Construction method for acute angle oblique crossing single-head tunneling reverse ventilation of pilot tunnel and main tunnel

Abstract

The invention belongs to a construction method for reverse ventilation of pilot tunnel and front tunnel acute angle oblique crossing single-head tunneling. In a pilot tunnel construction section, a mode of combining press-in type ventilation and air draft generated by an air draft chimney is adopted for ventilation and dust discharge; ventilation and dust discharge are performed when the pilot tunnel enters the main tunnel within 30 m for construction in a manner of combining press-in ventilation with air draft force generated by an air draft chimney and air exhaust by an air exhaust barrel of a main exhaust fan; ventilation and dust removal for main tunnel construction with the distance larger than 30 m are achieved in the mode that press-in type ventilation, air draft force generated by an air draft chimney, air exhaust of an air exhaust barrel of a main exhaust fan and isolation of a tunnel face construction area through a movable dust isolation wall are combined. The method can ensure that polluted air in a large-area main tunnel can be effectively discharged from a small-area pilot tunnel when the pilot tunnel and the main tunnel are subjected to acute-angle oblique crossing single-head tunneling, so that the construction environment in the main tunnel is better ensured, the construction efficiency is improved, and the method has the advantages of high construction efficiency, low comprehensive cost and remarkable purification effect.

Description

Technical Field

[0001] The invention belongs to a construction method for reverse ventilation of a single-head excavation with a pilot tunnel and a main tunnel at an acute angle. Background Art

[0002] At present, most of the ventilation methods used in China for tunnel construction ventilation are to supply air into the tunnel through air compressors and air ducts to blow the polluted air generated by the face construction out of the tunnel. This ventilation effect is greatly affected by the ventilation distance. The longer the ventilation distance, the worse the ventilation effect. During ventilation, the polluted air diffuses throughout the tunnel and is then discharged from the guide tunnel (or inclined shaft), causing the polluted air generated by the face construction to spread and pollute all parts of the tunnel, resulting in serious air pollution and poor construction conditions. Especially when entering the main tunnel through the pilot tunnel for construction, if the pilot tunnel and the main tunnel are obliquely intersected at an acute angle, and the intersection angle is less than 90° to form an acute angle, due to the acute angle of the intersection, a construction environment with weak air circulation in the acute angle area is formed, which is even more unfavorable for air circulation. For example, the excavation contour of the inclined shaft of Qingshiling Tunnel in the LJ-9 contract section of Baoji to Pingkan Expressway in Shaanxi Province is 7.03m high and 11.1m wide; the excavation contour of the main tunnel of Qingshiling Tunnel is 9.50m high and 19.30m wide. The pilot tunnel and the main tunnel are obliquely intersected at an acute angle and single-head excavation is adopted. When entering the single-head excavation tunnel from the pilot tunnel, the polluted air in a large area of ​​the tunnel is difficult to be discharged than that in a small area of ​​the pilot tunnel, which makes the air pollution in the tunnel more serious and endangers the health of construction workers.

[0003] Therefore, there is an urgent need for an effective method for ventilation and dust removal for single-head excavation with acute angles between the pilot tunnel and the main tunnel. Summary of the invention

[0004] The object of the present invention is to provide a construction method for reverse ventilation of a single-head excavation with a guide tunnel and a main tunnel at an acute angle, so as to solve the problems raised in the above-mentioned background technology.

