Display omitted
•Laboratory testing and quantification of soil erosion.•Effects of topography on runoff, sediment yield and water and soil loss regulations.•For sediment yield and water and soil ...loss, topography has the greatest influence.•Anti-S-shaped slopes exhibit favorable erosion resistance.
Due to frequent severe mining activities and globally destructive extreme storms, soil and water loss in open-pit coal mine dumps is extremely serious. To investigate the effect of topography on soil erosion, rainfall with a constant intensity of 1.50 mm·min−1 was conducted on topography models for 60 min. We investigated the effects of 4 topographies (straight slope, concave slope, S-shaped slope and anti-S-shaped slope) and 4 slope gradients (20°, 25°, 30° and 35°) on runoff, sediment yield, and soil and water loss. The results show that the 25° slope gradient was not conducive to infiltration, but the S-shaped slope was favorable. The runoff and sediment yield increased rapidly, then fluctuated upward in a certain range and eventually stabilized with increasing rainfall duration. With increasing slope gradient, the total runoff decreased exponentially, the total sediment yield decreased linearly, and the total amount of water and soil loss declined continuously. The initial runoff time results exhibited the order of anti-S-shaped slope > straight slope > concave slope > S-shaped slope, but the stable runoff size satisfied the S-shaped slope > straight slope > concave slope > anti-S-shaped slope. The results of the significant degree of influence of topography on sediment yield and water and soil loss exhibited the order of anti-S-shaped slope > S-shaped slope > straight slope > concave slope and S-shaped slope > straight slope > concave slope and anti-S-shaped slope. The effect of slope gradient on soil humidity and runoff was more significant than that on topography and their interaction (p < 0.001). Nevertheless, for sediment yield and water and soil loss, topography had the greatest influence (p < 0.001). Notably, the total amount of water and soil loss on the anti-S-shaped slope was relatively minimal.
In order to study the stability control mechanism of a concave slope with circular landslide, and remove the influence of differences in shape on slope stability, the limit analysis method of a ...simplified Bishop method was employed. The sliding body was divided into strips in a three-dimensional model, and the lateral earth pressure was put into mechanical analysis and the three-dimensional stability analysis methods applicable for circular sliding in concave slope were deduced. Based on geometric structure and the geological parameters of a concave slope, the influence rule of curvature radius and the top and bottom arch height on the concave slope stability were analyzed. The results show that the stability coefficient decreases after growth, first in the transition stage of slope shape from flat to concave, and it has been confirmed that there is a best size to make the slope stability factor reach a maximum. By contrast with average slope, the stability of a concave slope features a smaller range of ascension with slope height increase, which indicates that the enhancing effect of a concave slope is apparent only with lower slope heights.
Reliable determination/evaluation of the rock deformation can be useful prior any structural design application. Young’s modulus (
E
) affords great insight into the characteristics of the rock. ...However, its direct determination in the laboratory is costly and time-consuming. Therefore, rock deformation prediction through indirect techniques is greatly suggested. This paper describes hybrid particle swarm optimization (PSO)–artificial neural network (ANN) and imperialism competitive algorithm (ICA)–ANN to solve shortcomings of ANN itself. In fact, the influence of PSO and ICA on ANN results in predicting
E
was studied in this research. By investigating the related studies, the most important parameters of PSO and ICA were identified and a series of parametric studies for their determination were conducted. All models were built using three inputs (Schmidt hammer rebound number, point load index and p-wave velocity) and one output which is
E
. To have a fair comparison and to show the capability of the hybrid models, a pre-developed ANN model was also constructed to estimate
E
. Evaluation of the obtained results demonstrated that a higher ability of
E
prediction is received developing a hybrid ICA–ANN model. Coefficient of determination (
R
2
) values of (0.952, 0.943 and 0.753) and (0.955, 0.949 and 0.712) were obtained for training and testing of ICA–ANN, PSO–ANN and ANN models, respectively. In addition, VAF values near to 100 (95.182 and 95.143 for train and test) were achieved for a developed ICA–ANN hybrid model. The results indicated that the proposed ICA–ANN model can be implemented better in improving performance capacity of ANN model compared to another implemented hybrid model.
