JOURNAL OF ROCK MECHANICS

JOURNAL OF ROCK MECHANICS

Modeling of Slide-Head-Toppling Failure Using Limit Equilibrium and Finite Element Methods

Document Type : Original Article

Authors
Hassan Sarfaraz
Mohadeseh Sarlak
University of Tehran
10.22034/irsrm.2023.400358.1536
Abstract
Toppling failure is one of the most common rock slope instabilities. If the discontinuity failure is triggered by an external natural or artificial factor, it is called a secondary toppling failure. One of the most important types of secondary toppling failure is slide-head-toppling. In this failure, in the crest region, rock blocks experience toppling, leading to sliding failure in soil mass due to the resulting pressures. In the case of pure flexural toppling failure at the crest, rock blocks in the upper crest section undergo tension-induced bending and toppling. Consequently, the underlying soil mass experiences sliding under imposed pressures. In instances of pure block toppling failure at the crest, due to the presence of secondary joints, the rock blocks cannot withstand tensile stresses. As a result of the pressure exerted by the overlying blocks, they undergo toppling or sliding. Similarly, in cases of pure block-flexural toppling failure at the crest, under the pressure resulting from the weight of the overlying blocks, half of the blocks experience tensile-induced flexural toppling, while the remaining half separate from the secondary joint locations, leading to block toppling. Subsequently, all blocks topple against each other, resulting in sliding within the soil mass. Using the limit equilibrium software, SLIDE software, physical models within the soil mass are analyzed as developed by Amini et al. (2018), and the obtained results are compared with the analytical method. The outcomes from this software exhibit a commendable concurrence with the results derived from physical modeling and analytical approach. Additionally, using the numerical software Phase2, the slide-head-toppling failure was numerically modeled, and the safety factor for each model was calculated. Moreover, the findings indicate that the sliding surface within block toppling is along cross joints, and the sliding surface within flexural toppling occurs at an angle ranging between 5 to 15 degrees with respect to the perpendicular to the stratification plane. The critical sliding surface within the soil mass initiates approximately from the mid-height of the rock block in contact with the soil, extending to the toe of the slope.
Keywords
Rock Slope
Slide-Head-Toppling
Critical Sliding Failure
Limit Equilibrium Method
Slide Software
Phase 2 Software
Subjects
[1]         L. Müller, “New considerations on the Vaiont slide,” Rock Mech Eng Geol, vol. 6, pp. 1–91, 1968.
[2]         D. C. Wyllie, C. W. Mah, and E. Hoek, Rock slope engineering : civil and mining. Spon Press, 2004.
[3]         D. P. Adhikary, A. V. Dyskin, R. J. Jewell, and D. P. Stewart, “A study of the mechanism of flexural toppling failure of rock slopes,” Rock Mech. Rock Eng., vol. 30, no. 2, pp. 75–93, 1997.
[4]         D. P. Adhikary and A. V. Dyskin, “Modelling of progressive and instantaneous failures of foliated rock slopes,” Rock Mech. Rock Eng., vol. 40, no. 4, pp. 349–362, Aug. 2007.
[5]         A. K. Alzo’ubi, C. D. Martin, and D. M. Cruden, “Influence of tensile strength on toppling failure in centrifuge tests,” Int. J. Rock Mech. Min. Sci., vol. 47, no. 6, pp. 974–982, 2010.
[6]         A. Majdi and M. Amini, “Analysis of geo-structural defects in flexural toppling failure,” Int. J. Rock Mech. Min. Sci., vol. 48, no. 2, pp. 175–186, 2011.
[7]         M. Amini, A. Majdi, and Ö. Aydan, “Stability Analysis and the Stabilisation of Flexural Toppling Failure,” Rock Mech. Rock Eng., vol. 42, no. 5, pp. 751–782, Oct. 2009.
