Block-flexure toppling constitutes the predominant form of toppling failure in rock slopes.Although it has been extensively studied,the current theoretical models are often oversimplified by treating rock layers as ri...Block-flexure toppling constitutes the predominant form of toppling failure in rock slopes.Although it has been extensively studied,the current theoretical models are often oversimplified by treating rock layers as rigid bodies that diverge from actual conditions.The proposed Equivalent Deformation Compatibility Method(EDCM)offers a fresh approach to assess the stability of rock slopes prone to block-flexure toppling.EDCM posits that blocky rock layers,with their inability to withstand significant bending and role in merely transferring forces,can be modeled as intact layers with a reduced modulus.The method simplifies the complex issue of analyzing discrete and continuous rock layers to the study of layered soft and hard rock,establishing deformation compatibility equations subsequently.Validation of the EDCM was achieved through numerical models,physical model testing,and application to an actual slope.The factor of safety(FS)for slopes corresponds with the results from both models and the actual slope,demonstrating the method's applicability for evaluating susceptibility to block-flexure toppling.When applying the EDCM,it is advised to set the elastic modulus reduction coefficient for blocky layers at a value below 0.1.展开更多
Rock slopes with large intersection angles between the strikes of strata and surface(RS-LISS)represent a unique type of layered rock slope.These slopes are usually considered to be well stabilized and less prone to la...Rock slopes with large intersection angles between the strikes of strata and surface(RS-LISS)represent a unique type of layered rock slope.These slopes are usually considered to be well stabilized and less prone to landslides.However,when such slopes contain a significant number of discontinuities,their stability is greatly weakened.This study provided innovative insights into the stability of RS-LISS and conducted an in-depth investigation of their step-path failure mechanisms.The Riyi landslide on the eastern margin of the Qinghai-Tibet Plateau,China,was taken as a typical case and detailed investigations of geological structure and deformation characteristics of the slope were conducted by means of slope mapping,core drilling,and exploratory adits.A large number of steep-dip and gentle-dip joints were discovered in the slope,along with several critical discontinuities such as faults.Analysis shows that the tectonic stresses and river downcutting over geological time played significant roles in the formation of these discontinuities.Based on the investigation results,a numerical model of DFN for the Riyi landslide was developed.The simulation results indicated that the slope could develop a sliding surface characterized by a steep back and a gentle base,formed through the stepped interconnection of various discontinuities.Additionally,the deformation of the rock mass mainly originated from the major fault,progressively extending downward.The sliding mass may slide suddenly as a whole along the stepped bottom surface,with the compressional fracture zones as lateral boundaries,presenting a"drawer-like"movement towards the free surface.展开更多
Accurate identification and effective support of key blocks are crucial for ensuring the stability and safety of rock slopes.The number of structural planes and rock blocks were reduced in previous studies.This impair...Accurate identification and effective support of key blocks are crucial for ensuring the stability and safety of rock slopes.The number of structural planes and rock blocks were reduced in previous studies.This impairs the ability to characterize complex rock slopes accurately and inhibits the identification of key blocks.In this paper,a knowledge-data dually driven paradigm for accurate identification of key blocks in complex rock slopes is proposed.Our basic idea is to integrate key block theory into data-driven models based on finely characterizing structural features to identify key blocks in complex rock slopes accurately.The proposed novel paradigm consists of(1)representing rock slopes as graph-structured data based on complex systems theory,(2)identifying key nodes in the graph-structured data using graph deep learning,and(3)mapping the key nodes of graph-structured data to corresponding key blocks in the rock slope.Verification experiments and real-case applications are conducted by the proposed method.The verification results demonstrate excellent model performance,strong generalization capability,and effective classification results.Moreover,the real case application is conducted on the northern slope of the Yanqianshan Iron Mine.The results show that the proposed method can accurately identify key blocks in complex rock slopes,which can provide a decision-making basis and rational recommendations for effective support and instability prevention of rock slopes,thereby ensuring the stability of rock engineering and the safety of life and property.展开更多
The discrete fracture system of a rock mass plays a crucial role in controlling the stability of rock slopes.To fully account for the geometric shape and distribution characteristics of jointed rock masses,terrestrial...The discrete fracture system of a rock mass plays a crucial role in controlling the stability of rock slopes.To fully account for the geometric shape and distribution characteristics of jointed rock masses,terrestrial laser scanning(TLS)was employed to acquire high-resolution point-cloud data,and a developed automatic discontinuity-identification technology was coupled to automatically interpret and characterize geometric information such as orientation,trace length,spacing,and set number of the discontinuities.The discrete element method(DEM)was applied to study the influence of the geometric morphology and distribution characteristics of discontinuities on slope stability by generating a discrete fracture network(DFN)with the same statistical characteristics as the actual discontinuities.Based on slope data from the Yebatan Hydropower Station,a simulation was conducted to verify the applicability of the automatic discontinuity identification technology and the discrete fracture network-discrete element method(DFN-DEM).Various geological parameters,including trace length,persistence,and density,were examined to investigate the morphological evolution and response characteristics of rock slope excavation under different joint combination conditions through simulation.The simulation results indicate that joint parameters affect slope stability,with density having the most significant impact.The impact of joint parameters on stability is relatively small within a reasonable range but becomes significant beyond a certain threshold,further validating that the accuracy of field geological surveys is critical for simulation.This study provides a scientific basis for the construction of complex rock slope models,engineering assessments,and disaster prevention and mitigation,which is of great value in both theory and engineering applications.展开更多
Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain...Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain poorly understood.In this study,finite element method-based numerical simulations were conducted based on the rock slope at Dagangshan Hydropower Station in Sichuan province,China.Firstly,systematic analysis in both the time and frequency domains were performed to examine the seismic dynamic characteristics of the slope.Subsequently,the transfer function method and the multiple stepwise linear regression method were employed to clarify the underlying mechanism and determine critical factors influencing the slope instability during earthquakes.Time-domain analysis reveals that rock slope dynamic response exhibits notable elevation,surface,and local amplification effects.Specifically,the Peak Ground Acceleration(PGA)amplification coefficient(MPGA)is significantly higher at elevated locations,near the slope surface and in areas with protrusions.Moreover,the existence of fracture zones and anti-shear galleries minimally influences the dynamic responses but considerably affect the rupture.Specifically,fracture zones exacerbate rupture,while anti-shear galleries mitigate it.Frequency-domain analysis indicates that the dynamic responses of the slope are closely correlated with the degree of slope rupture.As earthquake magnitude increases,the rupture degree of the slope intensifies,and the dominant frequency of the response within the slope decreases,e.g.,its value shifts from 3.63 to 2.75 Hz at measurement point 9near the slope surface.The transfer function of rock slope,calculated under the excitation of wide flat spectrum white noise can reflect the interrelationships between the inherent properties and the rupture degree.Notably,the peak of the transfer function undergoes inversion as the degree of rupture increases.Furthermore,through multiple stepwise linear regression analysis,four key factors influencing the surface dynamic response of the slope were identified:rock strength,slope angle,elevation,and seismic dominant frequency.These findings provide valuable insights into the underlying mechanisms of rock slope dynamic responses triggered by earthquakes,offering essential guidance for understanding and mitigating seismic impacts on rock slopes.展开更多
Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects...Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects as static loads often underestimates rock slope stability.The development of a practical stability analysis approach for ABRSs,particularly in slope engineering design,is imperative.This study proposes a stability evaluation model for ABRSs,incorporating the viscoelastic properties of rock,to quantitatively assess the safety factor and failure surface under seismic conditions.The mathematical description of the pseudo-dynamic method,derived in this study,accounts for the viscoelastic properties of ABRSs and integrates the HoekeBrown failure criterion with the Kelvin-Voigt stress-strain relationship of rocks.Furthermore,to address concurrent translation-rotation failure in ABRSs,upper bound limit analysis is utilized to quantify the safety factor.Through a comparison with existing literature,the proposed method considers the effect of harmonic vibration on the stability of ABRSs.The obtained safety factor is lower than that of the quasi-static method,with the resulting percentage change exceeding 5%.The critical failure surface demonstrates superior positional accuracy compared to the Aydan and Adhikary basal planes,with minimal error observed between the physical model test and the numerical simulation test.The parameter sensitivity analysis reveals that the inclination of ABRSs exhibits the highest sensitivity(Sk)value across the three levels of horizontal seismic coefficient(kh).The study aims to devise an expeditious calculation approach for assessing the stability of ABRSs during seismic events,intending to offer theoretical guidance for their stability analysis.展开更多
Rock slopes are usually reinforced by a number of rock bolts due to the high efficiency and low price.However,where should the rock bolts be installed is still a troublesome issue.For anti-dip bedding rock slopes(ABRS...Rock slopes are usually reinforced by a number of rock bolts due to the high efficiency and low price.However,where should the rock bolts be installed is still a troublesome issue.For anti-dip bedding rock slopes(ABRSs),the installation position of rock bolts is a controlling factor that determines the reinforcement effect.In this work,a theoretical method is firstly proposed for assessing the stability of ABRSs reinforced by rock bolts using a limit equilibrium model.A comparison of theoretical calculations and numerical results was conducted to test the correctness of the theoretical method.Based on the stability assessment of ABRSs,we introduce adaptive moment estimation method(Adam)to optimize the installation location of rock bolts.Using Adam optimizer,the optimal layout of rock bolts with the maximum factor of safety can be determined,and the factor of safety of the slope increases by about 25%using the same amount of rock bolts but with different installation locations.The proposed method enables the fast stability analysis and supporting design for reinforced ABRSs,which paves the way to smart supporting design of slopes.展开更多
Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads....Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads.Three models of typical bedded rock slopes(BRSs),i.e.gently(GIS),moderately(MIS),and steeply(SIS)inclined slopes,were proposed according to field investigations.The dynamic response mechanism and stability of the BRSs,affected by the rock mass deterioration of the HFB,were investigated by the shaking table test and the universal distinct element code(UDEC)simulation.Specifically,the amplification coefficient of the peak ground acceleration(PGA)of the slope was gradually attenuated under multiple seismic loads,and the acceleration response showed obvious“surface effect”and“elevation effect”in the horizontal and vertical directions,respectively.The“S-type”cubic function and“steep-rise type”exponential function were used to characterize the cumulative damage evolution of the slope caused by microseismic waves(low seismic waves)and high seismic waves,respectively.According to the dynamic responses of the acceleration,cumulative displacement,rock pressure,pore water pressure,damping ratio,natural frequency,stability coefficient,and sliding velocity of the slope,the typical evolution processes of the dynamic cumulative damage and instability failure of the slope were generalized,and the numerical and experimental results were compared.Considering the dynamic effects of the slope height(SH),slope angle(SA),bedding plane thickness(BPT),dip angle of the bedding plane(DABP),dynamic load amplitude(DLA),dynamic load frequency(DLF),height of water level of the hydro-fluctuation belt(HWLHFB),degradation range of the hydro-fluctuation belt(DRHFB),and degradation shape of the hydro-fluctuation belt(DSHFB),the sensitivity of factors influencing the slope dynamic stability using the orthogonal analysis method(OAM)was DLA>DRHFB>SA>SH>DLF>HWLHFB>DSHFB>DABP>BPT.展开更多
In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermitt...In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.展开更多
Bedding rock slopes are common geological features in nature that are prone to failure under strong earthquakes. Their failures induce catastrophic landslides and form barrier lakes, posing severe threats to people’s...Bedding rock slopes are common geological features in nature that are prone to failure under strong earthquakes. Their failures induce catastrophic landslides and form barrier lakes, posing severe threats to people’s lives and property. Based on the similarity criteria, a bedding rock slope model with a length of3 m, a width of 0.8 m, and a height of 1.6 m was constructed to facilitate large-scale shaking table tests.The results showed that with the increase of vibration time, the natural frequency of the model slope decreased, but the damping ratio increased. Damage to the rock mass structure altered the dynamic characteristics of the slope;therefore, amplification of the acceleration was found to be nonlinear and uneven. Furthermore, the acceleration was amplified nonlinearly with the increase of slope elevation along the slope surface and the vertical section, and the maximum acceleration amplification factor(AAF) occurred at the slope crest. Before visible deformation, the AAF increased with increasing shaking intensity;however, it decreased with increasing shaking intensity after obvious deformation. The slope was likely to slide along the bedding planes at a shallow depth below the slope surface. The upper part of the slope mainly experienced a tensile-shear effect, whereas the lower part suffered a compressive-shear force. The progressive failure process of the model slope can be divided into four stages, and the dislocated rock mass can be summarized into three zones. The testing data provide a good explanation of the dynamic behavior of the rock slope when subjected to an earthquake and may serve as a helpful reference in implementing antiseismic measures for earthquake-induced landslides.展开更多
