High-altitude long-distance tunnel construction air bin type ventilation system and construction method

Abstract

The invention discloses a high-altitude long-distance tunnel construction wind bin type ventilation system and a construction method, and relates to the technical field of high-altitude tunnel construction, the high-altitude long-distance tunnel construction wind bin type ventilation system comprises a transverse hole and a main hole, the main hole is a construction tunnel face, the transverse hole is a construction auxiliary hole, and the transverse hole and the main hole are arranged in an intersection mode; the air bin is composed of a full-section transverse tunnel, and the main tunnel and the air bin are arranged in a vertical intersection mode; the main fan is fixed at the inlet of the transverse hole; the air feeder is located in the air bin and used for supplying air to the main tunnel. The air pipe comprises an air inlet pipe and an air supply pipe; and a gas concentration monitoring member and an air return branch hole. According to the method, the altitude correction coefficient optimization calculation is added when each parameter is calculated, and the ventilation distance can be effectively prolonged, the ventilation efficiency can be improved and the ventilation problem of the high-altitude long-distance tunnel can be solved through the airflow distribution and pressurization effects of the wind bin.

Description

Technical Field

[0001] This invention relates to the field of high-altitude tunnel construction technology, specifically to a wind tunnel ventilation system and construction method for high-altitude long-distance tunnel construction. Background Technology

[0002] High-altitude, long-distance tunnel construction faces unique natural environment and engineering challenges. The high altitude, low atmospheric pressure, and thin air make traditional ventilation methods insufficient to meet the high air volume demands of parallel excavation across multiple working faces. Furthermore, the long single-ended tunnel length, numerous adits and cross passages, and concentrated construction machinery and personnel create a high risk of toxic and harmful gas accumulation and severe dust pollution, directly threatening the health of construction workers and the safety of the project.

[0003] In existing tunnel construction, arched diaphragm-type ventilation chambers are commonly used. The design of the arched diaphragm may lead to poor sealing between the ventilation chamber and the tunnel section, which can easily cause airflow short circuits or air leaks, affecting the ventilation effect. As a result, during tunnel construction, due to poor sealing, harmful gases (such as carbon monoxide and dust) may not be effectively discharged, increasing construction risks. In addition, if the diaphragm of the arched diaphragm-type ventilation chamber is not set properly, it is easy to generate eddies, which can cause severe wear and tear on the ventilation ducts during use, resulting in a short service life. Summary of the Invention

[0004] To address the problems in the existing technology, such as poor sealing performance affecting ventilation in tunnels, ineffective exhaust of harmful gases, eddy currents from partitions causing duct wear and affecting service life, and difficulty in adapting to high-altitude, low-pressure environments, this invention provides a high-altitude, long-distance tunnel construction ventilation system and construction method.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: This invention proposes a ventilation system for high-altitude long-distance tunnel construction, comprising: a transverse tunnel, which is a construction auxiliary tunnel; a main tunnel, which includes a right-line main tunnel, a left-line main tunnel, and a pilot tunnel, which is the construction face, and the transverse tunnel and the main tunnel are arranged in an intersecting layout; a ventilation chamber, which adopts a full-section type, and the main tunnel and the ventilation chamber are arranged in an intersecting layout; a fan, which includes a main fan and several sets of supply fans, the main fan being fixed at the entrance of the transverse tunnel, the supply fans being fixed inside the ventilation chamber, and cooperating with the main tunnel to supply air to the main tunnel; and a duct, which includes an inlet duct and a supply duct, the inlet duct connecting the main fan and the ventilation chamber, the supply duct being fixedly connected to the ventilation chamber, and the supply duct running parallel to the main tunnel.

[0006] Preferably, it also includes a return air branch tunnel, the air outlet of which is inclined toward the horizontal tunnel, and the return air branch tunnel connects the main tunnel and the horizontal tunnel.

[0007] A construction method for a ventilation system for high-altitude, long-distance tunnel construction includes the following steps: S1 Construction Preparation: Collect basic data on tunnel engineering and plateau environmental parameters; S2 ventilation system parameter calculation: Based on basic data and environmental parameters, calculate the theoretical air volume required for the main tunnel and the air supply volume of the main fan and the exhaust fan, calculate the friction resistance, inflection point air pressure resistance and outlet dynamic pressure of the inlet duct and the exhaust duct, and determine the total pressure required by the main fan and the exhaust fan. S3 Ventilation System Design: Design the layout of the ventilation system; S4 air duct, main fan, and supply fan layout and installation: Fixed installation of air duct, main fan, and supply fan: S5 Duct Laying and Sealing: Lay the air inlet duct and air supply duct and ensure a seal; S6 ventilation system commissioning: Set the operating parameters of the main fan and the supply fan, and monitor the airflow smoothness, wind speed distribution and total pressure changes in the air chamber; S7 Ventilation Operation: Operate the ventilation system and monitor gas concentration to determine if it meets the requirements.

[0008] The preferred formula for calculating the theoretical required air supply volume at each working face in high-altitude areas is as follows: ; in, q The required ventilation volume per unit for workers at the tunnel face; n This represents the maximum number of personnel working simultaneously at the tunnel face. K y For correction factor, , Z This refers to altitude.

[0009] Preferably, the working face also needs to calculate the air supply volume per unit time based on the required air volume. The formula for calculating the air supply volume per unit time is: ; in, Q v Air volume required per unit time （m 3 / min) ; s This represents the maximum cross-sectional area of ​​the tunnel. v The minimum permissible wind speed inside the tunnel is set at 0.25 m / s.

[0010] Preferably, in step S2, the formula for calculating the air supply volume of the fan is: ; in, Q f Air supply volume to the fan (m³) 3 / min); Q 0 Air volume at the end of the pipeline (m³) 3 / min); β This represents the average air leakage rate per 100 meters. L This refers to the length of the duct.

