Abstract We examine the stability of an ancient slope located at Jietai Temple in western Beijing of China, by using the remote monitoring system of sliding force combined with the combined finite-discrete element method (FDEM) as well as the field surveys. Potential pre-existing joints in the slope were firstly determined by the in situ study and rock mass mechanical properties were then estimated to be taken as input parameters in the numerical modelling, for understanding the instability mechanism of the slope. Results from this synthetic assessment together with the monitoring data suggest that current protection measures in the slope may not be sufficient so that the local authorities should define hazard zones and work out further development plans for the Jietai temple. 1. Introduction Limit equilibrium method and numerical modelling techniques are the most commonly used methods in the evaluation of slope stability. To complex rock and soil slopes, numerical approaches such as finite element and finite difference methods may be more suitable due to their flexibility when applied to simulate in situ stresses, loading condition, and multi-field interactions. Even though numerical modelling of rock slopes is commonly implemented by continuum approaches [1–4], features such as fracture, fragmentation, and crack propagation within rock mass extended to a computer code is very much appreciated to better describe the unstable process characteristics of rock slopes. The underlying geological data including fault, joint, foliated structure, and underground water table are required to be as the input parameters in the model to determine and calibrate the mechanical properties of rock masses in the numerical modelling of rock slopes. These in situ data together with monitoring information can further help to improve numerical modelling for providing the more reasonable prediction of the failure behaviours of rock slopes [5–7]. In the present report, we examine the stability of an ancient slope located at Jietai temple in western Beijing of China (Fig. 1) by using the field investigation, the monitoring technologies, and the combined finite-discrete element method (FDEM) [8]. Our work aims to help local authorities to define potential hazard zones of the region where Jietai temple locates and develop available plans for the reinforcement and early warning systems of the slope stability.

Abstract Many design codes recommend using the limit states design in different geotechnical design applications including rock slope stability. The Generalized Hoek-Brown (GHB) failure criterion is widely adopted for rock characterization. However, a partial factor is defined for the uniaxial compressive strength only in international codes like the Eurocode. The limit states slope stability using the reduced uniaxial compressive strength does not provide the same factor of safety when the reduced equivalent Mohr-Coulomb (MC) parameters are utilized in the analysis. This study aims at developing a partial factor for the Geological Strength Index such that the limit states design of weak rock slopes using the reduced GHB parameters becomes equivalent to the design using the reduced MC parameters. A parametric study has been carried out using the Limit Equilibrium Analysis approach for weak rock slopes considering several parameters such as the uniaxial compressive strength, the geological strength index, slope inclination and height, and water depth. It is concluded that the proposed partial factor should range from 1.10 to 1.15 according to the values of the uniaxial compressive strength and geological strength index. These two parameters are the most influential on the proposed partial factor. 1. Introduction Hoek-Brown (HB) criterion has been utilized for over three decades to characterize the failure envelope of rock mass [1]. It has gained a lot of attention from rock mechanics researchers and practitioners due to its ability to quantify the effect of discontinuities on the rock mass strength, especially weak rocks [2]. Hoek et al. [3, 4, 5] defined the rock mass strength by two main parameters, the Uniaxial Compressive Strength (σ ci ) and the Geological Strength Index (GSI). Limit equilibrium analyses (LEA) of rock slopes have been carried out for a long time using equivalent Mohr- Coulomb (MC) parameters (cohesion "c" and friction angle "Φ"). The equivalent MC parameters are determined by linear interpolation of the inherently-nonlinear GHB failure envelope in the same expected range of confining stresses. With the recent advances in the geotechnical software applications, it became now possible to carry out the LEA utilizing GHB parameters.

Abstract Two dimensional plain strain distinct element method has been used to analyze a curved slope under static and dynamic loading condition. Most vulnerable cross profile of the slope has been selected through kinematic analysis and slope mass rating specially devised for curved rock slopes. Static loading has been induced in the model to simulate conditions of the prevailing rock mass. Again dynamic loading has been performed according to the expected peak ground acceleration in the area in order to simulate the slope mass condition during earthquake. According to kinematic result and slope mass rating, the slope is more vulnerable towards 70° face direction. Static analysis results an unstable portion at the base of the slope. The whole slope is unstable under dynamic loading and is expected to threat the region with the risk of rock fall as well as failure of slope. 1. Introduction Failures in rock slopes are controlled by both rock material and discontinuities. In highly jointed rock mass with weak rock material, failure surface cuts through intact rock but in rock masses, with less number of joints and strong rock material, failure is controlled mainly by joint planes [1]. With the presence of joints, rock mass responses better to dynamic and static loading [2]. There are many numerical codes available to simulate dynamic loading in both continuous and jointed rock mass. Among them continuum method is well-known among geotechnical fraternity [3–5]. But despite of its astounding capability to handle any complex problem with ease and without any previous assumptions, this method lacks its compatibility in representing discontinuous medium [6]. A discontinuous medium is defined as an assemblage of discrete blocks separated by interfaces. Though continuum methods use special techniques (e.g. joint elements in FEM), they are only applicable for less jointed rock mass where little displacement is expected [7, 8]. To deal with inherent discontinuities in the rock mass and possible rupture in the intact rock, discontinuum methods prove to be best till date. Discontinuum methods are based on dividing rigid and/or deformable blocks by deformable interfaces. Among other discontinuum methods, distinct element method has an advantage of adopting both rigid and deformable blocks along with deformable contacts [9]. This method being explicit, directly solves the equations of motion by time marching scheme [10].

