JP2024096508A - Fixing device and method for friction cut plate in concrete box driving - Google Patents

Abstract

[Problem] To provide a fixing device and a fixing method for a friction cut plate in an open shield construction method for a concrete box, which can prevent the friction cut plate arranged on the top surface of a box from moving together with the box when the box is advanced using simple equipment.
[Solution] A base jack is installed in front of a support wall installed in the starting shaft, and when this base jack is used to propel the concrete box, a fixing device consisting of a hanging girder that is laid horizontally on the ends of parallel friction cut plates laid on the top surface of the concrete box, a support member that is placed between the support wall and the base jack, and a framework that connects these hanging girder and support member is used, and the friction cut plate is prevented from moving by the concrete box propulsion reaction force transmitted to the rear end of the base jack when the base jack is extended.
[Selected Figure] Figure 1

Description

The present invention relates to a fixing device and fixing method for friction cut plates in concrete box driving.

In narrow construction locations with houses close to both sides, or when there are overhead restrictions, such as laying a box conduit across an existing bridge, or crossing under an elevated railway bridge, an open shield method may be used, using an open shield machine with open front, back, and top, consisting of left and right side panels and a bottom panel connected to these side panels. The open shield machine is advanced by a shield jack using the reaction force of the concrete box, and the concrete box is advanced and laid in sequence by a push jack installed in the starting shaft.

In the open shield method, the width of the open shield machine 1 is the same as that of the concrete box to be laid, and the tips of the side wall plate 1a and bottom plate are formed as cutting edges, and shield jacks 3 are arranged vertically facing rearward near the center or rear end of the side wall plate 1a. The side wall portion of the cutting edges is divided and formed movable as a sliding retaining wall 17 (see Figure 11).

As shown in Figures 9 and 10, the starting shaft 8 is equipped with a push jack 14 mounted on a jack stand 27, and a bearing wall 9 for supporting the thrust reaction force of the concrete box 4 caused by the extension of the push jack 14. The bearing wall 9 is made of steel members arranged in a grid pattern, or plain concrete is poured, and reinforced concrete is used if necessary.

In addition, H-beams are arranged in a rail-like manner in the starting shaft 8, and a steel plate is placed over the entire top of them to form a support 18 for installing and starting the shield machine.

The open shield machine 1 is installed in the starting shaft 8 and advanced, and the concrete box body 4 is placed between the open shield machine 1 and the base jack 14 and advanced using the base jack 14. Backfill soil such as sand is applied to the top of the concrete box body 4.

In the figure, 23 denotes a friction cut plate that is installed to cut the edge between the box body and the backfill soil and propel only the box body. It is made of strip-shaped thin steel plates, etc., and is laid in parallel on top of the concrete box body 4. Each plate is made long by connecting shorter ones by welding, etc., and is installed from the point where it exits the starting shaft 8.

The open shield machine 1 is advanced by a shield jack 3 installed inside the machine, using the reaction force of the laid concrete box 4.

Next, the main jack 14 is extended forward using the reaction force of the bearing wall 9, and the process moves to the box pushing process, in which all of the concrete boxes 4 laid inside the starting shaft 8 are pushed forward.

The friction cut plates 23 are laid in parallel on the top surface of the concrete box 4, and a hanging beam 25 is placed across the ends of the friction cut plates 23. The friction cut plates 23 are fixed to the hanging beam 25 with a triangular locking flange 24 protruding from the friction cut plates 23.

The ends of the hanging beam 25 are engaged with the retaining sheet piles 11 at both ends of the entrance of the front of the starting shaft 8.

In this way, the friction cut plate 23 is pulled forward by friction between the top of the box and the backfill soil or ground at the top of the box when the concrete box 4 is advanced, and is supported by the passive earth pressure of the ground in front of the retaining sheet piles 11 at the part where the retaining sheet piles 11 and the hanging beams 25 engage with each other at both ends of the entrance of the front of the starting shaft 8.

In addition, the following patent document shows that the friction-cut members are fixed to the reaction wall using tie rod members or hydraulic jacks so that they do not move together due to frictional resistance at the contact surface of the underground passage outer structure.
JP2008-144377Publication

In the conventional method shown in Figures 9 and 10, the tensile force due to the frictional resistance between the friction cut plate 23 and the box body, which is transmitted to the hanging girder 25 when the box body is advanced, is supported only by the engagement parts between the friction cut stopper 25 and the retaining sheet piles 11 at both ends of the tunnel mouth.

Therefore, there is concern that the retaining wall at the entrance of the tunnel may deform, causing a large impact on the surrounding ground. This impact is of particular concern when the starting shaft 8 is located close to houses, etc.

