阅读说明：本技术 一种隧道交叉口小导洞施工方法 (Tunnel intersection small pilot tunnel construction method ) 是由 杨辉 熊成宇 宋宝顺 雷唐林 李金胜 于 2020-03-31 设计创作，主要内容包括：本发明公开了详细介绍了一种隧道交叉口小导洞施工方法,包括以下步骤：步骤一、根据新增斜井与正洞的相交角度为60°,新增斜井底端加强段衬砌钢架为I14钢架,纵向间距1.2m,属Ⅲ级围岩；隧道斜井托梁门架配合锁脚锚杆、超前小导管加强支护正洞型钢拱架进正洞的施工技术,为同类大断面隧道斜井小导洞进洞施工提供参考依据；缓解主洞施工工期压力的同时,提高隧道瓦斯段施工安全性；详细介绍了桐梓隧道4#斜井与正洞交叉段采用双拼门架、增加锁脚,加强超前支护,加强监控量测等手段,安全高质完成了斜井交叉口施工,实现辅助正洞施工的要求,可为今后特长大跨隧道斜井交叉口的施工提供参考。(The invention discloses a construction method for a small pilot tunnel at a tunnel intersection, which comprises the following steps: step one, according to the fact that the intersection angle of the newly-added inclined shaft and the main tunnel is 60 degrees, lining steel frames of the reinforcing section at the bottom end of the newly-added inclined shaft are I14 steel frames, the longitudinal distance is 1.2m, and the lining steel frames belong to class III surrounding rock; the construction technology of the tunnel inclined shaft joist portal frame matched with the foot locking anchor rod and the advanced small guide pipe to strengthen the support of the main tunnel type steel arch frame into the main tunnel provides reference basis for the construction of the inclined shaft small guide hole into the tunnel of the similar large-section tunnel; the construction safety of the gas section of the tunnel is improved while the pressure of the construction period of the main tunnel is relieved; the method introduces the means of double-spliced portal frames, increased locking feet, advanced support enhancement, monitoring measurement enhancement and the like at the cross section of the 4# inclined shaft and the main tunnel of the tung catalpa tunnel in detail, completes the construction of the inclined shaft intersection with high safety and high quality, meets the requirement of assisting the main tunnel construction, and can provide reference for the construction of the inclined shaft intersection of the extra-long-span tunnel in the future.)

1. A tunnel intersection small pilot tunnel construction method is characterized by comprising the following steps:

step one, according to the fact that the intersection angle of the newly-added inclined shaft and the main tunnel is 60 degrees, lining steel frames of the reinforcing section at the bottom end of the newly-added inclined shaft are I14 steel frames, the longitudinal distance is 1.2m, and the lining steel frames belong to class III surrounding rock; the excavation width of the reinforcement section of the newly added inclined shaft is 11.16m, and the width of the intersection section of the inclined shaft and the main tunnel is 12.89 m; the steel frame spacing of the steel frame is required to be adjusted in the steering of the steel frame at the bottom end of the inclined shaft, the steel frame spacing at the right side of the inclined shaft hole is set according to 1.2 m/pin, the steel frame spacing at the left side of the inclined shaft hole is set according to 1.8 m/pin, and the steel frame of the inclined shaft is gradually steered from the direction perpendicular to the central line of the inclined shaft to the direction parallel to the central line of the main hole through the adjustment of 10 steel frames;

and step two, the portal is used as a stress supporting platform of the main tunnel steel frame. The door frame is formed by combining, welding and processing double-spliced I22b steel frames. When the inclined shaft is constructed to the 10 th arch frame at the bottom end, firstly digging and installing a double-spliced I22 type steel arch frame, after the arch frame is installed, constructing the 10 th arch frame at the bottom end of the inclined shaft, and firmly welding the arch frame with the double-spliced arch frame, respectively arranging a pair of locking anchor rods at the middle part of the arch frame for welding and fixing, and welding the top parts of the inclined shaft arch frame and the double-spliced type steel arch frame by adopting I22 type steel;

and step three, adopting an I14 steel frame as the steering primary support of the inclined shaft section, and performing tunneling steering on the inclined shaft full section. The outer side length of the turning section is 19m, the inner side length of the turning section is 7m, the turning is finished according to 10 steel frames, the distance between the outer side steel frames is 10 multiplied by 1.9m, the distance between the inner side steel frames is 10 multiplied by 0.7m, and the arch crown elevation is gradually raised in the turning stage to be consistent with the height of the top of the main tunnel;

