Dynamic Slope Stability Research Articles

The effect of joint orientation and spacing on the dynamic stability of persistently-jointed rock slopes

The effect of joint orientation and spacing on the dynamic stability of persistently-jointed rock slopes

Dynamic factor of safety of rock slopes due to blasting based on critical displacement and critical acceleration

Analysis of slope stability due to blasting based on the pseudostatic principle is considered too conservative because the slope receives a constant maximum seismic load (and hence constant acceleration) without considering the duration of the blast. In reality, the acceleration fluctuates with time and eventually diminishes. One method to analyze the stability of rock slopes due to blasting is to conduct dynamic simulations using Newmark displacement analysis to obtain the dynamic Factor of Safety (FoS) based on the magnitude of critical displacement (ucrit ) and critical acceleration (acrit ). This study was carried out using hypothetical slopes of various rock mass strengths determined from the Rock Mass Rating (RMR). A case study of a highway rock slope excavated using the drill-and-blast method was also carried out to validate the research results. The findings reveal that very good rock (RMR Class I) has FoSdynamic = 11.7, ucrit = 6 mm, and acrit = 0.061g, while very poor rock (RMR V) has FoSdynamic = 1.7, ucrit = 16 mm, and acrit = 0.035g. This result indicates that the smaller the strength of the rock mass, the smaller the critical acceleration and the greater the value of the critical displacement will be. This study reinforces the significance of critical displacement and critical acceleration in assessing the dynamic stability of rock slopes due to blasting.

An Analytical Model for Assessing Dynamic Stability of Bedding Rock Slope with Soil Interlayer Under Different Rain Patterns

An Analytical Model for Assessing Dynamic Stability of Bedding Rock Slope with Soil Interlayer Under Different Rain Patterns

Seismic dynamic stability of double-slider rock slopes containing tension cracks

Seismic dynamic stability of double-slider rock slopes containing tension cracks

Dynamic stability analysis of jointed rock slopes using the combined finite-discrete element method (FDEM)

The combined finite-discrete element method (FDEM) is an advanced finite element and discrete element coupling method, which is commendably suitable for simulating the slope’s entire evolution process from cracking, expansion, penetration, sliding, collision to deposition under seismic load. The original FDEM has apparent shortcomings in simulating the dynamic instability process of earthquake-induced landslides, and some targeted improvements are made to the original program. Numerical tests are carried out to prove the accuracy and robustness of the improved FDEM, and the influence of the structural plane on the dynamic evolution mechanism and process of the slope is studied. The results show that the improved FDEM can accurately reproduce the entire dynamic evolution processes and failure forms of different jointed rock slopes under seismic load and can quantitatively evaluate the dynamic stability of jointed rock slopes (dynamic safety factor and critical failure surface). In addition, the results also emphasize that the slope failure degree significantly affects the dynamic response of the slope and suggest that the combination of the cut-through of the failure surface and the increase of kinetic energy should be used as the criteria for slope dynamic instability simulation by FDEM. This study provides scientific and technological support for revealing the failure mechanism of jointed rock slopes and disaster reduction and prevention.

Stability of Slopes under Dynamic Loading using FEM Software

Abstract: In this study, the dynamic stability of soil slopes was analysed using the finite element method (FEM). The analysis was performed using the Plaxis 2D software, which is a popular FEM software package. The study aimed to investigate the behaviour of soil slopes under dynamic loading conditions and to evaluate the accuracy and effectiveness of the FEM approach for predicting slope stability. A 2D slope model was created using Plaxis 2D, and dynamic analyses were performed under different loading conditions. A Shake Table was used for simulating the loading conditions at different frequencies and amplitude. The results of the analysis showed that the slope stability was highly dependent on the dynamic loading conditions and the soil properties. Under earthquake like ground motions which were simulated with the help of shake table under controlled environment, the slope experienced significant deformations and displacements. The deformations were calculated in the form of crest settlement and toe settlement. The study also evaluated the accuracy of the FEM approach by comparing the simulation results with the experimental data. The comparison showed that the FEM approach provided a good prediction of the slope behaviour under dynamic loading conditions and could be used as a reliable tool for analysing slope stability. Overall, the study demonstrated the effectiveness of the FEM approach for analysing the dynamic stability of soil slopes and highlighted the importance of considering dynamic loading conditions in slope stability analysis. The study also provided insights into the behaviour of soil slopes under different loading conditions and could be useful for designing safer and more stable slopes in practice.

