Experimental findings concerning the evolution of breach resulting from the seepage at earthen dams under different scenarios

Piping is one of the major phenomena which threaten earth-fill dam stability and safety. Piping depends on several geometric, hydraulic and geotechnical parameters and can cause erosion within the dam structure. This study involves time-dependent evolutions of the breach shape and flow rate from the breach corresponding to four different scenarios. Both homogeneous and clay cored earth-fill dams were constructed by using a sand-clay mixture consisting of 85% sand and 15% clay. The weak layer was created at bottom or at top of the dam bodies. The temporal evolution of the breaches was recorded using high-quality cameras installed at upstream, downstream and lateral sides of the flume. A magnetic flow meter placed on the discharge pipe measured the inflows. The flow rates from the breach were calculated by using the continuity equation describing the mass conservation. The so-obtained experimental findings are presented and interpreted. The primary objective of these experimental studies is to enable the calibration and validation of the numerical models employed in the corresponding computational analyses. This study revealed that in the laboratory conditions, it is also possible to monitor the evolution of breach geometries resulting from piping by using rock salt or by creating a weak non-compacted layer. As expected, the internal erosion began at downstream side and progressed toward upstream. Numerical analysis corresponding to the second scenario has been achieved and an acceptable compatibility between experimental and numerical results was found.