[0011] Preferably, the dynamic pressure in step S2 includes three parts: the friction resistance along the duct, the inflection point pressure resistance, and the dynamic pressure at the outlet. When considering the friction resistance along the duct, the formula for calculating the friction resistance along the duct is: ; in, h f The pressure loss along the duct (P) a ), d The diameter of the duct (m) λ For the coefficient of friction of the air duct, ρ air density (kg / m³) β The average air leakage rate per 100 meters L For duct length, Q 0 Air volume at the end of the pipeline (m³) 3 / min); Without considering the friction resistance due to air leakage, the formula for calculating the friction resistance of a duct is: ; in, v The average flow velocity in the pipeline (m / s) is equal to half the sum of the inlet and outlet air volumes divided by the cross-sectional area of ​​the duct. The formula for calculating the inflection point wind pressure resistance is: ; in, ξ The local drag coefficient is ξ = 0.5(1 - S2 / S1). 2 , S1 and S2 The areas of the small and large cross sections (m²) are respectively. 2 ), ρ air density (kg / m³); The formula for calculating the dynamic pressure at the outlet is: ; in, v For the air velocity at the air outlet of the air duct, ρ air density (kg / m³).

[0012] Preferably, in step S2, the total pressure required by the fan is greater than the sum of the friction loss, the inflection point pressure loss, and the dynamic pressure at the outlet.

[0013] Preferably, step S2 further includes calculating the air volume required for blasting during construction. Due to the high altitude location, the required air volume for blasting during construction needs to be adjusted by multiplying the normal required air volume by [missing information]. The formula for calculating the required air volume for blasting operations in high-altitude areas is: ; in, t Ventilation time, G The amount of explosives used for full-face blasting, A For the maximum cross-sectional area of ​​the tunnel, L 0 For ventilation length, K y This is a correction factor for high-altitude areas. , Z This refers to altitude.

[0014] Preferably, step S2 further includes calculating the air volume required for internal combustion engine operation. Internal combustion engines include engineering vehicles such as excavators, loaders, and dump trucks. The calculation formula is as follows: ; in, K Air volume supplied per unit power of internal combustion machinery, 3m³ 3 / (min•kW); N i Power (kW) of each internal combustion engine; T i To calculate the working efficiency of the air volume required by the internal combustion equipment, the working efficiency of the excavator is taken as 0.2, the working efficiency of the loader is taken as 0.3, and the working efficiency of the dump truck is taken as 0.5.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a tunnel to construct a full-section ventilation chamber, with intake fans arranged in the transverse tunnel and exhaust fans arranged in the ventilation chamber. By turning the ventilation chamber into the main tunnel to deliver air, a relay ventilation system of "ventilation chamber + fan" is formed, making the ventilation chamber the core of airflow transfer and distribution. This effectively overcomes the resistance loss caused by low air pressure at high altitudes and long-distance air delivery, and achieves efficient delivery of fresh air and rapid discharge of toxic and harmful gases.

[0016] This invention uses an altitude correction coefficient to calculate various parameters within the ventilation system, providing more accurate parameter indicators for construction in high-altitude, low-pressure environments. This adapts the system to high-altitude, low-pressure environments, ensuring that the concentration of toxic and harmful gases inside the tunnel can be effectively and quickly reduced to below the standard levels, thus guaranteeing construction safety.

[0017] This invention adopts a full-section air chamber structure, which achieves a uniform and stable airflow field and high fan efficiency during air intake and exhaust. This reduces the wear of the airflow on the air duct, extends the service life of the air duct, and enables the rapid discharge of toxic and harmful gases, ensuring the safety of personnel during construction. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the construction method of the ventilation system of the present invention; Figure 2 This is a schematic diagram of the system layout of the present invention; Figure 3 This is a schematic diagram of the full-section wind tunnel of the present invention; Figure 4 This is a schematic diagram of the domed partition-type air chamber of the present invention; Figure 5 This is the unit mesh division diagram of the wind turbine model of the present invention; Figure 6 This is a full-section airflow trajectory diagram of the wind tunnel of the present invention; Figure 7 This is a diagram of the airflow trajectory of the arched partition-type air chamber of the present invention; Figure 8 This is the velocity cloud map at section M of the full-section wind tunnel of this invention; Figure 9 This is a velocity cloud map at section M of the arched partition-type wind tunnel of the present invention; Figure 10 This is a diagram showing the calculated wind speed at the inlet and outlet of the wind tunnel in this invention; Figure 11 This is the total pressure cloud diagram at section M of the full-section wind tunnel of this invention; Figure 12 This is the total pressure cloud diagram at section M of the arched partition-type air chamber of the present invention; Figure 13 This is a diagram showing the total pressure calculation results at the inlet and outlet of the air chamber in this invention; Figure 14 This is the dynamic pressure cloud diagram of the air supply duct outlet of the full-section air chamber of this invention; Figure 15 This is the dynamic pressure cloud diagram of the air supply duct of the dome-shaped baffle-type air chamber of the present invention; Figure 16 This is a distribution diagram of CO concentration in a tunnel at different ventilation times according to the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Horizontal tunnel; 2. Main fan; 3. Air inlet duct; 4. Air chamber; 5. Air supply fan; 6. Air supply duct; 7. Left main tunnel; 8. Horizontal guide tunnel; 9. Right main tunnel; 10. Return air branch tunnel; 11. M section line; 12. Baffle. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] like Figure 2-3 The diagram shows a ventilation system for high-altitude, long-distance tunnel construction, including a transverse tunnel 1 and a main tunnel. The construction area of ​​the main tunnel is the working face, and the transverse tunnel 1 is an auxiliary tunnel. From a top-down perspective, the transverse tunnel and the main tunnel are intersecting.

