A method for smoke exhaust design of adjacent tunnels for a canopy with restricted boundary

Abstract

The application relates to the technical field of tunnel engineering, and provides a smoke exhaust design method for an adjacent tunnel of a limited boundary of a light-shielding shed, which comprises the following steps: obtaining a critical smoke exhaust amount of a smoke exhaust system of a target tunnel section, determining an optimal smoke blocking height of a fan-shaped smoke baffle according to the critical smoke exhaust amount, obtaining a rated smoke exhaust amount of each smoke exhaust component, determining the number of the smoke exhaust components according to the critical smoke exhaust amount and the rated smoke exhaust amount, and configuring the smoke exhaust system according to the number of the smoke exhaust components and the optimal smoke blocking height of the fan-shaped smoke baffle. After the smoke exhaust system is started, the number of fans that need to be added in a downstream tunnel can be determined according to an actual flow ratio. The application can improve the safety of the downstream tunnel, improve the evacuation environment of the downstream tunnel, reduce the number of fans needed in the downstream tunnel, and save engineering cost. According to the obtained number of fans, the evacuation environment of the downstream tunnel can be effectively improved, the number of fans is prevented from being set too much, and the engineering cost is effectively optimized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel engineering, and particularly relates to a smoke exhaust design method for adjacent tunnels with limited boundary of light-shading shed. BACKGROUND

[0002] The fire safety problem of highway tunnel is a key problem affecting the resilience of transportation. When a fire occurs in a highway tunnel, the fire smoke moves forward along the tunnel under the action of the smoke exhaust fan and gradually subsides, which may hinder the escape of personnel in the tunnel. In order to reduce this risk, researchers have explored various smoke control methods, including air curtains, vertical shaft smoke exhaust systems, water curtains, etc.

[0003] With the gradual expansion of highway tunnels to mountainous areas, the highway adjacent to tunnel groups is increasing in mountainous areas. For example, on the Lhasa-Shigatse route in China, the longitudinal distance between the Quda Tunnel and the Badongshan Tunnel is only 29 meters; the distance between the tunnels in the Zijinshan Tunnel group in Hunan Province, China is 118m. Generally, adjacent tunnels with a distance of less than 200m are called adjacent tunnels. A large number of studies have shown that there is a significant cross-flow of pollutants between adjacent tunnels. It is worth noting that due to the short connection section between adjacent tunnels, drivers will experience a sharp change in light environment when passing through these sections, leading to a rapid transition of visual light-dark adaptation process, which can easily cause visual impairment, interfere with the perception of driving information, and affect driving safety. In view of this, a light-shading shed is often provided in the connection section between adjacent tunnels to improve the light environment at the entrance and exit of the tunnel.

[0004] The existence of the light-shading shed hinders the diffusion of pollutants and fire smoke exhausted from the upstream tunnel, causing the pollutants and smoke to enter the downstream tunnel, affecting the ventilation and smoke exhaust of the downstream tunnel. At present, the influence is mainly reduced by increasing the number of fans in the downstream tunnel, which not only increases the engineering cost, but also has poor evacuation environment and safety in the downstream tunnel.

[0005] In addition, since the cross-flow law and cross-flow ratio of pollutants between the upstream tunnel and the downstream tunnel are not clear, the number of fans that should be increased cannot be accurately determined, resulting in either insufficient number of fans leading to poor evacuation environment in the downstream tunnel or excessive number of fans leading to increased engineering cost.

[0006] In view of this, it is necessary to provide a smoke exhaust design method for adjacent tunnels with limited boundary of light-shading shed to solve or at least alleviate the above-mentioned defects. SUMMARY

[0007] The main purpose of the present application is to provide a smoke exhaust design method for adjacent tunnels with limited boundary of light-shading shed, so as to solve the technical problem that the influence of fire smoke is reduced by increasing the number of fans in the downstream tunnel in the prior art, which not only increases the engineering cost, but also has poor evacuation environment in the downstream tunnel.

[0008] To achieve the above object, the application provides a smoke exhaust design method for a sheltered tunnel adjacent to a restricted boundary, comprising the following steps:

[0009] S1, obtaining a critical smoke exhaust amount of a smoke exhaust system of a target tunnel section; wherein the target tunnel section comprises an upstream tunnel section, a sheltered tunnel section and a downstream tunnel section connected in sequence, the smoke exhaust system comprises a smoke exhaust component for exhausting part of pollutants from the inside of the sheltered tunnel section to the outside of the sheltered tunnel section and a fan-shaped smoke baffle matched with the shape of the sheltered tunnel section, the smoke exhaust component and the fan-shaped smoke baffle are arranged one by one, and the fan-shaped smoke baffle is arranged downstream of the corresponding smoke exhaust component;

[0010] S2, determining an optimal smoke blocking height of the fan-shaped smoke baffle according to the critical smoke exhaust amount;

[0011] S3, obtaining a rated smoke exhaust amount of each smoke exhaust component, and determining the number of smoke exhaust components according to the critical smoke exhaust amount and the rated smoke exhaust amount, and configuring the smoke exhaust system according to the number of smoke exhaust components and the optimal smoke blocking height of the fan-shaped smoke baffle.

