Pore Pressure Measurement in Blast-Induced Liquefaction Experiments (05-1019)**
Kyle M. Rollins, Brigham Young University
J. Dusty Lane, Lane Engineering, LLC
Emily Dibb, Brigham Young University
Scott A. Ashford, Oregon State University
A. Gray Mullins, University of South Florida

Blast-induced liquefaction experiments have been conducted at a number of test sites to evaluate lateral foundation resistance and soil improvement techniques. Tests can be constructed at full-scale without waiting for an earthquake to occur. In this extreme environment, pore pressure transducers must survive transient blast pressures of 41.4 MPa (6000 psi), yet have enough resolution to measure residual pore pressures of ± 0.69 kPa (0.1 psi). Three different transducer types were evaluated under these demanding conditions and the piezoresistive transducer was clearly found to be the most robust. These sensors were repeatedly subjected to extreme blast pressures and vibration, but still were able to provide accurate time histories of residual pore pressure despite occasional baseline shifts. Although these piezometers are more expensive than the other types, installation techniques were developed which allowed the piezometers to be recovered and reused in subsequent tests to reduce overall costs. These pore pressure sensors make it possible to define the extent of the liquefied zone during blast liquefaction experiment and to understand the soil behavior during cyclic loading of deep foundations.