Investigation of the geological and hydrogeological environment with relation to metro system construction in Jinan, China

Jinan City is located in Eastern China, where porous water and karst water are well developed. The geographic position, geological environment, and terrain of Jinan provide many springs, most of which are distributed in urban areas. When metro lines are constructed in Jinan, six types of stratum combinations are typically encountered. Dewatering needs to be considered to avoid the occurrence of water-inrushing, quicksand and piping hazards, which can change the groundwater seepage environment and reduce spring discharge. In addition, the existence of metro lines can block the recharge channels of karst water. The effects of a metro system are felt on springs in three zones: shallowly buried areas of limestone, deeply buried areas of limestone and spring discharge areas. This paper proposes countermeasures to mitigate the impacts of metro lines on groundwater seepage and to protect springs. These measures include waterproof curtains, dewatering on demand, groundwater head monitoring, artificial recharge, tunnel waterproofing, and groundwater flow path systems.