Evaluation Of Rock Slope Stability Research Articles

Comprehensive Stability Evaluation of Rock Slope Using the Cloud Model-Based Approach

This article presents the cloud model-based approach for comprehensive stability evaluation of complicated rock slopes of hydroelectric stations in mountainous area. This approach is based on membership cloud models which can account for randomness and fuzziness in slope stability evaluation. The slope stability is affected by various factors and each of which is ranked into five grades. The ranking factors are sorted into four categories. The ranking system of slope stability is introduced and then the membership cloud models are applied to analyze each ranking factor for generating cloud memberships. Afterwards, the obtained cloud memberships are synthesized with the factor weights given by experts for comprehensive stability evaluation of rock slopes. The proposed approach is used for the stability evaluation of the left abutment slope in Jinping 1 Hydropower Station. It is shown that the cloud model-based strategy can well consider the effects of each ranking factor and therefore is feasible and reliable for comprehensive stability evaluation of rock slopes.

The Dynamic Evaluation of Rock Slope Stability Considering the Effects of Microseismic Damage

A state-of-the-art microseismic monitoring system has been implemented at the left bank slope of the Jinping first stage hydropower station since June 2009. The main objectives are to ensure slope safety under continuous excavation at the left slope, and, very recently, the safety of the concrete arch dam. The safety of the excavated slope is investigated through the development of fast and accurate real-time event location techniques aimed at assessing the evolution and migration of the seismic activity, as well as through the development of prediction capabilities for rock slope instability. Myriads of seismic events at the slope have been recorded by the microseismic monitoring system. Regions of damaged rock mass have been identified and delineated on the basis of the tempo-spatial distribution analysis of microseismic activity during the periods of excavation and consolidation grouting. However, how to effectively utilize the abundant microseismic data in order to quantify the stability of the slope remains a challenge. In this paper, a rock mass damage evolutional model based on microseismic data is proposed, combined with a 3D finite element method (FEM) model for feedback analysis of the left bank slope stability. The model elements with microseismic damage are interrogated and the deteriorated mechanical parameters determined accordingly. The relationship between microseismic activities induced by rock mass damage during slope instability, strength degradation, and dynamic instability of the slope are explored, and the slope stability is quantitatively evaluated. The results indicate that a constitutive relation considering microseismic damage is concordant with the simulation results and the influence of rock mass damage can be allowed for its feedback analysis of 3D slope stability. In addition, the safety coefficient of the rock slope considering microseismic damage is reduced by a value of 0.11, in comparison to the virgin rock slope model. Our results demonstrate that microseismic activity induced by construction disturbance only slightly affects the stability of the slope. The proposed feedback analysis technique provides a novel method for dynamically assessing rock slope stability and can be used to assess the slope stability of other similar rock slopes.

Rock slope stability evaluation in static and seismic conditions for left bank of Jinsha River Bridge along Lijiang-Xamgyi’nyilha railway, China

Jinsha River Bridge is located along the Lijiang-Xamgyi’nyilha railway on the southeastern Tibet plateau; it is an area with a high prevalence of earthquakes. The bridge abutments were designed to be constructed in river bank slopes, where rocks are controlled by two sets of joint planes that significantly influence the stability of the left bank slope. According to the engineering-geological conditions and the characteristics of discontinuities, strength properties of the rock mass were obtained based on Barton model and direct shear test. Numerical analyses were performed using FLAC3D software to examine the slope’s response to seismic loading. Then in order to evaluate the damage trends of the rock mass under the different loading conditions, a calculation model based on the geological parameters and slope stability was simulated and analyzed using the discrete element numerical simulation program UDEC (Universal Distinct Element Code), and the effect of degradation of discontinuities on the slope stability was investigated. The results show that the destruction of rock mass under the gravity, bridge foundation, and seismic load are mainly concentrated within 30 m depth of slope, and the slope under loading may slide along joint planes. In addition, the dynamic analysis by amplification of the input loading indicates that instability occurs to the bank slope at a height of about 200 m, and rock blocks will fail under seismic load. Therefore, to prevent the slope from deformation under the engineering loading and strong earthquakes, the bridge foundation should be strengthened.