[0005] To this end, a construction method for reverse ventilation with single-head excavation at an acute angle between the pilot tunnel and the main tunnel is provided, comprising the following steps: (1) An exhaust chimney is set up near the side of the pilot tunnel entrance. The height of the exhaust chimney is greater than 30m. An air inlet is set on both sides of the bottom of the exhaust chimney. One end of the exhaust pipe is connected to an air inlet of the exhaust chimney. The other end of the exhaust pipe is installed along the upper end wall away from the acute angle of the pilot tunnel to 15m away from the pilot tunnel face and is synchronously followed as the pilot tunnel construction face advances; One end of the exhaust duct is connected to another air inlet of the extraction chimney, and the other end of the exhaust duct is hung along the lower part of the exhaust duct on the upper end wall of the side away from the acute angle bevel of the guide tunnel and communicates with the air outlet of the main exhaust fan in the guide tunnel or the main tunnel; (2) Ventilation and dust removal during the pilot tunnel construction section: A combination of forced-in ventilation and exhaust chimneys are used to generate exhaust force during the pilot tunnel construction section; (a) Within 25 m of the pilot tunnel excavation, an air compressor is set up outside the pilot tunnel entrance. During the construction of the pilot tunnel, an axial flow air compressor is used to connect a 1.5 m diameter flexible air duct section I to press air towards the pilot tunnel face, and the foul air is discharged outside the tunnel through the construction pilot tunnel; (b) When the pilot tunnel excavation is more than 25 m, an air compressor is set up outside the tunnel entrance. During the construction of the pilot tunnel, an axial flow air compressor is used to connect a 1.5 m diameter flexible air duct section I to press air towards the pilot tunnel face, and the foul air is discharged outside the tunnel through the construction pilot tunnel. The flexible air duct section I is hung along the upper inner side of the acute-angled hypotenuse of the pilot tunnel through a support frame; The inner end of the exhaust duct is hung along the upper outer side of the acute-angled hypotenuse away from the pilot tunnel entrance to a position 15 m away from the pilot tunnel face and follows up synchronously with the advancement of the construction face. The extraction chimney generates an extraction force to extract the polluted air in the pilot tunnel at one end of the exhaust duct without power; (3) For the ventilation and dust removal during the construction within 30 m of the pilot tunnel entering the main tunnel, a combined method of forced ventilation, using the extraction force generated by the extraction chimney for extraction, and exhausting air through the main exhaust fan exhaust duct is adopted; (a) Layout of the flexible air duct. An air compressor is erected at the pilot tunnel entrance to press air into the tunnel. An axial flow air compressor is used to connect a 1.5 m diameter flexible air duct to press air towards the pilot tunnel face. The flexible air duct is longitudinally laid in sections as the excavation face advances. The flexible air duct section I is hung along the upper inner side of the acute-angled hypotenuse of the pilot tunnel entrance. After the flexible air duct enters the main tunnel, the flexible air duct section II is hung along the upper inner side of the main tunnel by continuously correcting in the advancing direction of the main tunnel excavation. Then, the flexible air duct sections III and IV are successively corrected and hung in the advancing direction of the main tunnel excavation until the flexible air duct section V is hung when the direction of the flexible air duct is corrected to meet the ventilation requirements of the main tunnel; (b) Layout of the exhaust duct. An exhaust widening area is set at the acute-angled oblique intersection of the pilot tunnel and the main tunnel. The inner end extraction opening of the exhaust duct is finally located on the upper end wall of the exhaust widening area at the acute-angled oblique intersection of the pilot tunnel and the main tunnel. The extraction chimney generates an extraction force to extract the polluted air in the pilot tunnel and the main tunnel at the inner end of the exhaust duct without power and discharges it outside the tunnel through the extraction chimney; (c) Layout of the exhaust fan duct. A main exhaust fan is set on the middle wall of the exhaust widening area. The air inlet of the main exhaust fan faces the main tunnel face. When necessary, the main exhaust fan is started to discharge the polluted air in the pilot tunnel and the main tunnel outside the tunnel through the air outlet of the main exhaust fan, the exhaust duct, and the extraction chimney; (4) For the ventilation and dust removal during the construction of the main tunnel more than 30 m away, a combined method of forced ventilation, using the extraction force generated by the extraction chimney for extraction, exhausting air through the main exhaust fan exhaust duct, and isolating the construction area of the tunnel face with a mobile dust isolation wall is adopted; (a) Assemble the mobile dust isolation wall in the main tunnel. The mobile dust isolation wall is set at a distance of 20 - 25 m from the main tunnel face. The mobile dust isolation wall isolates the construction area of the main tunnel face and advances synchronously with the excavation of the main tunnel face; (b) The exhaust port at the inner end of the exhaust duct is located on the upper end wall of the exhaust widening area at the acute angle of the guide tunnel and the main tunnel. The exhaust chimney generates exhaust force to unpoweredly extract the polluted air in the guide tunnel and the main tunnel at the inner end of the exhaust duct and discharge it out of the tunnel through the exhaust chimney; (c) Extend the soft air belt pipeline V segment to the soft air belt outlet, pass through the movable dust isolation wall to the outer edge of the main tunnel face construction area, and advance synchronously with the excavation of the main tunnel face; (d) As the construction face advances, the main exhaust fan moves forward to a position 30m away from the main tunnel face. The exhaust duct pipeline is correspondingly extended to connect to the main exhaust fan outlet. The main exhaust fan inlet is connected to the space between the movable dust-proof wall and the face through another section of exhaust duct. A booster exhaust fan is installed at the original position of the main exhaust fan. The outlet of the booster exhaust fan is introduced into the return air flow of the exhaust duct pipeline. The exhaust duct pipeline is always located on the upper end wall on the side away from the pilot tunnel or the main tunnel through the support frame; (5) An additional axial flow compressor fan is installed at 50-55m of each extended soft air belt pipeline V section to enhance the air supply force of the soft air belt pipe, and a booster exhaust fan is installed at 60-65m of each extended exhaust pipe pipeline to enhance the dust removal function of the tunnel face construction area and the main tunnel; (6) Repeat steps (4) and (5) until the main hole is connected.

[0006] As a further description of the above technical solution: the air compressor is located 5 to 8 meters outside the guide tunnel opening to ensure that the air pressure into the guide tunnel will not be affected by the exhaust air.

[0007] As a further description of the above technical solution: the movable dust-proof wall is two door frames arranged at a distance from each other on the left and right sides, the upper ends of the two door frames are respectively fixed to the two ends of the lower part of the upper beam frame as a whole, the lower ends of the two door frames are respectively fixed to the middle part of the upper end of a steel seesaw as a whole, the two ends of the upper part of the steel seesaw and the corresponding lower part of the door frame are provided with oblique support rods, a reel roller is provided in the middle part of the upper beam frame, the reels in the middle of the two ends of the reel roller are respectively connected to the motor shaft of the reel motor located at the two ends of the upper beam frame, the inner sides of the two door frames on both sides of the lower end of the reel roller are correspondingly provided with concave sliding grooves for curtain doors, and the rolling shutter door The upper end is fixed to the winding roller, and the two sides of the rolling shutter door are slidably fitted in the concave sliding grooves of the curtain door on the corresponding sides. The lower end of the rolling shutter door is connected to the curtain door bottom plate which is slidably fitted in the concave sliding grooves of the curtain door. The inflatable bag wall is semicircular, and a rectangular opening groove is provided in the middle of the straight edge of the inflatable bag wall. The three sides of the rectangular opening groove of the inflatable bag wall are respectively connected to the outer sides of the corresponding two door frames and the upper sides of the door frames. Exhaust holes for exhaust pipes to pass through and air supply holes for soft air belts to pass through are respectively provided on the inflatable bag walls on both sides of the rectangular opening groove. An inflator is provided at the lower ends of the two door frames, and the inflation port of the inflator is communicated with the air inlet of the inflatable bag wall.

