Initial support construction method for segmented excavation of large-span tunnels

Abstract

The invention relates to an initial support construction method for segmented excavation of a large-span tunnel. During segmented excavation, a temporary support is used to install and fix an arc-shaped supply sheet. The temporary support device comprises a screw sleeve and two symmetrically arranged connection units. The connection units comprise end plates and screws connected in sequence. The screws of the two connection units rotate in opposite directions or the internal threads at two ends of the screw sleeve rotate in opposite directions. The outer end of the screw is hinged to the end plate via an adjusting bolt, and the inner end of the bolt extends into the screw sleeve and is threadedly matched therewith. The method has high safety and strong operability, shortens the initial support construction period, reduces the investment cost of engineering materials, is easy to disassemble and assemble, does not occupy the working space below, is convenient for the construction of the next process, reduces the risk of structural damage caused by blasting and mechanical operations, and is suitable for temporary support for excavation of a large-span tunnel with relatively stable surrounding rock.

Description

Technical Field

[0001] The invention relates to an initial support construction method for segmented excavation of a large-span tunnel. Background Art

[0002] During tunnel excavation, support is required. In the process of tunnel excavation, the initial support is mostly based on steel arches. The arches include several arch units at intervals along the tunnel excavation direction. Each arch is connected by connecting steel bars. Each arch unit is composed of several arc-shaped arch pieces connected in sequence. For tunnels that are excavated in sections and steps by drilling and blasting, it is necessary to set up arc-shaped arch pieces at intervals along the tunnel excavation direction at the top of the first excavated area. The arc-shaped arch pieces are initially fixed with grouting anchors. In order to prevent the displacement of the arc-shaped arch pieces during anchor grouting and the displacement or even falling of the arc-shaped arch pieces under the influence of external forces during subsequent processing, it is necessary to temporarily support each arc-shaped arch piece through I-beam columns. This support method requires the use of a large number of I-beams, which is costly, time-consuming and labor-intensive to set up, and has a long construction period. It also occupies the working space and is not convenient for the next process. During blasting and mechanical construction, it is easy to cause structural damage to the columns, thereby losing the supporting function, greatly reducing the safety of the next stage of construction. Summary of the invention

[0003] The purpose of the present invention is to address the above shortcomings and provide an initial support construction method for segmented excavation of a large-span tunnel.

[0004] The solution adopted by the present invention to solve the technical problem is an initial support construction method for segmented excavation of a large-span tunnel, comprising the following steps:

[0005] Step 1: Divide the tunnel into N excavation areas along the tunnel width according to the actual working conditions, where N is not less than 2;

[0006] Step 2: excavate the first excavation area along the tunneling direction according to the excavation progress;

[0007] Step 3: Arrange and install arc-shaped arch pieces along the tunneling direction at the top of the first excavation area, install temporary support devices at the ends of the arc-shaped arch pieces, and connect the temporary support devices to the side walls of the rock layer to be excavated. Adjacent arc-shaped arch pieces are connected by connecting steel bars. Subsequently, the arc-shaped arch pieces are connected to the top of the excavation area by anchor rods, and then the anchor rods are sprayed with anchors at the initial stage.

[0008] Step 4: After the initial spraying and anchoring is completed and the sprayed concrete solidifies, prepare to excavate the next excavation area on the side adjacent to the first excavation area along the tunnel excavation direction. Remove the temporary support device at the excavation site according to the excavation progress;

[0009] Step 5: An arc-shaped arch piece is erected on the top of the newly excavated area, one end of which is connected to the end of the corresponding arc-shaped arch piece installed in the adjacent excavation area, and the other end is connected to the side wall of the rock layer to be excavated or the ground through a temporary support device; then, the arc-shaped arch piece is connected to the cave top through an anchor rod, and then the anchor rod is subjected to initial spraying operation;

[0010] Step 6: After the initial spraying and anchoring is completed and the sprayed concrete solidifies, prepare to excavate the next excavation area on the other side of the first excavation area or another excavation area adjacent to the excavation area that has not been excavated yet; according to the excavation progress, remove the temporary support device at the excavation site;

[0011] Step 7: Repeat steps 5 and 6 until all N excavation areas are excavated. The corresponding arc-shaped arch pieces in the N excavation areas are connected to form a ring of arch frame units, thereby achieving initial support for the excavation area at this location.

[0012] In step 2, if the first section of excavation is the end of a tunnel, the upper end of the arc-shaped arch piece is connected to the side wall of the rock formation to be excavated through a temporary support device, and the lower end is connected and fixed to the ground; if the first section of excavation is not the end of a tunnel, the two ends of the arc-shaped arch piece are respectively connected to the side walls of the rock formation to be excavated on both sides through temporary support devices;

[0013] Furthermore, the temporary support device includes a screw sleeve and two symmetrically arranged connecting units, the connecting units include end plates and screws connected in sequence, the screws of the two connecting units have opposite rotation directions or the internal threads at both ends of the screw sleeve have opposite rotation directions, the outer end of the screw is hinged to the end plate through an adjusting bolt, and the inner end of the screw extends into the screw sleeve and threadedly cooperates with it.