Two critical factors,namely intense precipitation and intricate excavation,can trigger rock mass disasters in mining operations.In this study,an indoor rainfall system was developed to precisely regulate the flow and ...Two critical factors,namely intense precipitation and intricate excavation,can trigger rock mass disasters in mining operations.In this study,an indoor rainfall system was developed to precisely regulate the flow and intensity of precipitation.A large-scale model experiment was conducted on a self-designed physical simulation experiment platform to investigate the failure and instability of high-steep rock slopes under unsaturated conditions.The real-time reproduction of the progressive failure process in high-steep rock slopes enabled the determination of the critical rainfall intensity and revealed the mechanism underlying slope instability.Experiment results indicated that rainfall may be the primary factor contributing to rock mass instability,while continuous pillar mining exacerbates the extent of rock mass failure.The critical failure stage of high-steep rock slopes occurs at a rainfall intensity of 40 mm/h,whereas a rainfall exceeding 50 mm can induce critical instability and precipitation reaching up to 60 mm will result in slope failure.The improved region growing segmentation method(IRGSM)was subsequently employed for image recognition of rock mass deformation in underground mines.Herein an error comparison with the simple linear iterative cluster(SLIC)superpixel method and the original region growing segmentation method(ORGSM)showed that the average identification error in the X and Y directions by the method was reduced significantly(1.82%and 1.80%in IRGSM;4.70%and 6.26%in SLIC;9.45%and 12.40%in ORGSM).Ultimately,the relationship between rainfall intensity and failure probability was analyzed using the Monte Carlo method.Moreover,the stability assessment criteria of rock slope under unsaturated condition were quantitatively and accurately evaluated.展开更多
For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of ...For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of water level in the service lifetime of slopes. According to the concept that the progressivedamage （microseismicity） of rock slope is the essence of the precursor of slope instability, a microseismicmonitoring system for high-steep rock slopes is established. Positioning accuracy of the monitoringsystem is tested by fixed-position blasting method. Based on waveform and cluster analyses of microseismicevents recorded during test, the tempo-spatial distribution of microseismic events is analyzed.The deformation zone in the deep rock masses induced by the microseismic events is preliminarilydelimited. Based on the physical information measured by in situ microseismic monitoring, an evaluationmethod for the dynamic stability of rock slopes is proposed and preliminarily implemented bycombining microseismic monitoring and numerical modeling. Based on the rock mass damage modelobtained by back analysis of microseismic information, the rock mass elements within the microseismicdamage zone are automatically searched by finite element program. Then the stiffness and strengthreductions are performed on these damaged elements accordingly. Attempts are made to establish thecorrelation between microseismic event, strength deterioration and slope dynamic instability, so as toquantitatively evaluate the dynamic stability of slope. The case studies about two practical slopes indicatethat the proposed method can reflect the factor of safety of rock slope more objectively. Numericalanalysis can help to understand the characteristics and modes of the monitored microseismic events inrock slopes. Microseismic monitoring data and simulation results can be used to mutually modify thesensitive rock parameters and calibrate the model. Combination of microseismic monitoring and numericalsimulation provides a more objective basis for the numerical model and parameters and a solidmechanical foundation for the microseismic monitoring.展开更多
Several potential failure modes generally exist in rock slopes because of the existence of massive structural planes in rock masses. A system reliability analyses method for rock slopes with multiple failure modes bas...Several potential failure modes generally exist in rock slopes because of the existence of massive structural planes in rock masses. A system reliability analyses method for rock slopes with multiple failure modes based on nonlinear Barton-Bandis failure criterion is proposed. The factors of safety associated with the sliding and overturning failure modes are derived, respectively. The validity of this method is verified through a planar rock slope with an inclined slope top and tension crack. Several sensitivity analyses are adopted to study the influences of structural-plane parameters, geometric parameters, anchoring parameters and fracture morphology on the rock slopes system reliability.展开更多
Seismic stability of slopes has been traditionally analyzed with vertically propagated earthquake waves.However,for rock slopes,the earthquake waves might approach the outcrop still with a evidently oblique direction....Seismic stability of slopes has been traditionally analyzed with vertically propagated earthquake waves.However,for rock slopes,the earthquake waves might approach the outcrop still with a evidently oblique direction.To investigate the impact of obliquely incident earthquake excitations,the input method for SV and P waves with arbitrary incident angles is conducted,respectively,by adopting the equivalent nodal force method together with a viscous-spring boundary.Then,the input method is introduced within the framework of ABAQUS software and verified by a numerical example.Both SV and P waves input are considered herein for a 2 D jointed rock slope.For the jointed rock mass,the jointed material model in ABAQUS software is employed to simulate its behavior as a continuum.Results of the study show that the earthquake incident angles have significance on the seismic stability of jointed rock slopes.The larger the incident angle,the greater the risk of slope instability.Furthermore,the stability of the jointed rock slopes also is affected by wave types of earthquakes heavily.P waves induce weaker responses and SV waves are shown to be more critical.展开更多
Safety evaluation of toppling rock slopes developing in reservoir areas is crucial. To reduce the uncertainty of safety evaluation, this study developed a composite cloud model, which improved the combination weights ...Safety evaluation of toppling rock slopes developing in reservoir areas is crucial. To reduce the uncertainty of safety evaluation, this study developed a composite cloud model, which improved the combination weights of the decision-making trial and evaluation laboratory (DEMATEL) and criteria importance through intercriteria correlation (CRITIC) methods. A safety evaluation system was developed according to in situ monitoring data. The backward cloud generator was used to calculate the numerical characteristics of a cloud model of quantitative indices, and different virtual clouds were used to synthesize some clouds into a generalized one. The synthesized numerical characteristics were calculated to comprehensively evaluate the safety of toppling rock slopes. A case study of a toppling rock slope near the Huangdeng Hydropower Station in China was conducted using monitoring data collected since operation of the hydropower project began. The results indicated that the toppling rock slope was moderately safe with a low safety margin. The composite cloud model considers the fuzziness and randomness of safety evaluation and enables interchange between qualitative and quantitative knowledge. This study provides a new theoretical method for evaluating the safety of toppling rock slopes. It can aid in the predication, control, and even prevention of disasters.展开更多
