A method for roof construction of a main tunnel by using an inclined shaft

Abstract

The application discloses a kind of inclined shaft into normal hole roof picking construction method, comprising the following steps: step S1, inclined shaft gentle slope section excavation support construction;First, erect several pieces of special-shaped arch frame in the intersection of temporary normal hole of inclined shaft special-shaped section, then erect at least two pieces of inclined shaft portal in the intersection transition section of inclined shaft and normal hole;Step S2, excavation support construction pilot hole;After forming operation platform by horizontal excavation by continuing along normal hole transversely roof picking of inclined shaft, continue to pick up and excavate slope obliquely upwards, and erect pilot hole portal during excavation;Step S3, construction pilot hole initial support;Continue to erect several pieces of ring steel arch frame as normal hole steel arch frame in pilot hole, and the end of ring steel arch frame close to pilot hole entrance is welded on the top end of inclined shaft portal;Step S4, excavation support construction normal hole;Normal hole is excavated along the two sides of pilot hole using three-step construction method, with the advantages of saving slag process time, supporting structure closed loop, supporting structure stable, easy and fast operation, etc.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology, specifically relating to a method for constructing a tunnel from an inclined shaft with the roof lifted. Background Technology

[0002] Common construction methods for entering the main tunnel via inclined shafts include straight-line climbing pilot tunnel, arc-shaped pilot tunnel, and small pilot tunnel turning and top-lifting construction. However, regardless of the construction method, they all involve large-scale disassembly and assembly of the initial support steel arch frame or pilot tunnel portal frame in the main tunnel, and do not take into account the problem of transporting excavated soil in the main tunnel, resulting in a long construction cycle and complicated procedures.

[0003] For example, in the case of the cantilever structure for the inclined shaft excavated into the main tunnel via the pilot tunnel, as per authorization announcement number CN215860227U, it is necessary to remove the temporary portal-shaped arch support columns, portal-shaped double-row steel frame columns, and portal-shaped single-row steel frame columns on the sidewall of the pilot tunnel after the initial support structure of the main tunnel in the "portal-shaped" pilot tunnel has reached the required strength. Moreover, the main tunnel steel arch frame and the portal-shaped frame of the pilot tunnel are assembled separately and are not enclosed into a closed loop, which will lead to the instability of the overall initial support structure.

[0004] For example, the method for replacing the support and lifting the top of the tunnel in the inclined shaft of the tunnel with application publication number CN112302687A requires that after each section of the initial support of the pilot tunnel is removed, the free face is excavated towards the top, and then the rectangular gantry of that section is raised to the top of the main tunnel, and the legs of the gantry are extended to the bottom of the rectangular pilot tunnel within the main tunnel range. It is necessary to repeatedly build and install the pilot tunnel support, which is time-consuming and labor-intensive. Summary of the Invention

[0005] This invention aims to provide a method for constructing the main tunnel from an inclined shaft, where the initial support of the steel frame is closed into a ring, resulting in strong stability of the initial support structure of the pilot tunnel and the main tunnel. This method solves the problems of instability of the overall initial support structure caused by the lack of a closed ring for the steel arch frame of the main tunnel, and the time-consuming and labor-intensive process of large-scale disassembly and assembly of the initial support steel arch frame of the main tunnel or the portal frame of the pilot tunnel.

[0006] Therefore, the technical solution adopted by this invention is: a method for constructing a jacking-up structure for an inclined shaft leading into the main tunnel, characterized by comprising the following steps:

[0007] Step S1: Excavation and support construction of the inclined shaft gentle slope section; First, erect several irregular arch frames at the intersection of the temporary main tunnel of the inclined shaft, and then erect at least two inclined shaft portal frames at the junction and transition section of the inclined shaft and the main tunnel, and ensure that the inclined shaft portal frames are tangent to the circumferential outline of the main tunnel.

[0008] Step S2: Excavate the pilot tunnel for support construction; after the pilot tunnel working platform is formed by horizontal excavation along the transverse top of the main tunnel through the inclined shaft, the top is continued to be excavated upwards to form a slope, and during the excavation process, pilot tunnel portal frames of different heights but equal widths are erected at equal intervals along the excavation direction; the working platform is level with the bottom of the middle step of the main tunnel excavation, and the highest point of the slope is level with the bottom of the upper step of the main tunnel excavation;

[0009] Step S3: Construct initial support for the pilot tunnel; continue to construct several longitudinally equidistant ring steel arch frames as main tunnel steel arch frames within the pilot tunnel. The ring steel arch frames are installed close to the top of the pilot tunnel portal frame. The end of the ring steel arch frame near the entrance of the pilot tunnel is welded to the top of the inclined shaft portal frame, and all the support legs of the pilot tunnel portal frame are cut off.

