'geotechnical, tunnel boring, differing site conditions'

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GeoConSol
Geotechnical & Tunnel Consultants

A consultant is a universal observer who can look at a problem outside the environment in which the problem came to be, thereby creating a solution that was never possible before.  Fernando Flores

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A-Misrepresentations
B-Type 1 or 2?
C-Jacked Pipe Failure
D-Top of Rock
E-PI Litigation Support
F-Geotech Assessment
G-Microtunneling Hard/Soft
H-Machine Failure
I-Boulders-Tunnel Boring
J-Boulders-Microtunneling
K-Plowing Utilities
L-Rock Socket Overrun
M-Bored Tunnel Inflow
N-Rock Comminution
O-Sub-Std TBM Performance
P-Bored Tunnel-Shear Zone
Q-Disputes Resolution
R-Problem Proj. Completion
S-Bored Tunnel Overbreak
T-Auger Sampling Problems
U-Bored Tunnel Delay
V-Hoe Ram - Failure to Rely
Peter J. Tarkoy
tunnel, boring, performance, shear, zone, differing, site, condition, consulting

DSC-Shear Zone
---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) was encountered.

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 anticiapted.


CONTRACTOR DID NOT PURSUE A DSC
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