Safety assessment of dams by analysis of the electrical properties of the embankment material

Variations in the electrical properties of embankment material were analyzed by laboratory experiments and field surveys to enhance electrical resistivity surveys frequently used for the safety assessment of dam embankments. The electrical responses were investigated through lab tests of core material and field surveys. The interpretation includes SPT correlation and the effect of grouting reinforcement. Kaolinite was used to examine variations in resistivity as a function of the degree of consolidation, due to the similar physical properties of kaolinite and the core material in embankments. The test showed that a drop in shear strength increases resistivity regardless of the water content. This result means that the porous zones of weak core material in an embankment may appear highly resistive in surveys. This observation implies that an electrical survey may fail to detect weak core material if only low resistivity zones are identified. The Standard Penetration Test (SPT) was performed to analyze the correlation between resistivity and ground stiffness. A mechanism to describe the variation in electrical resistivity due to grouting reinforcement is proposed and applied to actual field data.