The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were ca...The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake.Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers.When seismic wave propagates to tunnels,the weak interlayers and rock intersecting areas present complex wave field distribution characteristics.The dynamic responses of the slope are influenced by the frequency,amplitude,and direction of seismic waves.The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency,peaking at 20 Hz.Additionally,the seismic damage process of slope is categorized into elastic(2-3 m/s^(2)),elastoplastic(4-5 m/s^(2))and plastic damage stages(≥6.5 m/s^(2)).In elastic stage,ΔMPGA(ratio of acceleration amplification factor)increases with increasing seismic intensity,without obvious strain distribution change.In plastic stage,ΔMPGA begins to gradually plummet,and the strain is mainly distributed in the damaged area.The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer,cracking failure of tunnel lining,formation of persistent cracks on the slope crest and waist,development and outward shearing of the sliding mass,and buckling failure at the slope foot under extrusion of the upper rock body.This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.展开更多
0 INTRODUCTION Geohazards in mountainous regions pose significant risks to the construction and safe operation of transportation,water conservancy,and other critical infrastructure projects.Engineering geological inve...0 INTRODUCTION Geohazards in mountainous regions pose significant risks to the construction and safe operation of transportation,water conservancy,and other critical infrastructure projects.Engineering geological investigations are crucial for disaster prevention and mitigation.展开更多
A procedure of kinematic analysis is presented in this study to assess the reinforcement force of geosynthetics required under seismic loadings, particularly for steep slopes which are hardly able to maintain its stab...A procedure of kinematic analysis is presented in this study to assess the reinforcement force of geosynthetics required under seismic loadings, particularly for steep slopes which are hardly able to maintain its stability. Note that curved sloping surfaces widely exist in natural slopes, but existing literatures were mainly focusing on a planar surface in theoretical derivation, due to complicated calculations. Moreover, the non-uniform soil properties cannot be accounted for in conventional upper bound analysis. Pseudo-dynamic approach is used to represent horizontal and vertical accelerations which vary with time and space. In an effort to resolve the above problems, the discretization technique is developed to generate a discretized failure mechanism, decomposing the whole failure block into various components. An elementary analysis permits calculations of rates of work done by external and internal forces. Finally, the upper bound solution of the required reinforcement force is formulated based on the work rate-based balance equation. A parametric study is carried out to give insights on the implication of influential factors on the performance of geosynthetic-reinforced steep slopes.展开更多
During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines...During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines.Numerical simulation based on discrete element theory can be used to explore the characteristics and mechanism of action of deformation and failure of a slope under complex geological and multi-layer mining conditions.By utilising PFC2 D(particle flow code) software,the deformation and failure characteristics of a high-steep slope in Faer Coal Mine in Guizhou Province,China were investigated.Additionally,the mechanism of influence of different numbers of mining layers on the deformation and failure of the high and steep slope was elucidated.The result showed that after the goaf passed by the slope toe,multi-layer mining aggravated the subsidence and deformation of the slope toe:the slope toppled forward as it sank.The toppling of the slope changed the slope structures:the strata in the front of the slope were transformed from anti-dip to down-dip features.Extruded by collapsedtoppled rock mass,the slope toe and the rock mass located in the lower part of the slope toe generally exhibited a locking effect on the slope.Multi-layer mining degraded the overall stability of the slope,in that the total displacement of the slope was much greater than the total mining thickness of the coal seams.Based on the aforementioned research,ideas for preventing and controlling geological disasters during mining operations under a high-steep slope were proposed.展开更多
The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vege...The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vegetation and porous characteristics of the soil and rock mass, the steep slope will be destabilized and induce mud-rock flow or derive hazard easily. Firstly, based on the classical slope reinforcement theory, some regularity between the shear and displacement in the destabilized zone of the slope with or without root strength contribution is presented. Then, based on the experimental and statistical analysis of root strength, hydrological characteristics and stability status, etc., some possible biotechnical techniques for reinforcement of the steep slope have been suggested. These methods are important for quantitative analysis of destabilization of the slope and design of the biotechnical reinforcement.展开更多