Abstract Discontinuities play a key role in the mechanical, hydraulic and deformational behaviour of rock masses, frequently having a considerable influence on the stability of rock slopes. They can be characterized by several geometric parameters as the orientation, persistence, spacing, etc. Although orientation has been traditionally measured through well-known techniques as a compass, more recent remote sensing techniques such as 3D laser scanning allow deriving both strike and dip direction of discontinuities. The novel SfM (Structure from Motion) technique, which is much less expensive than 3D laser scanning, is becoming mainstream within the research community. This paper examines the generation of 3D point clouds of a rock slope obtained from both, 3D laser scanning and SfM techniques, and their application to the extraction of the orientations of the main discontinuity sets. To this aim, a selected sector from a cretaceous sedimentary rock cut slope placed in Alicante (Spain) is analyzed using both photogrammetric and terrestrial laser scanner (TLS) point clouds. Using ground control points extracted from printed targets scanned by means of TLS provided very accurate coordinates. As a result of this, the obtained adjustment error was minor than 3 mm. The comparison of the resulting point clouds shows a good correlation when the surface is orthogonal to the line of sight. On the contrary, the SfM dataset showed inaccuracies on sub-horizontal and oblique surfaces. Finally, a geometrical analysis was performed by means of DSE software. Three discontinuity sets were extracted from both point clouds. However, one more was extracted from the TLS dataset, but not from the SfM dataset. 1. Introduction Characterization of rock masses requires the acquisition of information, which has traditionally been collected by means of fieldwork, using a compass and a tape. Collection of data by means of fieldwork is a time consumption process, and the data quality may be affected by the user's experience [1]. Currently, different remote sensing techniques, such as 3D laser scanning or Structure from Motion (SfM) are being developed and becoming mainstream [2]. These techniques allow the acquisition of millions of points of a surface with high accuracy, and thus, the surface of a rock slope is digitalized by means of this dataset. As this dataset represents the surface of the slope, it may allow the identification and extraction of the existing discontinuity sets, its orientations [3–8], the normal spacing [9, 10], the persistence [11, 12] and the roughness [13], if the point cloud has enough quality.

ABSTRACT: As open pit slopes continue to increase in depth, new approaches to characterising rock slope masses and slope failure mechanisms are required; these approaches should integrate and optimize new developments in remote sensing and geomechanical modelling. The author presents the state of the art in open pit remote sensing and numerical modelling and describes successful applications toward selected problems and case studies. 1 INTRODUCTION 1.1 Background Practical research on open pit slope design and slope performance has seen major advances during the last decade in large part driven by the Large Open Pit, LOP, project which involved 12 sponsoring mining companies. The LOP project has to date led to two major guideline publications one relating to open pit slope design Read & Stacey (2009) and the other groundwater, Beale & Read (2013). Two additional publications will soon address open pit slope design in weak rock masses and waste dump and stockpile design. Since 2006 there have been five international slope stability conferences with a major focus on open pit slope stability. The last 10 years has seen important advances in remote sensing and numerical modelling applied to open pit slopes; ongoing research is capitalising on this work with continued improvements in hardware and software. Figure 1 shows a Venn diagram illustrating the suggested integrated use of numerical modelling, slope characterisation and slope monitoring in order to increase our understanding of pit slope deformation mechanisms. 2 REMOTE SENSING APPLIED TO PIT SLOPES 2.1 Pit slope characterization Five methods of remote sensing will be described and their application to pit slope characterization. The large open pit guidelines provide a suggested outline for pit slope design, Figure 2, Read & Stacey (2009). Remote sensing techniques can be used to considerable advantage to supplement conventional engineering geological mapping providing data on the geology, structure, rock mass and hydrogeology allowing the development of improved geotechnical models.

