Height Detection and Analysis of Water Flowing Fractured Zone of Coal Face

Taking 91105 working face as the research object, the observation method of water flowing fractured zone and the layout of mining holes were determined by analyzing the field geological structure. It was shown that the fractured zone height and the ratio given by the measured method were 52.33 and 12.46, respectively. By the numerical simulation method with the software of UDEC, the fractured zone height and the ratio were 42.5 and 10.12. By comparison of measured height data and UDEC numerical simulation, there were some differences between the measured height and the calculated results of UDEC numerical simulation method. The method of simulation can be used as the technical basis for the design of waterproof coal pillar in the future.

Hydrogeochemical Studies in Drought Scenarios: Canelones, Uruguay Case Study

The water scarcity in quality and quantity is becoming more noticeable and an urgent concern around the world. In Uruguay, these issues become exacerbated by the need to obtain drinking water in coastal areas, influenced by the climate change. Basic and structural geologies are strong conditioners in heterogeneous coastal aquifers. The objective of this study is to characterize the hydrochemistry of the fractured aquifers after having identified the main bearing fractures and the causes of aleatoreous water scarcity and quality problems, for hydric resources sustainable management. Identification of water bearing fracture, hydrogeochemical analysis and water quality evaluation are specific objectives. Some strategies were performed: 1) a base map in QGIS Software;2) fracture photointerpretation;3) geological correlation;4) statistical analysis of the background geochemistry data;5) ions analysis of strategically located wells. There were found water bearing fractures corresponding to 28 m3/h maximum flow rate for the NW-SE and 12 m3/h maximum flow rate for the NE-SW fracture direction, respectively. Besides, there could be a problem related to the high Sodium (Na) and Chloride (Cl) levels. In this respect, having previous data from 25 well samples, ions geochemical analysis has been carried out for 14 wells from Costa Azul and surrounding to have a first approach about the possible cause for the high values of Na (max. 385 mg/L) and Cl (max. 381 mg/L). The selected area for this study has a particular characteristic, because it corresponds to a heterogeneous fractured aquifer, which makes it difficult to catch water with enough flow rates and water quality to meet the population demand.

Optimum Calculation of Coal Pillars in Inclined Weathered Oxidation Zone

In the mining process of coal mine,waterproof coal pillars should be set between the weathered oxidation zone and the first mining face.In order to determine the reasonable upper limit of the first mining face of Hongyi Coal Mine,the waterproof coal pillar needs to be wide enough to resist the lateral hydrostatic pressure of the oxidation zone,and to ensure that the top plate aquifer does not run through the water guide crack zone,while also liberating as much stagnant coal as possible.In this paper,the first coal mine face’s waterproof coal pillar was calculated using conventional and optimized calculation methods,taking into account the dip angle of the coal seam,the height of the water-guide crack zone,and the rock shift influence zone,and finally the upper limit of the first face of Hongyi Coal Mine was determined.

Frost heaving and crack initiation characteristics of tunnel rock mass in cold regions under low-temperature degradation

Water freezing in rock fractures causes volumetric expansion and fracture development through frost heaving.This study introduces a novel analytical model to investigate how uneven freezing force and surrounding rock pressure influence fracture initiation,based on mass conservation,elasticity,and water-ice phase transition principles.A model for rock fracture initiation considering freezing temperature,uneven freezing expansion,in-situ stress,and lateral pressure was proposed based on fracture mechanics.Equations for stress intensity factors were developed and validated using the phase field method.The effects of rock elastic modulus anisotropy and critical fracture energy density on fracture initiation were also discussed.The results show that the values of KI and KII exhibit an upward trend as the freezing temperature,uneven expansion,in-situ stress,and lateral pressure increase.The uneven freezing expansion has the most significant influence on KI and KII values among these parameters.As the uneven freezing expansion coefficient increases to 0.5,the fracture initiation mode shifts from tensile fracture to shear fracture.As the lateral pressure coefficient increases to 1,the fracture initiation mode shifts from tensile fracture to shear fracture.Rock elastic modulus anisotropy causes fractures to propagate in a clockwise direction,forming a'butterfly'pattern.Critical fracture energy density an isotropy causes counterclockwise deviation in propagation direction,resulting in branching paths and an'H'-shaped pattern.