断层破碎带内隧道纵向受荷特征和变形分析

Analysis of Longitudinal Deformation and Stress Characteristics of Tunnel Crossing Fault Fracture Zone

为了探究断层破碎带处隧道沿纵向的变形和受力特征,首先基于筒仓理论和地层应力分布特征,考虑断层破碎带的几何特征和围岩特性,建立了断层破碎带内隧道纵向荷载简化计算模型,并利用应力传递原理进行了求解;其次将隧道简化为破碎带纵向荷载作用下的弹性地基梁,利用有限差分理论计算了破碎带纵向荷载作用下的隧道变形和受力特征。开展了相应的数值模拟和室内模型试验,结合试验数据和数值计算结果对理论模型进行了验证,并分析了埋深、破碎带宽度和倾角变化对隧道纵向变形和受力的影响。结果表明:①埋深越大,破碎带内纵向荷载越大,但纵向荷载的增长速率越小,隧道在上下盘与破碎带交界面附近的剪力和弯矩差值越小;②破碎带宽度越大,纵向荷载整体越大,隧道在上下盘与破碎带交界面附近的剪力和弯矩差值越大,最大变形位置越接近于下盘和破碎带交界面;③破碎带倾角越大,纵向荷载越接近于均布,上下盘和破碎带交界面附近变形和受力越趋于对称。

To explore the longitudinal deformation and stress characteristics of the tunnel in the fault fracture zone,on the basis of considering the geometric characteristics and surrounding rock characteristics of the fault fracture zone,combining the silo theory and stratum stress distribution characteristics,a simplified calculation model of the longitudinal load of the tunnel in the fracture zone was established and solved by stress transfer principle.Secondly,the tunnel was simplified as an elastic foundation beam under longitudinal load of fracture zone,and the deformation and stress characteristics of tunnel under the longitudinal load were calculated by finite difference theory.Finally,the corresponding numerical simulation and model test were carried out,and the theoretical model was verified by combining experimental data and numerical calculation results,the influence of the buried depth,width and inclination angle on the deformation and stress of the tunnel were analyzed.The results show that:①the greater the buried depth is,the greater the longitudinal load in the fracture zone is,but the smaller the growth rate of the longitudinal load is,the smaller the difference of shear force and bending moment near the interface between the upper and lower side walls and the fracture zone is;②the larger the width of the fracture zone is,the greater the longitudinal load is,and the greater the difference of shear force and bending moment near the interface between the upper and lower side walls and the fracture zone is,and the closer the maximum deformation position is to the interface between the lower side walls and the fracture zone;③the larger the inclination angle of fracture zone is,the closer the longitudinal load is to uniform distribution,the deformation and stress near the interface between the upper and lower side walls and fracture zone tend to be symmetrical.