[0012] Preferably, the step S1 specifically comprises the following steps:

[0013] S11, establishing a tunnel three-dimensional model for the target tunnel section;

[0014] S12, obtaining a channeling ratio of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system; wherein the channeling ratio is the ratio of the average concentration of the target pollutant at the downstream tunnel entrance section to the average concentration of the target pollutant at the upstream tunnel exit section, and is used to quantify the degree of channeling of the target pollutant from the upstream tunnel to the downstream tunnel;

[0015] S13, sequentially performing curve fitting on the channeling ratios corresponding to different smoke exhaust amounts to obtain a channeling ratio-smoke exhaust amount curve;

[0016] S14, obtaining a node smoke exhaust amount corresponding to an inflection point of the channeling ratio-smoke exhaust amount curve, and taking the node smoke exhaust amount as the critical smoke exhaust amount.

[0017] Preferably, the step S2 specifically comprises the following steps:

[0018] S21, determining a dimensionless critical smoke exhaust amount Q2* by using the formula Q2*=Q2 / (V0×S); wherein Q2 is the critical smoke exhaust amount, V0 is a tunnel fire critical wind speed, and S is a tunnel section area;

[0019] S22, determining a dimensionless optimal smoke blocking height H max * by using the formula

[0020] ​S23, determining the optimal smoke blocking height H of the fan-shaped smoke blocking plate by using formula H max = H max max ; wherein, H1 is the net height of the tunnel.

[0021] Preferably, the step S3 further comprises the following steps:

[0022] S31, fixing the optimal smoke blocking height H after starting the smoke exhaust system max , obtaining the channeling ratio R0 of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system;

[0023] S32, fixing the critical smoke exhaust amount Q2, and obtaining the channeling ratio R1 of the tunnel three-dimensional model under different smoke blocking heights H;

[0024] S33, establishing a mathematical model of R1 / R0 and H / H max ;

[0025] S34, determining the actual channeling ratio R* of the tunnel three-dimensional model under actual different smoke exhaust amounts and actual different smoke blocking heights according to the channeling ratio R0 and the mathematical model;

[0026] S35, determining the number of fans to be added in the downstream tunnel according to the actual channeling ratio R*.

[0027] Preferably, the step S31 of obtaining the channeling ratio R0 of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system specifically comprises the following steps:

[0028] determining the actual smoke exhaust amount Q3 of the smoke exhaust system by using formula ; wherein, V n is the smoke exhaust duct speed of the nth smoke exhaust component, and S y is the cross-sectional area of the smoke exhaust duct; wherein, each smoke exhaust component comprises a smoke exhaust fan and a smoke exhaust duct, the smoke exhaust duct penetrates the sunshade and communicates with the internal space of the sunshade, and the smoke exhaust fan is arranged in the smoke exhaust duct to exhaust the smoke in the sunshade to the outside of the sunshade through the smoke exhaust duct;

[0029] determining the dimensionless critical smoke exhaust amount Q3* by using formula Q3* = Q2 / Q3;

[0030] determining the channeling ratio R0 of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system by using formula .

[0031] Preferably, the mathematical model of the step S33 is specifically as follows:

[0032]

[0033] ​Preferably, the step S34 specifically comprises the steps of:

[0034] The formula is The actual tunnel three-dimensional model is determined under the actual different smoke exhaust amount and the actual different smoke blocking height.

[0035] Preferably, the step S35 specifically comprises the steps of:

[0036] The formula is The number of fans to be added in the downstream tunnel is determined; wherein Q req(co) is the required air volume of the tunnel for diluting the channeling pollution; Q co is the pollution emission amount of the upstream tunnel, p0 is the standard atmospheric pressure, p is the atmospheric pressure of the tunnel site, T0 is the standard air temperature, T is the summer air temperature of the tunnel site, Qa is the air volume of a single fan, δ is the total pressure efficiency of the fan, and N is the number of fans to be added in the downstream tunnel.

[0037] Preferably, each smoke exhaust assembly further comprises a movable smoke blocking assembly connected with the fan-shaped smoke blocking plate, and the movable smoke blocking assembly comprises a roller shutter door, and an unfolding area of the roller shutter door is adjustably arranged.

[0038] Preferably, the step S35 further comprises the steps of:

[0039] S41, when there is no trapped person in the upstream of the sunshade section, the roller shutter door of any one smoke exhaust assembly is controlled to be below the road surface, and the smoke gas is completely blocked from spreading to the downstream tunnel;

[0040] S42, when the personnel in the downstream tunnel have completed evacuation, the roller shutter door is retracted, and all the fans of the upstream tunnel and the downstream tunnel are started until the environment in the upstream tunnel and the downstream tunnel reaches a normal state;

[0041] S43, all the smoke exhaust assemblies are closed.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] The present application provides a smoke exhaust design method for a tunnel adjacent to a sunshade restricted boundary, by obtaining the critical smoke exhaust amount of the smoke exhaust system of the target tunnel section, determining the optimal smoke blocking height of the fan-shaped smoke blocking plate according to the critical smoke exhaust amount, obtaining the rated smoke exhaust amount of each smoke exhaust assembly, and determining the number of smoke exhaust assemblies according to the critical smoke exhaust amount and the rated smoke exhaust amount, and configuring the smoke exhaust system according to the number of smoke exhaust assemblies and the optimal smoke blocking height of the fan-shaped smoke blocking plate.

