Shoring unit and shoring assembly method

Abstract

To provide: a shoring unit which comprises a tie member and steel shoring and can improve both workability and safety during shoring construction; and a shoring assembly method based on the shoring unit.SOLUTION: A shoring unit 3 comprises: steel shoring 4 formed from a pair of flanges 41, 41 and a web 42 laterally spanning between the pair of flanges 41, 41; a tie member 5 fixed to a pit mouth side surface of the web 42; a mounting member 7 provided at a pit mouth end of the tie member 5; and a receiving member 6 that is engageable with a mounting member 7 and laterally spans between excavation face ends of the pair of flanges 41, 41 at a position corresponding to the tie member 5.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a shoring unit and a shoring assembly method using the shoring unit. [Background technology]

[0002] In tunnel construction using NATM, the ground surface exposed by tunnel excavation is sealed off early with shoring. Tunnel shoring generally consists of shotcrete sprayed onto the ground surface, steel shoring assembled along the ground surface, and rock bolts driven into the ground normal to the tunnel from inside.

[0003] When assembling steel shoring, it is common to use heavy machinery such as an erector to hold the steel shoring, place the left and right steel shoring near the top of the face, and then manually tighten the bolts. However, tightening bolts manually is time-consuming and requires that the work be done on the exposed ground before the shoring is completed, or directly under the first shotcrete.

[0004] For this reason, construction methods aimed at improving workability and safety during construction of shoring have been disclosed.For example, Patent Document 1 discloses a tunnel construction method in which a male connector is provided at an end (joint) of one of a pair of left and right steel shoring, and a female connector is formed at an end (joint) of the other steel shoring, and an erector device having a pair of hands capable of holding the steel shoring is used to butt the joints of the left and right steel shoring together to engage the male connector with the female connector, and then the steel shoring assembled in an arch shape is erected along the face of the tunnel.

[0005] The steel shoring must be connected to the existing steel shoring (the shoring adjacent to the tunnel mouth side) via tie materials to prevent it from falling over. Generally, the sheath tube method and the tie rod method are used for such tie materials. The sheath tube method connects the front and rear steel shoring by inserting a hook formed at the tip of a tie material made of a steel rod into a sheath tube fixed to the steel shoring (see Patent Document 2, for example). The tie rod is installed horizontally between the steel shoring as a tie material, and a nut is fastened to the end of the tie rod that passes through the web of the steel shoring. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6374051 [Patent Document 2] Patent Publication No. 2021-67136 Summary of the Invention [Problem to be solved by the invention]

[0007] The work of installing ties is generally done manually between new and existing steel supports. Therefore, even if the tunnel construction method described in Patent Document 1 is adopted, workers must enter the exposed ground before the shoring is completed or directly under the primary shotcrete to install the ties. Furthermore, installing ties manually is time-consuming.

[0008] The present invention aims to propose a shoring unit comprising connecting materials and steel shoring, which makes it possible to improve workability and safety during shoring construction, and also to propose a shoring assembly method using this shoring unit. [Means for solving the problem]

[0009] The support unit of the present invention, which solves such problems, comprises a steel support consisting of a pair of flanges and a web spanning the pair of flanges, a tie fixed to the side of the web at the mouth of the tunnel, an attachment member provided at the mouth side end of the tie, and a receiving member engageable with the attachment member spanning the face side ends of the pair of flanges at a position corresponding to the tie.

[0010] The shoring assembly method of the present invention also includes an erection step of erecting the shoring unit near the face, and a connection step of connecting the shoring unit to another shoring unit provided on the tunnel mouth side via the tie material. In the connection step, the shoring unit is pulled toward the other shoring unit, and the mounting members of the shoring unit are engaged with the receiving members of the other shoring unit.

[0011] According to this shoring unit and shoring assembly method, the tie members can be easily connected to the existing steel shoring (existing shoring unit) simply by engaging the mounting members with the receiving members. Therefore, even when assembling the steel shoring using heavy machinery, workers do not need to enter the exposed ground before the shoring is completed or directly under the primary shotcrete in order to install the tie members.