[0008] As a further description of the above technical solution: the diameter of the wind extraction chimney is 1.6-2m, and it stands vertically and fixedly according to the mountain terrain.

[0009] As a further description of the above technical solution: The exhaust duct is a sheet metal duct or a plastic synthetic material duct with a diameter of 1 m, and the exhaust air duct is a sheet metal duct or a plastic synthetic material duct with a diameter of 1.2 m.

[0010] As a further description of the above technical solution: In the middle of the casing of the booster exhaust fan, a motor is provided through a motor bracket. An exhaust air blade is provided on the motor shaft. An air inlet is provided at the front end of the casing. An air outlet duct is provided at the upper end of the rear part of the casing or on the upper part of the side surface away from the heading face. An arc-shaped deflector inclined towards the air outlet is provided on the inner wall of the casing at the rear side of the motor. A one-way valve is provided at the air outlet. The air outlet communicates with the inside of the lower part of the exhaust air duct through a guide duct. An arc-shaped air guide plate is provided in the exhaust air duct on the downwind side of the air outlet of the guide duct. A one-way valve is provided in the exhaust air duct at the front end of each booster exhaust fan.

[0011] As a further description of the above technical solution: The support frame is a triangular frame, and the triangular frame is fixed on the pilot tunnel or the main tunnel wall through rock bolts. A semi-circular upward-opening ring frame is provided at the upper end of the triangular frame.

[0012] As a further description of the above technical solution: When the flexible air duct enters the main tunnel from the pilot tunnel, there is a high difference point. The flexible air duct across the high difference point is a straight section to ensure sufficient air pressure supply.

[0013] As a further description of the above technical solution: The correction angle from the first section to the second section of the flexible air duct should maintain a large obtuse angle, so that the second section of the flexible air duct has a longer usable length.

[0014] As a further description of the above technical solution: The clear height of the flexible air duct, the exhaust duct and the exhaust air duct from the ground is mainly to ensure the normal passage of vehicles below.

[0015] The present invention has the following advantages and positive effects compared with the prior art: (1) The present invention can ensure that when a pilot tunnel intersects with the main tunnel at an acute angle and is driven in a single heading, the polluted air in the large - area main tunnel can be effectively discharged from the small - area pilot tunnel, which further guarantees the construction environment in the main tunnel, improves the construction efficiency, and has the advantages of high construction efficiency, low comprehensive cost, and remarkable purification effect. During the tunnel construction process of the acute - angle oblique intersection of the pilot tunnel and the main tunnel with single - heading driving, the present invention respectively adopts: installing a chimney for exhausting air beside the side close to the pilot tunnel entrance, and the air outlets of the air extraction duct and the exhaust duct, which are connected to both the pilot tunnel and the main tunnel, are respectively connected to the two sides inside the bottom of the chimney for exhausting air. By means of the chimney for exhausting air and the air extraction duct, the polluted air in the pilot tunnel and the main tunnel is drawn into the chimney for exhausting air without power throughout the day for dust removal or enhancing the dust removal effect of the exhaust duct; in the construction section of the pilot tunnel, a combined ventilation and dust removal method of forced ventilation and air extraction by the chimney for exhausting air is adopted; for the ventilation and dust removal during the construction within 30 m of the pilot tunnel entering the main tunnel, a combined method of forced ventilation, air extraction by the chimney for exhausting air, and air exhaust by the main exhaust fan duct is adopted; for the ventilation and dust removal during the construction of the main tunnel more than 30 m away, a combined method of forced ventilation, air extraction by the chimney for exhausting air, air exhaust by the main exhaust fan duct, and isolation of the heading face construction area by a movable dust - proof wall is adopted.

[0016] The present invention enables the clean air and the polluted air in the tunnel to flow orderly in separate channels, ensuring excellent air purification effect in the tunnel and effectively protecting the occupational health of the operators.

[0017] (2) The present invention can ensure excellent air quality in the tunnel. Tests show that during the construction in the tunnel of the present invention, the air quality in the tunnel is as follows: nitrogen oxides (NO2): time - weighted average allowable concentration is 4.0 - 4.1 mg / m 3 ; methane (CH4) concentration is less than 0.2%; carbon monoxide (CO) 24 - hour average concentration is 8 - 9 ppm; sulfur dioxide (SO2): TWA is less than 3 mg / m 3 ; hydrogen sulfide (H2S) concentration is less than 2 mg / m 3 ; respirable dust concentration is less than 1 mg / m 3 ; there is no obvious dust raising visually in the tunnel; temperature is 25 - 26.5 °C 0 , oxygen content is 21.5 - 21%, the fresh air supply per person is greater than 3 m 3 / min, the air quality index (AQI) in the tunnel is 51 - 55, and the air quality in the tunnel is excellent. While the air quality index (AQI) of the traditional construction method is 175 - 250, and the air quality in the tunnel is moderately to severely polluted. The present invention is conducive to reducing the air index in the tunnel and is beneficial to the health of construction workers.

