Behaviour of anchored pile wall excavations in clays

A database of 35 case histories of anchored pile walls, collected mainly from Chicago, Boston, Texas and Washington, DC, USA as well as Taiwan, has been evaluated to predict the performance of deep excavations in clays. Various factors (including excavation depth, undrained shear strength, wall bending stiffness, factor of safety and pile embedment) affecting the deformation characteristics of excavations supported by anchored pile walls are presented and compared with findings of previous researchers. The normalised maximum wall displacement δH_max/H_e falls in the range of 0·1–0·7% and the location of δH_max is at a depth of 0·4H_e to 1·0H_e. Normalised maximum ground surface settlement δV_max/H_e is in a range of 0·1–0·4%. The ratio of maximum surface settlement to maximum lateral displacement falls in the range of 0·7–1·4, with an average value of 1·0. Maximum wall displacements are dependent on undrained shear strength and factor of safety and decrease with an increase in these factors. Maximum wall displacements decrease by increasing wall stiffness and most of the cases are bounded by values of EI/H_e between 35 MNm and 120 MNm. The effect of system stiffness is more pronounced in soft clays whereas deformations in stiff clays are less dependent on system stiffness.