A ventilation method for multi-face construction in ultra-deep vertical shaft areas of extra-long railway tunnels

Abstract

This invention relates to a ventilation method for multi-face construction in an ultra-deep vertical shaft of an extra-long railway tunnel. Based on a construction area model and through characteristic pollutant transport simulation, the ventilation system structure in the construction area is determined. Corresponding air door opening and closing are controlled according to different construction scenarios. Axial flow fans are arranged in the ventilation duct, which is located between the auxiliary shaft and the auxiliary shaft yard. Jet fans are arranged in the transport roadways of the main shaft yard. Air ducts are led out from the axial flow fans and laid along the main tunnel wall, passing through the rigid air walls in the two transverse passages closest to the ventilation duct, and laid along the guide wall towards the smaller and larger mileage directions respectively. The main tunnel and the guide are arranged side-by-side. Rigid air walls are arranged in the ventilation duct and the two transverse passages closest to the ventilation duct. Temporary air doors are arranged in the two transverse passages closest to the ventilation duct. Linkage air doors are arranged in the two transport roadways of the auxiliary shaft yard.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction ventilation technology, specifically a method for ventilation of multiple working faces in the construction area of ​​an ultra-deep vertical shaft in an extra-long railway tunnel. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] When a long railway tunnel traverses a thick mountain with poorly developed transverse gullies, and the tunnel's central cross passages and inclined shafts are excessively long, making it difficult to accelerate tunnel excavation, it is necessary to construct a vertical shaft in the middle of the tunnel. This shaft work area can then expedite the main tunnel construction, thereby shortening the overall construction period. Long railway tunnels typically have great burial depths, resulting in deep construction shafts; there are already engineering cases with depths exceeding 700 meters.

[0004] During the construction of such tunnels, if the tunnel shaft work area is set up with two shafts, it typically has a bottom annular parking area, a main tunnel, and a pilot tunnel. The bottom annular parking area is connected to the main tunnel, the pilot tunnel, and the main and auxiliary shafts, forming a complex spatial structure with multiple working faces intersecting and connecting. This structure is affected by factors such as the vertical transportation construction method and the maximum ventilation limit distance. Traditional forced ventilation is not suitable for tunnel shaft work areas set up with two shafts (especially in the construction stage before it is connected to adjacent work areas). Therefore, during the normal construction period, tunnel ventilation is usually adopted for ventilation and sewage discharge of the working faces in tunnel shaft work areas set up with two shafts.

[0005] Meanwhile, tunnel shaft work areas often have significant elevation differences, resulting in increased air loss along the way when fresh air is introduced into the underground work area through ducts or shafts. Shaft openings are typically located at higher altitudes where the air is thinner, requiring larger ventilation volumes to meet the needs of workers in the underground tunnels for normal ventilation and dust removal and cooling. Furthermore, the interconnected spatial structure of multiple chambers, forming multiple working faces and converging areas, leads to chaotic airflow development, causing pollutants to easily remain within the chambers, resulting in generally poor overall ventilation and wastewater removal efficiency. Summary of the Invention

[0006] To address the technical problems mentioned above, this invention provides a ventilation method for multi-face construction in ultra-deep vertical shaft areas of extra-long railway tunnels. Based on the different construction scenarios of multiple working faces, different states of the tunnel-type ventilation system are activated to meet the ventilation and sewage discharge needs under various construction scenarios. By optimizing the airflow organization of the tunnel-type ventilation system under different construction scenarios in ultra-deep vertical shaft areas, the method improves the effect of pollutant ventilation control, providing a reference for the formulation of ventilation control strategies for underground construction areas of ultra-deep vertical shafts in extra-long railway tunnels and similar projects.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a method for ventilation during construction in multi-faceted work areas of ultra-deep vertical shafts in extra-long railway tunnels, comprising the following steps:

[0009] A model is established based on the parameters of the work area. The transport of characteristic pollutants is simulated under the set boundary conditions. Based on the simulation results, the layout structure of the ventilation system in the work area is determined.

[0010] Switch the corresponding damper switches in the ventilation system according to different work site construction scenarios;

[0011] The layout structure of the ventilation system includes:

[0012] Axial flow fans are installed in ventilation ducts located between the auxiliary shaft and the auxiliary shaft yard; jet fans are installed in the transport roadways of the main shaft yard.

[0013] The ducts are led out from the axial flow fan unit and laid along the wall of the main tunnel. After passing through the rigid wind wall, the ducts are laid along the wall of the horizontal guide in the direction of small mileage and large mileage respectively. The main tunnel and the horizontal guide are arranged side by side.

[0014] Rigid air walls are arranged in the ventilation duct and the two cross passages closest to the ventilation duct; temporary air doors are arranged in the two cross passages next to the ventilation duct; and linkage air doors are arranged in the two transport roadways of the auxiliary shaft yard. Each set of linkage air doors includes two linkage-controlled air doors. During operation, at least one of the two air doors remains closed.

[0015] Furthermore, depending on the different construction work scene and actual passage requirements, the corresponding air dampers are switched to open or close, and the axial flow fan is activated to introduce fresh air to the outside through the ventilation duct and the auxiliary shaft. The fresh air is then sent to the work face through the air duct. The jet fan is turned on or off as needed to drive the generated sludge to be discharged through the main shaft.

[0016] Furthermore, the model established based on the work area parameters includes the following steps:

[0017] The main tunnel and pilot tunnel are set up side by side, with multiple sets of cross passages between them. With the ventilation duct as the boundary, the cross passages along the small mileage direction are X01, X02...Xn, and the cross passages along the large mileage direction are D01, D02...Dn.

[0018] The bottom of the main shaft and the horizontal guide have transport roadways facing the large mileage and small mileage directions respectively. Each set of transport roadways is equipped with a corresponding slag transfer yard. The two transport roadways and the horizontal guide form a ring-shaped main shaft yard, which is connected to the main shaft.

[0019] The bottom of the auxiliary shaft is connected to the main tunnel by transport tunnels facing the high mileage and low mileage directions respectively. A ventilation duct is also provided between the two sets of transport tunnels. The transport tunnels in the two directions form a ring-shaped auxiliary shaft yard with the main tunnel, and the auxiliary shaft yard is connected to the auxiliary shaft.

