断层破碎带区域贯通施工的富水隧道力学特性分析

Analysis of Mechanical Characteristics of Through Construction Water-rich Tunnel in Fault Fracture Zone

以福建莆炎高速公路文笔山1#隧道工程为背景依托,基于渗流场—应力场耦合基本理论,采用数值模拟方法,建立有限元三维数值模型,研究破碎带贯通的富水深埋隧道力学特性,并通过参数分析量化不同水头高度的富水环境工况下的应力、塑性区贯通范围、拱顶沉降、孔隙压力、掌子面挤出变形等关键因素的影响。研究结果表明:隧道开挖过程中围岩应力集中在拱腰处,且在拱腰围岩处的最大主应力、拱顶沉降与拱底隆起分别随着水头高度增加呈减小和增大趋势;塑性区随着水头高度的增加,贯通距离增大,掌子面挤出变形增大,且开挖进尺的减小,掌子面的稳定性越高。隧道在开挖过程中孔隙压力向隧洞周围集中,且隧道开挖面在初期支护及时封闭后孔隙水压力趋于稳定;地下水不仅会增大贯通区的突涌水量,还会显著增大隧道贯通区的挤出变形,提高失稳风险,隧道应尽量避免在富水区域贯通。

Based on the basic theory of seepage field-stress field coupling,a three-dimensional finite element numerical model was established by numerical simulation method to study mechanical characteristics of through construction water-rich tunnel in fault fracture zone,with the background of Wenbishan 1#tunnel project on Puyan Expressway in Fujian Province.Through parameter analysis,the influence of key factors such as stress,plastic zone penetration range,vault settlement,pore pressure and extrusion deformation of palm surface under water-rich environment conditions with different water head heights is quantified.The results show that the stress of surrounding rock is concentrated at the arch waist during tunnel excavation.The maximum principal stress at the surrounding rock of the arch,arch roof settlement and arch bottom uplift decrease and increase respectively with the increase of water head height.With the increase of water head height in the plastic zone,the penetration distance increases,the extrusion deformation of the palm surface increases,and the excavation footage decreases,the stability of the palm surface is higher.During the excavation of the tunnel,the pore pressure concentrates around the tunnel,and the pore water pressure tends to be stable after the tunnel excavation surface is closed in time with the initial support;groundwater will not only increase the sudden water inflow in the penetration area,but also significantly increase the extrusion deformation in the tunnel penetration area and increase the risk of instability.The tunnel should try to avoid penetration in the water-rich area.