ABSTRACT
Arroyo et al: Design of jet grouting for tunnel waterproofing. This paper presents a case history from Barcelona. A new high speed rail tunnel was excavated in quaternary deposits, dominated by paleochannels of water bearing sands and gravel. The high speed rail tunnel was constructed at depths of 6-25 m and passed beneath the still active existing railway lines. Ground water level was at 10-15 m below ground level. Jet grouting was used to mitigate the danger of sudden collapse and inundation, which was the primary risk. (Settlement, if slow, could be tolerated due to an active ballast maintenance programme.) Several jet configurations are considered. The paper focuses on sub-horizontal single fluid pipe canopy and floor slabs configurations, used where vertical access was not available. Details of field trials and other design tools used to successfully construct the tunnel are given in the paper. Figure 1 shows the probabilistic assessment used to verify the continuity of the jet grout canopy-a key design requirement.