ABSTRACT: With increase of design seismic intensity, analytical methods and modeling for evaluating deformation and failure of rock slopes during earthquakes appropriately are needed. In this study, shaking table model tests of rock slopes with a sliding plane inclined at angle of 15 degrees were conducted and the dynamic response of sliding block was observed using laser displacement sensors and accelerometers. To simulate the block interaction such as sliding or separation, the numerical simulations are conducted by the dynamic limit equilibrium method and the finite element model, the applicability of analytical methods is verified. 1 INTRODUCTION Dynamic response analysis is conducted to evaluate the stability of slopes under seismic conditions at important structures such as main traffic routes, nuclear power plants etc. Stability analyses are commonly carried out through numerical analysis assuming that rock mass is elastic and homogeneous on the basis of the results from PS logging and/or the seismic coefficient method. However, the behavior of rock masses is greatly influenced by the geometrical distribution of discontinuities within the rock mass. It's necessary to figure out dynamic behavior and fracture morphology of discontinuous rock slope. With increase of design seismic intensity, analytical methods and modeling for evaluating deformation and collapse of rock slope under earthquake appropriately are expected. In this study, shaking table tests on rock slopes with a sliding plane inclined at an angle of 15 degrees were conducted and the dynamic response of sliding block was measured using laser displacement sensors and accelerometers. To simulate the block interaction such as sliding or separation, the numerical simulations are conducted by the dynamic limit equilibrium method and the finite element model, the applicability of analytical methods is verified. 2 MODEL EXPERIMENTS ON SEISMIC STABILITY OF DISCONTINUOUS ROCK SLOPE 2.1 Outline of experiment In order to understand the dynamic response and stability of rock slopes, several shaking table tests on rock slopes with a potentially unstable block on a dipping plane shown in Figure 1 were carried out. The assumed rock slope with a height of 50 m and having a potential plane at an angle of 5 degrees is scaled down to a model with a scale of 1/500. The model material is sandy Ryukyu limestone and locally is knows as Awa-ishi. The input-wave, the acceleration of upper block acceleration and relative displacement of the potentially unstable blocks were measured using accelerometers and laser displacement transducers as shown in Figure 1. Table 1 gives the specifications of the shaking table and monitoring devices.

ABSTRACT: Discontinuities play a crucial role in the stability of any engineering structures such as open pit slope, highway wall, etc. Because the discontinuities are mechanically weak zones and failures occurred thought discontinuity surfaces and intersection lines which are bounded rock blocks. Therefore, the characterization of rock mass and the stability analysis based on this evaluation requires a deep understanding of the discontinuity geometry (i.e. Dip and dip direction). In order to assess the global quality of a rock mass, several authors proposed the use of geotechnical classifications for a long time. All of the classifications are including several geometric parameters in several degrees. Intersection lines between discontinuity surfaces and points of them on the visible surfaces of any engineering structure that excavated rock mass may also be indicators of any instability. This paper describes a new approach to modeling of intersecting lines and points as the evaluation of the instabilities of an engineering structure which excavated in rock masses. This study includes a series of derived linear equations to describe the orientation of intersecting lines, the location of exposed intersection points and finally statistical distributions of the obtained results. Kernel Densities Estimation (KDE) was used as a tool for the statistical analysis. This analysis carried out as the contouring intersection points by selecting critical intersection lines according to friction angle of discontinuity surfaces. The model seems to be a practical tool for assessing of rock mass instabilities. To run the model, dip, dip direction and spacing values are adequate. 1 INTRODUCTION Visually explaining failure mechanisms is important in decision-making and design processes. A systematic and well-designed visual study provides the most effective way toward finding solutions to many of the problems that managers and engineers face. For this particular work, the most important components to be examined are discontinuities in the rock mass (faults, joints, beddings, etc.). Discontinuity, inhomogeneous and anisotropic nature of the rock mass is mainly attributed to its interior behaviours. When dealing with discontinuous rock masses, the properties of the discontinuities of the rock become of prime importance, since they will determine the mechanical behaviour of rock masses (Bieniawiaski 1989).