The key-blocks are the main reason accounting for structural failure in discontinuous rock slopes, and automated identification of these block types is critical for evaluating the stability conditions. This paper pres...The key-blocks are the main reason accounting for structural failure in discontinuous rock slopes, and automated identification of these block types is critical for evaluating the stability conditions. This paper presents a classification framework to categorize rock blocks based on the principles of block theory. The deep convolutional neural network(CNN) procedure was utilized to analyze a total of 1240 highresolution images from 130 slope masses at the South Pars Special Zone, Assalouyeh, Southwest Iran.Based on Goodman’s theory, a recognition system has been implemented to classify three types of rock blocks, namely, key blocks, trapped blocks, and stable blocks. The proposed prediction model has been validated with the loss function, root mean square error(RMSE), and mean square error(MSE). As a justification of the model, the support vector machine(SVM), random forest(RF), Gaussian naïve Bayes(GNB), multilayer perceptron(MLP), Bernoulli naïve Bayes(BNB), and decision tree(DT) classifiers have been used to evaluate the accuracy, precision, recall, F1-score, and confusion matrix. Accuracy and precision of the proposed model are 0.95 and 0.93, respectively, in comparison with SVM(accuracy = 0.85, precision = 0.85), RF(accuracy = 0.71, precision = 0.71), GNB(accuracy = 0.75,precision = 0.65), MLP(accuracy = 0.88, precision = 0.9), BNB(accuracy = 0.75, precision = 0.69), and DT(accuracy = 0.85, precision = 0.76). In addition, the proposed model reduced the loss function to less than 0.3 and the RMSE and MSE to less than 0.2, which demonstrated a low error rate during processing.展开更多
The stability analysis of passive bolt-reinforced rock slopes under seismic loads is investigated within the framework of the kinematic approach of limit analysis theory.A pseudo-static method is adopted to account fo...The stability analysis of passive bolt-reinforced rock slopes under seismic loads is investigated within the framework of the kinematic approach of limit analysis theory.A pseudo-static method is adopted to account for the inertial forces induced in the rock mass by seismic events.The strength properties of the rock material are described by a modified Hoek-Brown strength criterion,whereas the passive bolts are modeled as bar-like inclusions that exhibit only resistance to tensile-compressive forces.Taking advantage of the ability to compute closed-form expressions for the support functions associated with the modified Hoek-Brown strength criterion,a rotational failure mechanism is implemented to derive rigorous lower bound estimates for the amount of reinforcement strength to prevent slope failure.The approach is then applied to investigating the effects of relevant geometry,strength and loading parameters in light of a preliminary parametric study.The accuracy of the approach is assessed by comparison of the lower bound estimates with finite element limit analysis solutions,thus emphasizing the ability of the approach to properly predict the stability conditions and to capture the essential features of deformation localization pattern.Finally,the extension of the approach to account for slipping at the interface between reinforcements and surrounding rock mass is outlined.展开更多
In order to investigate the effect of a weak intercalation on slope stability, a large-scale shaking table model test was conducted to study the dynamic response of rock slope models with weak intercalation.The dynami...In order to investigate the effect of a weak intercalation on slope stability, a large-scale shaking table model test was conducted to study the dynamic response of rock slope models with weak intercalation.The dynamic response of the prototype slopes were studied in laboratory with the consideration of law of similitude. The initiation failure was observed in the rock slope model with a counter-tilt thin-weak intercalation firstly, not in the slope model with a horizontal thin-weak intercalation. Furthermore, it was interesting that the fracture site is shifted from crest top to the slope surface near the weak intercalation, which is different with the location of failure position in a normal layered slope. We also discussed the effect of the dip angle and the thickness of weak intercalation on the failure mechanism and instability mode of the layered rock slope. From the experimental result, it was noted that the stability of the slope with a counter-tilt weak intercalation could be worse than that of the other slopes under seismic excitation. The findings showed the difference of failure in slopes with a horizontal and counter weak intercalation, and implicated the further evaluation of failure of layered slopes caused by seismic loads.展开更多
Ecological protection technique of rock slope is a new slope protection technique,and it is used widely in some supporting engineering of rock slope at railway and highway.But it is always an important research in the...Ecological protection technique of rock slope is a new slope protection technique,and it is used widely in some supporting engineering of rock slope at railway and highway.But it is always an important research in the field of geotechnical engineering,because the study is related to many subjects and is not systemic and idiographic enough.展开更多
Planar sliding is one of the frequently observed types of failure in rock slopes.Kinematic analysis is a classic and widely used method to examine the potential failure modes in rock masses.The accuracy of planar slid...Planar sliding is one of the frequently observed types of failure in rock slopes.Kinematic analysis is a classic and widely used method to examine the potential failure modes in rock masses.The accuracy of planar sliding kinematic analysis is significantly influenced by the value assigned to the lateral limit angleγlim.However,the assignment ofγlim is currently used generally based on an empirical criterion.This study aims to propose an approach for determining the value ofγlim in deterministic and probabilistic kinematic planar sliding analysis.A new perspective is presented to reveal thatγlim essentially influences the probability of forming a potential planar sliding block.The procedure to calculate this probability is introduced using the block theory method.It is found that the probability is correlated with the number of discontinuity sets presented in rock masses.Thus,different values ofγlim for rock masses with different sets of discontinuities are recommended in both probabilistic and deterministic planar sliding kinematic analyses;whereas a fixed value ofγlim is commonly assigned to different types of rock masses in traditional method.Finally,an engineering case was used to compare the proposed and traditional kinematic analysis methods.The error rates of the traditional method vary from 45%to 119%,while that of the proposed method ranges between 1%and 17%.Therefore,it is likely that the proposed method is superior to the traditional one.展开更多
基金financially supported by Youth Innovation Promotion Association,CAS(Grant No.2022333)Knowledge Innovation Program of Wuhan e Basic Research(Grant No.2022010801010161)Natural Science Foundation of Hubei Province,China(Grant No.2023AFD219).
