rock slope stability analysis


Doug Stead, Andrea Wolter, in Journal of Structural Geology, 2015. Socioeconomic Impact: as we note above, CMF in the glacier environment have been responsible for a number of major natural disasters in mountain regions since 1940. So the projections of their normal lines will tend to form clusters as shown in Figure 6.9. swedge cesdb software 3d geotechnical engineering The histogram moment of order 2 about the origin is given by, If we wish to know the fracture tensor in some specific direction, p, the directional fracture tensor component for fracture set m is, In the above equation, the integral is over fracture orientations, and np is the projection of a fracture at angle i onto vector p. This projection is given by np2={||1||||p||cos}2, where is the angle between and p, and ||p|| is the length of p. Note that the integral is the second histogram moment about the origin of angles, so it becomes, and the final equation for the fracture tensor component in the p direction for fracture set m is, We want the fracture tensor component for all sets of fractures, this will be. 2). Hoek and Bray (Hoek & Bray, 1981) gave an analytical expression for the factor of safety of rock mass against the planar mode of failure using a limit equilibrium approach.

Tectonic effects on roughness, such as slickensides and polishing, have been recognised as indicators of residual strength and the need for testing the shear strength in the appropriate direction with respect to surface structures noted. For configurations where centres of gravity were located in the upper (see the schematic diagram in Fig. The 2013 population of Huaraz exceeds 100,000. In addition, probabilistic slope stability analysis and probabilistic back-analysis was applied to landslides which occurred at the Arakli-Tasonu quarry, NE Turkey, on October 3, 2005, March 20, 2006, and October 19, 2006. rs3 geotechpedia geoengineer geotechnical Hazard Assessment: the complexity of CMFs in the glacial environment has important implications for hazard assessment (Huggel etal., 2004a,b). 7. Fig. Any attempt to understand slope-failure patterns requires first an understanding of the rock strength and deformability, bedding, foliation, joints and faults and their orientations and conditions; these factors control the overall ability of a slope to resist the stresses acting on it, and therefore also determine the geometry that a slope can maintain.

This corresponds to the location of the large landslides mapped in the region (El Bedoui et al., 2011). Warming may result from changes in snow and ice cover ice during the retreat of glaciers (c.f. Rather, it is more likely that the effect is (1) pulse-like; (2) will exhibit (possibly multiple and offset) lag times; (3) will exhibit a peak at some point; and (4) will then decay as susceptible sites are successively mobilized. New interpretation of the famous Bunzkgele case study (Austria) based on field work and simulation to update (Sausgruber et al., 2010) the interpretation by Zischinsky (1969). Fig.

With regard to runout, uncertainty about the volume and flow behavior of initially included and entrained ice and snow presents a major difficulty in the analysis of mobility (Evans etal., 2009a; Schneider etal., 2010). Plane failure of rock slope: (A) sliding of rock mass along planar failure and (B) 2D representation of planar failure. This surface is affected not only by two generations of regional folds, producing complex, metre-to decametre-scale dome-and-basin to crescent-and-mushroom 12 (Ramsay, 1967) or K (Thiessen and Means, 1980) type interference patterns (Fig. Some attempt using distinct-element model start to show interesting results (Preh et al., 2003; Stead and Coggan, 2012; Stead et al., 2012). Assuming there are m fracture sets, the fracture tensor in 3-D is defined as, In the above equation, is the fracture density (number per unit volume), r is the radius of a circular fracture, ni and nj are the outward normal components in the i and j directions, f(n,r) is the joint probability density function for n and r, and /2 is the solid angle corresponding to the surface of a unit hemisphere (radius=1). From: Integrating Disaster Science and Management, 2018, Subhadeep Metya, Neeraj Chaudhary, in Modeling in Geotechnical Engineering, 2021. However, in hard rock, failure plane is never smooth (Fig. ScienceDirect is a registered trademark of Elsevier B.V. ScienceDirect is a registered trademark of Elsevier B.V. When we deal with fractured rock masses, we need no such relationship as long as we do not attempt to infer a stress or strain direction directly from the anisotropy of rock blocks. Shear testing of Saw-tooth specimen (A) Shearing on a saw-tooth specimen and (B) Patton's shear strength graph. A key to analyzing rock mass failure is achieving an understanding of the geometry of rock mass discontinuities. 9b shows the fault exposed within the mine and the drag folding. Fig. The type of rock failure is governed by the pattern of discontinuity. This chapter closes with a review of risk management strategies as applied to bedrock landslides. We can still glean information that can aid in many rock mass stability studies, from rock slope stability to subsurface rock mass behavior to groundwater flow. In this study, rock slope stability analysis, especially probability analyzes will be reviewed. Just remember that engineering practice usually uses a lower hemisphere projection. Modification of Fleuty (1964) fold classification diagram to indicate slope stability and failure complexity. (Sharma et al., 1995) modified the approach for inclined top and inclined tension crack. FIGURE 16.21. Folding in two directions and the presence of interference folds has been shown to influence the complexity of slope deformations within landslides and, in combination with natural release surfaces, may explain commonly observed multiple block-type movement. Figure 6.11. Theoretically, these methods have some shortcomings embedded in it. The South Peak area is still unstable and subject to ongoing monitoring. Nevertheless, these simulations are not able to fully reproduce the structures developing within the slope. (2013) on the 1903 Frank Slide area in Alberta, Canada (Fig. Despite all these techniques, the use of the factor of safety is still the most commonly adopted method to analyze the stability analysis. (a) the urban area of Yungay is outlined by a white line. 13c), respectively. Fig. 8). Fischer et al., 2006), as well as the direct effects of atmospheric temperatures. Open folds may show the typical transverse, longitudinal, and conjugate discontinuities associated with folding, whereas tight and isoclinal folds may develop foliation and cleavage, a sign of increased damage. 3.

