A highway tunnel smoke exhaust system and a method for optimizing a smoke exhaust angle

Abstract

The present application provides a highway tunnel smoke exhaust system and a smoke exhaust angle optimization method, by setting the included angle between the smoke exhaust transverse hole axis and the tunnel body axis as an acute angle, and ingeniously utilizing the dynamic characteristics of fluid at the three-way confluence node, the asymmetric arrangement of the acute angle deviating to the downstream tunnel increases the local resistance of the upstream clean air countercurrent inflow, while reducing the flow resistance of the upstream tunnel fire smoke inflow, the effective pressure difference of the smoke exhaust fan is preferentially guided to the upstream smoke side, which fundamentally cuts off the downstream air short circuit path, significantly improves the smoke capture rate and system disaster prevention reliability under fire conditions; and the fluid resistance evolution law is accurately mathematically mapped with the transverse hole length and the excavation engineering quantity, the best balance point between the smoke exhaust efficiency improvement and the increase of the civil engineering cost is automatically iterated and optimized, which effectively avoids the safety hazards caused by excessive excavation or excessive compression cost caused by single pursuit of smoke exhaust effect.

Description

Technical Field

[0001] This invention relates to the field of highway tunnel ventilation and disaster prevention technology, and in particular to a method for optimizing a highway tunnel smoke exhaust system and the smoke exhaust angle. Background Technology

[0002] Currently, smoke extraction in long highway tunnel fires generally adopts a segmented smoke extraction mode of "longitudinal ventilation + centralized exhaust through a cross passage." This mode involves setting up a cross passage in the middle of the tunnel, which, in conjunction with smoke extraction fans, concentrates and exhausts the fire smoke outside the tunnel. In existing technology, the cross passage is usually connected perpendicularly to the tunnel body (at a 90° angle). This structure has an inherent and insurmountable defect: when the smoke extraction fan is running, the suction negative pressure formed at the entrance of the cross passage acts simultaneously on the upstream smoke side and the downstream fresh air side of the tunnel. Because the downstream air inflow path is direct and the flow resistance is low, a large amount of fan power is used to extract downstream fresh air rather than effectively extracting smoke, resulting in a serious "air short-circuit" effect. The root cause is the mismatch in the path resistance of the upstream and downstream fluids flowing into the cross passage. The excessively low downstream resistance leads to an unreasonable pressure differential distribution, ultimately resulting in low smoke capture efficiency, allowing a large amount of smoke to spread downstream and expand the scope of the disaster.

[0003] To address the aforementioned issues, existing improvement solutions mostly focus on increasing the power of exhaust fans, optimizing fan start-up and shutdown logic, or increasing the number of exhaust outlets. These solutions all fall under the "incremental compensation" approach, merely compensating for performance deficiencies by increasing system investment. They fail to address the core issue of upstream and downstream flow resistance imbalance from a fundamental fluid dynamics perspective. This not only increases construction and operating costs but also provides limited improvement in exhaust efficiency. A few engineering cases have adjusted the orientation of exhaust cross passages, but these adjustments are primarily driven by adapting to terrain conditions, avoiding geological disaster zones, or reducing earthwork excavation. This represents passive structural layout optimization, with the angle selection entirely reliant on engineering experience. It fails to achieve an optimal balance between exhaust efficiency and engineering costs, making it difficult to meet the disaster prevention and safety requirements of tunnels under different working conditions.

[0004] Therefore, it is necessary to propose an optimization method for the smoke exhaust system and smoke exhaust angle of highway tunnels to solve or at least alleviate the above-mentioned defects. Summary of the Invention

[0005] The main objective of this invention is to provide a method for optimizing a smoke exhaust system and smoke exhaust angle in a highway tunnel, so as to solve the problem that existing tunnel smoke exhaust schemes cannot optimize the balance between smoke exhaust efficiency and civil engineering economy.

[0006] To achieve the above objectives, the present invention provides a method for optimizing the smoke exhaust angle of highway tunnels, comprising the following steps: S1, Obtain basic data on the vertical setting of the smoke exhaust cross passage and the tunnel body in the highway tunnel smoke exhaust system, in order to build a basic database; S2, Establish a flue gas capture rate model based on the aforementioned basic database. This is to indicate the angle between the central axis of the smoke exhaust cross passage and the central axis of the tunnel body. The influence of the proportion of fire smoke drawn into the cross passage within the tunnel; where the included angle It is an acute angle; S3, Establish an engineering cost model based on the aforementioned basic database. , to represent the included angle The impact of the construction cost of the smoke exhaust tunnel; S4, the flue gas capture rate model Perform normalization processing and compare it with the engineering cost model. Weighted coupling to construct a comprehensive benefit objective function ; S5, regarding the comprehensive benefit objective function Perform iterative optimization to obtain the angle that maximizes the overall benefit objective function. The optimal design angle for the horizontal smoke exhaust duct. .

