Instrumented Becker Penetration Testing Using Wireless Data Transmission

摘要

Becker penetration tests have long been used to evaluate the liquefaction susceptibility of gravelly deposits. Historically, only the energy measured at the head of the Becker drill string was used in this assessment. In recently described instrumented Becker penetration tests (iBPT), the energy transfer to both the head and the toe of the closed-end Becker drill string has been used to calculate a continuous, normalized blow count versus depth. This continuous blow count profile is used to identify liquefaction susceptible layers. The strain and acceleration measurements acquired at the head and toe locations in the iBPT are typically obtained using cabled connections. One drawback to widespread iBPT usage has been the limited number of available systems as well as the cable connection to the toe sensor location, which must be internally threaded through each rod section as it was added to the drill string. This paper describes three cases where iBPT data was acquired using readily available dynamic foundation testing equipment. Acquiring and processing strain and acceleration measurements from the drill string head and toe using conventional dynamic testing equipment increases the routine availability of the iBPT methodology and encourages its widespread use in the liquefaction assessment of gravelly deposits.