Combination of Near Surface Geophysical and Geotechnical Methods for Exploring Construction Sites

The application of seismic, DC geoelectric and GPR technique in combination with CPT-surveys has been tested in order to describe the subsurface structures of construction sites for traffic and transportation systems more effectively and reliable. First field tests are carried out at a test site. 15 CPT surveys were done along a profile of 700 m length. The results show that the field is characterized by a channel structure of different sediment and a changing stiffness of material in the deeper underground. Afterwards a seismic survey was done with a land-streamer (4.5 Hz geophones). The data were generated into shear wave velocity (Vs) profiles by MASW (Multi Channel Analysis of Surface Waves). The analysis of shear waves display the layering in the shallow underground and the changing of stiffness in the deeper ground. The DC geoelectric and GPR are more sensitive for the anomaly caused by the channel. The results show that the applied geophysical methods are suitable to display geotechnical relevant structures at our test side. In future, geophysical investigations will be evaluated as a prerequisite for reliable and less expensive geotechnical surveys. Furthermore, the derivation of geotechnical parameters from geophysical investigation will be tested.