Identification of zones of increased permeability using numerical modelling of temperature distribution - an ISMOP case study

Abstract

The physical condition of earthen levees changes over time. Levee weakening can be caused by the leaching of fine grains of soil or by animal activity. Weakened areas can potentially cause destabilization or even collapse. Assessment of the physical condition of levees using GPR and geodetic measurements does not always correctly detect areas of increased permeability. Thermal anomalies, caused by existing zones of high permeability, are observed in levees during the transition of flood waves. They are generated by rapid infiltration of water with a different temperature than the temperature inside the levee. Therefore, inner thermal measurements may be used to detect places with higher permeability. This research was realized with 2D numerical modelling. Main aim was test possibility of using temperature sensors in weak zone detection. Test with different theoretical permeabilities proved that it is possible only in specific condition (i.e. thermal contrast). The geometry and geomechanical properties of the studied levee were taken from the ISMOP project (polish acronym: Computer system for monitoring river embankments).