[0020] Furthermore, in each set of interconnected air doors, the air door closest to the main tunnel is a normally closed air door, and the other air door is a normally open air door.

[0021] Furthermore, the bottom of the auxiliary shaft is the underground gate tunnel, which is connected to the shaft of the auxiliary shaft. The space above the gate tunnel is connected to the horizontally arranged large-section ventilation duct through a small-section ventilation duct with a set inclination angle. The axial flow fan is arranged in the horizontally arranged large-section ventilation duct.

[0022] Furthermore, the rigid air wall is made of rigid material and is sealed to the air duct. The rigid air wall is used to block gas from flowing through the channel from the space outside the air duct.

[0023] Furthermore, the linkage damper device is a pressureless damper, including at least two dampers with linkage control. The two dampers have a set distance between them. When one damper is closed, the other damper is linked to open. During the operation, at least one of the two dampers is in the closed state.

[0024] Furthermore, the multi-face construction scenario includes a two-way four-face construction scenario. In the two-way four-face construction scenario, the axial flow fan unit is started, and fresh air from the auxiliary shaft is supplied to the working face through the ventilation duct.

[0025] During construction, temporary air doors shall remain open, and at least one air door in each set of linked air doors shall remain closed.

[0026] When the difference in excavation progress between the working faces of the pilot tunnel or the main tunnel exceeds the set range, the jet fan at the entrance of the slag dump on the side with faster construction progress is turned on to balance the airflow and air pressure by diverting the sewage air.

[0027] Furthermore, the multi-face construction scenario includes a two-way double-face construction scenario. In the two-way double-face construction scenario, the axial flow fan unit is started, and fresh air from the auxiliary shaft is supplied to the working face through the ventilation duct.

[0028] During construction, if there is a working face in the main tunnel, the temporary air doors facing the construction direction of the main tunnel shall remain open; otherwise, the temporary air doors shall remain closed. In each set of linked air doors, at least one air door shall remain closed.

[0029] When the difference in excavation progress between the working faces of the pilot tunnel or the main tunnel exceeds the set range, the jet fan at the entrance of the slag dump on the side with faster construction progress is turned on to balance the airflow and air pressure by diverting the sewage air.

[0030] Furthermore, multi-face construction scenarios also include bidirectional three-face construction scenarios. In bidirectional three-face construction scenarios, axial flow fans are started, and fresh air from the auxiliary shaft is supplied to the working face through ventilation ducts.

[0031] During construction, if there is a working face in the main tunnel, the temporary air doors facing the construction direction of the main tunnel shall remain open; otherwise, the temporary air doors shall remain closed. In each set of linked air doors, at least one air door shall remain closed.

[0032] The jet fan on one side of the double-working-face construction is turned on to direct the drainage of sewage.

[0033] Furthermore, multi-face construction scenarios also include unidirectional double-face construction scenarios. In the unidirectional double-face construction scenario, the axial flow fan corresponding to the construction side is turned on, and fresh air from the auxiliary shaft is supplied to the working face through the ventilation duct.

[0034] During construction, temporary air doors in the direction of construction shall remain open, while temporary air doors in the direction of non-construction shall be closed. Among the linked air doors, at least one air door shall remain closed.

[0035] The jet fan on one side of the double-working-face construction is turned on to direct the drainage of sewage.

[0036] Furthermore, in addition to multi-face construction scenarios, it also has a single-face construction scenario. In a single-face construction scenario, the axial flow fan corresponding to the construction side is turned on, and fresh air from the auxiliary shaft is supplied to the working face through the ventilation duct.

[0037] During construction, if there is a working face in the main tunnel, the temporary air doors facing the construction direction of the main tunnel shall remain open; otherwise, the temporary air doors shall remain closed, and at least one of the linked air doors shall remain closed.

[0038] The jet fan on the construction side is turned on to direct the drainage of sewage.

[0039] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects:

[0040] 1. When designing ventilation schemes for tunnel-type construction, special consideration must be given to how to avoid the overlap between the path of polluted air movement and the path of fresh air introduction, which leads to the "air network short circuit" problem. This invention patent determines the structure of the work area through modeling and sets the type and location of air doors and air walls in the ventilation system, as well as the direction of the air ducts, according to the characteristic pollutant transport laws. It adopts a layout scheme such as setting rigid air walls in the ventilation ducts and cross passages of the auxiliary shaft yard where unmanned vehicles need to pass, and setting air door devices in the exit tunnels and cross passages of the auxiliary shaft yard where manned vehicles need to pass. This optimizes the airflow organization of tunnel-type ventilation in different construction scenarios in ultra-deep vertical shaft work areas, improves the pollutant ventilation control effect and suppresses the backflow of polluted air, fundamentally solves the "air network short circuit" problem, and optimizes the ventilation airflow organization and pollutant discharge effect.

[0041] 2. When conducting unidirectional or bidirectional asymmetrical multi-face construction ventilation, the asymmetrical wind pressure distribution within the underground work area roadways often drives the direction of the polluted air away from the outlet shaft (e.g., Figure 1 The movement of air in the main shaft (or around the horizontal guide tunnel-cross passage-main tunnel-cross passage, main shaft yard-horizontal guide tunnel) creates multiple annular areas, causing polluted air to stagnate in the underground work area for a long time, severely affecting sewage discharge efficiency. This invention, based on different asymmetrical multi-face construction scenarios, comprehensively considers the differences between large-mileage and small-mileage directions, and between main tunnel and horizontal guide tunnel construction. It opens or closes corresponding air doors and fans to better control and guide polluted air to less affected tunnels for discharge, optimizing the tunnel-style ventilation airflow organization in different construction scenarios of ultra-deep vertical shaft work areas and improving sewage discharge efficiency in the underground work area. Attached Figure Description

[0042] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0043] Figure 1 This is a simplified schematic diagram of the underground work area layout of a certain ultra-deep tunnel shaft provided by the present invention;

[0044] Figure 2 This is a schematic diagram of the overall structure of the geometric model of the ultra-deep vertical shaft work area with dual shafts provided by the present invention;

[0045] Figure 3 This is a partial structural schematic diagram of the geometric model of the ultra-deep vertical shaft work area with dual shafts provided by the present invention;

[0046] Figure 4 This is a schematic diagram of the layout of ventilation test points in the underground working area of ​​an ultra-deep vertical shaft provided by the present invention;

[0047] Figure 5This is a schematic diagram of the geometric model of the work area when setting up air doors, as provided by the present invention.

