Refraction microtremors (REMI), method for determining shear wave velocities in the soil and GPR survey on the Barcelona Campus

Abstract

ReMi is the refraction microtremor technique. In contrast to other methods, it provides a simplified characterization of much larger volumes of the shallow subsurface in monodimensional profiles of vertical depth. ReMi is non-invasive and non-destructive technique, does not require any drilling, performed using surface wave (Rayleigh wave) generated by ambient noise, for example by human walk or transit of vehicles in urban areas. Combining seismic refraction method and ReMi, results can be collected by using the same geophone array configuration. The typical ReMi measured geologic material parameter, shear wave (s-wave) velocity, is a function of the module of the various material strata in the subsurface profile. Soil/rock contacts or contrasts between weaker and stronger geologic material horizons can be interpreted from ReMi data. Preliminary subsurface profiles can be developed from this information, and characterization of subsurface profiles between geotechnical borings, test pits and seismic refraction geophysical profiles can be accomplished. Second part of report deals with the practical lesson on the use of GPR equipment and devoted to the detection of buried utilities in an outdoor environment. The processing and interpretation of the collected GPR data through the commercial software REFLEXW is presented, as well.