Simulation Study on the Effect of Forced Ventilation in Tunnel under Single-Head Drilling and Blasting

Pu, Qingsong; Luo, Yi; Huang, Junhong; Zhu, Yingwei; Hu, Shaohua; Pei, Chenhao; Guang, Zhang; Li, Xinping

doi:10.1155/2020/8857947

Cited by 6 publications

(3 citation statements)

References 25 publications

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“…These harmful gases are mainly CO, and the concentration must be reduced to below the safe concentration standard before proceeding with the next construction operation [1][2][3]. Ventilation is one of the most effective methods for removing harmful gases [4]. In order to quickly eliminate pollutants and accelerate construction progress, the optimization of the ventilation scheme is extremely important [5,6].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Tunnel Ventilation Considering the Air Leakage Mechanism of a Ventilation Duct

Chang,

Chai,

Ren

et al. 2024

Applied Sciences

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Ventilation problems are critical in tunnel engineering, and the loss of air volume in ventilation ducts is generally estimated using empirical methods. The air volume calculation makes it difficult to meet the accuracy requirements, resulting in resource waste or insufficient air supply. In this study, the forced ventilation system of the tunnel under construction was investigated based on the computational fluid dynamics method. The mechanism of air leakage on airflow distribution and pollutant transport in the tunnel is determined. Air leakage reduces the distribution peak of pollutants and effectively accelerates the emission of harmful gases. However, this effect decreases with distance from the air duct inlet. Through the calculation results of nearly one hundred models, it is found that the air leakage of the duct can be fitted by logarithmic function and verified by empirical equation. The matching degree between the fitting function of the model and the empirical equation depends on the length of the tunnel. On this basis, the calculation formula of effective air volume near the working face is derived. This study can be applied to the ventilation engineering of the tunnel under construction and provide a theoretical basis for the calculation of the effective air supply.

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Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Tunnel Ventilation Considering the Air Leakage Mechanism of a Ventilation Duct

Chang,

Chai,

Ren

et al. 2024

Applied Sciences

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“…In terms of CO transport law in tunnels, Harris and other scholars, − through on-site monitoring of CO concentration data in tunnels, analyzed the pattern of change of the monitoring data and derived the distribution of CO in tunnels over time; Torno and other scholars, − using the hydrodynamics software to establish a reasonable roadway tunnel model, defined the smoke that is blown out of the gun after the blasting time, analyzed the distribution of gun smoke under different blasting conditions, and predicted when workers could enter the workplace after blasting; Vorontsov and others − established a model of gun smoke diffusion in the roadway, concluded that the gun smoke diffusion law was significantly affected by the wind flow, and derived the calculation formula of the CO dispersion coefficient of the tunneling roadway; Zhou and others − analyzed the basic theory of mine ventilation and made a systematic research on the aspects of the mine ventilation system and the local ventilation of the mine and quarry; and so on. In addition, in-depth research has also been conducted on the ventilation design of the quarry, wind flow, and the transportation law of gas; Zhong’an and others − numerically simulated the soot flow after blasting in the tunnel and gave an optimal ventilation scheme for the actual engineering situation, which provided a reference basis for the numerical simulation of soot ventilation in the tunnel.…”

Section: Introductionmentioning

confidence: 99%

CO Diffusion Study and Spatial and Temporal Variation Modeling during the Construction Period of the Plateau Railroad Tunnel

Liu,

Zhao,

Wang

et al. 2023

ACS Omega

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In order to investigate the diffusion law of CO gas in the vicinity of the tunnel boring face of the plateau long tunnel, to improve the efficiency of tunnel smoke exhaust, and to derive the spatial-temporal variation model of CO concentration for predicting the concentration of CO at different times and in different cross sections under specific environments, a CO diffusion model of a tunnel in Yunnan was established by using Ansys Fluent Fluid Simulation Software, and the CO transport characteristics under different conditions were simulated by taking the ventilation time, wind speed, and location of the air ducts as the influencing factors. The results show that the wind flows from the mouth of the wind pipe after the wind speed decreases, the diffusion area increases and arrives at the face of the direction of the rebound in the jet stream of new wind, and the return wind under the joint action of the vortex produced obviously, to reach the wind pipe mouth after the tunnel wind flow field, basically tends to stabilize. When the wind pipe mouth was arranged in the arch waist, 20 m away from the boring face, the inlet wind speed was 9 m/s and the ventilation time was 30 min; the CO concentration in the tunnel was reduced to below the maximum allowable concentration value. Moreover, the concentration of CO in the tunnel at the moment of 15 min of ventilation has a nonlinear positive correlation with the change of distance L from the boring face, while at the cross section of the air outlet of the wind pipe L = 20 m, the ventilation time is from 1 to 30 min and the concentration of CO at the cross section has a nonlinear decreasing trend with the ventilation time, which can be deduced according to the different space–time change models.

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“…Other studies have also been developed in underground coal mines to study blasting fume dilution using auxiliary ventilation systems [ 8 ]. Pu et al [ 9 ] constructed a 3D CFD numerical model to simulate the diffusion process of toxic gases after blasting in a 47 m 2 railway tunnel using forced ventilation. They used different ventilation duct layout modes and different tunnel construction methods, such as full-face excavation and the top-heading-and-benching approach.…”

Section: Introductionmentioning

confidence: 99%

Concentration, Propagation and Dilution of Toxic Gases in Underground Excavations under Different Ventilation Modes

Menéndez¹,

Merlé

Oro

et al. 2022

IJERPH

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The drill-and-blast method is widely used for the excavation of hard rock tunnels. Toxic gases such as carbon monoxide and nitrogen oxides are released immediately after blasting by the detonation of explosives. To provide a safe working environment, the concentration of noxious gases must be reduced below the threshold limit value according to health and safety regulations. In this paper, one-dimensional mathematical models and three-dimensional CFD numerical simulations were conducted to analyze the concentration, propagation and dilution of the blasting fumes under different operating conditions. Forced, exhaust and mixed ventilation modes were compared to determine the safe re-entry times after blasting in a 200 m-long tunnel excavated using the top-heading-and-benching method. Based on the numerical simulations, carbon monoxide was the most critical gas, as it required a longer ventilation time to reduce its concentration below the threshold limit value. The safe re-entry time reached 480 s under the typical forced ventilation mode, but was reduced to 155 s when a mixed ventilation system was used after blasting, reducing the operating costs. The reduction of the re-entry time represents a significant improvement in the excavation cycle. In addition, the results obtained show that 1D models can be used to preliminary analyze the migration of toxic gases. However, to reliably determine the safe re-entry times, 3D numerical models should be developed. Finally, to verify the accuracy of the CFD results, field measurements were carried out in a railway tunnel using gas sensors. In general, good agreements were obtained between the 3D numerical simulations and the measured values.

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Simulation Study on the Effect of Forced Ventilation in Tunnel under Single-Head Drilling and Blasting

Cited by 6 publications

References 25 publications

Numerical Simulation of Tunnel Ventilation Considering the Air Leakage Mechanism of a Ventilation Duct

Numerical Simulation of Tunnel Ventilation Considering the Air Leakage Mechanism of a Ventilation Duct

CO Diffusion Study and Spatial and Temporal Variation Modeling during the Construction Period of the Plateau Railroad Tunnel

Concentration, Propagation and Dilution of Toxic Gases in Underground Excavations under Different Ventilation Modes

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