Structure of karst water system and hydrological circulation characteristics of Lianghu Tunnel in Wuhan

Abstract

Among the underlake tunnels in the urban areas, the Lianghu Tunnel in Wuhan is the longest one of China and the largest one in the world.The East Lake part of this tunnel passes through the karst area. Identifying its karst water system structure is of great significance to the safety of tunnel construction and operation.To reveal the structure of the karst water system and the characteristics of the water cycle in the area, a comprehensive method of geological-hydrogeological investigation and hydrogeochemical analysis was conducted to characterize the boundary of the karst aquifer system, summarize the karst development law, identify the source of cave sediments, analyze the hydraulic connection between karst water, pore water and surface water, as well as discuss the hydrological circulation model of the karst water system.The results show that the study area can be divided into two karst aquifer systems, the north and the south.The karst development degree is stronger in the northern karst aquifer system than that in the southern karst aquifer system but has a unified hydraulic connection through the fault zone. The cave sediments mainly derived from Quaternary residual layers and the weathering of the cave surrounding rock.The pore water in the Quaternary alluvial-pluvial aquifer has a weak hydraulic connection with karst water, while the pore water in the Quaternary residual aquifer has a close hydraulic connection with karst water.The karst water system structures of underlake tunnels were characterized by a variety of techniques and methods, which helps the risk assessment of water inrush and the safe construction of tunnel engineering.

Keywords

• lianghu tunnel
• karst water system
• structural characteristics
• hydrological circulation