Investigation of Tunnel Collapse Mechanisms through Numerical Analysis

Abstract

In this study, tunnel excavations were introduced in two typical ground conditions found in unstable urban areas, and the corresponding tunnel collapse mechanisms were investigated using numerical analysis. The case studies of tunnel collapse in weathered rock and uncemented sandy soil layers revealed that a plastic area extended across the entire tunnel section from the tunnel shoulder to the ground surface. The development of the displacement vector indicated the possibility of a tunnel ceiling depression occurring around the plastic area. The numerical analysis results suggest that tunnel excavation, which accelerates bedrock weathering or induces ground relaxation following groundwater introduction, can lead to the collapse of uncemented sandy soils.