  We study dry, dense active nematics at both particle and continuous levels.
Specifically, extending the Boltzmann-Ginzburg-Landau approach, we derive
well-behaved hydrodynamic equations from a Vicsek-style model with nematic
alignment and pairwise repulsion. An extensive study of the phase diagram shows
qualitative agreement between the two levels of description. We find in
particular that the dynamics of topological defects strongly depends on
parameters and can lead to ``arch'' solutions forming a globally polar, smectic
arrangement of N\'eel walls. We show how these configurations are at the origin
of the defect ordered states reported previously. This work offers a detailed
understanding of the theoretical description of dense active nematics directly
rooted in their microscopic dynamics.