[0014] Furthermore, a wrench socket is provided in the middle of the screw sleeve.

[0015] Furthermore, a plurality of connection holes are provided on the peripheral side of the end plate to connect and fix with the side wall of the rock formation or the end of the arc-shaped arch piece.

[0016] Furthermore, a rubber layer is provided on the outer side of the end plate, and the connecting hole passes through the rubber layer.

[0017] Furthermore, the adjusting bolt locks the end plate and the screw rod through a nut.

[0018] Furthermore, the screw sleeve outer cover is provided with a protective sleeve, the protective sleeve is coaxial with the screw, and the two ends of the protective sleeve are respectively connected to the peripheral sides of the outer ends of the screw on both sides.

[0019] Furthermore, the protective sleeve includes two sleeve units, which are respectively sleeved on the outside of two screws. The inner diameter of the sleeve unit is larger than the outer diameter of the screw sleeve. An end plate is provided at the outer end of the sleeve unit. A mounting hole for connecting the screw is provided in the middle of the end plate. An annular groove is provided on the peripheral side of the outer end of the screw, and the side wall of the mounting hole is inserted into the sliding groove.

[0020] Furthermore, the two sleeve units have the same size, and the length of the sleeve unit is no greater than half the length of the threaded sleeve.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the use of temporary supports to install and fix the arc-shaped arch pieces is highly safe and highly operable, shortens the initial support construction period, reduces the investment cost of engineering materials, is easy to disassemble and assemble, does not occupy the working space below, is convenient for the next construction process, reduces the risk of structural damage caused by blasting and mechanical operations, and is suitable for temporary support for large-span tunnel excavation with relatively stable surrounding rock. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described below in conjunction with the accompanying drawings.

[0023] Figure 1 It is a schematic diagram of the implementation structure of the temporary support device.

[0024] Figure 2 It is a schematic diagram of the tunnel excavation face in which the temporary support device is used to set up the arch frame.

[0025] Figure 3 This is a top view in the tunneling direction of a tunnel in which the temporary support device is used to set up an arch frame.

[0026] In the figure: 1-temporary support device; 101-threaded sleeve; 102-screw rod; 103-end plate; 104-adjusting bolt; 105-wrench socket; 106-protective sleeve; 2-arc arch piece; 3-anchor rod; 4-rock layer side wall; 5-first excavation area; 6-second excavation area; 7-third excavation area; 8-arch frame unit; 9-connecting steel bars; 10-unexcavated area. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] like Figure 1-3 As shown, an initial support construction method for segmented excavation of a large-span tunnel comprises the following steps:

[0029] Step 1: Divide the tunnel into N excavation areas along the tunnel width according to the actual working conditions, where N is not less than 2;

[0030] Step 2: excavate the first excavation area along the tunneling direction according to the excavation progress;

[0031] Step 3: Arrange and install arc-shaped arch pieces 2 along the tunneling direction at the top of the first excavation area, install temporary support devices 1 at the ends of the arc-shaped arch pieces, and connect the temporary support devices to the side walls 4 of the rock formation to be excavated, and connect adjacent arc-shaped arch pieces through connecting steel bars 9. Subsequently, the arc-shaped arch pieces are connected to the top of the excavation area through anchor rods 3, and then the anchor rods are subjected to initial spraying operations;

[0032] Step 4: After the initial spraying and anchoring is completed and the sprayed concrete solidifies, prepare to excavate the next excavation area on the side adjacent to the first excavation area along the tunnel excavation direction. Remove the temporary support device at the excavation site according to the excavation progress;

[0033] Step 5: An arc-shaped arch piece is erected on the top of the newly excavated area, one end of which is connected to the end of the corresponding arc-shaped arch piece installed in the adjacent excavation area, and the other end is connected to the side wall of the rock layer to be excavated or the ground through a temporary support device; then, the arc-shaped arch piece is connected to the cave top through an anchor rod, and then the anchor rod is subjected to initial spraying operation;

[0034] Step 6: After the initial spraying and anchoring is completed and the sprayed concrete solidifies, prepare to excavate the next excavation area on the other side of the first excavation area or another excavation area adjacent to the excavation area that has not been excavated yet; according to the excavation progress, remove the temporary support device at the excavation site;

[0035] Step 7: Repeat steps 5 and 6 until all N excavation areas are excavated. The corresponding arc-shaped arch pieces in the N excavation areas are connected to form a ring of arch frame units 8, thereby achieving initial support for the excavation area at this location.

