不同围岩和埋深条件下隧道围岩位移和应力变化规律分析

采用FLAC3D计算了II～V级围岩在30 m、100 m、200 m、300 m、400 m和500 m埋深下的拱顶沉降和塑性压力,II和III级围岩拱顶沉降(包括开挖面拱顶沉降和最终拱顶沉降)随埋深呈线性增大,IV和V级围岩拱顶沉降随埋深呈非线性快速增大;开挖面拱顶沉降收敛比(开挖面拱顶沉降占最终拱顶沉降的百分比)随埋深增大而减小,随围岩等级降低而减小,表明深埋弱围岩中隧道要趁早支护。围岩塑性压力随埋深增加而增加、随围岩等级降低而增加,表明深埋弱围岩隧道支护结构受到的围岩压力大。最后对围岩应力集中及其影响因素进行了分析。

Numerical Analysis of Stress and Strain Around Rock Tunnel with Different Surrounding Rock Condition and Buried Depth

The crown settlement and plastic pressure of the tunnel surrounding rock graded by Ⅱ～Ⅴ and buried at the depth of 30 m,100 m,200 m,300 m,400 m and 500 m were analyzed using FLAC3D program.The crown settlement of the Ⅱ and Ⅲ graded rock linearly increased with the buried depth,and that of Ⅳ and Ⅴ graded rock increased with depth in exponent function.The numerical analysis results of the crown settlement implied that the composite support structure of the tunnel deeply buried by weak rock should be constructed in early stage.The plastic pressure of the surrounding rock increased with buried depth,and decreased with the rock grade,which meant the composite support structure of the tunnel deeply buried by weak rock would support high pressure.The stress concentration and its affecting factors were analyzed at last.