Deformation Mechanism Of Slope Research Articles

Slope Deformation Mechanisms and Stability Assessment under Varied Conditions in an Iron Mine Waste Dump

The instability of geological slopes in mining environments poses a significant challenge to the safety and efficiency of operations. Waste Dump#2 at the Ziluoyi Iron Mine in China is a notable case study that highlights the challenges associated with sizable base slopes and large step heights. To address hidden hazards in the mine and the above issues, an inclusive investigation is carried out to examine the physical and mechanical properties of the soil–rock slope through indoor testing and analyze the deformation mechanisms of the slope using numerical simulations, taking various factors into account. The study reveals that the stability of Waste Dump#2 is deeply affected by weight, groundwater conditions, earthquake loading, and rainfall. To this end, the cohesion and internal friction parameters of the soil–rock slope are first determined through direct shear tests, which show a cohesion of 6.215 kPa at the top of the slope and an internal friction angle of 34.12°. By adopting GEO-SLOPE, 3D Mine, and AutoCAD software, stability calculations of the slope are performed, which give stability coefficients of 1.547 under normal conditions, 1.276 in rainfall, and 1.352 in seismic conditions. These results meet safety standards and ensure the safe and efficient operation of the mine.

Estimation of Uncertainties in Soil Using MCMC Simulation and Effect of Model Uncertainty

The simulation of field conditions for seismically induced slope failures incorporates model uncertainties, which account for the difference between simulated and observed slope behaviour. The quantification of this uncertainty is mandatory to understand the field response of the geotechnical system and make decisions for geotechnical systems. Previous studies have partially studied uncertainty for slope systems under seismic loading. To this aim, this study proposes a methodology based on probabilistic back analysis to estimate uncertainties in soil parameters considering the observed slope response under seismic loading. The proposed method involves support vector regression (SVR) model to map the relationship between soil parameters and seismically induced slope displacement. The SVR model is generated using the data from the numerical simulation of slope system under seismic loading using FLAC 2D. Further, the developed SVR model is used for probabilistic back analysis using Markov Chain Monte Carlo (MCMC) simulation. The Noto Hanto earthquake in 2007 and the subsequent slope failure along Noto Yuryo Road, Japan, are considered as a case study to validate the proposed methodology. The results of the case study show that the updated or inferred soil parameters have less variability than the prior distribution. Further, the uncertainties in the slope system influence the inferred soil parameters. Hence, a parametric study is conducted to investigate the effect of model uncertainty on the posterior statistics of soil parameters. The study results facilitate a better understanding of the slope deformation mechanism and the effect of model uncertainty on the updated statistics of soil parameters.

Gravitational Deformation and Reactivation Mechanism of a Fault-Bounded Slope, Eastern Yanshan Mountains, China

The Nandongzi landslide occurred in the Yanshan region of North China. From 2017, the slope of the Nandongzi landslide has been significantly deformed after several excavations. Field investigations show that the Nandongzi landslide is a special toppling deposit that does not have basic toppling conditions. The toppling deformation mechanism of the slope has become a difficult issue for engineers, attracting the attention of scientists. Joint, surface, and borehole lithology surveys revealed the surface and internal structural characteristics of the slope. The structure of the soft and hard interbedded rock and the proximity of the fault are the dominant factors of slope toppling deformation. The slope toppling failure process can be divided into four stages: initial deformation, compression and bending, toppling and overlapping, and reactivation. In the first three stages, slope toppling deformation is triggered by the downcutting of the upstream gully, gravity, and differential weathering of soft and hard rocks, which promote the dumping deformation of the slope. In the final stage, engineering excavations triggered the reactivation of residual deposits. Monitoring data indicate that slope deformation is directly related to rainfall events. Flac 3D was used to simulate the slope failure process under natural and rainfall conditions after the two excavations. The results show that multiple excavations changed the surface and runoff conditions of the slope, which led to slope failure. Rainfall promoted deformation of the back edge of the landslide, which led to shear failure from the back edge to the front edge. Our results provide new and unique understanding into the spatiotemporal evolution and deformation mechanism of similar toppling-accumulation landslides around the study area.

A complex slope deformation case—history

Slope movements represent a class of phenomena, which can display a great variety of styles, sizes and displacement rates. Some are extremely rapid, short-lived and highly destructive; others are extremely slow and apparently endless. This paper describes an extremely slow soil slope deformation process that is probably active since thousands of years and will certainly go on for many years to come. The results of in-depth investigations carried out after the 1980 Irpinia-Basilicata earthquake integrated by satellite images covering the time interval 1992–2013 have provided a global and consistent framework that allows to draw a reliable scenario about the effects of the geological processes that are active in the area on slope deformation mechanisms.

