The sulfur-bearing formations in the Sichuan Basin are widely distributed, whose harmful gases have caused serious threat to tunnel engineering. Based on the existing data collected, the research shows that the main sulfur-bearing formations in the Sichuan Basin include the Triassic Leikoupo Formation, Jialingjiang Formation, and Feixianguan Formation, the Permian Longtan Formation, the Carboniferous Huanglong Formation, the Silurian, the Cambrian and the Sinian. Sulfur-containing gas is closely related to the active degree of tectonic movement in the area where it is located, and is mainly manifested in three aspects: the generation, migration and storage of sulfur-containing gas. According to the tectonic distribution, depth and concentration of the Sichuan basin, the hazard grade of the sulfur-bearing strata in the basin was classified. The Permian Longtan Formation and the Carboniferous Huanglong Formation can be divided into Level IV sulfur-containing strata. The Triassic Leikoupo Formation, Jialingjiang Formation, Feixianguan Formation, and the Silurian strata can be divided into Level III sulfur-containing strata, meanwhile the Cambrian and Sinian strata can be divided into Grade II. The result of sulphur-bearing strata hazard classification was applied to the Yuelongmen Tunnel of Chenglan Railway, and the on-site inspection results were consistent with the application analysis results.

四川盆地含硫地层分布广泛，有害气体对隧道工程造成严重威胁。根据现有资料，研究表明，四川盆地主要含硫地层包括三叠系雷口坡组、嘉陵江组、飞仙关组、二叠系龙潭组、石炭系黄龙组、志留系、寒武系和震旦人。含硫气与其所在地区的构造运动活跃程度密切相关，主要表现在含硫气的生成、运移和储存三个方面。根据四川盆地的构造分布、深度和集中度，对盆地含硫地层进行危险等级划分。二叠系龙潭组和石炭系黄龙组可划分为Ⅳ级含硫地层。三叠系雷口坡组、嘉陵江组、飞仙关组和志留系可分为Ⅲ级含硫地层，寒武系和震旦系可分为Ⅱ级。将含硫地层危害分类结果应用于成兰铁路越龙门隧道，现场检查结果与应用分析结果一致。同时寒武系和震旦系可划分为Ⅱ级。将含硫地层危害分类结果应用于成兰铁路越龙门隧道，现场检查结果与应用分析结果一致。同时寒武系和震旦系可划分为Ⅱ级。将含硫地层危害分类结果应用于成兰铁路越龙门隧道，现场检查结果与应用分析结果一致。