文摘Block-flexure toppling constitutes the predominant form of toppling failure in rock slopes.Although it has been extensively studied,the current theoretical models are often oversimplified by treating rock layers as rigid bodies that diverge from actual conditions.The proposed Equivalent Deformation Compatibility Method(EDCM)offers a fresh approach to assess the stability of rock slopes prone to block-flexure toppling.EDCM posits that blocky rock layers,with their inability to withstand significant bending and role in merely transferring forces,can be modeled as intact layers with a reduced modulus.The method simplifies the complex issue of analyzing discrete and continuous rock layers to the study of layered soft and hard rock,establishing deformation compatibility equations subsequently.Validation of the EDCM was achieved through numerical models,physical model testing,and application to an actual slope.The factor of safety(FS)for slopes corresponds with the results from both models and the actual slope,demonstrating the method's applicability for evaluating susceptibility to block-flexure toppling.When applying the EDCM,it is advised to set the elastic modulus reduction coefficient for blocky layers at a value below 0.1.
基金supported by the National Natural Science Foundation of China(No.U23A2047,No.42277187,No.42307248)Natural Science Foundation of Hebei Province(No.D2022202005)。
文摘Rock slopes with large intersection angles between the strikes of strata and surface(RS-LISS)represent a unique type of layered rock slope.These slopes are usually considered to be well stabilized and less prone to landslides.However,when such slopes contain a significant number of discontinuities,their stability is greatly weakened.This study provided innovative insights into the stability of RS-LISS and conducted an in-depth investigation of their step-path failure mechanisms.The Riyi landslide on the eastern margin of the Qinghai-Tibet Plateau,China,was taken as a typical case and detailed investigations of geological structure and deformation characteristics of the slope were conducted by means of slope mapping,core drilling,and exploratory adits.A large number of steep-dip and gentle-dip joints were discovered in the slope,along with several critical discontinuities such as faults.Analysis shows that the tectonic stresses and river downcutting over geological time played significant roles in the formation of these discontinuities.Based on the investigation results,a numerical model of DFN for the Riyi landslide was developed.The simulation results indicated that the slope could develop a sliding surface characterized by a steep back and a gentle base,formed through the stepped interconnection of various discontinuities.Additionally,the deformation of the rock mass mainly originated from the major fault,progressively extending downward.The sliding mass may slide suddenly as a whole along the stepped bottom surface,with the compressional fracture zones as lateral boundaries,presenting a"drawer-like"movement towards the free surface.
基金supported by the National Natural Science Foundation of China(Grant Nos.42277161,42230709).
文摘Accurate identification and effective support of key blocks are crucial for ensuring the stability and safety of rock slopes.The number of structural planes and rock blocks were reduced in previous studies.This impairs the ability to characterize complex rock slopes accurately and inhibits the identification of key blocks.In this paper,a knowledge-data dually driven paradigm for accurate identification of key blocks in complex rock slopes is proposed.Our basic idea is to integrate key block theory into data-driven models based on finely characterizing structural features to identify key blocks in complex rock slopes accurately.The proposed novel paradigm consists of(1)representing rock slopes as graph-structured data based on complex systems theory,(2)identifying key nodes in the graph-structured data using graph deep learning,and(3)mapping the key nodes of graph-structured data to corresponding key blocks in the rock slope.Verification experiments and real-case applications are conducted by the proposed method.The verification results demonstrate excellent model performance,strong generalization capability,and effective classification results.Moreover,the real case application is conducted on the northern slope of the Yanqianshan Iron Mine.The results show that the proposed method can accurately identify key blocks in complex rock slopes,which can provide a decision-making basis and rational recommendations for effective support and instability prevention of rock slopes,thereby ensuring the stability of rock engineering and the safety of life and property.
基金We acknowledge the funding support from the National Key R&D Program of China(Grant No.2022YFC3080100)the National Natural Science Foundation of China(Grant No.42102316)the opening fund of State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University(Grant No.SKHL2306).
文摘The discrete fracture system of a rock mass plays a crucial role in controlling the stability of rock slopes.To fully account for the geometric shape and distribution characteristics of jointed rock masses,terrestrial laser scanning(TLS)was employed to acquire high-resolution point-cloud data,and a developed automatic discontinuity-identification technology was coupled to automatically interpret and characterize geometric information such as orientation,trace length,spacing,and set number of the discontinuities.The discrete element method(DEM)was applied to study the influence of the geometric morphology and distribution characteristics of discontinuities on slope stability by generating a discrete fracture network(DFN)with the same statistical characteristics as the actual discontinuities.Based on slope data from the Yebatan Hydropower Station,a simulation was conducted to verify the applicability of the automatic discontinuity identification technology and the discrete fracture network-discrete element method(DFN-DEM).Various geological parameters,including trace length,persistence,and density,were examined to investigate the morphological evolution and response characteristics of rock slope excavation under different joint combination conditions through simulation.The simulation results indicate that joint parameters affect slope stability,with density having the most significant impact.The impact of joint parameters on stability is relatively small within a reasonable range but becomes significant beyond a certain threshold,further validating that the accuracy of field geological surveys is critical for simulation.This study provides a scientific basis for the construction of complex rock slope models,engineering assessments,and disaster prevention and mitigation,which is of great value in both theory and engineering applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.52274075,42122052,52379098)。
文摘Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain poorly understood.In this study,finite element method-based numerical simulations were conducted based on the rock slope at Dagangshan Hydropower Station in Sichuan province,China.Firstly,systematic analysis in both the time and frequency domains were performed to examine the seismic dynamic characteristics of the slope.Subsequently,the transfer function method and the multiple stepwise linear regression method were employed to clarify the underlying mechanism and determine critical factors influencing the slope instability during earthquakes.Time-domain analysis reveals that rock slope dynamic response exhibits notable elevation,surface,and local amplification effects.Specifically,the Peak Ground Acceleration(PGA)amplification coefficient(MPGA)is significantly higher at elevated locations,near the slope surface and in areas with protrusions.Moreover,the existence of fracture zones and anti-shear galleries minimally influences the dynamic responses but considerably affect the rupture.Specifically,fracture zones exacerbate rupture,while anti-shear galleries mitigate it.Frequency-domain analysis indicates that the dynamic responses of the slope are closely correlated with the degree of slope rupture.As earthquake magnitude increases,the rupture degree of the slope intensifies,and the dominant frequency of the response within the slope decreases,e.g.,its value shifts from 3.63 to 2.75 Hz at measurement point 9near the slope surface.The transfer function of rock slope,calculated under the excitation of wide flat spectrum white noise can reflect the interrelationships between the inherent properties and the rupture degree.Notably,the peak of the transfer function undergoes inversion as the degree of rupture increases.Furthermore,through multiple stepwise linear regression analysis,four key factors influencing the surface dynamic response of the slope were identified:rock strength,slope angle,elevation,and seismic dominant frequency.These findings provide valuable insights into the underlying mechanisms of rock slope dynamic responses triggered by earthquakes,offering essential guidance for understanding and mitigating seismic impacts on rock slopes.
