Abstract
Grouting reinforcement plays an important role in repairing fractures and improving the strength of the surrounding rock. To address practical engineering challenges such as caving and chip off-falling of surrounding rock in deep roadways, normal splitting was adopted to prefabricate fractures on rock samples gathered from underground coal mines. This was done to better match the rock fracture specimen with actual conditions. Based on the elementary unit of a fracture surface, systematic experiments were conducted on the tensile properties of rock fractures after grouting reinforcement, and the shear properties were studied after considering the presence of gas. As per the results, the tensile strength of rock fractures increased with the increase in viscosity of grout, but the overall tensile strength was relatively low. The overall tensile effect of surrounding rock was improved less by grouting approach. When the presence of fracture gas in grouting was considered, the peak shear strength of fractures after grouting was 8.34–29.9% less than that without considering the fracture gas. The cemented pore surface produced by unsaturated cementation in the grouting reinforcement was the main cause of reduction in cohesion and frictional angle of rock fractures. The conclusions of this study have great significance for guiding engineering grouting and evaluating the grouting effect.
Highlights
Coal is one of the most important energy sources in the world
Research on grouting reinforcement mechanisms has mostly focused on changes to the macro-mechanical parameters and physical properties of the rock mass after grouting, and there is a lack of research on the scale of the fracture surface [8,9,10,11,12]
Based on scientific problems faced in the engineering field and the elementary unit of rock fracture, the tensile properties of rock fractures after grouting and the shear properties of rock fractures, considering the presence of gas, were systematically studied using coal mine rock samples after processing
Summary
Coal is one of the most important energy sources in the world. To achieve a sustainable exploitation of coal, mines around the world have entered the stage of deep-buried mining. For deep surrounding rock with high stress and fracture development, grouting reinforcement can significantly improve the structure and mechanical properties of fractured rock masses [1,2,3,4]. The direct effect of grouting reinforcement is to change the mechanical properties of the fractured surface. It is known that in the grouting process, gas presence (mash gas and air) in fractured rock affects the grouting diffusion and, impacts the reinforcement effect [16,17]. Based on scientific problems faced in the engineering field and the elementary unit of rock fracture, the tensile properties of rock fractures after grouting and the shear properties of rock fractures, considering the presence of gas, were systematically studied using coal mine rock samples after processing. The corresponding mechanical properties and rules were obtained, providing guidance for relevant issues in engineering
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