Waste Dump Slope Research Articles

Integrated modeling of waste dump slope stability

Integrated modeling of waste dump slope stability

Enhancement of mechanical stability of waste dump slope through establishing vegetation in a surface iron ore mine

The mechanical stability of waste dump is important from the economic and safety points of view. Re-vegetation is the most popular and eco-friendly approach to stabilize the waste dumps. However, not many studies address this concern and support the type of vegetation to be carried out on these waste dump slopes. This study has therefore explored the possibilities of using local species for the mechanical stability of the waste dump in surface iron ore mine for long tern protection of the environment. Commonly available local species those are likely to fit into the ecosystem and adapt quickly to the climate have been used for vegetation in the waste dump in the present study. The increased shear strength of the vegetated waste dump is determined by carrying out in situ field tests. A shear box (0.15×0.15×0.15 m) specifically designed and fabricated was used to determine the increased mechanical stability of the vegetated waste dump on the surface iron mine. From the analysis of in situ field data, it is concluded that the mechanical stability of waste dump has significantly improved with the application of local species as vegetation on the waste dump, with a possibility of extending its role towards maintaining long term stability.

Enhancement of mechanical stability of waste dump slope through establishing vegetation in a surface iron ore mine

From the perspective of economic and safety, the mechanical stability of a waste dump is crucial; therefore, re-vegetation is considered to be the most pertinent and eco-friendly approach to achieve this goal. However, not many studies address this concern and support the type of vegetation to be carried out on these waste dump slopes. This study has, therefore, explored the possibilities of using local species for the mechanical stability of the waste dump in surface iron ore mine for long-term protection of the environment. Commonly available local species are considered as prospective candidates that can adapt quickly to the climate and fit into the ecosystem, and an in situ test was used to calculate the shear strength of the vegetated waste dump. This test used a customized shear box (0.15 m × 0.15 m × 0.15 m) to evaluate the increased mechanical stability of the vegetated waste dump on the surface iron mine. From the analysis of in situ field data, it is concluded that the mechanical stability of waste dump has significantly improved with a possibility of extending its role toward maintaining long-term stability.

Stability analysis of slope at a disused waste dump by two-wedge model

This study presents a large-scale failure of a disused external waste dump at an iron mine, one of the largest iron open pit mines in China. The dump is developed three beaches covering a total height of 130 m from the ground surface. It is dumped on an inclined clay layer with a maximum dip angle of 13° and average thickness of 9.34 m. The slide involved 7000000 m3 in volume of loose mass i.e. waste material, gravel and clay. In order to estimate the failure mode for slide, numerical simulation on failure mechanics of dump is performed by FLAC3D, and a physical model test on failure process of dump is carried out by the floor friction model. Results show that the waste dump slope moves horizontally along the clay layer in first. The horizontal movement of lower beaches results in the decrease of the shear resistance to lateral slide. Then, tensile cracks are generated in the top crest of the slope. Such failures with two planar slip surfaces have occurred at clay basement and through tensile cracks. With time, an obvious interface between lower block with large horizontal movement and upper block with large vertical movement is generated and then developed into the third planar slip surface. Sliding masses are divided by three slip surfaces into two wedges. A two-wedge model is established to evaluate stability for the waste dump. Factor of safety and failure mode calculated by the two-wedge method are nearly the same with those by strength reduction method.

Mechanical characteristics of dip basement effects on dump stability in the Shengli open pit mine in Inner Mongolia, China

For waste dump slopes that form basements, landslides can be prevented by determining a stability evolving law of dynamic development. Keeping this issue in mind, the relationship between the mechanical structure and stability of waste dumps with basements is studied. Three key factors that influence waste dump stability are presented, and judgment criteria for self-locking and unlocking states of dump basements are provided. From the friction coefficient of waste dump basement stability analyses of the Shengli open pit mine, the results indicate that waste dump basements on the right side of fault F8 and on the left side of fault F61 are subjected to self-locking. However, between faults F61 and F8, the basement is subjected to unlocking. Regarding the residual thrusting of unlocking areas, structure and stability optimization schemes for waste dumps in the Shengli open pit mine are provided through a mechanics analysis. Reducing the slopes and basement angles of waste dumps can enhance their stability by increasing basement roughness levels.