Furthermore, we can find no information on fracture dips. Folding plays a vital role in providing what are referred to as geologic release surfaces for rock slope failures on the sides (lateral release), at the back (rear release), and on the base (basal plane) of failure blocks.

Charles E. Glass Ph.D., P.E., in Interpreting Aerial Photographs to Identify Natural Hazards, 2013. Figure 6.8 shows such an imaginary sphere. At regional scale, Guglielmi and Cappa (2010), by modeling cohesion loss as a function of plastic strain, showed that the extent of destabilized area at La Clapire increases when the frictional component of strength begins to mobilize. Note the seepage at the fold hinge. We suggest that sedimentary structures, such as sole marks, flute casts, concretions, and ripple marks, also may have a significant influence on local or micro-to meso-scale roughness, and hence affect global rock slope behaviour. Following are the conditions of plane failure: (a) discontinuity plane must strike slope face within 20 degree and (b) angle of failure plane must be more than angle of internal friction (Fig. In addition, the effect of probabilistic distribution of persistence was investigated using a parametric method. (2012) recently pointed out, no study has been published to date that shows an unambiguous link between atmospheric warming and an increase in the magnitude and/or frequency of CMF in the mountain glacial environment. The folding of sedimentary rock sequences has numerous and varied effects on both natural and open pit slope stability (Fig. Patton's demonstrated the influence of roughness on shear strength by conducting a direct shear test on a saw-tooth specimen (Fig. Lastly, in the Kedarnath floods, India, of 2013, >1,000 people lost their lives when a monsoon-triggered glacial debris flood overran the pilgrim town of Kedernath (Evans and Delaney, unpublished data) (Figure16.23). On the other hand, many researchers have also devoted a great number of contributions in developing a probabilistic method for analyzing the stability of a rock slope (Li, Zhou, Lu, & Jiang, 2009; Ma et al., 2019; Metya & Bhattacharya, 2013, 2016, 2020; Park, Um, Woo, & Kim, 2012; Ya-Fen, Yun-Yao, Hsein, & Der-Her, 2012). 6, for example, shows the sliding scar morphology of the 1963 Vajont Slide in Italy. This can be visualized by looking at Figure 6.10. I have put you through all of this derivation so that, if you care, you can program the above equations and solve for the fracture tensor yourself. In addition, transient river damming may be an important process of major CMFs as hypothesized in the Parraguire case described by Casassa and Marangunic (1993). Limit equilibrium method and strength reduction method are generally used to determine the factor of safety. Coarse approximations though they may be, your efforts will be appreciated. Rock slopes fail generally into these five modes namely planar, wedge, circular, toppling, and buckling (Hocking, 1976; Hoek & Bray, 1981; Kliche, 1999; Lee & Wang, 2011; Ramamurthy, 2014; Tang, Yong, & Ez Eldin, 2017).

The SLOPESIM code was utilized to find the paths of minimum SM and achieve probabilistic failure analysis of a jointed rock slope.

In Figure 6.8, I have used the upper hemisphere for clarity to demonstrate this projection. An additional issue regarding runout and mobility is the volume of entrainment of glacial and alluvial materials from the path of a given CMF, which is a strong determinant on modeling outcome (Evans etal., 2009a). Another example of structural analysis associated with natural slope failures is that conducted by Humair etal.