[0007] Preferably, the junction of the upstream tunnel of the tunnel body, the downstream tunnel of the tunnel body, and the smoke exhaust cross passage forms a confluence point; The basic database includes the static pressure of the upstream tunnel at the confluence point. The static pressure of the downstream tunnel at the confluence point Static pressure at the entrance of the smoke exhaust duct The flow rate of flue gas flowing from upstream into the flue gas duct The airflow velocity from downstream into the smoke exhaust duct Density of flue gas / air mixture The length of the smoke exhaust cross passage when it is set perpendicularly to the tunnel body Cross-sectional area .

[0008] Preferably, step S2 specifically includes the following steps: S21, Based on the fluid dynamics theory of branched flow in a pipe, establish the resistance coefficient and the included angle for the inflow into the cross passage. The relationship between the correction functions; S22. Based on Bernoulli's equation and the law of conservation of mass, establish the mapping relationship between the drag coefficient flowing into the cross tunnel and the flow velocity flowing into the flue gas cross tunnel. S23, Establish the flue gas capture rate model based on the correction function relationship and the mapping relationship. .

[0009] Preferably, the flue gas capture rate model Defined as: in, The resistance coefficient of the smoke exhaust cross passage flowing into the smoke exhaust cross passage from the upstream tunnel when it is set perpendicularly to the tunnel body. When the smoke exhaust cross passage is set perpendicularly to the tunnel body, the resistance coefficient of the downstream tunnel flowing into the smoke exhaust cross passage is determined. An empirical coefficient is used to correct the angle of the upstream tunnel. An empirical coefficient is used to correct the angle of the downstream tunnel.

[0010] Preferably, step S3 specifically includes the following steps: S31, Determine the included angle based on spatial geometric projection relationships. The actual length of the horizontal tunnel below ; in, ; S32, based on the actual transverse tunnel length Determine the actual excavation volume ; in, ; S33, based on the actual transverse tunnel length and the actual excavation volume Establish an engineering cost model ; in, This indicates the excavation volume when the smoke exhaust cross passage is set vertically between the tunnel body and the tunnel body.

[0011] Preferably, in step S4, the flue gas capture rate model is... pass After normalization, the normalized flue gas capture rate is obtained. , to represent the performance improvement factor relative to the vertical design; where, The smoke capture rate is the result of a vertically positioned smoke exhaust cross passage between the cross passage and the tunnel body.

[0012] Preferably, the comprehensive benefit objective function Defined as: in, This is a weighting coefficient for the flue gas capture rate. For cost control, the weighting coefficient is... + =1, > .

[0013] Preferably, step S5 specifically includes the following steps: S51, determine the weighting coefficient of the flue gas capture rate. The weighting coefficient of the aforementioned cost control The included angle The possible values ​​of ; S52, the weighting coefficient of the determined flue gas capture rate. The weighting coefficient of the aforementioned cost control The included angle Substituting the value of into the comprehensive benefit objective function In order to obtain and record Discrete values; S53, Adjust the included angle The value of is determined, and steps S51-S52 are repeated iteratively until the solution is obtained. The value is iterated through all values ​​within its preset range; where, =50°, 51°...74°, 75°; S54, based on various Discrete value plotting Curve, and observe In the curve The included angle corresponding to the maximum value The optimal design angle for the horizontal smoke exhaust duct. .

[0014] Preferably, the weighting coefficient of the flue gas capture rate The value range is 0.6≤ ≤0.9, the weighting coefficient of the cost control The value range is 0.1≤ ≤0.4.

