Research on the Disaster - causing Mechanism and Countermeasures of Tunnel Harmful Gas in Central Sichuan

Research purposes: With the continuous construction of tunnel projects in Suining and Ziyang areas of central Sichuan, the problem of harmful gases has gradually become prominent. In order to reduce the risk of harmful gases in tunnels in Suining and Ziyang areas of central Sichuan, this paper studies the geological and oil and gas characteristics of the area based on structural data, stratigraphic data, and oil and gas geological data combined with tunnel exploration and harmful gas testing results, and explores the disaster -causing mechanism of harmful gases in tunnels in the region. Research conclusions: ( 1 ) The lower multiple oil and gas reservoirs are abundant in the Suining - Ziyang area of Sichuan, and there is a rich source of harmful gases in tunnels. (2) The main mode of harmful gas transportation in the study area is through joint fissures, with stratigraphic continuity as a minor factor. ( 3 ) The anticline in the study area is wide and gentle, and its core has been eroded. The structural storage of harmful gases in the anticline is poor, and the storage space for harmful gases is mainly composed of joint fissures and sandstones, while mudstone serves as the cover layer for harmful gases. (4) Harmful gas enrichment is generally poor in the area, characterized by low concentrations of harmful gases in most tested boreholes and strong randomness in the distribution of harmful gases. (5) The research results can provide reference for the investigation and design of harmful gases in tunnels in similar strata and structural areas of the Sichuan Basin. © 2023 Editorial Department of Journal of Railway Engineering Society. All rights reserved.