[0044] This application reduces the velocity and ratio of smoke cross-flow during fires between tunnels, improves the evacuation environment of downstream tunnels, and enhances the safety and resilience of tunnels. It also reduces the amount of pollutants entering downstream tunnels (including in fire scenarios and normal traffic scenarios), reduces the number of fans required for downstream tunnels, and saves engineering costs. The number of fans determined by the formula can be dynamically adjusted according to actual needs. The resulting number of fans can effectively improve the evacuation environment of downstream tunnels while preventing the problem of excessive fan installation leading to high engineering costs. Attached Figure Description

[0045] 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.

[0046] Figure 1 This is a flowchart illustrating the design method in one embodiment of the present invention;

[0047] Figure 2 This is a flowchart illustrating the specific steps included in step S1 of one embodiment of the present invention.

[0048] Figure 3 This is a schematic cross-sectional view of a standard extra-long tunnel according to one embodiment of the present invention;

[0049] Figure 4 This is a schematic diagram of the crossflow ratio-exhaust volume curve in one embodiment of the present invention;

[0050] Figure 5 This is a schematic diagram showing a vortex formed at the top of the downstream tunnel side in one embodiment of the present invention;

[0051] Figure 6 The optimal smoke-blocking height H of the fan-shaped smoke baffle in one embodiment of the present invention max Corresponding curve diagram;

[0052] Figure 7 This is a schematic diagram corresponding to Formula 2 in one embodiment of the present invention;

[0053] Figure 8 This is a schematic diagram corresponding to Formula Six in one embodiment of the present invention;

[0054] Figure 9 This is a schematic diagram corresponding to Formula 7 in one embodiment of the present invention;

[0055] Figure 10 This is an elevation view of an application scenario of the smoke exhaust component in one embodiment of the present invention;

[0056] Figure 11 A top view of the smoke exhaust assembly in an embodiment of the present application;

[0057] Figure 12 A side view of the application scenario of the smoke exhaust assembly in an embodiment of the present application.

[0058] The purposes, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings.

[0059] Explanation of reference signs:

[0060] 10, smoke exhaust unit; 110, smoke exhaust fan; 120, smoke exhaust duct; 121, first vertical section; 122, second vertical section; 123, horizontal section; 124, drain hole; 210, vertical support rod; 220, support diagonal rod; 230, support column; 240, fixed connecting rod; 250, intermediate connecting rod; 260, column stabilizing rod; 310, fixed smoke blocking assembly; 311, fan-shaped smoke blocking plate; 320, movable smoke blocking assembly; 321, roller shutter door; 40, sunshade; 50, upstream tunnel; 60, downstream tunnel. DETAILED DESCRIPTION

[0061] It should be understood that the specific embodiments described herein merely exemplify the present application and are not intended to limit the present application.

[0062] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0063] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications will also change accordingly.

[0064] In addition, the descriptions related to "right part", "middle part" and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "right part", "middle part" can be explicitly or implicitly included at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0065] Please refer to the accompanying Figures 1 to 12 In an embodiment of the present application, a smoke exhaust design method for a restricted boundary adjacent tunnel of a sunshade is provided, comprising the following steps:

[0066] S1, obtaining the critical smoke exhaust amount of the smoke exhaust system of the target tunnel section; wherein the target tunnel section comprises an upstream tunnel section, a sunshade section and a downstream tunnel section connected in turn, the smoke exhaust system comprises a smoke exhaust component for exhausting part of the pollutants from the inside of the sunshade section to the outside of the sunshade section, and a fan-shaped smoke baffle 311 matched with the shape of the sunshade section, the smoke exhaust component and the fan-shaped smoke baffle 311 are arranged one by one, and the fan-shaped smoke baffle 311 is arranged downstream of the corresponding smoke exhaust component;

[0067] As a preferred embodiment, the step S1 specifically comprises the following steps:

[0068] S11, establishing a tunnel three-dimensional model for the target tunnel section; preferably, based on characteristic parameters such as tunnel length, cross-sectional size, sunshade 40 length, sunshade 40 height, fire heat release rate, a tunnel three-dimensional model with a size of 1:1 is established;

[0069] S12, obtaining the cross-flow ratio of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system; wherein the cross-flow ratio is the ratio of the average concentration of the target pollutant at the inlet cross section of the downstream tunnel 60 to the average concentration of the target pollutant at the outlet cross section of the upstream tunnel 50, which is used to quantify the degree of cross-flow of the target pollutant from the upstream tunnel 50 to the downstream tunnel 60;

[0070] S13, sequentially curve fitting the cross-flow ratios corresponding to different smoke exhaust amounts to obtain a cross-flow ratio-smoke exhaust amount curve;

[0071] S14, obtaining the node smoke exhaust amount corresponding to the inflection point of the cross-flow ratio-smoke exhaust amount curve according to the cross-flow ratio-smoke exhaust amount curve, and taking the node smoke exhaust amount as the critical smoke exhaust amount.

