Laboratory tests of unbound aggregate pavement base under cyclic loading and the impact of ground deformations caused by mining

an unbound aggregate base layer subjected to cyclic loading and the
impact of mining deformation. The article presents the
characteristics of the scale of changes in the stiffness of both the
pavement layers and the subgrade for a category III mining area,
i.e., for horizontal strains up to 6 mm/m. The characteristics are
based on previous experience, which takes into account the impact
of mining deformations that occurred in a category II mining area.
The aim of the article was achieved based on the results of
laboratory tests. These tests were conducted on a test stand that
enables the simulation of the cyclic loading of the surface of a
tested layer system and the horizontal strains of the ground. The
cyclic loading caused by the rigid plate simulated the movement of
vehicles. Numerical analysis of the issue for the conditions of
laboratory tests was also carried out. This analysis was aimed at
estimating the change in the parameters of individual layers in the
tested system in subsequent stages of the laboratory tests. The
results of the tests and analysis show that for horizontal tensile
strains of 0.0–6.0 mm/m, a reduction in the elasticity moduli to
approximately 35–45% for unbound aggregate and approximately
70% for fine-grained layers may occur.