Model Test on Lateral Loading Performance of Secant Pile Walls

The mechanical behaviors of secant pile walls under lateral loading are complex with regard to their irregular cross sections and bonding quality of secant faces. A comprehensive model test was designed and conducted to investigate the stress states and failure modes of secant faces, the bearing capacities, and the flexural rigidity of secant pile walls under various lateral loading conditions. The model test consisted of three types of tests (shear, tension, and bending). All the tests accounted for the most sensitive factor affecting the bonding quality of secant faces [i.e., time interval of bonding (TIB)]. The commonly used secant pile wall of plain-reinforced-plain (PRP) type, with RC piles and plain concrete piles (PCPs) arranged alternatively, was chosen for the model test. Based on the interpretation of the test data, the primary findings were obtained as follows: (1) the failure modes of secant pile walls were governed by the bonding quality of secant faces, which depended on TIB; (2) the shear capacities of secant pile walls should be determined in accordance with the failure modes of secant faces; (3) secant faces in tension were more prone to damage than in shear and thus should be avoided in the design of secant pile walls; (4) the contribution of PCPs to the overall bending capacity of the secant pile walls was significant and should be considered in design to fully mobilize the potential bearing capacity of secant pile walls; and (5) stable rigidity of secant pile walls was achieved at the sum of individual rigidities of secant piles in the bending test, thus showing the contribution of PCPs to the rigidity of secant pile walls.