[0048] Figure 6 This is a schematic diagram of the layout of the ventilation system in the work area provided by the present invention;

[0049] Figure 7 This is a schematic diagram of the ventilation duct structure in the work area provided by the present invention;

[0050] Figure 8 This is a plan view of the ventilation system in operation during two-way four-face construction in the work area provided by the present invention;

[0051] Figure 9 This is a plan view of the ventilation system in operation during bidirectional, dual-working-face construction in the work area, provided by the present invention.

[0052] Figure 10 This is a plan view of the ventilation system in operation during two-way, three-face construction in the work area, provided by the present invention.

[0053] Figure 11 This is a plan view of the ventilation system being activated during unidirectional double-face construction in the work area, as provided by the present invention. Detailed Implementation

[0054] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0055] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0056] Terminology Explanation:

[0057] Extra-long railway tunnels refer to railway tunnels with a length of 10,000 meters or more.

[0058] Ultra-deep shafts are defined in the "Technical Specification for Safety Construction of Ultra-deep Shafts" as having a depth exceeding 1200m, but this specification is geared towards the mining industry. This solution addresses shafts used in railway tunnel construction, where there are no specific industry standards. However, based on experience from most engineering projects, shafts reaching depths of 500 meters typically face technical challenges such as high temperature, high pressure, complex geological conditions, and high construction costs. Therefore, this embodiment considers shafts with depths exceeding 500 meters as ultra-deep shafts.

[0059] The direction of the major mileage refers to the end direction of the tunnel route, that is, the direction of the tunnel exit.

[0060] The direction of the short mileage refers to the starting direction of the tunnel route, that is, the direction of the tunnel entrance.

[0061] A ventilation method for multi-face construction in ultra-deep vertical shaft areas of extra-long railway tunnels includes the following steps:

[0062] A model is established based on the parameters of the work area. The transport of characteristic pollutants is simulated under the set boundary conditions. Based on the simulation results, the layout structure of the ventilation system in the work area is determined.

[0063] The layout and structure of the ventilation system include:

[0064] Axial flow fan units are arranged in large-section ventilation ducts connected to the horizontal guide or main tunnel roadways. The ventilation ducts are located between the auxiliary shaft and the auxiliary shaft yard, and are used to introduce fresh air from the auxiliary shaft and send it into the air duct. There are at least two jet fans, which are arranged in two transport roadways in the main shaft yard, respectively, to accelerate the sludge and discharge it through the main shaft.

[0065] The ducts are led out from the axial flow fan unit and laid along the wall of the main tunnel. After passing through the rigid wind wall, they are laid along the wall of the horizontal guide in the directions of small mileage and large mileage respectively. The main tunnel and the horizontal guide are arranged side by side.

[0066] Rigid air walls are arranged in the ventilation duct and the two cross passages closest to the ventilation duct; temporary air doors are arranged in the two cross passages closest to the ventilation duct; and interlocking air doors are arranged in the two transport roadways of the auxiliary shaft yard. The interlocking air doors include normally open air doors and normally closed air doors that are linked together, and at least one of the two air doors is kept closed.

[0067] A model is established based on the parameters of the work area. This embodiment takes a tunnel shaft work area with a depth of over 600m as an example to establish a CFD calculation model for tunnel ventilation in ultra-deep shafts. By analyzing the transport law of pollutants in tunnel ventilation in ultra-deep shaft work areas, the influence of shaft depth on the airflow distribution characteristics and sewage discharge efficiency of the underground work area of ​​shafts set up with two shafts is determined under different tunnel ventilation schemes. Finally, the ventilation scheme during construction is determined.

[0068] The plan layout structure of an ultra-deep vertical shaft construction area in a tunnel exceeding 600m in depth is as follows: Figure 1As shown, the work area has a main tunnel and a parallel pilot tunnel (parallel pilot tunnel) arranged side by side, with multiple sets of transverse passages between them. The vertical shafts are arranged in a main and auxiliary double-shaft configuration. The main shaft is located 60m to one side of the centerline of the main tunnel, with a shaft diameter of 6m; the auxiliary shaft is located 30m to the other side of the centerline of the main tunnel, with an inner diameter of 5m. Between the bottom of the main shaft and the pilot tunnel, there are transport roadways facing the greater and lesser mileage directions respectively. Each set of transport roadways contains a corresponding muck transfer yard (in this embodiment, the muck transfer yard facing the lesser mileage direction is No. 1, and the muck transfer yard facing the greater mileage direction is No. 2). The transport roadways in both directions, together with the pilot tunnel, form a circular parking area. Between the bottom of the auxiliary shaft and the main tunnel, there are also transport roadways facing the greater and lesser mileage directions respectively. A ventilation duct also connects the two sets of transport roadways. The transport roadways in both directions, together with the main tunnel, form a circular parking area. The working faces in both the greater and lesser mileage directions of the work area are excavated using the drill-and-blast method.

[0069] Considering that both the main and auxiliary shafts need to serve as construction and production channels for introducing fresh air, transporting materials, and facilitating personnel access and the transfer of slag, rather than being used solely as ventilation shafts, forced ventilation would be limited by the single-head ventilation limit, and the installation of ductwork along the auxiliary shaft would significantly impact its hoisting capacity. Therefore, this embodiment adopts a tunnel-style ventilation system. Fresh air enters the entire work area from the auxiliary shaft, while stale air is exhausted from the main shaft. Axial flow fans are installed in the ventilation ducts of the auxiliary shaft's vehicle yard area, and flexible ductwork is used to supply air to the work faces at various distances. Except for essential access routes for construction personnel and vehicles (e.g.,...) Figure 1 The L2# and L5# cross passages and the newly added cross passages, as well as the other cross passages, are all equipped with rigid wind walls to block airflow after the corresponding adjacent main tunnel sections are completed.

