Dynamic analysis of GRP composite pipes under the coupled effects of traffic load and groundwater level fluctuations

Fluctuations in the groundwater level make the working conditions of GRP composite pipes below the groundwater level more complex than those of GRP composite pipes above the groundwater level. This paper describes the application of a three‐dimensional (۳‐D) refined finite element (FE) model to the analysis of a buried GRP composite pipe subjected to the coupled effects of traffic load and groundwater level fluctuations. First, the dynamic responses of the GRP composite pipes buried in dry soil were investigated with a full‐scale test and an FE model. The results show that the FE model predicted results similar to those observed in field pipes. Then, the dynamic responses based on the numerical results of pipes buried in dry soil under a traffic load and those of pipes buried in saturated soil under the coupled effects of a traffic load and groundwater level fluctuations were compared. Finally, a parametric analysis of the effects of the void ratio, permeability coefficient, and fluctuation period in the groundwater level in relation to the dynamic responses of the pipes was conducted. The results show that the mechanical behaviors of the pipes in dry soil were substantially different from those of pipes in saturated soil. Compared with pipes in dry soil under a traffic load, the stresses at the crown, springline, and invert of the bell under thecoupled effects of the traffic load and groundwater level fluctuations were lowered by ۴۴.۸%, ۵۲.۰%, and ۵۰.۳%, respectively, while those of the spigot were loweredby ۴۲.۰%, ۵۰.۳%, and ۴۹.۶%, respectively. The maximum principal stress and the vertical displacement were proportional to the void ratio and the permeability coefficient,while their relationship to the groundwater level fluctuation period was less straightforward.

Keywords:

GRP composite pipes , FE model , full‐scale test , groundwater level fluctuation , parametric analysis , traffic load