[0036] In step 2, if the first section of excavation is the end of a tunnel, the upper end of the arc-shaped arch piece is connected to the side wall of the rock formation to be excavated through a temporary support device, and the lower end is connected and fixed to the ground; if the first section of excavation is not the end of a tunnel, the two ends of the arc-shaped arch piece are respectively connected to the side walls of the rock formation to be excavated on both sides through temporary support devices;

[0037] In this embodiment, the temporary support device includes a screw sleeve 101 and two symmetrically arranged connecting units. The connecting units include an end plate 103 and a screw 102 connected in sequence. The screw rotation directions of the two connecting units are opposite or the internal threads at the two ends of the screw sleeve have opposite rotation directions. The outer end of the screw is hinged to the end plate through an adjusting bolt 104, and the inner end of the screw extends into the screw sleeve and threadedly cooperates with it. The outer cover of the screw sleeve is provided with a protective sleeve 106, which is used to protect the temporary support device during blasting to prevent the temporary support device from being damaged by blasting, thereby reducing the damage rate of the support device and improving the reuse rate of the support device. A plurality of connecting holes are opened on the peripheral side of the end plate to connect and fix it to the side wall 4 of the rock formation or the end of the arc-shaped arch piece 2.

[0038] In this embodiment, a wrench insertion hole 105 is provided in the middle of the screw sleeve, and a hole portion for making way for the wrench insertion hole is provided on the protective sleeve.

[0039] In this embodiment, a rubber layer is provided on the outer side of the end plate, and the connecting hole passes through the rubber layer.

[0040] In this embodiment, the adjusting bolt locks the end plate and the screw rod through a nut.

[0041] In this embodiment, the screw sleeve outer cover is provided with a protective sleeve, the protective sleeve is coaxial with the screw, and the two ends of the protective sleeve are respectively connected to the peripheral sides of the outer ends of the screw on both sides.

[0042] In this embodiment, the protective sleeve includes two sleeve units, which are respectively sleeved on the outside of two screws. The inner diameter of the sleeve unit is larger than the outer diameter of the screw sleeve. An end plate is provided at the outer end of the sleeve unit. A mounting hole for connecting the screw is provided in the middle of the end plate. An annular groove is provided on the peripheral side of the outer end of the screw, and the side wall of the mounting hole is inserted into the sliding groove.

[0043] In this embodiment, the two sleeve units have the same size, and the length of the sleeve unit is no greater than half the length of the threaded sleeve.

[0044] In this embodiment, the protective sleeve is made of a flexible material, such as rubber, and is used to protect the screw and the screw sleeve covering it to prevent flying rocks generated by blasting operations from damaging the screw and the screw sleeve; at the same time, cement and dust generated during the spraying and anchoring operation will also be blocked by the protective sleeve.

[0045] Take the step-by-step excavation of three zones along the width direction of the tunnel as an example: in the first excavation zone 5, one end of the temporary support device is connected to the end of the arc-shaped arch piece by bolts, and then the other end of the temporary support device is connected to the side wall of the rock formation to be opened, so as to fix the arc-shaped arch piece, and then the arc-shaped arch piece is connected to the cave top by the anchor rod 3, and then the anchor rod is subjected to initial spraying and anchoring operation, so as to complete the construction of the arc-shaped arch piece in this area; after the initial spraying and anchoring is completed, the sprayed concrete solidifies, and the second excavation zone 6 adjacent to the first excavation zone is excavated, and the temporary support device at the excavation site is removed according to the excavation progress; then an arc-shaped arch piece is erected on the top of the new excavation area, one end of the arc-shaped arch piece is connected to the end of the arc-shaped arch piece corresponding to the first excavation zone, and the other end is connected to the side wall of the rock formation to be opened through the temporary support device, and then, The arc-shaped arch piece is connected to the top of the tunnel by anchor rods, and then the anchor rods are initially sprayed with anchors to complete the construction of the arc-shaped arch piece in this area; after the initial spraying and anchoring is completed, the sprayed concrete solidifies, and the third excavation area 7 adjacent to the second excavation area is excavated, and the temporary support device at the excavation site is removed according to the excavation progress; then an arc-shaped arch piece is erected on the top of the newly excavated area, one end of the arc-shaped arch piece is connected to the end of the arc-shaped arch piece corresponding to the second excavation area, and the other end is connected and fixed to the bottom surface of the tunnel, and then the arc-shaped arch piece is connected to the top of the tunnel by anchor rods, and then the anchor rods are initially sprayed with anchors to complete the construction of an arch frame unit into a ring; then, the first excavation area is excavated again, and then the arc-shaped arch piece of the newly excavated part is erected, and this cycle is repeated to form an initial support for the excavation area.

