|
|
|
|
 Back to Projects
|
|
|
|
Project:
|
|
Drop Shaft, South Bay Ocean Outfall
|
|
Location:
|
|
San Diego, California
|
|
Client:
|
|
Traylor Brothers/Obayashi Joint Venture
|
|
Description:
|
|
Ground freezing was determined to be the only method technically feasible for excavation support
of a 46-foot diameter shaft, extending 200 feet in sandy, unstable soils. A frozen earth wall 300
feet deep and over 12 feet thick was required for both bottom stability and structural integrity
to overcome very high earth and hydrostatic pressures.
Large zones of boulders in the subsurface soils required large, specialized drilling rigs to advance
the freeze pipes and maintain a high degree of vertical alignment. Gyroscopically guided mud motors
were used to steer the freeze pipes down in certain locations.
The ground freezing system, coupled with a grouting program had to overcome the effects of high
groundwater velocities resulting from an ancient buried river valley.
An innovative application of High Density Polyethylene pipe was used for the freeze pipe configuration
at the tunnel eye, facilitating a safe, water-tight tunnel exit from the shaft.
A standby ground freezing design for freezing the face of the tunnel boring machine was required if
unstable soil conditions occurred as far as two miles out into the Pacific Ocean.
|
|
|
|
|
Please enter your e-mail address below to be notified of product / information updates!
|
|
|
|
|
|
|
|
|
|
|
|
|
|
