Explore the vast range of titles available.

A method of evaluating the risk of floor water inrush using principal component logistic regression analysis (PCLRA) and an improved analytic hierarchy process (IAHP) is presented. The approach was validated by a case study at the Yangcheng coal mine in Shandong Province, China. First, the risk assessment index of floor water inrush was determined based on geological and hydrogeological conditions of the study area. Then, a comprehensive evaluation model (CEM), combining PCLRA with IAHP, was constructed to determine the comprehensive weight of each water-inrush evaluation index. Finally, water-inrush risk zoning was determined with GIS. The results show that the CEM, compared with the water-inrush coefficient method (WICM) traditionally and commonly used in China, has higher fitting accuracy and more detailed division of water-inrush risk areas. This method not only follows the observations in reality, but also fully considers the relative importance of water-inrush evaluation indices. The results can provide a theoretical basis for the safe mining of coal seams above confined groundwater.

This paper presents an investigation on the effect of grouting into multi-bed-separation to control mining-induced surface subsidence. In the overburden without obvious thick-and-hard strata for generating large-scale bed separation, overburden grouting is carried out by increasing the number of boreholes and grouting strata. The scale model test, numerical simulation, and field measurements are used to study distribution and process of bed separation and to compare the overburden failure with surface subsidence due to pre- and post-overburden grouting, with a case study of the Qi’nan Coal Mine, Anhui Province, China. The scale model test and numerical simulation results of the overburden grouting process are in close agreement with those obtained from the field measurements. Filling masses with different diffusion radii are commonly formed in the different bed separation, which are overlaid to control the surface subsidence. It is proven that overburden grouting can successfully mitigate overburden failure and subsidence without obvious hard strata and bed separations. This provides an effective and cost-efficient approach for addressing the surface subsidence and overburden deformation problems due to mining.

This paper presents an investigation on the effects of intermittent cut-and-fill mining on the overburden failure under sand aquifers. In the intermittent cut-and-filling method, the panel is divided into long pillars, and then entries in every long pillar into a narrow strip; every narrow strip is then cut and backfilled. Field measurements, scale model tests and numerical simulations are used to compare overburden failure and subsidence due to three mining methods: intermittent cut-and-fill mining, longwall excavation and continuous filling. These methods were applied in a case study of the Taiping Coal Mine, in Shandong, China. The results of the numerical simulation and scale model testing reveal that the height of the maximum caving and water-conducting fractured zones, and the maximum subsidence due to intermittent cut-and-fill mining are much smaller than those with the use of longwall excavation and continuous filling and well verified by the field measurements. Additionally, the numerical simulation results of the stress distribution and variation during intermittent cut-and-fill mining are in close agreement with those of the field measurements. It has been proved that the intermittent cut-and-fill mining can successfully mitigate the overburden failure and subsidence, which contribute to preventing water and sand inrush into coal mines under sand aquifers. This provides a less costly and more effective approach to address surface subsidence and mine caving problems.

The Ili River Valley in Xinjiang, China, is a typical seasonal frozen area where loess landslide disasters have become increasingly common during the freeze–thaw periods in recent years. This study analyzed the macroscopic mechanical strength and microstructure changes of the Ili loess under different freeze–thaw cycles (FTCs) through the post-freeze–thaw triaxial compression test on the unsaturated soil in laboratory. Apart from the scanning electron microscopy (SEM), and the nuclear magnetic resonance (NMR), the macro–micro correlation analysis and the cluster-principal component analysis were applied for the theoretical discussion. The results indicated that the cohesive force of the loess exhibits an initial decreases, followed by the increases, and eventually keep stable after various FTCs, while the internal friction angle showed the opposite developing trend before the final constant. Similar to the strong correlation between the cohesive force and the particle abundance, the internal friction angle is also closely related to the abundance and orientation fractal dimension of the loess particles. However, the principal component analysis results showed that cohesive force strongly correlates with the average maximum pore size and the pore size fractal dimension, for which the internal friction angle most strongly affected by the average maximum particle size. The possible reason is that the extracted principal components represent a class of microscopic parameters with the same or similar change trend, although there may be a certain offset between them. The mechanical deterioration of loess is attributed to the repeated frost heaving force and the migration potential caused by FTCs. The alterations of the microstructure accelerated the deterioration of the macroscopic mechanical properties of the loess, which further widens the understanding of the mechanism behind the deterioration of loess mechanical strength in the Ili River Valley under FTCs, and contributes to the prevention and management of the local landslide disasters.

Background Rock engineering systems face escalating threats from extreme climatic events and the complexities of deep engineering, necessitating robust resilience to withstand multi-hazard disturbances. Traditional methods, based on static equilibrium analysis, prove unsuited to address the dynamic, nonlinear interactions inherent in these systems. Objective This study proposes a resilience-oriented framework for rock engineering, emphasizing the system’s capacity to maintain or rapidly recover functionality following disturbances. The study proposes a conceptual model, evaluation method, and enhancement techniques to improve rock engineering resilience, based on the complex system science. Methods A unified disaster resilience management system is proposed, synergizing multi-field monitoring, risk assessment, and rapid recovery strategies. Three resilience-enhancing techniques are presented, including grouting reinforcement, resilient anchor support, and high-pressure anchor injection-spraying collaborative control, optimize stress redistribution and fracture resistance in rock masses. Results The framework redefines resilience as a quantifiable system property, enabling data-driven lifecycle management of geotechnical infrastructure. It provides actionable strategies to reconcile safety and sustainability in deep tunneling and slope stabilization projects. Conclusions By redefining resilience as a quantifiable system property rather than a qualitative goal, the framework enables data-driven lifecycle management of geotechnical infrastructure.

