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Zoucheng, China

Huang Z.,China University of Mining and Technology | Jiang Z.,China University of Mining and Technology | Zhu S.,China University of Mining and Technology | Wu X.,China University of Mining and Technology | And 2 more authors.
Engineering Geology

In this study, in situ water injection tests and numerical modeling in conjunction with core logs and television image measurements were applied for an investigation of the hydraulic properties of the rock mass around underground excavations. The aim of our work was to investigate the influence of rock structure and water pressure on the hydraulic conductivity of the rock mass around underground excavations. Thus, water injection tests were conducted in four boreholes that were drilled in the rock mass in underground tunnels in China. Seepage connection initiation and steady state seepage were proposed to identify the seepage evolution course within the rock mass by combining the results of pressure and hydraulic conductivity. Generally, hydraulic conductivity is strongly related to rock structure and water pressure. The results also revealed that a rearrangement of rock structure would occur in the damage zone, resulting in an increase in hydraulic conductivity of nearly one to several orders of magnitude. The results from the modified numerical model showed that the pore water distribution and the groundwater inflow rate are affected by both the hydraulic conductivity and the thickness of the damage zone and they are influenced more by the thickness of this zone. © 2016 Elsevier B.V. Source

Huang Z.,China University of Mining and Technology | Jiang Z.,China University of Mining and Technology | Fu J.,China University of Mining and Technology | Cao D.,Yanzhou Coal Mine Co.
Arabian Journal of Geosciences

Hydraulic conductivity is an important hydrogeological parameter and is difficultly measured by laboratory experiments. In order to obtain the effective hydraulic conductivity of deep low-permeability rock and to study the water flow behavior within the rocks, in situ water injection experiments were employed in a deep underground tunnel. The applicability of Darcy's law is discussed as well. The study results show that Darcy's law may still be applicable for the initial determination of hydraulic conductivity for a partial transitional flow of water injection experiments, which retains linear relationship between pressure and flow rate. Water flow behavior in the rock experiences the initial stable phase, the increase phase, and the late stable phase in general but also has distinct flow properties due to the different characters of rocks. Hydraulic conductivity change with differential injection pressure can be divided into two phases, i.e., approximated constant hydraulic conductivity values which can be considered as the hydraulic conductivity of the rock in the initial flow phase and its effective value jump in the flow mutation phase caused by hydraulic fracturing. © 2014 Saudi Society for Geosciences. Source

Xiang P.,University of Science and Technology Beijing | Ji H.,University of Science and Technology Beijing | Wang J.,University of Science and Technology Beijing | Li W.,Yanzhou Coal Mine Co.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering

In order to evaluate the fault disturbance effect caused by exploitation, the concept of coulomb failure stress of tectonic earthquake fault has been introduce, the dynamic model of coulomb disturbance stress changes in fault plane caused by mining disturbance is established, and characteristics criterion of disturbance effect caused by exploitation is advanced. The characteristics criterion includes stress criterion, area criterion and gradient criterion expressed by coulomb stress changes. The higher the level and gradient of coulomb disturbance stress and the greater the distribution range, the bigger the potential risk of triggering dynamic disaster. On the basis of this theory combining with numerical simulation technology, the fault disturbance effect during coal exploitation in Baodian mine is analyzed, the results of which is roughly tallying with the actual situation. ©, 2015, Academia Sinica. All right reserved. Source

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