Optimal Intensity Measures for Probabilistic Seismic Stability Assessment of Large Open-Pit Mine Slopes under Different Mining Depths

The dynamic stability of slopes is the key to ensure the safety of a large open-pit mine during and after a strong earthquake. This study was mainly focused on the identification of optimal intensity measures (IMs) for the probabilistic seismic stability assessment of large open-pit mine slopes within the framework of performance-based earthquake engineering (PBEE). To this end, four open-pit slopes with different mining depths were constructed as the reference cases for the numerical investigation. The randomness of input ground motions and the uncertainty of material properties of the slopes were also considered. A total of 96 ground-motion records and 29 common IMs were selected for testing. By a series of nonlinear time-history analyses, the probabilistic seismic demand models (PSDMs) between the minimum factor of safety (FOS) of slopes and all considered IMs were developed. The optimal IMs with respect to FOS were identified based on the evaluation of five criteria: correlation, efficiency, practicality, proficiency, and sufficiency. The impacts on seismic fragility and FOS response hazard of the slopes were discussed when using different IMs. The results reveal that sustained maximum velocity (SMV) and velocity spectrum intensity (VSI) are recognized as the optimal IM for a mining depth of 50 m and 100 m, respectively. However, Housner intensity (HI) is observed to have the best predictability for both the mining depths of 200 m and 300 m. Moreover, for the three most commonly used IMs, peak ground velocity (PGV) is superior to peak ground acceleration (PGA) and spectral acceleration at first mode period (Sa (T1)) for different mining depths. Finally, based on the evaluations of seismic fragility and FOS response hazard, the uncertainty of seismic stability prediction of open-pit slopes can be greatly reduced when using a more appropriate or optimal IM.

Reliability evaluation of reservoir bank slopes with weak interlayers considering spatial variability

Reservoir bank slopes with weak interlayers are common in the Three Gorges Reservoir area. Their stabilities are affected by multi-coupled factors (e.g., reservoir water fluctuations, rainfall, and earthquakes in the reservoir area). Meanwhile, the differences in mechanical parameters of reservoir banks make it more difficult to determine the dynamic stability of bank slopes under complex mechanical environments. In this paper, the multiple disaster-causing factors and spatial variability of the landslide were comprehensively considered to study the long-term evolution trend of the bank slopes with weak interlayers. Specifically, the limit equilibrium method combined with the random field was performed to calculate the reliability. Furthermore, the long-term effects of dry-wet cycles on reservoir bank landslides and the sensitivity analysis of the statistical parameters of the random field were discussed. The results show that the earthquake action had the most significant impact on the failure probability of the landslide. The failure probability was more significantly affected by the vertical fluctuation range of the parameters and the coefficient of variation of the internal friction angle. The increase in failure probability under the action of dry-wet cycles was mainly caused by the reduction of the parameters of the weak interlayer. The reliability evaluation method of reservoir bank slopes can be applied to predict the long-term stability of the coastal banks.

Long- and short-term dynamic stability of submarine slopes undergoing hydrate dissociation

Natural gas hydrates (NGHs) have recently been recognized as a promising source of relatively clean alternative energy and a significant factor in triggering marine geohazards. This paper presents a numerical method for calculating the transient excess pore pressure associated with hydrate dissociation in submarine sediments with THC (Thermo-Hydro-Chemical) coupling. Then, the dynamic stability of submarine slopes experiencing gas hydrate dissociation is evaluated based on limit equilibrium analysis considering the real evolution of excess pore pressure. Finally, this work is applied to investigate the dynamic responses of typical hydrate slopes in the Shenhu Sea area, South China Sea (SCS), under two different timescales: 1) Case I: gradual temperature increases at the seafloor due to climate warming and 2) Case II: sharp temperature increases in the interior of the hydrate deposit due to hydrate extraction. In Case Ⅰ, the timescale of hydrate dissociation is millennial. Due to the long-term temperature rise, the hydrate will dissociate slowly, which allows the generated free gas to migrate upwards and gradually accumulate at the transition zone between a porous layer and an overlying low-permeability layer. Eventually, the slow accumulation of free gas may lead to disc-shaped failure of the hydrate-bearing slope. In contrast, in Case Ⅱ, the temperature rises sharply over a short period of time, which leads to the drastic dissociation of the hydrate. The timescale of hydrate dissociation is decadal. As a result, the excess pore pressure accumulates rapidly. Under the influence of excess pore pressure, the sediment will deform dramatically, which may cause a penetration failure of the hydrate-bearing slope. These findings are relevant to the long-term (millennial) safety of human beings and short-term (decadal) utilization of energy resources.