[0015] This application also provides a highway tunnel smoke exhaust system, applied to the method for optimizing the smoke exhaust angle of a highway tunnel as described above, comprising a tunnel body and a smoke exhaust cross passage, wherein the smoke exhaust cross passage is inclined and one end is connected to the tunnel body; wherein... The tunnel body includes an internally connected upstream tunnel and a downstream tunnel, and the smoke exhaust cross passage forms an angle with the downstream tunnel. And the included angle It is an acute angle.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a smoke extraction system for highway tunnels and a method for optimizing the smoke extraction angle, which optimizes the angle between the central axis of the smoke extraction cross passage and the central axis of the tunnel body. By setting the angle as acute, the system cleverly utilizes the dynamic characteristics of fluids at the T-junction junction. The asymmetrical arrangement of the acute angle towards the downstream tunnel asymmetrically increases the local resistance to the downstream clean air flowing in against the current, while simultaneously reducing the flow resistance to the upstream fire smoke flowing in with the current. This prioritizes guiding the effective pressure difference of the exhaust fan to the upstream smoke side, fundamentally cutting off the downstream air short-circuit path and significantly improving the smoke capture rate and system disaster prevention reliability under fire conditions. Furthermore, the system precisely mathematically maps the evolution of fluid resistance with the length of the cross passage and the amount of excavation work, making the angle... The mechanism of the two-way impact of smoke extraction efficiency and construction cost is quantified and calculable. It automatically iterates to find the best balance between improving smoke extraction efficiency and increasing civil engineering costs, effectively avoiding the safety hazards caused by excessive excavation or excessive cost reduction due to the pursuit of smoke extraction effect. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a process flow diagram of the overall optimization method in one embodiment of the present invention; Figure 2 This is a schematic diagram of a highway tunnel smoke exhaust system according to an embodiment of the present invention; Figure 3 A comparison diagram of the smoke extraction effects of a traditional horizontal smoke extraction system and a smoke extraction system with the optimized angle in this application; Figure 4 This is a horizontal flow field diagram at a height of 3m above the road surface of a conventional cross-tunnel smoke exhaust system according to an embodiment of the present invention. Figure 5 This is a diagram of the smoke flow field at a height of 3m above the road surface of the smoke exhaust system after optimizing the included angle in one embodiment of the present invention.

[0019] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0020] Explanation of icon numbers: 10. Tunnel body; 110. Upstream tunnel; 120. Downstream tunnel; 20. Smoke exhaust cross passage. Detailed Implementation

[0021] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0024] Please see the appendix Figure 1 ~Appendix Figure 5 An embodiment of the present invention provides a method for optimizing the smoke exhaust angle of a highway tunnel, comprising the following steps: S1, acquire basic data on the vertical arrangement of the smoke exhaust cross passage 20 and the tunnel body 10 in the highway tunnel smoke exhaust system to construct a basic database; vertical arrangement ( =90°) is the traditional benchmark state by default in the current specifications. Its flow field pressure distribution, geometric dimensions and excavation volume have clear engineering measurability or can be directly extracted from design drawings. As the "zero reference system" for optimization iteration, this state can calibrate the initial resistance coefficient and benchmark cost. Thus, the established basic database can provide unified and accurate benchmark parameters for all subsequent modeling and calculations, eliminate model errors caused by inconsistent data sources, and ensure the reliability of optimization results. In detail, the intersection of the upstream tunnel 110 of the tunnel body 10, the downstream tunnel 120 of the tunnel body 10 and the smoke exhaust cross tunnel 20 forms a confluence point. The basic database includes the static pressure of the upstream tunnel 110 at the confluence point. The static pressure of downstream tunnel 120 at the confluence point Static pressure at the inlet of the smoke exhaust cross tunnel 20 The flow rate of flue gas flowing from upstream into the exhaust cross passage 20 is... The airflow velocity from downstream into the smoke exhaust transverse tunnel 20 Density of flue gas / air mixture The length of the smoke exhaust cross passage 20 when it is perpendicular to the tunnel body 10 Cross-sectional area All of the above data can be obtained from tunnel design drawings or relevant design specifications.

[0025] S2, Establish a flue gas capture rate model based on the aforementioned basic database. To indicate the angle between the central axis of the smoke exhaust cross tunnel 20 and the central axis of the tunnel body 10. The influence of the proportion of fire smoke drawn into the cross passage within the tunnel; where the included angle The angle is acute; it is understandable that the flow at the smoke exhaust cross passage 20 is essentially a three-way confluence problem: when the cross passage connects to the main tunnel at different angles, the turning angles of the upstream smoke and downstream air are different, resulting in significant differences in the intensity of flow separation vortices and energy loss. This application utilizes this asymmetric characteristic to reduce... By actively reducing upstream flue gas resistance and increasing downstream air resistance, the system prioritizes the extraction of flue gas. Based on the essence of fluid mechanics, it quantifies the asymmetric impact of the tilt angle on the resistance of upstream and downstream fluid inflow, establishes a precise mathematical mapping relationship between the angle and the smoke extraction efficiency, and solves the problem of not being able to quantitatively assess the impact of the angle on the smoke extraction effect in traditional designs.

