Change in Horizontal Stress in Soil from Changing Shear Wave Velocity - A Laboratory Investigation

We performed a new experiment on an unconsolidated sand sample in a biaxial pressure chamber to observe the effect of horizontal stress on seismic shear-wave velocity. Multi-offset seismic reception was successfully implemented in the laboratory scale. From changes in shear-wave moveout velocity observed in a receiver array we could distinguish the effect of horizontal stress change. The approach appears to be realisable in field with multi-receiver seismic CPT. This should lead to a new methodology for in-situ monitoring of horizontal stress change in soil. Further, we found a good match between the observed and the modelled shear-wave velocity change as a function of horizontal stress. This observation reinforces the possibility of implementing the model-based integration of seismic and CPT data, proposed earlier, for obtaining unique estimates of in-situ porosity and horizontal stress.