Influence of uncertainties: A focus on block volume and shape assessment for rockfall analysis

Umili, Gessica; Taboni, Battista; Ferrero, Anna María

doi:10.1016/j.jrmge.2023.03.016

Cited by 9 publications

(13 citation statements)

References 33 publications

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“…Block size can be quantified through the use of different approaches, both deterministic and probabilistic. In this study, we follow the approach to block size description proposed by Lu & Latham (1999) [20], expanded in later works such as the one presented in Umili et al (2023) [18]. In these works, the approach to the quantification of block size relies on probability distributions describing the spacing of the discontinuity sets identified in the rock mass: on their basis, the block volume distribution can be computed, employing the well-established Palmstrom's formula [37]; this equation, which considers the block generated by the intersection of three discontinuity planes, is not geometrically proven and, actually, it tends to either underestimate or overestimate the block size, depending on the reciprocal orientation of the sets involved.…”

Section: Block Volume Block Shape and Source Area Identificationmentioning

confidence: 99%

“…In these works, the approach to the quantification of block size relies on probability distributions describing the spacing of the discontinuity sets identified in the rock mass: on their basis, the block volume distribution can be computed, employing the well-established Palmstrom's formula [37]; this equation, which considers the block generated by the intersection of three discontinuity planes, is not geometrically proven and, actually, it tends to either underestimate or overestimate the block size, depending on the reciprocal orientation of the sets involved. A solution to this problem was recently found, and a new formulation was introduced [18]. Although apparently more complex than the one previously mentioned, this equation is geometrically proven and correctly estimates the block size.…”

Section: Block Volume Block Shape and Source Area Identificationmentioning

confidence: 99%

“…Although apparently more complex than the one previously mentioned, this equation is geometrically proven and correctly estimates the block size. Applying the methodology described by Umili et al (2023) [18], the IBSD can then be quantified. Both Palmstrom's formula [38] and the new equation can be described as follows:…”

Section: Block Volume Block Shape and Source Area Identificationmentioning

confidence: 99%

“…UAV-based techniques provide a cheap and high-resolution solution for the definition of the morphological parameters describing a slope [14] but also give important information required to define the numerical models, both 2D and 3D, commonly employed to quantify and then map the hazard produced by phenomena such as rockfall and then develop a proper mitigation approach [15][16][17]. In this regard, it is worth mentioning the fact that non-contact techniques for rock mass surveys have proven even more useful due to the high quantity of quality data they can provide, allowing for proper statistical treatment [18] and the use of probabilistic approaches. Among others, one with significant potential involves the definition of an In Situ Block Size Distribution (IBSD) [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…A similar approach should also be employed when dealing with block shape. It is proven that the shape of a falling block significantly influences its possible trajectories and energies [18,23] or the interaction between the block itself and the vegetation it may encounter along its path downslope [24]. The literature is also rich in examples of methods for classifying block shapes [25,26] and tools and software that model rockfall dynamics accounting for block shape [27][28][29].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A Design Scenario Approach for Choosing Protection Works against Rockfall Phenomena

Taboni,

Umili,

Ferrero

2023

Remote Sensing

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Proximity remote sensing techniques, both land- and drone-based, allow for a significant improvement of the quality and quantity of raw data employed in the analysis of rockfall phenomena. In particular, the large amount of data these techniques can provide allows for the use of probabilistic approaches to rock mass characterization, with particular reference to block volume and shape definition. These, in return, are key parameters required for a proper rockfall hazard assessment and the optimization of countermeasures design. This study aims at providing a sort of guide, starting from the data gathering phase to the processing, up to the implementation of the outputs in a probabilistic-based scenario, which is able to associate a probability of not being exceeded with total kinetic energy values. By doing so, we were able to introduce a new approach for the choice of design parameters and the evaluation of the effectiveness of mitigation techniques. For this purpose, a suitable case study located in Varaita Valley (Cuneo, Italy) has been selected. The area has been surveyed, and a model of the slope and a digital model of the rock faces have been defined. The results show that a 6.5 m3 block has a probability of not being exceeded of 75%; subsequent simulations show that the level of kinetic energy involved in such a rockfall is extremely high. Some mitigation techniques are discussed.

