Refined Approaches for Estimating the Strength of Rock Blocks

Stavrou, Anastasios; Vazaios, Ioannis; Murphy, William M.; Vlachopoulos, Nicholas

doi:10.1007/s10706-019-00989-9

Cited by 19 publications

(4 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A Trigon approach developed by Gao et al ( 2015 ) was used to generate blocks in the model, as this approach can be capable of reproducing the natural fracturing processes (e.g., crack initiation, propagation, and coalescence) of rock masses without adopting complicated constitutive models (Chen et al 2016 ; Hu et al 2020 ; Stavrou et al 2019 ; Yang et al 2017 ). In the Trigon approach, a rock mass is represented as an assembly of triangular blocks bonded together by contacts (Gao et al 2015 ).…”

Section: Numerical Modelingmentioning

confidence: 99%

Evaluation of the performance of yielding rockbolts during rockbursts using numerical modeling method

Wang

Apel

et al. 2022

Int J Coal Sci Technol

View full text Add to dashboard Cite

The assessment of yielding rockbolt performance during rockbursts with actual seismic loading is essential for rockburst supporting designs. In this paper, two types of yielding rockbolts (D-bolt and Roofex) and the fully resin-grouted rebar bolt are modeled via the “rockbolt” element in universal distinct element code (UDEC) after an exact calibration procedure. A two-dimensional (2D) model of a deep tunnel is built to fully evaluate the performance (e.g., capacity of energy-absorption and control of rock damage) of yielding and traditional rockbolts based on the simulated rockbursts. The influence of different rockburst magnitudes is also studied. The results suggest that the D-bolt can effectively control and mitigate rockburst damage during a weak rockburst because of its high strength and deformation capacity. The Roofex is too “soft” or “smooth” to limit the movement of ejected rocks and restrain the large deformation, although it has an excellent deformation capacity. The resin-grouted rebar bolt can maintain a high axial force level during rockbursts but is easy to break during dynamic shocks, which fails to control rapid rock bulking or ejection. Three types of rockbolts cannot control the large deformation and mitigate rockburst damage effectively during violent rockbursts. The rockburst damage severity can be significantly reduced by additional support with cable bolts. This study highlights the effectiveness of numerical modeling methods in assessing the complex performance of yielding rockbolts during rockbursts, which can provide some references to improve and optimize the design of rock supporting in burst-prone grounds.

show abstract

Section: Numerical Modelingmentioning

confidence: 99%

Evaluation of the performance of yielding rockbolts during rockbursts using numerical modeling method

Wang

Apel

et al. 2022

Int J Coal Sci Technol

View full text Add to dashboard Cite

show abstract

“…The large range in the physical and mechanical properties typically observed for volcanic rocks of the same porosity is often considered to be the result of microand sample-scale heterogeneities (e.g., Heap and Violay, 2021). Numerical experiments using modelling software Fast Lagrangian Analysis of Continua (FLAC; Itasca Consulting Group Ltd) (Villeneuve et al, 2012), UDEC and 3DEC (Distinct Element Modelling; Itasca Consulting Group Ltd) (Ghazvinian et al, 2014;Stavrou et al, 2019;Xu et al, 2020), Rock Failure Process Analysis (RFPA; Mechsoft Technology) (Tang et al, 2000(Tang et al, , 2007Zhu, 2008), and Particle Flow Code (PFC; Itasca Consulting Group Ltd) (Peng et al, 2017;Liakas et al, 2017) have also demonstrated that microstructural heterogeneity leads to a reduction in rock strength. Numerical experiments have also shown that pore size and shape (Heap et al, 2014b;Griffiths et al, 2017;Heap et al, 2021c) and crystal content (Heap et al, 2016) can influence mechanical behaviour of volcanic rocks.…”

Section: Introductionmentioning

confidence: 99%

The influence of heterogeneity on the strength of volcanic rocks and the stability of lava domes