An Integrated InSAR-Borehole Inclinometer-Numerical Modeling Approach to the Assessment of a Slow-Moving Landslide

ABSTRACT We use results of satellite-based interferometric synthetic aperture radar, Global Positioning System, and borehole inclinometer data to constrain numerical models that improve understanding of slope deformation at the Alexandria landslide, British Columbia, Canada. Surface monitoring data and borehole slope inclinometer measurements provide important insight into the slope failure mechanism. We initially analyzed the data in a geographic information system (GIS) to create thematic maps of the landslide area (hillshade, slope, and aspect), to identify key geological features, and to produce an engineering geomorphology map of the landslide. The monitoring data and the geological/engineering geomorphological models provide important constraints for two-dimensional landslide limit equilibrium and finite difference analyses. The initial limit equilibrium analysis improved understanding of the sliding surfaces. The finite difference models were then used to simulate and investigate the potential slope deformation mechanism. The combined slope monitoring/modeling results show that the Alexandria landslide is a slow-moving, multiple-block, retrogressive slope failure. The close agreement between the limit equilibrium and finite difference analyses, together with the satellite and ground-based slope monitoring and GIS data, highlight the importance of using a multidisciplinary/integrated approach in landslide studies.

Numerical Analysis and Deformation Mechanism Study on an Excavated High-Steep Slope of a Hydropower Station

The high-steep rock slope stability is one of the key technologies in the construction of water conservancy and hydropower projects, which affects and restricts the development of hydraulic resources and the construction of hydropower projects. In this paper, a three-dimensional numerical model was built incorporating stratigraphy, geological structures, and the inverted rock mechanical parameters to perform displacement, stress, and plastic zone analyses for an excavated slope in China using the FLAC3D software. The numerical simulation results after slope excavation show that the deformation near the fault fracture zone is the largest, ranging from 350 mm to 380 mm. The compressive stress is concentrated on the slope foot and the connecting part, the stress value is 2 MPa∼5 MPa, there is a large tensile stress area in the slope, and the tensile stress value is 0 MPa∼0.4 MPa. The plastic zone of the slope is concentrated near the fault F6 and the structural influence zone, and the rock mass of the slope basically enters the plastic state. On this basis, the deformation mechanism of slope was analyzed, while the internal and external factors affecting the slope deformation were described in detail. This work would provide an effective reference basis for slope stability evaluation and treatment of similar hydropower stations.

Surface mines composite slope deformation mechanisms and stress distribution

Surface mines composite slope deformation mechanisms and stress distribution

SPH Simulation on the Coupled Failure of Slope-Building Adjacent to Water Triggered by the Rapid Drawdown of Water Level

With the development of economy, more and more buildings are constructed on both sides of rivers. The rapid drawdown of water level may induce the change of groundwater seepage in the river bank, thus affecting the stability of buildings on the bank. In this study, the right bank of Qinhuai river with its ancillary building from the Dinghuai Gate to the Qingliang Gate in Nanjing City is analyzed to reveal the failure mechanism and coupled failure mode of slope and building adjacent to water. The soil-water coupled SPH program considering the interaction between soil and structure has been proposed. Then this model is used to study the evolutionary deformation mechanism of slope and building under the rapid drawdown of water level. The results indicate that the potential slip surface of slope and the asymmetrical distribution of plastic zone in the foundation of building become more obvious under the rapid drawdown of water level. Besides, the differential settlement of building induced by the rapid drawdown causes the building tilt. When the sliding surface of the slope passes the building, the differential settlement will become larger. This study is conducive to reveal the coupled failure mechanism of slope and building and also to provide scientific basis for the prevention of such disasters.

Analysis of acoustic emission patterns for monitoring of rock slope deformation mechanisms

Acoustic emission (AE) is generated in soil and rock materials by rearrangement of particles during displacement or increasing damage in the microstructure preceding a collapse; therefore AE is appropriate for estimation of slope degradation. To overcome the high attenuation that characterise geological materials and thus to be able to monitor AE activity, a system that makes use of a waveguide to transmit AE waves from a deforming zone to a piezoelectric transducer was developed. The system quantifies acoustic activity as Ring Down Count (RDC) rates. In soil applications RDC rates have been correlated with the rate of deformation, whereas the recent application to rock slopes requires new interpretation strategies. In order to develop new strategies the system was installed at two rock slope trial sites in Italy and Austria. RDC rates from these sites, which have been measured over 5 and 1.5years respectively, are analysed and clear and recurring trends are identified. The comparison of AE trends with response from a series of traditional instruments available at the sites allows correlation with changes in external slope loading and internal stress changes. AE signatures from the large rock slope in Italy have been identified as generated in response to variations in the groundwater level and snow loading. At the slope in Austria, AE signatures include the detachment of small boulders from the slope surface caused by the succession of freeze-thaw cycles during winter time. The work reported in this paper is contributing to the development of AE monitoring and interpretation strategies for rock slopes. The longer-term aim is to identify approaching failures and derive rules for setting thresholds that can be used to give warning of rock slope failures in time to enable action to be taken.