[0026] S3, Establish an engineering cost model based on the aforementioned basic database. , to represent the included angle The impact on the construction cost of the smoke exhaust cross tunnel 20: It should be understood that the civil engineering construction cost of the smoke exhaust cross tunnel 20 is directly proportional to the excavation volume, which is determined by the length and cross-sectional area of ​​the cross tunnel. When the cross tunnel... When tilted downstream, its actual length is the length of the hypotenuse, and so on. Decreasing the angle of inclination leads to an increase in excavation volume and cost. This quantifies the impact of the inclination angle on the excavation volume of the smoke exhaust tunnel 20, establishes a mathematical relationship between the angle and the project cost, and provides economic constraints for subsequent comprehensive benefit optimization.

[0027] S4, the flue gas capture rate model Perform normalization processing and compare it with the engineering cost model. Weighted coupling to construct a comprehensive benefit objective function It's worth noting that the flue gas capture rate is measured as a percentage, while the engineering cost model uses a dimensionless ratio; their different dimensions prevent direct weighting. Normalization can... This is transformed into a performance improvement factor relative to traditional designs, achieving dimensional unification and enabling weighted coupling with dimensionless engineering cost models. By setting reasonable weight coefficients, an objective function of "comprehensive benefit = safety gains + cost increment" is constructed. Maximizing this function yields the optimal balance between safety and economy, achieving a quantitative balance between safety and economy.

[0028] S5, regarding the comprehensive benefit objective function Perform iterative optimization to obtain the angle that maximizes the overall benefit objective function. The optimal design angle for the smoke exhaust cross passage 20. Comprehensive benefit objective function It is a unimodal function, with a unique maximum point within a preset interval. This is achieved by iterating through all the peaks within the interval. Value, calculate the corresponding The optimal angle can be determined by solving the comprehensive benefit objective function using numerical iteration methods, transforming the mathematical model into optimal angle parameters that can be directly used in engineering design. To achieve the optimal balance between safety and economy.

[0029] In a preferred embodiment of the present invention, step S2 specifically includes the following steps: S21, Based on the fluid dynamics theory of branched flow in a pipe, establish the resistance coefficient and the included angle for the inflow into the cross passage. The corrected function relationship between them; it should be noted that the local resistance of fluid flowing into the branch pipe is mainly determined by the flow separation and vortex loss at the bend, and the inclination angle. Directly altering the turning angle of the upstream and downstream fluids leads to different variation patterns in the drag coefficient. Therefore, both flue gas and air can be considered incompressible fluids, and steady-state flow (reaching a stable state after the exhaust system starts) can be taken into account. The pressure loss at the inlet of the exhaust cross passage 20 is primarily due to local drag loss, with friction loss as a secondary factor. Thus, the drag coefficient here is mainly a local pressure coefficient, and therefore, it can be defined as... The resistance coefficient is the amount of smoke flowing from the upstream tunnel 110 into the exhaust cross tunnel 20 (upstream is smoke). The resistance coefficient for the flow from downstream tunnel 120 into the exhaust cross passage 20 (downstream is fresh air) is then calculated based on fluid dynamics experiments and theories of branched flow in pipes (see Idelchik IE's *Handbook of Hydraulic Resistance*), for an inclination angle of... The branch whose drag coefficient can be expressed as the reference drag coefficient ( The product of (when =90°) and an angle correction function: in, The resistance coefficient of the smoke exhaust cross passage 20 when it is set perpendicularly to the tunnel body 10, allowing the upstream tunnel 110 to flow into the smoke exhaust cross passage 20, has a typical empirical value range of 0.5 to 1.0. When the smoke exhaust cross passage 20 is set vertically between the tunnel body 10 and the smoke exhaust cross passage 20, the resistance coefficient of the downstream tunnel 120 flowing into the smoke exhaust cross passage 20 has a typical empirical value range of 0.8~1.2, which can be determined by experiments or experience and is a constant. for Angle correction function, for Angle correction functions, both are fitted Follow The mathematical expression of change.

[0030] Furthermore, by analyzing the kinetic energy loss and pressure gradient of the fluid at the bend, the approximate form of the correction function can be derived as follows: Among them, for upstream inflow :when When the angle decreases from 90°, the flue gas turning angle (90°- As the energy loss coefficient decreases, the flow path becomes smoother, the separation vortex weakens, and thus the energy loss coefficient decreases linearly. This is the empirical coefficient for the angle correction of the upstream tunnel 110, typically between 0.6 and 0.8, reflecting the efficiency of flow improvement. For downstream inflow... When fresh air enters the inclined transverse tunnel downstream, it actually needs to go through a (180°- The larger turning angle of the reverse pressure gradient, and the opposite direction of the flow direction to the main airflow, increase the drag coefficient in the form of a quadratic function. This is an empirical correction coefficient for the 120° angle of the downstream tunnel, typically between 0.3 and 0.5. and All of these can be obtained through theoretical analysis or CFD data fitting.