[0072] The specific implementation is as follows:

[0073] A standard long tunnel is selected as the research object (the cross-sectional size is, for example,Figure 3 As shown, the tunnel length is 3000 m, the heat release rate is 30 MW, and the wind speed in the tunnel is 3 m / s. The smoke channeling research under different smoke blocking heights and exhaust capacities is carried out, and it is found that the CO channeling ratio under different smoke blocking heights decreases (decreases) with the increase of the exhaust capacity of the smoke exhaust system, and reaches a stable stage after a certain value, as shown in Figure 4 As shown, the minimum exhaust capacity corresponding to the stable stage is the critical exhaust capacity Q2=80 m 3 / s. (Because after the fire occurs, the smoke gathers under the ceiling under the action of thermal buoyancy to form a certain thickness of smoke layer. The smoke exhaust system then sucks the smoke outward through the smoke exhaust port, and the suction increases with the increase of the exhaust capacity, and the thickness of the smoke layer sucked increases. However, when the exhaust capacity is large enough, the smoke layer is sucked through, and then the air below the smoke layer is sucked, that is, invalid exhaust. Therefore, there is a stable stage.)

[0074] As a preferred embodiment, each smoke exhaust assembly further comprises a movable smoke blocking assembly 320 connected with the fan-shaped smoke blocking plate 311, and the movable smoke blocking assembly 320 comprises a roller shutter door 321, the opening area of which is adjustably arranged.

[0075] Specifically, the fan-shaped smoke blocking plate 311 slows down the spread of smoke from the upstream tunnel 50 to the downstream tunnel 60, and at the same time, the fan-shaped smoke blocking plate 311 is arranged downstream of the smoke exhaust duct 120 to gather smoke and facilitate smoke exhaust. Preferably, the material of the fan-shaped smoke blocking plate 311 is a fire-resistant and heat-insulating plate with a thickness of 3-5 mm. The lower edge of the fan-shaped smoke blocking plate 311 is provided with a stainless steel horizontal rod for fixing to the sunshade 40. Preferably, the fan-shaped smoke blocking plate 311 is sealingly connected with the sunshade 40, the fan-shaped smoke blocking plate 311 is arranged downstream of the smoke exhaust duct 120, and the fan-shaped smoke blocking plate 311 is located between the top boundary of the tunnel building and the sunshade 40.

[0076] The roller shutter door 321 is arranged in the smoke blocking roller shutter box, and the maximum lower height can reach the road surface. The top of the smoke blocking roller shutter box is fixed to the stainless steel horizontal rod, and a roller shutter control system is provided. The existing mature device can be used, and the lifting of the fireproof roller shutter can be controlled.

[0077] S2, determining the optimal smoke blocking height of the fan-shaped smoke blocking plate 311 according to the critical exhaust capacity;

[0078] As a specific example, according to the numerical simulation results Figures 3-6 , the working condition: the size is as shown in Figure 3 The length unit on the graph is cm; H=3.5 m, Q2=100 m 3 / s, fire heat release rate 30 MW), it is found that the existence of the sunshade 40 aggravates the pollutant crossflow between the adjacent tunnels, but the device of the present application can effectively control the pollutant crossflow between the adjacent tunnels under the action of the sunshade 40, the fan-shaped smoke baffle 311 limits the spread of the flue gas, and the smoke exhaust system timely exhausts the flue gas, and the specific effects are: the temperature of the downstream tunnel 60 is reduced, the visibility of the downstream tunnel 60 is improved, the CO crossflow ratio between the tunnels is reduced, etc. At the same time, numerical simulation under different smoke exhaust amounts and smoke baffle heights is carried out, and the results show that: under the same smoke exhaust amount, with the increase of the smoke baffle height, the CO crossflow ratio between the adjacent tunnels first decreases and then increases, and there is an optimal smoke baffle height, as shown in Figure 6 .

[0079] There are mainly two reasons: (1) the fan-shaped smoke baffle 311 can only slow down and gather the flue gas, and cannot completely block the flue gas from spreading to the downstream. With the increase of the thickness of the gathered flue gas layer and the gradual settlement of the flue gas (in the diffusion process, the hot air is continuously entrained and heat exchanged between the cold and hot air, the temperature of the flue gas is reduced, and the flue gas appears to settle), the flue gas will spread to the downstream along the lower edge of the fan-shaped smoke baffle 311. With the increase of the height of the fan-shaped smoke baffle 311, the lower edge of the fan-shaped smoke baffle 311 is lower, and the downstream flue gas is lower, so that more flue gas crossflows to the downstream tunnel 60. (2) The fan-shaped smoke baffle 311 hinders the horizontal movement of the upper hot air flow, and forms a vortex at the top of the downstream side, as shown in Figure 5 . With the increase of the height H of the fan-shaped smoke baffle 311, the vortex at the top of the downstream side of the fan-shaped smoke baffle 311 increases, which easily disturbs the flue gas layer, accelerates the settlement of the flue gas, and under the push of the horizontal air flow, is more easily enters the downstream tunnel 60 rather than being discharged from the gap between the sunshade 40 and the tunnel top.

