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To study the fissure-stress evolution law of overburden rock in the process of working face advancing in the dual fault area. This paper took the geological occurrence condition and actual mining situation of working face 21,129 of Tucheng mine as the engineering background. The method of similarity simulation combined with field measurement was adopted. The evolution law of the stope fissure field, the stress variation trend of roof fault, and migration characteristics of overlying strata in the process of stope mining through dual faults were studied. The results showed that: Dual faults had a large effective area on the surrounding rock of the stope, the surrounding rock movement in the affected area was intense. When the working face advanced to the fault F2 area, the energy generated during the surrounding rock movement of the fault F2 was transferred to the fault F1, which intensified the activity of the rock in the fault F1 area. The activation of the fault F2 caused the fissures in the surrounding rocks of the fault F1 to expand further. The surrounding rock of the stope changed from a single-fault action mode to a double-fault joint action mode. According to the degree of development of cracks in the roof of the overlying strata, the stope’s different positions were sorted from large to small as follows: fault activated fracture zone > central dual fault zone > open-off cut zone > middle of the non-fault affected zone. The field measured data showed that the area affected by the dual fault was composed of “high-pressure area” and “low-pressure area.” The working resistance value of hydraulic support was higher than that of the non-fault affected area. The law of fracture development and distribution in overlying strata of stope in similarity simulation experiments were consistent with the law of roof pressure measured in the field.

Landslide hazard zonation plays an important role in safe and viable infrastructure development, urbanization, land use, and environmental planning. The Shafe and Baso catchments are found in the Gamo highland which has been highly degraded by erosion and landslides thereby affecting the lives of the local people. In recent decades, recurrent landslide incidences were frequently occurring in this Highland region of Ethiopia in almost every rainy season. This demands landslide hazard zonation in the study area in order to alleviate the problems associated with these landslides. The main objectives of this study are to identify the spatiotemporal landslide distribution of the area; evaluate the landslide influencing factors and prepare the landslide hazard map. In the present study, lithology, groundwater conditions, distance to faults, morphometric factors (slope, aspect and curvature), and land use/land cover were considered as landslide predisposing/influencing factors while precipitation was a triggering factor. All these factor maps and landslide inventory maps were integrated using ArcGIS 10.4 environment. For data analysis, the principle of logistic regression was applied in a statistical package for social sciences. The result from this statistical analysis showed that the landslide influencing factors like distance to fault, distance to stream, groundwater zones, lithological units and aspect have revealed the highest contribution to landslide occurrence as they showed greater than a unit odds ratio. The resulting landslide hazard map was divided into five classes: very low (13.48%), low (28.67%), moderate (31.62%), high (18%), and very high (8.2%) hazard zones which was then validated using the goodness of fit techniques and receiver operating characteristic curve with an accuracy of 85.4. The high and very high landslide hazard zones should be avoided from further infrastructure and settlement planning unless proper and cost-effective landslide mitigation measures are implemented.

The efforts made all over the world towards the fact of decreasing the environmental pollution have been enormously demanding now a days. Therefore the increase in caution towards a sustainable environment has restricted the use of materials which may have huge impact towards environment pollution. The geosynthetic is a cost-effective and corrosive resistant material which can be used in the most exposed conditions to mitigate the anticipated excessive settlement in case of soft soil. The present study investigated the behaviour of a geocomposite material in a layered soil system. Three types of geocomposite were manufactured by changing the tensile stiffness of the components viz. GCBX-40, GC-BX-60, and GC-BX80. The basic configuration of every geocomposite was same and was made by sandwiching a geotextile layer in between the two geogrid layers which have significantly improved the surface frictional resistance due to the increase in the surface cover ratio and also the improvement in the interlocking effect on the soil grains due to the geogrid layers on both sides. The various layouts of geocomposite were introduced in this study besides the general planar layout and it was found that the confinement effect was increased with in the soil layers. Therefore, the cohesion (c) between the soil grains and the frictional angle (ϕ) was modified due the increased confinement which not only improved the bearing capacity factor but the settlement reductions factor was also improved. The results revealed that the load carrying capacity was improved from 33.8 to 40.59% by using different types of geocomposite.

Expansive soils exhibit complex behavior associated with significant volume changes triggered by moisture variations induced by changes in environmental conditions. This type of process impacts on soil properties, such as shear strength, stiffness, and permeability. Also, cracks generally develop upon desiccation. There are still several gaps in the current knowledge in this area, particularly in relation to the factors that affect the shear strength of soils and control the formation of drying cracks. This paper focuses on the impact of some of these factors on crack formation and shear strength of an expansive soil mixture made up of 75% kaolin and 25% bentonite, % by mass. Three factors were considered in this research; soil structures (associated with different sample preparation methods), initial saturation, and textures at soil-base interface. Two laboratory series consisting of desiccation plate and soil-base interface shear tests were conducted. For each series, three types of soil specimens were prepared considering different preparation methods (with the associated different soil structures) and initial saturation conditions namely; slurries, fully-saturated compacted and unsaturated compacted specimens. Soil-base interface shear strengths were determined using four different interface textures; grooves oriented perpendicular to shear direction, spiral (circular) indentations, grooves aligned parallel to the shear direction, and smooth surface. For the desiccation plate tests, two types of textures were adopted for the plate-base, namely, circular indentations and smooth to study constrained and free shrinkage conditions, respectively. Results of desiccation tests revealed that cracks developed in the constrained plate (e.g., with circular indentations), whereas no cracks were observed under free displacements conditions (e.g., smooth surface). The direct shear tests revealed that the soil-base interface shear strength is strongly affected by the specimen moisture, soil structure and the direction of the shearing  respect to the grooves orientation. For the three set of experiments conducted (i.e., slurry, compacted-saturated, compacted-unsaturated), the highest strength was found for the surface with groove oriented perpendicular to shear direction and the lowest one for the smooth plate. The shear strength associated with the circular-grooves base is in-between those ones observed for the plate with grooves oriented perpendicular and parallel to the shear direction.

