Ventilation method for tunnel construction in plateau region

Abstract

The application discloses a tunnel construction ventilation method in a plateau area, comprising the following steps: S1, in the horizontal hole construction stage, a first fan assembly is arranged at the horizontal hole opening, air is supplied to the working face of the horizontal hole and the horizontal hole branch hole through the first air pipe assembly by using the pressure-in ventilation mode until the construction of the horizontal hole and the horizontal hole branch hole are completed; S2, a second fan assembly is arranged at the horizontal hole branch hole opening, air is supplied to the working face of the left line of the main hole and the right line of the main hole through the second air pipe assembly by using the pressure-in ventilation mode; and S3, a third fan assembly is arranged at a position close to the second auxiliary hole in the right line of the main hole, air is supplied to the working face of the left line of the main hole and the right line of the main hole by using the roadway ventilation mode. Based on the construction characteristics of the tunnel, the construction ventilation system and the ventilation method are optimized according to different construction stages, so that the problem that the ventilation effect in the tunnel is difficult to guarantee in the tunnel construction in the plateau area can be solved well.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology, specifically relating to a ventilation method for tunnel construction in plateau areas. Background Technology

[0002] With the vigorous development of domestic infrastructure construction, railway transportation infrastructure has gradually expanded from plains to mountainous and plateau regions, resulting in an increasing number and length of tunnels. This has brought significant challenges to tunnel construction. Furthermore, the thin air, low air pressure, cold temperatures, and lack of oxygen in plateau environments also pose considerable difficulties for the construction of long-distance tunnels. In order to improve tunnel construction efficiency, the number and power of large-scale engineering machinery used in tunnel construction are increasing. Combined with the oxygen-deficient environment of plateaus, this leads to poor air circulation within the tunnels, harsh working conditions, and insufficient oxygen supply. This can easily cause oxygen deficiency among construction workers, incomplete combustion of fuel in engineering machinery, and low efficiency for both personnel and machinery. Therefore, high requirements are placed on ventilation within tunnels during construction in plateau environments. Summary of the Invention

[0003] The purpose of this invention is to provide a ventilation method for tunnel construction in plateau areas, so as to solve the problem of difficult tunnel ventilation in long-distance tunnel construction in plateau areas.

[0004] This invention is achieved through the following technical solution:

[0005] Ventilation methods for tunnel construction in plateau areas: The construction method adopted in tunnel construction is to first construct a cross tunnel and then construct a main tunnel connected to the cross tunnel. The main tunnel includes a parallel left line and a right line, wherein the cross tunnel is connected to the left line of the main tunnel.

[0006] The ventilation methods for tunnel construction include the following steps:

[0007] S1. During the construction phase of the transverse tunnel, the first fan assembly is installed at the entrance of the transverse tunnel. The forced ventilation method is used to send air to the working face of the transverse tunnel and the transverse tunnel branch through the first air duct assembly until the construction of the transverse tunnel and the transverse tunnel branch are completed.

[0008] S2. After the cross tunnel construction is completed, the main tunnel will be constructed. In the first stage of the main tunnel construction, the small mileage section of the main tunnel will be constructed until the small mileage section of the main tunnel is connected. The first auxiliary tunnel connecting the left line and the right line of the main tunnel will be constructed between the left line and the right line of the main tunnel.

[0009] The ventilation method at this stage is as follows: a second fan assembly is installed at the entrance of the transverse branch tunnel, and forced ventilation is used to send air to the working faces of the left and right lines of the main tunnel through the second duct assembly.

[0010] After the small-mileage section of the main tunnel is completed, the construction of the large-mileage section of the main tunnel will continue in the second stage of the main tunnel construction. After the large-mileage section of the main tunnel is constructed to the set position, the second auxiliary tunnel connecting the left line and the right line of the main tunnel will be constructed between the left line and the right line of the main tunnel.

