Formation mechanism of ground fissure at Beijing Capital International Airport revealed by high-resolution InSAR and numerical modelling

Abstract

A NE-SW trending ground fissure that extends for 13 km was first discovered at Beijing Capital International Airport (BCIA) in 1985. There are many factors that influenced its formation mechanism, including the activity of the Shunyi-Liangxiang (SL) fault, land subsidence and human engineering activities. Fine-scale surface deformation at BCIA was obtained by interferometric synthetic aperture radar (InSAR), using 27 TerraSAR-X data with a 3 m resolution, to better understand the failure phenomenon and formation mechanism of the ground fissure. Spatially, the SL fault intersects runway 36R obliquely at the airport, and the fissure forms along the fault. A zone of subsidence was observed on the footwall (northwest side) of the SL fault; however, the ground fissure along the SL fault dips towards the southeast. The InSAR subsidence rate profiles show a rate difference of 9–17 mm/yr across the ground fissure, consistent with the deformation characteristics of concrete surface fractures at BCIA. Constrained by the subsidence rate obtained by InSAR, the discrete element method (DEM) was applied to simulate the failure process of runway 36R. The formation mechanism of the ground fissure was revealed: the SE-dipping SL normal fault is the most important geological factor controlling the boundary of subsidence and extension of the ground fissure; the regional subsidence on the footwall of the SL fault is the main triggering factor in the development of the ground fissure; the damage of the concrete surface induced localized uplift; and the decrease in soil strength in the fault zone has led to localized subsidence along the ground fissure.