Evaluation of rock slope stability for Yujian River dam site by kinematic and block theory analyses

Lithological information, rock mass fracture data and discontinuity shear strength obtained through field investigations have been used to conduct kinematic and block theory analyses for the rock slopes that exist in the dam site to evaluate the stability of the slopes. The analyses were performed using mean discontinuity set orientations for each rock mass region under gravitational loading to calculate the maximum safe slope angles (MSSA) for different cut slope directions. Results show that final MSSAs obtained from kinematic analysis are less than or equal to that obtained from block theory analysis. The following conclusions have been made based on the block theory analysis results, which are closer to the reality: (1) The final MSSA range between 30° and 47°, 44° and 70°, 47° and 69° for cut slope dip directions of 20–30°, 105–210°, and 270–355°, respectively; (2) For cut slope dip directions of 20–30°, 200–210° and 275–315°, wide ranges of values have been obtained for the final MSSA reflecting the influence of variability of fracture orientations on MSSA; (3) Apart from the region R-d-1 for slope dip directions in the range 20–30°, rest of the regions at the dam site seem to be stable for slope angles less than 40°. Detailed comparisons are given between the kinematic and block theory analyses covering both the theoretical concepts and application results. Also a brief comparison is included between the laboratory and in situ discontinuity shear strength results.

Development of a computer program for inhomogeneous modeling using 3-D BEM with analytical integration and its application to rock slope stability evaluation

Development of a computer program for inhomogeneous modeling using 3-D BEM with analytical integration and its application to rock slope stability evaluation

An application of the rock engineering systems (RES) methodology in rockfall hazard assessment on the Chengdu-Lhasa Highway, China

In the evaluation of rock slope stability, there are many kinds of uncertainties including the input parameters uncertainty, the calculations uncertainty, and the procedure. Slope stability analysis can be classified into deterministic analysis or probabilistic analysis depending on how uncertainty is incorporated and evaluated. Probabilistic method takes into consideration the inherent variability and uncertainties in the analysis parameter. In this study, rock slope stability analysis, especially probability analyzes will be reviewed. 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. The sliding plane of the landslides passed through the thick clay layer. The tension cracks developed behind and are parallel to these landslides scarps. Considering these information, it is thought that the new failure can develop in these slopes. For this, no technical entry was allowed for this part of the quarry area. Therefore, the probabilistic stability analysis of these new slopes was performed. 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.

Geotechnical field applications of AE/MS techniques at the Pennsylvania State University: a historical review

Since the early 1970s there has been an accelerating interest in the use of acoustic emission/microseismic (AE/MS) techniques for the laboratory and field investigation of geological materials and structures. Basic AE/MS research and the application of AE/MS techniques to a variety of geotechnical problems has been under way in the Penn State Rock Mechanics Laboratory since 1965. To date, studies have involved a wide variety of field topics, including: cavern stability, stability of natural gas storage reservoirs, strata control in longwall coal mines, rock bolt stability monitoring, effects of blasting, mine and tunnel roof stability, subsidence monitoring and rock slope stability evaluation. This paper reviews the development of AE/MS research at Penn State, describes briefly a number of the major field studies undertaken, and discusses on-going and future research programmes.

Experience in engineering evaluation of rock slope stability in the USSR : Gaziev, E G; Fisenko, G L; Grigorian, S S; Kazikaev, J M; Rechitski, V I; Zoteev, V G Proc 5th Congress of the International Society for Rock Mechanics, Melbourne, 10–15 April 1983V1, PC83–C91. Publ Rotterdam: A. A. Balkema, 1983

The report drawn up by a group of Soviet engineers generalizes experience in the analysis and strengthening of rock slopes in the USSR and the observed forms of failures. It gives a descriptive account of approaches to stability calculation, criteria, different procedures of stability analysis including calculation of rock failure-flows, mathematical statistics methods for the analysis of jointing, and the method of the probabilistic evaluation of the stability of rock masses. The number of the covering abstract of the congress is TRIS no. 385148. (TRRL)