This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods. The first configuration involved conducting artificial weathering on limestone using the freezing and thawing (F-T) for 40 cycles. The mechanical parameters of the samples were measured at the end of the 40th cycle. In the second configuration, a series of specimens underwent salt crystallization (S-C) tests for 20 cycles. Experimental results were validated using discrete element method (DEM). Next, the weathered limestone model with dimensions of 108 mm × 54 mm were prepared. The weathering layers were tested at four different thicknesses (i.e. 2.5 mm, 5 mm, 7.5 mm, and 10 mm) and three different positions (at the surface, 5 mm under the rock surface, and 10 mm under the rock surface). According to the results, weathering depth and thickness have a considerable effect on the failure process. The results also showed a correlation between the values of compressive strength and failure mechanisms associated with the weathering layer. The numerical results revealed that the tension crack was the dominant factor. Additionally, with increasing weathering thickness, Young's modulus, crack initiation stress, and final strength decreased in constant weathering depth. The results also demonstrated that the failure progress of the numerical models was similar to that observed in the laboratory.

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Keywords: Limestone, Weathering depth, Weathering thickness, Failure pattern, Particle flow code in two dimensions (PFC2D)