ABSTRACT: The Zapotillo Dam is a 130m high roller compacted concrete dam constructed in Mexico. In connection with the excavation of a recent slide at the left abutment of the dam, a slide of the adjacent slope was activated. The lower part of the sliding surface is located at the elevation of the dam's crest. The article describes the measured sliding movements, the inmediate stabilizing measures, the FE back-analyses as well as the long-term support and measurement results during and after stabilization of the slope. At the right abutment above the stilling basin, there is a rock slope which tends to toppling failure as well as a large deposit of talus material. The article reports on the FE stability analyses as well as the excavation and stabilization measures foreseen in the design. 1 PROJECT The Zapotillo dam is currently constructed in the area of the major city Guadalajara, Jalisco, Mexico (Fig. 1). It is planned to be a 130 m high roller compacted concrete dam, which will create a drinking water reservoir with a volume of aprox. 1 billion m 3 . In plan view, the dam has a curved geometry with a crown length of around 390 m and a centric spillway (Fig. 2). The dam is designed as a gravity dam. The sliding slope, which will be dealt with in chapter 3 of the given publication, is located at the left abutment of the dam (see red circle in fig. 2). The toppling zone and debris of talus material, which are discussed in chapter 4, are located at the right hand side of the stilling basin (see red circle in Fig. 2). 2 GEOLOGICAL AND GEOTECHNICAL CONDITIONS At the dam site an alternating sequence of volcanic rocks, mainly tuffs and ignimbrites, is encountered (Fig. 3). The ignimbrites are strongly jointed and tend to form rock columns (Fig. 4). Uniaxial compressive strength amounts to aprox. 10 to 50 MN/m 2 . With values in the order of 2,000 to 5,000 MN/m 2 , they have a rather small deformability modulus. The Tuff layers have an even smaller deformability modulus, which ranges in the order of magnitude of 500–3,000 MN/m 2 . Their uniaxial compressive strength ranges between 2 and 15 MN/m 2 . They are also jointed (Fig. 5).

Abstract Rockfalls are very common along the Himalayan roadways because of the highly jointed nature of rock mass. Discontinuities in the rock mass render them extremely anisotropic, reduces the strength and create avenues for different failure mechanisms like planar, wedge and toppling in destabilizing the slopes. The formation of overhangs due to excavation, coupled with the high density of joints make them a highly susceptible zone for the initiation of rockfall activity. The present study area is a part of seismically active Himalayas (Luhri, Himachal Pradesh), where the occurrence of mild to major tremors are quite rampant. Thus, the study concentrates on the possibility of initiation of rockfall activities due to seismic activities using distinct element modelling (DEM) approach. The results shows contrasting difference in the magnitudes between displacement and velocity in static as well as in dynamic case, causing rockfall to initiate in the latter case. 1 Introduction Rockfall is a major concern along transportation corridors in hilly areas, usually prevalent in the jointed rock slopes (Ferlisi et al. 2012 and Budetta 2004). It is a two-stage phenomenon where initial stage is the detachment of blocks while the second stage relates to the motion of the falling body, post failure. The main triggering factors for the detachment of blocks are erosion and weathering along the structural discontinuities, rainfall, earthquakes and others (Dorren 2003, Singh et al. 2010, Asteriou et al. 2012). Studies have shown a good correlation between the landslides density and the areas of strongest ground motion, while their frequency declines on moving away from the epicenter (Meunier et al. 2007). Sepulveda et al. (2005) studied the rock slope failure due to topographic amplification of strong ground motion in case of Pacoima Canyon, California and observed that the most frequent failure was planar and wedge type derived from rockfalls in many cases. The dominant mode of failure can be established from the relationship between the orientation of structural discontinuities and surface topography at any particular site, but the analysis of mechanism behind the initiation of rockfall due to seismic shaking requires the application of rigorous numerical models that have the capability to model large strain of a discontinuous media. Seismically induced rockfall occurs as a combined effect of gravity and seismic acceleration producing short-lived stress, which exceeds the cohesive and frictional strength of the earth materials (Newmark 1965). As a result, slope failure can take place due to slight disturbance in slopes that may have been stable under static loading time. Earthquakes produce two types of ground accelerations. Out of the vertical and horizontal accelerations, the later one is known to cause greater impact on slopes (Romeo 2000). Past studies have shown that even an earthquake of magnitude 4.0 can trigger a rockfall activity (Keefer 1984). The threshold displacement responsible for causing landslides ranges from 2–5 cm (Wilson & Keefer 1985).

Abstract Numerical calculation methods for landslide hazard assessment are typically applied on small areas. However, based on simple geotechnical models, the application is also useful for large areas. The utilization of grid-based geometrical and geological data in combination with geotechnical parameters allows calculating of well-known safety factors for slope failure in rock and soil. Furthermore, the effect of water availability on slope stability can also be taken into account and is useful to estimate the effect of long-term precipitation events on slope stability. The calculated safety factors can be represented on a map by means of geoinformation systems (GIS). This paper gives an overview of the applied calculation methods as well as GIS-supported visualization of the calculation results. 1 Introduction The assessment of landslide hazard is an important topic in earth sciences for many decades. Due to urbanization on sloping areas and an intensification of heavy precipitation events, a higher occurrence of slope instability and landsliding is reported. A significant body of qualitative and quantitative methods for the assessment of landslide hazard is available (Aleotti & Chowdhury 1999). The major disadvantage when using qualitative methods is the problem of subjectivity and makes it difficult to compare landslide hazard maps by different experts. The use of quantitative methods, like the application of geotechnical models, based on widely used mathematical methods and is quite comprehensible. The index of stability is the well-known safety factor. The calculation can be fully automated and enables a quick slope stability assessment for large areas. By varying the input parameters, it is easy to calculate a range of possible safety factors. Such methods are typically applied only on small areas because they require many geometrical and geotechnical parameters. However, it is possible and in our opinion useful, to make an estimation of landslide hazard for large areas based on simple geotechnical models.

