Method for preventing displacement of concrete box structures used in open shield tunneling and for fixing and releasing the displacement.

Abstract

To provide a displacement prevention fixing and releasing method for concrete box body for open shield method, which uses a light-weight member capable of being easily, simply and safely installed and removed by an operator.SOLUTION: Curve-shaped sheath holes 33 are installed from haunch faces 43 on four corners of concrete box bodies 4 to be connected so as to continue at connection end faces. A semicircular curve shaped pin 32 is inserted from an opening of one sheath hole 33 so as to make both ends of the pin protrude from the haunch faces 43 and prevent displacement at the connection end faces between the concrete box bodies 4. When displacement prevention becomes unnecessary, the semicircular curve shaped pin 32 is removed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a structure for preventing displacement of a flexible concrete casing used in an open shield method for constructing underground structures such as sewers and subways in urban areas.

Background Art

[0002] The open shield method is a highly rational method that combines the advantages of the excavation method (open cut method) and the shield method. Its outline is explained in FIGS. 9 to 13.

[0003] In the figure, reference numeral 1 denotes an open shield machine, which is a shield machine having a front, a rear, and an upper surface that are open and composed of left and right side wall plates 1a and a bottom plate 1b connecting these side wall plates 1a.

[0004] The open shield machine 1 forms the tips of the side wall plates 1a and the bottom plate 1b as cutting edges 2, and propulsion jacks 3 are arranged vertically side by side facing backward near the center or the rear end of the side wall plates 1a.

[0005] Furthermore, the open shield machine 1 divides the machine body into a front machine 17 and a tail machine 18 in the front-rear direction, and the front end of the tail machine 18 is fitted into the rear end of the front machine 17 to form a middle bending portion 51 at the mutual fitting portion so that it can be bent. A middle bending jack is arranged at this middle bending portion 51.

[0006] The front machine 17 mainly serves as an excavation part, and the tail machine 18 arranges the propulsion jacks 3 and serves as a tail part 19 as a hoisting and installing part of the concrete casing 4.

[0007] In the figure, reference numeral 16a denotes a slide earth retaining plate provided at the front end of the front machine 17, and reference numeral 23 denotes a press bar (press corner) using an H-shaped steel material or the like. Reference numeral 52 denotes a rear earth retaining plate when the concrete casing 4 comes out of the tail machine 18 as the open shield machine 1 advances, and the upper part of the concrete casing 4 is backfilled inside this rear earth retaining plate.

[0008] As shown in Figure 10, the open shield machine 1 is assembled in a predetermined position in the launch shaft 8. After assembly, the propulsion jacks 3 of the open shield machine 1 are extended to take reaction force from the reaction wall 9 in the launch shaft, and the open shield machine 1 is advanced. The first concrete box 4 that will form the underground structure is lowered from above and set behind the retracted propulsion jacks 3 in the tail section 19 of the open shield machine 1.

[0009] The concrete box bodies 4, which are laid sequentially within the launch shaft 8, are propelled forward by the open shield machine 1, and after exiting the launch shaft 8, they are propelled to a predetermined distance and temporarily laid as reaction force transmission materials until the propulsion force of the open shield machine is no longer transmitted to the reaction wall 9 within the launch shaft 8. They are removed when the propulsion reaction force is no longer transmitted to the reaction wall 9.

[0010] The launch shaft 8 is retained by an earth retaining wall 27, and a portion of this front earth retaining wall is cut to launch the open shield machine 1. Additionally, if necessary, ground improvement 11 may be applied to the front portion of the launch shaft 8 by grout injection or other means.

[0011] Next, after cutting a portion of the retaining wall in front of the launch shaft 8, the soil in front of the open shield machine 1 is excavated from above using an excavating machine 6 such as a shovel and removed.