In addition, the number of tie rod members in the above-mentioned Patent Document 1 is large, which causes problems when suspending the concrete box into the starting shaft.

The object of the present invention is to provide a fixing device and method for a friction cut plate when advancing a concrete box, which eliminates the inconveniences of the above-mentioned conventional examples, prevents the movement of the friction cut plate that occurs when advancing a concrete box forward from the starting shaft without placing a burden on the starting shaft mouth, and has a simple structure so that it does not interfere with work inside the shaft.

To achieve the above objective, the present invention provides a fixing device for friction cut plates when driving a concrete box, which is constructed by installing a push jack in front of a bearing wall installed in the starting shaft and driving the concrete box with the push jack. The fixing device comprises a hanging beam that is laid horizontally on the ends of the friction cut plates that are parallel to each other and laid on the top surface of the concrete box, a support member that is placed between the bearing wall and the push jack, and a framework that connects the hanging beam and the support member.

The method of fixing the friction cut plate when driving a concrete box is to install a push jack in front of the bearing wall installed in the starting shaft, and when using this push jack to drive the concrete box, a fixing device consisting of a hanging beam that is laid horizontally on the ends of the friction cut plate that are parallel to each other on the top surface of the concrete box, a support member that is placed between the bearing wall and the push jack, and a framework that connects the hanging beam and the support member is used, and the friction cut plate is prevented from moving by the box driving reaction force transmitted to the rear end of the push jack when the push jack is extended.

According to the present invention, the rear end of the friction cut plate is engaged with a support member disposed between the bearing wall and the main jack via a hook girder, so that the friction cut plate can be prevented from moving due to the box thrust reaction force transmitted to the rear end of the main jack when the main jack is extended.

In addition, since it is made up of a framework that connects the hanging beams and the support members, it is not a large-scale facility, so there is less installation work required, fewer construction days, and less installation cost, making it economical.

In addition, the framework is installed in a way that leaves a sufficiently large opening in the center of the starting shaft, so there is no planar interference with the concrete box or the thrust jack inside the starting shaft, and there is no hindrance to the work of lowering the concrete box into the starting shaft, so work up and down the starting shaft can be carried out safely.

As described above, the fixing device and fixing method for the friction cut plate in the concrete box thrust of the present invention prevents the movement of the friction cut plate that occurs when thrusting the concrete box forward from the starting shaft without placing a burden on the starting shaft entrance, and because of its simple structure, it does not interfere with work inside the shaft.

FIG. 2 is a plan view showing one embodiment of a fixing device and fixing method for a friction-cut plate in a concrete box driving method of the present invention. FIG. 2 is a vertical cross-sectional side view showing one embodiment of a fixing device and fixing method for a friction-cut plate in a concrete box driving method of the present invention. 2 is a cross-sectional view taken along line AA in FIG. 1. 2 is a view taken along line BB in FIG. 1. FIG. 2 is an enlarged view of part C in FIG. FIG. 2 is an enlarged cross-sectional view of part C in FIG. FIG. 3 is an enlarged view of part E in FIG. 2 . FIG. 2 is a longitudinal sectional front view of a main portion showing one embodiment of a fixing device and fixing method for a friction-cut plate in a concrete box driving operation of the present invention. FIG. FIG. 11 is a vertical sectional side view showing a conventional example. FIG. 2 is a perspective view showing the open shield construction method.

The following describes in detail the embodiments of the present invention with reference to the drawings. Figure 1 is a plan view showing one embodiment of the fixing device and fixing method for friction cut plates in concrete box driving of the present invention, and in the figure, 8 indicates the starting shaft.

This starting shaft 8 is the starting shaft for the shield machine in the open shield method, which uses an open shield machine 1, which is a shield machine with openings on the front, back, and top, consisting of left and right side wall panels 1a and a bottom plate connected to these side wall panels 1a, as shown in Figure 11. The width of the open shield machine 1 is the same as the width of the concrete box 4 to be laid, and the tips of the side wall panels 1a and bottom plate are formed as cutting edges 2, and shield jacks 3 are arranged vertically facing backwards near the center or rear end of the side wall panels 1a.

The side wall of the cutting edge 2 is divided and movable to form a sliding retaining wall 17 to prevent the ground from collapsing on the side during excavation.

The departure shaft 8 is constructed using the steel sheet pile method, the parent pile horizontal sheet pile method, the liner plate method, etc., and is composed of retaining sheet piles 10 such as sheet piles and supports 12.

After the concrete box body 4 was installed in the designated position in the starting shaft 8, a push jack 14 was installed to propel the box body 4 forward, and a bearing wall 9 was installed to support the thrust reaction force of the box body 4 caused by the extension of the push jack 14.