[0031] S22, based on Bernoulli's equation and the law of conservation of mass, establish the mapping relationship between the resistance coefficient flowing into the cross tunnel and the flow velocity flowing into the flue gas cross tunnel 20; it is worth noting that, applying Bernoulli's equation and the law of conservation of mass at the confluence point, for the upstream branch and the downstream branch, respectively: in, and These represent the small frictional losses from upstream tunnel 110 and downstream tunnel 120 to the confluence point, respectively. For simplicity, these losses can be ignored in the preliminary optimization model, and the remaining values ​​can be directly obtained from the basic database. Furthermore, since the pressures near the confluence point in upstream tunnel 110 and downstream tunnel 120 are approximately equal after the exhaust fan starts (…), ≈ After simplification, the flow rate ratio can be obtained: This means that the ratio of upstream to downstream inflow velocity is inversely proportional to the square root of the ratio of resistance coefficients. In other words, increasing downstream resistance and decreasing upstream resistance can significantly increase the inflow velocity of upstream flue gas, thereby preferentially drawing in flue gas.

[0032] S23, Establish the flue gas capture rate model based on the correction function relationship and the mapping relationship. It should be noted that, based on the continuity of flow, the total flow into the transverse tunnel... ,in, The effective inflow area of ​​upstream tunnel 110, The effective inflow area of ​​the downstream tunnel 120 is typically assumed to be... Therefore, the volumetric flow rate of flue gas flowing in from upstream can be obtained. Accounting for a portion of total inflow The proportion, i.e., the flue gas capture rate η(α), can be expressed as: Substituting the velocity ratio formula, we obtain the core expression for the flue gas capture rate model: Substituting the drag coefficient model into the equation, the flue gas capture rate model can be obtained. Defined as: As can be seen from the defined model, with Decrease Decrease Increasing the value of the fraction within the square root reduces the value of the fraction within the square root, ultimately leading to... Increasing means decreasing. It can effectively improve the flue gas capture rate; however, it is understandable that simply maximizing it... This will lead to It approaches 0, but at this point the length of the transverse tunnel is... As the value approaches infinity, the engineering cost becomes unacceptable. Therefore, a comprehensive benefit function balancing performance and cost needs to be constructed to achieve this balance.

[0033] In a preferred embodiment of the present invention, step S3 specifically includes the following steps: S31, Determine the included angle based on spatial geometric projection relationships. The actual length of the horizontal tunnel below ; in, ; S32, based on the actual transverse tunnel length Determine the actual excavation volume ; in, ; S33, based on the actual transverse tunnel length and the actual excavation volume Establish an engineering cost model This makes the engineering cost dimensionless, with vertical design as the benchmark, which facilitates subsequent weighted coupling with the normalized flue gas capture rate. in, This indicates the excavation volume when the smoke exhaust cross passage 20 is vertically positioned between the tunnel body 10 and the tunnel; thus, it can be seen that, with... Decrease, sin Decrease It increases dramatically in an inverse proportion. When When the angle is reduced from 90° to 60°, the cost increases by approximately 15% (1 / sin60∘≈1.15); but when When the angle is reduced to 40°, the cost increases by more than 55% (1 / sin40∘≈1.56), therefore, in a preferred embodiment, The value range is usually between 50° and 75°.

[0034] Furthermore, in step S4, the flue gas capture rate model... pass After normalization, the normalized flue gas capture rate is obtained. , to represent the performance improvement factor relative to the vertical design; where, The smoke capture rate is the smoke exhaust cross passage 20 being set vertically between the tunnel body 10 and the smoke exhaust cross passage 20.

[0035] Furthermore, the comprehensive benefit objective function Defined as: Understandably, by normalizing and weighting the two contradictory objectives of smoke extraction efficiency and engineering cost, a unified comprehensive benefit evaluation index can be constructed to achieve a quantitative balance between safety and economy, thus solving the problem of the inability to scientifically balance safety and cost in traditional design.

[0036] in, This is a weighting coefficient for the flue gas capture rate. For cost control, the weighting coefficient is... + =1, > Weighting coefficient and The value is determined based on the mandatory principles of tunnel disaster prevention and safety design. According to the "safety first" design principle in relevant standards such as the "Specifications for Ventilation Design of Highway Tunnels" (JTG / TD70 / 2-02), the weight of smoke extraction efficiency (safety) must be higher than the weight of engineering cost (economy), that is, it must meet the following requirements. > In practical applications, designers can achieve a value of 0.6 ≤ ≤0.9, 0.1≤ Within the range of ≤0.4 and w1+w2=1, and based on the common practice in the engineering industry of balancing safety and economy, it is recommended to take... =0.7, =0.3 is used as a typical design value. This value ensures that safety factors play a dominant role in optimization decisions. Those skilled in the art can make adaptive adjustments within the above range according to the specific safety level and cost control requirements of the project.