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Section: Block Volume Block Shape and Source Area Identificationmentioning

confidence: 99%

Section: Block Volume Block Shape and Source Area Identificationmentioning

confidence: 99%

Section: Block Volume Block Shape and Source Area Identificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A Design Scenario Approach for Choosing Protection Works against Rockfall Phenomena

Taboni,

Umili,

Ferrero

2023

Remote Sensing

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Modeling Ellipsoidal Block Impacts by an Advanced Rheological Model

2023

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In this paper, an advanced rheological model for impacts of ellipsoidal blocks on deformable ground surfaces, introducing the effects of block eccentricity and orientation at impact, is presented. This allows us to assess impact penetration and force, restitution coefficients, and block trajectories. A parametric analysis was carried out by considering different block aspect ratios, impact angles and initial block orientations at impact. The results are presented in terms of restitution coefficients, penetration and force time histories, maximum penetration depth, maximum force and rotational/total kinetic ratios. Impacts along the major block axis, versus those along minor axis, are characterized by larger penetrations (ranging from 3.3 to 50%), shorter impact durations (ca 50%) and very slightly larger vertical forces (ranging from 0.3 to 60%) according to the model parameter used. In contrast, the impact angle is shown to strongly affect maximum penetration and force values, and markedly increase rotation at impact. Analogously, normal restitution coefficient is severely dependent on impact angle, with a variation of more than two orders of magnitude. A mathematical expression for computing the energetic restitution coefficient from the normal and tangential apparent restitution coefficients and the ratio between the rotation and total kinetic energy is proposed. This overcomes the drawback of classical restitution coefficients greater than one when a change in block rotation occurs allowing us to bracket the coefficient of restitutions values to support and improve classical rock fall simulations also highlighting their intrinsic limitations. Finally, the effects of block geometry and initial angular velocity on rockfall simulations were analyzed by implementing the approach in the HyStone simulation code. The simulated frequencies of the maximum height during each ballistic trajectory follow an exponential distribution, whereas those for normal and tangential apparent restitution coefficients follow normal distributions.

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A New Analytical Solution for Calculating Rock Block Volume

Umili,

Carriero,

Taboni

et al. 2024

Rock Mech Rock Eng

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The study of rock slope stability and evolution suffers from many uncertainty factors related to block size and shape, and slope morphology. While nothing can be done to remove the aleatory component of these uncertainties, efforts in reducing the epistemic ones are desirable. This research aims to propose a new analytical solution for calculating rock block volume in the case of three discontinuity sets whose orientation and true spacing are known. Researchers and practitioners can take advantage of such a correct analytical formula thanks to its easiness of use: guidelines based on stereogram are provided in order to explain how to obtain the required input data. The correctness of the equation is demonstrated by comparing the results of the new solution applied to 12 theoretical blocks with those obtained with 3DEC (Itasca Consulting Group). Also, the differences with respect to results obtained with the well-known Palmstrøm’s formula are reported. The new methodology is applied to the case study of Elva valley road (Northern Italy), which is overhung by steep rocky cliffs and is subject to the consequences of frequent rockfall phenomena. The results are used to discuss the proposed method’s applicability: while it is evident that such a formula is not able to compete with the great potentiality of DFNs, this user-friendly tool can quickly and at no cost assess rock block volume in rockfall or rock slope stability studies.

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Influence of uncertainties: A focus on block volume and shape assessment for rockfall analysis

Cited by 9 publications

References 33 publications

A Design Scenario Approach for Choosing Protection Works against Rockfall Phenomena

A Design Scenario Approach for Choosing Protection Works against Rockfall Phenomena

Modeling Ellipsoidal Block Impacts by an Advanced Rheological Model

A New Analytical Solution for Calculating Rock Block Volume

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