[0080] As a preferred embodiment, the step S2 specifically comprises the following steps:

[0081] S21, determining the dimensionless critical smoke exhaust amount Q2* by using Formula One: Q2*=Q2 / (V0×S); wherein, Q2 is the critical smoke exhaust amount, unit: m 3 / s, V0 is the critical wind speed of the tunnel fire, unit: m / s, and S is the tunnel section area, unit: m 2 ;

[0082] S22, determining the dimensionless optimal smoke baffle height H max * by using Formula Two: max max ;

[0083] S23, determining the optimal smoke baffle height H max of the fan-shaped smoke baffle 311 by using Formula Three: H max =H max *×H1; wherein, H1 is the net height of the tunnel, unit: m;

[0084] It is worth noting that in order to obtain the optimal smoke blocking height H max , more working condition test researches are carried out, and the dimensionless critical smoke exhaust amount Q2* and the dimensionless optimal smoke blocking height H max * are related, as shown in Figure 7 .

[0085] S3, obtaining the rated smoke exhaust amount of each smoke exhaust component, and determining the number of smoke exhaust components according to the critical smoke exhaust amount and the rated smoke exhaust amount, and configuring the smoke exhaust system according to the number of smoke exhaust components and the optimal smoke blocking height of the fan-shaped smoke blocking plate 311. For example, according to the sum of the smoke exhaust amounts of all smoke exhaust components, which is greater than the critical smoke exhaust amount, the number of smoke exhaust components n=3 can be calculated, so that three smoke exhaust components can be arranged in the light-shielding shed section along the longitudinal direction of the tunnel, and one fan-shaped smoke blocking plate 311 is arranged at the downstream position of each smoke exhaust component.

[0086] As a preferred embodiment, the step S3 further includes the step:

[0087] S31, after starting the smoke exhaust system, fixing the optimal smoke blocking height H max , obtaining the cross-flow ratio R0 of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system;

[0088] Further, the step S31 of obtaining the cross-flow ratio R0 of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system specifically includes the following steps:

[0089] The actual smoke exhaust amount Q3 of the smoke exhaust system is determined by using formula four: ; wherein, V n is the wind speed of the nth smoke exhaust component, and S y is the cross-sectional area of the smoke exhaust duct 120; wherein each smoke exhaust component includes a smoke exhaust fan 110 and a smoke exhaust duct 120, the smoke exhaust duct 120 penetrates the light-shielding shed 40 and communicates with the internal space of the light-shielding shed 40, and the smoke exhaust fan 110 is arranged in the smoke exhaust duct 120 to exhaust the smoke in the light-shielding shed 40 to the outside of the light-shielding shed 40 through the smoke exhaust duct 120;

[0090] The dimensionless critical smoke exhaust amount Q3* is determined by using formula five: Q3*=Q2 / Q3;

[0091] The cross-flow ratio R0 of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system is determined by using formula six: .

[0092] It should be noted that in the actual operation process, the smoke exhaust system may not be able to provide the required critical smoke exhaust volume Q2 due to factors such as damage to the smoke exhaust fan 110, insufficient voltage leading to reduced fan efficiency, and the like. Therefore, the cross-flow ratio R0 of the tunnel three-dimensional model under different smoke exhaust volumes needs to be obtained, so as to adjust the number of downstream tunnel 60 fans to be turned on.

[0093] As Figure 8 shown, the experimental research results show that the cross-flow ratio R0 and the dimensionless critical smoke exhaust volume Q3* are related.

[0094] S32, the fixed critical smoke exhaust volume Q2, the cross-flow ratio R1 of the tunnel three-dimensional model under different smoke blocking heights H is obtained;

[0095] It should also be noted that in the actual operation process, the fan-shaped smoke baffle 311 may not be able to provide the optimal smoke blocking height H max required by the design due to site conditions. Therefore, by fixing the critical smoke exhaust volume Q2, the cross-flow ratio R1 of the tunnel three-dimensional model under different smoke blocking heights H is obtained, so as to adjust the number of downstream tunnel 60 fans to be turned on. Both steps S31 and S32 adopt the technical idea of the control variable method.

[0096] S33, a mathematical model of R1 / R0 and H / H max is established;

[0097] Further, the mathematical model of step S33 is specifically:

[0098]

[0099] Specifically, the mathematical model of step S33, i.e., formula seven, is shown in the accompanying Figure 9 .

[0100] S34, according to the cross-flow ratio R0 and the mathematical model, the actual cross-flow ratio R* of the tunnel three-dimensional model under actual different smoke exhaust volumes and actual different smoke blocking heights is determined;

[0101] Preferably, the step S34 specifically includes the steps of:

[0102] The actual cross-flow ratio R* of the tunnel three-dimensional model under actual different smoke exhaust volumes and actual different smoke blocking heights is determined by formula .

[0103] Specifically, the simultaneous equations of formula six and formula seven can obtain the function of the actual cross-flow ratio R*, i.e., formula eight.