Monitoring the stability of steep slopes of open-pit mines is a major issue relating to production safety in mines.In order to determine the technical parameters of a new type of supervising system applied in monitori...Monitoring the stability of steep slopes of open-pit mines is a major issue relating to production safety in mines.In order to determine the technical parameters of a new type of supervising system applied in monitoring steep slopes of open-pit mines,the MSARMA method was used to establish analytical models for the monitoring system,given various parameter settings based on the description of mechanical monitoring principles.We used this sensitivity analysis to conclude that the setting of the most sensitive location of a mechanical monitoring system should be within a range of 1/5～1/2 of the lower part in a vertical direction of steep slopes,with a rational and feasible range of the dip angle setting between 0°～20°.Given the analytical results of our on-site experiments,we have shown that the parameters determined reflect the stability of steep slopes accurately and effectively.These conclusions provide a basis for the application of a new type of steep slope stability monitoring technology in open-pit mines.展开更多
The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated...The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation （stress loading and unloading processes）, the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.展开更多
The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pi...The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pingzhuang Western Surface Mine and based on strength reduction method, the dynamic instability processes of the top high and steep slope was simulated. Also, the landslide mode was determined, the characteristics of the displacement distribution, the deformation, failure, and the stress distribution in the slope were demonstrated, and the stability was calculated. Conclusions can be drawn as follows： the landslide or failure of high and steep slopes on a surface mine is a gradual process, in which the slope undergoes the generation, expansion, and connection of the fractures and the displacement increases until landslide occurs; a small portion of the upper rocks fail due to the tension and the lower rocks fail due to the shear; the potential sliding surface is combined and the essential cause of the landslide is the shear stress concentration.展开更多
With the rapid development of my country’s economy, the demand for infrastructure construction is also increasing. However, in most areas of China, the terrains are mountainous and hilly. Some projects have to be bui...With the rapid development of my country’s economy, the demand for infrastructure construction is also increasing. However, in most areas of China, the terrains are mountainous and hilly. Some projects have to be built on steep slopes. Choosing viaducts or half-bridges on high-steep slopes is not only conducive to the protection of the surrounding environment, but also conducive to the stability of the slope. Bridges usually choose the form of pile </span><span style="font-family:Verdana;">foundation-high pier bridge. This paper uses numerical simulation to study and analyze the bridge pile foundation of the slope section. Relying on actual</span><span style="font-family:Verdana;"> engineering, use the finite element software ABAQUS6.14 to establish a three-dimensional finite element model to study the bearing mechanism and mechanical characteristics of the pile foundation under vertical load, horizontal load and inclined load, discuss the influence of the nature of the soil around the pile and the stiffness of the pile body on the deformation and internal force of the bridge pile foundation in the slope section. The analysis results show that the horizontal load has a great influence on the horizontal displacement of the pile, but has a small influence on the vertical displacement, and the vertical load is just the opposite. Inclined load has obvious “p-Δ” effect. The increase in soil elastic modulus and pile stiffness will reduce the displacement of the pile foundation, but after reaching a certain range, the displacement of the pile foundation will tend to be stable. Therefore, in actual engineering, if the displacement of the pile foundation fails to meet the requirements, the hardness of the soil and the stiffness of the pile can be appropriately increased, but not blindly.展开更多
In order to study bearing characteristics of bridge pile at steep slope under complex loads in mountians, according to double pile-column bridge piers engineering at steep slope and test models in laboratory, finite e...In order to study bearing characteristics of bridge pile at steep slope under complex loads in mountians, according to double pile-column bridge piers engineering at steep slope and test models in laboratory, finite element analysis of pile-column bridge piers was carried out using software ADINA under different loadings, such as horizontal loading in the longitudinal direction along bridge, vertical loadings, slope top loadings and complex loadings. The numerical simulation results show that displacements of front pile pier top and back pile pier top are different under horizontal loadings in the longitudinal direction along bridge or vertical loadings, the displacements of front pile pier top are higher than those of back pile pier top, and its difference increases with the increase of loadings. Vertical displacements will also appear under slope top loadings, and displacements of front pier top are higher than those of back pier top too, while its difference reduces with the increase of loadings. Displacements of both front pile pier top and back pile pier top under comlex loading are larger than those under single loading.展开更多
