Investigation on load sharing ratio of piles and soil in GRPS embankment with different pile types and geogrid layers under long-term cyclic loading

Abstract

Geosynthetic-reinforced pile-supported (GRPS) embankments are a primary method for mitigating subgrade settlement. However, the load transfer mechanism between piles and soil remains incompletely understood, with the load sharing ratio (LSR) between piles and soil serving as a critical indicator for this mechanism. This study conducted a model test at a similarity ratio of 1:10 to investigate the effects of load amplitude, load frequency, number of geogrid layers, and pile types on the LSRs of piles and soil in GRPS embankments. The test results show that the pile’s LSR increases with rising values of these parameters, while the corresponding LSR of the soil decreases. Among these parameters, the number of geogrid layers has the least effect on the LSRs of both piles and soil. Furthermore, the rigid long pile demonstrates a higher LSR than the flexible short pile, attributed to its greater stiffness. The influence of load frequency on the LSRs of the rigid long pile is also less significant compared to the flexible short pile. Variations of LSR increment can be predicted using a formula that incorporates the number of loading cycles. These findings provide deeper insights into the load transfer mechanism in the pile-soil system, contribute to the optimization of GRPS embankments design practice, and ultimately enhance performance and reliability of the GRPS embankments in geotechnical engineering applications.