Calculation method and application of tunnel side key smoke exhaust limited wind speed

Abstract

The invention relates to a calculation method and application of a tunnel side key smoke exhaust limited wind speed. The calculation method comprises the following specific steps: determining definition of the limited wind speed uc and influence factors, and establishing a relational expression between the limited wind speed uc and the influence factors; determining a basic dimension, and establishing a dimension relational expression between the limited wind speed uc and the influence factors; determining basic physical quantities, obtaining dimensionless items of influence factors according to the pi theorem, and obtaining a dimensionless calculation formula of the limited wind speed uc through derivation; obtaining the numerical value of the smoke counter-current length L of the fire under different working conditions through numerical simulation, obtaining the limited wind speed through the smoke counter-current length, drawing the simulation result into a scatter diagram, and determining the influence of influence factors on the limited wind speed uc; and performing data fitting on the results to obtain the value of each unknown coefficient in the dimensionless relational expression, and further establishing a calculation formula of the dimensionless limited wind speed uc. The method has the beneficial effects that the method is simple, is suitable for different tunnels, has great influence on efficient utilization of the tunnel smoke exhaust capacity, and provides guidance for fire smoke control and fire rescue of side key smoke exhaust tunnels.

Description

technical field [0001] The invention relates to the technical field of tunnel fire smoke control, in particular to a calculation method and application of a limited wind speed for key smoke exhaust at the side of a tunnel. Background technique [0002] Fire is one of the biggest risks to tunnel operations. Due to the narrow and closed characteristics of the tunnel, the tunnel has a unique spatial structure and fire characteristics compared with ordinary ground buildings. Once a fire breaks out in the tunnel, the smoke cannot be discharged in time, which can easily cause suffocation or poisoning, and secondary damage will occur if the vehicles in the tunnel leave too late, resulting in a major catastrophic accident involving mass death and mass injury. Controlling the limited wind speed is conducive to the efficient use of the smoke exhaust capacity of the tunnel, and the control of the smoke within a certain range to ensure personnel evacuation and rescue. [0003] Restric...

AI Technical Summary

Problems solved by technology

The current research mainly explores the calculation method of the critical wind speed. The critical wind speed is the longitudinal wind speed that just makes the smoke counterflow length zero, which can ensure that there is no smoke upstream of the fire source. However, the critical wind speed is used to control the spread of smoke. On the one hand, due to the critical wind speed Theoretically, it is greater than the limited wind speed, so the smoke cannot be exhausted to the nearest upstream smoke outlet; The heat release rate of the fire source is related to the distance between the non-dimensional smoke outlet and the fire source. Therefore, the longitudinal wind speed predicted by the critical wind speed model controls the counterflow of smoke, which is still affected by the change of smoke discharge.

[0004] At present, most of the existing limited wind speed calculation methods are aimed at the situation where the smoke exhaust outlet is located at the top of the tunnel. The limited wind speed is determined according to the ratio of the length of the counterflow of the smoke to the tunnel height. The mouth is located on the side wall of the tunnel. Compared with the smoke exhaust at the top, the stress state and motion state of the smoke have changed at this time. There is no calculation method for the limited wind speed of the tunnel fire in the side key smoke exhaust mode at home and abroad.

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