Effect of Freeze-Thaw Action on Porosity Change and Destruction of Weathered Bedrock in Different Lithology and Development of Destruction Model

Abstract

A freeze-thaw experiment was conducted to investigate the destruction mode of weathered bedrock in different lithologies. The experiment was conducted on bedrock samples of weathered granite (WGr), weathered granite porphyry (WGp), weathered shale (WS), weathered sandstone (WSa) and weathered rhyolite (WR). Because of freeze and thaw action, porosity of the bedrock samples increased and weight of the samples decreased. When porosity of WGr, WGp and WS increased greater than 0.43, 0.1 and 0.27, respectively, small pieces were detached from the main sample bodies. In contrast, freezing and thawing caused only slight increases in the porosity of WSa and WR and production of fine sediment from the surface. Depth of the sediment productions of WSa and WR due to one freeze-thaw cycle was equivalent to less than 1.0 and 0.2 mm, respectively. Hence, these rocks are exposed to only slight damage, which are at the ground surface. The experimental results were also used for developing a simple destruction model.