting pedestal 20 (the surface on the front side in FIG. 6) is located outside the circular boss 16 on the opposite surface in the lateral width direction. The pair of guided ridges 24b are arranged as rib-shaped guided members extending in the vertical width direction that is the insertion direction of the plate member 15 and integrated in a state of being arranged in parallel and protruding. Are joined as. The distance between the inner side portions of the pair of guided ridges 24b is the same as the distance between the outer side portions of the pair of guide ridges 24a projecting from the mounting surface portion 20a of the plate mounting base 20. So that the plate member 15 is protruded in the insertion direction, and thus, as described above, the insertion direction of the plate member 15 into the slit-shaped gap δ of the joint forming portion 15A is guided. The guide 24b can be guided in a stable state along the guide ridge 24a.

Further, in the present embodiment, the plate member 15 is formed on the inner peripheral side end portion of the inner peripheral side protruding grip portion 15B close to the inner peripheral side portion after the concrete cast in the lining space S is cured. An opening 19 for a handle having a horizontally long rectangular shape, which functions as a handle when pulling out to the inside of the main body 3, is symmetrically arranged on both sides of the center line c in the horizontal width direction to form a pair of openings. There is.

Furthermore, in the present embodiment, the inner peripheral side end portion of the inner peripheral side protruding grip portion 15B that is close to the inner peripheral side portion is vertically projected from the central portion in the lateral width direction of the surface facing the plate mounting pedestal 20. The overhanging fastening piece 18 is integrally joined. As shown in FIG. 8, a cutout hole 18a is formed in the overhanging fastening piece 18 so as to be cut out in a U-shape from the side portion on the overhanging tip side to the base end side. As described above, the notch hole 18a is rotatably supported on the back surface side of the inner peripheral side end of the plate mounting pedestal 20 in a state where the joint portion forming portion 15A of the plate member 15 is projected into the lining space S. The fixing bolt 25b rotatably supported and attached via the bracket 25a can be detachably fastened using a nut member 25c (see FIG. 5).

In the present embodiment, as shown in FIG. 4, the joint portion forming portion 15A is projected toward the lining space S side from the mold surface formed by the outer peripheral surface portion 21b of the plate mounting pedestal 20 to extend in the circumferential direction of the mold body portion 3. The plurality of plate members 15 arranged in series are preferably arranged so that no gap is formed between the side edges of the pair of adjacent plate members 15. In addition, in some of the plurality of plate members 15 arranged in a row, the distance between the side portions on both sides is increased from the outer side to the inner side of the lining space S. It is a V-shaped plate member 15' having a divergent front shape.

A part of the plurality of plate members 15 arranged in a row in the circumferential direction has a V-shaped plate member 15 ′ in which the distance between the side portions on both sides spreads toward the inside of the lining space S. Accordingly, by pulling out the C-shaped plate member 15 ′ in advance, the plate members 15 continuously arranged in the circumferential direction of the mold body 3 are adjacent plate members. It is possible to avoid the difficulty of pulling out due to the side edge portions of 15 competing with each other and to smoothly pull out each plate member 15.

In order to install the joint portion forming unit 50 of the present embodiment having the above-described configuration, a pair of divided mold body portions 3A that are supported by the gantry portion 2 and that constitute the mold body portion 3 are divided into two. By mounting the plate mounting pedestal 20 and the opposing pedestal 21 arranged in a pair with the plate mounting pedestal 20 in the space portion d between the end faces of 3B, over the entire circumference of the split mold body portions 3A, 3B, A slit-shaped gap δ is formed over the entire circumference between these ends. That is, as described above, the plate mounting pedestal 20 integrally joins the plurality of unit mounting pedestals 20′ in the circumferential direction, and the end face joining plate 3d provided at the end of the one divided mold body portion 3A. It can be easily attached to the end of one of the divided mold main body portions 3A by integrally joining the two. In addition, as described above, the facing pedestal 21 joins the plurality of unit facing pedestals 21′ integrally in the circumferential direction, and at the same time, to the end face joining plate 3e provided at the end of the other split mold body portion 3B. By joining as one piece, it can be easily attached to the end of the other split formwork body 3B. The slit-shaped gap δ is obtained by integrally joining a plurality of unit mounting pedestals 20′ and unit opposing pedestals 21′ to the end face joint plates 3d and 3e, and attaching the plate mounting pedestals 20 and opposing pedestals 21 to the ends in advance. The pair of split formwork main body portions 3A, 3B thus supported are each supported by the pedestal portion 2 and installed at a predetermined position, so that the entire circumference is provided between the end portion of the plate mounting pedestal 20 and the end portion of the opposing pedestal 21. It can also be formed over.