[0037] Furthermore, step S5 specifically includes the following steps: S51, determine the weighting coefficient of the flue gas capture rate. The weighting coefficient of the aforementioned cost control The included angle The value of is determined first; the values ​​of the independent variables to be used in the model calculation for the current round are then used for the calculation.

[0038] S52, the weighting coefficient of the determined flue gas capture rate. The weighting coefficient of the aforementioned cost control The included angle Substituting the value of into the comprehensive benefit objective function In order to obtain and record Discrete values; weighting coefficients for determining the flue gas capture rate. The weighting coefficient of the aforementioned cost control The included angle After determining the value, iterative calculations are performed to determine the included angle. Substitute into as well as In the calculation, the weighting coefficients are then substituted into the comprehensive benefit objective function. If the angle is in the middle, the angle of the current iteration can be output. corresponding Discrete values.

[0039] S53, Adjust the included angle The value of is determined, and steps S51-S52 are repeated iteratively until the solution is obtained. The value is iterated through all values ​​within its preset range; where, =50°, 51°...74°, 75°; due to the weighting coefficient of the flue gas capture rate in the same round of iterations. The weighting coefficient of the aforementioned cost control The specific safety level and cost control requirements of the project are usually determined as the fixed value for the iteration cycle, so only the included angle needs to be adjusted. The values ​​are then substituted back into the various models and mapping relationships to repeat steps S51-S52, iteratively solving until all preset values ​​are obtained. All values ​​have been calculated; the angle difference for a single adjustment is in units of 1°, and the traversal iteration range is usually 0°~90°, while 50°~75° is a preferred preset range in a preferred embodiment of this application, which can greatly reduce the number of iterations and improve efficiency. Those skilled in the art can adjust the angle difference for a single adjustment and the preset range according to actual needs.

[0040] S54, based on various Discrete value plotting Curve, and observe In the curve The included angle corresponding to the maximum value The optimal design angle for the smoke exhaust cross passage 20. ; All of Discrete dataset output becomes The angle corresponding to the peak of the curve is the optimal design angle. It is worth mentioning that, in order to obtain curves under various parameters, the values ​​of the weighting coefficients can be adjusted appropriately, and then the values ​​can be iterated again. Another round of optimization design will be carried out.

[0041] This application also provides a highway tunnel smoke exhaust system, applied to the method for optimizing the smoke exhaust angle of a highway tunnel as described above, comprising a tunnel body 10 and a smoke exhaust cross passage 20, wherein the smoke exhaust cross passage 20 is inclined and one end is connected to the tunnel body 10; wherein... The tunnel body 10 includes an upstream tunnel 110 and a downstream tunnel 120 that are internally connected, and the smoke exhaust cross passage 20 and the downstream tunnel 120 form an angle. And the included angle The angle is acute. When a fire occurs, the smoke exhaust fan starts and generates a suction negative pressure. Because the smoke exhaust cross passage 20 is designed with an acute angle and tilts downstream, the resistance of the upstream smoke flowing into the cross passage is small and the flow rate is fast, while the resistance of the downstream fresh air flowing into the cross passage is large and the flow rate is slow. This forces the effective pressure difference generated by the fan to act on the upstream smoke side first, thus suppressing the "air short circuit" effect from the root.

[0042] To facilitate understanding by those skilled in the art, a preferred embodiment is provided below: In an embodiment of a two-way separated highway tunnel, the width of a single tunnel is W=10m, and the design longitudinal wind speed is... =2.5m / s. A 20mm smoke exhaust cross passage is planned in the middle of the tunnel. The original vertical design (α=90°) had a cross passage length of... =30m. Using the above model, calculations were performed to obtain different values ​​of α. and ,Pick =0.7, =0.3, calculate J(α), and output. curve.

[0043] exist The curve shows that J(α) is at its maximum when α = 60°. At this point, compared to It is expected to increase by about 20%, while the relative cost =1 / sin60°≈1.15, meaning the workload only increases by about 15%. Therefore, the smoke exhaust cross passage 20 is designed with an angle α=60° with the axis of the downstream tunnel 120. In the event of a fire, upstream smoke can flow more smoothly into the smoke exhaust cross passage 20, while the amount of fresh air mixed in downstream is effectively suppressed, significantly improving smoke exhaust efficiency.