Steep-slope cropland plays a vital role in food production,economic development,ecosystem diversity,and Eu-ropean cultural heritage.However,these systems are susceptible to extreme weather events.The 2022 summer droug...Steep-slope cropland plays a vital role in food production,economic development,ecosystem diversity,and Eu-ropean cultural heritage.However,these systems are susceptible to extreme weather events.The 2022 summer drought significantly impacted European agriculture,but the specific effects on steep-slope crops remain uncer-tain.Clarifying this is essential for comprehending similar future events and for implementing effective water management strategies to ensure the sustainability of steep-slope agriculture and associated ecosystem services.This study quantitatively analyzes the spatial distribution of twelve major European steep-slope(>12%)crops and assesses agricultural drought severity during the 2022 events using open-access spatial data.The satellite-based Vegetation Health Index(VHI)is utilized to identify critical hotspots.Results show that olive grove is the most widespread crop in steep slope agriculture(34%of total area),followed by wheat(24%),maize(16%),and vineyard(11%).Almost half of the steep-slope agriculture in Europe suffered drought during summer 2022.Vineyards were hardest affected at 79%,primarily in northern Portugal,northern Spain,southern France,and central Italy.Sunflowers followed at 62%,mainly in Spain,central Italy,southern France,and northern Roma-nia.Olive groves ranked third at 59%,with the most impact in northern Portugal,southern and central Spain,and southern Italy.Maize was also significantly affected at 54%.In this paper,we therefore highlight the need to increase steep-slope agriculture resilience by improving water management and promoting sustainable land practices.展开更多
Based on the study of the slope with gently granular structure in Xingqiao open mine, a new safety cleaning bank mode for steep slope mining was developed, including setting up dint cut, and forming natural retaining ...Based on the study of the slope with gently granular structure in Xingqiao open mine, a new safety cleaning bank mode for steep slope mining was developed, including setting up dint cut, and forming natural retaining wall based on the character of gentle incline slope. It can effectively eliminate the impact of sliding body on the bottom working place and slope body, reduce the dilution of ore, keep rainwater from upper steps away, decrease influence of the weak intermediate layer, and cut cost of disposal waste rock. The safety and reliability of the mode were analyzed and verified from 3 aspects: static load calculation, ANSYS simulation of dynamic loading and spot experiment. The result of static loading calculation shows that the retaining wall can support accumulation and extrusion of granular body, and the glide or overturn disaster will not take place. The simulations of dynamic loading show that the retaining wall remains stable until sliding body collapses from 360 m (10 sublevels). Only one new safety cleaning bank in each 15 sublevels can fully meet the need of engineering. The new mode sustains steep slope (mining,) increases the angle of ultimate slope, and reduces invalid overburden amount of rock by 3%5%. The result of spot experiment has verified the exactness of the above calculations and simulations.展开更多
A method of a large experimental model coupled with a smaller one and an equivalent replacement method are adopted to study the deformation and the failure mechanism of a steep rock slope, in order to solve the diffic...A method of a large experimental model coupled with a smaller one and an equivalent replacement method are adopted to study the deformation and the failure mechanism of a steep rock slope, in order to solve the difficult problems in space gravity similitude of the experimental model on steep rock slope with weak layers. The experimental results on the Lianziya Precipice of the Yangtze Three Gorges are in general agreement with the field observations. The experimental method adopted is proved to be successful in molding the complex geological condition especially with the weak layers.展开更多
Steep-slope agricultural landscapes are under threat due to climate change.On the one hand,the growing fre-quency of extreme high-intensity rainfall events concentrated in both temporal and spatial scales are causing ...Steep-slope agricultural landscapes are under threat due to climate change.On the one hand,the growing fre-quency of extreme high-intensity rainfall events concentrated in both temporal and spatial scales are causing flash floods or slope failure risk scenarios.On the other hand,future climate projections indicate a significant expansion of arid zones in the steep slope agricultural system.There is evidence that these landscapes face a high risk of growing water scarcity.Considering their unique role in crop production,ecosystem diversity,and crop production,ecosystem diversity,and cultural heritage,understanding sustainable water resource manage-ment for mitigating climate change-induced drought has never been more urgent than today.In these landscapes,unique indigenous knowledge of water conservation is adopted to manage water resources improving their re-silience optimally.It is,therefore,necessary to promote water storage to mitigate floods or increase the resilience to prolonged drought(creating at the same time favourable conditions for biodiversity).Modern technological advances(e.g.,high-resolution remote sensing and GIS-based modelling)are crucial in supporting these activities and understanding earth’s surface processes.展开更多