[0018] (3) The present invention has the advantages of simple structure, easy installation and disassembly, labor - saving and time - saving during construction, fast speed, material saving, cost saving, saving construction period, and strong practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the overall structural schematic diagram of the pilot tunnel and the main tunnel construction sections of the present invention; Figure 2 This is the structural schematic diagram of the soft air duct layout for the pilot tunnel to enter the main tunnel of the present invention; Figure 3 This is the structural schematic diagram of the mobile dust partition wall of the present invention; Figure 4 This is the structural schematic diagram of the booster exhaust fan of the present invention; Figure 5 This is the structural schematic diagram of the air outlet of the booster exhaust fan of the present invention leading into the exhaust duct; Figure 6 This is the structural schematic diagram of the support frame of the present invention; Figure 7 is Figure 6 the right side structural schematic diagram of; Figure 8 This is the structural schematic diagram of the additional axial flow compressor of the present invention. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments. However, the following embodiments are only the preferred embodiments of the present invention, not all of them. Based on the embodiments in the implementation manners, other embodiments obtained by those skilled in the art without making creative efforts all belong to the protection scope of the present invention. The construction methods in the following embodiments are all conventional methods unless otherwise specified. The materials, devices, equipment, etc. used in the following embodiments can all be obtained from commercial channels unless otherwise specified.

[0021] As Figure 1 shown, in the implementation of the present invention in the Qingshiling Tunnel of the 9th contract section of the Baoji to Pingkan Expressway in Shaanxi Province, the excavation profile height of the pilot tunnel 9 is 7.03 m and the width is 11.1 m; the excavation profile height of the main tunnel 2 of the Qingshiling Tunnel is 9.50 m and the width is 19.30 m. The pilot tunnel and the main tunnel are obliquely intersected at an acute angle and driven by a single head, and the intersection angle is less than 90° to form an acute angle, resulting in a construction environment with weak air circulation in the acute angle area, which is not conducive to air circulation. When entering the main tunnel section 1 of the single-heading tunnel from the pilot tunnel, on one side of the main tunnel is the unexcavated area 7, and it is difficult for the polluted air in the large area of the main tunnel to be discharged through the small area of the pilot tunnel 9. Using the traditional method of blowing air and removing dust will cause serious air pollution in the tunnel and endanger the health of construction workers.

[0022] The construction ventilation method of the present invention is adopted, which effectively improves the overall construction environment of the tunnel, guarantees the occupational health of the operators, reduces the construction safety risks, improves the tunnel construction efficiency, and simultaneously enhances the environmental protection during the tunnel construction process.

[0023] As Figures 1 to 8 shown, a ventilation and dust removal method for the single-heading construction of long inclined shafts and extra-long tunnels includes the following steps: As Figure 1 shown, (1) A chimney 16 for exhausting air is arranged beside the side close to the portal of the pilot tunnel. The height of the chimney for exhausting air is greater than 30 m, the diameter of the chimney for exhausting air is 1.6 - 2 m, and it is vertically fixed and erected according to the mountain terrain. One air inlet is respectively arranged at the bottom of the chimney for exhausting air on both sides. One end of the air extraction duct 18 is connected to one air inlet of the chimney 16 for exhausting air, and the other end of the air extraction duct follows the upper end wall on the side far from the acute-angled hypotenuse of the pilot tunnel to a position 15 m away from the face of the pilot tunnel and synchronously advances as the face of the pilot tunnel construction progresses. The air extraction duct is a sheet iron duct or a plastic composite material duct with a diameter of 1 m.

[0024] One end of the exhaust air duct 12 is connected to the other air inlet of the chimney 16 for exhausting air, and the other end of the exhaust air duct 12 is hung along the lower part of the air extraction duct on the upper end wall on the side far from the acute-angled hypotenuse of the pilot tunnel and communicates with the air outlet of the main exhaust fan in the pilot tunnel or the main tunnel. The exhaust air duct is a sheet iron duct or a plastic composite material duct with a diameter of 1.2 m.

[0025] (2) Construction ventilation and dust removal in the pilot tunnel construction section: A combined method of forced ventilation and air extraction by the chimney for exhausting air is adopted in the pilot tunnel construction section; (a) Within 25 m of the pilot tunnel excavation, an air compressor 6 is arranged outside the portal of the pilot tunnel. The air compressor 6 can be an axial flow air compressor. During the construction of the pilot tunnel, a section I of a flexible air duct 8 with a diameter of 1.5 m is connected to an axial flow air compressor to press air towards the face of the pilot tunnel. The air outlet of the flexible air duct 8 is arranged at a position 15 m away from the face. The clean air pressed in by the air compressor discharges the turbid air in the pilot tunnel out of the tunnel through the construction pilot tunnel.

[0026] (b) When the pilot tunnel excavation is more than 25 m, an air compressor is arranged outside the portal. During the construction of the pilot tunnel, a section I of a flexible air duct is connected to an axial flow air compressor to press air towards the face of the pilot tunnel. The turbid air is discharged out of the tunnel through the construction pilot tunnel. The section I of the flexible air duct is hung along the upper part inside the acute-angled hypotenuse of the pilot tunnel through a support frame 14.

[0027] The inner end of the air extraction duct 18 is hung along the upper part outside the acute-angled hypotenuse far from the portal of the pilot tunnel to a position 15 m away from the face of the pilot tunnel and synchronously advances as the face of the construction progresses. The chimney for exhausting air generates an air extraction force to extract the polluted air at one end of the air extraction duct without power. The flexible air duct and the air extraction duct are separately arranged on the upper part of the side walls on both sides of the pilot tunnel or the main tunnel.