[0070] The geometric model of the work area was established using ANSYS SpaceClaim software, such as... Figure 2-Figure 3 As shown, the length of the tunnels in both directions of the main tunnel is set to 100m, and the length of the tunnels in both directions of the pilot tunnel is set to 130m, in order to meet the requirement that the working face of the pilot tunnel should be at least 30m ahead of the working face of the main tunnel in the same direction. The axial flow fan in the model is simplified to a cylinder and meshed.

[0071] Solution parameter settings. The ventilation calculation model uses a pressure-based transient solver, and the SIMPLE algorithm is selected to solve the pressure coupling equations. A Realizable k-ε two-equation model is used as the turbulence model. Gravity is enabled, and the Z-direction value is set to -9.8 m / s². 2 .

[0072] Characteristic pollutant transport simulation. CO in the blasting fumes from the working face was selected as the characteristic pollutant in the shaft working area. The transport law of pollutants during roadway ventilation in the underground working area was analyzed by observing the changes in CO concentration at different ventilation times after the blast. A component transport model was activated, setting two components: air and carbon monoxide (CO), both of which were considered incompressible ideal gases. The blasting distance L and the initial CO concentration c0 in the blasting space after each working face blast were calculated using the following formulas.

[0073]

[0074] In the formula, m G b is the amount of explosive used in a single blast, in kg; b is the amount of harmful gas produced by 1 kg of explosive (converted to CO), in m. 3 / kg, based on experience, b is usually taken as 0.04m 3 / kg; S is the cross-sectional area of ​​the tunnel excavation, m² 2 Based on the actual engineering situation, S = 50.7m. 2 .

[0075] Given the complex surrounding rock conditions within the construction section, it is necessary to adopt either full-face excavation or bench excavation methods depending on the specific rock conditions. In this embodiment, the average single blasting excavation distance at the tunneling face is 1.5m, and the explosive consumption ratio is 1.1kg / m. 3 For example, through calculation, the average amount of explosive used in a single blast at the tunneling face is m. G The explosive charge weighed 83.7 kg. The distance L from which the blast fumes were thrown after the explosion was 31.7 m. The initial CO concentration within the blast fumes throwing area was 2110 mg / m³. 3 This translates to a mass fraction of 1.633 × 10⁻⁶. -3 According to current regulations, the permissible concentration of CO in tunnels must not exceed 30 mg / m³. 3 Based on the requirements, the CO concentration in the underground working area of ​​the ultra-deep vertical shaft was calculated to be 2.32 × 10⁻⁶. -5 .

[0076] Boundary Condition Setting. The auxiliary shaft opening is selected as the model's inlet boundary, and the main shaft opening as the model's outlet boundary. In actual engineering, the main and auxiliary shaft openings are connected to the external environment. Since both main and auxiliary shaft openings are located in the same ground work area, the elevation and temperature differences between the main and auxiliary shaft openings are negligible. Before the shaft work area is connected to adjacent work areas, it is difficult to form a stable, continuous, and effective natural ventilation flow within the shaft and underground work area. The airflow in the underground work area is only driven by forced ventilation from mechanical ventilation equipment. Therefore, the main and auxiliary shaft openings are set as pressure outlet boundary conditions and pressure inlet boundary conditions, respectively. The "operating pressure" of the numerical model is set to the theoretical atmospheric pressure of 80267 Pa based on the elevation of the main and auxiliary shaft openings (i.e., 1900.25 m), and the gauge pressure reference value in the wellhead pressure boundary condition is set to 0. The "operating density" value in the simulation is set to 0.

[0077] The ventilation function of an axial flow fan is simulated using the momentum source term method. It is assumed that when an axial flow fan, matched with parallel ducts, supplies air to two working faces, the theoretical maximum ventilation volume of the axial flow fan reaches 3991 m³ / h. 3 / min. The axial force S per unit volume of the axial flow fan is calculated using the following formula: a 148.5 N / m 3 .

[0078]

[0079] In the formula, S a Force per unit volume in the axial direction, N / m 3 ; v ρ is the air velocity (m / s) when a given axial flow rate passes through the ventilation fan; ρ is the air density (kg / m³). 3 ; l represents the length of the ventilation fan, in meters.

[0080] All walls are defined as non-slip solid walls ignoring thermal boundaries, using the standard wall function method. No roughness height is specified for the walls of axial flow fans and ventilation ducts. The roughness height for the walls of shafts, tunnel arches, sidewalls, floor slabs, and rigid ventilation walls is set to 0.09m.

[0081] Numerical model verification. Ventilation field tests were conducted to obtain the data required for the simulation. The test scenario was a ventilation scenario during rock drilling operations in the pilot tunnel at a lower mileage direction during an unconventional construction period. During the test, underground axial flow fans supplied air to the intersection area of ​​the circular yard at a higher mileage direction. Simultaneously, temporary local fans were installed in the connecting passage, connected to temporary ventilation ducts with a diameter of 0.8m, supplying air to the working face of the test tunnel. The temporary ducts were 25m away from the working face. Twenty test sections were set up for the on-site ventilation velocity test, with the measuring points arranged as follows: Figure 4As shown, a verification model was established based on the actual on-site measurement scenario. The ventilation momentum of the temporary local fan, combined with the average wind speed of 12.8 m / s obtained from the on-site measurement of the temporary ventilation duct outlet, was adjusted and set to 167 N / m. 3 This ensures the consistency of the initial airflow conditions at the duct outlet in the test tunnel within the numerical model of the test scenario. The initial space temperature, combined with the temperature of the fresh air introduced from the outside and the average temperature of the tunnel measured on-site, was set to 25℃.

