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
microtunneling, differing, site, conditions, microtunnelling, Tarkoy, GeoConSol

MicroTunneling Differing Site Conditions
---on behalf of several contractors---

On a number of projects, micro-tunneling machines embarked into material having extremes of soft hard material interfaces. Line & grade were impossible to maintain. There are solutions to this problem, however, each works within a very limited range of conditions.

1. A microtunnelling alignment was underneath a swamp, however, the soil sampling was performed by the geotechnical engineer from a causeway over the swamp. The soil properties under the causeway were far better because the material had been consolidated. The microtunneling could not maintain line & grade without considerable expense for ground treatment.


2. On Waikiki Beach a micro-tunneling excavation ran into part of the original wood bridge when crossing a buried valley near Waikiki Beach)

  The archive files of the area revealed that here had been a wooden bridge located at the site of the obstruction of the pipe jacking operation.


After long negotiations, the city of Honolulu settled with the contracter based on our analyses showing the obstruction and hard/soft layers representing tidal and coral deposits.