[0011] The ventilation method for this stage is as follows: a third fan assembly is installed in the right line of the main tunnel near the second auxiliary tunnel, and air is supplied to the working faces of the left and right lines of the main tunnel using a tunnel ventilation method.

[0012] As a further improvement to the above technical solution, in step S1, the first fan assembly uses one fan for ventilation operation. When construction is required on the cross tunnel and the cross tunnel branch tunnel at the construction position, the two working faces are alternately constructed, and the air valves set on the first air duct assembly are controlled to alternately supply air to the corresponding working face.

[0013] As a further improvement to the above technical solution, in step S2, one fan in the second fan assembly is used to supply air to the small mileage side of the left and right lines of the main tunnel. When constructing the small mileage section of the left and right lines of the main tunnel, the working faces of the left and right lines of the main tunnel are constructed alternately, and the air valves set on the second air duct assembly are controlled to alternately supply air to the corresponding working faces.

[0014] As a further improvement to the above technical solution, in step S2, when constructing the large mileage sections of the left and right lines of the main tunnel during this construction phase, the other two fans in the second fan assembly are used to supply air to the working faces corresponding to the large mileage sides of the left and right lines of the main tunnel.

[0015] As a further improvement to the above technical solution, in step S3, during this construction stage, two fans are used to supply air to the working face on the large mileage side of the left and right lines of the main tunnel, respectively.

[0016] As a further improvement to the above technical solution, in step S3, a wind-blocking structure is installed at the location of the second auxiliary tunnel inside the right line of the main tunnel. The wind-blocking structure is used to block the return air from the working face of the right line of the main tunnel, so that it flows back along the left side of the main tunnel through the second auxiliary tunnel.

[0017] As a further improvement to the above technical solution, in steps S1, S2 and S3, the return air velocity at the working face is not less than 0.3m / s when air is supplied to the working face.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] Based on the construction characteristics of tunnels, this invention optimizes the construction ventilation system and ventilation methods according to different construction stages. This effectively solves the problem of ensuring ventilation effect inside tunnels during construction in plateau areas. Furthermore, the overall structure of the ventilation system is simple, and the efficiency of the fans in the ventilation system is optimized. While ensuring ventilation effect, it can reduce the layout and number of fans and ducts, reduce the workload of ventilation system construction in plateau areas, and reduce the occupation of space inside the tunnel. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a structural layout diagram of the ventilation system during the tunnel cross-section construction stage in the ventilation method of the present invention.

[0022] Figure 2 This is a structural layout diagram of the ventilation system during the small-mileage construction stage of the main tunnel in the ventilation method of the present invention.

[0023] Figure 3 This is a structural layout diagram of the ventilation system during the large-mileage construction phase of the main tunnel in the ventilation method of the present invention.

[0024] in:

[0025] 10. Horizontal tunnel; 11. Horizontal tunnel branch tunnel; 21. Main tunnel left line short mileage section; 22. Main tunnel right line short mileage section; 23. Main tunnel left line long mileage section; 24. Main tunnel right line long mileage section; 25. First auxiliary tunnel; 26. Second auxiliary tunnel; 31. First fan assembly; 32. Second fan assembly; 33. Third fan assembly; 41. First air duct; 42. First air duct branch pipe; 43. Second short mileage main air duct; 44. Second short mileage branch air duct; 45. Second long mileage left line air duct; 46. Second long mileage right line air duct; 47. Third long mileage left line air duct; 48. Third long mileage right line air duct; 50. Wind-blocking structural components. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0027] During tunnel construction, ventilation methods typically include: forced ventilation, which has good ventilation effect but is prone to polluting the entire tunnel environment; exhaust ventilation, which requires a small air volume and does not pollute the environment, but the ventilation time is long; mixed ventilation, which has the advantages of both, but due to the increase in equipment and pipelines, it is limited by the tunnel clearance size, affecting construction operations; and tunnel ventilation and duct ventilation, which are suitable for long tunnels with single-heading excavation, supplemented by auxiliary channels such as horizontal pilot shafts, inclined shafts, and vertical shafts to form local ventilation circulation, shorten the tunnel ventilation distance, and improve ventilation efficiency.