[0046] If this patent discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connected by bolts or screws), or as: a non-detachable fixed connection (for example, riveting, welding). Of course, the fixed connection can also be replaced by an integrated structure (for example, manufactured by a casting process) (except when it is obviously impossible to use an integrated forming process).

[0047] In the description of this patent, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this patent, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this patent.

[0048] The preferred embodiments listed above further illustrate the objectives, technical solutions and advantages of the present invention in detail. It should be understood that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An initial support construction method for segmented excavation of a large-span tunnel, characterized in that: The following steps are involved: Step 1: According to the actual working conditions, N excavation areas are divided along the width of the tunnel, and N is not less than 2; Step 2: excavate the first excavation area along the tunneling direction according to the excavation progress; Step 3: Arrange and install arc-shaped arch pieces along the tunneling direction at the top of the first excavation area, install temporary support devices at the ends of the arc-shaped arch pieces, and connect the temporary support devices to the side walls of the rock layer to be excavated. Adjacent arc-shaped arch pieces are connected by connecting steel bars. Subsequently, the arc-shaped arch pieces are connected to the top of the excavation area by anchor rods, and then the anchor rods are sprayed with anchors at the initial stage. Step 4: After the initial spraying and anchoring is completed and the sprayed concrete solidifies, prepare to excavate the next excavation area on the side adjacent to the first excavation area along the tunnel excavation direction. Remove the temporary support device at the excavation site according to the excavation progress; Step 5: An arc-shaped arch piece is erected on the top of the newly excavated area, one end of which is connected to the end of the corresponding arc-shaped arch piece installed in the adjacent excavation area, and the other end is connected to the side wall of the rock layer to be excavated or the ground through a temporary support device; then, the arc-shaped arch piece is connected to the cave top through an anchor rod, and then the anchor rod is subjected to initial spraying operation; Step 6: After the initial spraying and anchoring is completed and the sprayed concrete solidifies, prepare to excavate the next excavation area on the other side of the first excavation area or another excavation area adjacent to the excavation area that has not been excavated yet; according to the excavation progress, remove the temporary support device at the excavation site; Step 7: Repeat steps 5 and 6 until the excavation of N excavation areas is completed, and the corresponding arc-shaped arch pieces in the N excavation areas are connected to form a ring of arch frame units, thereby realizing the initial support of the excavation area at this position; In step 2, if the first section of excavation is the end of a tunnel, the upper end of the arc-shaped arch piece is connected to the side wall of the rock layer to be excavated via a temporary support device, and the lower end is connected and fixed to the ground; if the first section of excavation is not the end of a tunnel, the two ends of the arc-shaped arch piece are respectively connected to the side walls of the rock layer to be excavated on both sides through temporary support devices.

2. The initial support construction method for staged excavation of a large-span tunnel according to claim 1 is characterized in that: The temporary support device includes a screw sleeve and two symmetrically arranged connection units. The connection units include end plates and screws connected in sequence. The screws of the two connection units have opposite rotation directions or the internal threads at the two ends of the screw sleeve have opposite rotation directions. The outer end of the screw is hinged to the end plate via an adjusting bolt, and the inner end of the screw extends into the screw sleeve and is threadedly matched therewith.

3. The initial support construction method for staged excavation of a large-span tunnel according to claim 2 is characterized in that: A wrench insertion hole is arranged in the middle of the screw sleeve.

4. The initial support construction method for staged excavation of a large-span tunnel according to claim 2 is characterized in that: A plurality of connection holes are provided on the peripheral side of the end plate so as to be connected and fixed with the side wall of the rock formation or the end of the arc-shaped arch piece.

5. The initial support construction method for staged excavation of a large-span tunnel according to claim 2 is characterized in that: The adjusting bolt locks the end plate and the screw rod through a nut.

6. The initial support construction method for staged excavation of a large-span tunnel according to claim 2 is characterized in that: The outer cover of the screw sleeve is provided with a protective sleeve, the protective sleeve is coaxial with the screw rod, and the two ends of the protective sleeve are respectively connected to the peripheral sides of the outer ends of the screw rod on both sides.

7. The initial support construction method for staged excavation of a large-span tunnel according to claim 6 is characterized by: The protective sleeve includes two sleeve units, which are respectively sleeved outside the two screws. The inner diameter of the sleeve unit is larger than the outer diameter of the screw sleeve. An end plate is provided at the outer end of the sleeve unit. A mounting hole for connecting the screw is provided in the middle of the end plate. An annular groove is provided on the peripheral side of the outer end of the screw, and the side wall of the mounting hole is inserted into the sliding groove.

8. The initial support construction method for staged excavation of a large-span tunnel according to claim 7 is characterized in that: The two sleeve units have the same size, and the length of the sleeve unit is no greater than half of the length of the screw sleeve.

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