[0012] Simultaneously with or after this soil removal process, the propulsion jack 3 is extended to advance the open shield machine 1 while generating propulsion reaction force on the concrete box body inside the tail section 19 and the concrete box body connected behind it. In this advancement process, a press bar (press angle) 23 made of a frame using box steel or shaped steel is placed in front of the concrete box body 4.

[0013] Then, after the open shield machine 1 moves forward by the length of one concrete box, the second concrete box 4 is lowered and set into the tail section 19 of the open shield machine 1 in front of the first concrete box 4 using the lifting machine 24.

[0014] The following excavation and soil removal processes, advancement processes, and concrete box structure 4 setting processes are repeated as appropriate, and the concrete box structures 4 are sequentially left in the ground in a vertical line as the open shield machine 1 advances. As shown in Figure 13, the top surface of the concrete box structures 4 is backfilled and the surface is paved.

[0015] In addition, although not shown in the diagram, during the setting process for the concrete box 4, after the concrete box 4 is set inside the tail machine, the backfill grout is injected as a primary injection, and then the backfill grout is injected as a secondary injection to fill the voids that occur in the ground during the excavation, soil removal, and forward movement processes of the open shield machine 1.

[0016] Therefore, once the open shield machine 1 reaches the receiving tunnel 13, it will be removed and the construction will be completed.

[0017] The concrete box body 4 is made of reinforced concrete and is a single rectangular structure consisting of a left slab, a right slab, a top slab, and a bottom slab, with the front and rear surfaces open. In addition, pre-installed grout holes are provided near the center of each of the left and right slabs and the bottom slab. Through these grout holes, as described above, the backfill grout material is injected and filled into the tail void that is generated in the ground after the concrete box body 4 is installed in the tail section 19 and as the open shield machine 1 excavates, as primary and secondary injections, respectively.

[0018] Incidentally, the concrete box body 4 is connected to the aforementioned concrete connecting end faces by installing flexible members with predetermined seismic resistance, thereby providing seismic resistance. When the open shield machine 1 excavates, it extends the shield jacks 3 and takes a propulsive reaction force on the concrete box body 4 in the tail section 19 and the subsequent concrete box body 4 connected thereto, as the open shield machine 1 moves forward. Therefore, it is necessary to fix the flexible concrete box body 4 so that no displacement occurs between the connecting end faces.

[0019] Furthermore, during the propulsion of the open shield machine 1, the shield machine 1 is affected by the resistance of the ground at the face of the shield machine 1 and the frictional resistance between the side plates 1a and the bottom plate 1b of the shield machine 1 and the ground in contact with it, causing the shield machine 1 to oscillate slightly up and down and left and right as it propels forward. At this time, depending on the type of soil, deposition conditions, and partial hardness of the ground in the cross-sectional direction of the ground at the face of the shield machine 1, as well as the complex soil deposition conditions of the ground in the direction of propulsion, the amount of meandering of the shield machine 1 in the vertical and horizontal cross-sectional directions may increase.

[0020] It is necessary to propel the shield machine while controlling its meandering, and to do this, multiple propulsion jacks 3, which are arranged symmetrically with respect to the cross-section of the shield machine, are used asymmetrically to control the meandering. However, an uneven load acts on the concrete box bodies that have already been laid behind it. As a result, a shear force is generated that tends to cause displacement between the connecting end faces of the laid box bodies.

[0021] For the reasons described above, in order to prevent displacement between the connecting end faces of the flexible concrete box bodies 4 when the shield machine is propelled, it is common practice to install anti-slip steel members 28 as shown in Figures 14 to 17 to restrain the concrete box bodies 4 from one another.

[0022] These anti-slip steel members 28 are made of structural steel and are bolted to the concrete box body 4 using bolt holes 29 and bolts 30.

[0023] Patent Document 1 below shows that when a flexible box culvert is pushed into the ground from a launching shaft by a pipe jacking method, X-shaped anti-sway fittings are installed between the connecting end faces on the inner surface of the concrete box to prevent twisting and displacement of the box culvert due to the jacking process.