By mounting the plate mounting pedestal 20 and the facing pedestal 21 in the space portion d between the end surfaces of the pair of split formwork main body portions 3A and 3B, a slit-shaped gap δ is formed between the end portions. Once formed, the joint portions forming portions 15A are inserted into the slit-shaped gaps δ, and the joint portion forming portions 15A are pulled out to the lining space S through the slit-shaped gaps δ. The plate mounting bases 20 are mounted so that they can be projected as much as possible and are continuously arranged over the entire circumference. As described above, the operation of inserting the plurality of plate members 15 into the slit-shaped gap δ is performed by projecting on the mounting surface portion 20a of each unit mounting pedestal 20′ provided corresponding to the number of the plate members 15. The pair of guide ridges 24a thus formed are provided along the guided ridges 24b that are provided so as to project on the surface of the plate member 15 that faces the mounting surface portion 20a, thereby stabilizing the insertion direction of the plate member 15. It can be done smoothly.

In addition, a plurality of plate members 15 are inserted into the slit-shaped gaps δ so that the pair of plate-side pin insertion holes 16a formed in the plate member 15 are attached to the unit mounting pedestals 20′ of the plate mounting pedestal 20. After matching the pair of pedestal side pin insertion holes 23a formed in the surface portion 20a, as described above, by inserting the pin member 26 into these matched pin insertion holes 16a, 23a, each plate member 15 With the joint portion forming portion 15A protruding into the lining space S through the slit-shaped gap δ, the joint portion forming portion 15A can be supported and attached to the plate attachment base 20.

In the present embodiment, in addition to inserting the pin member 26 into the matched pin insertion holes 16a and 23a, as described above, the inner peripheral side of the surface of each plate member 15 that faces the plate mounting pedestal 20. The fixing bolt 25b rotatably supported and attached to the rear surface side of the attachment surface portion 20a of the plate attachment pedestal 20 in the cutout hole 18a of the overhanging fastening piece 18 provided so as to extend from the end is provided with a nut member. It is designed to be fastened using 25c. This makes it possible to more stably attach each plate member 15 to the plate mounting pedestal 20 in a state where the joint portion forming portion 15A is projected into the lining space S. Further, as a result, when the plate member 15 is pulled out to the inside of the mold body 3 after the concrete cast in the lining space S has hardened, the plate side pin insertion hole 16a and the pedestal side pin insertion hole 23a which are matched with each other are pulled out. Even if the pin member 26 is removed, the plate member 15 can be easily pulled out by the tapering process or the action of the friction reducing material, so that the plate member 15 can be effectively prevented from falling due to its own weight.

As described above, the joint portion forming unit 50 of the present embodiment is configured such that the joint portion forming portions 15A of the plurality of plate members 15 are projected into the lining space S and are continuously arranged over the entire circumference in the mold. The frame body 3 is installed in the space portion d between the end faces of the pair of divided mold body portions 3A and 3B, which are divided into two, and is integrally attached to the frame body portion 3. In the present embodiment, when the joint portion forming unit 50 is installed in the space portion d between the end faces of the pair of split mold body portions 3A and 3B, the primary lining work of the tunnel T is performed by the tunnel lining work as described below. Concrete is poured into the lining space S between the inner wall surface provided with 5 and the mold surface of the outer peripheral portion of the mold main body portion 3 to form the tunnel lining concrete 4.

[Tunnel lining work]
In the present embodiment, the tunnel lining work is performed from the two concrete pumps 30 by using the tunnel lining formwork 1 as shown in FIGS. 1, 2 and 13A to 13C. The tunnel lining concrete that covers the inner wall surface of the excavated tunnel T by pouring the concrete 12 (see FIGS. 13A to 13C) into the lining space S at the same time through the respective pressure-feeding pipes 31 that extend. This is the work to build 4.

More specifically, as shown in FIG. 1 and FIG. 2, the two concrete pumps 30 sandwich the tunnel lining formwork 1 carried into the tunnel T and are located in front of and behind the tunneling direction X of the tunnel T. The concrete 12 is loaded into the hopper of each concrete pump 30 from each concrete mixer truck 32. Here, the pressure feed pipes 31 extend from the two front and rear concrete pumps 30, respectively, and the concrete 12 injected into the hopper portion of each concrete pump 30 from each concrete mixer truck 32 has two lines of the respective pressure feed pipes 31. Are simultaneously pumped and supplied to the lining space S. As described above, by using the two-system concrete pump 30 and the pressure-feeding pipe 31, it is possible to effectively accelerate the progress of the process for forming the tunnel lining concrete 4. When two concrete pumps 30 are used, these two concrete pumps 30 are arranged side by side on one side (on one side) of the front or the rear of the tunnel lining formwork 1 in the tunneling direction X of the tunnel T. It is also possible to do so.

