Soil conditioning of volcanic soil using low environmental impact agents
EPB technology is an effective tunnelling method in urban areas when surface settlements must be avoided by controlling face stability and underground water inflow. Soil conditioning plays a major role on this aspect, although the use of additives should be limited encouraging the use of low environmental impact products. This paper analyses the conditioning process of the EPB used for the excavation of the Airport Metro line in Naples. The geological environment is quite challenging for this type of technology, and it includes weathered ignimbrite with finer volcanic ash. To evaluate the feasibility of using EPB technology in this volcanic debris, slump tests and extraction tests have been carried out on the mass conditioned with innovative and more sustainable additives. The results have shown a good attitude of the conditioned material to be used in an EPB excavation, also confirmed by the good behaviour of this material during the extraction test through a screw conveyor.