[0010] Step S4: Excavation and support construction of the main tunnel; The main tunnel is excavated longitudinally along both sides of the pilot tunnel using the three-stage construction method.

[0011] As a preferred embodiment of the above scheme, in step S1, 11 irregular arch frames and 2 inclined shaft gantry frames are used, and the height of the inclined shaft gantry frames is 4.5m to 5m and the width is 3.5m to 4m, to ensure the normal passage of equipment such as tank trucks and loaders, and to avoid the situation where the equipment cannot pass due to insufficient space, thus preventing the excavation, slag transportation and other processes from being carried out.

[0012] More preferably, in step S1, the irregular arch frame is provided with a locking anchor pipe at the arch foot. The locking anchor pipe has a diameter φ of 42mm, a length L of 2.5m, and is arranged at a downward angle of 20°, which effectively increases the stability of the inclined shaft support.

[0013] Further preferably, in step S2, the length of the working platform is 3m to 3.5m, and the width is 3.5m to 4m. The size is appropriate, which facilitates the operation and turning of the equipment and provides a platform for subsequent construction operations for the construction personnel. The design is reasonable. The slope is 15° to 30°, which is appropriate and makes it easy to remove slag during excavation. Compared with a flat surface, the slope has less resistance to slag removal and can effectively save the construction period. The width of all guide tunnel gantry frames is consistent with the width of the working platform to ensure maximum utilization of space.

[0014] More preferably, in step S2, the guide tunnel gantry is made of I18 steel frame, and 14 guide tunnel gantry frames with a spacing of 1m to 1.2m are provided along the guide tunnel to ensure the stability of the support structure of the guide tunnel and to protect the life safety of construction personnel.

[0015] More preferably, in step S2, anchor mesh spraying is used to reinforce the portal frame of the guide tunnel, which has a good support effect.

[0016] More preferably, in step S3, the ring steel arch frame is made of I18 I-beams, the arch part is made of φ22 combined hollow anchor rods, and the sidewalls are made of φ22 mortar anchor rods to fix the ring steel arch frame to the surrounding rock. The design is reasonable and ensures the stability of the main tunnel.

[0017] More preferably, in step S3, the weld between the ring steel arch frame and the inclined shaft portal frame is fixed with a locking foot anchor pipe to ensure high stability of the support structure.

[0018] The beneficial effects of this invention are:

[0019] (1) The working platform inside the pilot tunnel can provide a parking area for equipment such as tank trucks, muck trucks, and loaders, ensuring the smooth progress of tunneling and muck transportation processes, facilitating construction work. The slope inside the pilot tunnel is more convenient for muck transportation and removal, and the slope will cause some muck to roll off, saving time in the muck removal process.

[0020] (2) During the excavation of the pilot tunnel, the pilot tunnel portal frames of varying heights but equal widths are erected at equal intervals along the excavation direction according to the excavation advance. This allows for rapid closure into a ring, ensuring the safety of the pilot tunnel excavation. After the pilot tunnel excavation is completed, the pilot tunnel portal frames are retained, and the ring steel arch frame of the main tunnel is installed inside the pilot tunnel portal frames. This ensures safe construction, convenient and quick operation, and provides double temporary support. The end of the ring steel arch frame of the main tunnel near the entrance of the pilot tunnel is welded to the top of the inclined shaft portal frame, forming a closed ring support structure, which effectively ensures the stability of the overall support structure.

[0021] (3) At least two inclined shaft portal frames shall be erected at the junction of the inclined shaft and the main tunnel to ensure that there is enough welding space when the ring steel arch frame is welded at the top. The inclined shaft portal frame shall be tangent to the circumferential outline of the main tunnel to avoid encroachment and insufficient clearance of the lining at the junction of the inclined shaft and the main tunnel, thus effectively avoiding the occurrence of lateral reaction deformation.

