Injection of a Ventilation Tower of an Underwater Road Tunnel Using Cement and Chemical Grouts

This paper presents the monitoring and the grouting works of an immersed road tunnel. As this underground structure is almost 30 years old, groundwater has gradually damaged and penetrated the concrete, bringing water problems in the winter as the water forms into ice that can fall on cars or damage electrical equipment. To understand the problem related to water infiltration and find solutions, instruments were installed to monitor the movement of a horizontal construction joint and exploratory drilling was conducted in the concrete ventilation tower structure. These investigations led to choosing two solutions: a first phase of cement grouting and a second phase of chemical grouting were carried out between 1998 and 1999. From the different available observation locations, both grouting methods gave satisfactory results for the stopping of water leakages in the ventilation towers.