Experimental device and method for determining the minimum air duct area of ​​actual engineering tunnels

Abstract

The present invention relates to an experimental device and method for determining the minimum air duct area of ​​an actual engineering tunnel. The experimental device includes a tunnel experimental model, a fan, an air duct plate and an adjusting mechanism; wherein the air duct plate is assembled with the tunnel experimental model in a sliding sealed connection manner, and the adjusting mechanism is arranged directly below the air duct plate, and is used to support and adjust the height of the air duct plate to achieve a change in the air duct area. The experimental device with adjustable air duct area of ​​the present invention can be used to simulate the ventilation and smoke exhaust conditions in the ventilation system of an actual engineering tunnel, creating conditions for determining the minimum air duct area in the ventilation system of an actual engineering tunnel. On the other hand, the experimental device and method for determining the minimum air duct area of ​​an actual engineering tunnel described in the present invention can provide a theoretical basis for the structural design of the existing tunnel ventilation system, and can also be used to verify the feasibility of the existing tunnel ventilation scheme, providing a possibility for reducing the initial investment and construction risks of tunnel engineering construction.

Description

Technical Field

[0001] The invention relates to the field of tunnel ventilation, and in particular to an experimental device and method for determining a minimum air duct area of ​​an actual engineering tunnel. Background Art

[0002] Since the International Tunnel Association proposed the initiative of "vigorously developing underground space and starting a new cave-dwelling era for mankind", the development and utilization of underground space has been actively responded to by countries around the world as a major measure to solve the three major problems of population, environment and resources. In particular, the construction of traffic tunnels can not only alleviate the pressure of urban and rural traffic and solve the restrictions on traffic trunk lines across rivers and seas, but also shorten the line mileage and reduce the impact on the surrounding environment and people's production and life. However, with the development of economy and society, especially the rapid development of tunnel construction technology, tunnel construction has become more and more complicated. While bringing convenience to people's production and life, it has also led to many new technical problems, such as long-distance tunnel disaster prevention ventilation, fire escape and evacuation and rescue. Among them, the tunnel ventilation system has always been one of the factors affecting the feasibility of tunnel engineering construction plans. If the proposed tunnel ventilation system is too complicated, especially when the air duct area set at the top of the tunnel is too large, it will lead to an increase in the initial investment and construction risk of tunnel engineering construction. Therefore, how to reasonably design the air duct area has always been the focus and difficulty of tunnel ventilation system research.

[0003] At present, there are many methods to study tunnel ventilation and smoke exhaust systems, mainly including engineering analogy, numerical simulation, theoretical analysis and model experiments. Among them, Wang Yaqiong and others applied for the invention patent of "a tunnel ventilation model test system", researched and developed a test conditioning chassis, which can calculate the static pressure according to the real-time measured wind speed and wind pressure values; Cui Xinghua and others applied for the invention patent of "an adjustable slope corridor ventilation model device", which can find out the slope that can quickly remove smoke, so as to make appropriate adjustments to the angle of the pipeline used in actual construction; Wu Yikai and others applied for "an adjustable cross channel of a tunnel ventilation model", so that the angle between the main channel and the cross channel can be adjusted, so as to reduce energy loss, improve ventilation efficiency and simulation when the cross channel and the main channel are at a certain angle.

[0004] In summary, the above studies mainly focus on test calculations, ventilation energy saving, rapid smoke exhaust and other issues in model experiments, and do not propose how to reasonably design the duct area (i.e., the cross-sectional area formed by the duct plate and the top space) in the tunnel ventilation system to reduce construction investment and construction difficulty while meeting the feasibility of the ventilation scheme. Summary of the invention

[0005] In order to solve the problem that the tunnel top air duct area is too large or the design is unreasonable in the existing tunnel ventilation system and tunnel ventilation system construction plan, the present invention provides an experimental device and method for determining the minimum air duct area in the actual engineering tunnel ventilation system. The device and method can provide a theoretical basis for the design of the tunnel ventilation system, and can also be used to verify the feasibility of the tunnel ventilation plan, providing a possibility for reducing the initial investment and construction risk of tunnel engineering construction.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: an experimental device for determining the minimum air duct area of ​​an actual engineering tunnel, the experimental device comprising a tunnel experimental model and a fan for ventilation inside the tunnel experimental model, wherein:

[0007] The tunnel experimental model is scaled down in proportion with reference to the actual engineering tunnel;

[0008] The tunnel experimental model is composed of a tunnel body and a tunnel vault, and a wind duct plate connected to the tunnel body in a sliding and sealing manner is provided under the tunnel vault;

[0009] An adjusting mechanism for supporting and adjusting the height of the air duct plate is provided below the air duct plate. The cross-sectional area of ​​the sealed space formed by the air duct plate and the tunnel test model portion above is the air duct area, which can change with the change of the height of the air duct plate.

