Analysis on the Parameters of Bolt Pre-reinforcement in the Face of Shallow Buried Soft Surrounding Rock Tunnel
When a large section shallow buried tunnel is excavated in soft surrounding rock,the core soil in front of the face is often in a transient stable or unstable state.If the core soil in front of the tunnel face is not properly treated,it can cause instability of the core soil.Therefore,it is necessary to use glass fiber an-chor rods for pre-reinforcement of the core soil.Combined with a tunnel project in Georgia,adopting the con-cept of new Italian law,the reinforcement length l(5 working conditions)and reinforcement density β(7 working conditions)of bolts in the face of tunnel with full face excavation in shallow soft surrounding rock are optimized and analyzed with FLAC3D.The results indicate that as l or β increases,the extrusion displace-ment of the target tunnel face and the displacement in front of the arch gradually decrease,and the stress in front of the arch gradually approaches the original state.When l＞6mor β＞0.75,the pre reinforcement ef-fect of the rock bolt on the core soil is not significant.Considering the safety and economy of the project,tak-ing l=8 m and β=0.75 is relatively reasonable and provides a certain reference basis for similar projects.
face boltcore soilsoft surrounding rockshallow tunnel
NETL
NSTL
万方数据
维普
