In situ ultrasonic method for estimating residual tension of wedge fix type anchors

Good maintenance of ground anchors installed along the slopes and the cuts of expressways is very important to keep those slopes and cuts stable and safe. In this research, nondestructive method which is a cheaper and quicker than extant method, to evaluate residual tension of ground anchors is introduced. Ultrasonic waves reflected back from the upper and lower surfaces of the bearing plate are recorded in the waveform and the maximum amplitudes of each of those reflected waves are compared. While comparing the average maximum amplitude of each reflected wave with corresponding tensile load, a good linear increasing trend is observed when 1st reflected wave from the lower surface of the bearing plate (WRL1). Comparison is made between all the representative average maximum amplitudes of WRL1 of both laboratory and field experiments with corresponding tensile stress (or tension). A generalized equation is then recommended which can be used for predicting residual tension of the anchors.