광산폐기물 적치사면의 불포화 특성변화 모니터링 시스템 구축

본 연구에서는 부산 임기광산 광산폐기물 사면을 대상으로 강우 침투에 따른 지반내 불포화 특성변화를 살펴보기 위하여 불포화토 특성변화 측정유닛 및 시스템을 현장에 설치하였다. 불포화토 특성변화 측정시스템은 각종 측정유닛으로부터 측정된 자료를 저장, 관리 및 전달하는 시스템으로 Data Acquisition System(DAS), Solar System 및 불포화토 특성변화 측정유닛으로 구성되어 있다. 현장에 설치된 각종 측정유닛으로부터 측정된 강우, 체적함수비, 모관흡수력 등의 자료를 정리하여 분석하였다. 이들 결과를 살펴보면 강우시 체적함수비와 모관흡수력의 변화는 강우강도에 의해 크게 영향을 받으며, 강우시와 건기시 지표면 부근에서 가장 크게 증가하였다가 감소하는 것으로 나타났다. 그리고 현장에서 측정된 모관흡수력은 5-35kPa, 체적함수비는 0.12-0.24 범위에 존재하는 것으로 나타났다. 그러나 지하수위는 강우발생 직후 바로 증가하는 것이 아니라 2-3일의 시간이 경과한 뒤 증가함을 알 수 있다. Field measurement units and a system were constructed and installed in a waste-dump slope at the Imgi mine to investigate and analyze the variations in the unsaturated characteristics of the soil. The field instrumentation system was composed of a data acquisition system (DAS), a solar system, and measuring sensors. The rainfall, matric suction, and volumetric water contents were continuously measured from the units in the instrumented site. The variations in matric suction and volumetric water content were primarily affected by the rainfall intensity. At the surface of the slope, the largest increase and decrease in the changes in matric suction and volumetric water content were observed during the wetting and drying processes, respectively. Also, the matric suction and volumetric water content were 5-35 kPa and 0.12-0.24, respectively. However, the ground water level was not suddenly increased just after rainfall but gradually increased after 2 or 3 days later.

Analyses on variations in the unsaturated characteristics of a mine waste-dump slope during rainfall

Field measurement units and a system were constructed and installed in a waste-dump slope at the Imgi mine to investigate and analyze the variations in the unsaturated characteristics of the soil. The field instrumentation system was composed of a data acquisition system, a solar system, and measuring sensors. The rainfall, matric suction, and volumetric water contents were continuously measured from the units in the instrumented site and analyzed with the soil water characteristic curve (SWCC) estimated from laboratory experiments. The variations in matric suction and volumetric water content were primarily affected by the rainfall intensity. At the surface of the slope, the largest increase and decrease in the changes in matric suction and volumetric water content were observed during the wetting and drying processes, respectively. The matric suction and volumetric water content measured from the instrumented area were compared with the SWCCs obtained from the laboratory test, and the measured data were located between the drying and wetting paths. The drying and wetting paths obtained from the laboratory test are regarded as primary drying and wetting curves, respectively. Therefore, the measured data can be defined as scanning curves, which are located between primary drying and wetting curves. The variations in matric suction according to volumetric water content were dependent on depth, and a wide range of variations was observed at shallow depths. It was confirmed that the unsaturated soil near the ground surface has the sensitive reaction induced by the infiltration and evaporation in nature.

Critical geometric parameters of slope and their sensitivity analysis: a case study in Jilin, Northeast China

An excessively high or steep slope is one of the main causes of slope instability. This research examined the slope of the waste dump of a limestone mine in Wangqing County of northeast China’s Jilin Province. Support vector regression (SVR) and a radial basis function neural network (RBFNN) were used to train and test 76 groups of collected data, and the mean absolute error (MAE), mean absolute percentage error (MAPE), and root mean square error (RMSE) values indicated that the SVR model is better than the RBFNN model. Then, 12 × 17 combinations of angles and heights for the waste dump slope were designed, and used SVR to define β cr and H cr by predicting the factor of safety (FS) under different conditions. The results demonstrated that the SVR method can be used to calculate β cr and H cr accurately. Moreover, the effects of the parameters on FS and β cr and H cr were analyzed by sensitivity analysis. The sensitivity analysis results showed that the internal friction angle (φ) is the most effective parameter acting on β cr and H cr , followed by the unit weight (γ) and cohesion (c). Furthermore, H cr is more sensitive to γ, c, and φ than β cr . These results could be useful and convenient for engineers involved in slope design and management.

Study of Numerical Simulation in Failure Modes of Waste Dump Slope

Based on the numerical simulation method and a sample slope engineer of waste dump, the failure modes of waste dump slope is analyzed. By means of analyzing working conditions such as different slope angles, single step, many steps, the failure modes of waste dump slope under different working conditions is obtained. The results show that the slope stability of multiple steps waste dump is better than the slope stability of single step waste dump, and the deformation of the slope is small.

Deformation measurements and a stability analysis of the slope at a coal mine waste dump

This study surveyed and investigated the deformation of the coal waste dump slope and the natural ground slope under the waste dump at Dogye village in Samcheock city, Gangwon Province, Korea. Multiple sets of south-north tension cracks were observed at the crest of the coal waste dump slope. These cracks were greater than 100m in length, and the resulting drop head averaged 1.0–1.5m. To investigate the behaviors of the waste dump slope and the natural slope under the waste dump, wire sensors and a rain gauge were installed at the crest of the waste dump slope, and inclinometers were installed in the natural slope of the ground under the waste dump. According to the monitoring results, the deformation at the crest of the waste dump slope steadily increased and then converged over time due to the effect of the infiltration of rain into the ground after rainfall. In addition, the horizontal deformation of the natural slope under the waste dump was affected by the accumulated precipitation. The basis of this effect is that the rate of increase of the maximum horizontal deformation tends to show increasing or convergent behavior according to the precipitation. The slope stability analysis showed that the safety factor of the natural slope before the discharge of the waste was 2.14. Meanwhile, the safety factor of the waste dump slope, including the natural slope in the dry season was 1.66 and the safety factor in the rainy season was 0.98. The natural slope before the discharge of the waste and the coal waste slope, including the natural slope remained stable during the dry season but became unstable during the rainy season, especially when the ground water level in the waste dump slope becomes rising as a result of infiltration by rainwater. The waste dump slope and the natural slope under the waste dump experienced deformation due to the increasing weight placed on the waste dump by the infiltration resulting from rainfall.

