Simplified Method for Analysing Pile-Supported Embankment Settlements over Soft Soil

A method for the settlement of pile-supported embankments over soft soil with due consideration of soil arching and pile-soil interactions is proposed. Traditionally, settlements comprising composite foundations and built under embankments are usually divided into two parts-reinforced and un-reinforced. However, when calculating the settlements, some assumptions which are somewhat disaccordance with the truth are made. In addition, some parameters employed in some traditional methods are uncertain and the nonuniformity of layered site is hardly to be considered. Therefore the access to a more accurate analytical results is restricted.Based on the arching model proposed by Hewlett and Randolph, a uniform coefficient has herein been incorporated to allow for evaluation of non-uniform vertical stresses acting on the soft ground. This, in turn, serves to deduce solutions for the arching effect in square and triangular pile configurations. In the method proposed, the load acting on the pile head and the resulting subsoil reaction could be evaluated through analysis of the soil-arching effect. The load at the pile tip can be calculated by employing the spherical cavity expansion theory. Subsequently, additional stresses induced by the load at the pile tip, subsoil reaction, and skin friction acting on the pile could be obtained through use of revised Mindlin's solution by considering the ground to be comprised of multi-layered soil. Settlement results, obtained by accounting for additional stresses, could then be calculated using the layer-wise summation method. Settlements of the pile head and ground surface could, thus, be evaluated by superimposing different partial settlements. The proposed method serves to analyse pile-head as well as ground-surface settlements and offers the advantage that the parameters employed in the analysis could be conveniently adopted and that the deduction procedure is concise. Comparison of results obtained using the proposed method with observed data and numerical results demonstrates that the proposed method is capable of accurately estimating the settlement of piles as well as ground surface of pile-supported embankments with only a slight deviation that varies from 5.0% to 14.4%, which is an acceptable value by engineering standards.