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201-8 Mapping Ground Subsidence Caused by Excavation of a Rail Crossover Cavern and Twin Tunnels in Downtown Los Angeles Using Multi-sensor, Multi-platform InSAR

Session: Land Surface Subsidence—Processes, Impacts, and Ongoing Challenges

Presenting Author:

Wendy Zhou

Authors:

Zhou, Wendy Wei¹, Wnuk, Kendall², Liu, Linan³r> (1) Colorado School of Mines, Golden, CO, USA, (2) Universities Space Research Association, Washington, D.C., USA, (3) China University of Geosciences (Beijing), Beijing, China,

Abstract:

This presentation discusses two case studies in downtown Los Angeles: (1) subsidence linked to the excavation of a subway station and rail crossover cavern; and (2) ground subsidence related to twin-tunnel construction. In the first case, surface deformation measurements above the excavation were obtained through InSAR time-series analyses of data from sensors operating at different wavelengths, including the C-band Sentinel-1, X-band COSMO-SkyMed, and L-band UAVSAR. Data from these satellite and airborne SAR sensors revealed deformation around the 2nd Street and Broadway Subway Station and the nearby rail crossover cavern, with maximum vertical displacement reaching 2.5 cm and horizontal displacement 1.7 cm. In the second case study, ground subsidence associated with twin-tunnel excavation was mapped using the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSARTM) technique. The vertical deformation rate in this study is derived by combining Line-of-Sight (LOS) deformation velocities obtained from Sentinel-1 SAR images in both ascending and descending satellite orbits. Local and uneven settlements of up to approximately 12 mm/year were observed along the tunnel alignment. Furthermore, a Machine Learning (ML)-based permutation feature-importance method is used in a parametric study to identify dominant factors associated with twin-tunneling-induced uneven ground subsidence. Among the six parameters selected for the parametric study, overburden thickness, i.e., the thickness of artificial fill and alluvium soils above the tunnel springlines, is the dominant factor, followed by the distance between tunnel centerlines, depth to the tunnel springlines, and building height. Two parameters, the distance to the tunnel and the groundwater level, play lesser roles than the others.

Mapping Ground Subsidence Caused by Excavation of a Rail Crossover Cavern and Twin Tunnels in Downtown Los Angeles Using Multi-sensor, Multi-platform InSAR

Description

Session Format: Oral

Presentation Date: 10/13/2026

Presentation Start Time: 09:50 AM

Presentation Room: CCC, 111

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