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Scale problem:Influence of grid spacing of digital elevation model on computed Slope and shielded extra-terrestrial solar radiation

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Frontiers of Earth Science 2020年第1期14卷 171-187页

作者： Nan CHEN Key Laboratory of Spatial Data Mining&Information Sharing(Ministry of Education) Fuzhou UniversityFuzhou 350108 China Spatial Information Research Center of Fujian Province Fuzhou UniversityFuzhou 350108 China

Solar radiation is the primary energy source that drives many of Earth’s physical and biological processes and determines the patterns of climate and productivity on the surface of the Earth.A fundamental proportion of solar radiation is composed of shielded extraterrestrial solar radiation(SESR),which can be computed using the Slope and aspect derived from a digital elevation model(DEM).The objective of this paper is to determine the influence of the grid spacing of the DEM(the influence of the scale of the DEM)on the errors of Slope,aspect and SESR.This paper puts forward the concepts of Slope representation error,aspect representation error,and SESR representation error and then studies the relations among these errors and the grid spacing of DEMs.We find that when the grid spacing of a DEM becomes coarser,the average SESR increases;the increase in SESR is dominated by the grid cells of the DEM with a negative Slope representation error,whereas SESR generally decreases in the grid cells with a positive Slope representation error.Although the grid spacing varies,the distribution of the percentages of positive SESR representation errors on the Slope,which is classified into 11 Slope intervals,is independent of the grid spacing;this distribution is concentrated across some Slope intervals.Moreover,the average absolute value and mean square error of the SESR representation error are closely related to those of the Slope representation error and the aspect representation error.The findings in this study may be useful for predicting and reducing the errors in SESR measurements and may help to avoid mistakes in foture research and in practical applications in which SESR is the data of interest or plays a vital role in an analysis.

关键词： scale problem digital elevation model grid spacing Slope shielded extra-terrestrial solar radiation

Probabilistic approach for open pit bench Slope stability analysis——A mine case study

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International Journal of Mining Science and Technology 2019年第4期29卷 629-640页

作者： Christian Obregon Hani Mitri Department of Mining and Materials Engineering McGill University

The geotechnical Slope design of an open pit wall starts at the bench scale configuration.At this scale,the rock Slope stability is governed primarily by the geological discontinuities within the rock mass and as a result,structurally-controlled failures(e.***.planar,wedge or toppling)are most likely to occur.The probabilistic approach offers a major advantage over the traditional deterministic method in that it accounts for the different degrees of variability and uncertainty often encountered in rock properties.This paper presents a bench Slope stability assessment for an open pit mine in Peru using a probabilistic-based approach by coupling a kinematic analysis based on stereographic projection techniques followed by a kinetic analysis by means of the limit equilibrium method.Finally,these two probabilities are combined to provide an overall measure of the probability of failure(PoF)of the bench Slope system.The case study is characterized by significant scatter in the geometrical and mechanical properties of the joints.Extensive surface mapping was conducted at 36 different sites following the ISRM suggested procedures.Several direct shear tests were carried out.It is shown that by combining field and laboratory measurements and engineering judgment,the probability density functions(PDF)of the discontinuity parameters can be obtained.These are then used in a Monte Carlo simulation process to compute both kinematic and kinetic probabilities of failure.The overall probability of failure aims to provide the design engineer with a tool to critically evaluate the bench performance from a geotechnical risk perspective and to provide a basis for future bench design optimization.

关键词： Mine safety Rock Slope stability Kinematic analysis Probability of failure Limit equilibrium analysis Case study

Methods applied in Australian industry to evaluate coal mine Slope stability

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International Journal of Mining Science and Technology 2020年第2期30卷 151-155页

作者： Alison McQuillan Ismet Canbulat Joung Oh School of Minerals and Energy Resources Engineering UNSW SydneyAustralia

Strata failure is a principal hazard in open cut coal mining as it has the potential to cause multiple fatalities.Prior to the excavation of any Slope,a geotechnical assessment should review the likely Slope performance,including the risk of Slope failure.Controls to manage this risk to an acceptable level should accompany the geotechnical analysis.A survey of 43 practising geotechnical engineers indicated that kinematic and 2D limit equilibrium analyses were the methods most commonly applied to analyse excavated Slope stability.While these methods are well established and widely applied in the broad rock engineering disciplines(e.***.civil,hard rock),a recent review of over 60 Slope failures suggests these methods have limited suitability for modelling the complex failure mechanisms observed in excavated coal mine Slopes.Kinematic techniques do not adequately capture the rock mass component of excavated Slope failure and do not provide a geospatial location of potential failure,while 2D limit equilibrium techniques do not adequately capture the 3D mechanisms of excavated Slope failures.Methods which do consider the 3D mechanisms of Slope failure are summarized for industry consideration and application.