基金funding support from the National Natural Science Foundation of China(Grant No.42072303)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(Grant No.SKLGP2021Z004).
文摘Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects as static loads often underestimates rock slope stability.The development of a practical stability analysis approach for ABRSs,particularly in slope engineering design,is imperative.This study proposes a stability evaluation model for ABRSs,incorporating the viscoelastic properties of rock,to quantitatively assess the safety factor and failure surface under seismic conditions.The mathematical description of the pseudo-dynamic method,derived in this study,accounts for the viscoelastic properties of ABRSs and integrates the HoekeBrown failure criterion with the Kelvin-Voigt stress-strain relationship of rocks.Furthermore,to address concurrent translation-rotation failure in ABRSs,upper bound limit analysis is utilized to quantify the safety factor.Through a comparison with existing literature,the proposed method considers the effect of harmonic vibration on the stability of ABRSs.The obtained safety factor is lower than that of the quasi-static method,with the resulting percentage change exceeding 5%.The critical failure surface demonstrates superior positional accuracy compared to the Aydan and Adhikary basal planes,with minimal error observed between the physical model test and the numerical simulation test.The parameter sensitivity analysis reveals that the inclination of ABRSs exhibits the highest sensitivity(Sk)value across the three levels of horizontal seismic coefficient(kh).The study aims to devise an expeditious calculation approach for assessing the stability of ABRSs during seismic events,intending to offer theoretical guidance for their stability analysis.
基金supported by National Natural Science Foundation of China(Grant No.12072358)Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2022333)Key Laboratory of Roads and Railway Safety Control(Shijiazhuang Tiedao University),the Ministry of Education(Grant No.STDTKF202103).
文摘Rock slopes are usually reinforced by a number of rock bolts due to the high efficiency and low price.However,where should the rock bolts be installed is still a troublesome issue.For anti-dip bedding rock slopes(ABRSs),the installation position of rock bolts is a controlling factor that determines the reinforcement effect.In this work,a theoretical method is firstly proposed for assessing the stability of ABRSs reinforced by rock bolts using a limit equilibrium model.A comparison of theoretical calculations and numerical results was conducted to test the correctness of the theoretical method.Based on the stability assessment of ABRSs,we introduce adaptive moment estimation method(Adam)to optimize the installation location of rock bolts.Using Adam optimizer,the optimal layout of rock bolts with the maximum factor of safety can be determined,and the factor of safety of the slope increases by about 25%using the same amount of rock bolts but with different installation locations.The proposed method enables the fast stability analysis and supporting design for reinforced ABRSs,which paves the way to smart supporting design of slopes.
基金the China Postdoctoral Science Foundation(Grant No.2023M730432)the Special Funding for Chongqing Postdoctoral Research Project(Grant No.2022CQBSHTB1010)the Chongqing Postdoctoral Science Foundation(Grant No.CSTB2023NSCQ-BHX0223).
文摘Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads.Three models of typical bedded rock slopes(BRSs),i.e.gently(GIS),moderately(MIS),and steeply(SIS)inclined slopes,were proposed according to field investigations.The dynamic response mechanism and stability of the BRSs,affected by the rock mass deterioration of the HFB,were investigated by the shaking table test and the universal distinct element code(UDEC)simulation.Specifically,the amplification coefficient of the peak ground acceleration(PGA)of the slope was gradually attenuated under multiple seismic loads,and the acceleration response showed obvious“surface effect”and“elevation effect”in the horizontal and vertical directions,respectively.The“S-type”cubic function and“steep-rise type”exponential function were used to characterize the cumulative damage evolution of the slope caused by microseismic waves(low seismic waves)and high seismic waves,respectively.According to the dynamic responses of the acceleration,cumulative displacement,rock pressure,pore water pressure,damping ratio,natural frequency,stability coefficient,and sliding velocity of the slope,the typical evolution processes of the dynamic cumulative damage and instability failure of the slope were generalized,and the numerical and experimental results were compared.Considering the dynamic effects of the slope height(SH),slope angle(SA),bedding plane thickness(BPT),dip angle of the bedding plane(DABP),dynamic load amplitude(DLA),dynamic load frequency(DLF),height of water level of the hydro-fluctuation belt(HWLHFB),degradation range of the hydro-fluctuation belt(DRHFB),and degradation shape of the hydro-fluctuation belt(DSHFB),the sensitivity of factors influencing the slope dynamic stability using the orthogonal analysis method(OAM)was DLA>DRHFB>SA>SH>DLF>HWLHFB>DSHFB>DABP>BPT.
基金supported by the National Natural Science Foundation of China(Nos.52208369,52309138,52209142,51978666)the Department of Science and Technology of Sichuan Province(2023NSFSC0284).
文摘In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.
基金funded by the National Natural Science Foundation of China (Grant No. 41825018)the National Key Research and Development Plan of China (Grant No. 2019YFC1509704)the Second Tibetan Plateau Scientific Expedition and Research Program (STEP, Grant No. 2019QZKK0904)。
文摘Bedding rock slopes are common geological features in nature that are prone to failure under strong earthquakes. Their failures induce catastrophic landslides and form barrier lakes, posing severe threats to people’s lives and property. Based on the similarity criteria, a bedding rock slope model with a length of3 m, a width of 0.8 m, and a height of 1.6 m was constructed to facilitate large-scale shaking table tests.The results showed that with the increase of vibration time, the natural frequency of the model slope decreased, but the damping ratio increased. Damage to the rock mass structure altered the dynamic characteristics of the slope;therefore, amplification of the acceleration was found to be nonlinear and uneven. Furthermore, the acceleration was amplified nonlinearly with the increase of slope elevation along the slope surface and the vertical section, and the maximum acceleration amplification factor(AAF) occurred at the slope crest. Before visible deformation, the AAF increased with increasing shaking intensity;however, it decreased with increasing shaking intensity after obvious deformation. The slope was likely to slide along the bedding planes at a shallow depth below the slope surface. The upper part of the slope mainly experienced a tensile-shear effect, whereas the lower part suffered a compressive-shear force. The progressive failure process of the model slope can be divided into four stages, and the dislocated rock mass can be summarized into three zones. The testing data provide a good explanation of the dynamic behavior of the rock slope when subjected to an earthquake and may serve as a helpful reference in implementing antiseismic measures for earthquake-induced landslides.