In order to analyze the deformation and stress characteristics of the pile foundation on the slope<span><span><span style="font-family:" capt",serif;"="" pro="" m...In order to analyze the deformation and stress characteristics of the pile foundation on the slope<span><span><span style="font-family:" capt",serif;"="" pro="" minion="">, </span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">this paper uses the finite element software Abaqus for numerical simulation.</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion=""> </span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">The displacement and stress data of pile under different working conditions (the combination of heap load and vertical load and horizontal load and inclined load) were collected</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">;</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">the distribution of pile displacement, axial force and bending moment were analyzed. Simulation results show that: slope top loading has little effect on vertical displacement</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">;</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion=""> when the heap load exceeds 200 kPa, the horizontal displacement is greatly affected. Pile axial force decreases with pile burial depth</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">;</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">pile lateral resistance plays a more adequate role in the rock and soil layer. The bending moment of double pile foundation is positive at the top and negative at the bottom.</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion=""> </span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">Applied oblique load has obvious p-Δ effect.</span></span></span>展开更多
Mountainous ecosystem soils are subject to colonization nowadays for agri</span><span style="font-family:Verdana;">cultural purposes due to an increasing population in towns making the</span&g...Mountainous ecosystem soils are subject to colonization nowadays for agri</span><span style="font-family:Verdana;">cultural purposes due to an increasing population in towns making the</span><span style="font-family:Verdana;"> detailed </span><span style="font-family:Verdana;">characterization of such soils indispensable. This work aims to characterize</span><span style="font-family:Verdana;"> the steep slopes soils of the Dschang hills and to evaluate their fertility level for </span><span style="font-family:Verdana;">agricultural valorization. Thus, four soil profiles were dug at various topographic</span><span style="font-family:Verdana;"> positions (summit (SP), shoulder (MP), backslope (BP) and footslope (PP)) following a toposequence. Samples of disturbed and undisturbed soils were taken and analyzed in the laboratory according to standard methods. The Fertility</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Capability</span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">Classification (FCC) and simple limitation methods were used to identify major agricultural constraints. The main results show that </span><span style="font-family:Verdana;">profiles thickness is moderate, between 0 and 120 cm, with a high sand</span><span style="font-family:Verdana;"> content </span><span style="font-family:Verdana;">(at least 50%) over the entire toposequence, especially at the surface. The</span><span style="font-family:Verdana;"> study site has four types of soils, namely Eutric</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">Cambisols (ochric) in SP and L</span><span style="font-family:Verdana;">eptic</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Eutric</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Cambisols (Humic) in MP, Eutric</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Cambisols (Humic) in BP</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> and Stagnic</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Oxygleyic</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Dystric</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Gleysols</span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">(Humic) in pp. The soils are very acidic at PP, moderately acidic at BP and SP and slightly acidic at MP. Organic matter is higher at the surface than at depth at the topographic segments of MP, BP and PP and low to SP. The C/N ratio is high (>17) in all profiles except P4 </span><span style="font-family:Verdana;">(<10). In addition, the cation exchange capacity (CEC), the sum of</span><span style="font-family:Verdana;"> exchangeable bases, total nitrogen and available phosphorus is low in all profiles. The Ca/</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">Mg/K balance in all the profiles shows a cation imbalance and a relatively </span><span style="font-family:Verdana;">high concentration of exchangeable potassium compared to the ideal</span><span style="font-family:Verdana;"> situation (76% Ca, 18% Mg and 6% K). The major constraints to crop production are: aluminum toxicity (a) and nutrients leaching (e), textural discontinuity (LS), flooding (g), low nutrient reserve (k), sand (S), clay (C) and slope (t). Hence the fertility capacity classes of these soils are CCaegk (PP), SSek (BP), SSte (MP) and LSaek (SP). To improve the yield, it will require off-season crop cultivation, fertilization and liming, and earthworks.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.52109125)the Natural Science Foundation of Jiangsu Province,China (Grant No.BK20231217)the Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Chinese Academy of Sciences (Grant No.SKLGME023001).
