seattle, wa - tunneling short course

Seattle, WA www.soilfreeze.comSHORING * GROUNDWATER CONTROL * ENVIRONMENTAL

Haiku is one of the most important forms of traditional Japanese poetry.

Haiku is:

a 17-syllable verse form

consisting of three metrical units of 5, 7, and 5 syllables.

Haiku’s are easy

But sometimes they don’t make sense

Refrigerator

“While most of the elements of the Brightwater project are on schedule, I am extremely concerned about the construction delays on the remaining two-mile segment of the outflow tunnel”

Dow Constantine – King County Executive

• $1.8 Billion, five year Mega project• 13 miles of 17.5’ diameter tunnel, 114 acre facility• Shaft Freezing, break-in/break-out freezing, TBM rescue

History of Ground Freezing

• Ground freezing techniques were used by German scientist F. Hermann Poetsch, in 1883.

• It was first used in America by Chapin Mine Company in Iron Mountain, where freezing was performed to a depth of 100 feet.

• Over the years, the mining industry refined Ground Freezing techniques to successfully complete thousands of shafts all over the world. Some shafts over 2,000 feet deep.

• In the 1900’s freezing expanded into heavy civil construction helping complete many huge projects including: the Grand Coulee dam, the Chunnel, and Boston’s Big Dig.

• Freezing became know as “the method to use when all other methods failed”.

• Why? Because Freezing nearly always worked but the cost was prohibitive.

How Ground Freezing Works

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Manifolds and Freeze Pipes

Before Freezedown During Freezedown

- Size ranges from 20 to 500 tons of chilling capacity. Sized to fit each project.

- Brine is chilled as it passes over baffles in specially designed chambers

- Primary Refrigerant is R507

- Highly automated and very reliable

Electric Chiller Units

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- Brine and ground temperatures at multiple depths are monitored and recorded daily.

- Chillers controlled remotely.

- Remotely monitored via internet connection.

Instrumentation & Monitoring

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-10-505

10152025303540455055606570

0 1 2 3 4 5 6 7 8 9 10

Te

mp

era

ture

[°F

]

Elapsed Time Since Start of Freezing (2-1-2016) [week]

CP-32, Surface Temperature Pipe: T-6 (Temp vs Time)

T6: 58'bgs

T6: 66'bgs

Frozen Soil Wall Formation

Freeze Pipes

Frozen Soil

Impermeable Soil Layer

Groundwater

How Groundwater Cut-off is achieved

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Zone Freeze Technology (Patented)

Structural Shoring System

Frozen Soil

FullExcavation

3” Diameter Steel Pipes

Profile View

Cutoff Layer

Ground Freezing Engineering/Analysis

Temp/W

Plaxis 2D & 3D

●All shoring designs are stamped by a licensed engineer

Soils Analysis

I

Bottom Of Excavation 22’ BGS

45’ BGS (Bottom of Freeze)

SAND

GRAVEL

SILTCLAY

Thermal Analysis

Design and Analysis

“Ground Freezing is utilized in extremely difficult conditions where no other excavation support is feasible, and where cost is usually not a factor.” Kennedy/Jenks Consultants

“The freezing method is remarkably versatile and, with ingenuity, it can be adapted to a great many project conditions.” Dr. Kamran M. Nemati, Professor in Construction Management and Civil

Engineering at the University of Washington

U.S. Environmental Protection Agency (EPA) - Frozen soil barriers are “environmentally benign” and have significant advantages over “conventional containment systems using steel, concrete, slurry walls, or grout curtains” and offer “extremely low maintenance costs, allowing continued use for extended periods”. EPA Site Technology Program, (7th edition, p. 202).

Department of Energy (DOE) - “Frozen soil can eliminate groundwater flow paths” and “the potential is great.” (Scientific Ecology Group, Inc. for Martin Marietta Energy Systems, Document STD-R-00-01)

Freezing to provide groundwater control and excavation support for shaft sinking remains the primary application. In fact, for deep shafts, no better method has yet been established. (The Constructor, Civil Engineering Publication)

- Effective in all soil types (sand, gravel, silt, clay and peat or a mix soil condition)

Advantages

* HKIE Civil Division International Conference 2012iCiD: innovation and Creativity of infrastructure Developments for Quality Cities

High Certainty of Uniformity

Advantages

Advantages

Adaptable

Eco-Conscious

Conventional Shoring

• Dewatering System

• Electrical Power

• Water Treatment Cost

• Water Disposal Cost

• Contaminates

Freeze Shoring

Freezing For the Tunneling Industry

Frozen Soil

23 ft

Freezing For the Tunneling Industry

Freezing For the Tunneling Industry

Freezing For the Tunneling Industry

Freezing For the Tunneling Industry

Freezing For the Tunneling Industry

Soil Freezing for Effective Stabilization for TBM Rescues

Case Study:

Brightwater Regional Waste Water Treatment Plant

• $1.8 Billion, five year Mega project• Located in King & Snohomish Counties, Washington• 13 miles of 17.5’ diameter tunnel, 114 acre facility• Four contracts for Tunneling, Three Joint Venture Contractors

“While most of the elements of the Brightwater project are on schedule, I am extremely concerned about the construction delays on the remaining two-mile segment of the outflow tunnel”

Dow Constantine – King County Executive

The Fix

• Modify receiving shaft to become a launch shaft

• Modify and re-launch Elizabeth

• Stabilize Soil in front of and around the stuck Rainier TBM

• Completely “gut” Rainier including cutter face

• Drive Elizabeth over two miles to Intercept Rainier’s tunnel alignment

• Drive Elizabeth into the empty shell of Rainier

BT3 Junction

Obstacles to Overcome• Stuck under residential neighborhood• 330’ deep, 7 Bar pressure• Geometry involved with freezing around TBM• Electrical power (no 480 volt)• Difficult / disturbed soil conditions

Project Location

BT3 Junction FreezingFreezing Around TBM to Remove Cutter

TBM @ 315’

GW @ 120’

Freeze Pipe Installation

In-tunnel Drilling to Install Freeze Pipes

Figure 5. Elevation plot of thermal results near BT3 face with 4 freeze pipes activated below TBM

Main bearing Removal

Cutterhead Dismantling

Frozen Soil

Fingers Crossed

Hole Through

Success