The high-performance, compact, and cost-effective Etna2 accelerographs were interconnected to create strong-motion networks for real-time data services such as rapid analysis and notification.
The National Agency for Dams and Water Transfer (ANBT) manages 75 dams in Algeria, dams with about 70% water reserve reaching 4.5 billion cubic meters thanks to heavy rainfall in recent years. Kinemetrics was chosen to provide an Earthquake Monitoring solution, connecting distributed IP-base Strong Motion Accelerograph (SMA) in real-time to the dam control rooms using Kinemetrics’ iDAM platform.
The system is designed to meet the objectives of Seismic Dam Monitoring and Alerting. The iDAM SMA stations are equipped with an Etna2 accelerograph and housed in a NEMA4 enclosure. Fibre optic cables connect the SMA to the dam control room. These connections assure fast data speeds and interference-free connection throughout the dam, up to the control room. Moreover, the Etna2 has built-in relays to report local alarms in case of acceleration threshold exceedance and/or State-of-Health (SOH) conditions. The system is designed to work 24/7 year after year.
The state-of-the-art Seismic Monitoring System was installed at the Barrage Oued That and the Barrage Soubella dams with WAN connection to the ANBT Data Centre in Algiers. There, a sophisticated processing tool calculates in real-time earthquake response spectra to generate alarms instantly in case of exceedance of operator-defined demand spectra.
MULTI SENSOR INTEGRATION
Instrumentation and software were integrated into a multi-sensor multi-location seismic network that produces high-quality real-time data.
SYSTEM FLEXIBILITY AND SCALABILITY
There are four monitoring points at each dam, the Crest, Foundation, Abutment, and the Free-Field. More stations and dams can easily be added to this iDAM implementation in future phases of the instrumentation project.
The engineering services include system design and integration, factory acceptance test, training, and installation support.
Etna2 accelerographs, synchronized with a timing accuracy of <1 microsecond, connected by fibre optic cables, assure more than 99% data return.
CuaDat Irrigation Dam is one of the largest irrigation dams in Vietnam.
The entire concrete surface inspection survey was conducted by the Department of Geophysical Application Research – Institute of Ecology and Works Protection.
Vucico Vietnam, a Representative for GSSI, assisted in the survey of the concrete dam which is part of the CuaDat Reservoir, the largest hydropower and irrigation construction in Vietnam with a capacity of 1.5 billion cubic meters. This reservoir, constructed between 2004 and 2009, is located upstream of the Chu River, Southwest of Hanoi and contributes to flood control ensuring a sufficient supply of water for more than 86,000 hectares of agricultural land, supplying water for domestic use and for industrial use. The dam measures 1,023m in length and 119m in maximum height.
The scope of this survey was to scan the entire surface of the dam, and the work was conducted over the course of several years. Some of the work could only be done when the water in the Reservoir dropped to levels that provided access to the surface of the dam usually covered by water.
The GSSI SIR® 30 system and 900 MHz antenna was used in the first stage of the survey to locate any areas with possible voids. Any voids identified would be repaired by injecting concrete through a drill hole. The challenge was not to damage or destroy the existing rebar in the structure. A StructureScan™ Mini XT was then deployed to refine the survey area that required repair by examining the rebar locations and marking an area where it was safe to drill.
The Kentucky Lock and Dam is located on the Tennessee River near Grand Rivers, Kentucky.
The 184-mile reservoir is the largest in the Eastern United States and spans across parts of Kentucky and Tennessee. Its existing navigation lock is 600ft (183m) long and the addition of a new landward navigation lock of 1,200ft (366m) increases the economic capabilities to commercially use the river for transport and commerce.
The United States Army Corps of Engineers has commissioned Robertson Geo customer Coastal Drilling as the geotechnical subcontractor tasked with acquiring borehole data of subsurface rock consistency and structure for the installation of rock anchors, and the investigation of foundation grouting along the existing lock chamber.
Coastal Drilling has deployed the High Resolution Optical Televiewer (Hi-OPTV) geophysical probe to map out subsurface features. The primary evaluation is the structural integrity for the bonding materials used for over one hundred high capacity rock anchors and a grout curtain to stabilize the rock of the existing lock, essential for the excavation phase for the new lock chamber.
Robertson Geo’s High Resolution Optical Televiewer probe was the preferred tool for investigation for its capability to collect 360 degrees of high resolution full colour borehole imagery, oriented to magnetic north. The Hi-OPTV collects real-time data that is viewable during the survey and can be presented and interpreted as a strip log if decisions are needed to be made on site using the data acquisition software – Robertson Geo-CAD®.
Geo-CAD® offers fracture analysis, rose diagrams, and steronets derived from the image in post processing. The user has the ability to populate sinusoids over selected features based on their dip and direction with the image and fractures oriented to magnetic north which aids when determining their dip angle or azimuth.
The deployment and evaluation of the site characterisation data from Robertson Geo’s Hi-OPTV is being used in a critical role for the geophysical evaluation for the planning and construction of the new 1,200ft (366m) lock addition at the Kentucky Dam.