Abstract The highway Durres- Prishtina is very important for Albania and Kosovo, because this highway connect Albania with Kosovo and Europe countries. In this paper would like to present our study about unstable rock slopes, where will evidence the geological and geodynamic phenomena's which can happened in above mentioned zones. Also want present the hydrological and geotechnical studies, kind of discontinuities and fissures, the mechanical and physical characteristics of the rock etc. 1. Introduction Albania is mountainous country (2/3 of their territory are mountains and hills). One of very dangerous phenomena's, which every year brings considerable damages (in individual's and country's economy) is the sliding phenomena's. Especially in road's infrastructure sliding phenomena's are frequent, dangerous and accompanied with big expenses to secure normal functioning of roads and their security. In last year's, in Albania, many roads, bridges and tunnels are constructed. The roads system has made possible connection of Albania with their neighbor countries and other away countries. One of this artery is highway "Rruga e Kombit", which made possible connection between Albania and Kosovo. Also this highway makes possible connection (through Albania territory) of 8 European corridor (east-west, which connect Europe with Asia) by 10 European corridor (north-south, which connect Central Europe with Greece). The highway Durres-Prishtina passes through fields (segment Durres- Milot), through mountains (segment Milot- Morina) and through fields and hills territories (segment Morina- Prishtina). In the second segment a part of the highway passes along the deep valley of Fan's river and in some zones near unstable rock slopes (fig. 2). Our study, presented in this paper, consist in: determination of the geological and geodynamic phenomena's in these zones, particular geological and hydrological investigation, study of the kind of the fractures, determination of the physical and mechanical rock's characteristics, mapping of the unstable rock zones, calculation of the safety factor for the rock slopes and recommendation of the engineering measures to secure slope stability. Finally we have taken some conclusions which can be serve and for the other similar cases.

Abstract With the introduction of Eurocode 7 the design of rock slopes in theUKare commonly undertaken in accordance with Design Approach 1 combination 2. This paper presents two rock slopes in different strata, one in hard rock (UCS>50MPa) the second in soft sedimentary rock (UCS<25MPa), which were analyzed and designed using the numerical modeling software UDEC. The required level of support using pattern bolts and mesh for each rock slope is compared between a Eurocode 7 Design Approach 1 Combination 1 and 2 against a design using a global factor of safety approach. The paper concludes with a comparison of the costs of the implementation of each of the design approaches 1. Introduction In 2010, EN 1997–1:2004 Eurocode 7 (EC7) replaced the national design codes within the European Economic Community, becoming the mandatory code used by designers for geotechnical design. Before the introduction of EC7 many designers used moderately conservative parameter values and required a Factor of Safety (FoS) in excess of 1.3 for permanent structures. The main change for geotechnical design with EC7 is the introduction of partial factors on rock strength, loading and resistance, and a global stability ratio (GSR) of 1 (unity) is required. There are three different methods given in EC7; Design Approach 1 (DA-1), Design Approach 2 (DA- 2) and Design Approach 3 (DA-3). In the UK DA-1 has been adopted. In principle, DA-1 requires two separate calculations to be performed in which the rock strength, loading and resistance are examined using two different combinations of sets of partial factors. In DA-1 Combination 1 (C1) partial factors are applied to resistances and actions. In Combination 2 (C2) partial factors are applied to the strength of the rock. EC7 covers many geotechnical design cases but not all of them. In particular the code does not cover passive anchorages in rock (rock dowels). Typically, rock dowels are preferred by geotechnical contractors for projects which involve a large installation of large numbers of anchorages (e.g. excavations) and costs can be minimized and construction programmes shortened by avoiding stressing operations. In the UK design of rock dowels is covered partially by British Standard 8006–2:2011 The Code of Practice for Strengthened/Reinforced Soils Part 2 – Soil Nailing. This standard is "intended to harmonize the design approach of soil nailing with other geotechnical structures designed using BS EN 1997–1:2004" This standard includes a list of partial factors to be used in the design of passive anchorages (Table 1). However, the standard states that "The factors provided in this standard have not been established for use in conjunction with numerical methods". Clearly the use of EC7 partial factors in numerical modelling requires further clarifications. This is what this papers intends to do, particularly in reinforced rock slope.

