Natural Rock Slope Research Articles

Rock slope deformation analysis of the powerhouse cut-slope at Middle Bhotekoshi Hydroelectric Project in Sindhupalchok District, Central Nepal

This paper elaborates the rock slope deformation analysis in a complex rock mass i.e., metamorphic rocks. At the powerhouse of the Middle Bhotekoshi Hydroelectric Project, Sindhupalchok, Nepal, the rock slope deformation has occurred as a result of excavation of natural rock slope turning into the cut-slope. The deformation yielded by different causes were studied and analyzed by kinematic analysis, inclinometer data combining with numerical modeling. For the study and analysis of the cut-slope, geotechnical data were collected from the existing rock types of the cut-slope. At first, the kinematic analysis was carried out by using the stereonet plot in DIPS. The core logs of investigation time were reviewed and tried to prepare the geological model of this part. The finite element method was used to analyze the stability of the rock cut-slope based on the geotechnical data. Similarly, the inclinometer recorded data were used to compare with the analyzed deformation data and tried to find out the weak zone within the cut-slope. The kinematic analysis showed that the rock slope has the least probability of failure. The result showed that there was tolerable deformation on the slope based on inclinometer data but failure was observed at PSIN-1 where the weak zone is present. The deformation at PSIN-1 was found to be in the thin ductile deformed zones where rock characteristics were different which was considered not operative for the slope stability.

Inferring rockfall frequency-magnitude relationships and talus accumulation times from lichenometric study of talus deposits, Glenwood Canyon, CO, USA

Rockfall is a frequent hazard in mountainous areas of the world. Rockfall hazard assessment and mitigation design typically require design volumes of blocks and design frequencies of events. However, constraining the frequency of rockfall is challenging due to limited data, limited timespans of data collection, and difficulty of estimating dates for past rockfalls. This paper presents a study of rockfall frequency from natural rock slopes in Glenwood Canyon, Colorado using lichenometry measurements of Lecanora novomexicana and Lecidea atrobrunnea lichens from 1070 boulders from six talus deposits. The lichen ages are used to develop frequency-magnitude relationships for rockfall, to calculate recurrence intervals for selected volumes, and to estimate the time required to develop the observed talus deposits. Power laws fit to frequency-magnitude distributions of lichen ages yield b parameters ranging from −0.61 to −1.04. Based on these distributions, recurrence intervals for selected rockfall magnitudes include: sub-annual to annual for 0.1 m3, a few years to decades for 1 m3, and several decades for 10 m3 rockfalls. These estimated recurrence intervals appear to agree with observed signs of rockfall activity from the studied slopes and with rockfall data from the limited historical record for Glenwood Canyon. Mapped lichen ages indicate no preferential spatial distribution of rockfalls, implying the majority of rockfall events are small relative to the scale of the deposit. A comparison of the estimated volumetric rockfall accumulation rates with estimated total talus deposit volumes suggests that each of the studied deposits has a depositional history extending back longer than the beginning of the Holocene.

In-depth field survey of a rockslide detachment surface to recognise the occurrence of gravity-induced cracking