[0022] Specifically, Transverse Tunnel 1 is an auxiliary tunnel set up during the construction of long tunnels to shorten the construction period and increase the number of working faces. It is usually excavated laterally on the side of a valley or in a suitable terrain, and connects to the main tunnel in an orthogonal or oblique (angle > 40°) manner. Its main function is to achieve "shortening the length of the tunnel" by opening up multiple working faces to improve tunneling efficiency.

[0023] Specifically, the working face, also known as the tunnel face, is the working face that is continuously advanced during the construction of a tunnel or pit. It is a professional term in underground engineering such as mining and tunneling.

[0024] The main tunnels include the left main tunnel 7 and the right main tunnel 9, as well as the pilot tunnel 8. The left main tunnel 7, the pilot tunnel 8, and the right main tunnel 9 are all under construction at a large mileage. The construction face of the pilot tunnel 8 is more advanced than that of the construction faces of the left main tunnel 7 and the right main tunnel 9.

[0025] Specifically, the main tunnel is the core part of tunnel construction, and its excavation and support directly determine the main progress and functional realization of the project. In the construction of long tunnels, in order to improve efficiency, the "long tunnel, short construction" strategy is often adopted, which increases the working face by using auxiliary tunnels (such as inclined shafts and pilot tunnels). However, the main tunnel itself is the only structure that runs through both ends and ultimately forms the main structure for traffic or passage.

[0026] Specifically, a pilot tunnel is a small-section pilot tunnel parallel to the main tunnel, used for advanced geological forecasting, drainage and ventilation, and to increase construction access.

[0027] The tunnel at the intersection of the main tunnel and the transverse tunnel 1 is set up as a ventilation chamber 4. From a top-down perspective, the main tunnel and the ventilation chamber 4 are intersected. The ventilation chamber 4 serves as a transfer and relay chamber to better provide fresh and clean air to the main tunnel.

[0028] Specifically, the ventilation chamber 4 is a full-section structure that uses the entire tunnel section as the ventilation chamber cavity to achieve uniform airflow distribution and low resistance loss. The ventilation chamber 4 is composed of the tunnel at the intersection of the transverse tunnel 1 and the main tunnel. From a top-down perspective, the transverse tunnel 1 section that constitutes the ventilation chamber 4 is arranged perpendicularly to the main tunnel.

[0029] Specifically, the air chamber 4 is assembled from steel structural components to form a sealed cavity. The air chamber 4 must ensure that the cavity is flat and free of protruding obstacles, and that the cavity is tightly sealed with an air leakage rate of ≤0.5%. The installation position of the air chamber 4 should avoid the bends in the tunnel, and ensure that the air inlet pipe 3 is connected to the air chamber 4 at a 20° angle to reduce airflow impact loss.

[0030] It also includes fans and ducts. The fans include a main fan 2 and several sets of air supply fans 5. The ducts include an air inlet duct 3 and an air outlet duct 6.

[0031] The main fan 2 is fixed at the entrance of the transverse tunnel 1. The main fan 2 is fixedly connected to the air inlet pipe 3. The other end of the air inlet pipe 3 is fixedly connected to the air chamber 4. The main fan 2 sends clean and fresh air into the air chamber 4 through the air inlet pipe 3.

[0032] The blower 5 is fixed on the air chamber 4. The left main tunnel 7, the horizontal guide tunnel 8, and the right main tunnel 9 are respectively connected to the blower 5. The blower 5 is fixedly connected to the air supply pipe 6. The blower 5 uses the air supply pipe 6 to send the gas in the air chamber 4 to the construction sites of the left main tunnel 7, the horizontal guide tunnel 8, and the right main tunnel 9. The blower 5 discharges the toxic and harmful gases in the left main tunnel 7, the horizontal guide tunnel 8, and the right main tunnel 9.

[0033] The air inlet duct 3 and the air supply duct 6 are laid smoothly along the tunnel walls of the transverse tunnel 1 and the main tunnel, avoiding sharp bends. Fixed supports are installed every 5 to 10 meters to ensure that the air ducts do not collapse or twist. The interfaces of the air inlet duct 3 and the air supply duct 6 are all connected by flanges, and sealing gaskets are installed at the interfaces to ensure a tight seal, with the air leakage rate controlled within 1% per 100 meters.

[0034] Specifically, after the air inlet duct 3 and air outlet duct 6 are laid, a pressure test is used to detect air leakage, and any leaks are repaired in a timely manner to ensure that ventilation efficiency is not affected.

[0035] Specifically, the air inlet duct 3 and the air outlet duct 6 are made of flexible ducts, and the friction resistance coefficient of the ducts is controlled within 0.018.

[0036] Several sets of gas concentration monitoring devices are fixed in the horizontal tunnel 1, the left main tunnel 7, the horizontal pilot tunnel 8, and the right main tunnel 9 to monitor the internal gas quality.

[0037] Specifically, the gas concentration monitoring device is a CO sensor. CO concentration monitoring points are set every 50m at the construction face and in the transverse tunnel 1, left main tunnel 7, horizontal pilot tunnel 8, and right main tunnel 9. These points are used to monitor concentration changes at 5min, 10min, 15min, 20min, 25min, and 30min after ventilation begins, as well as for daily monitoring during construction.

[0038] Furthermore, in order to achieve better air supply to the main tunnel and provide fresh air, a return air branch tunnel 10 is also included. The air outlet of the return air branch tunnel 10 is inclined towards the direction of the transverse tunnel 1. The return air branch tunnel 10 is used to connect the main tunnel and the transverse tunnel 1.

