| Gas is the product of geological effects. Occurance state of the present coal seam gas is the result of coal-bearing strata affected by complex geoglogy evolution, being controled by synthetical geoglogical effects such as gas generation, migration, conservation conditions. Gas generation, migration, conservation conditions and dynamic phenomenon of coals and gas outburst all result from geological effects. Gas geology laws exist in the cases above. Because Gas geology laws hide in the tunnel monitoring data, it is indispensable to study these data. In order to avoid the occurrence of gas disasters, the present tunnel security technology and management staff should monitor the case of gas during the entire gas tunnel construction. Reinforcing the analysis of gas monitoring data, it will become more initiative to forecast and deal with accidents. Therefore, it is the key to adopt which gas monitoring scheme in tunnels and how to farthest acquire the useful information in the abundance of monitoring data.In this thesis, the causes of high gas density in Zipingpu Tunnel was analyzed, proceeding from the traits of tunnels themselves and a good many factors including gas factors, geology factors and others which affected gas concentration in tunnels. After analyzing the main differences between tunnel construction and mine roadway, network system was established for tunnel gas monitoring. The features of tunnel gas concentration monitoring data and the law features of gas monitoring data were systematically analyzed from multi-angles. It timely forecasted the gas concent??on monitoring data by fuzzy trend prediction technology, means of swinging model and sparse coefficient autoregression model. The main content and achievement in the thesis are as follows:(1) Collected, read and analyzed the updated documents related to the study. Combined with the traits of tunnels themselves and influence factors of tunnel gas, established network system for tunnel gas monitoring.(2) By means of the basic analysis of geology conditions, tunnel engineering and tunnel gas general situation of Zipingpu Tunnel, and combined with the mature gas geoglogy law, especially the influence factors of ccurance state of coal seam gas, in the research of mine roadway, analyzed the causes of high gas in Zipingpu Tunnel.(3) By means of systematic feature analysis of tunnel gas density and gas abnormal range of monitoring data, established monitoring data analysis and classification in three aspects which include the form, the amount and the monitoring point layout.(4) By analysising the characteristics of gas monitoring data of different scenarios (blasting/sampling location/time period /geological background), it may conclude that:â‘ the gas density after bursting is much higher than regular gas density before blasting;â‘¡the gas density characteristics of different sampling locations is different, which is shown by occurrence frequency of abnormal range;â‘¢As a whole there is no clear correlation between occurrence times of gas emission and tunneling length in the same time, but viewed it in segmental way, then the occurrence times of gas emission and tunneling length in the same time shown a positive correlation with different ratio factor;â‘£other than transfinite uniformly distributed in the tunnel, the occurrence frequency of transfinite is different in different geological background section.(5) According to specific geological condition of Zipingpu tunnel, based on mathematical method, the thesis suggested three gas prediction models that contain trend prediction based on fuzzy patter recognition, swing model and sparse coefficient autoregressive model. Through the practical application during Zipingpu tunnel co??uction process, the three types of gas prediction model are proven that can guide the dynamic design and construction, and has a well practicality and maneuverability.
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