A NEW DESIGN PROCEDURE FOR DRIVEN PILES AND ITS APPLICATION TO TWO JAPANESE CLAYS

抄録

The paper describes how research into the effective stresses developed on displacement piles has led to a new design procedure for driven piles in clay. The new approach calculates local shaft friction capacity from a failure criterion derived from (i) drained interface shear tests, combined with (ii) expressions which link the radial effective stresses at failure to the initial vertical effective stress (σ'_vo), the apparent overconsolidation ratio (or YSR), the clay's sensitivity (S_t) and the relative depth to the pile tip (h/R^*). Base resistance may be assessed by conventional methods, or estimated from a new relationship involving the local average CPT resistance, q_c. The new method is demonstrated and verified using data from two Japanese case histories involving tests on large instrumented driven pipe-piles.