Water inrush disasters in geotechnical engineering are mainly caused by seepage in fractures, and curtain grouting is the most common method to block water flow. To ensure the efficacy of the water blocking curtain, it is necessary to study the slurry’s diffusion pattern. In this study, by means of laboratory experiments and theoretical deductions, the grout diffusion morphology in fractures with the slurry-rock stress coupling effect is revealed, and the corresponding theoretical model is established. First, based on the failure of water-blocking curtain in a hydropower station in Yunnan Province, a four-level four-factor orthogonal table was set up, grouting experiments were conducted using the self-developed fracture grouting device, and the relationship between the main influencing factors and fracture deformation and grout diffusion distance was revealed. Then, based on the Bingham fluid constitutive model, fracture deformation equation and grouting model with flowing water, a new fracture grouting model considering the coupling effect of slurry-rock stress was established. Finally, based on the calculations and experiments, the morphology of slurry diffusion is described, thereby proving the validity of the new model.

A systematic method was developed to evaluate the risk of water inrush through a coal seam floor using the geographic information system (GIS) and the fuzzy set theory. The main geological and hydrogeological indicators that control water inrush were first considered using a fuzzy mathematics approach, in which fractal analysis was carried out to quantify the fault’s characteristics. The degree of membership was determined using GIS, the weight of every factor was considered by calculating the entropy in accordance with Shannon’s information entropy theory, and the level of risk of the evaluated object was derived using the maximum membership principle. The approach was validated by a case study at the Chensilou mine in Henan Province, China, where the aquifers that underlie an exploitable coal seam, II 2, were made impermeable by grouting. Data from Nov. 2014 to April 2016 shows that the risk of water inrush was reduced in Panel 2517 of the II 2 coal seam, that there were no serious disturbances in this panel and no groundwater inrush through the floor. This method can be a powerful tool for systematically assessing the risk of water inrush through the floor, since the influence of several factors can be quantitatively considered in accordance with the geological and mining conditions.

Backfill mining is an important means of ensuring the high efficiency and safety of the coal mining under thin bedrock and loose aquifers. Based on the case study of Taiping Coalmine, the theoretical analysis of entropy and numerical modeling methods are adopted to establish the visualization model of temporal–spatial cube of stress and displacement induced by the multiple layers backfill mining. Moreover, the quantitative characterization and measurement framework of symmetric KL-divergence is established based on information entropy and mutual information. The results show that: (1) The non-uniformity of stress and displacement is enhanced due to the multiple layers backfill mining, showing certain fluctuation characteristics. (2) The KL-divergence of stress to displacement is slightly greater than that of displacement to stress, and the hotspot distribution law of stress–displacement related efficiency is consistent with KL-divergence. (3) The hotspots of stress entropy and the gap between stress entropy and displacement entropy in multiple layers backfill mining decrease obviously. (4) Stress plays a main role in displacement, and displacement is a linkage response to stress due to the coordinated deformation. Multiple layers backfill mining results in an enhanced correlation degree and more chaotic state between stress and displacement. The results will provide engineering geological basis for optimal design and safe production of backfill mining under loose aquifers.

Glacial till deposits in the Greater Toronto Area (GTA) usually comprise fine-grained (clay and silt) and coarse-grained (sand, gravel, cobbles, and boulders) fractions, which are substantially heterogeneous in characteristics. Since coarse-grained fractions are too large to be tested in traditional laboratory equipment, the discrete element method (DEM) is applied in this study to simulate a series of large-scale biaxial tests to study the mechanical characterization of glacial till. This study is based on the results of comprehensive geotechnical investigations for the Eglinton Crosstown Light Rail Transit (LRT) Project in the GTA. The fine-grained till (clayey silt till) examined in this work is collected from the O’Connor Station site. The different proportions, gradations, and sizes of the coarse-grained fractions (gravel) with irregular random shapes and distributions are simulated. The analysis results indicate that the proportion of gravel influences the behavior and mechanical characterization of glacial till. The peak strength and initial modulus of the mixture gradually increase as the volumetric proportion of gravel increases to 30%. Beyond this percentage, the peak strength and initial modulus substantially increase. The failure mode of the sample changes from ductile to brittle with a volumetric proportion of gravel that is greater than 30%. In summary, when the volumetric proportion of gravel is limited to 30%, the gradation and size of the gravel only have a marginal influence on the mechanical characterization of the glacial till. However, a volumetric proportion of the gravel that exceeds 30% has significant impacts on the strength and deformation characteristics of glacial till.