Application of Surface Waves for the Geotechnical Characterisation of Dykes

Recent flood events in central Europe accompanied by the failure of river dykes have shown a clear need in effective and reliable methods to survey and monitor the structure of earth-fill dams. Among the geophysical techniques the imaging of the electrical resistivity is used in most cases, occasionally ground penetrating radar is applied in the frame of the search for subsurface facilities, seismic methods are rarely used. This paper focuses on the multichannel analysis of surface waves method (MASW) to determine elastic soil properties and aims to extend its application field to dyke and dam structures. An elaborated testing campaign was conducted and provided the chance to collect experiences in the practical use. Test results obtained at one test site are selected and presented in comparison with the conclusions from borehole logs. A remarkable relation between the shear wave velocity and the consistency of the clay liner was found. Valuable additional information on the composition of dyke body and base could be obtained. Possible influences of the dyke's topography on the test results were studied by means of a numerical analysis which showed the principal applicability of standard processing procedures.