This study presents a novel method to evaluate the safety of open-pit slopes by means of three-dimensional numerical modeling with the finite difference method. The method presented here uses a block model as a vehicl...This study presents a novel method to evaluate the safety of open-pit slopes by means of three-dimensional numerical modeling with the finite difference method. The method presented here uses a block model as a vehicle to carry relevant information from the rock mass and automatically construct the numerical model. The results suggest that the method is promising because of its capacity to accurately incorporate a large amount of high-complexity rock data by considering spatial location and material behavior. It is expected that the innovations in this method will make the design, construction, and operation of open-pit iron mines safer and more economical.展开更多
Collapses of seismic slopes demonstrate the characteristics of three-dimensional(3D)shapes.Conducting a 3D analysis of seismic slope stability is more complicated than doing a simplified two-dimensional(2D)analysis.Th...Collapses of seismic slopes demonstrate the characteristics of three-dimensional(3D)shapes.Conducting a 3D analysis of seismic slope stability is more complicated than doing a simplified two-dimensional(2D)analysis.The upper-bound solutions derived from limit analysis of seismic slopes using the pseudo-static method are used to generate an approximate solution for the factor of 3D safety through regression analysis.Such a solution can degenerate to a 2D result when the slope width tends to infinity.The approximation method also can be extended for determining the permanent displacements of 3D slopes under seismic loading.The method is non-iterative and relatively accurate through comparisons with analytical results.Involving stochastic ground motions could easily be used to assess the distribution of permanent displacement that is induced in 3D slopes.展开更多
This paper presents probabilistic assessment of seismically-induced slope displacements considering uncertainties of seismic ground motions and soil properties.A stochastic ground motion model representing both the te...This paper presents probabilistic assessment of seismically-induced slope displacements considering uncertainties of seismic ground motions and soil properties.A stochastic ground motion model representing both the temporal and spectral non-stationarity of earthquake shakings and a three-dimensional rotational failure mechanism are integrated to assess Newmark-type slope displacements.A new probabilistic approach that incorporates machine learning in metamodeling technique is proposed,by combining relevance vector machine with polynomial chaos expansions(RVM-PCE).Compared with other PCE methods,the proposed RVM-PCE is shown to be more effective in estimating failure probabilities.The sensitivity and relative influence of each random input parameter to the slope displacements are discussed.Finally,the fragility curves for slope displacements are established for sitespecific soil conditions and earthquake hazard levels.The results indicate that the slope displacement is more sensitive to the intensities and strong shaking durations of seismic ground motions than the frequency contents,and a critical Arias intensity that leads to the maximum annual failure probabilities can be identified by the proposed approach.展开更多
The influences of soil dilatancy angle on three-dimensional （3D） seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-...The influences of soil dilatancy angle on three-dimensional （3D） seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-static coefficient concept. Extended Bishop method and Boussinesq theorem were employed to establish the stress distribution along the rupture surfaces that are required to obtain the rate of internal energy dissipation for the nonassociated flow rule materials in rotational collapse mechanisms. Good agreement was observed by comparing the current results with those obtained using the translational or rotational mechanisms and numerical finite difference method. The results indicate that the seismic stability of slopes reduces by decreasing the dilatancy angle for nonassociated flow rule materials. The amount of the mentioned decrease is more significant in the case of mild slopes in frictional soils. A nearly infinite slope under local loading, whether its critical failure surface is 2D or 3D, not only depends on the magnitude of the external load, but also depends on the dilataney angle of soil and the coefficient of seismic load.展开更多