[8]         M. Amini, A. Majdi, and M. A. Veshadi, “Stability analysis of rock slopes against block-flexure toppling failure,” Rock Mech. Rock Eng., vol. 45, no. 4, pp. 519–532, Jul. 2012.
[9]         H. Sarfaraz and M. Amini, “Numerical modeling of rock slopes with a potential of block-flexural toppling failure,” J. Min. Environ., vol. 11, no. 1, pp. 247–259, 2020.
[10]       H. Sarfaraz, “Stability analysis of block-flexural toppling of rock blocks with round edges,” J. Min. Environ., vol. 11, no. 4, pp. 1217–1229, 2020.
[11]       H. Sarfaraz, M. Sarlak, F. Ashoor, and E. Amini, “Block Toppling Stability of Rock Block with Rounded Edges using Sarma Approach,” J. Min. Environ., vol. 14, no. 1, pp. 341–353, 2023.
[12]       Y. Zheng, C. Chen, T. Liu, K. Xia, and X. Liu, “Stability analysis of rock slopes against sliding or flexural-toppling failure,” Bull. Eng. Geol. Environ., vol. 77, no. 4, pp. 1383–1403, May 2018.
[13]       E. Mohtarami, A. Jafari, and M. Amini, “Stability analysis of slopes against combined circular-toppling failure,” Int. J. Rock Mech. Min. Sci., vol. 67, pp. 43–56, 2014.
[14]       M. Tsesarsky and Y. H. Hatzor, “Kinematics of overhanging slopes in discontinuous rock,” J. Geotech. Geoenvironmental Eng., vol. 135, no. 8, pp. 1122–1129, 2009.
[15]       H. Haghgouei, A. R. Kargar, M. Amini, and K. Esmaeili, “An analytical solution for analysis of toppling-slumping failure in rock slopes,” Eng. Geol., vol. 265, p. 105396, 2020.
[16]       H. Sarfaraz, A. R. Bahrami, and R. Samani, “Numerical Modelling of Slide-Head-Toppling Failure using FEM and DEM Methods,” 2022.
[17]       H. Sarfaraz, “A simple theoretical approach for analysis of slide-toe-toppling failure,” J. Cent. South Univ., vol. 27, no. 9, 2020.
[18]       H. Sarfaraz and M. Amini, “Numerical Simulation of Slide-Toe-Toppling Failure Using Distinct Element Method and Finite Element Method,” Geotech. Geol. Eng., vol. 38, no. 2, pp. 2199–2212, 2020.
[19]       M. Frayssines and D. Hantz, “Modelling and back-analysing failures in steep limestone cliffs,” Int. J. Rock Mech. Min. Sci., vol. 46, no. 7, pp. 1115–1123, 2009.
[20]       R. S. Evans, “An analysis of secondary toppling rock failures--the stress redistribution method,” Q. J. Eng. Geol. Hydrogeol., vol. 14, no. 2, pp. 77–86, 1981.
[21]       S. L. Nichol, O. Hungr, and S. G. Evans, “Large-scale brittle and ductile toppling of rock slopes,” Can. Geotech. J., vol. 39, no. 4, pp. 773–788, Aug. 2002.
[22]       L. R. Alejano, I. Gómez-Márquez, and R. Martínez-Alegría, “Analysis of a complex toppling-circular slope failure,” Eng. Geol., vol. 114, no. 1–2, pp. 93–104, 2010.
[23]       M. Amini, A. Ardestani, and M. H. Khosravi, “Stability analysis of slide-toe-toppling failure,” Eng. Geol., vol. 228, pp. 82–96, 2017.
[24]       M. Amini and A. Ardestani, “Stability analysis of the north-eastern slope of Daralou copper open pit mine against a secondary toppling failure,” Eng. Geol., vol. 249, pp. 89–101, 2019.
[25]       M. Amini, H. Sarfaraz, and K. Esmaeili, “Stability analysis of slopes with a potential of slide-head-toppling failure,” Int. J. Rock Mech. Min. Sci., vol. 112, pp. 108–121, Dec. 2018.
[26]       H. Sarfaraz, M. H. Khosravi, and M. Amini, “Numerical Analysis of Slide-Head-Toppling Failure,” J. Min. Enviroment, vol. 10, no. 4, pp. 1001–1011, 2019.
[27]         M. H. Khosravi, H. Sarfaraz, M. Esmailvandi, and T. Pipatpongsa, “A Numerical Analysis on the Performance of Counterweight Balance on the Stability of Undercut Slopes,” Int. J. Min. Geo-Engineering, vol. 51, no. 1, pp. 63–69, 2017
JOURNAL OF ROCK MECHANICS
Volume 7, Issue 3
Autumn 2023
Pages 61-75