[0010] Furthermore, the tunnel experimental model is scaled down in proportion with reference to the longitudinal length and cross-sectional circumference of an actual engineering tunnel.

[0011] Furthermore, the adjusting mechanism is a hydraulic jack; the fan is a variable frequency axial flow fan, which includes a supply fan arranged on one side of the top of the tunnel test model and an exhaust fan arranged on the other side of the top of the tunnel test model.

[0012] Preferably, the tunnel test model is made of high-transmittance and bendable engineering materials; the air duct plate is made of cold-rolled steel plate, and the thickness of the air duct plate is 2-5 mm.

[0013] The present invention also provides a method for determining the minimum air duct area in an actual engineering tunnel ventilation system, comprising the following steps:

[0014] S1, taking the actual engineering tunnel ventilation system as a reference, scale down any of the experimental devices described in the above schemes;

[0015] S2, determine the fan air volume Q1 in the actual engineering tunnel ventilation system, according to the formula Calculate the air volume Q2 of the fan installed on one side of the top of the tunnel test model in the tunnel test model;

[0016] S3, changing the height of the air duct plate by means of an adjustment mechanism disposed below the air duct plate in the tunnel test model, thereby changing the air duct area, and recording the fan residual pressure P2 under the corresponding air duct area;

[0017] S4, according to the fan residual pressure P2 corresponding to different air duct areas recorded in step S3, calculate the actual fan residual pressure P1 in the actual engineering tunnel ventilation system, and the calculation formula is as follows:

[0018]

[0019] Among them, P1 is the fan residual pressure in the actual engineering tunnel ventilation system, unit Pa; P2 is the fan residual pressure in the tunnel test model, unit Pa; λ1 is the resistance coefficient along the actual engineering tunnel, dimensionless constant; λ2 is the resistance coefficient along the tunnel test model, dimensionless constant; n1 is the longitudinal length ratio of the actual engineering tunnel and the tunnel test model, dimensionless constant; n2 is the cross-sectional perimeter ratio of the actual engineering tunnel and the tunnel test model, dimensionless constant;

[0020] S5, based on the calculation result obtained in step S4, draw a relationship curve between different fan residual pressures P1 and the corresponding duct area in the actual engineering tunnel ventilation system, and associate it with the set fan characteristic curve to determine the duct area under the fan air volume Q1, which is the minimum duct area that needs to be determined in the actual engineering tunnel ventilation system.

[0021] Furthermore, in step S4, the value of λ1 is determined by the material properties of the actual engineering tunnel; the value of λ2 is determined by the material properties of the tunnel experimental model; in step S5, the duct area in the actual engineering tunnel ventilation system corresponding to different fan residual pressures P1 is calculated based on the corresponding duct area in the tunnel experimental model.

[0022] Compared with the prior art, the present invention has the following advantages and effects:

[0023] 1. The experimental device for determining the minimum air duct area of ​​an actual engineering tunnel described in the present invention comprises a tunnel test model, a fan, an air duct plate and an adjustment mechanism; wherein the air duct plate is assembled with the tunnel test model in a sliding sealed connection manner, and the adjustment mechanism is arranged directly below the air duct plate, and is used to support and adjust the height of the air duct plate, so as to achieve a change in the cross-sectional area of ​​the sealed space formed by the air duct plate and the upper tunnel test model, that is, a change in the air duct area. This experimental device with adjustable air duct area can be used to simulate the ventilation and smoke exhaust conditions in the ventilation system of an actual engineering tunnel, creating conditions for determining the minimum air duct area in the ventilation system of an actual engineering tunnel.

[0024] 2. The experimental device for determining the minimum air duct area of ​​an actual engineering tunnel described in the present invention has a simple structure, ingenious design, easy installation, and is easy to simulate and operate. The air duct area can be accurately adjusted through a controller; the experimental method for determining the minimum air duct area of ​​an actual engineering tunnel described in the present invention is based on the fan characteristic curve, can effectively avoid tedious theoretical calculations, and quickly and efficiently determine the minimum air duct area corresponding to the actual engineering tunnel ventilation system.

[0025] 3. The experimental device and method for determining the minimum air duct area of ​​an actual engineering tunnel described in the present invention can provide a theoretical basis for the structural design of the existing tunnel ventilation system, and can also be used to verify the feasibility of the existing tunnel ventilation scheme, providing a possibility for reducing the initial investment and construction risks of tunnel engineering construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 This is a schematic diagram of the structure of an experimental device for determining the minimum air duct area in an actual engineering tunnel ventilation system as described in Example 1 of the present invention.