The bearing wall 9 is made of steel materials arranged in a grid pattern, or unreinforced concrete is poured, and reinforced concrete is used if necessary. The push jack 14 is stored in a jack stand 27 formed by assembling steel materials.

Inside the starting shaft 8, smoothed concrete 19 was laid on top of the crushed stone foundation 20, and H-shaped steel beams were laid out on top of that in a rail-like shape, with a steel plate laid all over the top to form a support 18 for the installation and starting of the shield machine.

Although not shown in the figure, an open shield machine is installed inside the starting shaft 8 and advanced, and a concrete box body 4 is placed between the open shield machine and the base jack 14, and advanced by the base jack 14.

When pushing this concrete box 4, friction cut plates 23 are laid on the top surface of the concrete box 4 in a parallel arrangement, and the fixing device consists of a hanging beam 25 that is hung horizontally on the ends of the parallel friction cut plates 23, a support member 32 that is placed between the bearing wall 9 and the main push jack 14, and a framework that connects these hanging beams 25 and support members 32.

The hanging girder 25 is fixed to the friction cut plate 23 by a triangular locking flange 24 protruding from the friction cut plate 23. The hanging girder 25 is engaged with the retaining sheet pile 11.

The support members 32 are made of vertical bearing steel, which are arranged in pairs on the left and right so that they can engage with the vertically arranged main jacks 14. The framework is formed of steel girders 31, which are cross beams that span the support members 32, and connecting members 29 that connect the hanging girders 25 and the steel girders 31. The framework as a whole is in the shape of a square.

The connecting member 29 can be made of angle steel, channel steel, I-beam, etc., and both ends are fixed to the hanging beam 25 and steel beam 31 with connecting bolts and nuts 30.

The jack stand 27 on which the push jack 14 is placed and the support member 32 may be fixed together by welding or the like.

Next, we will explain how to use the fixing device of the present invention. When the concrete box 4 is advanced, the friction of the contact surface between the concrete box 4 and the friction cut plate 23 arranged on its upper surface tends to pull the friction cut plate 23 in the direction in which the concrete box 4 is advanced.

As a result, the hanging girder 25 engaged with the retaining sheet pile 11 also tries to be pulled, but the tensile force transmitted to the hanging girder 25 is supported by the backfill soil 5 via the retaining sheet pile 11, and the passive earth pressure from the backfill soil 5 resists as a reaction force.

In addition, the tensile force of the friction cut plate 23 is transmitted to the support member 32 via the framework of the hanging beam 25, connecting member 29, and steel beam 31, and the thrust reaction force that extends the push jack 14 and propels the concrete box 4 forward clamps the support member 32 between the bearing wall 9 and the jack stand 27, preventing the friction cut plate 23 from moving forward.

The larger the concrete box 4 and the greater the backfill soil coverage, the greater the frictional force between the friction cut plate 23 and the contact surface of the concrete box 4. However, since a large number of push jacks 14 are installed and the pushing pressure caused by the thrust reaction force transmitted to the steel girder 31 and support member 32 increases as the push jacks 14 extend, the friction cut plate 23 can be firmly fixed.

1...Open shield machine 1a...Side wall plate 2...Cutting edge 3...Shield jack 4...Concrete box body 5...Backfill soil 8...Starting shaft 9...Bearing wall 10...Retaining sheet pile 11...Mirror retaining sheet pile 12...Support 14...Head jack 17...Sliding retaining wall 18...Receiving base 19...Leveling concrete 20...Crushing stone foundation 23...Friction cut plate 24...Latching flange 25...Latching girder 27...Jack stand 28...Pithead steel 29...Connecting member 30...Connection bolt/nut 31...Steel girder 32...Support member

Claims (2)

When a base jack is installed in front of a bearing wall installed in a starting shaft and a concrete box is advanced using this base jack, a fixing device for friction cut plates in concrete box advancement is characterized by comprising a hanging beam that is hung horizontally on the end of a friction cut plate that is laid on the top surface of the concrete box and arranged in parallel, a support member that is placed between the bearing wall and the base jack, and a framework that connects the hanging beam and the support member. A method of fixing a friction cut plate in concrete box thrusting, characterized in that when a base jack is installed in front of a bearing wall installed in the starting shaft and a concrete box is thrusted using this base jack, a fixing device for the friction cut plate in concrete box thrusting, which comprises a hanging beam that is hung horizontally on the end of a friction cut plate that is laid in parallel on the top surface of the concrete box, a support member that is placed between the bearing wall and the base jack, and a framework that connects these hanging beams and support members, is used, and the friction cut plate is prevented from moving due to the thrust reaction force of the concrete box transmitted to the rear end of the base jack when the base jack is extended.

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