This work describes field evidence of gravity-induced cracking that has been identified on the failure scar of a small rockslide (volume = 6–7 m3) that occurred in March 2004 in the Rosandra Valley near the town of Trieste (north-eastern Italy). This shallow rock slope failure involved a limestone slope that was re-profiled through blasting about 135 years ago for the construction of an old railway, which has now been reconverted into a cycle path. Field observations ascertained that the slope failure was characterised by a cascading rupture process in which adjacent blocks collapsed in rapid sequence as a result of the progressive breakage of a number of rock bridges (domino-like collapse), thus highlighting a progressive failure mechanism. The rock bridges were localised in eccentric positions on lateral and rear release planes and failed in tension as a result of combined tensile and bending loading conditions (tensile strength of intact rock = 5 ± 2 MPa). The rockslide was triggered by cyclic loading related to freeze-thaw (ice jacking) that occurred over some consecutive days of daily snowmelt and nocturnal frost. The recognition of newly formed fractures also proves the current progressive development of 3D rupture surfaces of some unstable blocks susceptible to failure. This study provides innovative content to detect gravity-induced cracking in the field, which is an important precursory sign relating to the progressive failure of rock slopes. Gravity-induced cracks can be distinguished from pre-existing discontinuities for their more irregular profile (zigzag pattern), rougher surface, lower persistence and potentially different orientation. This study also provides some new insights into the step-path failure process of steep rock slopes. The mechanical process of initiation, growing and coalescence of gravity-induced fractures is strongly time- and stress-dependent. In the absence of external changing factors that profoundly modify the acting stress state (for instance, engineering countermeasures), progressive failure is a dynamic and irreversible process. For excavated slopes, the creation of a new rock face may abruptly provide the kinematic freedom of potentially unstable blocks, thus determining a very quick stress redistribution. If the mechanical system is not able to redistribute the stress on resisting stiff parts without overcoming the intact rock strength, gravity-induced cracking initiates and propagates until reaching slope collapse within times that are much shorter (from hours to 100–200 years) compared to natural rock slopes subjected to long-lasting geological processes (from 1000 to 2000 up to 10,000–20,000 years).

Hazard Assessment of Rocky Slopes: An Integrated Photogrammetry–GIS Approach Including Fracture Density and Probability of Failure Data

Natural rock slopes require accurate engineering–geological characterization to determine their stability conditions. Given that a natural rock mass is often characterized by a non-uniform fracture distribution, the correct, detailed, and accurate characterization of the discontinuity pattern of the rock mass is essential. This is crucial, for example, for identifying the possibility and the probability of kinematic releases. In addition, complete stability analyses of possible rockfall events should be performed and used to create hazard maps capable of identifying the most dangerous parts of a rock mass. This paper shows a working approach that combines traditional geological surveys and remote sensing techniques for engineering–geological investigations in a natural rock slope in Northern Italy. Discontinuities were identified and mapped in a deterministic way by using semi-automatic procedures that were based on detailed 3D Unmanned Aerial Vehicle photogrammetric-based point cloud data and provided georeferenced representations of thousands of fractures. In this way, detailed documentation of the geo-mechanical and geo-structural characteristics of discontinuities were obtained and subsequently used to create fracture density maps. Then, traditional kinematic analyses and probabilistic stability analyses were performed using limit equilibrium methods. The results were then managed in a GIS environment to create a final hazard map that classifies different portions of the rock slope based on three factors: kinematic predisposition to rockfall (planar sliding, wedge sliding, toppling), fracture density, and probability of failure. The integration of the three hazard factors allowed the identification of the most hazardous areas through a deterministic and accurate procedure, with a high level of reliability. The adopted approach can therefore be very useful to determine the areas in which to prioritize remediation measures with the aim of reducing the level of risk.

A discrete fracture network based modeling scheme for analyzing the stability of highly fractured rock slope

Numerical investigation on stability of the rock slope with densely distributed fractures is still challenging. To overcome the large computational requirements caused by the fracture representation, material heterogeneity and mathematical nonlinearity, an efficient discrete fracture network (DFN) based modeling scheme is developed in this paper. With DFNs stochastically generated according to the statistical distributions of the fractures for resembling the natural fractured rock slope, finite element method (FEM) based strength reduction analysis is conducted for locating the critical slip surface and assessing the factor of safety, where the rock blocks are discretized as solid elements while discrete fractures are practically modeled by frictional contact interface elements. The effectiveness of the proposed approach is validated by comparison against analytical and several numerical solutions. A case study is further performed to evaluate the effects of DFN realization number and geometrical configuration on the stability of the fractured rock slope. It shows that 20 DFN realizations are sufficient to obtain a statistically convergent mean of the factor of safety. The predicted critical slip surface displays to be non-circular but linear or broken line morphology along the fracture network. The proposed numerical scheme shows to be useful and promising in investigating the deformation response and sliding failure mode in highly fractured rock slope. Massive fractures disorder the displacement distribution of the slope and influence the overall factor of safety, and the estimated factor of safety decreases with the increase ofslope height and angle, indicating the fracture distribution and slope geometric features as the prominent influential factors.

