Water inrush hazards in the Chaoyang tunnel, Guizhou, China: A preliminary investigation

Abstract

This paper reports on a water inrush hazard, which occurred during the construction of the Chaoyang tunnel in Libo County, Guizhou Province, China. On 10 June 2018, a continuous water inflow of about 57 thousand m3 of water within 40 min took place at the tunnel excavation face, resulting in three casualties. The objectives of this study are to investigate and discuss the water inrush process of this atypical case. Further, an inclusive description of the implemented emergency responses will be provided. The principal causes of this tunneling incident include the karst geological condition at the construction field, hydraulic conductivity induced by the connection between karst water system and surface water body, and effects of excavation and precipitation. Moreover, based on a preliminary investigation and analysis, three main control measures to overcome similar incidents in the future are proposed: (1) Performing "water inrush risk grading" in areas prone to water inrush; (2) undertaking comprehensive geological forecast for a synthetic analysis; and (3) employing a monitoring system during the construction, and educating workers on self-protection skills. These effective management measures are bound to benefit underground engineering constructions with regard to water inrush risks.