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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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
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
top of rock, rock, overrun, slurry walls, differing site conditions, Tarkoy, GeoConSol

Slurry Rock Socket Overrun DSC
(on behalf of contractor)

The contractor was required to socket 2 ft into rock along the perimeter slurry wall.  In the early stages it was apparent that the rock socketing would be overrun.

When the socketing was completed, we prepared a graphic representation of the slurry walls and respective rock sockets to illustrate anticipated and encountered conditions here below...

The data from the panels was summarized by illustrating the anticipated, anticipated excess, encountered, and encountered excess rock socketing area.  The socketing area was overrun by a factor of 7.5.

The original borings were done using a hollow stem auger.  Refusal of the auger was taken as the top of un-decomposed rock.  The specifications required a 2 ft deep socket of the slurry wall into rock. 

In effect, the rock tools were unable to excavate decomposed rock to the depth of the auger refusal.

The auger refusal was not a viable measure of the top of rock for slurry wall socketing.