[0028] Figure 2 This is a cross-sectional view of an experimental device for determining the minimum air duct area in an actual engineering tunnel ventilation system as described in Example 1 of the present invention.

[0029] Figure 3 This is a schematic diagram of adjusting the air duct area using the experimental device described in Example 1 of the present invention.

[0030] Figure 4 This is a comparison chart of the relationship between different air duct areas and fan residual pressures in the tunnel test model in the method described in Example 2 of the present invention.

[0031] Figure 5 This is a comparison diagram of the relationship curve between different air duct areas and fan residual pressure in an actual engineering tunnel and the fan characteristic curve in the method described in Example 2 of the present invention.

[0032] Explanation of reference numbers: 1. Tunnel experimental model; 2. Supply fan; 3. Exhaust fan; 4. Adjustment mechanism; 5. Duct plate; 6. Duct area. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with embodiments. The following embodiments are for explanation of the present invention but the present invention is not limited to the following embodiments.

[0034] Example 1: Figures 1 to 3 As shown, an experimental device for determining the minimum air duct area of ​​an actual engineering tunnel, the experimental device includes a tunnel experimental model 1 and a fan for internal ventilation of the tunnel experimental model 1;

[0035] Wherein: the tunnel experimental model 1 is scaled down in proportion with reference to the actual engineering tunnel; the experimental model 1 is composed of a tunnel body and a tunnel vault, a duct plate 5 is provided below the tunnel vault and is slidingly and sealingly connected to the tunnel body, an adjustment mechanism 4 for supporting and adjusting the height of the duct plate 5 is provided below the duct plate 5, and the cross-sectional area of ​​the sealed space enclosed by the duct plate 5 and the upper tunnel experimental model part is the duct area 6, which can change with the change of the height of the duct plate 5.

[0036] Specifically, in this embodiment 1, the tunnel test model 1 is obtained by scaling down in proportion with reference to the longitudinal length and cross-sectional circumference of an actual engineering tunnel; the adjusting mechanism 4 is a hydraulic jack, and the fan is a variable frequency axial flow fan, which respectively includes a blower 2 arranged on one side of the top of the tunnel test model 1 and an exhaust fan 3 arranged on the other side of the top of the tunnel test model 1.

[0037] As a preferred implementation, in this Example 1, the tunnel test model 1 is made of high-transmittance and bendable engineering materials; the air duct plate 5 is made of cold-rolled steel plate, and the thickness of the air duct plate 5 is 2-5 mm, preferably 2 mm.

[0038] Example 2: Figures 3 to 5 As shown, a method for determining the minimum air duct area in an actual engineering tunnel ventilation system specifically includes the following steps:

[0039] S1, with reference to the actual engineering tunnel ventilation system, the tunnel test model 1 described in Example 1 is scaled down in proportion; specifically, the longitudinal length of the actual engineering tunnel is set to L1 (unit: m), and the cross-sectional perimeter is set to U1 (unit: m); the longitudinal length of the tunnel test model is set to L2 (unit: m), and the cross-sectional perimeter is set to U2 (unit: m); according to the scaling ratio, the following is obtained:

[0040] L1=n1·L2 (1)

[0041] U1=n2·U2 (2)

[0042] S2, determine the fan air volume Q1 in the actual engineering tunnel ventilation system, according to the formula Calculate the air volume Q2 of the air blower 2 disposed on one side of the top of the tunnel test model 1 in the tunnel test model 1;

[0043] S3, changing the height of the air duct plate 5 by the adjustment mechanism 4 disposed below the air duct plate 5 in the tunnel test model, thereby achieving a change in the air duct area 6, and recording the fan residual pressure P2 under the corresponding air duct area 6;

[0044] S4, according to the fan residual pressure P2 corresponding to the different air duct areas 6 recorded in step S3, calculate the actual fan residual pressure P1 in the actual engineering tunnel ventilation system, the calculation method is as follows:

[0045] (a) To establish a 1:1 speed scale:

[0046] υ1=υ2 (3)

[0047] In the above formula, υ1 is the actual engineering wind speed, unit: m / s; υ2 is the tunnel test model wind speed, unit: m / s;

[0048] (b) Based on the calculation formula of hydraulic diameter d and the calculation formula of cross-sectional area S and cross-sectional perimeter U:

[0049]

[0050]