[0082] By comparing the simulation results with the measured results, a complex mixed flow regime exists in the area between the duct outlet and the tunneling face. The flow velocity varies significantly between measuring points along the same measuring line, with the simulated values ​​generally slightly higher than the measured values. The trends of both are largely consistent. The results along the left and middle measuring lines show good correlation, but the right measuring line shows a larger error, within 0.5 m / s. This error in the right measuring line is mainly due to the ideal simplification of the spatial structure and layout of construction machinery and equipment near the working face in the model, and the neglect of the impact of air leakage from the flexible ducts on site. This leads to a difference between the measured ventilation conditions and the ideal ventilation conditions in the test scenario model. After the airflow reaches 40m from the working face, the wind velocity becomes relatively stable, generally showing the order of middle measuring line > right measuring line > left measuring line. The error between the simulated and measured values ​​is small, and the correlation between the two is good. Overall, the simulation results of the test scenario model are in good agreement with the ventilation and airflow variation patterns in the underground work area of ​​the ultra-deep vertical shaft. The turbulence mathematical model selected for the ventilation calculation model is reliable, the boundary conditions are set reasonably, and the numerical simulation results can well demonstrate the changes in the ventilation flow field in the ultra-deep vertical shaft work area.

[0083] Based on the model validation results, this embodiment adopts the following approach: Figures 5-6 The ventilation system layout shown is illustrated in the following diagram. Specifically, the structure of the work area is as follows:

[0084] There are multiple sets of transverse passages between the parallel main tunnel and the horizontal guide tunnel. In this embodiment, they are set as transverse passages L1#-L7#, where L1#, L6# and L7# are passages to be constructed, and the existing transverse passages are L2#-L5#.

[0085] The cross passages can also be divided according to the construction mileage direction. Cross passages along the smaller mileage direction, with the ventilation duct as the boundary, are designated X01, X02...Xn, and those along the larger mileage direction are designated D01, D02...Dn. In this embodiment, the existing cross passages L2#-L5# are named cross passage X02, cross passage X01, cross passage D01, and cross passage D02 respectively, and the cross passage to be constructed, L6#, is named cross passage D03.

[0086] The construction direction of the main tunnel and the pilot tunnel is divided by the ventilation duct, with one side being the direction of the lower mileage and the other side being the direction of the higher mileage.

[0087] The bottom of the main shaft and the horizontal guide have transport roadways facing the large mileage and small mileage directions respectively. Each set of transport roadways is equipped with a corresponding slag transfer yard (in this embodiment, the slag transfer yard facing the small mileage direction is No. 1, and the slag transfer yard facing the large mileage direction is No. 2). The transport roadways in the two directions and the horizontal guide form a ring-shaped main shaft yard, and the main shaft yard is connected to the main shaft.

[0088] The bottom of the auxiliary shaft is connected to the main tunnel by transport tunnels facing the high mileage and low mileage directions respectively. There is also a ventilation tunnel between the two sets of transport tunnels. The transport tunnels in the two directions form a ring-shaped auxiliary shaft yard with the main tunnel, and the auxiliary shaft yard is connected to the auxiliary shaft.

[0089] Based on the structure of the work area and the pollutant transport patterns described above, the ventilation system layout proposed in this embodiment is as follows:

[0090] Axial flow fan units are arranged in the ventilation duct to introduce fresh air from the auxiliary shaft and send it into the air duct; at least two jet fan units are arranged in two transport roadways in the main shaft yard to accelerate the delivery of sludge into the main shaft for discharge.

[0091] After being led out by the axial flow fan unit, the duct is laid along the main tunnel wall in the direction of the small mileage and the large mileage respectively. After passing through the rigid wind wall, it is laid along the flat guide wall in the direction of the small mileage and the large mileage respectively.

[0092] There are three sets of rigid ventilation walls, arranged in the ventilation duct and the two cross passages closest to the ventilation duct; there are two sets of temporary ventilation doors, arranged in the two cross passages closest to the ventilation duct; there are two sets of interlocking ventilation doors, arranged in the two transport roadways of the auxiliary shaft yard. The interlocking ventilation doors include normally open ventilation doors and normally closed ventilation doors that are linked together. In each set of ventilation doors, the ventilation door closer to the main tunnel is normally closed, and the other ventilation door is normally open. At least one of the two ventilation doors is kept closed.

[0093] That is, rigid air walls are arranged in cross passages X01, D01 and ventilation ducts, temporary air dampers are arranged in cross passages X02 and D02, and at least two sets of axial flow fans are used to provide fresh air for the small mileage and large mileage directions respectively.

[0094] The longitudinal structure of the auxiliary well is as follows Figure 7 As shown, the bottom of the auxiliary shaft is the underground gate tunnel, which is connected to the shaft of the auxiliary shaft. The space above the gate tunnel is connected to the ventilation duct through an inclined shaft at a certain angle. The cross-sectional diameter or width of the inclined part is smaller than that of the ventilation duct. In this embodiment, the ventilation duct of the inclined part is named the small cross-sectional ventilation duct, and the ventilation duct of the horizontal part is named the large cross-sectional ventilation duct. The axial flow fan is arranged in the large cross-sectional ventilation duct.

[0095] Considering the structural design of the work area, the actual project took into account the use of a tunnel-style ventilation method during normal construction. Therefore, in the early design and excavation phase, a channel was excavated at an angle below the auxiliary shaft to connect to the tunnel's pilot tunnel or main tunnel (i.e., a ventilation duct). An axial flow fan was placed directly in the ventilation duct to draw fresh air into the underground work area. This avoids the impact of noise and space occupation during the axial flow fan's ducting process on the originally complex transportation and construction process route arrangement below the auxiliary shaft. Furthermore, from a ventilation flow perspective, placing the axial flow fan in the ventilation duct is more energy-efficient and economical than placing it directly in the auxiliary shaft.

[0096] The ventilation duct is made of PVC flexible double-resistant soft duct. One end is connected to the air outlet of the axial flow fan, and the other end extends through the construction roadway to the working face near the main tunnel or the horizontal guide in the direction of the mileage. Alternatively, in a suitable location, the ventilation duct branch is connected by a "Y" or "T" shaped parallel structure and extends through the two horizontal channels closest to the ventilation duct to the working face near the horizontal guide or the main tunnel in the direction of the mileage.

[0097] In this embodiment, a suitable location typically refers to the middle area between the outlet side of the axial flow fan (i.e., the side with the duct interface) and the connecting passage (cross passage) that requires passage for people and vehicles in both directions of length and width; the connection of each section of ventilation duct adopts slot connection, bolt connection or flange connection according to the construction situation.