fourthly, bell mouth expanding excavation is finished by 6I 14 steel primary support steel frames, the bell mouth expanding excavation length is 5m, 6 steel frames are totally used, the distance is 1.0m, the 6 th steel frame is expanded to the normal section of the upper step of the main tunnel, the expanding excavation section adopts weak blasting, short footage and timely support, and the construction safety is ensured;

step five, after the upper step of the main tunnel is formed, under the condition of a condition, continuing construction for about 20m, stopping construction, and spraying concrete to seal the tunnel face;

and step six, the primary support dismantling and replacing construction of the main tunnel intersection section is the key point of the construction of the newly-added 4# inclined shaft and the main tunnel intersection. The dismounting and replacing section is provided with a bell mouth section and a turning section in a main hole of the cross section of the inclined shaft, and the total length is about 30 m.

2. The method for constructing a small pilot tunnel at a tunnel intersection according to claim 1, comprising a method for constructing a leading small guide pipe, comprising the steps of,

firstly, before a small pilot tunnel arch center is reversely dismantled, phi 42 multiplied by 4 advanced small ducts with the length of 4m are constructed outside the designed excavation contour line of a main tunnel according to the longitudinal 240cm multiplied by the circumferential distance of 40cm, the grouting process is strict, and the tail ends of the advanced small ducts are firmly welded with a steel frame;

and secondly, the steel frame is disassembled and replaced by adopting the principles of weak blasting, short footage, quick sealing and frequent measurement. The steel frame for replacing and disassembling the steel frame should adopt the principles of 'weak blasting, short footage, fast sealing and frequent measurement'. 1 steel frame is disassembled and replaced each time, and weak blasting is combined with disassembling hammers and manual pneumatic pick disassembling and replacing are adopted. Strictly forbidding the simultaneous replacement of a plurality of steel frames of the amplification gun to ensure the construction safety of the intersection section;

and thirdly, in the range of the double-spliced portal, the front hole I14 section steel is connected with the portal by adopting a steel plate and a bolt, the tail end of the front hole I14 section steel is provided with a section steel small bracket for blocking, and the connection of the steel frame and the portal is enhanced. 2 pairs of phi 20 explosive roll foot locking anchor rods with the length of 3m are additionally arranged above the portal frame, and 2 pairs of phi 20 explosive roll foot locking anchor rods with the length of 3m are arranged on two sides of the connecting part of the special-shaped steel frame and the I14 section steel of the main hole.

3. The method as claimed in claim 1, wherein the 1-9 steel frames are deformed steel frames, and the width and height of the steel frames are gradually changed. The 10 th steel frame and the 11 th steel frame are welded in parallel, I22b steel is manufactured outside the steel frames to manufacture door frames, and the door frames are welded with the steel frames firmly.

4. The method as claimed in claim 2, wherein when the main tunnel is reversely converted to the abnormal section, the main tunnel I14 arch is first laid out for measurement, on the right side of the intersection of the main tunnel arch and the small tunnel I14 arch, the anchor rod with the length of 3m for locking feet is drilled on the small tunnel I3578 arch, then the I14 arch under the anchor rod is cut off, the primary support operation such as the installation of the main tunnel I14 arch is carried out in time, the process of removing and converting is used for monitoring the steel frame before the removal and conversion and the steel frame after the removal and conversion of the main tunnel, and the large area collapse of the arch top of the cross section is warned.

5. The method for constructing the small pilot tunnel at the intersection of the tunnel according to claim 1, wherein the monitoring measurement at the main tunnel and the intersection is strengthened in the construction, monitoring measurement points are arranged at the position of the section change and the position of the intersection, an observation point is buried and read in time after each excavation, the initial reading is controlled to be read within 12 hours after the excavation, and the conclusion is obtained through the monitoring data.

6. The construction method of a small pilot tunnel at a tunnel intersection according to claim 1, wherein the length of the slant well is 410m, the slant well intersects with the right hole of the main tunnel at YK42+810, the intersection angle of the bottom reinforcement section and the main tunnel is 60 degrees, the maximum slope is 10 percent, and the slope of the reinforcement section is 2 percent.

