The Process and Mechanisms of Freezing and Thawing Deterioration of Petroglyphs under Snowmelt and Rainfall Infiltration

Abstract

Freeze–thaw cycles under the conditions of snowmelt and rainfall infiltration in winter are triggers for petroglyph weathering. Rock samples from the Helan Mountains were subjected freeze–thaw cycles under various conditions in laboratory testing, and the mass, elastic wave velocity and unconfined compressive strength were tested. The results show that the mass loss rate, wave velocity and compressive strength decreased. In addition, according to XRD analyses, the content of calcite and feldspar in the samples decreased, and according to SEM analyses, the microscopic pores grew. Considering the mass, mineral content and micro-voids, the variation decreases in the order: snowmelt group, rainfall infiltration group, normal freeze–thaw group. However, for wave velocity and compressive strength, the opposite results were observed. This research contributes to a better understanding of the weathering processes and mechanisms of petroglyphs in the Helan Mountains in winter.