Abstract Monitoring in field performances of rock masses is required and widespread in engineering practice for both handmade structures (tunnels, cuttings, etc.) and natural sites (i.e. landslides). The presence of discontinuities and their role in displacement localization and hydrogeological anisotropy of rock mass are the key elements in order to define an appropriate monitoring program. The application of new nanotechnologies in the geotechnical and rock mechanic fields has increased the amount of acquired information both in space and frequency. Along with the awaited introduction in the EC7 of specific considerations regarding geostructural characterization and failure criteria definition, it is desirable to propose specifications regarding field instrumentation monitoring devices and data analysis. A review of the rock mass key physical properties that should/can be monitored in field, according to specific projects or aims, is presented, along with the state of the art of suitable field monitoring equipment. 1. Introduction Monitoring can be regarded as the regular observation and recording of events taking place in a certain structure. Displacements, deformations, water pressure, natural and induced stresses are among the most commonly recorded entities during monitoring. In particular, deformation monitoring is the systematic measurement and tracking of alterations in the shape (position and altitude) of an object, resulting from the application of external forces. Deformation monitoring and gathering of measured values are major elements for further computation of soil and rock stability, deformation analysis, prediction and alarming (Moore, 1992). Since each monitoring project has specific requirements, the applied measuring device depends on the application features, the chosen measurement method and the required regularity and accuracy. Therefore, monitoring of slopes or landslide areas can only be defined, designed and realized using an interdisciplinary approach (Wunderlich, 2006). A close cooperation among experts from geology, geophysics, hydrology, geotechnics together with experts from any measurement discipline such as geodesy, remote sensing and other academic fields, is an indispensable requirement. A series of disturbances can affect the pre-existing natural state of stress of a rock or soil slope.

Abstract A probabilistic analysis is applied to rock slope stability with an example case of a rock slope with translational potential failure mode. The capacity and the demand are represented as independent triangular random variables. The distribution of the factor of safety is found analytically and its reliability measures are evaluated, allowing for decisions to be taken in terms of risk and reliability. The same slope is examined in its limit state by applying the partial factors approach of Eurocode 7. The Eurocode design is compared to the traditional factor of safety and probability of failure. 1. Introduction Numerous uncertainties, arising from natural variability in space and time, experimental errors, imprecise information, insufficient knowledge, up-scaling, simplistic assumptions, etc., are pervasive in rock engineering. These are commonly taken into account, indirectly, in the traditional factor of safety design, where acceptable safety factors are selected through experience or regulation, depending on application and its importance (e.g. Priest & Brown 1983). Some drawbacks may be recognized in this approach (Yucemen et al. 1973). The same value of the safety factor is adopted (or imposed) for a particular type of application, regardless of the degree of uncertainty involved (Duncan 2000), the risk level associated with it, or the amount and quality of information available before and acquired during construction. The type of uncertainty is also relevant to rock engineering (Bedi & Harrison 2013) and its assessment essential for reliable design (Bagheri & Stille 2011). Limit States Design (LSD) in Eurocode 7 (CEN 2004) introduced several changes to the previous geotechnical design practice. Verification at the ultimate limit state requires that the design actions, increased to reflect a low probability of occurrence, be lower than the design resistances, which have been factored down to reflect prescribed (or intended) probabilities of being exceeded. The values of the partial factors of the characteristic actions and material parameters are largely associated to variability and other uncertainties and therefore the partial factors approach may be considered as a form of reliability based design, although for complex systems the relation of the partial factors to the intended failure probabilities may be somewhat difficult to observe. Calibration of the partial factor design equations has been primarily based on method a of Figure 1, where the relation between the various calibration methods considered by EN 1900 (CEN, 2002) is presented. There, the probabilistic calibration procedures are divided into Level II reliability and Level III probabilistic methods.