[0024] Furthermore, Patent Document 2 below shows that the connections between the segments in the circumferential direction of the segments used to construct a circular tunnel by the shield tunneling method are made with bent bolts.

[0025] When the shield machine is tunneling, both ends of the bent bolt are tightened with nuts or the like so that there is no opening between the connecting end faces of the piece segments due to the tunneling thrust of the shield machine or misalignment (step) between the segments in the tunnel extension direction. In other words, by tightening the bent bolt, the circular shape in the circumferential direction of the segments during tunneling after assembling each segmented segment is maintained. And when the tunneling thrust acting on the segments is out of the affected range, the bent bolt is removed.

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0026] The anti - displacement steel material 28 as shown in FIGS. 14 to 17 above and the invention of the anti - snake - like fitting of Patent Document 1 use large steel materials, so the weight is large.

[0027] Also, when transporting from inside the already laid flexible concrete casing behind the open - shield machine to the installation location of the anti - displacement steel material, the longer the laying distance of the already laid flexible concrete casing, the longer the transportation time required. Moreover, since the transportation weight is heavy, transportation equipment is also required.

[0028] Furthermore, when the anti - displacement steel material is dropped from above the tail part of the open - shield machine, since the anti - displacement steel material is also a large heavy object, it becomes an up - and - down operation of dropping with a hoist or the like, so it is necessary to give sufficient consideration to safety.

[0029] In addition to this, when installing the above - mentioned anti - displacement steel material or the anti - snake - like fitting of Patent Document 1 in the flexible concrete casing, the smaller the inner space of the flexible concrete casing, the narrower the working space for the installer's installation work, so the installation work becomes extremely difficult.

[0030] Furthermore, the larger the flexible concrete box is and the larger its internal cross-section, and the heavier it becomes, the more difficult it becomes for workers to install the top slab and upper side walls on the inside of the flexible concrete box.

[0031] Furthermore, the aforementioned anti-slip steel materials and anti-sway fittings are fixed to the inner surface of the flexible concrete box body with pre-installed hole-in anchors and bolts, but the large number of bolts required makes the installation work time-consuming.

[0032] Furthermore, the more anchors are installed, the higher the installation precision required for the orientation and spacing of the hole-in anchors. Poor installation precision can prevent the bolts from being properly inserted into the hole-in anchors, resulting in areas where the bolts do not function adequately.

[0033] Therefore, if the amount of meandering control during construction using the open shield machine or the jacking method described in Patent Document 1 becomes large, depending on the usage of the jacking jacks, an uneven load may be applied to the flexible concrete box, and the shear force that tries to cause displacement between the connecting end faces of the flexible concrete box will increase. As a result, excessive shear force may be applied to some bolt installation locations, and there is a risk that defects such as cracks may occur in the concrete near those locations.

[0034] As mentioned above, Patent Document 2 describes a method for constructing a tunnel using the shield tunneling method in which, when a divided piece segment is assembled in a circular shape, the connecting end faces between the piece segments are fastened with curved bolts, and the curved bolts are removed when the effects such as gap opening caused by the thrust force acting on the segment during shield machine excavation have disappeared. However, it does not show how to remove them.

[0035] The object of the present invention is to eliminate the disadvantages of the conventional method and to provide a method for fixing and releasing the displacement of concrete box bodies for open shield construction that can be easily, simply, and safely installed and removed by workers using a lightweight displacement prevention material. [Means for solving the problem]

[0036] To achieve the above objective, the present invention as described in claim 1 involves installing curved sheath holes continuously from the haunch surfaces at each of the four corners of the connecting concrete box bodies to the connecting end faces, inserting a curved pin, with both ends protruding from the respective haunch surfaces, through one of the sheath hole openings to prevent slippage at the connecting end faces between the concrete box bodies, and removing the curved pin by pushing or pulling it out when the need for slippage prevention is eliminated.

