Behaviors of pile-supported embankments in highway engineering

摘要

Based on the variational approach for pile groups embedded in soil modeled using a load-transfer curve method,a practical method was conducted to estimate the settlement of symmetric pile group supported embankments.The working mechanism of composite foundations improved by rigid or semi-rigid columns is analyzed by this method.Under equivalent strain conditions,the pile-soil stress ratio approaches the pile-soil modulus ratio up to a limited value of pile stiffness (R_m < 10);in the subsequent stages of high pile stiffness (R_m > 10),a further increase in the pile-soil modulus ratio cannot lead to a significant increase of stress transferred to the columns in composite foundations.The major influencing factor of the stress concentration from soil to pile in a high pile-soil modulus ratio is the padding stiffness.For the composite foundation improved by cement mixing columns,the effective column length is about 15 to 20 m and it is a more economical and effective design when the column length is less than 15 m.