Material Spatial Variability and Slope Stability for Weak Rock Masses

Hsu, Sung‐Chi; Nelson, Priscilla P.

doi:10.1061/(asce)1090-0241(2006)132:2(183)

Cited by 52 publications

(10 citation statements)

References 10 publications

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“…It is well known that compressive strength decreases as saturation increases; however, there are only a handful of published studies that address this issue and even fewer studies on mechanics of partially saturated mudstone (Hawkins & McConnell, ; Dewhurst & Siggins, ; Hsu & Nelson, ; Romana & Vasarhelyi, ; Dewhurst et al, ; Sarout et al, ; Dewhurst et al, ; Zhou et al, ). Fundamentally, the lack of studies completed on partially saturated mudstone samples has resulted in an estimation of mechanical parameters not entirely representative of the subsurface environment, which is at least partially saturated with water, oil, gas, or some combination of these fluids.…”

Section: Discussionmentioning

confidence: 99%

Effects of Anisotropy and Saturation on Geomechanical Behavior of Mudstone

2019

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The abundance of mudstone in Earth's crust and its academic and industry applications has led to advancements in the understanding of mudstone deposition and preservation. However, there are few quantitative geomechanical studies on mudstone. To test correlations between anisotropy, fluid saturation levels, and deformability and strength parameters in mudstone, a suite of indirect tensile and unconfined and triaxial compression tests was completed on samples from the Mancos Shale and the Agrio Formation. Discs or plugs were tested with axial loading parallel or perpendicular to bedding, at various confining pressures, and at saturation levels from 0 to 17%. Tensile strength, compressive strength, Young's Modulus, Secant Modulus, stress drop, and energy released exhibit mechanical anisotropy and decrease due to saturation. Tensile strength anisotropy revealed the weakness of heterolithic bedding in mudstone, as tensile fractures commonly propagated along bedding interfaces. Saturation increased mechanical anisotropy for tensile and compressive strength. A compressive strength reduction of 39% to 75% was observed between dry and partially saturated plugs. Lithofacies were used to classify lithologic variations in different types of mudstone. When partially saturated, sandstone‐bearing facies revealed a greater reduction in strength and moduli than clay‐rich mudstone facies. Empirical relationships between partially saturated and dry sample strength and moduli are proposed, to allow for estimation of deformation and failure behavior under in‐situ conditions. The effects that saturation, orientation, and lithofacies have on mechanical behavior are of interest in numerous engineering and academic applications, including fault behavior, induced fracturing of hydrocarbon and geothermal reservoirs, and nuclear waste disposal.

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Section: Discussionmentioning

confidence: 99%

Effects of Anisotropy and Saturation on Geomechanical Behavior of Mudstone

2019

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“…The application of probabilistic methods in rock mass geomechanical characterization have been studied in many researches at different domains of geotechnical engineering such as rock slope stability e.g. [16][17][18][19] and underground rock mechanics such as tunnel stability [20][21][22][23], stope stability [24][25][26] and pillar stability [27][28][29]. However, few studies used probabilistic approaches to quantify the impact of lithological heterogeneity identified by geological surveys and laboratory tests on the uncertainties of the rock mass geomechanical characterization.…”

Section: Introductionmentioning

confidence: 99%

Geomechanical characterization of a heterogenous rock mass using geological and laboratory test results: a case study of the Niobec Mine, Quebec (Canada)