[0044] It is worth noting that, please refer to the appendix. Figure 3 The diagram compares the smoke extraction performance of a traditional smoke extraction cross passage system with that of the smoke extraction cross passage system described in this application, where the angle between the cross passage and the tunnel is an acute angle of 60° (300 seconds after the fire starts, i.e., the golden five minutes for fire escape). It shows that in the case of the traditional smoke extraction cross passage system, a large amount of smoke fails to be effectively discharged from the cross passage within 300 seconds of the fire starting, spreading to the downstream tunnel and endangering downstream evacuation safety. However, in the case of the smoke extraction system of this invention, most of the smoke enters the smoke extraction cross passage and is discharged from the tunnel within 300 seconds of the fire starting, with only a small portion entering the downstream tunnel. Furthermore, the distance the smoke spreads downstream is much shorter than in the traditional case, demonstrating a better smoke extraction effect.

[0045] Further, please refer to the appendix. Figure 4 This is a horizontal flow field diagram at a height of 3m above the road surface for a traditional cross-tunnel smoke exhaust system (right-angle connection, no diversion structure) in one embodiment. It can be seen that in the traditional right-angle connection structure, when the smoke flows from the upstream of the tunnel through the cross-tunnel entrance, a significant large-scale separation vortex is formed on the inner side of the right-angle turn. This vortex is strong and wide, with the vortex zone's lateral width accounting for approximately 30% of the cross-tunnel entrance width and extending longitudinally to 15m inside the cross-tunnel. The fluid within the vortex zone exhibits periodic swirling motion, with some smoke stagnating or even flowing out in the opposite direction. Simultaneously, it prevents the mainstream smoke from flowing closely along the inner wall of the turn, forming a distinct "cavity area." In the diagram, X represents the lateral length of the tunnel, and Y represents the longitudinal length of the tunnel.

[0046] Please see the appendix Figure 5 This is a flue gas flow field diagram at a height of 3m above the road surface of the smoke exhaust system after optimizing the angle in a preferred embodiment. After adopting the optimized acute-angle connection, the flow field morphology is fundamentally improved. Flow separation is effectively controlled; the vortex zone's lateral width accounts for only 20% of the width of the cross-tunnel entrance, and its longitudinal extension only reaches 10m inside the cross-tunnel. After entering the cross-tunnel, the flue gas quickly forms a stable pipe flow velocity distribution, with all streamlines exhibiting a regular, centripetal convergence shape, free from turbulence and intersection. Simultaneously, observing the streamlines entering the cross-tunnel from the upstream and downstream tunnels reveals that the main air entering the smoke exhaust cross-tunnel is upstream flue gas rather than downstream fresh air. This indicates that the acute-angle structure increases the downstream air inflow resistance, consistent with the model prediction described in this application. In the figure, X represents the lateral length along the tunnel, and Y represents the longitudinal length along the tunnel.

[0047] Finally, a CFD fire simulation can be performed on the aforementioned tunnel to verify the reliability of the invention. The smoke capture rate at different α angles is shown in the table below.

[0048] The results show that as α decreases, the flue gas capture rate increases rapidly, while the downstream air mixing rate decreases rapidly. When the angle exceeds 60°, the effect of changing the angle α on improving the flue gas capture rate becomes increasingly limited, and the civil engineering costs continue to increase.

[0049] Furthermore, based on calculations, recommended angle α is also provided for tunnels with different characteristics: Those skilled in the art can narrow down the range of angle iterations based on different working conditions, thereby improving the efficiency of optimization iterations.

[0050] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for optimizing the smoke exhaust angle in a highway tunnel, characterized in that, Includes the following steps: S1, Obtain basic data on the vertical setting of the smoke exhaust cross passage and the tunnel body in the highway tunnel smoke exhaust system, in order to build a basic database; S2, Establish a flue gas capture rate model based on the aforementioned basic database. This is to indicate the angle between the central axis of the smoke exhaust cross passage and the central axis of the tunnel body. The influence of the proportion of fire smoke drawn into the cross passage within the tunnel; where the included angle It is an acute angle; S3, Establish an engineering cost model based on the aforementioned basic database. , to represent the included angle The impact of the construction cost of the smoke exhaust tunnel; S4, the flue gas capture rate model Perform normalization processing and compare it with the engineering cost model. Weighted coupling to construct a comprehensive benefit objective function ; S5, regarding the comprehensive benefit objective function Perform iterative optimization to obtain the angle that maximizes the overall benefit objective function. The optimal design angle for the horizontal smoke exhaust duct. .