7. The method for constructing the small pilot tunnel at the intersection of the tunnel according to claim 1, wherein the main tunnel building has a clear width of 14.75m, a clear height of 5m, a maximum cross-sectional area of 213 square meters, a Turtzite tunnel total length of 10497m, and a maximum buried depth of 639.61 m.

Technical Field

The invention relates to the technical field of tunnel construction, in particular to a tunnel intersection small pilot tunnel construction method.

Background

The national middle and long-term development planning puts the construction of traffic infrastructures at important positions, the gravity center of the construction of major infrastructures is gradually pushed to regions with extremely complex topography and geology, a ten-thousand-meter-level bidirectional six-lane large-section highway tunnel project is or is about to be put into production, an inclined shaft is taken as an auxiliary construction channel of a long tunnel and is one of main modes for accelerating the construction progress, and the intersection of the inclined shaft and a main tunnel has a large section and complex structural stress, so that the inclined shaft is a tunnel construction safety and quality gravity control section. According to the project, the scheme that the small pilot tunnel enters the main tunnel is adopted in construction of the 4# inclined shaft and main tunnel intersection of the Tungzi tunnel, and by means of setting a portal frame, adding locking feet, strengthening advance support, strengthening monitoring and measuring and the like, construction of inclined shaft intersections is completed safely and high-quality, reference is provided for construction of the extremely long-span tunnel inclined shaft intersections in the future, and therefore a small pilot tunnel construction method for the tunnel intersection is provided, and the problems in the background technology are solved.

Disclosure of Invention

The purpose of the invention can be realized by the following technical scheme: a construction method of a small pilot tunnel at a tunnel intersection comprises the following steps:

step one, according to the fact that the intersection angle of the newly-added inclined shaft and the main tunnel is 60 degrees, lining steel frames of the reinforcing section at the bottom end of the newly-added inclined shaft are I14 steel frames, the longitudinal distance is 1.2m, and the lining steel frames belong to class III surrounding rock; the excavation width of the reinforcement section of the newly added inclined shaft is 11.16m, and the width of the intersection section of the inclined shaft and the main tunnel is 12.89 m; the steel frame spacing of the steel frame is required to be adjusted in the steering of the steel frame at the bottom end of the inclined shaft, the steel frame spacing at the right side of the inclined shaft hole is set according to 1.2 m/pin, the steel frame spacing at the left side of the inclined shaft hole is set according to 1.8 m/pin, and the steel frame of the inclined shaft is gradually steered from the direction perpendicular to the central line of the inclined shaft to the direction parallel to the central line of the main hole through the adjustment of 10 steel frames;

and step two, the portal is used as a stress supporting platform of the main tunnel steel frame. The door frame is formed by combining, welding and processing double-spliced I22b steel frames. When the inclined shaft is constructed to the 10 th arch frame at the bottom end, firstly digging and installing a double-spliced I22 type steel arch frame, after the arch frame is installed, constructing the 10 th arch frame at the bottom end of the inclined shaft, and firmly welding the arch frame with the double-spliced arch frame, respectively arranging a pair of locking anchor rods at the middle part of the arch frame for welding and fixing, and welding the top parts of the inclined shaft arch frame and the double-spliced type steel arch frame by adopting I22 type steel;

and step three, adopting an I14 steel frame as the steering primary support of the inclined shaft section, and performing tunneling steering on the inclined shaft full section. The outer side length of the turning section is 19m, the inner side length of the turning section is 7m, the turning is finished according to 10 steel frames, the distance between the outer side steel frames is 10 multiplied by 1.9m, the distance between the inner side steel frames is 10 multiplied by 0.7m, and the arch crown elevation is gradually raised in the turning stage to be consistent with the height of the top of the main tunnel;

fourthly, bell mouth expanding excavation is finished by 6I 14 steel primary support steel frames, the bell mouth expanding excavation length is 5m, 6 steel frames are totally used, the distance is 1.0m, the 6 th steel frame is expanded to the normal section of the upper step of the main tunnel, the expanding excavation section adopts weak blasting, short footage and timely support, and the construction safety is ensured;

step five, after the upper step of the main tunnel is formed, under the condition of a condition, continuing construction for about 20m, stopping construction, and spraying concrete to seal the tunnel face;

and step six, the primary support dismantling and replacing construction of the main tunnel intersection section is the key point of the construction of the newly-added 4# inclined shaft and the main tunnel intersection. The dismounting and replacing section is provided with a bell mouth section and a turning section in a main hole of the cross section of the inclined shaft, and the total length is about 30 m.

