Mapping Tunneling-Induced Uneven Ground Subsidence Using Sentinel-1 SAR Interferometry: A Twin-Tunnel Case Study of Downtown Los Angeles, USA

Synthetic Aperture Radar (SAR) interferometry is a formidable technique to monitor surface deformation with millimeter detection resolution. This study applies the Persistent Scatter-Interferometric (PSInSARTM) measure ground subsidence related twin-tunnel excavation in downtown Los Angeles, USA. The PSInSARTM suitable for urban settings because areas have strong reflectors. twin tunnels Angeles were excavated beneath densely urbanized area variable overburden depths. In practice, tunneling-induced settlement dominantly vertical. vertical rate this derived by combining Line of Sight (LOS) velocities obtained from SAR images both ascending and descending satellite orbits. Local uneven settlements up approximately 12 mm/year along tunnel alignment are observed within allowable threshold. No severe damages aboveground structures reported. Furthermore, movements mapped one year before construction indicate that no concentrated pre-existed. A Machine Learning (ML)-based permutation feature importance method used parametric identify dominant factors associated twin-tunneling induced subsidence. Six parameters selected conduct study, including thickness, i.e., thickness artificial fill alluvium soils above springline, distance between two centerlines, depth building height, tunnel, groundwater level. Results analysis contributing factor, followed height. Two parameters, level, play lesser essential roles than others. addition, geological profile provides comprehension unevenly distributed settlements, which geologically sensitive more thick soils, low depth, high levels.