Study On Analytical Solution Of Pile Composite Ground Under Flexible Foundation

The load transfer law and working performance of pile composite ground under flexible foundation with geotextile reinforced cushion were chosen as object of study. Considering influencing factors including a relative displacement on pile-soil interface, different settlement of soil in same depth, friction along the pile side varying with depth, and the reinforcement of geogrid, equilibrium equation of stress and compatibility equations of deformation in sysytem composed by flexible foundation-geotextile reinforced cushion-composite ground-substratum were established. Distribution pattern of stress and deformation in system, target which could manifest working performance of system directly such as pile-soil stress ratio and relative displacement on pile tip, were calculated by solving the equations. An engineering case indicated that the analytical method can well reflect the characters of pile composite ground under flexible foundation with geotextile reinforced cushion.Basic example was established based on the analytical method, then influence and interaction of factors on working performance of system were studied through single factor analysis and orthogonal analysis. There were 11 factors including height and compression modulus of fills, thickness and compression modulus of cushion, tensile strength of geogrid, pile replacement ratio, diameter and length of pile, compression modulus and ultimate friction of subsoil, compression modulus of underlying layer soil.Based on these studies, the influence of surface dry crust which is common in engineering projects was introduced. The analytical solution was got considering the existence of surface dry crust. Based on this analytical method, the basic example considering the influence of dry crust was established to discusse the impact of compression modulus, thickness and shearing strength parameters of dry crust on the work characters of the system.