Analysis of Flexural Toppling Failure in Rock Slopes Using Discrete Element Method

Flexural toppling failure is a common failure mode of natural and artificial rock slopes, which has caused serious damage to human life and property. In this work, an advanced numerical method called the Universal Distinct Element Code (UDEC) was used to study the mechanism of flexural toppling failure. In total, more than twenty slope models were built and analyzed. Two new parameters (displacement discontinuity and transition coefficient of failure surface) were introduced to present a further understanding of flexural toppling. The results show the failure zone of rock slopes subjected to flexural toppling includes two parts: the first-order instability part (FOIP) and the independent toppling zone (ITZ). The FOIP can be further divided into two subzones: the sliding zone (SZ) and the superimposed toppling zone (STZ). The occurrence of surface deformation discontinuities is the precursor to flexural toppling failure. The first displacement discontinuity occurs on the boundary between the FOIP and the ITZ. The angle, spacing, and angle of the joints, the angle of the slope has a significant influence on the stability of anti-dip bedding rock slopes. However, they do not affect the deformation and failure pattern of the slope.

Digital image correlation–based analysis of hygroscopic expansion in Herrnholz granite

Groundwater-induced deformation of natural rock slopes is typically interpreted to be related to changes in pore pressure. Rock, however, is a porous medium that has been shown to expand on contact with water. Here, we present insights into surface deformation of free-standing 115 × 65 × 35 mm granite prisms with water continuously infiltrating from the upper surface over 16 – 24 hours under ambient laboratory environmental conditions. Digital image correlation analysis indicates a mean extensional strain due to wetting of approximately (4 – 4.7) × 10 −4 , equivalent to an internal pressure of 40 – 47 MPa, assuming linear-elastic material behaviour. Nanoscale adsorption theory indicates the contribution from adsorption of water onto free surfaces may be 18.4 MPa, while capillary condensation generates pressure up to 30.9 MPa. It is likely a majority of strains is the result of water entering micro pores with radius less than 5 nm, which account for 1.16% of the porosity. Our relatively simple experimental setup may serve as a useful tool for analyzing moisture-induced deformation in a range of geological materials.

Assessment of rock slope stability using slope stability probability classification (SSPC) system, around AlemKetema, North Shoa, Ethiopia

This research was conducted in an area around AlemKetema, North Showa, central Ethiopia; with a general objective of conducting a rock slope stability assessment on the selected natural rock slope sections. To achieve this objective, slope stability probability classification was followed to determine the stability probability conditions of slope rock mass in the study area. These classification systems mainly depend on the primary data collected from field works. As a reason, systematic and extensive fieldwork was conducted. However, secondary data was also required to characterize the general conditions of the study area and to have a deep understanding of the subject matter. In the SSPC system, ratings for the degree of weathering, intact rock strength, method of excavation, roughness condition, and infill material were given according to standards. The slope stability probability classification (SSPC) system practices three-step classification systems. These steps are exposure rock mass, reference rock mass, and slope rock mass. Following these steps, slope rock mass stability probability classifications have been carried out for 92 natural rock slope sections. The stability of slope rock mass was determined by two different approaches namely orientation-dependent and orientation independent stability. Orientation dependent stability is linked with the orientation of the discontinuities and characterized by toppling and sliding criteria, while orientation independent stability is linked with the strength of slope rock mass. Accordingly, the overall assessment indicated that 80.4% of rock slope sections showed less than 5% stability probability, 10.9% of rock slope sections showed from 5 to 49%, 6.5% showed from 50 to 95%, and the rest 2.2% of rock slope sections showed greater than 95% stability probability. All these results were compared with the visual stability assessment results. Accordingly, different stability probability maps were produced.