[0051] In the above formula, d is the hydraulic diameter, unit: m; C is a constant, a dimensionless constant; S is the cross-sectional area of ​​the tunnel, unit: m 2 ; U is the perimeter of the section;

[0052] (c) According to the calculation formula of the resistance along the way:

[0053]

[0054] Wherein, P is the fan residual pressure, unit: Pa; λ is the resistance coefficient along the way; L is the longitudinal length of the tunnel, unit: m; ρ is the gas density; υ is the air speed, unit: m / s;

[0055] d) Combining formulas (1), (2), (3), (4), (5), (6) and (7), we can derive formula (8) for calculating the fan residual pressure P1 in the actual engineering tunnel ventilation system:

[0056]

[0057]

[0058] Among them, P1 is the fan residual pressure in the actual engineering tunnel ventilation system, unit Pa; P2 is the fan residual pressure in the tunnel test model, unit Pa; λ1 is the resistance coefficient along the actual engineering tunnel, dimensionless constant; λ2 is the resistance coefficient along the tunnel test model, dimensionless constant; n1 is the longitudinal length ratio of the actual engineering tunnel and the tunnel test model, dimensionless constant; n2 is the cross-sectional perimeter ratio of the actual engineering tunnel and the tunnel test model, dimensionless constant;

[0059] S5, based on the calculation result obtained in step S4, draw a relationship curve between different fan residual pressures P1 and the corresponding duct area in the actual engineering tunnel ventilation system, and associate it with the set fan characteristic curve to determine the duct area under the fan air volume Q1, which is the minimum duct area that needs to be determined in the actual engineering tunnel ventilation system.

[0060] Among them, in step S4, λ1 is determined by the material properties of the actual engineering tunnel; λ2 is determined by the material properties of the tunnel experimental model; the actual air duct area corresponding to different fan residual pressures P1 is calculated from the corresponding air duct area in the tunnel experimental model.

[0061] Specifically, the experimental device described in Example 1 and the experimental method described in Example 2 of the present invention are used to design the following test examples:

[0062] Take a certain project as an example, the tunnel length is 2000 (m), the cross-sectional area is 9.8 (m 2 ). According to the similarity principle, a tunnel experimental model was established with a length of 20 (m) and a cross-sectional area of ​​0.098 (m 2 ), according to formulas (1), (2), and (5), we can calculate that: n1 = 1:100, n2 = 1:10.

[0063] The resistance coefficient along the actual tunnel project is λ1=0.022. The tunnel experimental model is made of high-transmittance, flexible PMMA material, and the resistance coefficient along the experimental model is λ2=0.015.

[0064] According to the similarity theory, the air volume Q1=60m in the actual engineering tunnel ventilation system is calculated. 3 / s, air volume of the tunnel experimental model fan

[0065] Before conducting quantitative analysis, the following data were obtained through experiments: duct area and fan pressure P2. The experimental data are as follows:

[0066] (a) In the tunnel test model, the height of the air duct plate is changed by adjusting the mechanism, thereby changing the air duct area; the recorded data are as follows:

[0067] The areas of the air ducts are {0.06, 0.061, 0.062, 0.063, 0.064, 0.065, 0.066, 0.067, 0.068, 0.069, 0.07, 0.071, 0.072, 0.073, 0.074, 0.075, 0.076, 0.077, 0.078, 0.079, 0.008}, unit: m 2 ;

[0068] (b) The fan pressure P2 corresponding to each of the above-mentioned air duct areas is {180.4, 173.3, 166.5, 160.1, 154.1, 148.4, 142.9, 137.8, 132.9, 128.3, 123.9, 119.7, 115.7, 111.9, 108.3, 104.8, 101.5, 98.5, 95.4, 92.5, 89.7}, unit: Pa; wherein the fan pressure P2 can be directly read from the fan system.

[0069] The above experimental data are processed and obtained Figure 4 The relationship curve between the fan residual pressure P2 and the air duct area is shown in the figure; the variable of the ordinate is the fan residual pressure P2 in the tunnel experimental model ventilation system, unit: Pa, and the abscissa is the air duct area, unit: m 2 .

[0070] Finally, the fan residual pressure P1 of the actual engineering tunnel ventilation system corresponding to the fan residual pressure P2 is calculated using formula (8), and the duct area in the experimental model corresponding to the fan residual pressure P2 is converted into the duct area in the actual engineering tunnel ventilation system according to the similarity principle, and the relationship curve between different fan residual pressures P1 and the corresponding duct area in the actual engineering tunnel ventilation system is plotted (e.g. Figure 5 and the fan performance fitting curve (as shown in “—□—” in the figure) Figure 5 ) as shown by “—Δ—” in the figure.