Even Unzen volcano has been declared to be in a state of relative dormancy,the latest formed lava lobe No.11 now represents a potential slope failure mass based on the latest research.This paper concentrates on the st...Even Unzen volcano has been declared to be in a state of relative dormancy,the latest formed lava lobe No.11 now represents a potential slope failure mass based on the latest research.This paper concentrates on the stability of the lava lobe No.11 and its possible critical sliding mass.It proposes geographic information systems (GIS) based three-dimensional (3D) slope stability analysis models.It uses a 3D locating approach to identify the 3D critical slip surface and to analyze the 3D stability of the lava lobe No.11.At the same time,the new 3D approach shows the effectiveness in selecting the range of the Monte Carlo random variables and locating the critical slip surface in different parts of the lava lobe No.11.The results are very valuable for judging the stability of the lava lobe and assigning the monitoring equipments.展开更多
The effects of ternary solutes Ti, Co, V, Cr, Ta, W and Mo on the D03 phase 5tability of Fe3Alintermetallics are investigated by tight-binding linear Muffin-tin orbitaI method. The predictedsite preference5 of these e...The effects of ternary solutes Ti, Co, V, Cr, Ta, W and Mo on the D03 phase 5tability of Fe3Alintermetallics are investigated by tight-binding linear Muffin-tin orbitaI method. The predictedsite preference5 of these elements in Fe3AI are in agreement with the experimental observations.The calculated Iocal magnetic moment of Fe3AI is identical to the experimentaI. ln addition, itis found that the D03 phase stability of Fe3AI doped with Ti, V, Co and Cr depends on 'energygap- of energy band near Fermi level. while the D03 phase stability of Fe3AI doped with Ta, Wand Mo may be affected by Madelung energy.展开更多
A physically-based numerical three-dimensional earthen dam piping failure model is developed for homogeneous and zoned soil dams.This model is an erosion model,coupled with force/moment equilibrium analyses.Orifice fl...A physically-based numerical three-dimensional earthen dam piping failure model is developed for homogeneous and zoned soil dams.This model is an erosion model,coupled with force/moment equilibrium analyses.Orifice flow and two-dimensional(2D)shallow water equations(SWE)are solved to simulate dam break flows at different breaching stages.Erosion rates of different soils with different construction compaction efforts are calculated using corresponding erosion formulae.The dam's real shape,soil properties,and surrounding area are programmed.Large outer 2D-SWE grids are used to control upstream and downstream hydraulic conditions and control the boundary conditions of orifice flow,and inner 2D-SWE flow is used to scour soil and perform force/moment equilibrium analyses.This model is validated using the European Commission IMPACT(Investigation of Extreme Flood Processes and Uncertainty)Test#5 in Norway,Teton Dam failure in Idaho,USA,and Quail Creek Dike failure in Utah,USA.All calculated peak outflows are within 10%errors of observed values.Simulation results show that,for a V-shaped dam like Teton Dam,a piping breach location at the abutment tends to result in a smaller peak breach outflow than the piping breach location at the dam's center;and if Teton Dam had broken from its center for internal erosion,a peak outflow of 117851 m'/s,which is 81%larger than the peak outflow of 65120 m3/s released from its right abutment,would have been released from Teton Dam.A lower piping inlet elevation tends to cause a faster/earlier piping breach than a higher piping inlet elevation.展开更多
文摘This study presents a novel method to evaluate the safety of open-pit slopes by means of three-dimensional numerical modeling with the finite difference method. The method presented here uses a block model as a vehicle to carry relevant information from the rock mass and automatically construct the numerical model. The results suggest that the method is promising because of its capacity to accurately incorporate a large amount of high-complexity rock data by considering spatial location and material behavior. It is expected that the innovations in this method will make the design, construction, and operation of open-pit iron mines safer and more economical.
基金National Natural Science Foundation of China under Grant No.52322808the Fundamental Research Funds for the Central Universities under Grant No.B220202013。
文摘Collapses of seismic slopes demonstrate the characteristics of three-dimensional(3D)shapes.Conducting a 3D analysis of seismic slope stability is more complicated than doing a simplified two-dimensional(2D)analysis.The upper-bound solutions derived from limit analysis of seismic slopes using the pseudo-static method are used to generate an approximate solution for the factor of 3D safety through regression analysis.Such a solution can degenerate to a 2D result when the slope width tends to infinity.The approximation method also can be extended for determining the permanent displacements of 3D slopes under seismic loading.The method is non-iterative and relatively accurate through comparisons with analytical results.Involving stochastic ground motions could easily be used to assess the distribution of permanent displacement that is induced in 3D slopes.