Assessment of Rockfall Hazard and Stabilization of Rock Slope Surface at the World Heritage Ajanta Cave

The assessment of rock fall hazard of a natural rock slope surface with ancient rock cave monuments of historic importance at World-Heritage site of Ajanta in the state of Maharashtra in India, embedded in basaltic rock formation is carried out and presented. In past the site has witnessed many small and large scale rock falls in the form of boulders which could cause the loss to the ancient rock caves of historic importance as well as en-dangering the visitor’s safety. The main cause of the rock fall is dislocation of the boulders from the natural rock surface slopes due to heavy rainfall as well as due to erosion, rock weathering, trees roots widening etc. In the present study, the rock slope surface and dislocated boulders vulnerability to failure risk is carried out with the Rockfall Hazard Rating System (RHRS) in tandem with other empirical approaches available for rock mass classification. The study using rockfall hazard rating system requires tedious field-work due to the involvement of a large number of parameters and long-stretch of the site under question. The detailed field study is carried out for the evaluation of various parameters involved in the RHRS as well as that of various empirical approaches applied. In the case of the cumulative RHRS score is more than 500 which implies that the slope surface or critical boulder site is unstable, prone to failure and need immediate attention for remedial measures. Accordingly, stabilization measures are planned on the priority basis.

Borehole monitoring of thermo-hydro-mechanical rock slope processes adjacent to an actively retreating glacier

Most natural rock slope failures result from long-term strength degradation. It is often hypothesized that glacial retreat leads to enhanced progressive damage accumulation in adjacent rock slopes, due to mechanical unloading and changes to the thermal and hydraulic boundary conditions. However, direct observations of subsurface processes in a rock slope subject to glacial retreat are rare. In this paper, we present the design, implementation, and performance of a new borehole monitoring system installed on a rock slope in fractured crystalline rock located beside the glacier tongue of the retreating Great Aletsch Glacier (Valais, Switzerland). The three vertical, 50 m deep boreholes were instrumented to continuously monitor groundwater pressure, temperature and deformation at high resolution, in order to investigate thermo-hydro-mechanical coupled slope processes that drive progressive rock mass damage. We show that the system is capable of measuring both reversible and irreversible displacements along single fractures at magnitudes ranging between 0.001 mm to >2 mm in the studied rock slope, and that it is often possible to identify drivers of these deformation signals. The transient subsurface temperature field shows clear indications of former ice occupation in form of cold temperatures preserved at depth and superimposed annual temperature cycles penetrating down to a depth of about 17 m. The variability of the pressure head in the slope is driven by annual snowmelt infiltration cycles, rainfall events, and the assumed connection to englacial water of the temperate glacier. The new and continuously growing dataset presented here will enable us to relate the changing boundary conditions caused by glacial retreat and fatigue from daily to annual thermal and hydraulic loading cycles to progressive rock mass weakening, which may ultimately result in rock slope failure.

Numerical Investigation of the Pre-collapse Behavior and Internal Damage of an Unstable Rock Slope

This paper describes the results of a 2D and 3D numerical modeling carried out on an unstable natural rock slope (volume = 110,000–335,000 m3) located in north-eastern Italy (Friuli Venezia Giulia Region). It was aimed at investigating the mechanical behavior and internal rock mass damage of the unstable slope before the collapse. The numerical simulations testify that the stability condition of the slope is close to the limit equilibrium (strength reduction factor, SRF = 1.03–1.13), as demonstrated by the considerable rock mass damage observed on the field. The overall mechanical behavior of the slope is mainly governed by the kinematic conditions of the secondary internal blocks, which, in turn, depend on the geometry and mechanical properties of the major discontinuities that delimit the adjacent blocks. Slope failure is achieved through internal rock mass damage represented by internal shear and tensile ruptures localized in correspondence with over-stressed zones. The failure mechanism is characterized by sliding along pre-existing discontinuities and inner damage in the form of the enucleation of shear bands that originate internal secondary failure surfaces and/or damaged rock mass zones. The stress–strain modeling predicts intense slope deformations in zones where rock mass damage actually occurred. This paper emphasizes the decisive connection between the geomechanical field survey and numerical modeling. The comparison of surface geological data acquired on the field with the mechanical indicators obtained from the numerical analyses can significantly improve knowledge of the rock mass damage process that involves unstable slopes approaching failure condition.

