Control Countermeasures And Distribution Of Carbon Monoxide Gas During Extra-long Tunnel Construction

Our country which is the mountain kingdom, hilly and mountainous area accounts is about two-thirds of total land area. More and more highways are faced with mountains of the block. Highway construction needs to apply tunnel technique, so more and more extra-long tunnel appear. If the tunneling distance is very long, then the problem of ventilation would limit the construction progress. According to the operation environment of extra-long tunnel, by using theoretical analysis, field test and numerical simulatin method, Control Countermeasures and Distribution of Carbon Monoxide Gas were analyzed. The main research results are as follows.(1) In order to accurately assess the impact of environmental quality on the tunnel construction process, the dust concentration, the CO concentration, the environmental noise, the environment vibration, heat environment and the light environment were selected as the six evaluation indexes, on the basis of analyzing influencing factors of the environmental quality during tunnel construction. Then, evaluation index system of environmental quality during tunnel construction was established. The results show that the extenics evaluation model can reflect each indicator, which rise independent indicators of environmental quality analysis to systematic environmental assessment. And the model can reflect the state of the construction environment more objectively.(2) The wind flow field is complexity and distribution of CO concentration has uncertainty. Combining with the actual situation of a tunnel construction, the numerical analysis model was built. Numerical simulation was carried out by using computational fluid dynamics software Fluent to simulate after blasting harmful gas diffusion and concentration field distribution of harmful gas in the working area. It can be summed up as follows:the vortex area retards the exhaust of CO from the working face. A peak of CO concentration is in the central position of eddy current area. The discharge process of CO gas along the tunnel can be regarded as "moving" and "diffusing". Contrast real-time monitoring data and simulation results show that the simulation results are effective and reliable.(3) The tunnel ventilation time was used as the characterization factor, and the influence factors were selected to design the orthogonal test. By analyzing the importance of each factor, Suggestions of how to optimize design are given. The simulation verifys its validity. According to the process with poor air environment, In order to quantitatively forecast continuous work time of COHb reaching the blood dangerous concentration, the numerical results were applied in the CFK equation. Finally it can provide the theoretical basis for drawing up ventilation management measures in the tunnel slag process.