关键词： Slope stability 2D 3D Open cut coal mine Limit equilibrium

Slope Stability Analyses of Outang Landslide Based on the Peak and Residual Shear Strength Behavior

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工程科学与技术 2019年第4期51卷 55-68页

作者： YANG Xiuhan VANAPALLI Sai Dept.of Civil Eng. Univ.of Ottawa

Most of the natural and compacted fine-grained soil Slopes that are in saturated or unsaturated condition undergo a large deformation prior to reaching failure conditions.Such Slopes should be designed taking account of their strain-softening behavior using the residual shear strength (RSS) parameters.In this paper,the Slope stability of a recently reactivated Outang landslide near the Three Gorges Dam in China is analyzed based on the RSS parameters of unsaturated soils.In addition,comparisons are provided in the FOS values of Slope using both the peak shear strength (PSS) and RSS parameters.Firstly,a series of site investigations of the hydrologic and geologic conditions,ground surface displacements and cracks were described.The PSS and RSS behaviors of the sliding soils derived from a series of direct shear test results performed on saturated and unsaturated soil specimens are summarized.Secondly,a series of Slope stability analysis were conducted considering the precipitation and Yangtze River water level variation within a representative period of 7 months,based on the PSS and the RSS properties.In this study,three different scenarios were considered,which include: i) considering only the precipitation with a constant water level;ii) considering only the decrease in water level without rainfall;iii) considering the combination of precipitation and decrease in water level.In each scenario,four steps were included to calculate the values of factor of safety (FOS) at different times.1) A steady-state seepage analysis was conducted with a constant total head at 525 m on the left boundary and 175 m on the Slope surface below the Yangtze River water level.The initial pore water pressures were simulated in the Slope under no precipitation and variation of water level.2) A specific boundary condition was applied on the Slope surface to model the precipitation and Yangtze River water level variation.A transient seepage analysis was conducted to calculate pore water pressures at different times based on the initial po

关键词： unsaturated soil landslide reactivation residual shear strength Slope stability analysis

A comparative study of pseudo-static Slope stability analysis using different design codes

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Water Science and Engineering 2018年第4期11卷 310-317页

作者： Xin-guang Yang En-di Zhai Yuan Wang Zhong-bo Hu Central Research Institute of Building and Construction Co. Ltd. MCC Group Beijing 100088 China Goldwind Science & Technology Co. Ltd. Beijing 100176 China College of Mechanics and Materials Hohai University Nanjing 210098 China China Three Gorges Corporation Beijing 100038 China

Many researchers have developed new calculation methods to analyze seismic Slope stability problems, but the conventional pseudo-static method is still widely used in engineering design due to its simplicity. Based on the Technical Code for Building Slope Engineering(GB 50330-2013) of China and the Guidelines for Evaluating and Mitigating Seismic Hazards in California(SP117), a comparative study on the pseudo-static method was performed. The results indicate that the largest difference between these two design codes lies in determination of the seismic equivalence reduction factor( f_(eq)). The GB 50330-2013 code specifies a single value for f_(eq) of 0.25. In SP117, numerous factors,such as magnitude and distance, are considered in determining f_(eq). Two case studies show that the types of Slope stability status evaluated by SP117 are in agreement with those evaluated by the seismic time-history stability analysis and Newmark displacement analysis. The factors of safety evaluated by SP117 can be used in practice for safe design. However, the factors of safety evaluated by GB 50330-2013 are risky for Slope seismic design.

关键词： Earthquake Slope stability Pseudo-static method Design code

Prediction of the Slope Solute Loss Based on BP Neural Network

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Computers, Materials & Continua 2021年第12期69卷 3871-3888页

作者： Xiaona Zhang Jie Feng Zhiguo Yu Zhen Hong Xinge Yun School of Hydrology and Water Resources Nanjing University of Information Science&TechnologyNanjing210044China Water Resources Research Institute China Institute of Water Resources and Hydropower ResearchBeijing100044China Department of Geography and Environmental Sustainability University of OklahomaNorman73071USA

The existence of soil macropores is a common phenomenon.Due to the existence of soil macropores,the amount of solute loss carried by water is deeply modified,which affects watershed hydrologic response.In this study,a new improved BP(Back Propagation)neural network method,using Levenberg–Marquand training algorithm,was used to analyze the solute loss on Slopes taking into account the soil macropores.The rainfall intensity,duration,the Slope,the characteristic scale of macropores and the adsorption coefficient of ions,are used as the variables of network input layer.The network middle layer is used as hidden layer,the number of hidden nodes is five,and a tangent transfer function is used as its neurons transfer function.The cumulative solute loss on the Slope is used as the variable of network output layer.A linear transfer function is used as its neurons transfer function.Artificial rainfall simulation experiments are conducted in indoor experimental tanks in order to verify this model.The error analysis and the performance comparison between the proposed method and traditional gradient descent method are done.The results show that the convergence rate and the prediction accuracy of the proposed method are obviously higher than that of traditional gradient descent method.In addition,using the experimental data,the influence of soil macropores on Slope solute loss has been further confirmed before the simulation.

