高地应力与地震联合作用下软弱围岩隧道动力响应研究

Study on Dynamic Response of Soft Rock Tunnel Under Combined Action of High Geostress and Earthquake

针对高地应力、软弱围岩、高地震烈度等多种因素并存环境的隧道在高地应力与地震联合作用下隧道支护结构的安全性问题,依托某铁路隧道,根据岩体强度应力比与相对变形值两个指标,确定了三种软弱围岩变形等级的分级标准;结合三维数值仿真分析,研究不同变形等级的软弱围岩条件下围岩与隧道支护结构在地震波作用下的动力响应规律。结果表明:围岩变形等级越大,隧道位移差越大;围岩加速度响应主要受入射地震波与围岩自身性质影响,与软弱围岩变形等级无关;不同变形等级下隧道横断面支护结构的弯矩、轴力极值规律大致相同,随着软弱围岩变形等级提高,隧道二次衬砌内力逐渐增大,安全系数逐渐降低,且在拱顶与左右拱脚处安全系数较小。在软弱围岩大变形段与隧道支护结构拱顶与左右拱脚处应注重抗震设防。

Aiming at the safety problem of tunnel supporting structure under the combined action of high geostress and earthquake in the environment of high geostress,soft surrounding rock,high earthquake intensity and other factors,based on a railway tunnel,the classification standards of three kinds of soft surrounding rock deformation grades were determined according to two indexes of rock strength stress ratio and relative deformation value.Combined with three-dimensional numerical simulation analysis,the dynamic response laws of surrounding rock and tunnel supporting structure under the action of seismic wave were studied under the condition of soft surrounding rock with different deformation levels.The results show that the greater the deformation grade of surrounding rock is,the greater the displacement difference of tunnel will be.The acceleration response of surrounding rock is mainly affected by the incident seismic wave and the properties of surrounding rock,and has nothing to do with the deformation grade of soft surrounding rock.Under different deformation levels,the extreme values of bending moment and axial force of tunnel cross-section support structure are almost the same.With the improvement of soft surrounding rock deformation level,the internal force of tunnel secondary lining increases gradually,the safety factor decreases gradually,and the safety factor at the vault and left and right arch feet is smaller.In the large deformation section of soft surrounding rock and the vault and left and right arch feet of tunnel supporting structure,the seismic fortification should be paid attention to.