[0028] The tunnel construction project is located in a high-altitude region, above 3000 meters, with a long tunnel length, harsh construction conditions, and high construction difficulty. Considering the geographical environment, the tunnel construction method adopted was to first construct the cross passages and then construct the main tunnel connecting to them. (Refer to...) Figure 1 The main tunnel includes a parallel left main tunnel line and a right main tunnel line, with the transverse tunnel connected to the left main tunnel line.

[0029] In this embodiment, the tunnel construction ventilation method supplies fresh air to the tunnel interior during construction and removes polluted gases, ensuring the working needs of construction personnel and machinery. The specific ventilation method employed, tailored to the chosen tunnel construction method, includes the following steps:

[0030] S1. During the construction phase of the transverse tunnel, refer to... Figure 1 Using the first fan assembly 31 installed at the entrance of the transverse tunnel 10, air is supplied to the construction face of the transverse tunnel and the transverse tunnel branch tunnel in a forced ventilation manner until the construction of the transverse tunnel and the connection of the transverse tunnel branch tunnel are completed. During this construction stage, when construction is carried out at the construction position of the transverse tunnel branch tunnel, the construction method of alternating construction of the transverse tunnel face and the transverse tunnel branch tunnel face is adopted. At this time, the air valve on the first air duct assembly is controlled to alternately supply air to the corresponding construction face.

[0031] S2. After completing the construction of the transverse tunnel, proceed with the construction of the main tunnel, referring to... Figure 2 In this step, the construction of the small-mileage section of the main tunnel is carried out until the small-mileage section of the main tunnel is completed. The first auxiliary tunnel connecting the left and right lines of the main tunnel is constructed between the left and right lines of the main tunnel. In this step, the second fan assembly 32 set at the entrance of the transverse branch tunnel supplies air to the working faces of the left and right lines of the main tunnel respectively in a forced ventilation direction. In this step, one fan supplies air to the small-mileage side of the left and right lines of the main tunnel. When constructing the small-mileage section of the left and right lines of the main tunnel, the working faces of the left and right lines of the main tunnel are constructed alternately, and the air valves set on the second air duct assembly are controlled to alternately supply air to the corresponding working faces.

[0032] In this step, when constructing the long-mileage sections of the left and right tunnels, other fans can be used to supply air to the working faces on the long-mileage side of the left and right tunnels respectively.

[0033] S3. After the main tunnel is completed at a short mileage section, refer to Figure 3 In this step, construction continues on the main tunnel section. After the main tunnel section is constructed to a certain distance from the cross tunnel, a second auxiliary tunnel connecting the left and right lines of the main tunnel is constructed between the left and right lines of the main tunnel.

[0034] In this step, the third fan assembly 33, located near the second auxiliary tunnel in the right line of the main tunnel, supplies air to the working faces of the left and right lines of the main tunnel respectively using a tunnel ventilation method; in this step, two fans are used to supply air to the working faces of the left and right lines of the main tunnel respectively on the larger mileage side.

[0035] During this stage of construction, depending on the length of the main tunnel section, it may be necessary to construct a third or fourth auxiliary tunnel after a certain distance has been reached. Accordingly, the third fan unit will be moved to the location of the third or fourth auxiliary tunnel to supply air to the corresponding working face, and corresponding wind-blocking structural components will be set at the corresponding locations to form a predetermined gas return channel. These are all conventional improvements that can be made based on the above embodiments.

[0036] During the ventilation operation described above, when air is supplied to the tunnel face, the return air velocity at the tunnel face should not be less than 0.3 m / s to meet the requirements of tunnel construction and ventilation efficiency.