Numerical Analysis of Safety on Waste-Dumping Cover-Slope out of the Tailings Dam

Mining companies intend to solve the problem of waste dump and reduce the production cost by dumping a large number of waste soils to cover slope outside the running tailings. Therefore, in order to discuss the safety of waste dump slope covering in front of the tailings dam, numerical method was adopted to study the seepage-line change law, the pore water pressure and anti-sliding safety before and after the waste dump covering out of tailings dam. The researches show that the key to waste-dump slope safety are the drainage performance of waste dump bottom layer and the anti-sliding safety of waste dump soil. The appropriate waste dump slope work can improves the tailings dams safety and solves the waste dump problem in mining production.

Dump Load Shedding and Slope Angle of Optimization Design

In view of the local conditions of Xingshan Iron Mine North Dump, an economically safe load shedding scheme was determined. Based on critical sliding field technology, the most dangerous slip surface can be searched of different waste-dump slope angles. Once the most dangerous slip surface is fixed, limit equilibrium methods can be used to analyze the stability of the slope. The corresponding slope angle of minimum allowable safety coefficient under the most unfavorable condition was defined as the optimal slope angle of this section, and the minimum optimal slope angle of all the sections of dump was determined as the final optimal slope angel of the whole dump. This method was not any practical but also extremely economical, which can ensure the absolute safety of dump and its surroundings.

Application of geogrids in waste dump stability: a numerical modeling approach

Geosynthetic is widely used to reinforce the weak rock mass, mine waste dump, soil slopes road cut slopes, etc. The present paper discusses the effect of geogrids on the stability of mine waste dump. The stability of mine waste dump has been done by Fast Langrage Analysis of Continua (FLAC) slope software, which is based on finite difference method. Reinforcement by geogrids mainly depends on the tensile strength, aperture size of geogrids, and particle size distribution of dump rock mass. Different permutations and combinations of spacing between two geogrid sheets have been taken into consideration to study the stability of mine waste dump. The factor of safety is calculated to quantify the effect of geogrids on waste dump slope. It has been observed from numerical modeling that the maximum slope angle is 45° at a height of 10 m. The scope of increasing slope angle from 45 to 60° is evaluated using geogrids. It has been found from the study that the factor of safety increases as the spacing between geogrids decreases. Maximum strain is also plotted of each case to identify the slip circle. The positions of geogrids modify the probable slip circle or failure plane of mine waste dump. Using ten geogrids at a spacing of 1 m, the slope angle can be increased up to 60° with factor of safety of 1.4.

Faulting and Effects of Associated Shaking at Pisgah Crater Volcano Caused by the 16 October 1999 Hector Mine Earthquake (Mw 7.1), Central Mojave Desert, California

A 240-m-long zone of left-stepping fractures and scarps was mapped on 23 and 24 October 1999 on the east flank of the main cinder cone at Pisgah Crater volcano about halfway between the north end of the surface rupture, as mapped by other investigators, and highway I-40. The Pisgah Crater fractures are faults, not slump features, although undoubted slumps and shallow slides are present and abundant nearby. The free faces of the scarps range from 10 to 80 cm high; evidence of strike-slip was not observed. The scarps are at the base of an erosion-scarred, 2-m-high bench in the cone slope, that suggests the cone has been faulted previously. Indicators of strong motion associated with the Hector Mine earthquake include shattered earth and tossed ground, extensive collapse of oversteepened quarry slopes, and slumping of waste dump slopes, quarry cuts, and gully banks. A 1000-kg boulder that rested on a nearly flat surface was displaced 10 cm southward from its original position within its socket. Extensive sand slips on angle-of-repose slopes, expulsion of dust and silt from compacting cinders, local collapse of lava tubes, and dislodgment of precariously balanced boulders from quarry faces were also seen. Taken together, our observations suggest that strong motion associated with the Hector Mine earthquake on Pisgah Crater was nearly thrice the 0.33 g measured elsewhere by other investigators.

Effect of dynamic action during waste disposal on waste dump slope stability (in Serbo-Croat) : Obradovic, R Rud Glas, V18, N4, 1979, P5–8

Effect of dynamic action during waste disposal on waste dump slope stability (in Serbo-Croat) : Obradovic, R Rud Glas, V18, N4, 1979, P5–8