(2009a) concluded that the death toll of the 1970 event was approximately 6,000 and that total life loss in the two events did not exceed 7,000 people (Figure16.22). More recently, the 2012 Gayari icedebris avalanche, Pakistan (Schneider etal., 2013) buried a Pakistan army camp with the loss of 128 soldiers (Figure16.5). Only one set of parallel discontinuities with varying persistence was examined in their study. Modification of fold tightness classification, showing how damage increases with increasing fold tightness (after Fossen, 2010). The notion of representative volume element (RVE) of jointed rock masses was proposed by Pariseau et al. Also, these two methods are quite convenient to analyze 2D problem of failures. Nevertheless, the application of each method depends on the required model resolution needed to simulate the relevant slope, material characteristics and fabrics. If the fracture radius is not correlated with the fracture orientation, the joint probability density function, f(n,r) can be uncoupled so that f(n,r)=f(n)f(r). FIGURE16.23. Several modeling examples show that shear strain, displacement, tensile failure location, can be calculated at the same place in the slope as observed in the field (Agliardi et al., 2001, 2009a; Ambrosi and Crosta, 2011; Baro et al., 2005; Brideau et al., 2006; Eberhardt, 2008; Eberhardt et al., 2004; Kinakin and Stead, 2005; Sausgruber et al., 2010). The fracture tensor approach was first formulated by Oda2.

The values input parameters, shear strength parameters, and depth of the water in the tension crack used in these analyses are obtained by probabilistic back-analyses. (2013) that higher tensile cracking arises from lower discontinuity persistence. Rock-slope stability and long-term equilibrium slope angles are controlled primarily by rock-mass properties. Both ways will get us to pretty much the same place, but the first (concentrating on fractures) is probably more important for fluid flow, whereas the second (concentrating on rock blocks between fractures) is probably more important for rock mass slope stability. The same authors analyzed the seasonal deformation trends of the Randa rockslide adopting a thermo-mechanical DEM approach. The fracture pattern of Figure 6.9 has only 25 rock blocks. Such failures are described in surface coal mines, where repeated strata of arenaceous and argillaceous rock masses dip into the slope (Benko, 1997). In the analysis of initial failure, in addition to the geological and geotechnical characterization of the source rock mass, quantification of the role of the degradation of high-altitude permafrost in rock slope stability presents an analytical challenge (e.g., Gruber and Haeberli, 2007; Fischer etal., 2010; Krautblatter etal., 2013). Jomelli etal., 2007) and can be complicated by at least two factors. Under the purview of stability analysis of a rock slope, the strength values are, in recent years, been regarded as a variable in the range from the peak strength to the residual strength (Bhattacharya, Chowdhury, & Metya, 2019; Metya, Bhattacharya, & Chowdhury, 2016a, 2016b), as because the sliding failure of a rock mass is generally a progressive failure process (Metya, Bhattacharya, & Chowdhury, 2016c; Metya, Dey, Bhattacharya, & Chowdhury, 2019; Pan, Sun, Wu, & L, 2017; Scholts & Donz, 2012) and the softening behavior of a rock mass is also been demonstrated through a series of laboratory tests (Casagrande, Buzzi, Giacomini, Lambert, & Fenton, 2018; Sow et al., 2017; Tiwari & Latha, 2019). Three different sliding block geometries were investigated, that is, with block centres of gravity located in the upper part (Fig.

These include the formation and failure of natural dams and the generation of displacement waves, which in turn may generate a CMF. 2013 ASTER image of the city of Huaraz in the Peruvian Andes. We suggest that the features of a conventional fold classification, such as Fleuty (1964) or Ramsay (1967), should be considered with respect to how they influence rock slope stability (Fig. Copyright 2022 Elsevier B.V. or its licensors or contributors. Among these, Ling and Cheng (Ling & Cheng, 1997) also gave the formulation using coulomb criteria for large width using plane strain conditions. In the 1961 Peru Census, the population of Yungay was recorded as being 3,543, a population density of 9,980 p/km2. (2006, 2012) provided a comprehensive overview of the innovative application and of the most representative case studies where DEM modeling was successfully applied. Cruden and Krahn (1978) described the presence of slickensides on folded bedding surfaces, as well as minor thrusts, which controlled the Frank Slide.

However, even in circumstances when knowledge about a historical event is well constrained, the interpretation of coarse rubbly deposits may not be straightforward (cf. 8. Focus in rock engineering has been on the use of roughness measures such as the Joint Roughness Coefficient, JRC (Barton, 1976, 2011; Barton and Choubey, 1977).

The association of kinematic rock slope failure modes with anticlinal folding has been discussed by Badger (2002), who described the relationship between failure (planar/toppling) and the relative location of the rock slope and discontinuity sets commonly associated with folded, bedded units.