基金the Research Fund of National Natural Science Foundation of China(NSFC)(No.42277154)the project supported by graduate research and innovation foundation of Chongqing,China(No.CYB22023)+3 种基金Guizhou Province Science and Technology Planning Project(No.Guizhou science and technology cooperation support[2022]common 229)National Natural Science Foundation of Shandong Province of China(NSFC)(No.ZR2022ME188)the State Key Laboratory of Coal Resources and Safe Mining,CUMT(No.SKLCRSM22KF009)Open Fund of National Engineering and Technology Research Center for Development and Utilization of Phosphate Resources of China(No.NECP 2022-04).
文摘Two critical factors,namely intense precipitation and intricate excavation,can trigger rock mass disasters in mining operations.In this study,an indoor rainfall system was developed to precisely regulate the flow and intensity of precipitation.A large-scale model experiment was conducted on a self-designed physical simulation experiment platform to investigate the failure and instability of high-steep rock slopes under unsaturated conditions.The real-time reproduction of the progressive failure process in high-steep rock slopes enabled the determination of the critical rainfall intensity and revealed the mechanism underlying slope instability.Experiment results indicated that rainfall may be the primary factor contributing to rock mass instability,while continuous pillar mining exacerbates the extent of rock mass failure.The critical failure stage of high-steep rock slopes occurs at a rainfall intensity of 40 mm/h,whereas a rainfall exceeding 50 mm can induce critical instability and precipitation reaching up to 60 mm will result in slope failure.The improved region growing segmentation method(IRGSM)was subsequently employed for image recognition of rock mass deformation in underground mines.Herein an error comparison with the simple linear iterative cluster(SLIC)superpixel method and the original region growing segmentation method(ORGSM)showed that the average identification error in the X and Y directions by the method was reduced significantly(1.82%and 1.80%in IRGSM;4.70%and 6.26%in SLIC;9.45%and 12.40%in ORGSM).Ultimately,the relationship between rainfall intensity and failure probability was analyzed using the Monte Carlo method.Moreover,the stability assessment criteria of rock slope under unsaturated condition were quantitatively and accurately evaluated.
基金supported by grants from the National Basic Research Program of China (Grant Nos. 2011CB013503, 2014CB047103)the National Natural Science Foundation of China (Grant Nos. 51279024, 51209127)
文摘For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of water level in the service lifetime of slopes. According to the concept that the progressivedamage （microseismicity） of rock slope is the essence of the precursor of slope instability, a microseismicmonitoring system for high-steep rock slopes is established. Positioning accuracy of the monitoringsystem is tested by fixed-position blasting method. Based on waveform and cluster analyses of microseismicevents recorded during test, the tempo-spatial distribution of microseismic events is analyzed.The deformation zone in the deep rock masses induced by the microseismic events is preliminarilydelimited. Based on the physical information measured by in situ microseismic monitoring, an evaluationmethod for the dynamic stability of rock slopes is proposed and preliminarily implemented bycombining microseismic monitoring and numerical modeling. Based on the rock mass damage modelobtained by back analysis of microseismic information, the rock mass elements within the microseismicdamage zone are automatically searched by finite element program. Then the stiffness and strengthreductions are performed on these damaged elements accordingly. Attempts are made to establish thecorrelation between microseismic event, strength deterioration and slope dynamic instability, so as toquantitatively evaluate the dynamic stability of slope. The case studies about two practical slopes indicatethat the proposed method can reflect the factor of safety of rock slope more objectively. Numericalanalysis can help to understand the characteristics and modes of the monitored microseismic events inrock slopes. Microseismic monitoring data and simulation results can be used to mutually modify thesensitive rock parameters and calibrate the model. Combination of microseismic monitoring and numericalsimulation provides a more objective basis for the numerical model and parameters and a solidmechanical foundation for the microseismic monitoring.
基金Project(51978666) supported by the National Natural Science Foundation of ChinaProject(2018-123-040) supported by the Guizhou Provincial Department of Transportation Foundation, ChinaProject(2019zzts009) supported by the Fundamental Research Funds for the Central Universities, China。
文摘Several potential failure modes generally exist in rock slopes because of the existence of massive structural planes in rock masses. A system reliability analyses method for rock slopes with multiple failure modes based on nonlinear Barton-Bandis failure criterion is proposed. The factors of safety associated with the sliding and overturning failure modes are derived, respectively. The validity of this method is verified through a planar rock slope with an inclined slope top and tension crack. Several sensitivity analyses are adopted to study the influences of structural-plane parameters, geometric parameters, anchoring parameters and fracture morphology on the rock slopes system reliability.
基金National Basic Research Program of China under Grant No.2015CB057902Beijing Municipal Natural Science Foundation under Grant No.8164049Young Foundation of the National Science of China under Grant No.51608015
文摘Seismic stability of slopes has been traditionally analyzed with vertically propagated earthquake waves.However,for rock slopes,the earthquake waves might approach the outcrop still with a evidently oblique direction.To investigate the impact of obliquely incident earthquake excitations,the input method for SV and P waves with arbitrary incident angles is conducted,respectively,by adopting the equivalent nodal force method together with a viscous-spring boundary.Then,the input method is introduced within the framework of ABAQUS software and verified by a numerical example.Both SV and P waves input are considered herein for a 2 D jointed rock slope.For the jointed rock mass,the jointed material model in ABAQUS software is employed to simulate its behavior as a continuum.Results of the study show that the earthquake incident angles have significance on the seismic stability of jointed rock slopes.The larger the incident angle,the greater the risk of slope instability.Furthermore,the stability of the jointed rock slopes also is affected by wave types of earthquakes heavily.P waves induce weaker responses and SV waves are shown to be more critical.
基金supported by the Natural Science Foundation of China(Grant No.51939004)the Fundamental Research Funds for the Central Universities(Grant No.B210204009)the China Huaneng Group Science and Technology Project(Grant No.HNKJ18-H24).
