Distribution and genesis of ground fissures in the Beijing Area, China: a case study

Beijing is one of the Chinese cities currently affected by ground fissure, where we identified seven mapped ground fissure zones and conducted geological and geotechnical characterizations. Notably, stronger ground fissure activity exists in the Tongzhou and Gaoliying areas. These ground fissures are rapidly expanding, causing damage to roads, pipelines, and urban infrastructure. To ascertain their probable origin and physical properties, we conducted surveys, excavations, and drillings, and used various geophysical techniques. Our findings indicate that the ground fissures in Beijing typically trend northeast, with strike angles ranging from 30° to 50°, reach a maximum length of over 25 km, and affect an area up to 160 m wide. Most of the fissures were aligned with the underlying active faults, and as the depth increased, there was a corresponding vertical displacement. Surface displacement can range from slow gradual movements to rapid shifts, leading to abrupt ground failure and severe damage in nearby urban areas. Based on our analysis, we deduced that regional tectonic movement established the geological conditions necessary for the occurrence of ground fissure zones and that fault activities played a pivotal role in their formation. However, the primary cause of the escalating physical displacement is the progressive extraction of groundwater. In summary, the origin, overall features, and extent of the fissures in Beijing were comparable to those observed in other locations worldwide. Consequently, effective mitigation measures involve avoidance or implementation of suitable engineering designs.