[0012] The mounting member may comprise a base fixed to the end of the connecting material via a fixing member, a pair of horizontal parts extending from both ends of the base toward the mine mouth, and a pair of guide parts extending from the tips of the pair of horizontal parts toward the face side. In this case, the pair of guide parts are inclined with respect to the horizontal parts so that the tips approach each other toward the face side, and the receiving member is a steel rod that can be inserted into the space surrounded by the base and the tips of the pair of guide parts. In this case, it is preferable that the connecting material is a steel pipe with a nut fixed to the mine mouth end, and the fixing member is a bolt with the base welded to the head and screwed into the nut.

[0013] In this way, when the shoring unit is pulled toward the tunnel mouth, the support member is guided by the guide section toward the tip of the guide section, and then inserted into the space surrounded by the base section and the tips of the pair of guide sections, so that the mounting member and the support member are engaged. Therefore, simply by pulling the shoring unit toward the existing shoring unit, it is possible to connect the shoring units to each other. Effect of the Invention

[0014] According to the shoring unit of the present invention and the shoring assembly method using the same, it is possible to improve workability and safety during shoring construction. [Brief description of the drawings]

[0015] [Figure 1] 1A and 1B are diagrams showing an overview of a tunnel according to an embodiment of the present invention, in which (a) is a cross-sectional view and (b) is a longitudinal section view. [Diagram 2] FIG. 2 is a diagram showing a support unit of the first embodiment, in which (a) is a cross-sectional view and (b) is a cross-sectional view viewed from a direction perpendicular to (a). [Diagram 3] FIG. [Figure 4] 1(a) to 1(d) are diagrams showing the connecting process of the support assembly method. [Diagram 5] 11A and 11B are diagrams showing a support unit of the second embodiment, in which (a) is a cross-sectional view, (b) is a cross-sectional view viewed from a direction perpendicular to (a), (c) is a front view of a rotation stop member, (d) is a front view of a mounting member, and (e) is a plan view of a guide member. [Figure 6] 1(a) and 1(b) are cross-sectional views showing examples of the receiving member. [Figure 7] FIG. 1 shows a view plate, where (a) is a side view and (b) is a front view. [Figure 8] 6(a) to 6(d) are diagrams showing a connecting process of the support assembling method of the second embodiment. [Figure 9] 13A and 13B are cross-sectional views showing the connecting process of the support assembly method of the second embodiment, and FIG. 13D are front views seen from the tunnel mouth side. [Figure 10] 10A, 10B, and 10C are diagrams showing a connecting step following FIG. 9, in which (a) is a cross-sectional view, (b) is a front view seen from the wellhead side, and (c) is a side view. [Figure 11] 11A and 11B are diagrams showing another form of support unit, in which (a) is a cross-sectional view and (b) is a cross-sectional view viewed from a direction perpendicular to (a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] First Embodiment In the first embodiment, a case where a tunnel is constructed by NATM will be described. As shown in Fig. 1(a) and (b), a tunnel T is stabilized by blocking the exposed natural ground surface Gs by excavating the natural ground G with supports 1 made of sprayed concrete 2 and steel supports 4. In addition, auxiliary construction methods such as forepoling (short-length pre-supporting work), head bolt work, and leg reinforcement work may be used in combination during tunnel construction as necessary.

[0017] In tunnel construction, first, the natural ground G is excavated to form a borehole (tunnel T). The excavation method for the tunnel T is not limited, and may be, for example, blasting excavation or mechanical excavation. The excavation length of the tunnel T per cycle is determined according to the natural ground conditions (natural ground grade, earth covering, etc.), but in this embodiment, it is 1.0 to 1.2 m.

[0018] After the tunnel T is excavated to a predetermined length (1.0 to 1.2 m in this embodiment), the ground G is excavated and the support structure 1 is formed along the exposed ground surface Gs (see FIG. 1). The construction of the support structure 1 includes a primary spraying work, erection work, and a secondary spraying work (spraying work).