基金financially supported by the Research Grants Council of the Hong Kong Special Administrative Region(Project No.15212418)。
文摘This paper presents probabilistic assessment of seismically-induced slope displacements considering uncertainties of seismic ground motions and soil properties.A stochastic ground motion model representing both the temporal and spectral non-stationarity of earthquake shakings and a three-dimensional rotational failure mechanism are integrated to assess Newmark-type slope displacements.A new probabilistic approach that incorporates machine learning in metamodeling technique is proposed,by combining relevance vector machine with polynomial chaos expansions(RVM-PCE).Compared with other PCE methods,the proposed RVM-PCE is shown to be more effective in estimating failure probabilities.The sensitivity and relative influence of each random input parameter to the slope displacements are discussed.Finally,the fragility curves for slope displacements are established for sitespecific soil conditions and earthquake hazard levels.The results indicate that the slope displacement is more sensitive to the intensities and strong shaking durations of seismic ground motions than the frequency contents,and a critical Arias intensity that leads to the maximum annual failure probabilities can be identified by the proposed approach.
文摘The influences of soil dilatancy angle on three-dimensional （3D） seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-static coefficient concept. Extended Bishop method and Boussinesq theorem were employed to establish the stress distribution along the rupture surfaces that are required to obtain the rate of internal energy dissipation for the nonassociated flow rule materials in rotational collapse mechanisms. Good agreement was observed by comparing the current results with those obtained using the translational or rotational mechanisms and numerical finite difference method. The results indicate that the seismic stability of slopes reduces by decreasing the dilatancy angle for nonassociated flow rule materials. The amount of the mentioned decrease is more significant in the case of mild slopes in frictional soils. A nearly infinite slope under local loading, whether its critical failure surface is 2D or 3D, not only depends on the magnitude of the external load, but also depends on the dilataney angle of soil and the coefficient of seismic load.
基金Supported by the National Natural Science Foundation of China (40972229)provided by JSPS and Sabo Technical Center,Japan
文摘Even Unzen volcano has been declared to be in a state of relative dormancy,the latest formed lava lobe No.11 now represents a potential slope failure mass based on the latest research.This paper concentrates on the stability of the lava lobe No.11 and its possible critical sliding mass.It proposes geographic information systems (GIS) based three-dimensional (3D) slope stability analysis models.It uses a 3D locating approach to identify the 3D critical slip surface and to analyze the 3D stability of the lava lobe No.11.At the same time,the new 3D approach shows the effectiveness in selecting the range of the Monte Carlo random variables and locating the critical slip surface in different parts of the lava lobe No.11.The results are very valuable for judging the stability of the lava lobe and assigning the monitoring equipments.
文摘The effects of ternary solutes Ti, Co, V, Cr, Ta, W and Mo on the D03 phase 5tability of Fe3Alintermetallics are investigated by tight-binding linear Muffin-tin orbitaI method. The predictedsite preference5 of these elements in Fe3AI are in agreement with the experimental observations.The calculated Iocal magnetic moment of Fe3AI is identical to the experimentaI. ln addition, itis found that the D03 phase stability of Fe3AI doped with Ti, V, Co and Cr depends on 'energygap- of energy band near Fermi level. while the D03 phase stability of Fe3AI doped with Ta, Wand Mo may be affected by Madelung energy.
文摘A physically-based numerical three-dimensional earthen dam piping failure model is developed for homogeneous and zoned soil dams.This model is an erosion model,coupled with force/moment equilibrium analyses.Orifice flow and two-dimensional(2D)shallow water equations(SWE)are solved to simulate dam break flows at different breaching stages.Erosion rates of different soils with different construction compaction efforts are calculated using corresponding erosion formulae.The dam's real shape,soil properties,and surrounding area are programmed.Large outer 2D-SWE grids are used to control upstream and downstream hydraulic conditions and control the boundary conditions of orifice flow,and inner 2D-SWE flow is used to scour soil and perform force/moment equilibrium analyses.This model is validated using the European Commission IMPACT(Investigation of Extreme Flood Processes and Uncertainty)Test#5 in Norway,Teton Dam failure in Idaho,USA,and Quail Creek Dike failure in Utah,USA.All calculated peak outflows are within 10%errors of observed values.Simulation results show that,for a V-shaped dam like Teton Dam,a piping breach location at the abutment tends to result in a smaller peak breach outflow than the piping breach location at the dam's center;and if Teton Dam had broken from its center for internal erosion,a peak outflow of 117851 m'/s,which is 81%larger than the peak outflow of 65120 m3/s released from its right abutment,would have been released from Teton Dam.A lower piping inlet elevation tends to cause a faster/earlier piping breach than a higher piping inlet elevation.
