PI | |
Project Type | Experimental |
Natural Hazard Type(s) | Flood, Earthquake |
Facilities | |
Awards | Natural Hazards Engineering Research Infrastructure | 2037900 |
Keywords | Levee, Mobile Shaker, DAS, distributed acoustic sensing, Imaging |
On 21-22 October 2021, the NHERI@UTexas experimental facility, in collaboration with the University of California, Berkeley, the U.S. Army Corps of Engineers (USACE), and the Engineer Research and Development Center (ERDC) hosted a workshop on Fiber Optic Distributed Acoustic Sensing (DAS) for Infrastructure Engineering and Subsurface Imaging. Day 1 of the workshop was held at the LSU Center for River Studies from 9:00 am to 5:30 pm CST. Videos of presentations from Day 1 of the workshop are available at https://utexas.designsafe-ci.org/workshops/. Day 2 of the workshop included a field DAS imaging demonstration on a section of Mississippi River levee in Black Hawk, Louisiana, where approximately 2 km of fiber optic cable had been installed in both surface and borehole arrays as a means to image the levee at high spatial resolution and monitor seepage. This section of levee is of particular interest to the USACE because severe seepage was detected during a flood event in 2015. A sand boil on the landward side of the levee prompted an emergency retrofit. The USACE stopped the flow through the sand boil by placing a line of deep relief wells along the landward toe of the levee and covering the surface expression with a gravel pad. The purpose of the DAS imaging campaign is to assess the extent of internal erosion at the site and evaluate the use of DAS for such applications. This project houses a publicly available DAS dataset from the workshop. More specifically, it contains DAS time histories at approximately 1-m channel separation from a 240-m long section of fiber optic cable buried in a shallow trench at the site. The DAS data was collected with an OptaSense ODH4+ interrogator using a 2-m gauge length. The seismic source for the data acquisition was the NHERI@UTexas Thumper vibroseis truck, which was used to generate vertical dynamic excitation in the form of 12-second long chirps over the frequency range of 5-200 Hz. DAS data acquired from 15 different shot points located parallel to the alignment of the cable are provided. Additional details about the experiment and data collected maybe found in the README file accompanying the dataset.