金甬铁路鲍村特长隧道初始应力场特征及岩爆预测分析

金甬铁路鲍村隧道长度长、局部埋深大,具有较高建设安全风险。隧址区初始地应力场是影响围岩稳定性的重要因素,是隧道工程的设计及施工的主要依据之一。根据现场实测地应力值,利用FLAC3D进行多元线性回归,反演出隧道初始地应力场,并利用FISH编程计算隧道岩爆分级,结果表明:反演结果与地应力实测结果拟合度较高,计算结果较为可靠;该区地应力场为σ_H≥σ_h≥σ_v型;中主应力值为3~11MPa,随里程增加而呈降低趋势;水平最大主应力值在10~18MPa之间,方向多与隧道轴线呈小角度相交,对隧道围岩稳定性有利;鲍村隧道岩爆级别系数低,开挖中岩爆危害小。

Characteristics of initial stress field and rockburst prediction of Baocun long tunnel on Jinhua-Ningbo railway

The Baocun tunnel of Jinhua-Ningbo railway is quite long and locally deep buried,which poses a high safety risk. The initial geostress is an important factor to affect the stability of surrounding rocks,and it is one of the main basis for the design and construction of tunnel engineering. Based on the measured in-situ stress,FLAC3 D is used to perform a multiple linear regression to invert the initial in-situ stress field of the tunnel. Then calculate the tunnel rockburst classification by using FISH programming.The results show that: the inversion results fit well with the in-situ stress measurement results which make the calculation results reliable;the geostress field in this area is the type of σ_H≥σ_h≥σ_v;the medium principal stress value is 3 ~ 11 MPa,which decreases with increasing mileage;the horizontal maximum principal stress value is between 10 MPa and 18 MPa,and its direction intersects with the tunnel axis of small angle that is good for surrounding rock stability. Baocun tunnel has a low rockburst grade coefficient,and the rockburst hazard is small during excavation.