2.3.3. Instrumentation
Since centrifuge scaling laws apply to the model in its entirety with the inclusion of any relevant instrumentation, miniaturised transducers and cables were used in limited numbers to minimise their influence on the structural response and avoid reinforcement of the soil. In line with this and to overcome saturated transducer responses, small 120 g micro-electromechanical system (MEMS) accelerometers were installed on the structure and damper instead of bulkier piezo-electric accelerometers. Arrays of piezoelectric accelerometers were positioned in the soil underneath the structure and in the free-field. A linear variable differential
transformer (LVDT) was positioned in the free-field to measure soil settlement throughout testing. The LVDT was founded on the sand surface by means of a circular pad footing to ensure a reliable measurement of soil settlement. An air hammer was installed at depth in the soil to generate shear waves. The propagation of these waves through the soil was picked up by a vertical array of piezoelectric accelerometers positioned directly above the air hammer
in order to measure the shear wave velocity (vs) and obtain an estimate for the soil stiffness.