Full-Scale Laboratory Tests Using a Shape-Acceleration Array System

Geotechnical instrumentation using Micro-Electro-Mechanical Systems (MEMS) are relative newcomers to this field and, as such, require extensive validation testing. This paper presents the use of a Shape-Acceleration Array (SAA) to instrument full-scale laminar container tests at the University of Buffalo. The SAA is a sensor array based on MEMS accelerometer measurements of angles relative to gravity. The sensors are contained in 30 cm long rigid segments which are connected by composite joints that prevent torsion but allow flexibility in two degrees of freedom. These rigid segments and flexible joints are combined to form a sensor array which is capable of measuring three-dimensional (3D) ground deformations at 30 cm intervals and 3D accelerations at 2.4 m intervals to a depth of 100 m. Two of these MEMS-based sensor arrays were utilized in a series of tests as part of a liquefaction and lateral spreading study. Extensive instrumentation was possible in this laboratory setting, thus the acceleration and deformation measurements from the SAAs can be compared to the traditional instrumentation, such as accelerometers and potentiometers. The goal of validating and calibrating the measured accelerations and displacements of the SAA system was achieved through these full-scale tests.