Earth echo sounding technique for quality control of drilled shaft foundations

Abstract

Quality assurance of foundations, particularly deep-drilled shaft foundations, is becoming an important part of foundation construction in order to ascertain the applied load transfer to the surrounding soil/rock safely through a good foundation. Non-destructive testing techniques are widely used for the inspection and assessment of the integrity of drilled shaft foundations both before and after the concreting stage. The condition of drilled shafts is questionable when their depths become deeper. This leads to a high demand for a testing technique that can measure the construction of drilled shafts at an early stage before concreting them. This paper presents the application of the Ultrasonic Echo Sounding (UES) testing technique and describes the results of tests carried out on more than 90 drilled shafts from a range of contexts including the deep foundations of railways, hospitals and residential buildings in various Hong Kong construction sites.