[0039] Specifically, in tunnel engineering, the return air branch tunnel 10 is typically connected to the main tunnel or pilot tunnel, forming a complete ventilation network within the tunnel. The return air branch tunnel 10 serves as an auxiliary passage for exhausting stale air and introducing fresh air during tunnel construction. Its core function is to ensure that the air quality inside the tunnel meets safety standards through the construction of a ventilation system. A construction method for a high-altitude, long-distance tunnel construction ventilation system using a chamber-type ventilation system, as shown in the attached figure. Figures 1-16 As shown, it includes the following steps: S1 Construction Preparation: Collect basic data on the tunnel project and parameters of the plateau environment.

[0040] Specifically, during construction preparation, it is also necessary to confirm the basic parameters and prepare the relevant construction materials.

[0041] Specifically, basic data on tunnel engineering is collected, including tunnel elevation, burial depth, cross-sectional dimensions, single-heading excavation length, distribution of adits, number of working faces, personnel and machinery configuration, etc.

[0042] On-site measurements of plateau environmental parameters, including altitude, atmospheric pressure, and air density, provide a basis for calculating the required air volume correction.

[0043] Confirm basic parameters: Clarify basic parameters such as the number of workers on the tunnel face at the same time, the amount of blasting explosives used, the power of mechanical equipment, the cross-sectional area of ​​the tunnel, and the minimum allowable wind speed.

[0044] Prepare ventilation equipment and materials, including fans, ducts, steel structural components of air chamber 4, and corresponding sealing materials, to ensure that the equipment performance meets the requirements of high-altitude working conditions.

[0045] S2 ventilation system parameter calculation: Based on basic data and environmental parameters, calculate the theoretical air supply volume required for each construction face and the air supply volume of main fan 2 and air supply fan 5. Calculate the friction resistance, inflection point air pressure resistance and outlet dynamic pressure of inlet duct 3 and air supply duct 6, and determine the total pressure required by main fan 2 and air supply fan 5.

[0046] Specifically, the calculations need to be corrected based on the characteristics of high-altitude areas, and the correction factor is required. K y The calculation formula is: ,in Z This refers to altitude.

[0047] Specifically, based on the characteristics of high-altitude areas, the theoretical air supply volume required for each tunnel face in high-altitude areas, namely, the left main tunnel 7, the horizontal pilot tunnel 8, and the right main tunnel 9, is calculated using the following formula: ; in, q The required ventilation volume per unit for workers at the tunnel face; n This represents the maximum number of personnel working simultaneously at the tunnel face. K y This is a correction factor.

[0048] Furthermore, based on the required air volume, the air supply volume per unit time at the working face also needs to be calculated. Specifically, the formula for calculating the air supply volume per unit time in the left main tunnel 7, horizontal guide tunnel 8, and right main tunnel 9 is as follows: ; in, Q v The required air volume per unit time (m³) 3 / min); s This represents the maximum cross-sectional area of ​​the tunnel. v The minimum permissible wind speed inside the tunnel is set at 0.25 m / s.

[0049] Specifically, based on the characteristics of high-altitude areas, the air supply volume of the fan needs to be calculated. The calculation formula is as follows: ; in, Q f Air supply volume to the fan (m³) 3 / min); Q 0 Air volume at the end of the pipeline (m³) 3 / min); β This represents the average air leakage rate per 100 meters. L This refers to the length of the duct.

[0050] Specifically, the duct friction resistance, inflection point pressure resistance, and outlet dynamic pressure are calculated as follows: When considering the friction resistance along the duct, the formula for calculating the friction resistance along the duct is: ; in, h f The pressure loss along the duct (Pa) d The diameter of the duct (m) λ For the coefficient of friction of the air duct, ρ air density (kg / m³) β The average air leakage rate per 100 meters L For duct length, Q 0 Air volume at the end of the pipeline (m³) 3 / min); Without considering the friction resistance due to air leakage, the formula for calculating the friction resistance of a duct is: ; in, v The average flow velocity in the pipeline (m / s) is equal to half the sum of the inlet and outlet air volumes divided by the cross-sectional area of ​​the duct. The formula for calculating the inflection point wind pressure resistance is: ; in, ξ The local drag coefficient is ξ = 0.5(1 - S2 / S1). 2 , S1 and S2 The areas of the small and large cross sections (m²) are respectively. 2 ), ρ air density (kg / m³); The formula for calculating the dynamic pressure at the outlet is: ; in, v For the air velocity at the air outlet of the air duct, ρ air density (kg / m³).

[0051] It should be noted that the total pressure required by the fan is greater than the sum of the friction loss, the inflection point pressure loss, and the dynamic pressure at the outlet.

[0052] Specifically, the calculation of the required air volume for blasting during construction needs to be adjusted due to the high altitude of the location. It needs to be multiplied by a certain factor from the normal required air volume. The formula for calculating the required air volume for blasting operations in high-altitude areas is: ; in, t Ventilation time, G The amount of explosives used for full-face blasting, A L0 is the maximum cross-sectional area of ​​the tunnel, and L0 is the ventilation length. K y This is a correction factor for high-altitude areas.

[0053] Specifically, this also includes calculating the air volume required for internal combustion engine operations. Internal combustion engines include engineering vehicles such as excavators, loaders, and dump trucks. The calculation formula is as follows: ; in, K Air volume supplied per unit power of internal combustion machinery, 3m³ 3 / (min•kW); N i Power (kW) of each internal combustion engine; T i To calculate the working efficiency of the air volume required by the internal combustion equipment, the working efficiency of the excavator is taken as 0.2, the working efficiency of the loader is taken as 0.3, and the working efficiency of the dump truck is taken as 0.5.

[0054] S3 Ventilation System Design: Determine the structure of the ventilation chamber and design the layout of the ventilation system.

