New approach in the application of seismic methods for assessing surface excavatability of sedimentary rocks

In the present study, a new approach on the application of seismic methods for assessing the excavatability of sedimentary rocks for surface excavations is proposed. The excavatability classification system has been developed based on seismic S-waves velocities determined by the multichannel analysis of surface waves. Prior to practical excavations carried out with different excavation methods (blasting, hydraulic breaking, ripping and digging), extensive field and laboratory studies were performed on eight sedimentary rock sites displaying a wide range of weathering and strength conditions in the area of Croatian karst (Dalmatia, Istria, Gorski Kotar). The investigation involved parameters of intact rock, such as compressive strength and point load strength, and parameters of rock mass such as seismic P-waves and S-waves velocities, geological strength index, discontinuity spacing and rock quality designation from borehole core. A new classification was proposed by comparing the measured V_S and applied excavation methods on the studied sites. Estimates of several existing classifications were used for comparison and verification. It was found that the estimates of the proposed model are comparable with the estimates of previous research. The proposed method is not applicable to igneous and metamorphic rocks, or for subsurface excavatability assessments.