A Preliminary Investigation on the Role of Brittle Fracture in the Kinematics of the 2014 San Leo Landslide

Abstract

The stability of high rock slopes is largely controlled by the location and orientation of geological features, such as faults, folds, joints, and bedding planes, which can induce structurally controlled slope instability. Under certain conditions, slope kinematics may vary with time, as propagation of existing fractures due to brittle failure may allow development of fully persistent release surfaces. In this paper, the progressive accumulation of brittle damage that occurred prior to and during the 2014 San Leo landslide (northern Italy) is investigated using a synthetic rock mass (SRM) approach. Mapping of brittle fractures, rock bridge failures, and major structures is undertaken using terrestrial laser scanning, photogrammetry, and high-resolution photography. Numerical analyses are conducted to investigate the role of intact rock fracturing on the evolution of kinematic freedom using the two-dimensional Finite-discrete element method (FDEM) code Elfen, and the three-dimensional lattice-spring scheme code Slope Model. Numerical analyses show that the gradual erosion of clay-rich material below the base of the plateau drives the brittle propagation of fractures within the rock mass, until a fully persistent, subvertical rupture surface form, causing toppling of fault-bounded rock columns. This study clearly highlights the potential role of intact rock fracturing on the slope kinematics, and the interaction between intact rock strength, structural geology, and slope morphology.provide kinematic release to blocks that were previously nonremovable [9]. The accumulation of brittle damage is a critical component in the development of footwall failures and large-scale, biplanar, and compound rockslides, due to the formation of a highly damaged transition zone at the interface between active and passive blocks [10][11][12]. Additionally, intact rock fracturing may cause the failure of nondaylighting rock wedges, due to the formation of a basal rupture surface caused by failure of rock bridges and coalescence of brittle cracks [13].The strength of intact rock is orders of magnitude higher than discontinuities; therefore, strength and size of intact rock bridges between discontinuities have a great impact on the stability of rock slopes [9]. A small amount (0.1-10%) of rock bridges favorably distributed within a rock slope strongly increases the stability of the slope [14,15]. Despite the major significance of intact rock bridges in controlling the behavior of rock masses, their characterization remains an extremely challenging task [14], and the deterministic quantification of the rock bridges existing along a rupture surface may be undertaken only after failure occurs [15][16][17]. Discrete fracture networks (DFNs) are consequently being increasingly employed in rock engineering to investigate the distribution and dimensions of rock bridges using a stochastic approach [18].In this paper, the effects of intact rock fracturing on the evolution of the kinematic freedom of rock slopes are investigated using the 2014 San...

Image‐based simulation of complex fracture networks by numerical manifold method

“…This reproduces the rear rupture surface observed in situ. 46 Also note that with the progressive undermining, the displacement in the y direction (Figure 18(B)) significantly increases, which increases the possibility of block falls. These above results validate the continuous and discontinuous simulation of complex fracture network by the NMM, and also are important references for the engineering designs.…”

“…For simplicity, the slope is simulated under the linear elastic assumption. Young's modulus and Poisson's ratio are chosen as San Marino Limestone forming this slope, 46 where E = 17 GPa, = 0.25. To get a clear discontinuous displacement field and to validate the proposed method, the tensile strength and the friction angles of the fractures are set as zero.…”

Mountain Landslides: Monitoring, Modeling, and Mitigation

“…Donati et al [9] study the progressive accumulation of brittle damage that occurred prior to and during failure, by using a synthetic rock mass approach. After the mapping of brittle fractures, rock bridge failures, and major structures using terrestrial laser scanning, photogrammetry, and high-resolution photography, numerical analyses are conducted using the 2D and 3D codes.…”

Kinematic Analysis of the 2020 Elliot Creek Landslide, British Columbia, Using Remote Sensing Data

“…High quality, massive rock masses, are more likely to produce structurally-controlled deformations and landslides, whereas low quality, highly fractured rock masses can promote the occurrence of soil-like landslides, such as roto-translational landslides and rock slumps (Hungr et al, 2014;Agliardi et al, 2018;Stead et al, 2021). The characteristics of the intact rock (e.g., compressive, tensile, and shear strength, deformation behavior, fracture toughness) can also control the behavior and stability of rock slopes constituted by massive rock masses, with a poorly interconnected discontinuity network, in which the detachment of landslides is subordinate to the brittle propagation of fractures and failure of intact rock bridges (Havaej et al, 2014;Donati et al, 2019).…”