[0071] Among them, the fan performance fitting curve is:

[0072] P = -0.0025326548·Q 3 +0.89296077·Q 2 -97.151025·Q+4865.321. Based on the performance curve, the relationship curve between the total resistance of the fan and the fan air volume can be obtained, such as Figure 5 Indicated by “—Δ—”.

[0073] according to Figure 5 The data show that for this project, the minimum duct area is 7.2m 2 .

[0074] In summary, the present invention makes the following conclusions by analyzing specific implementation schemes:

[0075] By adjusting the tunnel test model after the air duct area, the operating parameters Q2 and P2 of the axial flow fan can be directly read, and the minimum air duct area required for the actual engineering tunnel ventilation system corresponding to the model can be calculated; therefore, the present invention proposes a simple and reliable tunnel test model with adjustable air duct area and a calculation method.

[0076] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different. Any equivalent or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. The technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. An experimental device for determining the minimum air duct area of ​​an actual engineering tunnel, characterized in that: The experimental device includes a tunnel experimental model and a fan for ventilation inside the tunnel experimental model, wherein the fan is a variable frequency axial flow fan, wherein: The tunnel experimental model is scaled down in proportion with reference to the actual engineering tunnel; The tunnel experimental model is composed of a tunnel body and a tunnel vault, and a wind duct plate connected to the tunnel body in a sliding and sealing manner is provided under the tunnel vault; An adjustment mechanism for supporting and adjusting the height of the air duct plate is provided below the air duct plate. The cross-sectional area of ​​the sealed space formed by the air duct plate and the tunnel test model above is the air duct area, which can change with the change of the height of the air duct plate. The tunnel experimental model is scaled down in proportion with reference to the longitudinal length and cross-sectional perimeter of an actual engineering tunnel.

2. The experimental device for determining the minimum air duct area of ​​an actual engineering tunnel according to claim 1, characterized in that: The fans include a supply fan respectively arranged on one side of the top of the tunnel test model and an exhaust fan arranged on the other side of the top of the tunnel test model.

3. The experimental device for determining the minimum air duct area of ​​an actual engineering tunnel according to claim 2, characterized in that: The tunnel test model is made of high-transmittance and bendable engineering materials; the air duct plate is made of cold-rolled steel plates, and the thickness of the air duct plate is 2-5 mm.

4. A method for determining the minimum air duct area in an actual engineering tunnel ventilation system, characterized in that: The following steps are involved: S1, with reference to the actual engineering tunnel ventilation system, scale down the experimental device described in any one of claims 1 to 3; S2, determine the fan air volume in the actual engineering tunnel ventilation system Q 1 , according to the formula , calculate the air volume of the fan installed on the top side of the tunnel test model in the tunnel test model Q 2 ; S3, by changing the height of the air duct plate through the adjustment mechanism set under the air duct plate in the tunnel test model, the air duct area is changed, and the fan residual pressure under the corresponding air duct area is recorded. P 2 ; S4, according to the fan residual pressure corresponding to different air duct areas recorded in step S3 P 2 , calculate the actual fan residual pressure in the actual engineering tunnel ventilation system P 1 , the calculation formula is as follows: ； in, P 1 is the fan residual pressure in the actual engineering tunnel ventilation system, unit: Pa; P 2 is the fan residual pressure in the tunnel test model, unit: Pa; λ1 is the resistance coefficient along the actual engineering tunnel, a dimensionless constant; λ2 is the resistance coefficient along the tunnel experimental model, a dimensionless constant; n 1 is the ratio of the longitudinal lengths of the actual engineering tunnel and the tunnel experimental model, a dimensionless constant; n 2 is the ratio of the cross-section perimeter between the actual engineering tunnel and the tunnel experimental model, a dimensionless constant; S5, based on the calculation results obtained in step S4, draw different fan residual pressures P 1 The relationship curve with the air duct area in the corresponding actual engineering tunnel ventilation system is correlated with the set fan characteristic curve to determine the fan air volume Q 1 The air duct area below is the minimum air duct area that needs to be determined in the actual engineering tunnel ventilation system.

5. The method for determining the minimum air duct area in an actual engineering tunnel ventilation system according to claim 4, characterized in that: In step S4, the value of λ1 is determined by the material properties of the actual engineering tunnel; the value of λ2 is determined by the material properties of the tunnel experimental model; in step S5, different fan residual pressures P The duct area in the actual engineering tunnel ventilation system corresponding to 1 is calculated based on the corresponding duct area in the tunnel experimental model.

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