2. The method for optimizing the smoke exhaust angle of a highway tunnel according to claim 1, characterized in that, The junction of the upstream tunnel of the tunnel body, the downstream tunnel of the tunnel body, and the smoke exhaust cross passage forms a confluence point; The basic database includes the static pressure of the upstream tunnel at the confluence point. The static pressure of the downstream tunnel at the confluence point Static pressure at the entrance of the smoke exhaust duct The flow rate of flue gas flowing from upstream into the flue gas duct The airflow velocity from downstream into the smoke exhaust duct Density of flue gas / air mixture The length of the smoke exhaust cross passage when it is set perpendicularly to the tunnel body Cross-sectional area .

3. The method for optimizing the smoke exhaust angle of a highway tunnel according to claim 2, characterized in that, Step S2 specifically includes the following steps: S21, Based on the fluid dynamics theory of branched flow in a pipe, establish the resistance coefficient and the included angle for the inflow into the cross passage. The relationship between the correction functions; S22. Based on Bernoulli's equation and the law of conservation of mass, establish the mapping relationship between the drag coefficient flowing into the cross tunnel and the flow velocity flowing into the flue gas cross tunnel. S23, Establish the flue gas capture rate model based on the correction function relationship and the mapping relationship. .

4. The method for optimizing the smoke exhaust angle of a highway tunnel according to claim 1, characterized in that, The flue gas capture rate model Defined as: in, The resistance coefficient of the smoke exhaust cross passage flowing into the smoke exhaust cross passage from the upstream tunnel when it is set perpendicularly to the tunnel body. When the smoke exhaust cross passage is set perpendicularly to the tunnel body, the resistance coefficient of the downstream tunnel flowing into the smoke exhaust cross passage is determined. An empirical coefficient is used to correct the angle of the upstream tunnel. An empirical coefficient is used to correct the angle of the downstream tunnel.

5. The method for optimizing the smoke exhaust angle of a highway tunnel according to claim 2, characterized in that, Step S3 specifically includes the following steps: S31, Determine the included angle based on spatial geometric projection relationships. The actual length of the horizontal tunnel below ; in, ; S32, based on the actual transverse tunnel length Determine the actual excavation volume ; in, ; S33, based on the actual transverse tunnel length and the actual excavation volume Establish an engineering cost model ; in, This indicates the excavation volume when the smoke exhaust cross passage is set vertically between the tunnel body and the tunnel body.

6. The method for optimizing the smoke exhaust angle of a highway tunnel according to claim 1, characterized in that, In step S4, the flue gas capture rate model is... pass After normalization, the normalized flue gas capture rate is obtained. , to represent the performance improvement factor relative to the vertical design; where, The smoke capture rate is the result of a vertically positioned smoke exhaust cross passage between the cross passage and the tunnel body.

7. The method for optimizing the smoke exhaust angle of a highway tunnel according to claim 6, characterized in that, The comprehensive benefit objective function Defined as: in, This is a weighting coefficient for the flue gas capture rate. For cost control, the weighting coefficient is... + =1, > .

8. The method for optimizing the smoke exhaust angle of a highway tunnel according to claim 7, characterized in that, Step S5 specifically includes the following steps: S51, determine the weighting coefficient of the flue gas capture rate. The weighting coefficient of the aforementioned cost control The included angle The possible values ​​of ; S52, the weighting coefficient of the determined flue gas capture rate. The weighting coefficient of the aforementioned cost control The included angle Substituting the value of into the comprehensive benefit objective function In order to obtain and record Discrete values; S53, Adjust the included angle The value of is determined, and steps S51-S52 are repeated iteratively until the solution is obtained. The value is iterated through all values ​​within its preset range; where, =50°, 51°...74°, 75°; S54, based on various Discrete value plotting Curve, and observe In the curve The included angle corresponding to the maximum value The optimal design angle for the horizontal smoke exhaust duct. .

9. The method for optimizing the smoke exhaust angle of a highway tunnel according to claim 7, characterized in that, The weighting coefficient of the flue gas capture rate The value range is 0.6≤ ≤0.9, the weighting coefficient of the cost control The value range is 0.1≤ ≤0.

4.

10. A smoke extraction system for highway tunnels, applied to the method for optimizing the smoke extraction angle of highway tunnels as described in any one of claims 1-9, characterized in that, It includes a tunnel body and a smoke exhaust cross passage, wherein the smoke exhaust cross passage is inclined and one end is connected to the tunnel body; wherein, The tunnel body includes an internally connected upstream tunnel and a downstream tunnel, and the smoke exhaust cross passage forms an angle with the downstream tunnel. And the included angle It is an acute angle.

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