Preferably, the construction method of the advanced small conduit comprises the following steps,

firstly, before a small pilot tunnel arch center is reversely dismantled, phi 42 multiplied by 4 advanced small ducts with the length of 4m are constructed outside the designed excavation contour line of a main tunnel according to the longitudinal 240cm multiplied by the circumferential distance of 40cm, the grouting process is strict, and the tail ends of the advanced small ducts are firmly welded with a steel frame;

and secondly, the steel frame is disassembled and replaced by adopting the principles of weak blasting, short footage, quick sealing and frequent measurement. The steel frame for replacing and disassembling the steel frame should adopt the principles of 'weak blasting, short footage, fast sealing and frequent measurement'. 1 steel frame is disassembled and replaced each time, and weak blasting is combined with disassembling hammers and manual pneumatic pick disassembling and replacing are adopted. Strictly forbidding the simultaneous replacement of a plurality of steel frames of the amplification gun to ensure the construction safety of the intersection section;

and thirdly, in the range of the double-spliced portal, the front hole I14 section steel is connected with the portal by adopting a steel plate and a bolt, the tail end of the front hole I14 section steel is provided with a section steel small bracket for blocking, and the connection of the steel frame and the portal is enhanced. 2 pairs of phi 20 explosive roll foot locking anchor rods with the length of 3m are additionally arranged above the portal frame, and 2 pairs of phi 20 explosive roll foot locking anchor rods with the length of 3m are arranged on two sides of the connecting part of the special-shaped steel frame and the I14 section steel of the main hole, so that the complete stress of the arch frame is ensured.

Preferably, the 1-9 steel frames are variable-section special-shaped steel frames, and the width and the height of the steel frames are gradually changed. The 10 th steel frame and the 11 th steel frame are welded in parallel, I22b steel is manufactured outside the steel frames to manufacture door frames, and the door frames are welded with the steel frames firmly.

Preferably, when the main tunnel is reversely dismantled and replaced to the steering special-shaped section, firstly, the main tunnel I14 arch centering measurement lofting is carried out, a phi 20 explosive roll locking anchor rod with the length of 3m is arranged on the right side of the intersection of the small guide tunnel arch centering and the main tunnel arch centering, then, an I14 arch centering below the locking anchor rod is cut off, primary support operations such as installation of the main tunnel I14 arch centering are carried out in time, the steel frame before dismantling and replacing and the steel frame after dismantling and replacing the main tunnel are monitored together in the chiseling dismantling and replacing process, the arch crown of the cross section is warned to collapse in a large area, and construction quality and safety in the chiseling dismantling and replacing process are guaranteed.

Preferably, monitoring measurement is enhanced at the main tunnel and the intersection in construction, monitoring measurement points are arranged at the cross section change position and the intersection position, observation points are buried and read in time after each excavation, initial reading is controlled to be read within 12 hours after excavation, and a conclusion is obtained through monitoring data; monitoring measurement data of the intersection of the newly-added 4# inclined shaft and the main hole meet the standard design requirement, cracking is not found in primary support, single variable quantity, accumulated variable quantity and change rate of vault settlement and peripheral convergence are all within the control value range, and early warning values are not exceeded.

Preferably, the length of the inclined shaft is 410m, the inclined shaft intersects with the right hole of the main hole at YK42+810, the intersection angle of the bottom reinforced section and the main hole is 60 degrees, the maximum gradient is 10 percent, and the gradient of the reinforced section is 2 percent.

Preferably, the limit of the main tunnel building is 14.75m in clear width and 5m in clear height, the maximum cross-sectional area reaches 213 square meters, the total length of the Turtumla tunnel is 10497m, and the maximum buried depth is 639.61 m.

The invention has the beneficial effects that:

1. the construction technology for reinforcing and supporting the steel arch frame of the main tunnel into the main tunnel by matching the tunnel inclined shaft joist portal frame with the foot locking anchor rod and the advanced small guide pipe is introduced in detail, and a reference basis is provided for the construction of the inclined shaft small guide hole into the tunnel of the similar large-section tunnel;

2. the construction safety of the gas section of the tunnel is improved while the pressure of the construction period of the main tunnel is relieved;

3. the method introduces the means of double-spliced portal frames, increased locking feet, advanced support enhancement, monitoring measurement enhancement and the like at the cross section of the 4# inclined shaft and the main tunnel of the tung catalpa tunnel in detail, completes the construction of the inclined shaft intersection with high safety and high quality, meets the requirement of assisting the main tunnel construction, and can provide reference for the construction of the inclined shaft intersection of the extra-long-span tunnel in the future.

