GIS-based Settlement Risk Assessment and its Effect on Surface Structures: A Case Study for the Tabriz Metro—line 1

摘要

Abstract Ground deformations caused by tunnelling operation may compromise existing infrastructure and structures. Depending on the state of the buildings, and the amount of settlement that will occur, damage to the buildings could be induced. It is therefore a good practice to conduct a settlement risk assessment. The study presented herein provides information about settlement and damage induced due to metro tunnel excavation operations. During the excavation phase of the tunnel within the Tabriz alluvium (sand to fine-grained sediments with considerable pore pressure), the settlements that caused damages to the surface urban facilities and buildings were monitored. The presented study focuses on the effect of surface settlement that are induced due to tunnel excavation and provides risk-ability maps using a Geographic Information System to represent the degree of ground deformations which vary from very high-risk to very low-risk susceptibility zones. The risk class for each building is determined by a combination of the vulnerability of the structure to settlement-induced damage (which isexpressed as the building class) and the actual chance of settlement-induced damage (which is expressed as the damage category). In order to identify possible damage to each building, the settlements should be linked to building deformations and provide risk maps. The risk maps were prepared based on the severity of the building’s vulnerability, subsidence value, and structure durability classes which was implemented by the finite element code provided by the Plaxis software. According to the results, the buildings and structures located along the tunnel excavation route have suffered structural damage due to the severity of the subsidence.