[0055] Specifically, based on the calculation results in step S2, a model of wind cell 4 is constructed, including a full-section wind cell and a domed partition wind cell model. Through simulation using FLOW SIMULATION software or on-site testing, the airflow trajectory inside wind cell 4 is optimized, and the wind speed inside wind cell 4 is simulated to ensure better airflow smoothness inside wind cell 4, thereby achieving higher operating efficiency of the main fan 2 and the blower 5.

[0056] Specifically, the calculation results in step S2 are compared separately: Full-section ventilation chamber: The full-section ventilation chamber design uses the entire tunnel cross-section as a ventilation chamber cavity. Fresh air flowing in from the air inlet pipe enters the ventilation chamber, is redistributed and pressurized, and then delivered to the three working faces. The cross-section of the ventilation chamber is shown in the attached figure. Figure 3 As shown.

[0057] Arched diaphragm type ventilation chamber: The arched diaphragm type ventilation chamber design utilizes horizontal diaphragms to divide the tunnel cross-section into upper and lower parts. The upper part serves as the air intake channel. Fresh air flowing in through the air intake duct enters the ventilation chamber, is redistributed and pressurized, and then delivered to the three working faces. The cross-section of the ventilation chamber is shown in the attached figure. Figure 4 As shown.

[0058] Comparative analysis of wind turbine structural parameters: A 1:1 numerical model was established using SOLIDWORKS software. The model was then imported into FLOWSIMULATION software. Boundary conditions were set for the model. Since the airflow through the inlet duct 3 of the transverse tunnel 1 forms a 20° angle with the air chamber 4, the inlet airflow velocity was set to 13.96 m / s in the X direction and 5.081 m / s in the Z direction. The atmospheric pressure at a plateau altitude of 3400 m was calculated, and the outlet environmental pressure was set to 62760 Pa. The model was then meshed. Figure 5 As shown, the final calculation is performed.

[0059] The intersection of the center of the air inlet duct and the center of the air supply duct is calculated as section M11.

[0060] Comparison of airflow traces between full-section and dome-shaped baffle types: Analysis using FLOW SIMULATION software yielded airflow trajectory diagrams for both the full-section wind tunnel and the domed baffle wind tunnel, as shown in the attached figures. Figures 6-7 As shown; As can be seen from the airflow trajectory diagram, the airflow distribution of the full-section air chamber is more dense. After the airflow reaches the end face of the air chamber, it presents a spiral return flow, which easily reaches the air outlet. The airflow distribution of the dome-shaped baffle air chamber is relatively sparse. After reaching the cross-section of the air chamber, it mostly presents a straight return flow, which is not easy to flow into the air outlet and is easy to form vortices.

[0061] Comparison of wind speeds between full-section and domed diaphragm types: Analysis using FLOW SIMULATION software reveals velocity contour maps at section M for both the full-section and domed diaphragm types, as shown in the attached diagram. Figures 8-9 As shown; In terms of the scope of influence, the wind speed impact range of the full-section ventilation system extends to the middle of the right-line main tunnel and the horizontal guide tube, while the wind speed impact range of the arched diaphragm ventilation system covers the entire side area of ​​the duct. The impact range decreases at the horizontal guide tube. In terms of the pattern of influence, the wind speed impact of the full-section ventilation system gradually decreases from the air inlet to the duct along the width of the ventilation system and also gradually decreases along the length of the ventilation system, gradually approaching zero in the middle of the right-line main tunnel and the horizontal guide tube. The wind speed impact of the arched diaphragm ventilation system is the highest in the middle of the side area from the air inlet to the duct, gradually decreasing towards both sides and also gradually decreasing along the length of the ventilation system, only approaching zero at the left-line main tunnel. Numerically, the calculated speeds at the inlet and outlet are summarized as follows (see attached figure). Figure 10 As shown in the analysis and comparison, the wind speed difference at the inlet and outlet of the full-section wind cell is smaller than that of the dome-shaped baffle type. Therefore, the dynamic pressure loss in the full-section wind cell is smaller, the airflow smoothness in the wind cell is better, and the operating efficiency of the fan is higher.

[0062] Comparison of total pressure between full-section type and dome-shaped diaphragm type: Analysis using FLOW SIMULATION software reveals the total pressure cloud diagrams at section M for both full-section and arched diaphragm types, as shown in the attached diagram. Figures 11-12 As shown; In terms of the scope of influence, the total pressure of the full-section ventilation shaft is close to atmospheric pressure, appearing in the entire area from the right main tunnel to the horizontal guide duct. The total pressure of the arched diaphragm ventilation shaft is also close to atmospheric pressure, but only affects 3 / 5 of the area from the right main tunnel to the horizontal guide duct. In terms of the pattern of influence, the total pressure of the full-section ventilation shaft gradually decreases along the width of the shaft from the inlet to the side area where the duct is located, and then first decreases and then increases along the length. The total pressure of the arched diaphragm ventilation shaft shows a gradual decrease in the entire side area at the duct, and then first decreases and then increases along the length of the shaft. Numerically, the calculated total pressure at the inlet and outlet is summarized as follows (see attached figure). Figure 13As shown in the figure, the total pressure difference between the inlet and outlet of the full-section air chamber is greater than that of the domed baffle air chamber. Therefore, the full-section air chamber has higher fan efficiency, better fan coordination, and a smoother airflow field inside the air chamber.

[0063] Comparison of dynamic pressure between full-section and domed diaphragm air supply ducts: Analysis using FLOW SIMULATION software reveals dynamic pressure cloud maps at the air supply duct inlets for both full-section and domed diaphragm types, as shown in the attached diagram. Figures 14-15 As shown; Analysis and comparison show that, in terms of the scope of impact, the dynamic pressure of the full-section air chamber air supply duct impacts the duct wall less than that of the dome-shaped baffle type, resulting in less friction loss, providing more fresh air to the working face, less wear on the duct, and a longer service life. In terms of numerical values, the dome-shaped baffle type has higher dynamic pressure, which means the blower consumes more power and the ventilation energy loss is greater.