Abstract Prediction of rock slope deformation behavior as well as its monitoring is significantly important for stability assessment. This study clarified the deformation modes due to excavation in the case of plateau type mine based on the 2-dimensional finite element analysis. The step-by-step deformations with successive excavations were investigated in detail for different slope angles and the results were presented considering the in-situ measurement of surface and interior displacements of rock mass. The results showed a clear dependency of deformation modes on Poisson's ratio of rock mass and slope angle, in which the direction of rock surface movement due to excavation became opposite. The insight obtained here can be useful to understand of the monitoring on rock slopes in plateau type mine. Introduction Displacement (and/or deformation) monitoring is one of the powerful tools for stability assessment of the rock slopes since apparent deformation has been always observed before final failure of it. In other words an increase in displacement is dangerous sign. However, rock slope can be elastically deformed due to excavation. It is clear that rock slope in an open pit mine is gradually deformed with the progress of mining (Kodama et al. 2009). Therefore, deformation mechanism is important for stability assessment of rock slope in an open pit mine. Numerical analysis is one of the effective methods for the interpretation of measurement results. Inelastic deformation in measurement results can be detected once elastic deformation due to excavation is cleared. In other words, the prediction of elastic deformation due to excavation is useful for early detection of unstable state of the rock slope. Kaneko & Kato (1997) assessed the stability of rock slope in an open pit mine by the field displacement measurement and elastic stress analysis. They found that the deformation behavior of rock slope is affected by not only slope angle but also initial rock stress. Kodama et al. (2009) carried out elastic analysis for an open pit mine in 3-dimension. They estimated Young's modulus of the ground by back analysis and predicted elastic deformation of a rock slope. In addition, Obara et al. (2000) reported that the measured horizontal deformations of an open pit mine due to floor excavation was in good agreement with those obtained by elastic analysis. However, open pit mines analyzed in these studies were classified into pit type, and the deformation due to excavation at the pit floor was just investigated. Slope deformation in other configurations such as plateau-type mine has not been cleared yet. Investigation of the other configurations of rock slope excavation such as plateau-type mine is also important.

Abstract In mountainous areas, tunnel portals and job sites for tunnel construction are often located in areas prone to rockfall events. Providing the safety of roads close to tunnel portals, subjected to rockfall risk, is an unavoidable issue that should be taken into account. In this paper, a risk management approach has been introduced to evaluate rockfall risk on the road stretch at the entrance and exit of tunnels. The event tree method is improved to achieve a flexible solution to calculate the rockfall risk for tunnels. Furthermore, some design abacuses are developed to provide the input parameters related to the event tree. Afterwards, a parametrical analysis is presented to explain the methodology. The elaborated approach can be useful to choose best technical solutions and design protection devices against rockfall. 1 Introduction The rock block collapse from slopes is one of the most frequent hazards for public transportation systems in mountainside areas. The effects of these instabilities can led to vehicle damages, injury or death of drivers and passengers as well as economic loss due to road closure (Duncan & Norman 1996). Referring to tunnelling engineering, sometimes tunnel portals and job sites for tunnel construction are located in areas prone to rockfalls and the rock block detachments can occur while the tunnel is in service or during construction. In order to deal with this issue, several geometry configurations of a rock slope prone to rockfall overhanging a tunnel portal have been defined and the results of trajectographic analysis have been analysed. The rockfall trajectographic analysis has been performed to evaluate the number of rock blocks that can reach the road and their percentage. This analysis has been done with a 2D method and a lumped mass model has been utilized. The geotechnical restitutional parameters (k n , k t , ϕ) are set as standard values available in technical literature (Giani 1992, Hungr & Evans 1988, Azzoni et al. 1995). The goal of this research is to provide a design procedure and suggest somemeasures to prevent the falling rock blocks toward the road such as rockfall barriers and/or artificial protruding tunnels (Fig. 1a,b,c).

Abstract Terrestrial laser scanning has propelled recent advancements in rock slope engineering. Building models with millions of points to discretize an actual slope has provided resolutions which empower computer based analysis/measurements of rock slopes as a supplement/substitute for conventional data acquisition. Herein, we are following-up such trends at a pilot site on the M-22 highroad near Ljig (Serbia). The site is composed of stratified Cretaceous flysch sediments, traversed by several joint sets, making a convenient setting for potential failures. Prior to the kinematic analysis, modeling of the 3D surface has been performed on 1 cm resolution point cloud, obtained by Leica Scan Station 2. The 3D surface model was then mapped for the planar discontinuities, forwarded to the kinematic analysis for planar, wedge and toppling failures. The analysis matches with previous findings, indicating that the most dominant failure type is a planar slide, showing that proposed methodology yields reliable and concurrent results. 1 Introduction Recent development in terrestrial laser scanning technology has resulted in advancements in numerous engineering branches, and rock slope engineering is one representative example. Collecting spatial information on millions of points, usually called point clouds has found its use in modeling of actual slopes and allowed high-resolution, computer-based analysis as a supplement/substitute for conventional field data acquisition (Tonon & Kottenstette 2006, Kemeny & Turner 2008). There are a number of benefits in using point clouds as discrete models of the rock slopes: – they enable more objective and more accurate measurements (of distances, areas, volumes) and mapping (of planar and linear structures) on accessible and inaccessible slope parts (high and steep rock faces) – high-precision cross-sections and contour lines, which are for instance required in stability analysis, can be obtained. – advanced visualization of slopes and objects on them. – the models (saved in digital form) are available for reuse at any time with no additional expenses, unlike the field investigation revisits – they provide a very good base for the monitoring of the particular slope sites, where each change can be accurately determined and interpreted or predicted. On the other hand, the drawbacks could be recognized in the following:

