---on behalf of contractor---
Contractor encountered a shear zone in a rock tunnel in mica schist.
The TBM sank in the sheared material composed primarily of clay.
The conditions are illustrated below.
The contractor requested us to investigate if a differing site condition (DSC)
Upon examination of the exploratory core, we found a section of the core, in the vicinity of the
shear zone encountered, to consist of broken rock, with most of the core missing, and
having an RQD=10%. In our opinion, the conditions encountered were to be
CONTRACTOR DID NOT PURSUE A DSC