1. Anonymous (1979) Classification of rocks and soils for engineering geological mapping. Part I: Rock and soil materials. Bull Int Assoc Eng Geol 19:364–371
2. Babendererde L (2003) Problems of TBMs in water bearing ground. In: Proceedings of Summer school 2003 on Rational Tunneling. University of Innsbruck, pp 20
3. Ball RPA, Young DY, Isaacson J, Champa J, Gause C (2009) Research in soil conditioning for EPB tunneling through difficult soils. In: Almeraris G, Mariucci B (eds) Rapid excavation and tunneling conference (RETC). Las Vegas, USA, pp 320–333
4. Bell FG (2000) Engineering properties of soils and rocks. Blackwell Science Ltd., Oxford
5. Bruland A (1998) Hard rock tunnel boring: drillability test methods. Project report 13A-98, NTNU Trondheim