Abstract: For determining factor of safety (FOS) for rock slopes using numerical strength reduction technique with Hoek Brown parameters, two different approaches are generally used. Approach I (Global): Approximation of the non-linear failure envelope by a best-fit linearization and subsequent global c-φ -reduction by classical approach. Approach II (Local): Determination of local c and φ values according to the local stress state and subsequent local c-φ –reduction. Different numerical methods based on "Global" and "Local" approaches are tested for rock slopes with different configurations, in different rocks at their different physical conditions. Analysis for determining FOS using Limit Equilibrium Method with equivalent c-phi values of Hoek-Brown parameters (RocLab) was also carried out. As observed, global approach in comparison to the local approach can lead to a deviation of about ± 15 %, for rocks with GSI values up to 65. FOS values determined using Limit Equilibrium Method are mostly in higher (up to 10 %) side. If local approach is considered as more ‘correct’, depending on the parameters, results of the global approach can lie on the safe or unsafe site. Evaluation of slope stability using the global approach can result in uneconomic slope design or overestimation of safety margin. 1 INTRODUCTION For determination of safety factors, especially but not only for slopes, the numerical shear strength reduction technique, based on the Mohr-Coulomb constitutive law has became popular now a days, replacing the conventional limit equilibrium techniques. The Mohr-Coulomb constitutive law usually characterising the failure envelop for soils, is defined by a linear relation between shear- and normal stress and between minor and major principal stress, respectively. At present, some effort is being made for use of the classical shear strength reduc-tion approch based on the Mohr-Coulomb constitutive law towards the non-linear failure envelopes.

ABSTRACT: The determination of the geometrical features of failure modes is the first step in slope design and planning applications. In addition, it is well known that wedge rock blocks are the most common failure mode type. This paper presents the basic components of an approach for establishing the geometry of wedge rock blocks of fractured rocks. A simple new classification system was developed for the construction of the model. The main advantage of this new geometric model is that it presents more practical and rapid solutions for potential failure mechanisms than other classical solutions. The results obtained from an experimental field show the effectiveness of the proposed modeling method. 1 INTRODUCTION Discontinuity orientation is an important parameter affecting rock slope stability, as this feature mainly influences the failure types and kinematic instability. In rock slopes it is often assumed that failure is confined to preexisting fracture planes or combinations of planes. This assumption implies that there are various failure modes (Hadjigeorgiou & Grenon, 2005). Thewedge failure mode is a common type in jointed rock slopes. The stability of these exposed wedges is mainly influenced by the geometry of the wedges. Therefore, the detailed geometry of the possible sliding mass should be analyzed first. Several previous researchers focused on subjects regarding the stability problems of discontinuous rock slopes, such as the generation of blocky rock mass by Warburton (1983) and Heliot(1988); the determination of sliding modes and safety factors of sliding blocks by Hoek & Bray (1981); the assessment of kinematic feasibility, using stereographic projection by Priest (1980), and the block theory developed by Goodman&Shi, 1985. Hocking (1976) dividedwedge failures into two modes, in terms of sliding planes of wedges. One is single plane sliding (plane failure), and the other is double plane sliding.

ABSTRACT: As one of the last sections of the A9 Motorway through the Upper Rhone Valley, the by-pass around the city of Visp is currently under construction, comprising of two blast-and-drill tunnels of 2.7 km and 4.2 km respectively. The shorter tunnel is the more demanding one, as an existing old tunnel is to be incorporated into one of the two tubes while staying in use. This creates a delicate situation at the north portal in terms of construction sequence and slope stability. These factors are discussed in this paper. 1 PROJECT OVERVIEW 1.1 Traffic situation in the upper Rhone valley When completed in 2017, the Visp by-pass will link the Rhone Motorway A9 from Lake Geneva with the Simplon pass and alleviate the densely populated town of Visp from the commuting traffic to and from Brig (A9-VS). As the industrial area north of Visp makes it difficult to accommodate a 4-lane motorway, it was decided to place the by-pass south of the town in the mountains which mark the junction of the Saas valley with the Rhone valley (Fig. 1). 1.2 Altering an existing tunnel The two tunnels, the 2.7 km long tunnel Visp to the west and the 4.2 km long Eyholz tunnel to the east, are linked by a bridge crossing Staldbach creek. Tunnel Visp is the shorter one, but has to integrate an existing single-tube tunnel via an underground junction, which will stay in use during construction as access/exit tunnel into the Saas valley and accommodate the tourist traffic toward the well-known skiing resorts Zermatt and Saas Fe. Apart from the caverns necessary for the underground junction and the connecting tube over-passing the new motorway, an unusual design problem is posed by enlarging the existing Vispertal tunnel to become the south tube of the motorway.