Abstract: Taking the well vegetated slope soil in the Touzhai of Yunnan province as case study, a 3D macropores structure model is reconstructed based on the CT scanning and digital image processing technology. Then the soil skeleton is taken as the boundary of seepage field, and the bounce-back scheme is set to simulate the interaction between soil skeleton and water. The lattice Boltzmann method is applied to study the seepage behavior in the macropores of well vegetated slope soil. The results show that the preferential flow is formed in the channel with good longitudinal connectivity, and the flow velocity in the channel is larger than that of other regions. In the closed macropores or these with poor connectivity, the water conductivity is small and the flow velocity almost equals to zero. The flow velocity in the channel increases gradually from the wall of macropores to the center of the channel, and the relationship between flow velocity and distance to the center of channel is approximately quadratic parabola. Along the depth direction, the section with larger macropores porosity has the faster average seepage velocity of Uz. Overall, there is the similar trend for the section macropores porosity and the average seepage velocity, which indicates that the distribution of macropores in the well vegetated slope soil influences significantly on the seepage characteristics along the depth direction.

Key words: seepage field, macropores, well vegetated slope, reconstructed model, CT scanning technology, lattice Boltzmann method