[0019] In the primary spraying work, primary shotcrete 21 is sprayed onto the natural ground surface Gs exposed by excavation of the natural ground G. The primary shotcrete 21 is sprayed onto the wall surface (side surface) of the tunnel T as well as the face K. The spraying thickness of the primary shotcrete 21 may be determined appropriately, and may be, for example, 5 cm.

[0020] In the erection work, a shoring unit 3 is erected near the face K. The shoring unit 3 comprises a steel shoring 4, a connecting member 5, and a receiving member 6. In the erection work, a pair of left and right steel shoring 4, 4 are connected at the top to form an arch shape. When erecting the shoring unit 3, an installation process, an erection process, and a connection process are performed.

[0021] In the installation process, as shown in Fig. 2, a tie material 5 is attached to a steel support 4 to form a support unit 3. As shown in Fig. 3, the steel support 4 is formed by processing a so-called H-shaped steel consisting of a pair of flanges 41, 41 and a web 42 horizontally disposed across the pair of flanges 41, 41. In the steel support 4, receiving members 6 are welded to the flanges 41, 41 corresponding to the attachment points of the tie material 5, and bolt insertion holes 43 are formed in the web 42.

[0022] The tie member 5 is a member that connects the steel supports 4 arranged at the front and rear (see FIG. 1(b)), and is laid horizontally between the steel supports 4 arranged at the front and rear. In this embodiment, the tie member 5 is fixed with its tip (the end on the face K side) in contact with the web 42 of the steel support 4. The tie member 5 is fixed to the side of the web 42 at the pit mouth. The tie member 5 is made of a steel pipe, and a nut 51 is welded to the inner hollow part at the tip of the tie member 5 (see FIG. 2). As shown in FIGS. 2(a) and (b), the tie member 5 is fixed to the steel support 4 by fastening the bolt 52 that penetrates the web 42 to the nut 51. In addition, a nut 75 for fixing the mounting member 7 is also welded to the inner hollow part at the base end of the tie member 5 (the inner hollow part at the pit mouth side end).

[0023] An attachment member 7 is provided at the base end (the end on the wellhead side) of the connecting material 5. The attachment member 7 is formed by processing a steel rod, and is fixed to the end of the connecting material 5 via a fixing member 74. The attachment member 7 includes a base 71 fixed to the fixing member 74, a pair of horizontal parts 72, 72 extending from both ends of the base 71 towards the wellhead side, and a pair of guide parts 73, 73 extending from the tips of the pair of horizontal parts 72, 72 towards the face side.

[0024] The pair of guide portions 73, 73 are inclined with respect to the horizontal portions 72, 72 so that the tips approach each other toward the face side. The tips of the guide portions 73 are in contact with each other or are close to each other with a gap smaller than the diameter of the receiving member 6. In addition, the tips of the guide portions 73 are close to the base portion 71.

[0025] The fixing member 74 is a bolt having a head portion welded to a base portion 71. The mounting member 7 is fixed to the base end of the connecting member 5 by screwing the fixing member 74 into a nut 75.

[0026] 2(a) and (b), the receiving member 6 is horizontally disposed on the face side ends of the pair of flanges 31, 31 at a position corresponding to the connecting member 5. The receiving member 6 is a steel rod that can be inserted into the space surrounded by the base portion 71 and the tips of the pair of guide portions 73, 73, and is welded to the end faces of the pair of flanges 31, 31 as shown in FIG.

[0027] The connection material 5 is attached to the steel support 4 by first placing the connection material 5 on the face K side of the web 42 of the steel support 4 and inserting the bolt 52 into the bolt insertion hole 43 formed in the web 42. Then, the bolt 52 is screwed into the nut 51 to attach the connection material 5 to the steel support 4.

[0028] In the erection process, the steel supports 4 to which the connecting materials 5 are fixed are erected near the face K along the surface of the primary shotcrete 21 (or the ground surface Gs). At this time, as shown in FIG. 1(a), a pair of left and right steel supports 4, 4 are assembled in an arch shape by connecting them at their tops.