[0022] (4) The top excavation does not require the back-and-forth installation of the guide tunnel gantry legs, which effectively shortens the construction cycle, saves construction time and reduces labor costs. When longitudinal excavation begins along both sides of the guide tunnel, only the guide tunnel gantry legs need to be cut off once, making the operation convenient and quick.

[0023] In summary, it has advantages such as saving slag removal time, rapid closure of the support structure into a ring, stable support structure, and convenient and quick operation. Attached Figure Description

[0024] Figure 1 This is a top view of the inclined shaft.

[0025] Figure 2 This is a schematic diagram of the guide tunnel structure.

[0026] Figure 3 This is a schematic diagram of the portal frame structure erected during the excavation of the pilot tunnel.

[0027] Figure 4 This is a schematic diagram of the structure where the ring steel arch frame is welded to the inclined shaft portal frame. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments and accompanying drawings:

[0029] Combination Figure 1 — Figure 4 As shown, a method for constructing a jacking tunnel from an inclined shaft to the main tunnel is described, with the following specific implementation steps:

[0030] Step S1: Excavation and support construction of the gentle slope section of inclined shaft 1; First, erect several irregular arch frames 2 at the intersection of the temporary main tunnel 3 of inclined shaft 1, and then erect at least two inclined shaft portal frames 21 at the junction and transition section of inclined shaft 1 and main tunnel 3, and ensure that the inclined shaft portal frame 21 is tangent to the circumferential outline of main tunnel 3.

[0031] In step S1, 11 irregular arch frames 2 are used, and 2 inclined shaft portal frames 21 are used. The height of the inclined shaft portal frame 21 is preferably 4.5m to 5m, and the width is preferably 3.5m to 4m.

[0032] The irregular arch frame 2 is equipped with locking anchor pipes at the arch foot. The diameter of the locking anchor pipe is φ42mm and the length is L2.5m. Two locking anchor pipes are set at each arch foot position and arranged at a 20° angle downward from the horizontal line. The arch wall uses φ22 mortar anchor rods with L=3m, with a circumferential longitudinal spacing of 1.2m×1.2m and a quincunx arrangement.

[0033] Then, φ6 steel mesh with a mesh spacing of 25×25cm is welded to the top surface of the irregular arch frame 2 and the inclined shaft portal frame 21, and finally, 22cm thick C25 concrete is sprayed on.

[0034] Step S2: Excavation and support of the pilot tunnel 4; After the pilot tunnel 4 is formed by horizontal excavation along the main tunnel 3 through the inclined shaft 1, the pilot tunnel 4 is formed by horizontal excavation. The pilot tunnel 4 is then formed by upward excavation. During the excavation, pilot tunnel gantry frames 5 of different heights but equal widths are erected at equal intervals along the excavation direction for initial support. The working platform 41 is level with the bottom of the middle step of the main tunnel 3, and the highest point of the slope 42 is level with the bottom of the upper step of the main tunnel 3.

[0035] In step S2, anchor mesh spraying support is used to reinforce the portal frame 5 of the guide tunnel.

[0036] In step S2, the length of the working platform 41 is preferably 3m to 3.5m, the width is preferably 3.5m to 4m, the slope of the ramp 42 is preferably 15° to 30°, and the width of all guide tunnel gantry frames is consistent with the width of the working platform.

[0037] In step S2, the guide tunnel gantry 5 is made of I18 steel frame, and 14 guide tunnel gantry 5 with a spacing of 1m to 1.2m are provided along the guide tunnel 4.

[0038] Step S3: Construct initial support for the pilot tunnel 4; continue to construct several longitudinally equidistant ring steel arch frames 6 as main tunnel steel arch frames within the pilot tunnel 4. The ring steel arch frames 6 are installed close to the top of the pilot tunnel portal frame 5. The end of the ring steel arch frame 6 near the entrance of the pilot tunnel 4 is welded to the top of the inclined shaft portal frame 21, and all the legs of the pilot tunnel portal frames are cut off and removed.

[0039] In step S3, the ring steel arch frame 6 uses I18 I-beams, and the arch part uses φ22 combined hollow anchor rods. The length L of the hollow anchor rods is 3.5m, and the longitudinal spacing of the ring is 1.2m×1.2m.

[0040] The sidewall is fixed to the surrounding rock with φ22 mortar anchor rods. The length L of the mortar anchor rod is 3.5m and the longitudinal spacing of the ring is 1.2m×1.2m.

