Study on the distribution of sulfur-bearing formations in the Sichuan Basin and its damage to tunnel engineering

Abstract

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.