Construction Ventilation Optimization And Risk Management Of Large Section Gas Tunnel

In recent years,with the deepening of the development of the Midwest and “The Belt and Road”national strategy,China’s infrastructure construction ushered in a hitherto unknown development opportunity,tunnel engineering as an important part of the infrastructure construction,gradually moving from the plains to the mountain ridge area,and as large section tunnel cross the mountainous region,there will be inevitable tunnel passing through existing coal and gas occurrence area,and the gas as a significant risk of tunnel engineering construction safety,usually need to design a reasonable ventilation scheme and risk management system to eliminate.In this paper,I take Chongqing city Liang Zhong highway control project-comity tunnel project as the research object,through theoretical calculation,numerical analysis and risk management scheme design combined with the design of large section gas tunnel construction ventilation optimization and risk management system,the main research contents and results of this article are as follows:(1)Based on the basic theory of gas tunnel construction ventilation,the purpose and principle of gas tunnel construction ventilation are summarized.Summary of gas tunnel ventilation ventilation and ventilation methods,summed up the corresponding basis,and on this basis,combined with the Chongqing tunnel through the calculation of actual yield,ventilation and wind construction,designing the gas tunnel ventilation scheme.(2)According to the actual section parameters of comity tunnel,secleting a research section of 200 m,establish a three-dimensional analysis of the corresponding calculation model and mesh it by CFD pretreatment module of ICEM Fluent software,then using Fluent solver for numerical simulation,getting the distribution and diffusion regularity of gas tunnel airflow and gas concentration distribution and diffusion regularity.(3)Analysis of factors that influence the gas concentration field of gas in the tunnel,the main factors that affect the tunnel gas concentration field is:gas emission quantity,construction ventilation amount,tube diameter,air duct outlet from the hanging position,the distance of the tunnel face.Based on the influence factors,the influence of various factors on the gas concentration field in the high gas tunnel was studied.(4)For a specific gas tunnel,gas emission quantity and construction ventilation amount have been identified,emission and construction ventilation in the gas duct layout scheme for the optimization of it only need to consider three factors:the cylinder diameter,cylinder and cylinder hanging position air from the tunnel face distance.Choose the gas concentration in stable state of face center for the characterization factor to tube diameter,and outlet duct,air duct hanging position from the tunnel face distance factors,through orthogonal design and corresponding by range analysis and variance analysis of two kinds of means to determine the order of importance for three factors influencing the stability of tunnel face gas concentration the air duct and determine the best layout scheme optimization.(5)Starting from the basic process of gas tunnel risk management,considering from four aspects of recognition named basic risk factors and management factors from human factors,natural factors to see who can lead to large section tunnel with gas explosion accident,and analysis the corresponding risk assessment with the method of the analytic hierarchy process and the accident tree,so we we can find the main factors leading to gas tunnel explosion accident,finally we can do the ultimate risk response and the corresponding risk control by means of ventilation optimization.