[0029] In the connection process, as shown in Fig. 4, a tie member 5 fixed to a steel support (new steel support) 4 is connected to an existing steel support 4a installed on the tunnel mouth side. The tie member 5 is connected to the existing steel support 4a by engaging an attachment member 7 with a receiving member 6 fixed to the existing steel support 4a.

[0030] In the connecting process, as shown in Figs. 4(a) and (b), first, the steel support 4 is pulled toward the existing steel support 4a, and the mounting member 7 is brought close to the receiving member 6. At this time, the mounting member 7 is inserted into the space surrounded by the pair of flanges 41, 41 and the web 42 of the existing steel support 4a. When the steel support 4 is pulled, the receiving member 6 and the guide portion 73 of the mounting member 7 come into contact with each other, and the receiving member 6 is guided toward the tip side of the guide portion 73. Then, when the steel support 4 is further pulled toward the existing steel support 4a, the receiving member 6 enters between the tips of the pair of guide portions 73, 73, as shown in Figs. 4(c) and (d), and then the receiving member 6 enters into the space surrounded by the tips of the pair of guide portions 73, 73 and the base portion 71, and the mounting member 7 and the receiving member 6 are engaged with each other.

[0031] After the steel support 4 is connected to the existing steel support 4a by the connecting material 5, the secondary shotcrete 22 is sprayed toward the side of the tunnel T (see FIG. 1(b)).

[0032] According to the shoring unit 3 and shoring assembly method of this embodiment, the tie material 5 can be easily connected to the existing steel shoring 4a (existing shoring unit 3) simply by engaging the mounting member 7 with the receiving member 6. Therefore, even when the steel shoring 4 is assembled using heavy machinery, there is no need for workers to enter the exposed ground before the shoring is completed or directly below the primary shotcrete 21 in order to install the tie material 5.

[0033] Furthermore, the support unit 3 has a simple structure and is constructed by combining relatively easily available parts, so that manufacturing costs can be kept low. Since the mounting member 7 is made of a steel rod, it is easy for the mounting member 7 to enter between the flanges 41 of the existing steel support 4a, and the mounting member 7 is unlikely to come into contact with the existing steel support 4a. Therefore, when the connecting material 5 is connected to the existing steel support 4a, damage to the mounting member 7 can be suppressed.

[0034] Second Embodiment In the second embodiment, a case where a tunnel is constructed by NATM will be described as the same as in the first embodiment. The tunnel T is stabilized by blocking the exposed natural ground surface Gs by excavating the natural ground G with supports 1 made of sprayed concrete 2, steel supports 4, etc. (see FIG. 1).

[0035] In tunnel construction, first, the natural ground G is excavated to form a borehole (tunnel T). After the tunnel T has been excavated to a predetermined length (1.0 to 1.2 m in this embodiment), the support structure 1 is formed along the natural ground surface Gs exposed by excavating the natural ground G. The construction of the support structure 1 includes primary spraying work, erection work, and secondary spraying work (spraying work). Note that the details of the primary spraying work and the secondary spraying work are similar to those in the first embodiment, and therefore a detailed description thereof will be omitted.

[0036] In the erection work, a shoring unit 3 is erected near the face K. The shoring unit 3 comprises a steel shoring 4, a connecting member 5, and a receiving member 6. In the erection work, a pair of left and right steel shoring 4, 4 are connected at the top to form an arch shape. When erecting the shoring unit 3, an installation process, an erection process, and a connection process are performed.

[0037] In the installation process, as shown in Fig. 5, a tie member 5 and a receiving member 6 are attached to a steel support 4 to form a support unit 3. The steel support 4 is formed by processing a so-called H-shaped steel consisting of a pair of flanges 41, 41 and a web 42 that spans the pair of flanges 41, 41. A bolt insertion hole 43 is formed in the web 42 corresponding to the attachment point of the tie member 5 (see Fig. 3).

