Interface clogging between soil and attenuation layer of embankment based on LBM-DEM coupled numerical method

The reuse of excavated soil is a popular topic all around the world. To decrease the contaminants in excavated soil influencing the ground, an attenuation layer is generally used to absorb these contaminants and isolate the excavated soil and ground. The drainage clogging problem that is sometimes generated has attracted much attention in embankment engineering. The attenuation layer drainage effect is not only related to the loading capacity of the ground, but also to the soil properties. Thus, it is significant to clarify the mechanism of drainage clogging. As the micro monitoring of clogging is still difficult to achieve, a numerical simulation method is used in the present study to elaborate this mechanism. Based on the coupled lattice Boltzmann method (LBM) and discrete element method (DEM), the drainage clogging phenomenon during the filtering process is simulated from a micro perspective. The results indicate that particles can form an arch structure and lead to clogging above the pore of the attenuation layer. The formation of such a clogging arch structure prevents the discharge of soil particles and greatly decreases the fluid velocity, approximately 2.7 and 9.3 times for the two types of soil used in this study, namely, Soil A and Soil B, respectively. It is noted that the fluid velocity, rather than impermeability, remains a basic value. The velocity distribution around the pore of the attenuation layer has a certain shape depending on the velocity of the LBM cells. The size of this distribution regularly changes with the distance to the attenuation layer pore. In addition, knowledge of the soil skeleton is necessary for analyzing the arch-forming process in polydisperse particle systems. The larger particles (0.043–0.085 cm) are closely related to the formation of the soil skeleton, whereas the finer particles are related to the filling and stabilization of the soil skeleton. The clog stabilization of the soil particles in these two samples is mainly controlled by the average normal forces (1.87 × 10 −6 N and 1.20 × 10 −6 N, respectively) according to the variation in forces during the clogging process. Based on the analysis, an explanation of the clogging process is proposed in this study from a microscopic perspective, providing a better description of the soil skeleton clogging theory under embankment drainage.