[0064] Comparison of ventilation effects during air chamber construction: by Figure 2 Based on this, the construction ventilation effects of full-section and arch-top diaphragm-type ventilation systems were tested. After the intersection of the transverse tunnel 1 and the main tunnel, construction was carried out for 4634m in the right main tunnel 9, 4971m in the pilot tunnel 8, and 4606m in the left main tunnel. Numerical simulations were performed within a 300m range during the construction process. A three-dimensional numerical model of the ventilation system for high-altitude long-distance tunnel construction was established. Test sections were set at 50m intervals at the tunnel face at the three mileages to monitor the changes in CO concentration inside the tunnel. The CO concentration distribution inside the tunnel after 5min, 10min, 15min, 20min, 25min, and 30min of ventilation is shown below. Figure 16 As shown, with the increase of ventilation time, the peak CO concentration in the tunnel gradually moves away from the tunnel face.

[0065] When using a full-section ventilation system, the average CO concentration inside the tunnel was below the national standard of 30 mg / m³ after 20 minutes of ventilation. However, when using a vaulted diaphragm ventilation system, the average CO concentration inside the tunnel only fell below the national standard of 30 mg / m³ after 25 minutes of ventilation. After 30 minutes of ventilation, the CO inside the tunnel was essentially completely eliminated.

[0066] In summary, the ventilation effect of the full-section air chamber is better than that of the dome-shaped partition air chamber, so air chamber 4 adopts a full-section structure.

[0067] Specifically, the air chamber 4, as the core of airflow transfer and distribution, receives fresh air delivered by the front-end main fan 2 and, through its internal full-section structure flow field, effectively reduces airflow eddies and resistance losses, evenly distributing the air to the blowers on each working face. This achieves a relay ventilation process of "main fan air supply → air chamber distribution and pressurization → blower air outlet", extending the effective ventilation distance.

[0068] S4 air chamber 4, main fan 2, and blower 5 arrangement and installation: arrangement and installation of air chamber 4, main fan 2, and blower 5.

[0069] Specifically, the air chamber 4 is assembled from steel structural components and is a fully enclosed cavity. The air chamber 4 must ensure that the cavity is flat and free of protruding obstacles. The installation position should avoid the bend of the horizontal hole 1 and ensure that the air inlet pipe 3 is connected to the air chamber 4 at a 20° angle to reduce airflow impact loss. The air chamber 4 cavity is tightly sealed with an air leakage rate of ≤0.5%.

[0070] Specifically, both the main fan 2 and the supply fan 5 are axial flow fans. During installation, ensure that the foundation is firm and level. Ensure that the air outlet of the main fan 2 and the air inlet pipe 3, and the air outlet of the supply fan 5 and the air supply pipe 6 are tightly sealed to reduce air leakage. The main fan 2 is located in the fresh air area at the entrance of the transverse tunnel 1, and the supply fan 5 is located in the air chamber 4 near the interface of the supply pipe 6 to facilitate rapid airflow distribution.

[0071] Specifically, the main fan 2 is a Yutielong axial flow fan of model ZVN1-16-300 / 4; the blowers 5 of the left main tunnel 7 and the right main tunnel 9 are Yutielong axial flow fans of model ZVN1-14-90 / 4; and the blower 5 of the horizontal guide tunnel 8 is a Yutielong axial flow fan of model ZVN1-12-75 / 4.

[0072] Specifically, it is also equipped with a CHNG-100KVA jet fan voltage reducer to enable the main fan 2 and the blower 5 to work better, achieve stable operation of the main fan 2 and the blower 5, with vibration value ≤4.5mm / s, noise ≤85dB (A); and fan efficiency ≥85%.

[0073] S5 Ductwork Laying and Sealing: Lay inlet duct 3 and supply duct 6 and ensure sealing.

[0074] Specifically, the air inlet duct 3 and the air supply duct 6 are laid smoothly along the tunnel walls of the transverse tunnel 1 and the main tunnel, avoiding sharp bends. Fixed supports are installed every 5 to 10 meters to ensure that the ducts do not collapse or twist. The interfaces of the air inlet duct 3 and the air supply duct 6 are all connected by flanges, and sealing gaskets are installed at the interfaces to ensure a tight seal, with the air leakage rate controlled within 1% per 100 meters.

[0075] Specifically, after the air inlet duct 3 and air outlet duct 6 are laid, a pressure test is used to detect air leakage, and any leaks are repaired in a timely manner to ensure that ventilation efficiency is not affected.

[0076] Specifically, the air inlet duct 3 and the air outlet duct 6 are made of flexible ducts, and the friction resistance coefficient of the ducts is controlled within 0.018.

[0077] S6: Ventilation system commissioning: Set the operating parameters of the main fan 2 and the supply fan 5, and monitor the airflow smoothness, wind speed distribution and total pressure changes in the air chamber 4; Specifically, based on the calculation results in step S2, the operating frequencies of the main fan 2 and the blower 5 are set to ensure that the airflow velocity in the inlet duct meets the design requirements.

[0078] Specifically, for different working conditions, such as smoke exhaust after blasting or ventilation during normal tunneling, the operating parameters of the main fan 2 and the blower 5 are adjusted. For example, after blasting, the air supply volume needs to be increased and the smoke exhaust time shortened. During normal tunneling, a stable air supply needs to be maintained to ensure that the wind speed and gas concentration in the tunnel meet the standards.