[0028] (3) For the ventilation and dust removal during the construction within 30 m from the pilot tunnel to the main tunnel, a combined method of forced ventilation, suction generated by a chimney for exhaust, and exhaust through the exhaust duct of the main exhaust fan is adopted. (a) Eight flexible air ducts are arranged. An air compressor is erected at the pilot tunnel entrance to press air into the tunnel. The air compressor is located 5 - 8 m outside the pilot tunnel entrance to ensure that the incoming air in the pilot tunnel is not affected by the exhausted air. An axial flow air compressor is used to connect a flexible air duct with a diameter of 1.5 m to press air towards the face of the pilot tunnel. The flexible air duct is longitudinally arranged in segments as the tunneling face advances. The first segment of the flexible air duct is hung along the upper inner side of the acute-angled hypotenuse of the pilot tunnel entrance. After the flexible air duct enters the main tunnel, the second segment of the flexible air duct is hung along the upper inner side of the main tunnel by continuously correcting the direction towards the tunneling direction of the main tunnel. Then, the third and fourth segments of the flexible air duct are successively corrected and hung towards the tunneling direction of the main tunnel. The fifth segment of the flexible air duct is hung until the direction of the flexible air duct is corrected to meet the ventilation requirements along the main tunnel. The correction angle from the first segment to the second segment of the flexible air duct should maintain a large obtuse angle to ensure a longer usable length of the second segment of the flexible air duct and minimize the ventilation loss caused by the turning angle. The third and fourth segments of the flexible air duct are mainly for correction and transition to ensure that the flexible air duct transitions from the transverse direction of the main tunnel of the second segment to the longitudinal flexible air duct of the fifth segment of the main tunnel, so as to ensure smooth ventilation and minimum loss.

[0029] As Figure 2 shown, when the flexible air duct 8 enters the main tunnel from the pilot tunnel, there will be a high and low point 13. The flexible air duct crossing the high and low point is a straight section to ensure sufficient air pressure supply.

[0030] (b) Arrangement of the exhaust duct 18. An exhaust widening area 11 is set at the acute-angled oblique intersection of the pilot tunnel and the main tunnel. The exhaust widening area is 7 m long and 3 m wide. This is the area with the worst air quality in the main tunnel. The clean air pressed into the main tunnel returns the polluted air at the face to the intersection. However, due to the acute angle of the intersection, it is not conducive to air circulation, so the polluted air accumulates here. Due to the acute-angled oblique intersection of the inclined shaft pilot tunnel and the main tunnel, large vehicles need to adjust their directions at the intersection, occupying a relatively large driving area. The widened area at the acute-angled oblique intersection is the driving and passing area for vehicles and is also suitable for placing the main exhaust fan 10 or the booster exhaust fan 5.

[0031] The inner end suction opening of the exhaust duct 18 is finally located on the upper end wall of the exhaust widening area 11 at the acute-angled oblique intersection of the pilot tunnel and the main tunnel. The suction force generated by the chimney for exhaust draws out the polluted air in the pilot tunnel and the main tunnel at the inner end of the exhaust duct without power throughout the day and discharges it outside the tunnel through the chimney for exhaust, which can ensure the extraction of polluted air in the pilot tunnel and the main tunnel without power throughout the day and save a large amount of energy.

[0032] (c) An exhaust duct 12 is arranged, and a main exhaust fan 10 is installed on the middle wall of the exhaust widening area. The air inlet of the main exhaust fan faces the main tunnel face. When necessary, the main exhaust fan is started to discharge the polluted air in the guide tunnel and the main tunnel out of the tunnel through the air outlet of the main exhaust fan, the exhaust duct, and the wind extraction chimney. When necessary, the main exhaust fan 10 is started when the exhaust duct cannot effectively and quickly exhaust dust.

[0033] The clearance between the soft air duct, exhaust duct and exhaust duct and the ground should be mainly to ensure the normal passage of vehicles below.

[0034] (4) For ventilation and dust removal of the main tunnel construction that is more than 30 m away, a combination of forced-in ventilation and exhaust chimneys to generate exhaust force, exhaust from the main exhaust fan exhaust duct, and mobile dust isolation walls 3 to isolate the main tunnel face construction area 4 is adopted; (a) Assemble a movable dust-proof wall 3 in the main tunnel. The movable dust-proof wall is set 20 to 25 meters away from the main tunnel face. The movable dust-proof wall isolates the construction area of ​​the main tunnel face and is advanced synchronously with the excavation of the main tunnel face.

[0035] like Figure 3 As shown, the movable dust-proof wall 3 is provided with two door frames 311 spaced apart from each other, and the upper ends of the two door frames 311 are fixed as one with the two ends of the lower part of the upper beam frame 38. The lower ends of the two door frames are fixed as one with the middle of the upper end of a steel seesaw 31, which is made of a steel plate with a length of 6m, a width of 1m, a thickness of 2cm and both ends tilted upward. A pulling hole is provided in the middle of the tilted steel plate, which is used to pull the steel seesaw forward and backward with the help of external force. The steel seesaw is used to move and support the movable dust-proof wall.

[0036] The upper ends of the steel rocker 31 and the corresponding lower parts of the door frames 311 are provided with oblique support rods 34 to strengthen the fixed support of the door frame. A reel roller 39 is provided in the middle part of the upper beam frame. The reels in the middle parts of the two ends of the reel roller 39 are respectively connected to the motor shafts of the reel motor 310 located at the two ends of the upper beam frame. The inner sides of the two door frames on both sides of the lower end of the reel roller are provided with corresponding concave slide grooves 36 for curtain doors. The upper end of the rolling shutter door 32 is fixed to the reel roller, and the two sides of the rolling shutter door are slidably fitted in the concave slide grooves of the curtain door on the corresponding sides. The lower end of the rolling shutter door is connected to the curtain door bottom plate 33 which is slidably fitted in the concave slide grooves of the curtain door. The inflatable bag wall 313 is semicircular, and a rectangular opening groove is provided in the middle of the straight side of the inflatable bag wall. The three sides of the rectangular opening groove of the inflatable bag wall 313 are respectively connected to the outer sides of the corresponding two door frames and the upper sides of the door frames. Exhaust holes 312 for exhaust pipes to pass through and air supply holes 35 for soft air belts to pass through are respectively provided on the inflatable bag walls on both sides of the rectangular opening groove. An inflator 314 is provided at the lower ends of the two door frames, and the inflation port of the inflator is connected to the air inlet of the inflatable bag wall.