Geomechanical Field Survey to Identify an Unstable Rock Slope: The Passo della Morte Case History (NE Italy)

In this work, a geomechanical study performed on a natural rock slope located in north-eastern Italy (Tagliamento River valley, Friuli Venezia Giulia Region) is presented. The detailed geomechanical survey has provided a large bulk of field data proving that the investigated limestone slope is characterized by strong rock mass damage, thus resulting in a critical stability condition. Field evidence includes: (1) local faults crossing the rock mass and representing internal sliding surfaces; (2) slickensides and fault slips within the rock mass; (3) fracture joints of gravity-induced origin; (4) strong rock mass damage in over-stressed zones of the slope; and (5) slope monitoring data recorded by some installed devices. Three failure scenarios have been identified: a wedge failure involving a limestone block of 110,000 m3 (failure scenario 1: BLOCK1); a larger wedge failure involving an assembled limestone block of 200,000 m3 (failure scenario 2: BLOCK1-2-3); and a retrogressive failure involving a rear dolomitic block possibly triggered by the collapse of the limestone slope, mobilizing a maximum volume of 335,000 m3 (failure scenario 3: DOLOMITIC BLOCK). This paper shows that to comprehensively study stability problems involving natural rock slopes we must consider the interaction between pre-existing discontinuities, internal sub-blocks subdividing the unstable slope, rock mass strength and gravity-induced fractures that form during the delicate phase preceding slope collapse. Gravity-induced joints can be differentiated on the field from those of tectonic origin on the basis of some geometrical features, in particular their lower persistence and higher joint roughness.

Stability analysis of cut slopes using empirical, kinematical, numerical and limit equilibrium methods: case of old Jeddah–Mecca road (Saudi Arabia)

The stability of natural and man-made rock slopes has always been of great concern for engineering geology studies. To ensure a safe and functional design of excavated slopes, the first and most crucial step is to use reliable input parameters while searching for possible failure modes at the preliminary design stage. It is highly important for practicing engineers to determine the best material property for a chosen failure criterion. This study aims to analyze the stability condition of a case road cut from different aspects. For this purpose, two well-known failure criteria proposed for rock masses and rock joints were applied in the study depending on the scale of the problem in the slope face. The Hoek–Brown failure criterion was used to obtain input data required for modeling intact rock and rock mass behavior, and the Barton-Bandis shear strength criterion to determine the input data necessary for the modeling of rock joint behavior. SMRTool and Dips 7.0 programs were utilized to analyze the structurally controlled instabilities due to discontinuities in the cut slope. Slide 2018 and RS2 9.0 programs were executed to examine the stability condition of cut slope subjected to circular and non-circular failures, respectively. According to the results of numerical and limit equilibrium methods, no stability problem occurred in the case of slope due to non-sliding circular or non-circular slip failures. However, according to the results of empirical and kinematical analyses, some structurally controlled sliding failure modes of planar, wedge, and toppling were expected on the slope face. The result of this study clearly shows that to reach a final decision, different analysis methods should be used to evaluate the stability of cut slopes by considering various conditions of jointed rock masses.