[0098] Rigid ventilation walls are installed at the large-section ventilation ducts in the auxiliary shaft yard and in the middle of the cross passages where vehicles and personnel do not need to pass after the completion of the corresponding adjacent main tunnel section, namely cross passages X01 and D01. The rigid ventilation walls installed at the ventilation ducts in the auxiliary shaft yard are connected by axial flow fans, and the rigid ventilation walls installed in the middle of the two connecting passages (cross passages X01 and D01) closest to the ventilation ducts are connected by ventilation ducts. The rigid ventilation walls are made of rigid materials such as galvanized iron sheets. The rigid ventilation walls and ventilation ducts are connected and sealed with rigid flanges.

[0099] The interlocking airlock is a pressureless airlock, consisting of at least two interlocking airlocks, spaced approximately 5-10 meters apart. The other airlock can only open when one is closed. Each airlock operates on a pressure balance principle, using a linkage structure and limiters fixed to the door frame to achieve synchronous opening and closing of the two doors in opposite directions. The pressureless airlock can be fully automatically controlled using infrared sensors or semi-automatically controlled by push-buttons. Within each group of airlocks, the airlock closer to the tunneling roadway is normally closed (pressureless), while the other is normally open.

[0100] Temporary airlocks are installed in two transverse passages (X02 and D02) connecting the main shaft yard and the auxiliary shaft yard in both directions. Each temporary airlock consists of at least one button-operated semi-automatic door. Based on the principle of pressure balance, each door uses a linkage structure and a limit switch fixed to the door frame to achieve synchronous opening and closing of the two doors in opposite directions. Temporary airlocks are located in the transverse passages between the horizontal guide tunnel and the main tunnel where personnel and construction vehicles need to pass; under normal conditions, the temporary airlocks are in a normally open state, and commercially available mature airlock products can be selected.

[0101] The jet fans are installed near the entrance roadway of the main shaft yard (slag transfer yard), and are installed close to one side of the cavern wall according to the spatial structure of the main shaft yard (slag transfer yard).

[0102] Multi-face construction scenarios include bidirectional symmetrical construction scenarios, bidirectional asymmetrical construction scenarios, and unidirectional asymmetrical construction scenarios.

[0103] A bidirectional symmetrical construction scenario refers to a multi-face construction scenario in which symmetrical working faces are simultaneously constructed in the direction of large or small mileage, including a bidirectional four-face construction scenario. Figure 8 ) and two-way, two-face construction scenarios ( Figure 9 Bidirectional asymmetrical construction scenarios refer to construction scenarios where work is carried out simultaneously in both directions of mileage, but the working faces are not symmetrical on the pilot tunnel or main tunnel line; these are mainly bidirectional three-working-face construction scenarios. Unidirectional asymmetrical construction scenarios refer to multi-working-face construction scenarios where work is carried out only in one direction of mileage, with two working faces; these are mainly unidirectional two-working-face construction scenarios.

[0104] Two-way symmetrical multi-face construction scenarios include two-way four-face construction scenarios, such as... Figure 8 As shown, tunnel excavation is carried out simultaneously in both the main tunnel and the pilot tunnel, moving towards both the large and small mileage directions; the two-way, two-working-face construction scenario is as follows. Figure 9 The diagram illustrates a scenario where tunnel excavation is being carried out simultaneously in both the main tunnel and pilot tunnel directions (in this embodiment, excavation is being carried out simultaneously in both directions within the pilot tunnel). When the ultra-deep vertical shaft work area is undergoing bidirectional symmetrical multi-face construction, two axial flow fans are activated to supply air to the working faces via ventilation ducts. During bidirectional four-face construction, the temporary air doors of the connecting passages on both sides remain open. During bidirectional two-face construction, if a working face exists in the main tunnel, the temporary air door facing the main tunnel construction direction remains open; otherwise, the temporary air door remains closed. In the auxiliary shaft yard, the air door on the side closer to the construction roadway in the exit roadways is kept closed, while the other air door is open.

[0105] When passing through the auxiliary shaft yard, when passing through the normally closed air door in the linkage air door, the normally open air door is closed first, and then the normally closed air door is opened; after passing through the normally closed air door, the normally closed air door is reset and closed, and the normally open air door is opened simultaneously.

[0106] The direction of the interlocking air doors is not restricted. For example, when construction personnel or vehicles in the auxiliary shaft yard need to temporarily pass through to enter the construction roadway, they first pass through the normally open pressureless air door, and then use the fully automatic infrared sensor or semi-automatic button between the two air doors to open the normally closed air door. At the same time, the normally open air door closes in conjunction with the interlocking air door, allowing them to enter the tunneling roadway through the normally closed air door. After the construction personnel or vehicles pass through the normally closed air door, they reset the pressureless air door using the fully automatic infrared sensor or semi-automatic button outside the normally closed air door, thus closing the normally closed air door and opening the normally open air door in conjunction with the interlocking air door. The temporary air door is in the normally open state. The opposing working faces of the horizontal pilot tunnel or main tunnel should maintain a relatively consistent tunneling progress as much as possible to maintain a relatively balanced air pressure. When there is a large difference in the tunneling progress of the opposing working faces, the jet fan (at a lower power setting) at the entrance of the muck yard on the side with faster construction progress should be turned on to appropriately divert and balance the airflow and air pressure.

[0107] Two-way asymmetric multi-face construction scenarios mainly include two-way three-face construction scenarios, such as... Figure 10 As shown, tunneling proceeds simultaneously in both the high and low mileage directions in the pilot tunnel, while tunneling proceeds in either the high or low mileage direction in the main tunnel. When conducting bidirectional asymmetrical multi-face construction, the corresponding axial flow fans on the construction side are activated (generally, an axial flow fan unit has at least two fans, providing fresh air for construction in both the high and low mileage directions respectively; more may be used in special cases; the specific number is not limited here, but only represents the setup for most situations), supplying air to the working face via ventilation ducts. The temporary air doors of the connecting passages in the main tunnel construction direction remain open, while the temporary air doors of the connecting passages in the non-construction direction remain closed. In the auxiliary shaft yard, the air door on the side closer to the construction passage in the unpressurized air doors of the exit roadways on both sides remains closed, while the other air door remains open.