关键词： Solute loss soil macropores improved BP neural network Slope

Comparative study of mining methods for reserves beneath end Slope in flat surface mines with ultra-thick coal seams

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International Journal of Mining Science and Technology 2017年第6期27卷 1065-1071页

作者： Zha Zhengao Ma Li Li Kemin Ding Xiaohua Xiao Shuangshuang School of Mines China University of Mining and Technology Xuzhou 221116 China School of Energy Engineering Xi’an University of Science and Technology Xi’an 710054 China State Key Laboratory for Geomechanics & Deep Underground Engineering China University of Mining and Technology Xuzhou 221116 China

The paper aims to identify a reasonable method for mining ultra-thick coal seams in an end-Slope in surface mine, With a case study of Heidaigou surface coal mine(HSCM), the paper conducted a comparative research on three mining methods, namely Underground Mining Method(UMM), Highwall Mining System(HMS) and Local Steep Slope Mining Method(LSSMM). A model was firstly established to simulate the impact that UMM and HMS exert on monitoring points and surface deformation. The way that stripping and excavation amount varies with different Slope angle, and the corresponding end Slope stability were analyzed in the mode of LSSMM. Then a TOPSIS model was established by taking into account six indicators such as recovery ratio, technical complexity and adaptability, the impact on surface mining production, production safety and economic benefits. Finally, LSSMM was determined as the best mining method for mining ultra-thick coal seams in end Slope in HSCM.

关键词： Ultra-thick coal seam End wall in surface mine Highwall Mining System Local steep Slope Resource exploitation

Effect of hysteresis on the stability of residual soil Slope

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International Soil and Water Conservation Research 2019年第3期7卷 226-238页

作者： Christofer Kristo Harianto Rahardjo Alfrendo Satyanaga School of Civil and Environmental Engineering Nanyang Technological UniversityHall of Residence 9Block 46#04-867Singapore639811Singapore

Soil-water characteristic curve (SWCC) is an essential parameter in unsaturated soil mechanics.Matric suction in unsaturated residual soils changes with varying climatic conditions associated with cyclic drying-wetting conditions that result in hysteresis in the SWCC.The soil mechanical behaviour under wetting is crucial since numerous rainfall-induced Slope failures occur during the wetting process.However,many Slope stability analyses were carried out using drying SWCC.Consequently,the factor of safety (FoS) calculation may not represent the actual field condition.This paper presents the effect of hysteresis in SWCC on the stability of unsaturated residual soil Slopes from Bukit Timah Granite in Singapore.The study focused on the analyses considering the differences in pore-water pressure and water content variations under drying and wetting conditions by performing numerical seepage and stability analyses.Each analysis was carried out on a Slope subjected to dry and rainy periods under three different conditions:i) using only drying SWCC;ii) using only wetting SWCC;iii) using combined drying and wetting SWCCs.The results indicated that the FoS variations obtained from the numerical analyses incorporating combined SWCC matched more closely those obtained by incorporating only wetting SWCC than those obtained by incorporating only drying SWCC,regardless of the wetting or drying processes that the soil experienced.Moreover,the numerical analyses under high rainfall intensity by incorporating only wetting SWCC gave a more conservative FoS as compared to those obtained by incorporating combined SWCC.Numerical analyses incorporating only drying SWCC gave the most conservative FoS regardless of rainfall intensity.

关键词： SWCC Hysteresis Rainfall Seepage Slope stability

Investigation of rockfall-prone road cut Slope near Lengpui Airport,Mizoram,India

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第1期11卷 146-158页

作者： A.K.Verma Sahil Sardana Pushpendra Sharma Lal Dinpuia T.N.Singh Department of Mining Engineering Indian Institute of Technology (Banaras Hindu Universiy) Department of Mining Engineering Indian Institute of Technology (Indian School of Mines) Department of Civil Engineering Lassonde School of Engineering York University Department of Ceology Pachhunga University College Department of Earth Sciences Indian Institute of Technology Bombay

Rockfall is one of severe natural hazards that are frequently reported in northeast region of India. It carries rock block falling from the cliff with high velocities and energies which can result in damages to vehicles, disruption to transportation, injuries and fatalities. The massive rockfall event which occurred in April 2017 on the highway NH-44 A, near Lengpui Airport, blocked the traffic for 1 d, and fortunately,no casualties were reported as the event occurred in the night. This is the only highway connecting the Aizawl city to the airport and the region is highly prone to rockfall events. Hence assessment of rockfall along this highway is necessary. In the current study, rockfall hazard assessment has been carried out on three locations by rockfall hazard rating system(RHRS). During pre-failure analysis, the result shows that most hazardous Slopes have RHRS score of 639. The Slopes were found to be vulnerable and later on the rockfall activity occurred. Three-dimensional(3 D) stability analysis has been carried out using 3 DEC software package to analyze the failure behavior and to decide the rockfall-prone zone(unstable blocks)for Slope. The total displacement of 2.24 cm and velocity of 2,25 mm/s of the failed block have been observed in the numerical analysis. Further, the rockfall vulnerable zone(unstable blocks) is considered to determine the parameters such as run-out distance, bounce height and energies of the falling rock blocks. The maximum total kinetic energy of 5047 kJ has been observed in the numerical analysis with the maximum run-out distance up to 18 m.

关键词： Rockfall hazards Rockfall simulation Rockfall hazard rating system(RHRS) Road cut Slopes Slope stability