[0037] In this embodiment, the ventilation system used based on the above-mentioned ventilation method is mainly used for ventilation throughout the entire construction process of the transverse tunnel and the main tunnel. Based on the ventilation requirements of different construction stages, the construction stages are divided into the transverse tunnel construction stage, the main tunnel short-mileage construction stage, and the main tunnel long-mileage construction stage. The transverse tunnel construction stage refers to the stage where the transverse tunnel is constructed up to the left line position of the main tunnel. The main tunnel short-mileage construction stage refers to the stage where the main tunnel short-mileage section is constructed until it is completed. The main tunnel long-mileage construction stage refers to the stage where, after the completion of the short-mileage section, the main tunnel long-mileage section is constructed until it is completed.

[0038] To address the different construction stages and their ventilation needs and characteristics throughout the entire construction process, the ventilation system includes a cross tunnel construction ventilation system, a main tunnel short-mileage construction ventilation system, and a main tunnel long-mileage construction ventilation system.

[0039] During the construction phase of the transverse tunnel, the ventilation system primarily provides ventilation inside the tunnel during the construction process. (Refer to...) Figure 1 The ventilation system for the horizontal tunnel construction includes:

[0040] The first fan assembly 31 is installed at the entrance of the transverse tunnel 10 during construction;

[0041] A transverse branch tunnel 11, which connects to the transverse tunnel, is located near the left line of the main tunnel.

[0042] The first fan assembly 31 is connected to the first duct assembly, and air is delivered to the working face of the transverse tunnel and the transverse tunnel branch through the first duct assembly.

[0043] Here, the first fan assembly 31 uses an axial flow fan (TV(H)-2*14#90kW, H1-3). The first duct assembly includes a first duct 41 extending along the working face of the transverse tunnel along the axis of the transverse tunnel and a first duct branch 42 connecting the first duct. The first duct branch 42 extends along the axis of the transverse tunnel branch towards the working face of the transverse tunnel branch. The first duct and the first duct branch are low-leakage ducts with a diameter of 1.6m. The first duct is connected to the axial flow fan and uses a forced ventilation method to supply air to the working face of the transverse tunnel and the transverse tunnel branch.

[0044] During the construction phase of the transverse tunnel, the auxiliary tunnels have already been completed. During the short-mileage construction phase of the main tunnel, the ventilation system primarily serves the internal ventilation of this short-mileage section of the main tunnel. (Refer to...) Figure 2 The ventilation system for the main tunnel's short-mileage construction includes:

[0045] The second fan assembly 32 is installed at the entrance of the transverse branch tunnel;

[0046] At the location corresponding to the transverse tunnel 10, a first auxiliary tunnel 25 is set up to connect the left line of the main tunnel and the right line of the main tunnel;

[0047] The second fan assembly 32 is connected to the second duct assembly. The second duct assembly 32 extends through the first auxiliary hole 25 to the left line and right line of the main tunnel, and supplies air to the working face of the left line and right line of the main tunnel through the second duct assembly.

[0048] Here, the second fan assembly 32 uses three axial flow fans. At this time, the axial flow fan (H1-3) originally set at the entrance of the horizontal tunnel can be moved to the position of the horizontal tunnel branch. At this time, it is only necessary to add two more axial flow fans (H1-1 and H1-2 respectively, model TV(H)-2*14#110kW).

[0049] The second duct assembly 32 here includes a second minor mileage main duct 43, a second major mileage left-line duct 45, and a second major mileage right-line duct 46. The second minor mileage main duct 43 extends along the first auxiliary tunnel 25 to the right line of the main tunnel. Two second minor mileage branch ducts 44 are installed on the second minor mileage main duct 43 facing the minor mileage direction of the main tunnel. The two second minor mileage branch ducts 44 are respectively installed along the axial direction of the left line and the right line of the main tunnel and extend to the corresponding working face positions. The second minor mileage main duct is connected to an axial flow fan (H1-3) and uses a forced ventilation method to supply air to the working faces of the minor mileage section 21 of the left line and the minor mileage section 22 of the right line of the main tunnel. The second minor mileage main duct and the second minor mileage branch ducts are both low-leakage ducts with a diameter of 1.6m.

