RESEARCH AND ANALYSIS ON STABILITY OF BOLT REINFORCED TUNNEL IN ANISOTROPIC LAYERED ROCK MASS WITH LOW INCLINATION ANGLE STRATIFICATION

摘要

Wide contribution of layered rock mass cannot be avoided in underground construction.Based on the Gonghe tunnel in Yuxiang Highway,the monitoring to the surrounding rock and systemic bolts reveals that the tunnel lies in rock mass with bias pressure.In order to probe into the failure form and the reinforcing way,a physical model for layered rock mass with low inclination angle 22.5° is made adopting elasto-brittle simulated material which is developed independently.Loading through the large scale real triaxial geotechnical engineering testing machine,the configuration trait of secondary stress and failure mechanism of layered rock mass tunnel are presented.Various bolt reinforcing effects present in various place via the strain in surrounding rock,inner video,failure configuration around the tunnel and developed FLAC program,especially based on the strain configuration along the full length of bolt in the model.The test provides a quantitative evaluating index for safety storage with overload coefficient.The failure propagation in the test is consistent with the practical tunnel and the monitor of bolts which validates the anisotropic rock mass model and provides a foundation for the research on reinforcing mechanism and reinforcing design of tunnels in layered anisotropy rock mass.