Abstract
In order to overcome the support difficulty of serious floor heave caused by rock burst, with the floor heave of ventilation roadway in Hegang Xing An Coal Mine as the engineering background, the treatment scheme of the concrete-filled steel tube corner pile and floor grouting is put forward. Based on the solution of the slip line field under plane strain condition, the mechanical model of the slip-type floor heave is established, and the formula for calculating the critical failure depth of the roadway floor and the minimum support depth of the corner pile is derived. Through numerical analysis and similar model tests, the deformation and stress distribution of surrounding rock under the support of the corner piles are studied, and the force law of the pile under high horizontal stress is analyzed. The results show that, compared with the floor corner anchor, the floor corner pile + floor grouting support scheme can significantly improve the mechanical properties of the floor rock mass, and the plastic slip line of the floor plate part can be cut by corner piles, which effectively controls the deformation of the floor plate under high horizontal stress; the length and inclination angle of the corner pile have a great influence on the support effect. In the on-site treatment scheme, 1.1 times the calculated length of pile should be selected. The results of a similar model and field test show that the corner pile is effective in controlling the deformation of roadway floor and two sides.
Highlights
Among the problems in deep mining, the nonlinear mechanical phenomena caused by high ground stress have attracted the attention of many scholars at home and abroad [1]
When the roadway was supported by floor corner pile, only 13 d was used to converge to the stable value, and the floor drum volume was stabilized to about 200 mm, which was close to the numerical analysis results
Based on the sliding line field solution of plane strain and using Mohr-Coulomb strength theory, the critical failure depth of roadway floor under the action of horizontal stress and the formula for calculating the minimum length of floor corner pile are derived, which provides a theoretical basis for the design of floor corner pile
Summary
Among the problems in deep mining, the nonlinear mechanical phenomena caused by high ground stress have attracted the attention of many scholars at home and abroad [1]. Under the action of high horizontal stress, various obvious large deformation phenomena appear in surrounding rock of roadway. According to the model test conducted by Yaodong et al [2], the slippage type floor heave is caused by the flow deformation of fractured rock mass under high horizontal stress and the slip of surrounding rock under high stress parallel to bedding. Kang et al [7] proposed the combined support method of grouting at floor plate and placing anchor bolts at floor corner and solved relevant construction problems. Is study is based on previous studies of sliding type floor heave under high stress, combined with the mechanical properties of CFST and the supporting method of CFST pile with floor corner plus grouting for floor plate is proposed. Based on the theory of slip field, the supporting mechanism of floor corner pile under typical stress field is analyzed, and its supporting effect is verified by the field test and a similar model test
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