Perspectives on the prediction of catastrophic slope failures from satellite InSAR

We demonstrate the potential of satellite Interferometric Synthetic Aperture Radar (InSAR) to identify precursors to catastrophic slope failures. To date, early-warning has mostly relied on the availability of detailed, high-frequency data from sensors installed in situ. The same purpose could not be chased through spaceborne monitoring applications, as these could not yield information acquired in sufficiently systematic fashion. Here we present three sets of Sentinel-1 constellation images processed by means of multi-interferometric analysis. We detect clear trends of accelerating displacement prior to the catastrophic failure of three large slopes of very different nature: an open-pit mine slope, a natural rock slope in alpine terrain, and a tailings dam embankment. We determine that these events could have been located several days or weeks in advance. The results highlight that satellite InSAR may now be used to support decision making and enhance predictive ability for this type of hazard.

A multi-approach rockfall hazard assessment on a weathered granite natural rock slope

After a recent forest fire, a weathered granite rock slope located in the northwest of Spain may become increasingly susceptible to rockfalls. This study presents a multi-approach assessment of rockfall hazard, with some features deserving particular attention. First, the geomorphological context represented by a weathered rock mass with multiple dispersed blocks presenting various potential instability mechanisms. Secondly, the presence of a hillfort behind the slope and a small village at its toe, limiting the available solutions for rockfall protection. Finally, the combination of different remote sensing techniques (unmanned aircraft system topography and light detection and ranging) with a semi-automatic geostructural analysis has been successfully applied to obtain both a 3D point cloud of the wide area under study in addition to an estimation of mean block volume for rockfall simulations. Additionally, the design and implementation of a protective measure (rock dynamic barrier) have been addressed.

Application of a Probabilistic Method Based on Neutrosophic Number in Rock Slope Stability Assessment

The stability of natural rock slopes is influenced by a wide spectrum of factors, such as mechanical properties of bedrocks and spatial distribution of discontinuities. Their specific values are typically incomplete, due mainly to the lack of effective and comprehensive methods to accurately characterize these factors, especially those inside of the slopes. The neutrosophic number is a useful tool to solve problems in indeterminate environment. This study introduces the neutrosophic theory into slope stability assessment. A vector similarity measure developed under neutrosophic environment was employed to establish a stability assessment method considering multilevel attributes of slopes. Using this method, the level of stability for studied slopes, i.e., stable, mostly stable, less stable, and instable, was determined by computing the relation indices. The method was applied to a group of rock slopes located in Zhejiang province, China, and the calculated results were compared with the reality of in situ survey. The field application showed that the developed method has a good efficiency and precision in assessing the stability of rock slopes. The obtained weight vector can reveal the key influential parameters that inherently control the stability of rock slopes.

New stability calculation method for rock slopes subject to flexural toppling failure

Flexural toppling is one of the main failure modes of natural and manmade anti-dip layered rock slopes. Based on cantilever slab tensile theory, the failure mechanism of flexural toppling was analyzed. A toppling slope is divided into three parts: the stability, tensile and shear zones. By considering this failure mechanism, a new stability analysis method for slopes against flexural toppling failure is proposed using equilibrium theory. In addition, a sensitivity analysis is performed to investigate the locations of possible failure surfaces and zones as well as changes in the stability of anti-dip rock slopes under different conditions. The results show that the positions of the inter-column forces have almost no effect on the stability factor but affect the areas of the tensile zone and the shear zone. The angle of the most dangerous potential failure surface increases with increasing dip angle and slope height, whereas the stability factor is negatively correlated with the dip angle and slope height but is positively correlated with the layer thickness. The failure mode is essentially flexural toppling when the layer thickness is small, but the failure mode gradually transitions to shear-sliding with increasing layer thickness. Finally, a real case study is analyzed using this method, and the calculated results are consistent with the actual conditions.

