Estimating the flaw size in drilled shafts using an impulse response method

Abstract

Flaws could occur in drilled shafts due to improper quality control, poor workmanship, and unexpected construction mistakes, and thus seriously decrease the loading capacity. This paper proposes a flaw size estimation formula for use in the impulse response test of drilled shafts. Numerical models were built to develop the estimation formula. The experimental cases also validate the estimation. The flaw depth ratio and stiffness ratio are two key parameters to accomplish the estimation. With the evaluation results of the formula, one can know the possible minimum flaw size in the drilled shaft and further remedial measures can be taken immediately. Furthermore, the detectable shaft slenderness ratio is shown to vary from 10 to 30, depending on the stiffness ratio.

A Study on Integrity Testing for Platform-Pile Systems considering Wave Propagation

“…e impulse-response test can be used to estimate the aw size of damaged pile structures [2]. e low-strain integrity test (LST) is an NDT method for assessing the structural integrity of piles in soil.…”

Integrity Testing of a Platform‐Pile System Using a Sensor Array and Wavenumber Domain Analysis

“…Low-strain integrity testing (LST) has been utilized to assess the structural health of piles in soil for decades. e piles are subjected to an impact force at the pile head in an impulse response test, and the re ected wave signals are analyzed to evaluate the damage [10,11]. In the traditional LST method, the optimal distance between the striking point and the receiver is 0.5R-0.7 R when the impact location is on the top surface of the pile [12][13][14].…”