[0079] S7 Normal ventilation operation: Operate the ventilation system and monitor the gas concentration to determine whether it is qualified.

[0080] Specifically, in daily operation, the ventilation system runs continuously 24 hours a day, and a dedicated person is assigned to regularly check the operating status of the fans, the sealing of the air ducts, and the ventilation effect inside the cave. Any problems such as fan failure or air duct damage are dealt with in a timely manner.

[0081] Specifically, gas concentration monitoring involves setting up CO concentration monitoring points every 50m at each construction face and inside the transverse tunnel 1, left main tunnel 7, horizontal pilot tunnel 8, and right main tunnel 9. Concentration changes are monitored at 5, 10, 15, 20, 25, and 30 minutes after ventilation to ensure that the CO concentration in ventilation chamber 4 drops below 30mg / m³ within 20 minutes of ventilation.

[0082] Specifically, the gas concentration inside the cave is detected, and the results are used to determine whether the standard is met. If the standard is met, the current normal ventilation operation parameters are maintained.

[0083] Specifically, when the gas concentration detection inside the cave fails to meet the standard, the ventilation parameters are adjusted in a timely manner, that is, the operating parameters of the main fan 2 and the blower 5 are adjusted, and continuous monitoring is maintained. After adjusting the ventilation parameters, the ventilation chamber 4 is ventilated for 20 minutes, and the monitoring data is judged. If it is qualified, the current ventilation operation is maintained; if it is not qualified, the ventilation parameters are adjusted again according to the calculation results.

[0084] When using the above methods for construction, attention should also be paid to safety and environmental protection measures.

[0085] Specifically, ensure equipment safety and electrical safety by regularly maintaining and inspecting equipment and lines to ensure their safe operation. Line installation should be dustproof and moisture-proof, and wear and tear should be avoided after installation.

[0086] Specifically, regarding personnel safety protection, construction workers must wear protective equipment such as gas masks and dust masks when entering the tunnel, and must receive safety training; necessary emergency escape facilities must be installed inside the tunnel.

[0087] Specifically, waste disposal should be managed and processed in a unified manner to ensure that the treated waste is safe and harmless.

[0088] Specifically, ventilation inside the tunnel will be enhanced to ensure that the dust concentration inside the tunnel meets environmental protection standards, and dust purification devices will be installed at the tunnel entrance to avoid environmental pollution.

[0089] Specifically, other safety and environmental protection measures must comply with construction requirements and specifications.

[0090] It should be noted that the construction method of the ventilation system for high-altitude long-distance tunnel construction of this invention is applicable to long-distance tunnel projects with an altitude of 3,000 meters and above, a single-heading excavation length of more than 2,000 meters, and multiple working faces constructed in parallel. It is especially suitable for ventilation construction of high-altitude tunnels with large tunnel cross sections, dense branch tunnels, concentrated construction machinery and personnel, and frequent blasting operations. Through precise calculation, it can effectively solve problems such as insufficient ventilation and oxygen supply and accumulation of toxic gases in plateau environments.

[0091] Examples of implementation of this invention: The invention is being used in ventilation construction at the No. 1 cross passage of the KY Tunnel in the plateau railway project. The No. 1 cross passage has three working faces: working face one is constructing 4634m towards the right-line main tunnel at the major mileage direction; working face two is constructing 4921m towards the horizontal pilot tunnel at the major mileage direction; and working face three is constructing 4596m towards the left-line main tunnel at the major mileage direction. The tunnel is being constructed using the full-face method, with large-scale mechanized construction.

[0092] This project adopts this construction method for ventilation construction, and selects a full-section air chamber structure. One axial flow main fan (with air supply through a 2.8m diameter duct) is arranged at the entrance of the No. 1 cross tunnel. Three distribution fans are arranged in the air chamber, and air is supplied to each working face through 2.0m diameter (main tunnel) and 1.6m diameter (horizontal guide) ducts respectively.

[0093] Based on altitude correction calculations, the required air volume for the main tunnel face is determined to be 1336.8 m³ / min, and the required air volume for the guide tunnel face is 747.6 m³ / min. The air supply volume of the fans, after correction based on the air leakage rate, meets the design requirements.

[0094] The following effects are achieved by using this construction method: (1) Ventilation efficiency: After the full-section ventilation system is in operation, the airflow field in the tunnel is uniform and stable, the friction loss is small, the fresh air supply at the working face is sufficient, and the minimum wind speed in the tunnel is ≥0.25m / s.

[0095] (2) Gas exhaust: Within 20 minutes after the blast, the CO concentration at each working face dropped to below 30 mg / m³, meeting the national standard requirements, and the exhaust time was shortened by 5 to 10 minutes compared with the traditional ventilation method.

[0096] (3) Equipment wear: During the operation of the ventilation system, the wear of the air duct is small, there is no obvious air leakage, the fan operating efficiency is stable at over 88%, and the energy consumption is reduced by 18% compared to expectations.

[0097] (4) Construction safety: No safety accidents such as oxygen deficiency or poisoning by toxic gases occurred during the entire construction process. The incidence of altitude sickness among construction workers was significantly reduced, the project progressed smoothly, and the tunneling task was completed on schedule.

[0098] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A ventilation system for high-altitude, long-distance tunnel construction, characterized in that, include, The cross passage is a construction auxiliary passage; The main tunnel includes a right-line main tunnel, a left-line main tunnel, and a pilot tunnel. The main tunnel is the construction face, and the transverse tunnels intersect with the main tunnel. The air chamber adopts a full-section structure, and the main tunnel and the air chamber are arranged in an intersecting layout; The fan includes a main fan and several sets of blowers. The main fan is fixed at the entrance of the transverse tunnel, and the blowers are fixed inside the air chamber and cooperate with the main tunnel to supply air to the main tunnel. The air duct includes an air inlet duct and an air outlet duct. The air inlet duct connects the main fan to the air chamber, and the air outlet duct is fixedly connected to the air chamber. The direction of the air outlet duct is parallel to the main tunnel.