The two systems of pumping pipes 31 extending from the two concrete pumps 30 are a main pipe 31a extending toward the inside of the tunnel lining form 1, and a width of the tunnel T from the main pipe 31a via the rotary valve 29. It is configured to include left and right branch pipes 31b branched on both sides in the direction. Here, each branch pipe 31b is configured such that the branch pipe 31b includes a plurality of piece pipes such as straight pipes and curved pipes having different lengths. The branch pipe 31b is arranged so as to be connected to the mouths 11a and 11b, and by recombining these pieces, the branch pipe 31b is preferably divided into two parts of the mold body 3 which are divided into two parts. The lower press-fitting connection port 11a formed at the rear end of each excavation direction X is switched from the lower press-fitting connection port 11a to the upper press-fitting connection port 11b, or the upper press-fitting connection port 11b is connected to the zenith press-fitting connection port 27a, 27b. You can switch to and connect.

That is, as shown in FIG. 13A, the left and right branch pipes 31b are connected to the lower press-fitting connection ports 11a, and the concrete 12 pumped from each concrete pump 30 is supplied from each branch pipe 31b to the lining space S. The concrete 12 can be poured into the lower half portion of the lining space S (dot portion and hatching portion in the lower half portion in FIG. 13A) by pouring or press-fitting the same simultaneously.

Next, as shown in FIG. 13B, the left and right branch pipes 31b are connected to the upper press-fitting connection port 11b, and the concrete 12 pumped from each concrete pump 30 is supplied from each branch pipe 31b to the lining space S. The concrete 12 can be poured into the upper half portion of the lining space S (dot portion and hatching portion in the upper half portion in FIG. 13B) by pouring or press-fitting the same simultaneously.

Finally, as shown in FIG. 13(c), the left and right branch pipes 31b are connected to the press-fitting connection ports 27a and 27b at the zenith, and the concrete 12 pumped from each concrete pump 30 is fed from each branch pipe 31b. By press-fitting into the lining space S at the same time, the concrete 12 can be poured into the zenith (the shaded portion in FIG. 13C) of the lining space S. In this case, the joint portion forming portion 15A of the plate member 15 that is continuously arranged over the entire circumference so as to project into the lining space S at the space portion d between the end surfaces of the pair of split formwork main body portions 3A and 3B. Functions as a baffle as shown in FIGS. 14(a) to 14(c).

That is, the concrete 12 is removed from the press-fitting connection ports 27a and 27b provided at the rear ends of the front and rear divided form body portions 3A and 3B of the form body portion 3 of the tunnel lining form 1. When pouring into the zenith of the lining space S at the same time, the concrete 12 poured into the lining space S is connected to the gable form 33 from the press-fitting connection ports 27a and 27b as shown by the arrows in FIG. 14(a). Each flows toward the side. Then, as shown in FIG. 14B, the concrete 12 reaching the joint portion forming portion 15A of the plate member 15 from the upstream side is washed up at the joint portion forming portion 15A functioning as a baffle and is pressed into each joint. Flows from the connection ports 27a and 27b toward the gable form 33, respectively. That is, after the concrete 12 flowing from the press-fitting connection ports 27a and 27b toward the gable form 33 reaches the joint portion forming part 15A and the gable form 33 by further press-fitting the concrete 12 into the lining space S. Since further flow to the gable form 33 side is blocked, the gall will be lifted upward along the joint forming portion 15A and the gable form 33. Then, the concrete 12 poured into the lining space S from the press-fitting connection port 27a of one of the divided mold body portions 3A flows over to the existing tunnel lining concrete 4a side over the divided mold body portion 3A. Then, while merging with the concrete 12 on the side of the existing tunnel lining concrete 4a, it reaches the top surface portion of the lining space S from the portion on the press-fitting connection port 27b side, and the lining space S faces toward the gable form 33 side. It is filled one by one.

