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# A General Solution for Estimating the Safety Factor of Bimslopes

Authors:
• Rahsaz Tarh Consulting Engineers Company (مهندسین مشاور رهسازطرح)
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## Abstract and Figures

Bimslopes are slopes underlain by block-in-matrix rocks/soils (bimrocks/bimsoils), which are heterogeneous geomaterials with complex behavior. Abundant uncertainties in the mechanical, spatial, and geological nature of bimslopes make it difficult to estimate stability conditions of bimslopes. In this paper, some factors affecting the stability of bimslopes are investigated using the finite-element method. The main contributory factors include Volumetric Block Proportion (VBP), the inclination of blocks, and the strength of matrix/block interfaces. By performance of sensitivity analysis on these factors, a statistically significant equation was obtained to estimate the safety factor of bimslopes using the multivariate regression method. The influence of block configurations and groundwater levels on the stability of bimslopes was then investigated to more confidently use the multivariate equation. Finally, to check the validity of procedures presented in this paper, a real failed bimslope in the Sungun mine (Iran) was investigated. The acceptable results from the Sungun analysis demonstrated the safety factor of bimslopes can be estimated using the practical solution presented in this paper.
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Rock Mechanics and Rock Engineering (2022) 55:7675–7693
https://doi.org/10.1007/s00603-022-03050-z
ORIGINAL PAPER
A General Solution forEstimating theSafety Factor ofBimslopes
Received: 20 May 2022 / Accepted: 24 August 2022 / Published online: 13 September 2022
© The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature 2022
Abstract
Bimslopes are slopes underlain by block-in-matrix rocks/soils (bimrocks/bimsoils), which are heterogeneous geomateri-
als with complex behavior. Abundant uncertainties in the mechanical, spatial, and geological nature of bimslopes make
it diﬃcult to estimate stability conditions of bimslopes. In this paper, some factors aﬀecting the stability of bimslopes are
investigated using the ﬁnite-element method. The main contributory factors include Volumetric Block Proportion (VBP),
the inclination of blocks, and the strength of matrix/block interfaces. By performance of sensitivity analysis on these factors,
a statistically signiﬁcant equation was obtained to estimate the safety factor of bimslopes using the multivariate regression
method. The inﬂuence of block conﬁgurations and groundwater levels on the stability of bimslopes was then investigated
to more conﬁdently use the multivariate equation. Finally, to check the validity of procedures presented in this paper, a real
failed bimslope in the Sungun mine (Iran) was investigated. The acceptable results from the Sungun analysis demonstrated
the safety factor of bimslopes can be estimated using the practical solution presented in this paper.
Highlights
Development of more than 1300 numerical models to analyze the key factors aﬀecting the stability of block-in-matrix
slopes (bimslopes).
Investigation of the inﬂuence of volumetric block proportion, the inclination of blocks, and strength of matrix/block
interface on the safety factor of bimslopes.
Consideration of the substantial uncertainties aﬀecting the analysis of bimslopes.
Presentation of the results of research in the form of applied schemes and tables.
Provision of a practical procedure and equation for estimating the safety factor of bimslopes.
Keywords Bimrocks· Bimslopes· Slope stability· Numerical modeling· Sensitivity analysis
Mehdi Amini
mamini@thurber.ca
Edmund Medley
emedley@bimrocks.com
s.hossaini@unsw.edu.au
1 School ofMining Engineering, College ofEngineering,
University ofTehran, Northern Kargar Street, Tehran, Iran
2 Thurber Engineering Ltd., Vancouver, Canada
3 Terraphase Engineering, Oakland, CA94612, USA
4 RahsazTarh Consulting Engineers, Tehran, Iran
5 School ofMinerals andEnergy Resources Engineering,
UNSW, Sydney, Australia
... Under the rainfall conditions, an erosion failure was observed in the soil-rock mixture slope, and the increasing rock content would densify the soil skeletons, decrease the migration of fine particles, and finally weaken the erosion effect [39]. The groundwater level also has influences on the stability of bimslopes, i.e., the normalized safety factor was recommended to reduce by 25% when the bimslopes was fully saturated [40]. Large-deformation failure mechanisms of soil-rock mixture slopes were analyzed by Zhao et al. [41]. ...
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