[0050] The second major mileage left-line ventilation duct 45 extends towards the main tunnel major mileage construction direction and is installed at the working face of the main tunnel major mileage. The second major mileage left-line ventilation duct is connected to an axial flow fan (H1-1) and uses a forced ventilation method to supply air to the working face of the main tunnel major mileage. The second major mileage left-line ventilation duct is a low-leakage duct with a diameter of 1.8m.

[0051] The second major mileage right-line ventilation duct 46 extends from the first auxiliary tunnel towards the vibratory mileage construction direction to the working face of the main tunnel's right-line major mileage. The second major mileage right-line ventilation duct is connected to axial flow fans (H1-2) and uses a forced ventilation method to supply air to the working face of the main tunnel's right-line major mileage. The second major mileage right-line ventilation duct is a low-leakage duct with a diameter of 1.8m.

[0052] After the main tunnel is completed at its shortest mileage, during the construction phase at the longest mileage, the ventilation system at this stage primarily provides ventilation for the interior of that section of the main tunnel. (Refer to...) Figure 3 The main tunnel's large-scale ventilation system includes:

[0053] A second auxiliary tunnel 26 is set up at an interval from the first auxiliary tunnel, facing the construction direction of the main tunnel at a large mileage. The second auxiliary tunnel 26 connects the large mileage section 23 of the left line of the main tunnel and the large mileage section 24 of the right line of the main tunnel.

[0054] The third fan assembly 33 is located inside the right line of the main tunnel, near the second auxiliary tunnel.

[0055] The third fan assembly 33 is connected to the third duct assembly, and air is delivered to the working faces of the left and right tunnels of the main tunnel through the third duct assembly.

[0056] Here, the third fan assembly 33 uses two axial flow fans. At this time, the two axial flow fans (H1-1, H1-2) originally installed at the entrance of the transverse branch tunnel can be moved to the right line of the main tunnel.

[0057] The third duct assembly here includes the left-line duct 47 and the right-line duct 48 of the third major mileage. The left-line duct 47 extends from the second auxiliary tunnel towards the working face of the main tunnel at the major mileage, and is connected to an axial flow fan (H1-1) to supply air to the working face of the main tunnel at the major mileage. The right-line duct 48 extends towards the working face of the main tunnel at the major mileage, and is connected to an axial flow fan (H1-2) to supply air to the working face of the main tunnel at the major mileage. Both the left-line and right-line ducts of the third major mileage are low-leakage ducts with a diameter of 1.8m.

[0058] Reference Figure 3 A wind-blocking structure 50 is installed inside the right line of the main tunnel at the location of the second auxiliary tunnel. The wind-blocking structure 50 is used to block the return air from the working face of the right line of the main tunnel, so that the return air on this side flows back along the left side of the main tunnel after passing through the second auxiliary tunnel.

[0059] Of course, the formulation of ventilation plans during tunnel construction needs to consider factors such as tunnel length, tunnel chamber layout and number, topographic features at tunnel chamber entrances and exits, and on-site construction conditions. Here, considering the tunnel's characteristics and the construction methods employed, different ventilation methods are used at different construction stages. Furthermore, the selection of ventilation methods at each stage is tailored to the high-altitude environment and actual construction conditions. While ensuring ventilation effectiveness at each stage, the complexity of the ventilation system is minimized, making the fan system layout simpler and reducing the space occupied by the ventilation system in the tunnel construction area. Specifically, in this construction project, in addition to the high-altitude environment, the remote construction location, inconvenient transportation, and small available working area pose significant challenges to the ventilation system setup. To address these issues, the ventilation system and methods at each stage are optimized. Taking into account the actual construction terrain characteristics, ventilation is achieved through the use of cross passages and branch tunnels, which greatly optimizes the overall ventilation system and its effectiveness.