[0108] When passing through the auxiliary shaft yard, the normally closed air door is activated first, then the normally open air door is activated again. After passing through the normally closed air door, the normally closed air door is reset and closed, while the normally open air door is activated simultaneously. There are no restrictions on the direction of passage. For example, when construction personnel or vehicles in the auxiliary shaft yard need to temporarily enter the construction roadway, they first pass through the normally open pressureless air door, then open the normally closed air door using the fully automatic infrared sensor or semi-automatic button between the two air doors. The normally open air door closes simultaneously, allowing passage into the tunneling roadway. After passing through the normally closed air door, the pressureless air door is reset using the fully automatic infrared sensor or semi-automatic button outside the normally closed air door, closing it and activating the normally open air door. The temporary air door of the connecting passage on one side of the single working face is closed by controlling the button, and the jet fan at the entrance of the slag yard on the construction side is activated for directional drainage.

[0109] Unidirectional asymmetric multi-face construction scenarios are mainly unidirectional double-face construction scenarios, such as... Figure 11As shown, excavation proceeds in either the main tunnel or the pilot tunnel towards a larger or smaller mileage. When unidirectional asymmetrical multi-face construction is carried out in the ultra-deep vertical shaft work area, the corresponding axial flow fan on the construction side is turned on, supplying air to the working face through the ventilation duct. The temporary air doors of the connecting passages in the construction direction remain open, while the temporary air doors of the connecting passages in the non-construction direction remain closed. Among the unpressurized air doors of the exit roadways on both sides of the auxiliary shaft yard, the air door on the side closer to the construction roadway remains closed, while the other air door remains open.

[0110] When passing through the auxiliary shaft yard, the normally closed air door is activated first, then the normally open air door is activated again. After passing through the normally closed air door, the normally closed air door is reset and closed, while the normally open air door is activated simultaneously. There are no restrictions on the direction of passage. For example, when construction personnel or vehicles in the auxiliary shaft yard need to temporarily enter the construction roadway, they first pass through the normally open pressureless air door, then open the normally closed air door using the fully automatic infrared sensor or semi-automatic button between the two air doors. The normally open air door closes, allowing passage into the tunneling roadway. After passing through the normally closed air door, the pressureless air door is reset using the fully automatic infrared sensor or semi-automatic button outside the normally closed air door, closing it and activating the normally open air door. Temporary air doors in non-construction side connecting passages are closed using control buttons, and the jet fan at the construction side slag yard entrance is activated for directional drainage.

[0111] By installing pressureless air doors with linkage control in the exit roadways on both sides of the auxiliary shaft yard, the circulation and return path of sewage air in multiple working faces in the underground work area can be effectively blocked, thereby fundamentally suppressing the problem of short circuit in the ventilation network of the underground work area and improving the ventilation and sewage discharge efficiency of the underground work area.

[0112] In addition to the multi-face construction scenarios mentioned above, there are also single-face construction scenarios in actual projects. In a single-face construction scenario, the axial flow fan corresponding to the construction side is turned on, and fresh air from the auxiliary shaft is supplied to the working face through the ventilation duct.

[0113] During construction, if there is a working face in the main tunnel, the temporary air doors facing the construction direction of the main tunnel shall remain open; otherwise, the temporary air doors shall remain closed, and at least one of the linked air doors shall remain closed.

[0114] The jet fan on the construction side is turned on to direct the drainage of sewage.

[0115] Furthermore, by setting up and activating temporary air dampers and jet fans in a timely manner, the problem of stagnant polluted air caused by uneven ventilation pressure distribution in the asymmetrical construction scenarios of bidirectional and unidirectional ultra-deep vertical shaft work areas can be optimized to a certain extent, thereby improving the ventilation and sewage discharge effect in the underground work areas.

[0116] Different types of air doors can improve the ventilation effect of the work area by setting their location and adopting different opening and closing states in different construction scenarios. According to relevant simulation experiments, when a roadway ventilation scheme without air doors is adopted, some of the polluted air in the underground work area will flow back to the axial flow fan to participate in recirculation and mix with the fresh air outside the shaft, resulting in "ventilation short circuit" and poor ventilation quality. However, after setting air doors in the exit roadways on both sides of the auxiliary shaft to block the backflow path, the pollutant discharge efficiency of the underground work area is significantly improved.

[0117] Through relevant simulation experiments, when a tunnel ventilation scheme without air doors is adopted, as the depth of the shaft increases, the air intake flow of the underground axial flow fan remains basically unchanged. However, due to the increase in frictional resistance along the shaft and vertical static pressure difference, the proportion of fresh air flow outside the shaft decreases, while the proportion of sewage air flow underground gradually increases, resulting in a decrease in sewage discharge efficiency in the underground work area.

[0118] Through relevant simulation experiments, it was found that when the tunnel ventilation scheme with dampers is adopted, as the depth of the shaft increases, the flow rate of the underground axial flow fan decreases, the ventilation velocity in the underground work area decreases, and the sewage discharge efficiency gradually decreases, but it is still higher than the sewage discharge efficiency without dampers.

[0119] Therefore, by using the above-mentioned ventilation construction methods, the necessary fans, ducts, and dampers can be arranged at specific locations in the underground work area of ​​ultra-deep vertical shafts. This improves the tunnel-like ventilation effect in bidirectional and unidirectional multi-face construction scenarios in ultra-deep vertical shaft underground work areas, suppresses the backflow of polluted air, fundamentally solves the "short circuit of the ventilation network" problem, optimizes the ventilation airflow organization and pollutant discharge effect, and provides a reference for the formulation of ventilation control strategies for multi-face construction sites in ultra-deep vertical shaft underground work areas of extra-long railway tunnels and similar projects.