[0104] S35, according to the actual cross-flow ratio R*, the number of fans to be increased in the downstream tunnel 60 is determined.

[0105] Further, the step S35 specifically comprises steps of:

[0106] Using formula nine: determining the number of fans to be added to the downstream tunnel 60; wherein, Q req(co) is the required air volume for diluting and channeling pollutants in the tunnel, unit: m 3 / s, Q co is the pollutant emission of the upstream tunnel 50, unit: m 3 / s, which can be obtained from the tunnel ventilation design document, p0 is the standard atmospheric pressure, unit: kN / m 2 , taking 101.325 kN / m 2 , p is the atmospheric pressure at the tunnel site, unit: kN / m 2 , T0 is the standard air temperature, unit K, preferably taking 273 K, T is the summer air temperature at the tunnel site, unit: K, Q a is the air volume of a single fan, unit m 3 / s: δ is the total pressure efficiency of the fan, taking 80% as a specific example, N is the number of fans to be added to the downstream tunnel 60, unit: units.

[0107] Specifically, according to formula ten of the prior art: and formula eleven: Formula eight, formula ten, formula eleven can be obtained by formula nine.

[0108] From the above formula, it can be known that through the formula, the actual number of fans to be added under actual different smoke exhaust volumes and actual different smoke blocking heights N can be obtained, and the number of fans obtained can effectively improve the evacuation environment of the downstream tunnel 60, and can prevent the number of fans from being set too much, resulting in high engineering cost.

[0109] As a preferred embodiment, the step S35 further comprises steps of:

[0110] S41, when there is no trapped person upstream of the sunshade section, controlling the roller shutter door 321 below any one smoke exhaust assembly to the road surface to completely block the spread of smoke gas to the downstream tunnel 60; thereby improving the evacuation environment of the downstream tunnel 60 and prolonging the available evacuation time of the downstream tunnel 60.

[0111] S42, when the personnel in the downstream tunnel 60 have completed evacuation, retracting the roller shutter door 321 and opening all the fans of the upstream tunnel 50 and the downstream tunnel 60 until the environment in the upstream tunnel 50 and the downstream tunnel 60 reaches the normal state; the definition of the normal state is, for example, no fire smoke, no high temperature, and no toxic and harmful gas content reduced to below the safety value.

[0112] S43, closing all the smoke exhaust assemblies.

[0113] Please refer to the attached drawings Figures 10 to 12 As a preferred embodiment, each of the smoke exhaust assemblies comprises a smoke exhaust unit 10 and a support assembly (not shown in the figure), wherein the smoke exhaust unit 10 comprises a smoke exhaust fan 110 and a smoke exhaust duct 120, the smoke exhaust duct 120 penetrates the sunshade 40 and communicates with the internal space of the sunshade 40, the smoke exhaust fan 110 is arranged in the smoke exhaust duct 120 to exhaust the smoke in the sunshade 40 to the outside of the sunshade 40 through the smoke exhaust duct 120, and the support assembly is used to support the smoke exhaust fan 110.

[0114] In the scheme, when smoke or other pollutants appear in the sunshade 40, the smoke exhaust fan 110 is started to work, and the smoke exhaust fan 110 sucks part of the smoke in the sunshade 40 into the smoke exhaust duct 120, and then the smoke is exhausted to the outside of the sunshade 40 through the smoke exhaust duct 120, so as to achieve the purpose of smoke exhaust. By arranging multiple smoke exhaust devices in the sunshade 40, part of the smoke in the sunshade 40 can be quickly and effectively exhausted, so as to reduce the smoke or pollutants entering the downstream tunnel 60, improve the safety of the downstream tunnel 60, improve the evacuation environment of the downstream tunnel 60, and also reduce the number of fans required for the downstream tunnel 60, saving engineering cost.

[0115] As a preferred embodiment, the smoke exhaust duct 120 comprises a first vertical section 121, a second vertical section 122 and a horizontal section 123 connected in sequence along the extension direction of the smoke exhaust duct 120, the cross-sectional area of the first vertical section 121 increases in sequence from top to bottom, the first vertical section 121 penetrates the sunshade 40 and communicates with the internal space of the sunshade 40, the smoke exhaust fan 110 is arranged in the second vertical section 122, and the second vertical section 122 and the horizontal section 123 are L-shaped in space and are both located outside the sunshade 40.

[0116] Specifically, the cross-sectional area of the first vertical section 121 increases in sequence from top to bottom, which is similar to the principle of a Venturi tube, and can accelerate the flow of smoke to some extent. When the smoke enters the first vertical section 121 from the inside of the sunshade 40, the flow rate of the smoke will increase due to the gradual decrease of the cross-sectional area, thereby enhancing the smoke exhaust effect to some extent.

[0117] The upper part of the first vertical section 121 in the shape of a rhombic table is connected to the L-shaped smoke exhaust duct 120 (i.e. the second vertical section 122 and the horizontal section 123). The wall material of the second vertical section 122 and the horizontal section 123 is preferably 2-3 mm stainless steel material, and the cross-sectional size is 1*1 m. The length of the second vertical section 122 and the horizontal section 123 is both 2.5 m, and a 90° bending section is arranged between them.

