Stereo particle image velocimetry measurement of 3D soil deformation around laterally loaded pile in sand

A developed stereo particle image velocimetry (stereo-PIV) system was proposed to measure three-dimensional (3D) soil deformation around a laterally loaded pile in sand. The stereo-PIV technique extended 2D measurement to 3D based on a binocular vision model, where two cameras with a well geometrical setting were utilized to image the same object simultaneously. This system utilized two open software packages and some simple programs in MATLAB, which can easily be adjusted to meet user needs at a low cost. The failure planes form an angle with the horizontal line, which are measured at 27°–29°, approximately three-fourths of the frictional angle of soil. The edge of the strain wedge formed in front of the pile is an arc, which is slightly different from the straight line reported in the literature. The active and passive influence zones are about twice and six times of the diameter of the pile, respectively. The test demonstrates the good performance and feasibility of this stereo-PIV system for more advanced geotechnical testing.