Civil Engineering applications
Rippability measures the degree of difficulty to excavate any given soil or rock. It is a significant aspect of the preliminary work of any civil engineering project.
The rippability of rock depends on the geology and physical characteristics of rock materials. An accurate evaluation of rock rippability will improve the prediction of the excavation effort, the construction schedule, cost estimations, facilitate the selection of proper extraction equipment and maximize overall production.
Rippability assessment is usually performed with the determination of P-wave seismic velocities. Thus, seismic refraction is the most commonly used geophysical method. Seismic refraction surveys are conducted to measure the seismic compression velocity (P-wave) and estimate the subsurface stratigraphy. It is important to point out that seismic velocity is influenced by many factors, such as the presence of moisture and rock fractures.
Measured seismic velocity models are transformed into rippability charts as those published by Caterpillar Inc. In these charts, P-wave seismic velocity is converted into a rippability degree according to a given ripper model. The estimated rippability degrees derived in this way do not consider other important factors, such as rock hardness, weathering, joint spacing and continuity, and strike and dip of the bedrock. These other parameters can be studied, for instance, with a GPR study or an ERT proflle.