[0118] As a preferred embodiment, the support assembly comprises a vertical support rod 210, a support inclined rod 220 and a support column 230, wherein the top of the vertical support rod 210 is fixedly connected with the smoke exhaust fan 110, the high end of the support inclined rod 220 is connected with the bottom of the vertical support rod 210, the top of the support column 230 is connected with the low end of the support inclined rod 220, the bottom of the support column 230 is connected with the ground, and the support column 230 is arranged between the side boundary of the tunnel construction and the light-shielding shed 40.

[0119] Specifically, the vertical support rod 210 is fixedly connected with the smoke exhaust fan 110, thereby ensuring the stable support of the fan in the vertical direction; the high end of the support inclined rod 220 is connected with the bottom of the vertical support rod 210, and the low end is connected with the support column 230, thereby forming an inclined support force; and the support column 230, as the basis of the entire support assembly, transmits the force to the ground, thereby ensuring the stability of the entire structure.

[0120] Preferably, the vertical support rod 210, the support inclined rod 220 and the support column 230 are all high-strength seamless steel pipes, which are connected with each other by welding, thereby effectively ensuring the support strength.

[0121] Preferably, the smoke exhaust fan 110 is a vertical axial flow smoke exhaust fan 110, preferably with an outer diameter of 0.9 m and capable of achieving stepless flow adjustment of 0-35 m3 / s; the bottom of the smoke exhaust fan 110 is provided with three vertical support rods 210 with a height of 2.5 m, and a damping gasket is arranged between the vertical support rod 210 and the smoke exhaust fan 110. Further, the vertical support rod 210 is a high-strength seamless steel pipe.

[0122] Further, the support assembly further comprises a fixed connecting rod 240, one end of the fixed connecting rod 240 is connected with the low end of the support inclined rod 220 and the top of the support column 230, and the other end of the fixed connecting rod 240 is connected with the light-shielding shed 40.

[0123] The fixed connecting rod 240 makes the connection between the support inclined rod 220 and the support column 230 more firm, and also strengthens the connection between the light-shielding shed 40 and the smoke exhaust device. Preferably, the fixed connecting rod 240 is an L-shaped steel plate. The fixed connecting rod 240 and the support column 230 are connected by welding.

[0124] Further, a column stabilizing rod 260 is further included, which is used to reinforce the support column 230. Preferably, the column stabilizing rod 260 is an L-shaped steel plate.

[0125] Further, the support inclined rods 220 and the support columns 230 are oppositely arranged on two sides of the sunshade 40, and the intermediate connecting rods 250 are arranged between the two support inclined rods 220 to enhance the overall structural strength.

[0126] Preferably, the outlet of the horizontal section 123 is provided with a first insect screen (not shown in the figure). The first insect screen preferably adopts a 20-40 mesh insect screen, and the main function of the first insect screen is to block insects from entering the smoke flue 120, effectively avoiding the insects breeding or causing blockage in the smoke flue 120, and prolonging the service life of the smoke exhaust fan 110.

[0127] Preferably, the horizontal section 123 is further provided with a water drain hole 124 at one end close to the first insect screen, and the outlet of the water drain hole 124 is provided with a second insect screen (not shown in the figure). In order to prevent rainwater from entering the smoke flue 120 through the first insect screen, a water drain groove with a width of 5 cm is arranged at a distance of 50 cm from the first insect screen, and the second insect screen is arranged at the bottom of the water drain groove, preferably a 20-40 mesh insect screen.

[0128] Further, the first vertical section 121 is in the shape of a prism with a small upper part and a large lower part. The wall material of the prism-shaped first vertical section 121 is preferably 2-3 mm stainless steel, the lower part of the prism-shaped first vertical section 121 has a cross-sectional size of 3*3 m, and the upper part has a cross-sectional size of 1*1 m. The lower part of the prism-shaped first vertical section 121 is embedded in the sunshade.

[0129] The above is only the preferred embodiment of the present application, and does not limit the protection scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and the drawings, or direct or indirect application in other related technical fields, are also included in the protection scope of the present application.