[0038] As shown in FIG. 5(a), the receiving member 6 is laid horizontally on the face side end of the pair of flanges 41, 41 at a position corresponding to the connecting material 5. The receiving member 6 is a steel rod with both ends welded to the inner ends of the pair of flanges 41, 41. The configuration of the receiving member 6 is not limited. For example, when the flange spacing is large, as shown in FIG. 6(a), both ends can be bent and welded to the flanges to increase the degree of end fixation, so that a steel rod of a common diameter can be used. Also, as shown in FIGS. 6(a) and (b), by making the dimension from the web 42 to the receiving member 6 constant regardless of the size of the steel support 4, a common connecting material can be used.

[0039] The tie member 5 is a member that connects the steel supports 4 arranged at the front and rear, and is laid horizontally between the steel supports 4 arranged at the front and rear (see FIG. 1(b)). The tie member 5 is fixed with its tip (the end on the face K side) abutting against the web 42 of the steel support 4. The tie member 5 is fixed to the side surface of the web 42 at the tunnel mouth. As shown in FIGS. 5(a) and (b), the tie member 5 is made of a steel pipe, and a nut 51 is welded to the tip of the tie member 5 via a rotation stop member 53. The tie member 5 is fixed to the steel support 4 by fastening a bolt 52 that has passed through a bolt insertion hole 43 (see FIG. 6) of the web 42 to the nut 51.

[0040] As shown in Fig. 5(c), the rotation stop member 53 is made of a rectangular steel plate, and is welded to the tip of the tie material 5. The rotation stop member 53 is parallel to the web 42 of the steel support 4. A nut 51 is welded to the surface of the rotation stop member 53 opposite the tie material 5. The central axis of the nut 51 and the central axis of the tie material 5 are aligned. The rotation stop member 53 extends laterally from the tie material 5, and one side (tip) abuts against one flange 41 of the steel support 4 with the tie material 5 fixed to the steel support 4.

[0041] As shown in Figures 5(a) and (b), a mounting member 8 is provided at the base end (the end on the tunnel mouth side) of the connecting material 5. The mounting member 8 comprises a base 81 and a pair of guide members 82, 82. The base 81 is made of a rectangular steel plate, and is welded to the end face of the connecting material 5. The base 81 is parallel to the web 42 of the steel support 4.

[0042] The guide member 82 is made of a steel plate and is erected on the edge of the surface of the base 81 opposite to the connecting material 5. The guide member 82 is provided so as to be parallel to the flange 41 of the steel support 4. As shown in Fig. 5(d), the pair of guide members 82, 82 face each other across the center of the base 81 (arranged rotationally symmetrically).

[0043] The tip (first side 821) of the guide member 82 on the face side is parallel to the base 81. As shown in FIG. 5(e), the side (second side 822) extending from one end of the first side 821 extends in a direction away from the base 81 as it approaches the wellhead side. On the other hand, the side (sixth side 826) extending from the other end of the first side 821 is perpendicular to the first side 821. The third side 823 intersects with the wellhead side end of the second side 822 at an acute angle. The third side 823 extends in a direction approaching the other guide member 82 in side view as it approaches the face (base 81) side. The fourth side 824 intersects with the face (base 81) side end of the third side 823 at an obtuse angle. The fourth side 824 extends in a direction approaching the other guide member 82 in side view as it approaches the face (base 81) side. The inclination angle of the fourth side 824 with respect to the first side 821 is steeper than the inclination angle of the third side 823 with respect to the first side 821. The fifth side 825 intersects with the wellhead side end of the sixth side 826 at a right angle. The fifth side 825 is formed between the sixth side 826 and the fourth side 824. In this manner, the fifth side 825 and the sixth side 826 form a hook-shaped hook portion 83 in the guide member 82. The distance between the first side 821 and the fifth side 825 is equal to the diameter of the receiving member 6.