Numerical Simulation Analysis of Reservoir Bank Fractured Rock-Slope Deformation and Failure Processes

The fluctuations of reservoir water levels significantly change the hydrogeological conditions of reservoir banks and thus affect the steady state of the bank slope. Reservoir landslide stability is governed by the complex interactions between the rock and the water (both reservoir and pore water). This paper establishes the constitutive coupled model of seepage and stress field for the E20 bank slope in the Haizhou Open Pit Coal Mine hydropower station’s lower reservoir. Using the geotechnical engineering three-dimensional fast Lagrangian analysis of continua (FLAC-3D 4.0) program as a computational analysis tool, the E20 bank slope deformation mechanism was analyzed. The simulation model, calculated by using the Boit consolidation and pore-water continuity principles, was built using FEMs. The numerical simulation results showed that cyclical fluctuations and speeds of the reservoir’s water level affect its bank slope stability. When the water level drops at a speed of 12 m/day, the simulation’s calculated safety factor value is 0.99, but when the water level rises at a speed of 12 m/day, the calculated safety factor value is 1.03. The results demonstrated that the rapid drop of the water level had a greater impact on the reservoir bank slope stability than the rapid rise of the water level under the same conditions.

Application of 3D numerical methods to the design of high rock slopes

This paper deals with the deformation mechanisms and stability analysis of large slopes. The Sarcheshmeh mine west wall was selected as a case study. The current height of Sarcheshmeh west wall is 450 m, and in the future planning, pit depth exceeds over 800 m. With regard to the high future west wall (up to 1000 m), a comprehensive stability analysis was conducted. A sophisticated 3D model of the west wall was constructed and a comprehensive stress analysis was conducted. Both current and future slope geometries were analyzed, and the slope deformation mechanisms and stress change history were investigated as a function of slope excavation. The effect of regional in situ stress regime on the wall stability was demonstrated. Numerical modeling results are in agreement with field observations and predict instabilities for the midsection of Sarcheshmeh west wall.

Rock slope deformation mechanism in the Cihaxia Hydropower Station, Northwest China

Complex block-flexure slope toppling is observed in interbedded sandstone and slate in the upper Yellow River, China. Block toppling is observed in the relatively hard sandstone and flexural toppling is observed in the relatively soft slate. The evolution of toppling slope deformation is characterized by long-term progress and spatial variability. In order to study these characteristics, field investigations, adit prospecting, borehole drilling, sonic tests and numerical simulation were carried out. In addition, the effect of the structure, the composite mode of the rock mass, the unloading fissures and geomorphology are discussed. Furthermore, we explored the toppling mechanisms and simulated it numerically; on this basis, the slope evolution is divided into four stages. Results obtained from the numerical simulation compared well with field investigation data (investigation data, rock sonic survey and strata dip statistics). Comparative studies have demonstrated that the analytical methods presented in this paper are appropriate for back analysis of the toppling evolution process. The result showed that this toppling slope has not yet entered the later progressivity failure stage and is currently limited to collapse at shallow levels, whereas the deep-seated rock mass will remain stable for a long time. This study might provide reference for a stability evaluation and hazard prevention analysis for rock toppling.

The Stability Analysis of Over-Dip Stratoid Structure Rock Slope

The rock mass structure of granite is massive, so the stability of granite slope is good. Massive rock become stratoid structure when the rock mass contain discontinuities such as joints and faults. The deformation and destruction of the slope rock mass is controlled by the behaviour and orientation of the discontinuities. Especially, the over-dip discontinuities controlled the slope stability. In this paper, based on the abundant field investigation on the slope in left bank diversion tunnel inlets of Nuozadu power station in Lancang River, the types of rock mass structures and the combination between structural planes and slope surface are studied in detail so as to analyze the slope deformation mechanism. Finally, the slope stability is researched systematically by limit equilibrium method and FLAC numerical simulation analysis. A set of technical and methodological system on stability research of over-dip stratoid structure rock slope will hoped to be established.