Drawings

The invention will be further described with reference to the accompanying drawings.

FIG. 1 is a schematic view of the construction process of the present invention;

FIG. 2 is a schematic view of a section steel turn of a newly added 4# inclined shaft and main tunnel intersection of the invention;

FIG. 3 is a schematic view of the installation of a 4# slant well portal of the present invention;

FIG. 4 is another schematic view of the installation of the new 4# slant well door frame of the present invention;

FIG. 5 is a schematic view of a steering and steering steel frame in a main tunnel of a newly added 4# inclined shaft according to the present invention;

FIG. 6 is a schematic view of the advanced ductwork installation of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-6, the present invention provides a technical solution: a construction method of a small pilot tunnel at a tunnel intersection comprises the following steps:

step one, according to the fact that the intersection angle of the newly-added inclined shaft and the main tunnel is 60 degrees, lining steel frames of the reinforcing section at the bottom end of the newly-added inclined shaft are I14 steel frames, the longitudinal distance is 1.2m, and the lining steel frames belong to class III surrounding rock; the excavation width of the reinforcement section of the newly added inclined shaft is 11.16m, and the width of the intersection section of the inclined shaft and the main tunnel is 12.89 m; the steel frame spacing of the steel frame is required to be adjusted in the steering of the steel frame at the bottom end of the inclined shaft, the steel frame spacing at the right side of the inclined shaft hole is set according to 1.2 m/pin, the steel frame spacing at the left side of the inclined shaft hole is set according to 1.8 m/pin, and the steel frame of the inclined shaft is gradually steered from the direction perpendicular to the central line of the inclined shaft to the direction parallel to the central line of the main hole through the adjustment of 10 steel frames;

secondly, the portal is used as a stress supporting platform of the main tunnel steel frame; the door frame is formed by combining, welding and processing double-spliced I22b steel frames; the portal frame is used as a supporting platform of a right steel frame foot of the main tunnel, bears the pressure of surrounding rocks and steel frames, and a foot locking anchor rod and a primary support process are strictly performed according to requirements; when the inclined shaft is constructed to the 10 th arch frame at the bottom end, firstly digging and installing a double-spliced I22 type steel arch frame, after the arch frame is installed, constructing the 10 th arch frame at the bottom end of the inclined shaft, and firmly welding the arch frame with the double-spliced arch frame, respectively arranging a pair of locking anchor rods at the middle part of the arch frame for welding and fixing, and welding the top parts of the inclined shaft arch frame and the double-spliced type steel arch frame by adopting I22 type steel;

and step three, adopting an I14 steel frame as the steering primary support of the inclined shaft section, and performing tunneling steering on the inclined shaft full section. The outer side length of the turning section is 19m, the inner side length of the turning section is 7m, the turning is finished according to 10 steel frames, the distance between the outer side steel frames is 10 multiplied by 1.9m, the distance between the inner side steel frames is 10 multiplied by 0.7m, and the arch crown elevation is gradually raised in the turning stage to be consistent with the height of the top of the main tunnel;

fourthly, bell mouth expanding excavation is finished by 6I 14 steel primary support steel frames, the bell mouth expanding excavation length is 5m, 6 steel frames are totally used, the distance is 1.0m, the 6 th steel frame is expanded to the normal section of the upper step of the main tunnel, the expanding excavation section adopts weak blasting, short footage and timely support, and the construction safety is ensured;

step five, after the upper step of the main tunnel is formed, under the condition of a condition, continuing construction for about 20m, stopping construction, and spraying concrete to seal the tunnel face;

and step six, the primary support dismantling and replacing construction of the main tunnel intersection section is the key point of the construction of the newly-added 4# inclined shaft and the main tunnel intersection. The dismounting and replacing section is provided with a bell mouth section and a turning section in a main hole of the cross section of the inclined shaft, and the total length is about 30 m.