[0060] Considering the environmental characteristics of plateau regions, the actual ventilation effect that the ventilation method can achieve should also be taken into account, including fan power, duct diameter, etc. Corresponding influencing factors include ventilation length, construction end face size, required air volume and air pressure, etc.

[0061] Ventilation fans are classified into two types according to their energy acquisition method: axial flow fans and centrifugal fans. Axial flow fans are mostly used for tunnel ventilation. The diameter of the duct should be determined comprehensively based on the construction cross-section, ventilation volume, and duct length. Generally, large-diameter ducts are selected for long-distance air supply.

[0062] Given the environmental characteristics of plateau regions, atmospheric pressure and oxygen content are typically only about 70%-80% of those in plains areas. Therefore, certain adjustments are usually required when designing actual ventilation systems.

[0063] The air supply volume of the fan in the ventilation system is a factor that needs to be considered. The required air volume for ventilation in tunnel construction is calculated based on the maximum number of people working simultaneously in the tunnel, the minimum allowable wind speed in the tunnel, the air volume required for smoke exhaust from a single blast, and the total power of the engineering machinery and equipment. The maximum value is taken as the control air volume, and finally corrected according to atmospheric pressure.

[0064] The required air volume is calculated based on the maximum number of people working simultaneously inside the tunnel (100 people).

[0065]

[0066] K r —Heavy weight elevation correction coefficient

[0067]

[0068]

[0069] Based on the minimum allowable return air velocity inside the tunnel (0.3–0.4 m / s), the required air volume is:

[0070] Q 高 =A·v

[0071] Zhengdong Working Face: Q 高 =91.75×0.3×60=1651.50m 3 / min

[0072] Based on the calculation of the amount of internal combustion engine exhaust gas to be diluted and discharged (assuming a power of 1248kW for construction machinery equipment), the required air volume is:

[0073] Q = 4N;

[0074] Q 高 =760 / P 高 ×Q;

[0075] The efficiency of engineering machinery and equipment is assumed to be 80%, while the working coefficient is assumed to be 40%.

[0076] Q m =4N×50%=4×1248×80%×40%=1597.44m 3 / min

[0077] Q m高 =760 / 478.8×1597.44=2535.62m 3 / min

[0078]

[0079]

[0080] The required air volume for a single blast smoke extraction is:

[0081]

[0082]

[0083] In the formula:

[0084] Φ—Water leakage coefficient, taken as 0.8 for tunnels excavated along dry rock strata;

[0085] b—the amount of harmful gases generated during the explosion of the explosive; for blasting in rock strata, b = 40.

[0086] K—Diffusion coefficient 0.4;

[0087] L 临 —The tunnel length (m) required to dilute the blasting fumes to the permissible concentration;

[0088] P—Air leakage coefficient of the ventilation duct.

[0089] Maximum amount of explosives used in a single blast:

[0090] The maximum weight of the main tunnel is 119.275 kg.

[0091] The planned smoke extraction time after the blast is t = 15 minutes.

[0092]

[0093]

[0094]

[0095]

[0096]

[0097] Based on the above calculations, the required air volume for construction at the main tunnel working face can be determined, as shown in the table below:

[0098]

[0099] Calculate the fan's operating pressure and power based on the required air volume:

[0100] Fan air supply volume:

[0101] Q m =PQ

[0102]

[0103] Q m =PQ=2540.77m 3 / min;

[0104] Wind pressure:

[0105] H t ≥h f +h x ;

[0106] h f h x —These are friction loss along the friction line and local friction loss, respectively;

[0107] in,

[0108] In the formula, λ is the coefficient of friction; ρ is the air density (kg / m³). 3 ); d—duct diameter (m); β—average air leakage rate per 100 meters of duct; L—duct length (m); Q0—air volume at the end of the duct (m³ / s) 3 / s);

[0109]

[0110]

[0111] Considering that bends in the ductwork during ventilation can increase local pressure loss, a 5% safety margin for air pressure is added.