[0041] It also lays and welds a φ6 steel mesh with 20*20cm diameter, and φ42 advanced small guide tubes with 40 tubes per ring and a length of 4.5m.

[0042] In step S3, the steel ring arch 6 and the inclined shaft portal frame 21 are fixed with a locking foot anchor pipe at the welding point. The locking foot anchor pipe has a diameter of φ42 and a length L of 3m.

[0043] Step S4: Excavation and support construction of the main tunnel 3; The main tunnel 3 is excavated longitudinally along both sides of the pilot tunnel 4 using the three-stage construction method.

[0044] First, excavation and support construction are carried out on the upper and middle steps of the main tunnel to form the upper and middle steps. Then, the upper, middle and lower steps of the main tunnel are excavated to form a three-stage construction.

Claims

1. A method for constructing a jacking-off section in an inclined shaft leading to a main tunnel, characterized in that, Includes the following steps: Step S1: Excavation and support construction of the gentle slope section of the inclined shaft (1); First, erect several irregular arch frames (2) at the irregular section of the intersection of the inclined shaft (1) and the main tunnel (3), and then erect at least two inclined shaft portal frames (21) at the junction transition section of the inclined shaft (1) and the main tunnel (3), and ensure that the inclined shaft portal frame (21) is tangent to the circumferential outline of the main tunnel (3); In step S1, 11 irregular arch frames (2) are used, and 2 inclined shaft portal frames (21) are used. The height of the inclined shaft portal frames (21) is 4.5m to 5m and the width is 3.5m to 4m. In step S1, the irregular arch frame (2) is provided with a locking foot anchor pipe at the arch foot. The diameter φ of the locking foot anchor pipe is 42mm, the length L is 2.5m, and it is arranged at a downward angle of 20°. Step S2: Excavate the support construction guide tunnel (4); after the working platform (41) of the guide tunnel (4) is formed by horizontal excavation along the main tunnel (3) through the inclined shaft (1), the top is continued to be excavated upward to form a slope (42), and guide tunnel portal frames (5) of different heights but equal widths are erected at equal intervals along the excavation direction during the excavation process; the working platform (41) is flush with the bottom of the middle step of the main tunnel (3), and the highest point of the slope (42) is flush with the bottom of the upper step of the main tunnel (3); Step S3: Construct initial support for the pilot tunnel (4); continue to construct several longitudinally equidistant ring steel arch frames (6) in the pilot tunnel (4) as steel arch frames for the main tunnel (3). The ring steel arch frames (6) are installed close to the top of the pilot tunnel portal frame (5). The end of the ring steel arch frame (6) near the entrance of the pilot tunnel (4) is welded to the top of the inclined shaft portal frame (21), and all the legs of the pilot tunnel portal frame (5) are cut off. In step S3, the weld between the ring steel arch frame (6) and the inclined shaft gate frame (21) is fixed with a locking foot anchor pipe; Step S4: Excavation and support construction of the main tunnel (3); The main tunnel (3) is excavated longitudinally along both sides of the pilot tunnel (4) using the three-stage construction method.

2. The method for constructing a jacking-up structure for an inclined shaft leading into the main tunnel according to claim 1, characterized in that: In step S2, the length of the working platform (41) is 3m to 3.5m and the width is 3.5m to 4m. The slope of the ramp (42) is 15° to 30°. The width of all the guide tunnel gantry (5) is the same as the width of the working platform (41).

3. The method for constructing a jacking-up structure for an inclined shaft leading into the main tunnel according to claim 1, characterized in that: In step S2, the guide tunnel gantry (5) is made of I18 steel frame, and 14 guide tunnel gantry (5) with a spacing of 1m to 1.2m are provided along the guide tunnel (4).

4. The method for constructing a jacking-up structure for an inclined shaft leading into the main tunnel according to claim 1, characterized in that: In step S2, anchor mesh spraying support is used to reinforce the portal frame of the guide tunnel (5).

5. The method for constructing a jacking-up structure for an inclined shaft leading into the main tunnel according to claim 1, characterized in that: In step S3, the ring steel arch frame (6) is made of I18 I-beams, the arch is made of φ22 combined hollow anchor rods, and the sidewall is made of φ22 mortar anchor rods to fix the ring steel arch frame (6) to the surrounding rock.

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