Abstract
Large rockslides often exhibit long runout, suggesting a low mobilized shear resistance within their shear zone. Various weakening mechanisms are proposed to explain the hypermobility of rockslides.
To describe a specific event, a single mechanism is usually invoked, which is thought to dominate the entire runout. Herein, with reference to largely coherent landslides with a water-saturated shear zone, we explore how the combined action of particle crushing and thermal pressurization might cause hypermobility by promoting pore-water pressure buildup.
We develop a simple model based on mass and energy conservation for a block sliding on an inclined plane that we solve numerically. Parameter study is also applied to the model.
The results indicated that these two mechanisms could have comparable magnitude, and their synergy might promote longer runout. We suggest that particle crushing could control the initial rapid acceleration, but its contribution may gradually fade as an ultimate particle size distribution is attained and thermally induced pressurization may become dominant.
Particle crushing may lower the permeability and compressibility of the shear-zone material, enhancing the subsequent pressurization and runout.