[0112] H t ≥h f +h x =(3565.27+70.20)×1.05=3817.24Pa.

[0113] The type and configuration of the fan used in each stage can be determined by calculating the working pressure and power of the fan.

[0114] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this invention is usually placed in during use. They are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0115] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this invention does not imply that the components are required to be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0116] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0117] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A ventilation method for tunnel construction in plateau areas, characterized in that, The construction method used in the tunnel construction is to first construct the cross tunnel and then construct the main tunnel that connects to the cross tunnel. The main tunnel includes a parallel left line and a right line, wherein the cross tunnel is connected to the left line of the main tunnel. The ventilation methods for tunnel construction include the following steps: S1. During the construction phase of the transverse tunnel, the first fan assembly is installed at the entrance of the transverse tunnel. The forced ventilation method is used to send air to the working face of the transverse tunnel and the transverse tunnel branch through the first air duct assembly until the construction of the transverse tunnel and the transverse tunnel branch are completed. S2. After the cross tunnel construction is completed, the main tunnel will be constructed. In the first stage of the main tunnel construction, the small mileage section of the main tunnel will be constructed until the small mileage section of the main tunnel is connected. The first auxiliary tunnel connecting the left line and the right line of the main tunnel will be constructed between the left line and the right line of the main tunnel. The ventilation method at this stage is as follows: a second fan assembly is installed at the entrance of the transverse branch tunnel, and forced ventilation is used to send air to the working faces of the left and right lines of the main tunnel through the second duct assembly. After the small-mileage section of the main tunnel is completed, the construction of the large-mileage section of the main tunnel will continue in the second stage of the main tunnel construction. After the large-mileage section of the main tunnel is constructed to the set position, the second auxiliary tunnel connecting the left line and the right line of the main tunnel will be constructed between the left line and the right line of the main tunnel. The ventilation method for this stage is as follows: a third fan assembly is installed in the right line of the main tunnel near the second auxiliary tunnel, and air is supplied to the working faces of the left and right lines of the main tunnel using a tunnel ventilation method.

2. The ventilation method for tunnel construction in plateau areas according to claim 1, characterized in that, In step S1, the first fan assembly uses one fan for ventilation. When construction is required at the cross tunnel and cross tunnel branch construction location, the two working faces are alternately constructed, and the air valves set on the first air duct assembly are controlled to alternately supply air to the corresponding working face.

3. The ventilation method for tunnel construction in plateau areas according to claim 1, characterized in that, In step S2, one fan in the second fan assembly is used to supply air to the lower mileage side of the left and right tunnels. When constructing the lower mileage section of the left and right tunnels, the working faces of the left and right tunnels are constructed alternately, and the air valves set on the second duct assembly are controlled to alternately supply air to the corresponding working faces.

4. The ventilation method for tunnel construction in plateau areas according to claim 3, characterized in that, In step S2, when the construction of the left and right tunnels of the main tunnel is carried out in this construction stage, the other two fans in the second fan assembly are used to supply air to the working face of the left and right tunnels of the main tunnels on the corresponding long mileage side.

5. The ventilation method for tunnel construction in plateau areas according to claim 1, characterized in that, In step S3, during this construction phase, two fans are used to supply air to the working face on the high-mileage side of the left and right tunnels, respectively.

6. The ventilation method for tunnel construction in plateau areas according to claim 1, characterized in that, In step S3, a wind-blocking structure is installed inside the right line of the main tunnel at the location of the second auxiliary tunnel. The wind-blocking structure is used to block the return air from the working face of the right line of the main tunnel, so that it flows back along the left side of the main tunnel through the second auxiliary tunnel.

7. The ventilation method for tunnel construction in plateau areas according to claim 1, characterized in that, In steps S1, S2, and S3, the return air velocity at the working face when air is supplied to the working face shall not be less than 0.3 m / s.

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