Fiber Optic Monitoring of Sand Boil Development

Researchers: Andrew Yeskoo

Client/Owner: US Army Corps of Engineers ERDC and Vicksburg District

Technologies: Distributed Fiber Optic Sensing

The UC Berkeley team designed and installed an array of fiber optic monitoring points in an area of past and suspected future sand boil development along a section of levee on the Mississippi River. The project included the installation of four approximately 100ā€™ deep vertical monitoring points to observe vertical displacements and temperature changes that may be correlated with the increase in hydraulic pressure associated with sand boils. To minimize the number of cables installed in the borehole, a specialized turn-around detail was designed to allow for a single strain cable to be joined with a single temperature cable in a ā€œUā€ shape configuration. All four borehole monitoring points are networked together and terminate in a single location where a fiber optic analyzer developed by UC Berkeley for the project is set up to take automated readings. The system is designed to take readings of strain and temperature across the monitored section of the levee, detecting any potential temperature or strain changes in the subsurface. Monitoring at the site is ongoing and is scheduled to continue through 2022 and will hopefully inform future work on levee safety.