文摘Safety evaluation of toppling rock slopes developing in reservoir areas is crucial. To reduce the uncertainty of safety evaluation, this study developed a composite cloud model, which improved the combination weights of the decision-making trial and evaluation laboratory (DEMATEL) and criteria importance through intercriteria correlation (CRITIC) methods. A safety evaluation system was developed according to in situ monitoring data. The backward cloud generator was used to calculate the numerical characteristics of a cloud model of quantitative indices, and different virtual clouds were used to synthesize some clouds into a generalized one. The synthesized numerical characteristics were calculated to comprehensively evaluate the safety of toppling rock slopes. A case study of a toppling rock slope near the Huangdeng Hydropower Station in China was conducted using monitoring data collected since operation of the hydropower project began. The results indicated that the toppling rock slope was moderately safe with a low safety margin. The composite cloud model considers the fuzziness and randomness of safety evaluation and enables interchange between qualitative and quantitative knowledge. This study provides a new theoretical method for evaluating the safety of toppling rock slopes. It can aid in the predication, control, and even prevention of disasters.
基金support provided by the National Natural Science Foundation of China(Grant No.42077235)the National Key Research and Development Program of China(Grant No.2018YFC1505104).
文摘The key-blocks are the main reason accounting for structural failure in discontinuous rock slopes, and automated identification of these block types is critical for evaluating the stability conditions. This paper presents a classification framework to categorize rock blocks based on the principles of block theory. The deep convolutional neural network(CNN) procedure was utilized to analyze a total of 1240 highresolution images from 130 slope masses at the South Pars Special Zone, Assalouyeh, Southwest Iran.Based on Goodman’s theory, a recognition system has been implemented to classify three types of rock blocks, namely, key blocks, trapped blocks, and stable blocks. The proposed prediction model has been validated with the loss function, root mean square error(RMSE), and mean square error(MSE). As a justification of the model, the support vector machine(SVM), random forest(RF), Gaussian naïve Bayes(GNB), multilayer perceptron(MLP), Bernoulli naïve Bayes(BNB), and decision tree(DT) classifiers have been used to evaluate the accuracy, precision, recall, F1-score, and confusion matrix. Accuracy and precision of the proposed model are 0.95 and 0.93, respectively, in comparison with SVM(accuracy = 0.85, precision = 0.85), RF(accuracy = 0.71, precision = 0.71), GNB(accuracy = 0.75,precision = 0.65), MLP(accuracy = 0.88, precision = 0.9), BNB(accuracy = 0.75, precision = 0.69), and DT(accuracy = 0.85, precision = 0.76). In addition, the proposed model reduced the loss function to less than 0.3 and the RMSE and MSE to less than 0.2, which demonstrated a low error rate during processing.
基金financial support from Ecole des Ponts et Chaussées-ParisTech(France)the French Institute of Tunisia (French Embassy-Tunisia)Laboratoire de Génie Civil (ENIT) through project SSHN2015-ENPC/ENIT
文摘The stability analysis of passive bolt-reinforced rock slopes under seismic loads is investigated within the framework of the kinematic approach of limit analysis theory.A pseudo-static method is adopted to account for the inertial forces induced in the rock mass by seismic events.The strength properties of the rock material are described by a modified Hoek-Brown strength criterion,whereas the passive bolts are modeled as bar-like inclusions that exhibit only resistance to tensile-compressive forces.Taking advantage of the ability to compute closed-form expressions for the support functions associated with the modified Hoek-Brown strength criterion,a rotational failure mechanism is implemented to derive rigorous lower bound estimates for the amount of reinforcement strength to prevent slope failure.The approach is then applied to investigating the effects of relevant geometry,strength and loading parameters in light of a preliminary parametric study.The accuracy of the approach is assessed by comparison of the lower bound estimates with finite element limit analysis solutions,thus emphasizing the ability of the approach to properly predict the stability conditions and to capture the essential features of deformation localization pattern.Finally,the extension of the approach to account for slipping at the interface between reinforcements and surrounding rock mass is outlined.
基金financially supported by the Research and Innovation Team of Chengdu University of TechnologyProject of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Grant No. SKLGP2013Z002)
文摘In order to investigate the effect of a weak intercalation on slope stability, a large-scale shaking table model test was conducted to study the dynamic response of rock slope models with weak intercalation.The dynamic response of the prototype slopes were studied in laboratory with the consideration of law of similitude. The initiation failure was observed in the rock slope model with a counter-tilt thin-weak intercalation firstly, not in the slope model with a horizontal thin-weak intercalation. Furthermore, it was interesting that the fracture site is shifted from crest top to the slope surface near the weak intercalation, which is different with the location of failure position in a normal layered slope. We also discussed the effect of the dip angle and the thickness of weak intercalation on the failure mechanism and instability mode of the layered rock slope. From the experimental result, it was noted that the stability of the slope with a counter-tilt weak intercalation could be worse than that of the other slopes under seismic excitation. The findings showed the difference of failure in slopes with a horizontal and counter weak intercalation, and implicated the further evaluation of failure of layered slopes caused by seismic loads.
文摘Ecological protection technique of rock slope is a new slope protection technique,and it is used widely in some supporting engineering of rock slope at railway and highway.But it is always an important research in the field of geotechnical engineering,because the study is related to many subjects and is not systemic and idiographic enough.
基金funded by National Natural Science Foundation,China(Grant Nos.41972264 and 42207214)Zhejiang Provincial Natural Science Foundation,China(Grant No.LR22E080002).
文摘Planar sliding is one of the frequently observed types of failure in rock slopes.Kinematic analysis is a classic and widely used method to examine the potential failure modes in rock masses.The accuracy of planar sliding kinematic analysis is significantly influenced by the value assigned to the lateral limit angleγlim.However,the assignment ofγlim is currently used generally based on an empirical criterion.This study aims to propose an approach for determining the value ofγlim in deterministic and probabilistic kinematic planar sliding analysis.A new perspective is presented to reveal thatγlim essentially influences the probability of forming a potential planar sliding block.The procedure to calculate this probability is introduced using the block theory method.It is found that the probability is correlated with the number of discontinuity sets presented in rock masses.Thus,different values ofγlim for rock masses with different sets of discontinuities are recommended in both probabilistic and deterministic planar sliding kinematic analyses;whereas a fixed value ofγlim is commonly assigned to different types of rock masses in traditional method.Finally,an engineering case was used to compare the proposed and traditional kinematic analysis methods.The error rates of the traditional method vary from 45%to 119%,while that of the proposed method ranges between 1%and 17%.Therefore,it is likely that the proposed method is superior to the traditional one.