[0037] When the mobile dust partition wall isolates the construction area of the main tunnel heading face, the mobile dust partition wall is towed to a position 20 - 25 m away from the main tunnel heading face. After the inflator starts, the airbag wall is inflated. After the airbag wall expands, the space between the outer sides of the two door frames and the upper side of the door frames and the main tunnel wall 37 is sealed. The reel motor 310 starts to drive the reel roller to rotate, causing the lower end of the rolling shutter door 32 wound on it to move downward. The lowered rolling shutter door seals the space between the inner sides of the two door frames and the lower side of the door frames, forming a mobile dust partition wall to isolate the construction area of the main tunnel heading face. At this time, the dust in the construction area of the main tunnel heading face will not leak out through the mobile dust partition wall to pollute other areas in the main tunnel. The ventilation and dust extraction in the isolated construction area of the main tunnel heading face are completed by the soft air duct passing through the air supply holes of the mobile dust partition wall to press air to the pilot tunnel heading face and the exhaust duct passing through the exhaust holes of the mobile dust partition wall. When slag needs to be transported out of the construction area of the main tunnel heading face, the reel motor 310 starts to drive the reel roller to rotate in the reverse direction, causing the lower end of the rolling shutter door 32 wound on it to move upward. The retracted rolling shutter door opens the space between the inner sides of the two door frames and the lower side of the door frames, and the slag transport vehicle can enter the construction area of the main tunnel heading face from the rolling shutter door to load and transport the slag.

[0038] (b) The inner end air extraction opening of the exhaust duct is located on the upper end wall of the widened exhaust area where the pilot tunnel and the main tunnel intersect at an acute angle. The extraction chimney generates an extraction force to extract the polluted air in the pilot tunnel and the main tunnel at the inner end of the exhaust duct without power and discharges it out of the tunnel through the extraction chimney.

[0039] (c) Extend the soft air duct section V until the air outlet of the soft air duct passes through the mobile dust partition wall and communicates with the outer side in the construction area of the main tunnel heading face and advances synchronously with the excavation of the main tunnel heading face; when the mobile dust partition wall moves forward, the inflator is closed to deflate and contract the airbag wall to facilitate the forward movement of the mobile dust partition wall.

[0040] (d) As the construction heading face advances, the main exhaust fan 10 also moves forward to a position 30 m away from the main tunnel heading face. The exhaust duct is correspondingly lengthened to communicate with the air outlet of the main exhaust fan. The air inlet of the main exhaust fan communicates with the space between the mobile dust partition wall and the heading face through another section of the exhaust duct. A booster exhaust fan 5 is provided at the original position of the main exhaust fan. The air outlet of the booster exhaust fan is introduced into the return air flow of the exhaust duct. The exhaust duct is always located on the upper end wall on one side of the pilot tunnel or the main tunnel through the support frame.

[0041] Such as Figure 6 、 7As shown, the support frame 14 is used to support the exhaust duct, the exhaust duct and the soft air belt tube. The support frame is a tripod, and the tripod structure is formed by a vertical support plate 145, a horizontal support plate 142, and an inclined support plate 143. One end of the horizontal support plate is connected to the upper end of the vertical support plate, and the two ends of the inclined support plate are respectively connected to the lower end of the inner side of the horizontal support plate and the middle of the lower end of the outer side of the horizontal support plate. A reinforcing angle plate 144 is provided at the corner where the horizontal support plate and the vertical support plate intersect, which is used to strengthen the strength of the tripod. A semicircular upwardly open ring frame 141 is provided at the upper end of the horizontal support plate, and anchor rod through holes 146 are provided at the upper and lower parts of the front of the vertical support plate. When in use, the tripod is fixed to the upper part of the guide hole or the main hole wall by passing the anchor rod through the anchor rod through the anchor rod through hole, and the exhaust duct, the exhaust duct and the soft air belt tube can be located in the semicircular upwardly open ring frame 141. Several tripods are fixed to the upper part of the guide hole or the main hole wall at intervals.

[0042] like Figure 4 , 5 As shown, a motor 53 is provided in the middle of a casing 56 of the boost exhaust fan 5 through a motor bracket 54, an exhaust blade 51 is provided on the motor shaft, an air inlet 52 is provided at the front end of the casing, a closed mesh is provided on the air inlet 52 to ensure safety, an air outlet tube 58 is provided at the upper rear end of the casing or at the upper part of the side away from the palm face, an arc-shaped guide plate 55 inclined toward the air outlet is provided on the inner wall of the casing at the rear side of the motor for guiding air, a one-way valve 57 is provided on the air outlet for one-way opening of the air outlet, the air outlet is communicated with the lower part of the exhaust tube through a guide tube 20, an arc-shaped guide plate 17 is provided in the exhaust tube on the windward side of the guide tube outlet to guide the polluted air drawn in from the boost exhaust fan into the return air flow of the exhaust tube pipeline, and a one-way valve 19 is provided in the exhaust tube at the front end of each boost exhaust fan to prevent the polluted air drawn in from the boost exhaust fan from flowing in reverse.

