Predicting blast-induced liquefaction within the New Madrid Seismic Zone

Abstract

The Turrell Arkansas Testing Site (TATS) is located in Northeastern Arkansas, United States. The site consists of approximately six meters of overconsolidated clay underlain by loose liquefiable sand deposits. Numerous traditional (rotary-wash boring with sample collection) and advanced (seismic piezocone soundings) geotechnical investigations have been performed at this site. A controlled-blasting testing program was also performed at the TATS to determine the blasting layout (the appropriate amount of explosive charges, the detonation delays, and the charge spacing), and to verify induced liquefaction of the soil deposit at a testing site located within the New Madrid Seismic Zone (NMSZ). The results obtained from the installed transducers and the pre- and postblast cone penetration tests (CPT) are discussed. Although, the CPT were performed when the excess porewater pressures were dissipated, a review of CPT profiles after blasting showed no evidence of increase of cone tip resistance and sleeve friction. Due to the small amount of explosive charge weight that was used, the excess porewater pressure ratio values only increased above the unity at the depth of 11.30 m. A review of the existing empirical models used to predict blast-induced porewater pressure responses and liquefaction is presented. A new empirical model that accounts for the in-situ soil properties, to estimate the excess pore pressure ratio, was developed and is presented herein.