[0037] According to the present invention as described in claim 1, by installing curved pins at the four corners between the connecting end faces of the connected box bodies, the connection end faces are fixed together against displacement in the cross-sectional direction. Therefore, even if the thrust reaction force is applied asymmetrically to the flexible concrete box body immediately behind the thrust jack due to meandering correction during excavation by an open shield machine, the pins will not slip or come out of the sheath hole, and no displacement of the concrete box bodies will occur between the connecting end faces.

[0038] Furthermore, since the ends of the curved pins protruding from each of the haunch surfaces are not fastened or fixed with nuts, the problem of "stress at the joint concentrating in the bolt insertion hole and causing premature cracking in the concrete wall of the insertion hole" that occurs with fastening curved bolts with nuts does not occur, as described in the reference document of Patent Document 2 mentioned above.

[0039] Furthermore, the anti-slip mechanism using curved pins is significantly lighter than steel, and since it does not require fastening and fixing the anti-slip steel material between connecting end faces with numerous bolts and nuts or pre-installed hole-in anchors in the concrete box, workers can perform the work easily and simply.

[0040] Furthermore, since the anti-slip structure is only at the haunches at the four corners of the concrete box body, the sheath holes can be installed with high precision.

[0041] Since the curved pin can be removed by pushing or pulling it out, removal can be done easily and reliably when the need for preventing slippage is no longer present.

[0042] The present invention as described in claim 2 is a curved pin with a semicircular curve shape, and the extrusion and removal of this curved pin is performed from the sheath hole on one side. Curvature of a semicircular curved pin The gist of this method is to insert a pin with the same radius of curvature as the axis of the curved pin, and then push out and remove the curved pin.

[0043] According to the present invention as described in claim 2, a semicircular curved pin can be pushed out of the sheath hole by placing another pin with the same curved shape as the semicircular curved pin against one end of the semicircular curved pin and striking the pin with a hammer or the like. This makes the removal work easier.

[0044] The present invention as described in claim 3 is characterized in that the curved sheath hole is connected to the short straight sheath holes in the haunches at each of the four corners on the inner surface of the other concrete box body to be connected, the curved pin is a bolt with a short straight end, and the removal of the curved pin is performed by inserting a wedge plate that clamps the bolt between the bolt head and the surface of the haunch where the bolt is inserted.

[0045] According to the present invention as described in claim 3, the curved pin is a bolt with a short straight end that is inserted between the connecting end faces of the haunches at the four corners of the inner surface of the connecting flexible concrete box bodies, making insertion into the sheath hole easy.

[0046] Furthermore, when removing the bolts, a wedge plate can be inserted between the protruding bolt and the concrete surface to facilitate removal. [Effects of the Invention]

[0047] As described above, the method for fixing and releasing the displacement of concrete box bodies for open shield construction according to the present invention uses a lightweight displacement prevention material that can be easily, simply, and safely installed and removed by workers. [Brief explanation of the drawing]