As described above, when the concrete 12 cast from the press-fitting connection ports 27a and 27b reaches the top surface portion of the lining space S, for example, air remaining on the existing tunnel lining concrete 4a side than the plate member 15 is left. However, since the escape area is lost, air is likely to be generated in the portion of the lining space S that is close to the top surface. Therefore, in the present embodiment, the plate mounting pedestal 20 or the facing pedestal 21 constituting the joint portion forming unit 50 is projected at a length from the mold surface of the top end portion to the portion close to the top surface portion of the lining space S. It is preferable that the air bleeding pipe 28 is attached so as to be able to be pulled out. As a result, the air bleeding pipe 28 is provided so as to project close to the joint portion forming portion 15A of the plate member 15 projecting into the lining space S and reach the portion close to the top surface portion of the lining space S. The remaining air can be released from the air bleeding pipe 28 into the inside of the tunnel lining formwork 1. As a result, as shown in FIG. 14C, the lining space S at the top end is densely filled with the concrete 12 without causing air pockets in the top surface of the lining space S near the plate member 15. can do. In the present embodiment, since the plurality of expandable vibrators 13 are arranged at appropriate intervals in the extension direction of the tunnel T, the concrete 12 cast at the top end of the lining space S is compacted by the expandable vibrators 13. Therefore, it is possible to obtain a more compact and high-quality tunnel lining concrete 4.

Then, in the present embodiment, when the concrete 12 cast in the lining space S by the tunnel lining work is hardened and the tunnel lining concrete 4 is formed, each of the plurality of plate members 15 is covered. The work for forming the induced joint is performed by pulling out from the work space S to the inside of the mold body 3.

That is, from the state in which the plate member 15 shown in FIG. 5 is supported and attached to the plate attachment base 20, the pin member 26 inserted into the matched plate side pin insertion hole 16a and the corresponding base side pin insertion hole 23a is pulled out. Remove. Since the fixing bolt 25b of the plate mounting base 20 is fastened to the overhanging fastening piece 18 of the plate member 15, the work of pulling out the pin member 26 can be performed in a stable state without dropping the plate member 15. It will be possible. When the pin member 26 is removed from the pin insertion holes 16a and 23a, the nut member 25c is loosened, the fixing bolt 25b is released from the overhanging fastening piece 18 and removed, and the pin member 26 is formed on the inner peripheral side end portion of the plate member 15. By locking a hand or a finger in the opening 19 for the handle, for example, a manual operation by an operator makes it easy and smooth to pull the plate member 15 out of the lining space S into the inside of the mold body 3. It will be possible to do. Further, as a result, in the tunnel lining concrete 4, the induced joint due to the portion where the joint portion forming portion 15A of the plate member 15 is pulled out is easily formed along the slit-shaped gap δ.

Further, according to the present embodiment, the joint portion forming portion 15A of the plate member 15 is tapered, and both surfaces of the joint portion forming portion 15A are preferably a friction reducing material containing a superabsorbent resin. Since the concrete 12 cast in the lining space S is hardened, the operation of pulling out the plate member 15 to the inside of the mold body 3 can be performed more smoothly.

Furthermore, according to the present embodiment, a right-angled triangular shape or a right-angled trapezoidal cross section is erected from the outer peripheral surfaces of the edge portions of the plate mounting pedestal 20 and the facing pedestal 21 located on both sides of the slit-shaped gap. Since the chamfered members 20h and 21h each having a shape are continuously attached over the entire circumference in the circumferential direction in a state of protruding into the lining space S, the joint forming portion 15A of the plate member 15 from the lining space S. It is possible to effectively prevent the corner portion of the induced joint from being chipped when pulling out the joint, and to reduce the adhesion area of the joint portion forming portion 15A of the plate member 15 with the tunnel lining concrete 4. By reducing the number, it becomes possible to more smoothly perform the operation of pulling out the plate member 15 to the inside of the mold body 3.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made. For example, a chamfer having a right-angled triangular shape or a right-angled trapezoidal cross-sectional shape, which is erected from the outer peripheral surface of the other divided form body portion and the end edge portion of the plate mounting pedestal located on both sides across a slit-shaped gap. The members do not necessarily have to be attached, and the opposite pedestal arranged in pair with the plate attachment pedestal is attached to the end of the other divided mold body portion sandwiching the interval portion of a constant width. Not necessarily necessary. The plate mounting pedestal can be used by being attached to the rear end of one of the divided form main body portions arranged on the front side in the tunnel excavation direction, and the other divided portion arranged on the rear side in the tunnel excavation direction. It can also be used by attaching to the front end of the mold body.

