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Abstract
It is important to have a clear understanding of the creep characteristics of water-rich soft rocks under a dynamic load and the evolution of cracks because soft rock roadways in deep mines are very sensitive to disturbances, and instability and damage can easily occur under the impact of disturbances such as mining and blasting. In this study, a self-developed disturbed creep test bench was used to conduct graded loading creep disturbance tests on mudstone specimens with different moisture contents. The results show that an increase in the moisture content leads to a significant increase in the creep failure strain of mudstone, and the accelerated creep rate is greatly accelerated. Moreover, as the moisture content increases, the type of mudstone creep disturbance failure gradually changes from accelerated creep failure to disturbance failure. By analyzing the acoustic emission (AE) characteristics of the mudstone creep disturbance tests, it was found that the increase in the moisture content greatly weakens the AE count and the accumulated energy. In each stage of disturbance, the AE signals jumped, and the stability was restored at the end of the disturbance. As the load increased, the specimen entered the accelerated creep stage, the AE signal increased exponentially, and the internal cracks expanded rapidly until failure occurred. It is of great significance to carry out creep disturbance experiments and to analyze the evolution of the internal cracks in specimens with different moisture contents to maintain the long-term stability of deep soft rocks.
Highlights
With the depletion of shallow mineral resources, coal mining is moving to deeper depths [1]. e occurrence environments of deep rock masses are complex
They are under a combined stress state consisting of a static load and dynamic disturbances, and the stress is close to the strength limit
The research on the creep characteristics of rock masses and the law of crack development under a static load has been relatively sufficient. Whether it is combined with the actual needs of a project or of disaster warning and prediction, the study of the creep characteristics of a rock mass must consider the impact of a dynamic disturbance. us, in this study, an independently developed rock rheological disturbance test system was used to conduct graded loading creep disturbance and acoustic emission (AE) tests on mudstone specimens with different moisture contents. e soundabsorbing cotton was covered with a sound insulation board to avoid the interference of the perturbation on the AE signal. e characteristic AE parameters were used to analyze the creep disturbance process and the crack evolution in mudstone specimens with different moisture contents
Summary
With the depletion of shallow mineral resources, coal mining is moving to deeper depths [1]. e occurrence environments of deep rock masses are complex. CT and AE equipment are often used to study the creep of a rock mass under constant stress, and there is less research on the creep characteristics of rock masses under dynamic load disturbance. The research on the creep characteristics of rock masses and the law of crack development under a static load has been relatively sufficient. Whether it is combined with the actual needs of a project or of disaster warning and prediction, the study of the creep characteristics of a rock mass must consider the impact of a dynamic disturbance. E results of this study provide a useful reference for followup research on soft rock roadway support in deep engineering and soft rock creep and rupture triggered by disturbances such as excavation and blasting
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