Abstract
To clarify the process of stress change and plastic zone evolution of square roadways under high-stress conditions, the rotational square expansion plastic zone evolution model of square roadway was established by theoretical analysis, numerical simulation, and engineering verification. The shear slip impact stress criterion of square roadway based on complex variable function theory was studied, and the law of surrounding rock stress distribution, plastic zone expansion, elastic energy density, local energy release rate (LERR), and total energy release of square roadway were analyzed. The results show that the compressive stress is concentrated in the four corners of the roadway after the roadway excavated and transfers with the change of plastic zone. Main shear failures start from the four corners and develop in a rotating square shape, forming square failure zones I and II. The square failure zone I is connected with the roadway contour and rotated 45°. The square failure zone II is connected with the square failure zone I and rotated 45°. When the original rock stress is low, the surrounding rock tends to be stable after the square shear slip line field formed. When the original rock stress is high, the shear failure of the surrounding rock continues to occur after the square failure zone II formed, showing a spiral slip line. Corners of the square roadway and square failure zones I and II are the main energy accumulation and release areas. The maximum elastic energy density and LERR increase exponentially with the ratio of vertical stress to uniaxial compressive strength (Ic). When square corners of the roof are changed to round corners, the plastic zone of the roof expands to form an arch structure. The maximum elastic energy density decreases by 22%, which reduces the energy level and possibility of rock burst. This study enriches the failure mechanism of roadway sliding impact. It can provide a basic theoretical reference for the design of the new roadway section and support form based on the prevention of rock burst.
Highlights
Decheng Ge,1 Fuxing Jiang,1 Cunwen Wang,2 Yang Chen,3 Chunyu Dong,2 Sitao Zhu,1 Zhaoyi Wang,4 and Fei Han2
To clarify the process of stress change and plastic zone evolution of square roadways under high-stress conditions, the rotational square expansion plastic zone evolution model of square roadway was established by theoretical analysis, numerical simulation, and engineering verification. e shear slip impact stress criterion of square roadway based on complex variable function theory was studied, and the law of surrounding rock stress distribution, plastic zone expansion, elastic energy density, local energy release rate (LERR), and total energy release of square roadway were analyzed. e results show that the compressive stress is concentrated in the four corners of the roadway after the roadway excavated and transfers with the change of plastic zone
The rotational square expansion plastic zone evolution model of square roadway was established, and the stress criterion of shear slip impact of square roadway based on complex function theory is given
Summary
After the formation of square failure zone II, the stress distribution at the corner of square failure zone II changes due to the reaction of the destroyed coal and rock mass in the roadway. When the roadway failure does not form square failure zone I, the plastic zone is small and will not form a largescale rock burst. When the roadway failure forms square failure zone II, the overall weak block of the surrounding rock further increases, which is easy to form large-scale roadway rock burst. Average stresses of the slip line in square failure zone I and square failure zone II are equal because linear intervals are connected. When the stress state of the surrounding rock breaks through the limit equilibrium state, the shear slip impact occurs in the corresponding region
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