Numerical Investigation of a Local Precise Reinforcement Method for Dynamic Stability of Rock Slope under Earthquakes Using Continuum–Discontinuum Element Method

The slope reinforcement scheme has an important influence on the prevention and control of landslides. A reasonable reinforcement scheme can improve the reliability, economy and efficiency of landslide resistance. It is urgent to establish a local precise reinforcement method for landslides on the basis of clear process and the instability modes of landslides. Taking a high-steep anti-dip rock slope as an example, six numerical models are established by using the continuum–discontinuum element method (CDEM) to carry out seismic damage and dynamic analysis of slopes. By comparing the seismic response and damage characteristics of being unstrengthened, local precise reinforcement and overall reinforcement models, the applicability of the proposed local precise reinforcement method for the slopes is discussed. The results show that the determination of the dynamic amplifying effect and seismic damage characteristics of slopes is the primary prerequisite of the local precise reinforcement method. The dynamic amplification effect of the slope toe, crest and shallow slope surface are much larger, that is, they are the potential reinforcement areas. The local precision reinforcement times should be controlled within a certain number of times, and the slope after the first three times of the local reinforcement effect is the best. However, more than three times after the reinforcement effect it becomes worse. Moreover, the dynamic amplification effect, the equivalent crack ratio and the mechanical energy of the slope after three times of local precision reinforcement are similar to the overall reinforcement effect, which indicates that local precision reinforcement has good feasibility. This work can provide references for landslide disasters prevention and control.

Study on the slope dynamic stability considering the progressive failure of the slip surface under earthquake

The strength of a rock-soil mass shows complex and obvious weakening characteristics under seismic dynamic load. The previous stability analysis methods of a seismic slope do not fully depict the attenuation law of geotechnical materials and cannot truly reflect the stable state of a slope under earthquake action. Based on the theoretical analysis of the progressive failure mechanism and the evolution law of a seismic slope, the adverse effect of progressive failure on slope stability is clarified. According to the progressive failure process of a slope under dynamic load, the strain-softening model and vibration deterioration model are introduced to represent the attenuation law of rock strength parameters, and a calculation method of seismic slope stability coupled with vibration disturbance and progressive failure is proposed. The method considers the strength parameter characteristics of a rock-soil mass in different stages and is combined with the vector sum method to obtain the time-history curve of the slope safety factor under earthquake action, which makes the evaluation result of slope stability more accurate and reliable. The numerical examples show that this method can effectively reflect the dynamic stability of seismic slopes, and solve the problem that the traditional calculation methods are difficult to characterize the strength attenuation characteristics of rock and soil mass. If these characteristics are not considered, the calculation results will be unsafe.

Investigation on the dynamic cumulative damage mechanism and stability of bedding rock slope under the deterioration of rock mass in the hydro-fluctuation belt

Investigation on the dynamic cumulative damage mechanism and stability of bedding rock slope under the deterioration of rock mass in the hydro-fluctuation belt

Probabilistic Seismic Hazard Analysis (PSHA) to estimate the input ground motions for Co-seismic landslide hazard assessment: A case study on Himalayan highways, Sikkim India

Sikkim, the North-Eastern state of India, along with its neighbouring region is recognized as a part of the ‘Alpine-Himalayan global seismic belt’, which is one of the most seismically active areas of the world. Four significant earthquakes with a magnitude higher than Mw = 8.0 were reported in this area in earlier years of 1897, 1905, 1934, and 1950. The 2011 (Mw = 6.9) Sikkim and 2015 (Mw = 7.8) Gorkha Nepal earthquakes call attention to the need for a more accurate understanding of seismic characteristics in the Sikkim and their nearby region to minimize loss of life and properties due to future earthquakes and related co-seismic hazards. This study aims to estimate the Peak Ground Acceleration (PGA) having a known Probability of Exceedance (PoE) along Gangtok to Lachung and Gangtok to Tsomgo Lake; two strategic highways within Sikkim. The PGA with a known PoE is an essential input required for earthquake-triggered landslide susceptibility analysis on a regional scale as well as for the dynamic slope stability assessment of the prevailing hill slopes along the highways corridor in Sikkim. Therefore, a Probabilistic Seismic Hazard Analysis (PSHA) of the highway corridors in Sikkim is presented utilizing the updated earthquake catalogue, modified seismic sources, and next-generation attenuation relationships. The Uniform Hazard Spectra (UHS) and total hazard curves corresponding to the bedrock site conditions are generated employing ‘EZ-FRISK’ software. The variations of PGA having a 10% PoE in 50-years along the highways are estimated to identify the critical sections based on the ground acceleration parameter.