Claims

1. A method for smoke exhaust design of a canopy with restricted boundaries adjacent to a tunnel, characterized in that, The method comprises the following steps: S1, obtaining a critical smoke exhaust amount of a smoke exhaust system of a target tunnel section; wherein the target tunnel section comprises an upstream tunnel section, a sunshade section and a downstream tunnel section connected in sequence, the smoke exhaust system comprises a smoke exhaust component for exhausting part of pollutants from the inside of the sunshade section to the outside of the sunshade section and a fan-shaped smoke baffle matched with the shape of the sunshade section, the smoke exhaust component and the fan-shaped smoke baffle are arranged one by one, and the fan-shaped smoke baffle is arranged downstream of the corresponding smoke exhaust component; S2, determining an optimal smoke blocking height of the fan-shaped smoke baffle according to the critical smoke exhaust amount; S3, obtaining a rated smoke exhaust amount of each smoke exhaust component, and determining the number of smoke exhaust components according to the critical smoke exhaust amount and the rated smoke exhaust amount, and configuring the smoke exhaust system according to the number of smoke exhaust components and the optimal smoke blocking height of the fan-shaped smoke baffle; The step S1 specifically comprises the following steps: S11, establishing a tunnel three-dimensional model for the target tunnel section; S12, obtaining a cross-flow ratio of the tunnel three-dimensional model under different smoke exhaust amounts of the smoke exhaust system; wherein the cross-flow ratio is the ratio of the average concentration of the target pollutant at the downstream tunnel entrance section to the average concentration of the target pollutant at the upstream tunnel exit section, and is used to quantify the degree of cross-flow of the target pollutant from the upstream tunnel to the downstream tunnel; S13, sequentially performing curve fitting on the cross-flow ratios corresponding to different smoke exhaust amounts to obtain a cross-flow ratio-smoke exhaust amount curve; S14, obtaining a node smoke exhaust amount corresponding to an inflection point of the curve according to the cross-flow ratio-smoke exhaust amount curve, and taking the node smoke exhaust amount as the critical smoke exhaust amount; The step S2 specifically comprises the following steps: S21, using the formula dimensionless critical exhaust smoke rate ; wherein, critical exhaust smoke rate, critical wind speed for tunnel fire, tunnel cross-sectional area; S22, using the formula Determining the dimensionless optimal smoke dam height ; S23, using the formula Determining the optimal smoke blocking height of the fan-shaped smoke baffle ; wherein, The tunnel net height.

2. The smoke management design method for a limited perimeter of a canopy tunnel according to claim 1, wherein, The step S3 further comprises the following steps: S31, after starting the smoke exhaust system, fixing the optimal smoke blocking height , obtaining the channeling ratio of the three-dimensional model of the tunnel under different smoke exhaust capacities of the smoke exhaust system ; S32, fixing the critical exhaust smoke amount , obtaining the tunnel three-dimensional model under different smoke blocking heights ;​ S33, establish with mathematical model; S34, determining the actual crossflow ratio of the tunnel three-dimensional model under actual different smoke exhaust volumes and actual different smoke screen heights according to the mathematical model and the mathematical model determines the actual crossflow ratio of the tunnel three-dimensional model under actual different smoke exhaust volumes and actual different smoke screen heights ; S35, determining the actual crossflow ratio according to the actual crossflow ratio Determining the number of fans to be added to the downstream tunnel.

3. The smoke control design method for a canopy with restricted boundaries and abutting tunnels of claim 2, wherein, The step S31 obtains the tunnel three-dimensional model under different smoke exhaust rates of the smoke exhaust system Specifically includes the following steps: Using formula Determine the actual smoke exhaust volume of the smoke exhaust system. ;in, For the first The exhaust duct velocity of each smoke exhaust component The cross-sectional area of ​​the smoke exhaust duct; wherein, each smoke exhaust component includes a smoke exhaust fan and a smoke exhaust duct, the smoke exhaust duct runs through the shading canopy and is connected to the internal space of the shading canopy, the smoke exhaust fan is located in the smoke exhaust duct to exhaust the smoke inside the shading canopy to the outside of the shading canopy through the smoke exhaust duct; Using the formula to determine the dimensionless critical exhaust flow rate ; The formula determines the tunnel three-dimensional model under different smoke exhaust capacity of the smoke exhaust system .

4. The smoke management design method for a canopy-limited boundary with an abutment tunnel of claim 2, wherein, The mathematical model of the step S33 is specifically: 。 5. The smoke management design method for a restricted perimeter of a canopy tunnel, as defined in claim 2, wherein, The step S34 specifically comprises the following steps: The formula is The actual channeling ratios of the tunnel three-dimensional model under actual different smoke exhaust volumes and actual different smoke screen heights are determined .

6. The smoke management design method for a limited perimeter awning tunnel of claim 5, wherein, The step S35 specifically comprises the following steps: The formula is The number of fans to be added in the downstream tunnel is determined; wherein, The required air volume for diluting the tunnel's cross-flow pollutant; The pollutant emission of the upstream tunnel, The standard atmospheric pressure, The atmospheric pressure of the tunnel site, The standard air temperature, The summer air temperature of the tunnel site, The air volume of a single fan, The total pressure efficiency of the fan, The number of fans to be added in the downstream tunnel.

7. The smoke management design method for a canopy-limited boundary with an abutment tunnel of claim 2, wherein, Each smoke exhaust component further comprises a movable smoke blocking component, the movable smoke blocking component is connected with the fan-shaped smoke baffle, and the movable smoke blocking component comprises a roller shutter door, and the opening area of the roller shutter door is adjustably arranged.

8. The smoke management design method for a limited perimeter awning tunnel as defined in Claim 7, wherein, The step S35 further comprises the following steps: S41, when there is no trapped person upstream of the sunshade section, controlling the roller shutter door of any one smoke exhaust component to be below the road surface to completely block the spread of smoke to the downstream tunnel; S42, when the personnel in the downstream tunnel have completed evacuation, retracting the roller shutter door, and opening all the fans of the upstream tunnel and the downstream tunnel until the environment in the upstream tunnel and the downstream tunnel reaches a normal state; S43, closing all the smoke exhaust components.

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