1 Tunnel lining formwork 2 Frame part 2A Gate form dolly 2a Base part 2b Support leg part 3 Formwork body parts 3A, 3B Split formwork body part 3a Upper formwork 3b Side formwork 3c Lower formwork 4 Tunnel Lining concrete 5 Primary lining 6 Rail 7 Traveling part 8 Elevating jacks 9, 10 Telescopic jacks 11a, 11b Press-fitting connection port 13 Telescopic vibrator 15 Plate member 15' C-shaped plate member 15A Joint part forming part 15B Inner peripheral side projection Grip 16A Plate side pin insertion hole (pin insertion hole)
20 Plate mounting base 21 Opposing base 23A Base side pin insertion hole (pin insertion hole)
26 pin member 28 air bleeding pipe 30 concrete pump (concrete pump car)
31 pumping pipe 31b branch pipe 32 concrete mixer car 50 joint forming unit δ gap S lining space T tunnel X tunnel excavation direction (forward and backward direction of tunnel lining formwork)

Claims (8)

Installed when constructing a tunnel lining concrete that covers the inner wall surface of a tunnel in the mountain tunnel method, and is used by being attached to a long span tunnel lining form with a construction span of more than 10.5 m. A joint part forming unit for forming an induced joint in a tunnel lining concrete to be constructed,
The tunnel lining form comprises a gantry part movable in the tunnel excavation direction, and a formwork main part supported by the gantry part to form a lining space between the inner wall surface of the tunnel. Cage,
The formwork body part is composed of a pair of divided formwork body parts that are divided into two in the tunnel excavation direction, and the pair of divided formwork body parts have a constant width between their adjacent end faces. Is supported by the pedestal so that the interval portion of is formed over the entire circumference,
The joint portion forming unit is fixed over the entire circumference to one end portion of the one part of the divided mold body portion sandwiching the interval portion of the constant width, so that the other end portion of the other divided mold body portion. And a plate mounting pedestal that forms a slit-shaped gap over the entire circumference, and by being detachably attached to the plate mounting pedestal, the joint portion forming portion is covered by the slit-shaped gap. In a state of being projected into the work space, it is arranged to be inserted so that it can be pulled out, and is configured to include a plurality of plate members that are arranged continuously over the entire circumference,
Plate-side pin insertion holes are formed at least at two locations on the inner peripheral protruding grip of the plate member, and the joint surface forming portion of the plate member is lined on the mounting surface portion of the plate mounting base. A pedestal side pin insertion hole is formed at a position that matches the plate side pin insertion hole in a state of being projected into the space,
A joint portion forming unit in which the plate member is mounted while being supported by the plate mounting pedestal by inserting a pin member into the plate-side pin insertion hole and the pedestal-side pin insertion hole that match each other. A pair of guide members, which guide the insertion of the joint portion forming portion of the plate member into the slit-shaped gap, are provided on the mounting surface portion of the plate mounting pedestal so as to project along the insertion direction. The joint member according to claim 1, wherein a guided member that engages with the pair of guide members is provided on one surface of the inner peripheral protruding grip portion of the member so as to project along the insertion direction of the plate member. Part formation unit. Standing up from the outer peripheral surface of the other divided mold body portion and the end edge portion of the plate mounting pedestal located on both sides across the slit-shaped gap, it has a right-angled triangular shape or a right-angled trapezoidal cross-sectional shape. The joint portion forming unit according to claim 1 or 2, wherein the chamfering member is continuously attached in the circumferential direction over the entire circumference in a state of protruding into the lining space. At the center of the inner peripheral end of one surface of the plate member, a laterally projecting fastening piece is attached, and the projecting fastening piece is formed with a cutout hole. A fixing bolt, which is rotatably supported and attached to the notch hole of the fastening piece, is rotatably supported and attached to the rear surface side of the inner peripheral side end of the mounting surface portion of the plate mounting pedestal using a nut member. The joint part forming unit according to any one of claims 1 to 3. The joint portion forming unit according to any one of claims 1 to 4, wherein the joint portion forming portion of the plate member is tapered to reduce the thickness toward the tip. The joint portion forming unit according to claim 5, wherein both surfaces of the joint portion forming portion of the plate member are covered with a friction reducing material. The joint portion forming unit according to any one of claims 1 to 6, wherein an opening portion for a handle is formed at an inner peripheral side end portion of the inner peripheral side protruding grip portion of the plate member. At the end portion of the other divided mold body portion sandwiching the interval portion of the constant width between the pair of divided mold body portions, an opposing pedestal arranged in pair with the plate mounting pedestal is entirely formed. The slit-shaped gap is formed over the entire circumference between the end of the facing pedestal and the end of the plate mounting pedestal. The joint portion forming unit according to any one of claims 3 to 7, wherein the chamfering member is provided upright from an outer peripheral surface of an end edge portion of the pedestal, and the chamfering member is continuously attached over the entire circumference in a circumferential direction.

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