Defect Identification, Remediation, and Performance Monitoring of a Drilled-shaft Foundation; a Case Study

摘要

Crosshole sonic logging (CSL), a nondestructive test method to investigate the integrity of cast-in-place concrete structures, identified defects within one of six, 4-ft diameter, 50-ft deep, drilled-shaft foundations for an emergency-reserve water (ERW) tank in Clark County, NV. Additional nondestructive testing and a coring program confirmed the presence of noncemented materials at depths where CSL identified velocity anomalies within the foundation. After clearly identifying the defective area, a remediation program that included pressure grouting and instrumentation to monitor the in-situ behavior of two of the foundations was performed. The ERW tank case study illustrates the accuracy of CSL for identifying depth and location of defects in concrete support foundations, while the postremediation data for the foundation provides information on the long-term behavior of a remediated foundation.