Cutter Soil Mixing (CSM), a deep soil mixing method, was used to improve the soil conditions at a jobsite in Lantau Island (Hong Kong), acting as deep guide wall and trench support for the further diaphragm wall works, on a project that required the construction of two ventilation shafts for tunnels built by Tunnel Boring Machine technology. The geological profile of the reclamation area where the works were carried was composed by a layer of fill (sand) and 15 to 20 meters thick layer of very low cohesion, underconsolidated, marine deposits (soft clay), varying from virtually 0 kPa at the top to 30 kPa at the bottom, at the top of an alluvium deposits layer.It was the marine deposits layer that required to be treated otherwise there was the risk of its intrusion into the excavated diaphragm wall panels and trench collapse.
The paper describes the necessary approach to apply Cutter Soil Mixing under the specific site conditions and discusses also the results obtained from tests carried on site.
Subjects: Cutter Soil Mixing, Marine Deposits, Under-consolidated Clays; Ground Improvement
Author: Sandro Gomes, Joao Nunes, Franz-Werner Gerressen and Thomas Vohs
Publisher: DFI, EFFC