In order to study the deformation and failure mechanism of the roof in end slope mining, a mechanical model of the two-end fixed beam was established, combined with the theory of elasticity to derive ...the calculation equations for the stress and displacement of the roof, and to consider the effect of the extrusion of the overlying weak rock layer of the rib pillar on the deformation of the roof, and finally, the analysis obtained the stress distribution and deformation law of the roof. The research shows that the distribution of normal stresses in the roof is parabolic with a secondary axisymmetric distribution at the center of the roadway, and the maximum tensile stress is at the center of the bottom of the roadway. The maximum tensile stress and the maximum shear stress on the roof increase continuously with the increase of mining progress. The location of the middle of the bottom surface of the roof first shows tensile failure, and then gradually changes to shear failure at the contact location with the coa
ln-situ experiments were conducted to investigate the mechanical properties of the soil-rock mixture in the internal dump of the Shengli #1 Surface Coal Mine, China. Based on the experimental ...results, this study used comparative analysis and found that the shear strength of the soil-rock mixture in the dump was greater than the residual shear strength of the original rock. The results showed that the material presented in the dump as large blocks was the main factor affecting the strength of the soil-rock mixture, Numerical simulation was carried out for the analyses of three factors： different combinations of shear failure, rolling failure along with different large-block radius ratios, and mixture densities. The results illustrated that the cohesion and angle of internal friction of the soil-rock mixture are 12 kPa and 32.26°. However, in some cases the bench angle in the dump was controlled by a coupling relationship of rocks in the material. Finally, the stability of a soil slope showed a linear relationship with the large-block radius ratio and the bulk density.
To promote the sustainable exploitation of open-pit coal resources, waste is used as backfill material to realize the comprehensive utilization of solid waste mine resources. We proposed a mining ...method that is a combination of the highwall mining and filling mining methods. Cemented paste backfill (CPB) samples were prepared with high-clay-mineral-content marl particles as aggregate and normal Portland cement, sulfoaluminate cement and gypsum as cementing materials. The physical and mechanical properties and microstructural evolution of CPB with different binder ratios under wetting–drying cycles were measured. The results showed that the CPB with 0–3 wetting–drying cycles underwent shear and tensile coalescence, and that with 4–10 cycles underwent shear coalescence. The unconfined compressive strength (UCS) and elastic modulus (EM) decreased exponentially with increasing number of wetting–drying cycles but decreased exponentially and cubically with increasing porosity, respectively. The EM is more sensitive to gypsum content than the UCS. CPB deterioration was divided into an initial deterioration stage and a secondary deterioration stage. The evolution curve of the total damage variable presents an ‘S’ shape, with an initial damage stage, an accelerated damage expansion stage, a decelerated damage expansion stage and an end damage stage. The research results provide a basis for improving the recovery rate of resources under highwall conditions, and the extensive utilization of stripping materials, and promote the coordinated development of coal resource exploitation and environmental protection.
In order to study the stability difference of dump slope under different pore water pressure redistribution and evaluate the stability, according to the actual groundwater level distribution of a ...mine dump from August to September, the influence mechanism of water pressure redistribution on slope stability is analyzed. SLOPE/W module is used to simulate the slope stability difference and safety factor variation under different pore water pressure distribution. The results show that the redistribution of pore water pressure will change the pore space in the slope, accelerate the infiltration, and weaken the slope of waste dump in different degrees. With the decrease and expansion of the negative pore water pressure distribution range, the matrix suction of the slope changes and the safety factor first decreases and then increases. When the slope safety factor increases to 1.421, the groundwater level decreases by 30 m. It is close to the basement as a whole and will no longer affect the slope stability of wast
A clear understanding of landslide mechanisms and stability analyses is of great significance for landslide monitoring, prediction, and control. A large-scale end wall landslide occurred and its area ...reached 47,752 m
2
on August 7–20, 2020, in the Manglai open-pit coal mine, China. In this paper, the engineering geological survey, mechanical test, large-deformation finite element numerical method, limit equilibrium method and analytical formula are used to analyze how the groundwater level rise caused this end wall failure and landslide. The engineering geological conditions, hydrogeological conditions, landslide activity signs and physical and mechanical parameter calibration of the sliding mass are investigated in detail and tested. Three-dimensional and two-dimensional numerical models of slopes are established, and an analytical formula calculation method to calculate the factor of safety (FoS) is proposed when sliding cracks are located on the top and toe of a slope. The results indicate that the fault fracture zone, soft strata, continuous heavy rainfall, and groundwater were the main contributors to this landslide. The three-dimensional numerical calculation results are consistent with the deformation and failure process of the slope observed in the field, which shows a retrogressive progressive failure mode. The calculation results of SLOPE/W and the analytical formula are consistent; i.e., when the groundwater level rises to +950, the stability of the end wall reaches the critical stability state. With the passage of time, the creep of the sliding surface accelerates until the entire end wall landslide.
PDF