et al. 2021

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To conduct a successful geomechanical characterization of rock masses, an appropriate interpretation of lithological heterogeneity should be attained by considering both the geological and geomechanical data. In order to clarify the reliability and applicability of geological surveys for rock mechanics purposes, a geomechanical characterization study is conducted on the heterogeneous rock mass of Niobec Mine (Quebec, Canada), by considering the characteristics of its various identified lithological units. The results of previous field and laboratory test campaigns were used to quantify the variability associated to intact rock geomechanical parameters for the different present lithological units. The interpretation of geomechanical similarities between the lithological units resulted in determination of three main rock units (carbonatite, syenite, and carbonatite-syenite units). Geomechanical parameters of these rock units and their associated variabilities are utilized for stochastic estimation of geomechanical parameters of the heterogeneous rock mass using the Monte Carlo Simulation method. A comparison is also made between the results of probabilistic and deterministic analyses to highlight the presence of intrinsic variability associated with the heterogeneous rock mass properties. The results indicated that, for the case of Niobec Mine, the carbonatite-syenite rock unit could be considered as a valid representative of the entire rock mass geology since it offers an appropriate geomechanical approximation of all the present lithological units at the mine site, in terms of both the magnitude and dispersion of the strength and deformability parameters. Article Highlights Evaluating the reliability and applicability of geological survey outcomes for rock mechanics purposes. A geomechanical characterization study is conducted on the heterogeneous rock mass by considering the various identified rock lithotypes. The geomechanical parameters of intact units and their associated variabilities are used to stochastically estimate the geomechanical parameters of the heterogeneous rock mass by employing the Monte Carlo Simulation. A comparison is also made between the results of probabilistic and deterministic geomechanical analyses. The results indicate that, in the case of Niobec Mine, the combined syenite-carbonatite rock unit could be considered as a valid representative of the entire rock mass.

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“…Lumb, 1966;Soulié et al, 1990;Kim, 2002;Elkateb et al, 2003;El Gonnouni et al, 2005;El-Ramly et al, 2005;Hicks & Onisiphorou, 2005;Wang & Chiasson, 2006;Jung et al, 2008;Akbas & Kulhawy, 2010;Suchomel & Mašín, 2011;Zhao et al, 2013), treated formally using random-field methods (e.g. Vanmarcke, 1983;Nübel & Karcher, 1998;Griffiths & Fenton, 2004;Niemunis et al, 2005;Hsu & Nelson, 2006;Andrade et al, 2008;Kim & Santamarina, 2008;Cho & Park, 2010;Suchomel & Mašín, 2010;Suchomel & Mašín, 2011) or by using approximate probabilistic methods involving spatial averaging of soil properties (e.g. Brzakała & Puła, 1996;El-Ramly et al, 2002;Peschl & Schweiger, 2003;Cho, 2007;Suchomel & Mašín, 2010;Suchomel & Mašín, 2011).…”

Section: Introductionmentioning

confidence: 99%

The influence of experimental and sampling uncertainties on the probability of unsatisfactory performance in geotechnical applications

Maš́ın

2015

Géotechnique

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While the effect of spatial variability on the probability of unsatisfactory performance in geotechnical applications is relatively well understood, comparatively less attention has been given in the literature to the effects of experimental (measurement scatter) and sampling (insufficient number of samples) uncertainties. In this paper, a general approach is developed to incorporate experimental and sampling uncertainties into probabilistic analyses based on random field methods. It is shown that, when compared with the standard approach which attributes the measured total soil variability to spatial variability, consideration of experimental uncertainty may significantly reduce the calculated probability of unsatisfactory performance. It is argued that this may be one of the reasons for an overestimation of the probability of unsatisfactory performance in geotechnical probabilistic simulations (another important reason is the spatial averaging of soil properties). Evaluation of the sampling uncertainty reveals that, although a relatively large number of samples is needed for spatial variability characterisation, a limited number of samples is sufficient to quantify the experimental uncertainty. It is pointed out that no adjustments of the existing random field-based software are needed to consider the additional uncertainties. To illustrate the proposed approach, two extensive experimental data sets on sand are presented: one reflecting total variability and the other quantifying experimental uncertainty. A hypoplastic model is calibrated against the two data sets and adopted in random field analyses of strip footing settlement.

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Material Spatial Variability and Slope Stability for Weak Rock Masses

Cited by 52 publications

References 10 publications

Effects of Anisotropy and Saturation on Geomechanical Behavior of Mudstone

Effects of Anisotropy and Saturation on Geomechanical Behavior of Mudstone

Geomechanical characterization of a heterogenous rock mass using geological and laboratory test results: a case study of the Niobec Mine, Quebec (Canada)

The influence of experimental and sampling uncertainties on the probability of unsatisfactory performance in geotechnical applications

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