Geological Hazards During Construction and Operation of Shallow Subway Stations and Tunnels by the Example of the Kharkiv Metro (1968–2018)

Abstract

Scientific, technical and practical problems have been considered in relation to geological hazards during construction and operation of metro objects such as shallow subway stations and tunnels. Analysis of five decades of the experience of construction and subsequent operation of the Kharkiv metro in rough engineering and geological conditions by construction of tunnels at shallow depths under the existing urban development allowed detecting and systematizing a set of the most essential adverse conditions, processes and phenomena. The main geological hazards are related to the expansion of quicksands, possibility of “flotation” of the underground structures, barrage effect, subsidence of the soil body by long-term dewatering, undermining of the built-in territories and difficulties by tunneling in technogenic fill-up grounds when crossing ravines and gullies. Most problems occur in the territories with a high groundwater level: geological risks in these areas increase, and serious incidents occur by sudden adverse changes of hydrodynamic conditions. Zones of high, medium and low geological hazards have been identified. Geological hazards have been defined at the section planned for extension of the metro line, for which calculations of the affluent value were made based on the barrage effect of tunnels on the groundwater flow. Taking into account the possibility of emergence of engineering and geological processes and prevention of their development provides safe and reliable construction and operation of shallow metro systems. The obtained results of evaluation of geological hazards can be used by designing and construction of underground objects in similar conditions.