[0048] [Figure 1] This is a perspective view showing a first embodiment of the method for preventing displacement of a concrete box structure for open shield construction according to the present invention. [Figure 2] This is a perspective view of the main part showing the first embodiment of the method for fixing and releasing displacement of a concrete box body for open shield construction according to the present invention. [Figure 3] This is a longitudinal cross-sectional side view showing a first embodiment of the method for fixing and releasing displacement of a concrete box for open shield construction according to the present invention. [Figure 4] This is a perspective view showing the removal of pins in the first embodiment of the method for fixing and releasing slippage of a concrete box body for open shield construction according to the present invention. [Figure 5] This is a perspective view showing a second embodiment of the method for fixing and releasing displacement of a concrete box for open shield construction according to the present invention. [Figure 6] This is a longitudinal cross-sectional side view showing a second embodiment of the method for fixing and releasing displacement of a concrete box for open shield construction according to the present invention. [Figure 7] This is a perspective view of a key part showing a second embodiment of the method for preventing displacement of a concrete box structure for open shield construction according to the present invention. [Figure 8] This is a perspective view showing the removal of pins in a second embodiment of the method for fixing and releasing slippage of a concrete box body for open shield construction according to the present invention. [Figure 9] This is a perspective view showing the construction status of the open shield tunneling method. [Figure 10] This is a side view showing the first step of the open shield tunneling method. [Figure 11] This is a side view showing the second step of the open shield tunneling method. [Figure 12] This is a side view showing the third step of the open shield tunneling method. [Figure 13] This is a side view showing the fourth step of the open shield tunneling method. [Figure 14] This is a cross-sectional plan view showing a conventional example. [Figure 15]This is a longitudinal cross-sectional view showing a conventional example. [Figure 16] This is a longitudinal cross-sectional view showing a conventional example. [Figure 17] This is a front view of the main section in a conventional example. [Modes for carrying out the invention]

[0049] The embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a perspective view showing the first embodiment of the method for fixing and releasing displacement of a concrete box for open shield construction according to the present invention, Figure 2 is a perspective view of the main part of the same, and Figure 3 is a longitudinal cross-sectional side view of the same. The general construction of the open shield method is the same as described above, so it will be omitted here.

[0050] In the figure, 43 is the haunch surface of the haunch portion on the inner surface of the concrete box body 4. Curved sheath holes 33 are continuously installed from the haunch surfaces 43 at each of the four corners of the connecting concrete box bodies 4 to the connecting end faces. The sheath holes 33 are sheath holes with a quarter-circular curve shape.

[0051] The sheath hole into which the semicircular curved pin 32 described later is inserted is provided as a quarter-circular curved sheath hole 33, extending from a position close to the connecting end face on the inner surface of one of the casings to the surface of the connecting end face.

[0052] Furthermore, the other concrete box body also has a sheath hole 33 installed in the same way, and in the connected concrete box body 4, both sheath holes 33 are continuous as semicircular curved sheath holes between the connecting end faces.

[0053] The curved pin inserted into the sheath hole 33 from the opening is a semicircular curved pin 32, and the end of the semicircular curved pin 32 inserted from one of the sheath holes 33 openings protrudes from each of the haunch surfaces 43.

[0054] The semicircular curved pins 32 are fully inserted into the interior of both connected concrete box bodies 4 from the four corner haunch surfaces 43 located close to the connecting end faces on the inner surfaces of the connected flexible concrete box bodies. Therefore, since the four corners are fixed, the connection end faces are fixed together, and no displacement occurs between the connection end faces in the left-right or up-down directions.

[0055] The semicircular curved pin 32 can be easily inserted by hand into the semicircular curved sheath hole by a worker.

[0056] To remove the semicircular curved pin 32, a curved ejector pin 34 is brought into contact with one end of the semicircular curved pin 32, and the semicircular curved pin 32 is pushed out through the curved ejector pin 34 using a hammer.

[0057] As a second embodiment of the present invention, as shown in Figures 5 to 7, the sheath hole is provided in the form of a quarter-circular curved sheath hole 37, extending from a haunch surface 43 located near the connecting end face on the inner surface of one of the concrete box bodies 4 to the surface of the connecting end face.

[0058] Furthermore, the other concrete box body 4 has a short, straight sheath hole 38 extending inward from its connecting end face, and the sheath hole 37 and the sheath hole 38 are continuous between the connecting end faces of the connected flexible concrete box bodies 4.

[0059] The curved pin inserted into the sheath hole is a bolt 36 with a semicircular curve shape, which is formed by a semicircular curved portion and a short straight portion on one side that is shorter than the semicircular curved portion. The head of the semicircular curved portion is threaded and a nut 39 is inserted into it.

