Highlight
Earth Dam and Levee Monitoring Advances
Achievement/Results
The Colorado School of Mines IGERT Smart Dam Team’s research goals are to develop technology needed to change traditional monitoring methods for earth dams and levees into intelligent adaptable systems. Intelligent earth dams and levee systems include continuous ‘health’ monitoring and assessment, with means to adapt to improve performance and/or reliability. Using continuous and wireless sensing and monitoring, intelligent earth dams and levees will assess early onset of internal erosion and other damage due to aging or extreme loading, and will advance 4D (space and time) monitoring systems that fuse together geophysical, geotechnical and sensing data. This team of six graduate trainees and associates has combined their interdisciplinary knowledge from Geology, Geophysics, Civil Engineering, and Computer Science to perform laboratory and field experimentation and to develop unique test hardware.
To successfully achieve team goals, the SmartGeo Smart Dam Team has developed a multi-scale approach to study phenomena from local (micro) to global (macro) scale, as depicted in Figure 1. Previous work in wireless sensor network (WSN) development of combined geophysical sensing techniques is ongoing. New and exciting future field application opportunities have been established by the team members, including time-lapse monitoring of a salt injection tracer test at the Nottingham Dam site (summer 2012), time-lapse monitoring of a planned mitigation pumping program at the Grandby Landslide site (summer 2012), as well as time-lapse AE and SP and LIDAR monitoring of a full-scale levee test facility in the Netherlands (August and September 2012).
At the micro scale in the laboratory, team members have designed and fabricated a laboratory large-diameter rigid cell permeameter (Figure 2) to control load and flow conditions to induce compaction and erosion in earthen materials in order investigate geophysical signals associated with changes in material properties. The team is investigating the size of features the techniques can discern and the sensitivity of the different detection methods. They will use time-lapse monitoring to study what internal erosion looks like as it initiates and other instrumentation to measure flow rate, upstream head level, acoustic emissions (passive seismic), active seismic, and self potential. Team members have also collaborated with US Bureau of Reclamation (USBR) to instrument concentrated flow testing in cracked earth filter materials using wired active and passive seismic and self potential. The ongoing tests are being performed at a test facility referred to as the “Crack Box,” (Figure 3) located at the USBR Hydrodynamics Laboratory on the Denver Federal Center.
At the meso scale, the team has conducted field self potential and electrical resistivity testing at two sites (Figure 4) to characterize subsurface conditions and identify concentrated flow within earthen dams. The team has developed opportunities: 1) to develop and implement a permanent wired time lapse DC resistivity, temperature and SP monitoring system (Figure 5) at an earthen dam structure in Utah, and 2) to instrument a full scale research levee in the Netherlands (Figure 6), that will be built and failed via piping and internal erosion mechanisms at the Ijkdijk research facility, in collaboration with US agency and international partners, 3) monitor settlement within operating earthen dams with airborne and terrestrial lidar and radar. While some opportunites are nacent, many are underway and have active research agreements facilitating collaboration. The enthusiasm private industry has for interdisciplinary research has made collaboration with IGERT particularly enticing. These opportunities are planned for later in 2012.
At the macro scale, team members have conducted time lapse radar monitoring of an active landslide in Colorado, in collaboration with local and federal government agencies and other external university partners (Figure 7). In addition to these efforts, baseline SP, DC resistivity and seismic tomography were carried out across the slide. Near future collaborations and research efforts may include time lapse radar and SP monitoring during a planned mitigation pumping program at the site, with the goal of better characterizing the effectiveness of the dewatering program by monitoring slide movement with radar and developing a time lapse model of the phreatic surface near the pumping well using time lapse SP data inversion.
For hardware development and testing, trainees in collaboration with Dr. Chuck Oden from Earth Science Systems (ESS) are further developing a high-end wireless, precision data acquisition system that supports long-term in-situ geophysical measurements for monitoring structural health of dams and levees. The hardware, currently in its third revision, supports high sampling frequencies and large amounts of in-network data using geophysical inspection techniques like self potential, resistivity, and seismic measurements. In addition to the ESS mote platform being developed, a second WSN mote has been developed utilizing the Arduino Fio platform. This is a very novel yet inexpensive and open-source (non-proprietary) WSN platform that will allow for rapid prototyping, programming,
Address Goals
The research being conducted and results to date have advanced our ability to peer into earth dams and levees to identify potential weak zones (areas of concentrated seepage). This is very critical to prevent future disasters in terms of earth dam and levee failiures (and subsequent flooding).
The interdisciplinary approach that brings six Fellows from four disciplines is creating the next generation of leaders to solve our nation’s critical problem with earth dams and levees.