文摘The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake.Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers.When seismic wave propagates to tunnels,the weak interlayers and rock intersecting areas present complex wave field distribution characteristics.The dynamic responses of the slope are influenced by the frequency,amplitude,and direction of seismic waves.The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency,peaking at 20 Hz.Additionally,the seismic damage process of slope is categorized into elastic(2-3 m/s^(2)),elastoplastic(4-5 m/s^(2))and plastic damage stages(≥6.5 m/s^(2)).In elastic stage,ΔMPGA(ratio of acceleration amplification factor)increases with increasing seismic intensity,without obvious strain distribution change.In plastic stage,ΔMPGA begins to gradually plummet,and the strain is mainly distributed in the damaged area.The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer,cracking failure of tunnel lining,formation of persistent cracks on the slope crest and waist,development and outward shearing of the sliding mass,and buckling failure at the slope foot under extrusion of the upper rock body.This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.
基金financially supported by the National Key R&D Program of China(No.2022YFC3080200)。
文摘0 INTRODUCTION Geohazards in mountainous regions pose significant risks to the construction and safe operation of transportation,water conservancy,and other critical infrastructure projects.Engineering geological investigations are crucial for disaster prevention and mitigation.
文摘A procedure of kinematic analysis is presented in this study to assess the reinforcement force of geosynthetics required under seismic loadings, particularly for steep slopes which are hardly able to maintain its stability. Note that curved sloping surfaces widely exist in natural slopes, but existing literatures were mainly focusing on a planar surface in theoretical derivation, due to complicated calculations. Moreover, the non-uniform soil properties cannot be accounted for in conventional upper bound analysis. Pseudo-dynamic approach is used to represent horizontal and vertical accelerations which vary with time and space. In an effort to resolve the above problems, the discretization technique is developed to generate a discretized failure mechanism, decomposing the whole failure block into various components. An elementary analysis permits calculations of rates of work done by external and internal forces. Finally, the upper bound solution of the required reinforcement force is formulated based on the work rate-based balance equation. A parametric study is carried out to give insights on the implication of influential factors on the performance of geosynthetic-reinforced steep slopes.
基金funded by the National Natural Science Foundation of China (Grants No. 41877273)the Innovative Research Groups of the National Natural Science Foundation of China (Grants No. 41521002)+1 种基金the State Key Laboratory of Geohazard Disaster Prevention and Geoenvironment Protection (Chengdu University of Technology) (Grants No. SKLGP2017Z016)the Guizhou Provincial Geological Environment Monitoring Institute, and the Faer Coal Mine。
文摘During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines.Numerical simulation based on discrete element theory can be used to explore the characteristics and mechanism of action of deformation and failure of a slope under complex geological and multi-layer mining conditions.By utilising PFC2 D(particle flow code) software,the deformation and failure characteristics of a high-steep slope in Faer Coal Mine in Guizhou Province,China were investigated.Additionally,the mechanism of influence of different numbers of mining layers on the deformation and failure of the high and steep slope was elucidated.The result showed that after the goaf passed by the slope toe,multi-layer mining aggravated the subsidence and deformation of the slope toe:the slope toppled forward as it sank.The toppling of the slope changed the slope structures:the strata in the front of the slope were transformed from anti-dip to down-dip features.Extruded by collapsedtoppled rock mass,the slope toe and the rock mass located in the lower part of the slope toe generally exhibited a locking effect on the slope.Multi-layer mining degraded the overall stability of the slope,in that the total displacement of the slope was much greater than the total mining thickness of the coal seams.Based on the aforementioned research,ideas for preventing and controlling geological disasters during mining operations under a high-steep slope were proposed.
基金This work was financially supported by the National Natural Science Foundation of China (No. 10402033) and the Key Lab. Foun-dation of the Ministry of Education of China (No.04JS19).
