Mechanical Behavior of Weathered Granite Exposed to Water

Abstract

Weathered granite has been widely used as an emerging foundation filler for constructing transportation infrastructure. However, various softened rocks weathered due to exposure to water have special properties. Thus, it is necessary to gain a thorough understanding of the various physical and mechanical properties of weathered granite after exposure to water in order to avoid engineering accidents. To this end, this paper conducted a series of undrained triaxial shear tests to compare the mechanical behavior of weathered granite in natural and saturated states. The results demonstrate that the strength of the weathered granite significantly declines when it is exposed to water, and it exhibits noticeable water softening characteristics. Consolidation methods also affect the mechanical properties of weathered granite. The degree of softening of weathered granite decreases with an increase in the deviator stress imposed by the deviator stress consolidation. Subsequently, we established an empirical model for the strain softening of weathered granite suitable for natural and saturated conditions. This model took the elastic modulus of weathered granite before the peak strength as a measure and introduced the strength parameters of the internal friction angle (φ) and the internal cohesion (c). First, the fitted function correlating c and φ with the plastic internal variable was determined, and then the relationship between the strength and the strain-softening parameters was established so as to obtain the complete stress–strain curve of the granite rock. Finally, validation studies were performed to address the capability of the model to predict permanent deformation. It provides a theoretical basis for predicting and calculating the strain softening of weathered granite exposed to water.

Keywords

• weathered granite
• mechanical behavior
• strain softening
• deviator stress consolidation
• empirical model