Prediction of Rockburst Tendency and Study of Influencing Factors in Extra-Long Deep-Buried Tunnels
Rockburst tendency prediction is a challenge in the construction of deep-buried hard rock tunnels.Previous studies have mainly relied on on-site monitoring data from tunnel construction,but these predictions are limited by their timeliness and scope.Based on the field-measured data of geo-stress from an extra-long deep-buried tunnel engineering area in Southwest China,a three-dimensional numerical inversion analysis of the regional stress field was conducted to obtain the axial stress charac-teristics of the tunnel.This enabled the prediction of rockburst tendency levels during tunnel construc-tion.Numerical simulation methods were used to compare and analyze the influencing factors of rock-burst.The results can serve as a reference for similar extra-long deep-buried tunnel projects.The re-search results showed that:(1)The overall trend of the three-direction principal stress near the mea-surement point was σH>σv>σh,with the maximum horizontal principal stress σH ranging from 10.96~17.07 MPa,oriented at N9°W~N7°E.(2)The maximum horizontal principal stress σH in the tun-nel was 23.88 MPa,while the minimum horizontal principal stress σh was relatively constant.The ver-tical principal stress σv reached 46.70 MPa,and its variation was positively correlated with the tun-nel′s burial depth.The tunnel met the basic conditions for rockburst occurrence,with moderate to strong rockburst risk during construction.(3)When the lateral pressure coefficient was 0.8,the rock-burst tendency was higher at the wall corners,while other locations exhibited similar tendencies.The greater the burial depth,the higher the rockburst tendency,and the impact of burial depth on rock-burst tendency was generally consistent across different locations.When the elastic modulus of the sur-rounding rock was 40 GPa,the rockburst tendency was the largest.When the internal friction angle of the surrounding rock exceeded 40°,the rockburst tendency across the tunnel section became stable.
deep-buried tunnelrockburst predictiongeo-stress field inversioninfluencing factors