文摘The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vegetation and porous characteristics of the soil and rock mass, the steep slope will be destabilized and induce mud-rock flow or derive hazard easily. Firstly, based on the classical slope reinforcement theory, some regularity between the shear and displacement in the destabilized zone of the slope with or without root strength contribution is presented. Then, based on the experimental and statistical analysis of root strength, hydrological characteristics and stability status, etc., some possible biotechnical techniques for reinforcement of the steep slope have been suggested. These methods are important for quantitative analysis of destabilization of the slope and design of the biotechnical reinforcement.
基金Project 1053G032 supported by the Youth Science Foundation of Educational Committee of Heilongjiang Province
文摘Monitoring the stability of steep slopes of open-pit mines is a major issue relating to production safety in mines.In order to determine the technical parameters of a new type of supervising system applied in monitoring steep slopes of open-pit mines,the MSARMA method was used to establish analytical models for the monitoring system,given various parameter settings based on the description of mechanical monitoring principles.We used this sensitivity analysis to conclude that the setting of the most sensitive location of a mechanical monitoring system should be within a range of 1/5～1/2 of the lower part in a vertical direction of steep slopes,with a rational and feasible range of the dip angle setting between 0°～20°.Given the analytical results of our on-site experiments,we have shown that the parameters determined reflect the stability of steep slopes accurately and effectively.These conclusions provide a basis for the application of a new type of steep slope stability monitoring technology in open-pit mines.
基金supported by Sinoprob-Deep Exploration Program in China sponsored by Ministry of Land and Resources of the People’s Republic of China (No.0819011A90)National Natural Science Foundation of China (No.D0408/4097409)
文摘The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation （stress loading and unloading processes）, the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.
基金Supported by the National Natural Science Foundation of China （50375026） the Project of Liaoning Province Department of Education （20060387） Liaoning Province, Guideline Plan Project on Safety in Production and Development of Technology （[2009] No. 88）
文摘The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pingzhuang Western Surface Mine and based on strength reduction method, the dynamic instability processes of the top high and steep slope was simulated. Also, the landslide mode was determined, the characteristics of the displacement distribution, the deformation, failure, and the stress distribution in the slope were demonstrated, and the stability was calculated. Conclusions can be drawn as follows： the landslide or failure of high and steep slopes on a surface mine is a gradual process, in which the slope undergoes the generation, expansion, and connection of the fractures and the displacement increases until landslide occurs; a small portion of the upper rocks fail due to the tension and the lower rocks fail due to the shear; the potential sliding surface is combined and the essential cause of the landslide is the shear stress concentration.
文摘With the rapid development of my country’s economy, the demand for infrastructure construction is also increasing. However, in most areas of China, the terrains are mountainous and hilly. Some projects have to be built on steep slopes. Choosing viaducts or half-bridges on high-steep slopes is not only conducive to the protection of the surrounding environment, but also conducive to the stability of the slope. Bridges usually choose the form of pile </span><span style="font-family:Verdana;">foundation-high pier bridge. This paper uses numerical simulation to study and analyze the bridge pile foundation of the slope section. Relying on actual</span><span style="font-family:Verdana;"> engineering, use the finite element software ABAQUS6.14 to establish a three-dimensional finite element model to study the bearing mechanism and mechanical characteristics of the pile foundation under vertical load, horizontal load and inclined load, discuss the influence of the nature of the soil around the pile and the stiffness of the pile body on the deformation and internal force of the bridge pile foundation in the slope section. The analysis results show that the horizontal load has a great influence on the horizontal displacement of the pile, but has a small influence on the vertical displacement, and the vertical load is just the opposite. Inclined load has obvious “p-Δ” effect. The increase in soil elastic modulus and pile stiffness will reduce the displacement of the pile foundation, but after reaching a certain range, the displacement of the pile foundation will tend to be stable. Therefore, in actual engineering, if the displacement of the pile foundation fails to meet the requirements, the hardness of the soil and the stiffness of the pile can be appropriately increased, but not blindly.
