Deterioration of actual railway tunnel lining in southwest China:Geotechnical, material structural

摘要

Two tunnels, locating at Kunming section of Cheng-kun railway line were selected as candidates of durability investigation. This work is conducted by structural analysis, geotechnical and material investigation, and etc. Based on the procurable material related to tunnel design, construction and inspection from the local railway maintenance bureau, structural analysis is performed with commercial analysis program. Hazards of structural defect and soundness of tunnel lining were evaluated before restoration engineering. Concrete core drilling is conducted. The remains of chemical reaction are collected for XRD and SEM+EDS spectrum analysis. Water near the coring pot is sampled for chemical analysis. The serial investigations show that the structural defaults lead to serious deterioration of lining in material and other aspects as well. The chocked groundwater immerses the rock, leading to degradation of the rock and increase of water pressure. The vulnerability of drainage system and the absence of waterproof result in groundwater flowing out of the collapsed drainage system and moving along local or permeable inhomogeneities of concrete.