Heap,

Harnett,

Nazarbayov

et al. 2023

Bull Volcanol

View full text Add to dashboard Cite

The collapse of lava domes, inherently heterogeneous structures, represents a significant volcanic hazard.Numerical and analogue models designed to model dome instability and collapse have incorporated heterogeneity 2 in the form of discrete zones with homogeneous properties. Based on an assessment of dome rock heterogeneity, we explore whether material property heterogeneity ("diffuse" heterogeneity) within these discrete zones can promote dome instability. X-ray computed tomography shows that dome samples are characterised by high microstructural heterogeneities; e.g., porosity varies from 0.07 to 0.20 over millimetric lengthscales. To explore how microstructural heterogeneity influences sample-scale strength, we performed numerical simulations using Rock Failure and Process Analysis. The mean mechanical properties of the numerical samples were constant, and we introduced heterogeneity by varying their distribution using a Weibull probability function. The models show that increasing heterogeneity can reduce sample-scale strength by more than a factor of two. To explore the influence of dome-scale heterogeneity, we numerically generated lava domes in Particle Flow Code. The domes have the same bulk strength but are characterised by different degrees of heterogeneity by varying the distribution of cohesion using a Weibull probability function. The models show that a greater degree of heterogeneity induces higher dome-scale displacements and that, when there is also a discrete weakened zone, the addition of diffuse heterogeneity leads to more widely distributed deformation. Therefore, alongside discrete zones defined by different material properties, we find that the diffuse heterogeneity inherent to a dome is sufficient to compromise dome stability and should be incorporated in future modelling endeavours.

show abstract

“…DEM GBMs have also proven to be a useful tool to scale the mechanical behaviour of intact rock at the laboratory scale to the behaviour of rock blocks at an engineering scale (Stavrou and Murphy 2018;Stavrou et al 2019). The effects of thermo-mechanical loading have also been demonstrated in GBMs.…”

Section: Introductionmentioning

confidence: 99%

Laboratory Experiments and Grain Based Discrete Element Numerical Simulations Investigating the Thermo-Mechanical Behaviour of Sandstone

et al. 2021

Self Cite

View full text Add to dashboard Cite

Thermo-mechanical loading can occur in numerous engineering geological environments, from both natural and anthropogenic sources. Different minerals and micro-defects in rock cause heterogeneity at a grain scale, affecting the mechanical and thermal properties of the material. Changes in strength and stiffness can occur from exposure to elevated temperatures, with the accumulation of localised stresses resulting in thermally induced micro-cracking within the rock. In this study we investigated thermal micro-cracking at a grain scale through both laboratory experiments and their numerical simulations. We performed laboratory triaxial experiments on specimens of fine-grained sandstone at a confining pressure of 5 MPa and room temperature (20$$^{\circ }\hbox {C}$$ ∘ C ), as well as heating to 50$$^{\circ }\hbox {C}$$ ∘ C , 75$$^{\circ }\hbox {C}$$ ∘ C and 100$$^{\circ }\hbox {C}$$ ∘ C prior to mechanical loading. The laboratory experiments were then replicated using discrete element method simulations. The geometry and granular structure of the sandstone was replicated using a Voronoi tessellation scheme to produce a grain based model. Strength and stiffness properties of the Voronoi contacts were calibrated to the laboratory specimens. Grain scale thermal properties were applied to the grain based models according to mineral percentages obtained from quantitative X-ray diffraction analysis on laboratory specimens. Thermo-mechanically coupled modelling was then undertaken to reproduce the thermal loading rates used in the laboratory, before applying a mechanical load in the models until failure. Laboratory results show a reduction of up to 15% peak strength with increasing thermal loading between room temperature and 100$$^{\circ }\hbox {C}$$ ∘ C , and micro-structural analysis shows the development of thermally induced micro-cracking in laboratory specimens. The mechanical numerical simulations calibrate well with the laboratory results, and introducing coupled thermal loading to the simulations shows the development of localised stresses within the models, leading to the formation of thermally induced micro-cracks and strength reduction upon mechanical loading.

show abstract

Refined Approaches for Estimating the Strength of Rock Blocks

Cited by 19 publications

References 35 publications

Evaluation of the performance of yielding rockbolts during rockbursts using numerical modeling method

Evaluation of the performance of yielding rockbolts during rockbursts using numerical modeling method

The influence of heterogeneity on the strength of volcanic rocks and the stability of lava domes

Laboratory Experiments and Grain Based Discrete Element Numerical Simulations Investigating the Thermo-Mechanical Behaviour of Sandstone

Contact Info

Product

Resources

About