[0043] like Figure 8 As shown, (5) an additional axial flow compressor 15 is provided at 50-55m of each extended soft air belt pipeline V segment to enhance the air supply force of the soft air belt pipe, and a booster exhaust fan is provided at 60-65m of each extended exhaust pipe pipeline to enhance the dust removal function of the facing tunnel construction area and the main tunnel. The housing 155 of the additional axial flow compressor 15 is a through cylinder, and an enhanced motor 153 and a booster blade 154 driven by its motor shaft are provided in the housing. The front port of the through cylinder is the air outlet 152, and the rear port of the through cylinder is the air inlet 151. The air outlet and air inlet of the additional axial flow compressor 15 are connected to the soft air belt pipeline to enhance the air supply function of the facing tunnel construction area and the main tunnel.

[0044] (6) Repeat steps (4) and (5) until the main hole is connected.

[0045] In summary, the present invention can ensure that when a pilot tunnel intersects with the main tunnel at an acute angle and single-heading tunneling is adopted, the polluted air in the large-area main tunnel can be effectively discharged from the small-area pilot tunnel, which further guarantees the construction environment in the main tunnel, improves the construction efficiency, and has the advantages of high construction efficiency, low comprehensive cost, and remarkable purification effect.

[0046] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A construction method for single - head tunneling with reverse ventilation when the pilot tunnel intersects the main tunnel obliquely at an acute angle, characterized in that , including the following steps: (1) Set up a chimney for exhaust air on one side near the access tunnel opening. The height of the chimney for exhaust air is greater than 30 m. There is an air inlet on each side corresponding to the bottom of the chimney for exhaust air. One end of the exhaust air duct is connected to one of the air inlets of the chimney for exhaust air, and the other end of the exhaust air duct follows the upper end wall on the side away from the acute-angled hypotenuse of the access tunnel to a position 15 m away from the tunnel face of the access tunnel and synchronously advances as the tunnel face of the access tunnel is under construction; One end of the exhaust air pipe is connected to the other air inlet of the chimney for exhaust air, and the other end of the exhaust air pipe is hung along the lower part of the exhaust air duct on the upper end wall on the side away from the acute-angled hypotenuse of the access tunnel and communicates with the air outlet of the main exhaust fan in the access tunnel or the main tunnel; (2) Ventilation and dust removal in the construction section of the access tunnel: Adopt a combined method of forced ventilation and suction by the chimney for exhaust air in the construction section of the access tunnel; (a) Within 25 m of the excavation of the access tunnel, set up a compressor outside the access tunnel opening. During the construction of the access tunnel, use an axial flow compressor to connect a 1.5 m diameter flexible air duct section I to supply air pressure to the tunnel face of the access tunnel, and the polluted air is discharged outside the tunnel through the construction access tunnel; (b) When the excavation of the access tunnel is more than 25 m, set up a compressor outside the tunnel opening. During the construction of the access tunnel, use an axial flow compressor to connect a 1.5 m diameter flexible air duct section I to supply air pressure to the tunnel face of the access tunnel, and the polluted air is discharged outside the tunnel through the construction access tunnel. The flexible air duct section I is hung along the upper part inside the acute-angled hypotenuse of the access tunnel through a support frame; The inner end of the exhaust air duct is hung along the upper part outside the acute-angled hypotenuse of the access tunnel opening to a position 15 m away from the tunnel face of the access tunnel and synchronously advances as the tunnel face is under construction. The chimney for exhaust air generates a suction force to extract the polluted air at one end of the exhaust air duct from the access tunnel without power; (3) Ventilation and dust removal during the construction within 30 m of the access tunnel entering the main tunnel. Adopt a combined method of forced ventilation, suction by the chimney for exhaust air, and exhaust by the exhaust air pipe of the main exhaust fan; (a) Layout of the flexible air duct. Set up a compressor at the access tunnel opening to supply air pressure into the tunnel. Use an axial flow compressor to connect a 1.5 m diameter flexible air duct to supply air pressure to the tunnel face of the access tunnel. The flexible air duct is longitudinally laid in sections as the excavation tunnel face advances. Hang the flexible air duct section I along the upper part inside the acute-angled hypotenuse of the access tunnel opening. After the flexible air duct enters the main tunnel, hang the flexible air duct section II along the upper part inside the main tunnel by continuously correcting in the direction of excavation of the main tunnel. Then, successively correct and hang the flexible air duct sections III and IV in the direction of excavation of the main tunnel until the flexible air duct section V is hung when the direction of the flexible air duct is corrected to meet the ventilation requirements of the main tunnel; (b) Layout of the exhaust air duct. Set up an exhaust air widened area at the acute-angled oblique intersection of the access tunnel and the main tunnel. The inner end air suction port of the exhaust air duct is finally located on the upper end wall of the exhaust air widened area at the acute-angled oblique intersection of the access tunnel and the main tunnel. The chimney for exhaust air generates a suction force to extract the polluted air in the access tunnel and the main tunnel at the inner end of the exhaust air duct without power and discharges it outside the tunnel through the chimney for exhaust air; (c) Layout of the exhaust air pipe. Set up a main exhaust fan on the middle wall of the exhaust air widened area. The air inlet of the main exhaust fan faces the tunnel face of the main tunnel. When necessary, the main exhaust fan starts to discharge the polluted air in the access tunnel and the main tunnel through the air outlet of the main exhaust fan, the exhaust air pipe, and the chimney for exhaust air outside the tunnel; (4) For ventilation and dust removal in tunnel construction more than 30 m away, a combination of forced-in ventilation and exhaust chimneys to generate exhaust force, exhaust from the main exhaust fan exhaust duct, and mobile dust isolation walls to isolate the face construction area is adopted; (a) Assemble a mobile dust-proof wall in the main tunnel. The mobile dust-proof wall is set 20 to 25 meters away from the main tunnel face. The mobile dust-proof wall isolates the main tunnel face construction area and is advanced synchronously with the excavation of the main tunnel face; (b) The exhaust port at the inner end of the exhaust duct is ultimately located on the upper end wall of the exhaust widening area at the acute angle intersection of the pilot tunnel and the main tunnel. The exhaust chimney generates exhaust force to unpoweredly extract the polluted air in the pilot tunnel and the main tunnel at the inner end of the exhaust duct and discharge it out of the tunnel through the exhaust chimney; (c) Extend the soft air belt pipeline V segment to the soft air belt outlet, pass through the movable dust isolation wall to the outer edge of the main tunnel face construction area, and advance synchronously with the excavation of the main tunnel face; (d) As the construction face advances, the main exhaust fan moves forward to a position 30m away from the main tunnel face. The exhaust duct pipeline is correspondingly extended to connect to the main exhaust fan outlet. The main exhaust fan inlet is connected to the space between the movable dust-proof wall and the face through another section of exhaust duct. A booster exhaust fan is installed at the original position of the main exhaust fan. The outlet of the booster exhaust fan is introduced into the return air flow of the exhaust duct pipeline. The exhaust duct pipeline is always located on the upper end wall on the side away from the pilot tunnel or the main tunnel through the support frame; (5) An additional axial flow compressor fan is installed at 50-55m of each extended soft air belt pipeline V section to enhance the air supply force of the soft air belt pipe, and a booster exhaust fan is installed at 60-65m of each extended exhaust pipe pipeline to enhance the dust removal function of the tunnel face construction area and the main tunnel; (6) Repeat steps (4) and (5) until the main hole is connected.