The primary objective of bioreactor landfill is to achieve adequate and rapid distribution of moisture in landfilled municipal solid waste (MSW) to accelerate the anaerobic biodegradation of the organic fraction within MSW. A horizontal trench system (HT) is commonly adopted for leachate distribution in MSW under pressurized conditions. However, this approach should be implemented carefully due to the potential instability of landfill slopes that comes from the generation and distribution of excessive pore fluid pressures. In this study, HT design charts are presented that determine the optimal location of horizontal trench systems from the side slope (i.e., minimum lateral setback distance) under continuous leachate addition with maximum applied injection pressures, for which the landfill slopes remain stable [factor of safety (FOS) where FOS ≥ 1.5]. Use of any higher injection pressure and/or shorter lateral setback distance of HT than the one presented in the design charts would result in an unacceptable design of the bioreactor side slope (FOS < 1.5). The design chart was developed based on a parametric study that used a numerical two-phase flow model that involved different slope configurations and landfill waste depths. MSW heterogeneity and anisotropy, as well as unsaturated hydraulic properties, were taken into consideration in these simulations. Transient changes in pore water and gas pressures due to leachate recirculation were accounted for dually in the slope stability computations. The importance of these design charts is illustrated using a practical example. Site-specific conditions and the expertise and prior experience of a designer or operator must also be adequately considered and utilized with the design charts presented here for the safe design of a horizontal trench system in a bioreactor landfill.

Throughout the world, subsurface contamination has become a widespread and pervasive problem. Toxic chemicals such as heavy metals and organic compounds are commonly used in a myriad of industries. However, largely through inadvertent or accidental release, these chemicals are presently polluting sites across the United States. In order to protect public health and the environment, further pollution must be prevented and sites with existing contamination urgently need remediation. Unfortunately, remediating subsurface contamination has proved to be a daunting task. Heavy metals and organic compounds often coexist and their distribution within the subsurface is highly dependent on particle and macro-scale heterogeneities. Vast resources have been invested to develop efficient remediation technologies, yet very few of these technologies have been successful. In-situ remediation is often preferred due to minimal site disturbance, safety, simplicity, and cost-effectiveness. The effectiveness of in-situ remediation technologies depends largely on the contaminant chemistry and subsurface heterogeneities (including particle-scale heterogeneities such as fine-grained soils, soils with reactive minerals, and/or soils rich in organic matter as well as macro-scale heterogeneities such as irregular soil layers and/or lenses). Under such heterogeneous conditions, integrated electrokinetic remediation technology has great potential. As a safe and economical remedial option for so many contaminated sites, the application of integrated electrokinetic remediation offers enormous public health, environmental, and financial benefits.

This paper first analyzes the factors influencing the safe thickness and the broken mechanism of rock between a tunnel and the surrounding concealed caves on the Cheng-gui railway line. Then, based on the analysis of broken mechanism, a comprehensive numerical analysis method, which is based on the Yujingshan Tunnel project, is put forward. This method of analysis is simulated using FLAC3D software to perform three-dimensional numerical simulations for different positions, providing the basis for the subsequent safe thickness analysis and construction scheme design. Actual monitoring and computational results shows the safety distance of the range of the tunnel’s diameter, which proved the rationality and effectiveness of the calculation of the safe thickness between the tunnel and the surrounding concealed caves.

Longwall coal mining causes a large scale of subsidence in both overlying strata and ground surface. No matter where subsidence or deformation happened, its damaging effects to underground mining work or surface infrastructures are not anticipated. To accurately predict surface subsidence over the mining area, surface subsidence prediction models based on influence function method are developed. Based on the surface subsidence model, in this paper, a prediction model for overlying strata movements is developed with innovatively optimizing three key parameters used for setting the boundary condition. A load is derived using the beam theory with the simple overlying strata model, which is important for getting the radius of major influence, one of the three key parameters. Many features of progress subsidence are reproduced in the model and finally found to fit reasonably well with numerical simulation results using the same geological parameters. The modelling study reveals that the newly proposed subsurface model is flexible and versatile to represent the subsurface subsidence profile under various possible conditions. The key strata, especially the hard rock strata, act like an elastic beam and can overhang the load from above strata so that the displacement of rock mass or stress distribution in strata will be drastically changed when close to key strata. The proposed subsurface subsidence prediction model discloses some basic laws of overlying strata subsidence with the mining of coal seam.