Investigation of Disintegration Behaviors of Clay-Bearing Rocks by a New Methodology

Abstract

Disintegration behaviors of clay-bearing rocks are special engineering problems. Samples are isolated and unconstrained in previous disintegrating-durability tests, unlike clay-bearing rocks under the natural controlled condition in the field. Then, a methodology of disintegration testing regarding natural controlled conditions was evaluated to study the disintegration behaviors of clay-bearing rocks. The study results indicated that the fissure area ratio (F_AR) increases rapidly before the seventh wetting-drying cycle and then begins a stable trend. The fragment size distribution characteristics show that the proportion of small fragments gradually increases and that the proportion of large fragments gradually decreases with the increase in the number of wetting-drying cycles. Clay-bearing rock fragments larger than 2 mm disappear after seven wetting-drying cycles. The change characteristics of the disintegration resistance of the disintegrating clay-bearing rock are that, regardless of the critical fragment size diameter (D_cr) of complete disintegration, the slake durability index (I_(D)) and disintegration ratio (D_R) are reduced. The disintegration degree of aggregate fragments is further reflected by the D_R, which corresponds with the F_AR. A trend of the maximum shear stress related to the number of wetting-drying cycles has two stages: the first significant and then insignificant decrease. The critical number of wetting-drying cycles is seven, after which point the disintegrating clay-bearing rock fragments with a size coarser than 2 mm disappeared. The results indicate the highly positive correlation between strength and the D_R of the disintegrating clay-bearing rock.