[0044] In addition, as shown in Figs. 7(a) and (b), a visual confirmation plate 54 is attached to the base end (the end on the wellhead side) of the connecting material 5 in this embodiment. The visual confirmation plate 54 is provided with an attachment portion 54a and a visual confirmation portion 54b by bending a metal plate into an L-shape. The attachment portion 54a is attached to the inner space side of the connecting material 5 and fixed to the connecting material 5 via a screw 54c. The attachment portion 54a has a T-shape with a width at the end greater than that of the other portions. In addition, the corners of the attachment portion 54a are bent so as to abut against the connecting material 5 side having a circular cross section. As shown in Fig. 7(b), the visual confirmation portion 54b protrudes laterally (toward the inner space) from the attachment portion 54a and is parallel to the web 42 of the steel support 4. In addition, the visual confirmation portion 54b has a length that protrudes toward the inner space side beyond the steel support 4 (flange 41). Furthermore, the surface of the visual confirmation portion 54b is colored in a color (for example, white) that is easy for the operator to confirm.

[0045] The ties 5 are attached to the steel support 4 by first placing the ties 5 on the face K side of the web 42 of the steel support 4 and inserting bolts 52 into the bolt insertion holes 43 formed in the web 42. The ties 5 are then attached to the steel support 4 by screwing the bolts 52 into the nuts 51 (see Figs. 5(a) and (b)).

[0046] In the erection process, the steel supports 4 to which the connecting members 5 are fixed are erected near the face K along the surface of the primary shotcrete 21 (or the ground surface Gs). At this time, the pair of left and right steel supports 4, 4 are assembled in an arch shape by connecting them at their tops (see FIG. 1(a)).

[0047] In the connection process, as shown in Fig. 8, the tie material 5 fixed to the steel support (new steel support) 4 is connected to the existing steel support 4a installed on the tunnel mouth side. The tie material 5 is connected to the existing steel support 4a by engaging the mounting member 8 with the receiving member 6 fixed to the existing steel support 4a.

[0048] In the connecting process, as shown in Figures 8(a) and (b), first, the steel support 4 is pulled toward the existing steel support 4a to bring the mounting member 8 close to the receiving member 6. At this time, the mounting member 8 is inserted into the space surrounded by the pair of flanges 41, 41 and the web 42 of the existing steel support 4a. When the steel support 4 is pulled, the receiving member 6 and the guide members 82, 82 of the mounting member 8 come into contact with each other, and the receiving member 6 slides along the third side 823 of one of the guide members 82, so that it is guided to the center of the guide members 82, 82, 82, as shown in Figures 9(a) and (c). Then, when the steel support 4 is further pulled toward the existing steel support 4a, as shown in Fig. 8(c), Fig. 9(b) and (d), the receiving member 6 slides on the fourth side 824, and the mounting member 8 rotates (the connecting material 5 twists) due to the guide gradient of the fourth side 824, and the guide members 82, 82 climb over the receiving member 6. When the guide members 82, 82 climb over the receiving member 6, as shown in Fig. 8(d) and Fig. 10(a)-(c), they enter the gap between the base 81 and the fifth side 825 of the receiving member, and the mounting member 8 rotates in the opposite direction to return to its original state. As a result, the receiving member 6 is caught by the hook portions 83 of the guide members 82, 82, and the base 81 abuts against the receiving member 6, and the mounting member 8 and the receiving member 6 are engaged with each other.

[0049] As shown in Fig. 10(c), a visual identification mark 45 is attached to the flange 41 of the existing steel support 4a at a position corresponding to the visual identification plate 54. The visual identification mark 45 is in a color (e.g., white) that is easy for an operator to see, and has, for example, a triangular shape. The visual identification mark 45 is attached to the flange 41 by drawing it on the flange 41 or by attaching a sticker on it.

[0050] The operator visually checks the visual identification mark 45 from the tunnel entrance side of the existing steel support 4a, and confirms that the mounting member 9 and the receiving member 6 are engaged based on the positional relationship between the tip of the visual identification mark 45 and the visual identification plate 54. In other words, when it is confirmed that the tip of the visual identification mark 45 overlaps with the visual identification plate 54, it is determined that the mounting member 9 and the receiving member 6 are engaged. The width dimension of the visual identification plate 54 is set to a size that allows it to be determined that they are engaged.

[0051] After the steel support 4 is connected to the existing steel support 4a by the connecting material 5, the secondary shotcrete 22 is sprayed toward the side of the tunnel T (see FIG. 1(b)).

