Page - 845 - in Book of Full Papers - Symposium Hydro Engineering

COMMISSION INTERNATIONALE DES GRANDS BARRAGES ------- VINGT-SIXIÈME CONGRÈS DES GRANDS BARRAGES Autriche, juillet 2018 ------- AN INTEGRATED GEOPHYSICAL INVESTIGATION FOR THE EARTHEN DAM INSPECTION: ELECTRICAL RESISTIVITY IMAGING, MULTICHANNEL ANALYSIS OF SURFACE WAVE AND GROUND PENETRATING RADAR Noppadol POOMVISES, Prateep PAKDEEROD, Anchalee KONGSUK Bureau of Engineering Topographical and Geotechnical Survey, ROYOL IRRIGATION DEPARTMENT, MINISTRY OF AGRICULTURAL AND COPERATIVES, (e-mail:npoomvises@gmail.com) THAILAND 1. ABSTRACT Royal Irrigation Department (RID) announces that an integrated geophysical investigation can provide useful information for the earthen dam inspection. Nondestructive geophysical techniques; Electrical Resistivity Imaging (ERI), Multichannel Analysis of Surface Wave (MASW), and Ground Penetrating Radar (GPR) have a great potential in identifying subsurface deficiencies and the results are intuitively acceptable. In relation to these activities, subsurface characteristics of particular interest must be inferred from the physical properties of clay core. Low or high resistivity range means relative moisture in embankment material and implies the homogeneousness of impervious clay core. The shear wave velocity measured by MASW can be numerically converted to undrained shear strength, implying the bearing capacity of compacted clay. The GPR image clearly reveals partial settlement of freeboard zone at the upper part of the old earthen dam as well as the area covered by filled material, if there was any treatment in the past. 845