2. The high-altitude long-distance tunnel construction wind-bin type ventilation system according to claim 1, characterized in that, It also includes a return air branch tunnel, the air outlet of which is inclined towards the horizontal tunnel, and the return air branch tunnel connects the main tunnel and the horizontal tunnel.

3. A construction method of a high-altitude long-distance tunnel construction air-warehouse type ventilation system, based on the high-altitude long-distance tunnel construction air-warehouse type ventilation system of claim 1, characterized in that, Includes the following steps: S1 Construction Preparation: Collect basic data on tunnel engineering and plateau environmental parameters; S2 ventilation system parameter calculation: Based on basic data and environmental parameters, calculate the theoretical air volume required for the main tunnel and the air supply volume of the main fan and the exhaust fan, calculate the friction resistance, inflection point air pressure resistance and outlet dynamic pressure of the inlet duct and the exhaust duct, and determine the total pressure required by the main fan and the exhaust fan. S3 Ventilation System Design: Determine the structure of the ventilation chamber and design the layout of the ventilation system; S4 air duct, main fan, and supply fan layout and installation: Fixed installation of air duct, main fan, and supply fan: S5 Duct Laying and Sealing: Lay the air inlet duct and air supply duct and ensure a seal; S6 ventilation system commissioning: Set the operating parameters of the main fan and the supply fan, and monitor the airflow smoothness, wind speed distribution and total pressure changes in the air chamber; S7 Ventilation Operation: Operate the ventilation system and monitor gas concentration to determine if it meets the requirements.

4. The construction method of the ventilation system for high-altitude long-distance tunnel construction according to claim 3, characterized in that, The theoretical required air supply quantity calculation formula of each working face in high altitude area is: ; in, q The required ventilation volume per unit for workers at the tunnel face; n This represents the maximum number of personnel working simultaneously at the tunnel face. K y For correction factor, , Z This refers to altitude.

5. The construction method of the ventilation system for high-altitude long-distance tunnel construction according to claim 4, characterized in that, The working face also needs to calculate the air supply volume per unit time based on the required air volume. The formula for calculating the air supply volume per unit time is: ; in, Q v Air volume required per unit time （m 3 / min) ; s This represents the maximum cross-sectional area of ​​the tunnel. v The minimum permissible wind speed inside the tunnel is set at 0.25 m / s.

6. The construction method of the ventilation system for high-altitude long-distance tunnel construction according to claim 3, characterized in that, In the step S2, the fan air supply amount calculation formula is: ; in, Q f Air supply volume to the fan (m³) 3 / min); Q 0 Air volume at the end of the pipeline (m³) 3 / min); β This represents the average air leakage rate per 100 meters. L This refers to the length of the duct.

7. The high-altitude long-distance tunnel construction air-bunker type ventilation system construction method according to claim 3, characterized in that, In step S2, the dynamic pressure includes three parts: the friction resistance along the duct, the inflection point pressure resistance, and the dynamic pressure at the outlet. When considering the along-path resistance of air leakage, the calculation formula of the along-path resistance of the air pipe is: ; wherein, h f is the pressure loss along the duct (P a ), d is the duct diameter (m), λ is the duct friction coefficient, ρ is the air density (kg / m3), β is the average value of the air leakage rate per 100 m, L is the duct length, Q 0 is the air flow at the end of the duct (m 3 / min). Without considering the friction resistance due to air leakage, the formula for calculating the friction resistance of a duct is: ; in, v The average flow velocity in the pipeline (m / s) is equal to half the sum of the inlet and outlet air volumes divided by the cross-sectional area of ​​the duct. The formula for calculating the inflection point wind pressure resistance is: ; in, ξ The local drag coefficient is ξ = 0.5(1 - S2 / S1). 2 , S1 and S2 The areas of the small and large cross sections (m²) are respectively. 2 ), ρ air density (kg / m³); The formula for calculating the dynamic pressure at the outlet is: ; in, v For the air velocity at the air outlet of the air duct, ρ air density (kg / m³).

8. The construction method of the ventilation system for high-altitude long-distance tunnel construction according to claim 7, characterized in that, In step S2, the total pressure required by the fan is greater than the sum of the friction loss, the inflection point pressure loss, and the dynamic pressure at the outlet.

9. The construction method of the ventilation system for high-altitude long-distance tunnel construction according to claim 3, characterized in that, Step S2 also includes calculating the air volume required for blasting during construction. Due to the high altitude, the required air volume for blasting during construction needs to be adjusted by multiplying the normal required air volume by a certain factor. The formula for calculating the required air volume for blasting operations in high-altitude areas is: ; in, t Ventilation time, G The amount of explosives used for full-face blasting, A For the maximum cross-sectional area of ​​the tunnel, L 0 For ventilation length, K y This is a correction factor for high-altitude areas. , Z This refers to altitude.

10. The construction method of the ventilation system for high-altitude long-distance tunnel construction according to claim 3, characterized in that, Step S2 also includes calculating the air volume required for internal combustion engine operation. Internal combustion engines include engineering vehicles such as excavators, loaders, and dump trucks. The calculation formula is as follows: ; in, K Air volume supplied per unit power of internal combustion machinery, 3m³ 3 / (min•kW); N i Power (kW) of each internal combustion engine; T i To calculate the working efficiency of the air volume required by the internal combustion equipment, the working efficiency of the excavator is taken as 0.2, the working efficiency of the loader is taken as 0.3, and the working efficiency of the dump truck is taken as 0.5.

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