[0052] According to the shoring unit 3 and shoring assembly method of this embodiment, the tie material 5 can be easily connected to the existing steel shoring 4a (existing shoring unit 3) simply by engaging the mounting member 8 with the receiving member 6. Therefore, even when the steel shoring 4 is assembled using heavy machinery, there is no need for workers to enter the exposed ground before the shoring is completed or directly below the primary shotcrete 21 in order to install the tie material 5.

[0053] Furthermore, the shoring unit 3 has a simple structure and is constructed by combining relatively easily available members (steel plates), so that the manufacturing costs can be kept low.

[0054] The embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and each of the above components can be appropriately modified without departing from the spirit of the present invention.

[0055] For example, in the first embodiment, the mounting member 7 is formed by processing one steel rod, but the mounting member 7 may be formed by combining a pair of steel rods 70, 70, as in the mounting member 7 shown in Fig. 11. The steel rod 70 constituting the mounting member 7 shown in Fig. 11 includes a base 76 fixed to the connecting material 5, a guide portion 77 inclined so as to approach the other steel rod 70 as it approaches the face side, and a connecting portion 78 connecting the base 76 and the guide portion 77. The shape of the steel rod 70 constituting the mounting member 7 is not limited.

[0056] In the above embodiment, the mounting member 7 is bolted to the connecting material 5, but as with the mounting member 7 (steel bar 70) shown in Fig. 11, the mounting member 7 may be welded to the end (outer surface, inner surface or end surface) of the connecting material 5, and the method of fixing the mounting member 7 is not limited. When welding the mounting member 7 to the connecting material 5, grooves or protrusions may be formed on the end of the connecting material 5 to prevent the mounting member 7 from slipping.

[0057] Furthermore, the material constituting the mounting member 7 is not limited, and for example, it may be formed by processing a plate material (spring plate). [Explanation of symbols]

[0058] 1 Shoring 2. Shotcrete 3 Shoring Unit 4 Steel shoring 41 Flange 42 Web 43 Bolt insertion hole 5. Connectors 51 Nut 52 Volts 6 Receiving member 7 Mounting material 71 Base 72 Horizontal section 73 Guide part 74 Fixing member (bolt) 75 Nut T-Tunnel

Claims

1. A steel support structure including a pair of flanges and a web horizontally extending across the pair of flanges; A tie material fixed to the wellhead side of the web; An attachment member provided at the wellhead side end of the connecting material; A support unit characterized in that it comprises a receiving member that can engage with the mounting member that is horizontally suspended from the face side ends of a pair of the flanges at a position corresponding to the connecting material.

2. The mounting member includes a base portion fixed to the end portion of the connecting material via a fixing member, a pair of horizontal portions extending from both ends of the base portion toward the tunnel mouth side, and a pair of guide portions extending from the tips of the pair of horizontal portions toward the tunnel face side, The pair of guide portions are inclined with respect to the horizontal portion so that their tips approach each other toward the face side, The support unit according to claim 1 , characterized in that the receiving member is a steel rod that can be inserted into a space surrounded by the base portion and the tips of the pair of guide portions.

3. The connecting material is made of a steel pipe with a nut fixed to the wellhead end, The support unit according to claim 2, characterized in that the fixing member is a bolt having the base welded to a head thereof and is screwed into the nut.

4. The mounting member includes a base portion made of a steel plate fixed to an end portion of the connecting material, and a pair of guide members extending from the base portion toward the entrance side, The support unit described in claim 1, characterized in that the pair of guide members face each other across the center of the base, and a hook portion capable of engaging with the receiving member is formed at the end on the base side.

5. An erection process of erecting the shoring unit according to any one of claims 1 to 4 in the vicinity of a face; A connecting process for connecting the shoring unit to another shoring unit provided on the tunnel mouth side via the connecting material, A support assembly method characterized in that, in the connecting process, the support unit is pulled toward the other support unit and the mounting member of the support unit is engaged with the receiving member of the other support unit.

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