Monotonic and cyclic lateral load tests on driven piles in chalk

This paper describes the results of a pile testing campaign on open-ended tubular steel instrumented piles driven into chalk. The testing campaign comprised the performance of both monotonic and one-way cyclic lateral load tests, performed at different times after pile installation. The tests were performed on five piles with uniform outer diameters of 762 mm and embedded lengths of 4 m and 10 m, in order to investigate the difference in response between short and long piles.
Lateral pile head load–displacement behaviour to failure has been analysed. The tangent stiffness evolution during monotonic loading has been evaluated at different times after pile installation and the chalk set-up has been found to have no effect on piles behaviour under lateral loading. The pile secant stiffness during cyclic lateral loading is also investigated. Accumulated pile head lateral displacements are discussed and their pattern is described by a logarithmic function that varies with number of cycles. The creation of a gap between the chalk and the pile during cyclic lateral loading was observed, which influenced the shape of the load-displacement loops. The influence of the instrument protection system was taken into account in analysing the results.