DEM-Based Numerical Investigation of Seismic Stability of Rock Slope in Terms of Rigid Block Displacement

Abstract For the seismic behavior of a rock slope or more specifically a rock wedge, the limit equilibrium method is frequently utilized to determine the static and pseudo-static safety factor, and the Newmark method is usually applied to estimate the permanent dynamic displacement. However, the two methods are relatively complex, which negatively affects their usage in engineering practice. A new idea to analyze the static and dynamic stability of a complex rock slope was provided in this paper by combing the rigid discrete element method (DEM), shear strength reduction (SSR) method, and Newmark method. The research results show that (1) by setting the joint contact stiffness to a very large magnitude, the joint displacement caused by the reduction of joint contact stiffness during the SSR calculation process can be considered ignorable, making the contact behavior between the respective two joints approximately satisfy the rigid-plastic assumption. In this manner, it is feasible to calculate the static and pseudo-static safety factor (SF) and the permanent dynamic displacement of a rock wedge with the rigid DEM. (2) The SF and sliding forces of wedges can be directly calculated by this new method without any auxiliary assumption of motion direction or sliding type. Additionally, the new method is suitable for complex wedges, which is important to practical design. (3) The rigid DEM can be realized in 3DEC, which is testified in this paper by 5 classic static examples and 3 typical dynamic examples. (4) The effect of some important parameters, such as the excitation acceleration amplitude and dip of intersection line between two joints, on the dynamic displacement and SF under dynamic excitation was analyzed. The parameter analysis revealed that evaluating the seismic performance of a rock slope only with the pseudo-static SF would potentially underestimate the seismic displacement, under some special conditions. (5) An example case was presented in this paper that the seismic stability assessment of a block was performed with the proposed approach in terms of seismic displacement. And the slope reinforcement scheme was suggested with respect to exceedance probability. It is noted that the reinforcement scheme obtained from the rigid DEM has a better cost-saving benefit under the same SF. Overall, the knowledge gained in this paper may offer a new idea for the static and dynamic analysis to the rock slope stability.

Study on Dynamic Stability Prediction Model of Slope in Eastern Tibet Section of Sichuan-Tibet Highway

The stability of the slope along the middle section of Tibet controls the safety and smoothness of the Sichuan-Tibet highway, which is affected by multiple and uncertain factors such as rainfall. The slope dynamic stability is evaluated to the benefit of that salvager can prepare in advance and preserve timely and accurately. Therefore, engineering treatment scheme in different batches, stages, and grades can be proposed prospectively. Random Forest algorithm was used to rank 10 primary factors: precipitation, earthquake, human factors, groundwater, slope height, slope gradient, dense degree, weathering depth, vegetation, and slope shape. Considering precipitation and earthquake as dynamic factors, a wavelet and NARX dynamic neural network were used to predict the trend and quantity of precipitation and earthquake, followed by developing a dynamic stability evaluation model by combining a fuzzy neural network model with other indexes. Results show that (1) the superposition error in rainfall and earthquake prediction is 0.21%, proving that the ranking of influencing factors is reasonable, and (2) the back-judgment and test accuracy of the dynamic evaluation model are 93.98% and 91.67%, respectively, indicating that the model is accurate and applicable. The model can evaluate the dynamic stability of slopes and provide more reasonable engineering protection countermeasures so that Highway Public Works Department can deal with emergencies and disasters timely and precisely.

Dynamic Slope Stability Subject to Blasting Vibrations: a Case Study of the Jakarta-Bandung High-Speed Railway Tunnel

Dynamic Slope Stability Subject to Blasting Vibrations: a Case Study of the Jakarta-Bandung High-Speed Railway Tunnel

Study on Three-Dimensional Dynamic Stability of Open-Pit High Slope under Blasting Vibration