2. The method according to claim 1, wherein: The air compressor is located 5 to 8 meters away from the guide tunnel opening to ensure that the air pressure into the guide tunnel will not be affected by the exhaust air.

3. The method according to claim 1, characterized in that: The movable dust-proof wall is a pair of door frames arranged at a distance from each other on the left and right sides, the upper ends of the two door frames are respectively fixed to the two ends of the lower part of the upper beam frame as a whole, the lower ends of the two door frames are respectively fixed to the middle part of the upper end of a steel seesaw as a whole, the two ends of the upper part of the steel seesaw and the corresponding lower part of the door frame are provided with oblique support rods, a reel roller is provided in the middle part of the upper beam frame, the reels in the middle of the two ends of the reel roller are respectively connected to the motor shaft of the reel motor located at the two ends of the upper beam frame, the inner sides of the two door frames on both sides of the lower end of the reel roller are correspondingly provided with concave sliding grooves for curtain doors, and the upper end of the rolling door is fixed to the reel roller. The two sides of the rolling shutter door are slidably fitted in the concave sliding grooves of the curtain door on the corresponding sides, the lower end of the rolling shutter door is connected to the curtain door bottom plate which is slidably fitted in the concave sliding grooves of the curtain door, the inflatable bag wall is semicircular, and a rectangular opening groove is provided in the middle of the straight side of the inflatable bag wall, and the three sides of the rectangular opening groove of the inflatable bag wall are respectively connected to the outer sides of the two corresponding door frames and the upper sides of the door frames, and exhaust holes for exhaust pipes to pass through and air supply holes for soft air belts to pass through are respectively provided on the inflatable bag walls on both sides of the rectangular opening groove, and an inflator is provided at the lower ends of the two door frames, and the inflation port of the inflator is communicated with the air inlet of the inflatable bag wall.

4. The method according to claim 1, wherein: The diameter of the wind extraction chimney is 1.6-2m, and it stands vertically and fixedly according to the mountain terrain.

5. The method according to claim 1, characterized in that: The exhaust duct is a 1m-diameter iron sheet duct or plastic synthetic material duct, and the exhaust air duct is a 1.2m-diameter iron sheet duct or plastic synthetic material duct.

6. The method according to claim 1, wherein: In the middle of the casing of the booster exhaust fan, there is a motor provided through a motor bracket. An exhaust air blade is provided on the motor shaft. An air inlet is provided at the front end of the casing. An air outlet cylinder is provided at the upper part of the rear of the casing or on the upper part of the side away from the heading face. An arc-shaped flow guide plate inclined towards the air outlet is provided on the inner wall of the casing at the rear side of the motor. A one-way valve is provided at the air outlet. The air outlet communicates with the inside of the lower part of the exhaust air duct through a guide tube. An arc-shaped air guide plate is provided in the exhaust air duct on the windward side of the air outlet of the guide tube. A one-way valve is provided in the exhaust air duct at the front end of each booster exhaust fan.

7. The method according to claim 1, characterized in that: The support frame is a triangular frame, and the triangular frame is fixed to the pilot tunnel or the main tunnel wall through anchor bolts. A semi-circular upward-opening ring frame is provided at the upper end of the triangular frame.

8. The method according to claim 1, characterized in that: When the flexible air duct enters the main tunnel from the pilot tunnel, there is a high difference point. The flexible air duct crossing the high difference point is a straight section to ensure sufficient air pressure supply.

9. The method according to claim 1, wherein: The correction angle of the flexible air duct from section I to section II should maintain a large obtuse angle so that section II of the flexible air duct has a longer usable length.

10. The method according to claim 1, characterized in that: The clearances of the flexible air duct, exhaust duct and exhaust air duct from the ground are mainly to ensure the normal passage of vehicles below.

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