Combination of discontinuity characteristics and GIS for regional assessment of natural rock slopes in a mountainous area (NE Turkey)

Geographical Information Systems (GIS) have a very large spectrum of users. As in many engineering applications, GIS are frequently used in geotechnical projects, especially in producing various thematic and zoning maps such as various susceptibility and hazard maps. Instability maps for large areas with similar characteristic can be produced in a practical way by evaluating the results obtained by the data collected from field and laboratory studies.In order to introduce a methodology for producing rock slope instability maps for a large area, discontinuity controlled slope failures in the Köse Granitoid Complex (NE Turkey) were selected. To determine the types of failure such as planar, wedge, and toppling, and possible instable slope orientations kinematic analyses were carried out in the limited areas. The relationships between orientations of natural slopes and discontinuities obtained from kinematic analyses were evaluated with GIS software. Finally, discontinuity controlled instability maps were produced for the study area.Resulting maps show that the most common type of failure is wedge type. Additionally, the distributions of unstable areas along road networks were determined. Various land use types such as agriculture, grassland, settlement, and forest were also classified in order to predict the possible effects of slope instabilities. The methodology introduced in this study indicates highly promising results for the assessment of rock slope instability in large areas.

Improvements to field and remote sensing methods for mapping discontinuity persistence and intact rock bridges in rock slopes

Discontinuity persistence and intact rock bridges are critical factors that influence the stability of rock slopes. Persistence influences the extent of pre-existing potential failure surfaces, and intact rock bridges can add cohesion and tensile strength to an incipient failure surface, which must be destroyed before slope failure can occur. Despite continued research and improvements in mapping technology, computing power, and numerical modelling codes, there is no standard recommended methodology for field characterisation of intact rock bridges, or their incorporation into stability analysis. We use observations from remote sensing and field mapping investigations at three open pit mines and one natural rock slope to recommend improvements to field and remote sensing methods for mapping discontinuity persistence and intact rock bridges in rock slopes.We apply a fracture network engineering approach to discontinuity trace mapping, using new intensity factors to describe intact rock bridge trace intensity R21, and blast-induced fracture intensity B21. We emphasize the importance of multi-scale characterisation of discontinuity persistence and rock bridges in rock slopes, and we distinguish between different classes of intact rock bridges based on scale and geometry, with particular attention given to the distinction between laboratory sample scale intact rock bridges on incipient discontinuities, and larger rock mass bridges, which represent metre or larger scale intervals of fractured rock mass that may exist between very high persistence joints and faults.

Assessment of rock slope stability using GIS-based probabilistic kinematic analysis

Instability in a rock slope is highly dependent on unfavorable orientations of the discontinuities in the rock mass. Therefore, kinematic analysis has been used to analyze the structural condition of unfavorably oriented discontinuities using the stereographic projection method. In this analysis, the orientation of a discontinuity is compared with the slope orientation and friction angle by plotting the orientation of a discontinuity onto a stereonet. This stereonet-based kinematic analysis assumes that a uniform slope orientation and a tightly clustered orientation of the discontinuities exist. However, the slope orientation, represented by the slope aspect and slope angle, cannot be uniform if the slope faces are rugged, as in many natural rock slopes, or if the slope was created by deficient blasting. Moreover, the orientation of discontinuities measured in the field is often scattered, even in a same discontinuity set. However, such variations cannot be included in traditional kinematic analysis and representative values of the slope orientation and mean orientation of a discontinuity are used, which creates uncertainties. To overcome these problems, a GIS-based methodology using grid-based data on the slope orientation data and a probabilistic approach is proposed. To take into account variations in the slope orientation, a digital elevation model (DEM) of the slope face was used and the topographic data of the slope face was derived from the DEM. The slope faces were divided into 2×2m2pixels, and the orientation of the slope face was evaluated based on the grid cells. In addition, the orientation of a discontinuity was treated as a random variable, thereby accounting for natural variability, and a probabilistic analysis approach was adopted to deal with uncertainties and variability. Therefore, a grid-based probabilistic analysis module for the kinematic analysis was developed and used on a cell-by-cell basis to predict instability in spatially distributed slope faces. This probabilistic kinematic analysis was performed in a GIS environment because GIS provides an excellent platform for management and manipulation of raster-based spatial data. We applied this approach to the spatially distributed steep rock slopes in the Baehuryeong area, Korea, located along a tortuous mountain road.