AbstractThe propagation process of blasting vibration has always been a difficult problem affecting the stability of high slopes in open-pit mines. Taking the Jianshan Phosphorus Mine as the research background, combined with engineering geological investigation, field blasting test, blasting vibration monitoring, numerical simulation technology, and theoretical analysis, the three-dimensional dynamic stability of the adjacent high slope after blasting vibration was systematically studied. In our study, a small-diameter buffer shock-absorbing blasting technology near the slope was proposed, which greatly improved the production efficiency. Through regression analysis of a large amount of vibration test data, the law of blasting vibration propagation in Jianshan stope and Haifeng stope was obtained. In addition, by establishing four three-dimensional geomechanical numerical models, the slope’s own frequency, damping characteristics, and dynamic response acceleration distribution after detonation were studied, respectively. On the other hand, under the action of Ei Centro wave with 8-degree seismic intensity, the maximum total acceleration and maximum total displacement of the slope were calculated and analyzed. Both the explosion unloading of the 8-degree earthquake and the Ei Centro wave simulation results showed that the high slope near the Jianshan Phosphorus Mine was generally in a stable state. Thus, this study can provide technical support and theoretical guidance for mine blasting.

Dynamic stability of rock slopes with hexagonal discontinuity pattern

Various regular discontinuity patterns are observed in rock masses and one of the common discontinuity patterns is hexagonal pattern, which is mostly observed in all extrusive volcanic rocks such as basalt, andesite, ryholite and welded tuffs as well as in some sedimentary rocks subjected to desiccation or freezing-thawing processes. In this study, the authors investigate the dynamic stability of rock slope consisting of hexagonal blocks through model tests on shaking table. Experiments indicated that toppling or sliding failures, which may be of active or passive modes occur. Critical acceleration levels can be estimated from the limit equilibrium method with the consideration of results of frictional properties and geometry of model slopes.

Investigation on the macro-meso fatigue damage mechanism of rock joints with multiscale asperities under pre-peak cyclic shear loading

The fatigue damage mechanical behaviours of rock joints under pre-peak cyclic shear loading are one of the key factors affecting the dynamic stability of slopes. In this study, the macro-meso fatigue damage mechanism of rock joints with multiscale asperities, when considerthe influence of the normal stress, shear rate, shear amplitude, first-order asperity angle, number of shear cycles and joint morphology, were investigated using experimental and numerical approaches under a constant normal load (CNL). The laboratory pre-peak cyclic shear experiments on the saw-tooth rock joints with different first-order asperity angles, i.e., 30°, 45° and 60°, and the same second-order asperity angle of 45°, were first conducted under different influence factors mentioned above. Six evolution stages of the shear stress with the shear displacement, i.e., initial nonlinear shear contraction deformation, approximate linear elastic shear dilation deformation, cyclic fatigue damage deformation, plastic deformation of the local compression-shear fracture, full plastic deformation of the stress brittle drop and ideal plastic flow deformation, were obtained. Additionally, the variation rules of the influence factors mentioned above with the peak (and residual) shear strengths and the cumulative shear (and normal) displacements were explored. Subsequently, the PFC2D discrete element method was used for the meso numerical simulations, in which the meso fatigue damage evolution processes of the saw-tooth and wavy rock joints were simulated considering more number of shear cycles. Meanwhile, the change rules of the meso fatigue damage crack number (and energy) with the shear displacement (and the number of cycles), and the distribution characteristics of the meso fatigue damage particles were observed. Based on the good agreement between the macro experimental results and the meso numerical observations, the macro-meso fatigue damage failure modes of rock joints can be generally summarized as three basic types, i.e., compacting – climbing failure mode, climbing – cyclic abrading – extruding – gnawing failure mode and gnawing – sliding failure mode.

Geotechnical Investigation and Numerical Analysis of Slope Failure: A Case Study of Landslide Vulnerability Zone in Kolli Hills, Tamil Nadu

Abstract Landslides are the downward movement of materials under the influence of gravity when shear stress exceeds the shear strength of the material. It includes various movements resulting in complex type of slope failures which commonly occurred on cut slopes of Ghat roads in mountaneous region. The study area chosen for the geotechnical investigation is Kolli hills situated in the tail end of the Eastern Ghats in Namakkal district of Tamil Nadu, India. The ghat road section of 20 km stretch along with 70 hairpin bends, connects the foothills at Karavallikkombai to Sholaikkadu at the top is selected for the present study. The hill is situated at a fault zone which is extended from Mettur dam, Salem district, Tamil Nadu. In this study, undisturbed soil samples were collected from 10 landslide locations and tested for its index and engineering properties. Based on the test results, static slope stability analysis using Modified Bishop method and dynamic slope stability analysis using Simplified Newmark method were carried out to find out factor of safety of the slopes which is used to derive the slope stability assessment of the study area. The landslide hazard zone assessment was carried out to identify the landslide prone areas.