基金Projects(50878083,50578060)supported by the National Natural Science Foundation of ChinaProject(200831878531)supported by the Ministry of Transportation of China
文摘In order to study bearing characteristics of bridge pile at steep slope under complex loads in mountians, according to double pile-column bridge piers engineering at steep slope and test models in laboratory, finite element analysis of pile-column bridge piers was carried out using software ADINA under different loadings, such as horizontal loading in the longitudinal direction along bridge, vertical loadings, slope top loadings and complex loadings. The numerical simulation results show that displacements of front pile pier top and back pile pier top are different under horizontal loadings in the longitudinal direction along bridge or vertical loadings, the displacements of front pile pier top are higher than those of back pile pier top, and its difference increases with the increase of loadings. Vertical displacements will also appear under slope top loadings, and displacements of front pier top are higher than those of back pier top too, while its difference reduces with the increase of loadings. Displacements of both front pile pier top and back pile pier top under comlex loading are larger than those under single loading.
基金funding from the European Union Next-GenerationEU(PIANO NAZIONALE DI RIPRESA E RESILIENZA(PNRR)-MISSIONE 4 COMPONENTE 2,INVESTIMENTO 1.4-D.D.103217/06/2022,CN00000022).
文摘Steep-slope cropland plays a vital role in food production,economic development,ecosystem diversity,and Eu-ropean cultural heritage.However,these systems are susceptible to extreme weather events.The 2022 summer drought significantly impacted European agriculture,but the specific effects on steep-slope crops remain uncer-tain.Clarifying this is essential for comprehending similar future events and for implementing effective water management strategies to ensure the sustainability of steep-slope agriculture and associated ecosystem services.This study quantitatively analyzes the spatial distribution of twelve major European steep-slope(>12%)crops and assesses agricultural drought severity during the 2022 events using open-access spatial data.The satellite-based Vegetation Health Index(VHI)is utilized to identify critical hotspots.Results show that olive grove is the most widespread crop in steep slope agriculture(34%of total area),followed by wheat(24%),maize(16%),and vineyard(11%).Almost half of the steep-slope agriculture in Europe suffered drought during summer 2022.Vineyards were hardest affected at 79%,primarily in northern Portugal,northern Spain,southern France,and central Italy.Sunflowers followed at 62%,mainly in Spain,central Italy,southern France,and northern Roma-nia.Olive groves ranked third at 59%,with the most impact in northern Portugal,southern and central Spain,and southern Italy.Maize was also significantly affected at 54%.In this paper,we therefore highlight the need to increase steep-slope agriculture resilience by improving water management and promoting sustainable land practices.
文摘Based on the study of the slope with gently granular structure in Xingqiao open mine, a new safety cleaning bank mode for steep slope mining was developed, including setting up dint cut, and forming natural retaining wall based on the character of gentle incline slope. It can effectively eliminate the impact of sliding body on the bottom working place and slope body, reduce the dilution of ore, keep rainwater from upper steps away, decrease influence of the weak intermediate layer, and cut cost of disposal waste rock. The safety and reliability of the mode were analyzed and verified from 3 aspects: static load calculation, ANSYS simulation of dynamic loading and spot experiment. The result of static loading calculation shows that the retaining wall can support accumulation and extrusion of granular body, and the glide or overturn disaster will not take place. The simulations of dynamic loading show that the retaining wall remains stable until sliding body collapses from 360 m (10 sublevels). Only one new safety cleaning bank in each 15 sublevels can fully meet the need of engineering. The new mode sustains steep slope (mining,) increases the angle of ultimate slope, and reduces invalid overburden amount of rock by 3%5%. The result of spot experiment has verified the exactness of the above calculations and simulations.
文摘A method of a large experimental model coupled with a smaller one and an equivalent replacement method are adopted to study the deformation and the failure mechanism of a steep rock slope, in order to solve the difficult problems in space gravity similitude of the experimental model on steep rock slope with weak layers. The experimental results on the Lianziya Precipice of the Yangtze Three Gorges are in general agreement with the field observations. The experimental method adopted is proved to be successful in molding the complex geological condition especially with the weak layers.