[0060] The aforementioned semicircular curved bolt 36 is installed so that it is fully embedded inside both concrete box bodies 4 through the connection end faces, with the four corner haunch surfaces 43 located close to each other between the connecting end faces on the inner surfaces of the connected concrete box bodies 4.

[0061] The aforementioned semicircular curved bolt 36 has a short straight section that is continuous from the end of the semicircular curved section, and is inserted into a continuous sheath hole consisting of the continuous sheath hole 37 and sheath hole 38. In this case, the concrete box body 4 to be connected may be opened slightly, the short straight section of the semicircular curved bolt 36 may be inserted first, and then the concrete box body 4 may be joined together. In this way, the semicircular curved bolt 36 can be easily inserted by hand by a worker.

[0062] Therefore, since the connection end faces are fixed together by installing the bolts 36 at the four corners, no misalignment occurs between the connection end faces in the left-right or up-down directions.

[0063] To remove the semicircular curved bolt 36, a nut 39 is placed on the threaded portion, and a wedge plate 40 is inserted between the nut and the haunch surface at the bolt insertion position to clamp the semicircular curved bolt 36.

[0064] The wedge plate 40 has a slit notch 40a in the center into which a bolt 36 with a semicircular curve shape on one side fits. By pushing this notch with a hammer or the like and gradually loosening the nut 39 to shift its position, the bolt 36 with a semicircular curve shape on one side can be pulled out.

[0065] Furthermore, the bolt 36 with a semicircular curve shape on one side is formed by a short straight section that is shorter than the semicircular curve shape. If this short straight section comes out of the short straight sheath hole 38 of the other concrete box body 4, the locking mechanism to prevent the concrete box bodies 4 from shifting is released. [Explanation of Symbols]

[0066] 1…Open shield aircraft 1a...Side wall plate 1b...Bottom plate 2…Blade opening 3…Propulsion jack (shield jack) 4...Concrete box structure 5...Backfill 6…Excavator 7…Dump truck for removing excavated soil 8…Launch shaft 9…Reaction wall 10... Heavy machinery for backfilling 11... Ground improvement 13...reaching hole 14...PC steel rod 15... Dump truck for backfilling 16a... Sliding earth retaining plate 17...Front unit 18...Tail unit 19...Tail section 21...Backfill injection plant 23... Press bar (pressing bar) 24... Lifting machine 25... Backfill injection material 27... Retaining wall 28... Anti-slip steel material 29... Bolt hole 30... Bolt 31... Hole-in anchor 32...Semicircular curved pin 33...Sheath hole 34...Curved-shaped ejection pin 35...Hammer 36…Bolt with a semicircular curved shape on one side 37…Sheath hole 38...Sheath hole 39...Nut 40...Wedge plate 40a...Slit notch 43...Haunch surface 51...Folded section

Claims

1. A method for fixing and releasing slippage prevention for concrete box bodies in an open shield construction method, characterized by installing curved sheath holes continuously from the haunch surfaces at each of the four corners of the connected concrete box bodies to the connecting end faces, inserting curved pins with both ends protruding from the respective haunch surfaces through one of the sheath hole openings to prevent slippage at the connecting end faces between the concrete box bodies, and removing the curved pins by pushing or pulling them out when slippage prevention is no longer necessary.

2. The method for fixing and releasing a concrete box body for open shield construction according to claim 1, wherein the curved pin is a semicircular curved pin, and the removal of the curved pin is performed by inserting a pin with the same radius of curvature as the axis of the curved pin of the semicircular curved pin through a sheath hole on one side, and pushing out the curved pin to remove it.

3. A method for fixing and releasing a concrete box for open shield construction that prevents displacement, according to claim 1. The curved sheath hole is connected to the short straight sheath holes in the haunches at each of the four corners on the inner surface of the other concrete box to be connected, the curved pin is a bolt with a short straight end, and the removal of the curved pin is performed by inserting a wedge plate that clamps the bolt between the bolt head and the surface of the haunch at the bolt insertion position.

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