A construction method of a leading small conduit comprises the following steps,

firstly, before a small pilot tunnel arch center is reversely dismantled, phi 42 multiplied by 4 advanced small ducts with the length of 4m are constructed outside the designed excavation contour line of a main tunnel according to the longitudinal 240cm multiplied by the circumferential distance of 40cm, the grouting process is strict, and the tail ends of the advanced small ducts are firmly welded with a steel frame;

and secondly, the steel frame is disassembled and replaced by adopting the principles of weak blasting, short footage, quick sealing and frequent measurement. The steel frame for replacing and disassembling the steel frame should adopt the principles of 'weak blasting, short footage, fast sealing and frequent measurement'. 1 steel frame is disassembled and replaced each time, and weak blasting is combined with disassembling hammers and manual pneumatic pick disassembling and replacing are adopted. Strictly forbidding the simultaneous replacement of a plurality of steel frames of the amplification gun to ensure the construction safety of the intersection section;

and thirdly, in the range of the double-spliced portal, the front hole I14 section steel is connected with the portal by adopting a steel plate and a bolt, the tail end of the front hole I14 section steel is provided with a section steel small bracket for blocking, and the connection of the steel frame and the portal is enhanced. 2 pairs of phi 20 explosive roll foot locking anchor rods with the length of 3m are additionally arranged above the portal frame, and 2 pairs of phi 20 explosive roll foot locking anchor rods with the length of 3m are arranged on two sides of the connecting part of the special-shaped steel frame and the I14 section steel of the main hole, so that the complete stress of the arch frame is ensured.

1-9 steel frames are deformed cross-section and deformed steel frames, and the width and height of the steel frames are gradually changed. The 10 th steel frame and the 11 th steel frame are welded in parallel, I22b steel is manufactured outside the steel frames to manufacture door frames, and the door frames are welded with the steel frames firmly.

When the main tunnel is reversely dismantled and changed to a steering special-shaped section, firstly, the main tunnel I14 arch centering measurement lofting is carried out, after a phi 20 explosive roll foot locking anchor rod with the length of 3m is arranged on the right side of the intersection of the small pilot tunnel arch centering and the main tunnel arch centering, the I14 arch centering below the foot locking anchor rod is cut off, primary support operations such as installation of the main tunnel I14 arch centering are carried out in time, the steel frame before dismantling and changing and the steel frame after dismantling and changing the main tunnel are monitored together in the process of dismantling and changing, the vault collapse of the cross section is warned, and the construction quality and safety in the process of dismantling and changing are ensured; the reserved settling amount of the steel arch centering in the main tunnel is properly increased within the triangular area, and is preferably controlled within 10-15 cm; excavation in the range of the profile steel frame on the right side of the main tunnel is difficult to drill holes, excavation is divided into multiple times, trimming is gradually carried out in place, long holes are forbidden to be drilled, more chemicals are filled, the stability of surrounding rocks is damaged, overexcavation is caused, and top collapse is caused in serious cases.

Monitoring measurement at the main tunnel and the intersection is enhanced in construction, monitoring measurement points are uniformly arranged at the position of a section change and the position of the intersection, observation points are buried and read in time after each excavation, initial reading is controlled to be read within 12 hours after the excavation, and a conclusion is obtained through monitoring data; monitoring measurement data of the intersection of the newly-added 4# inclined shaft and the main hole meet the standard design requirement, cracking is not found in primary support, single variable quantity, accumulated variable quantity and change rate of vault settlement and peripheral convergence are all within the control value range, and early warning values are not exceeded.

The length of the inclined shaft is 410m, the inclined shaft intersects with the right hole of the main hole at YK42+810, the intersection angle of the bottom reinforced section and the main hole is 60 degrees, the maximum gradient is 10 percent, and the gradient of the reinforced section is 2 percent.

The main tunnel building clearance is 14.75m in clear width and 5m in clear height, the maximum section area reaches 213 square meters, the total length of a Turtdy tunnel is 10497m, the maximum buried depth is 639.61m, the Turtdy tunnel belongs to a high gas tunnel, the construction of the No. 4 inclined shaft of the Turtdy tunnel and the intersection of the main tunnel is reinforced for ventilation, a wind tube can be connected to the portal of the inclined shaft at the intersection for construction ventilation and can be gradually closely followed along with the turning of small-section construction, and a plurality of local fans are also required to be arranged to reinforce ventilation for the erection of local fans at ventilation blind spots, leeward places and the like, so that no dead angle is ensured, and gas gathering is; continuous and uninterrupted ventilation is guaranteed in the tunnel construction process, the air volume and the air pressure meet the requirements of specifications and scheme design, and air can not be stopped randomly.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.