[0120] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A ventilation method for multi-face construction in ultra-deep vertical shaft areas of extra-long railway tunnels, characterized in that: Includes the following steps: A model is established based on the parameters of the work area. The transport of characteristic pollutants is simulated under the set boundary conditions. Based on the simulation results, the layout structure of the ventilation system in the work area is determined. Switch the corresponding damper switches in the ventilation system according to different work site construction scenarios; The layout structure of the ventilation system includes: Axial flow fans are installed in ventilation ducts located between the auxiliary shaft and the auxiliary shaft yard; jet fans are installed in the transport roadways of the main shaft yard. The ducts are led out from the axial flow fan unit and laid along the wall of the main tunnel. After passing through the rigid wind wall, the ducts are laid along the wall of the horizontal guide in the direction of small mileage and large mileage respectively. The main tunnel and the horizontal guide are arranged side by side. Rigid air walls are arranged in the ventilation duct and the two cross passages closest to the ventilation duct; temporary air doors are arranged in the two cross passages that are next closest to the ventilation duct; and linkage air doors are arranged in the two transport roadways of the auxiliary shaft yard. Each set of linkage air doors includes two linkage-controlled air doors. During operation, at least one of the two air doors remains closed. Depending on the different construction work scene and actual passage requirements, switch the corresponding air damper to open or close, activate the axial flow fan to introduce fresh air to the outside through the ventilation duct and the auxiliary shaft, and send the fresh air into the work face through the air duct. Turn the jet fan on or off as needed to drive the generated sludge through the main shaft to be discharged.

2. The ventilation method for multi-face construction in an ultra-deep vertical shaft area of ​​an extra-long railway tunnel as described in claim 1, characterized in that: The model established based on the work area parameters includes the following steps: The main tunnel and pilot tunnel are set up side by side, with multiple sets of cross passages between them. With the ventilation duct as the boundary, the cross passages along the small mileage direction are X01, X02...Xn, and the cross passages along the large mileage direction are D01, D02...Dn. The bottom of the main shaft and the horizontal guide have transport roadways facing the large mileage and small mileage directions respectively. Each set of transport roadways is equipped with a corresponding slag transfer yard. The two transport roadways and the horizontal guide form a ring-shaped main shaft yard, which is connected to the main shaft. The bottom of the auxiliary shaft is connected to the main tunnel by transport tunnels facing the high mileage and low mileage directions respectively. A ventilation duct is also provided between the two sets of transport tunnels. The transport tunnels in the two directions form a ring-shaped auxiliary shaft yard with the main tunnel, and the auxiliary shaft yard is connected to the auxiliary shaft.

3. The ventilation method for multi-face construction in an ultra-deep vertical shaft construction area of ​​an extra-long railway tunnel as described in claim 1, characterized in that: In each set of interconnected air doors, the air door closest to the main tunnel is normally closed, and the other air door is normally open.

4. The ventilation method for multi-face construction in an ultra-deep vertical shaft area of ​​an extra-long railway tunnel as described in claim 1, characterized in that: The rigid air wall is made of rigid material and is sealed to the air duct. The rigid air wall is used to block gas from flowing through the channel from the space outside the air duct.

5. The ventilation method for multi-face construction in an ultra-deep vertical shaft construction area of ​​an extra-long railway tunnel as described in claim 1, characterized in that: Multi-face construction scenarios include bidirectional four-face construction scenarios. In bidirectional four-face construction scenarios, the axial flow fan unit is started, and fresh air from the auxiliary shaft is supplied to the working face through the air duct. During construction, temporary air doors shall remain open, and at least one air door in each set of linked air doors shall remain closed. When the difference in excavation progress between the working faces of the pilot tunnel or the main tunnel exceeds the set range, the jet fan at the entrance of the slag dump on the side with faster construction progress is turned on to balance the airflow and air pressure by diverting the sewage air.

6. The ventilation method for multi-face construction in an ultra-deep vertical shaft construction area of ​​an extra-long railway tunnel as described in claim 1, characterized in that: Multi-face construction scenarios include bidirectional double-face construction scenarios. In bidirectional double-face construction scenarios, the axial flow fan unit is started, and fresh air from the auxiliary shaft is supplied to the working face through the air duct. During construction, if there is a working face in the main tunnel, the temporary air doors facing the construction direction of the main tunnel shall remain open; otherwise, the temporary air doors shall remain closed. In each set of linked air doors, at least one air door shall remain closed. When the difference in excavation progress between the working faces of the pilot tunnel or the main tunnel exceeds the set range, the jet fan at the entrance of the slag dump on the side with faster construction progress is turned on to balance the airflow and air pressure by diverting the sewage air.

7. The ventilation method for multi-face construction in an ultra-deep vertical shaft construction area of ​​an extra-long railway tunnel as described in claim 1, characterized in that: Multi-face construction scenarios also include bidirectional three-face construction scenarios. In bidirectional three-face construction scenarios, the axial flow fan unit is started, and fresh air from the auxiliary shaft is supplied to the working face through the air duct. During construction, if there is a working face in the main tunnel, the temporary air doors facing the construction direction of the main tunnel shall remain open; otherwise, the temporary air doors shall remain closed. In each set of linked air doors, at least one air door shall remain closed. The jet fan on one side of the double-working-face construction is turned on to direct the drainage of sewage.

8. The ventilation method for multi-face construction in an ultra-deep vertical shaft construction area of ​​an extra-long railway tunnel as described in claim 1, characterized in that: Multi-face construction scenarios also include unidirectional double-face construction scenarios. In the unidirectional double-face construction scenario, the axial flow fan corresponding to the construction side is turned on, and fresh air from the auxiliary shaft is supplied to the working face through the air duct. During construction, temporary air doors in the direction of construction shall remain open, while temporary air doors in the direction of non-construction shall be closed. Among the linked air doors, at least one air door shall remain closed. The jet fan on one side of the double-working-face construction is turned on to direct the drainage of sewage.

9. A ventilation method for multi-face construction in an ultra-deep vertical shaft construction area of ​​an extra-long railway tunnel as described in claim 1, characterized in that: In addition to multi-face construction scenarios, it also has single-face construction scenarios. In the single-face construction scenario, the axial flow fan corresponding to the construction side is turned on, and fresh air from the auxiliary shaft is supplied to the working face through the air duct. During construction, if there is a working face in the main tunnel, the temporary air doors facing the construction direction of the main tunnel shall remain open; otherwise, the temporary air doors shall remain closed, and at least one of the linked air doors shall remain closed. The jet fan on the construction side is turned on to direct the drainage of sewage.

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