文摘Steep-slope agricultural landscapes are under threat due to climate change.On the one hand,the growing fre-quency of extreme high-intensity rainfall events concentrated in both temporal and spatial scales are causing flash floods or slope failure risk scenarios.On the other hand,future climate projections indicate a significant expansion of arid zones in the steep slope agricultural system.There is evidence that these landscapes face a high risk of growing water scarcity.Considering their unique role in crop production,ecosystem diversity,and crop production,ecosystem diversity,and cultural heritage,understanding sustainable water resource manage-ment for mitigating climate change-induced drought has never been more urgent than today.In these landscapes,unique indigenous knowledge of water conservation is adopted to manage water resources improving their re-silience optimally.It is,therefore,necessary to promote water storage to mitigate floods or increase the resilience to prolonged drought(creating at the same time favourable conditions for biodiversity).Modern technological advances(e.g.,high-resolution remote sensing and GIS-based modelling)are crucial in supporting these activities and understanding earth’s surface processes.
文摘In order to analyze the deformation and stress characteristics of the pile foundation on the slope<span><span><span style="font-family:" capt",serif;"="" pro="" minion="">, </span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">this paper uses the finite element software Abaqus for numerical simulation.</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion=""> </span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">The displacement and stress data of pile under different working conditions (the combination of heap load and vertical load and horizontal load and inclined load) were collected</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">;</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">the distribution of pile displacement, axial force and bending moment were analyzed. Simulation results show that: slope top loading has little effect on vertical displacement</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">;</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion=""> when the heap load exceeds 200 kPa, the horizontal displacement is greatly affected. Pile axial force decreases with pile burial depth</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">;</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">pile lateral resistance plays a more adequate role in the rock and soil layer. The bending moment of double pile foundation is positive at the top and negative at the bottom.</span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion=""> </span></span></span><span><span><span style="font-family:" capt",serif;"="" pro="" minion="">Applied oblique load has obvious p-Δ effect.</span></span></span>
文摘Mountainous ecosystem soils are subject to colonization nowadays for agri</span><span style="font-family:Verdana;">cultural purposes due to an increasing population in towns making the</span><span style="font-family:Verdana;"> detailed </span><span style="font-family:Verdana;">characterization of such soils indispensable. This work aims to characterize</span><span style="font-family:Verdana;"> the steep slopes soils of the Dschang hills and to evaluate their fertility level for </span><span style="font-family:Verdana;">agricultural valorization. Thus, four soil profiles were dug at various topographic</span><span style="font-family:Verdana;"> positions (summit (SP), shoulder (MP), backslope (BP) and footslope (PP)) following a toposequence. Samples of disturbed and undisturbed soils were taken and analyzed in the laboratory according to standard methods. The Fertility</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Capability</span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">Classification (FCC) and simple limitation methods were used to identify major agricultural constraints. The main results show that </span><span style="font-family:Verdana;">profiles thickness is moderate, between 0 and 120 cm, with a high sand</span><span style="font-family:Verdana;"> content </span><span style="font-family:Verdana;">(at least 50%) over the entire toposequence, especially at the surface. The</span><span style="font-family:Verdana;"> study site has four types of soils, namely Eutric</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">Cambisols (ochric) in SP and L</span><span style="font-family:Verdana;">eptic</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Eutric</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Cambisols (Humic) in MP, Eutric</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Cambisols (Humic) in BP</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> and Stagnic</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Oxygleyic</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Dystric</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Gleysols</span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">(Humic) in pp. The soils are very acidic at PP, moderately acidic at BP and SP and slightly acidic at MP. Organic matter is higher at the surface than at depth at the topographic segments of MP, BP and PP and low to SP. The C/N ratio is high (>17) in all profiles except P4 </span><span style="font-family:Verdana;">(<10). In addition, the cation exchange capacity (CEC), the sum of</span><span style="font-family:Verdana;"> exchangeable bases, total nitrogen and available phosphorus is low in all profiles. The Ca/</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">Mg/K balance in all the profiles shows a cation imbalance and a relatively </span><span style="font-family:Verdana;">high concentration of exchangeable potassium compared to the ideal</span><span style="font-family:Verdana;"> situation (76% Ca, 18% Mg and 6% K). The major constraints to crop production are: aluminum toxicity (a) and nutrients leaching (e), textural discontinuity (LS), flooding (g), low nutrient reserve (k), sand (S), clay (C) and slope (t). Hence the fertility capacity classes of these soils are CCaegk (PP), SSek (BP), SSte (MP) and LSaek (SP). To improve the yield, it will require off-season crop cultivation, fertilization and liming, and earthworks.
