断层影响下隧道受荷特征及围岩变形研究

Research on the Load Characteristics of Tunnels under the Influence of Faults and the Deformation of Surrounding Rocks

为研究隧道穿越断层破碎带围岩受荷特征及围岩变形敏感性,依托五道岭隧道工程,采用钢表面应变计监测隧道施工过程中钢拱架应力变化,并建立隧道穿越F8断层的三维有限元模型,研究采用台阶法施工时隧道围岩变形规律及应力演化特征,建立正交试验分析断层破碎带形态参数对隧道围岩竖向位移的敏感性。结果表明:断层破碎带使隧道初期支护右拱腰处钢拱架内环应力由压应力转变为拉应力,隧道初期支护钢拱架受到偏压应力作用;隧道围岩最大拱顶沉降位于断层破碎带中部,最大仰拱隆起位于断层破碎带后部,分别相比于隧道与断层破碎带交界处的围岩位移值增大了10.5%和40.5%;隧道围岩变形受断层倾角影响最显著。

In order to study the loading characteristics and deformation sensitivity of the surrounding rock in the tunnel crossing fault fracture zone,the steel surface strain gauge is used to monitor the stress change of steel arch during tunnel construction.A three-dimensional finite element model of tunnel crossing F7 fault is established to study the deformation law and stress evolution characteristics of surrounding rock of tunnel under step method construction.Orthogonal test is established to analyze the sensitivity of morphological parameters of fault fracture zone to vertical displacement of tunnel surrounding rock.The results show that the fracture zone changes the stress of the inner ring of the steel arch at the right arch waist of the initial support of the tunnel from compressive stress to tensile stress.At the initial stage of the tunnel,the supporting steel arch is subjected to bias stress.The maximum vault settlement of tunnel surrounding rock is located in the middle of fault fracture zone.The maximum invert uplift is located behind the fault fracture zone.Compared with the boundary of tunnel and fault fracture zone,the displacement of surrounding rock increases by 10.5%and 40.5%respectively.The deformation of tunnel surrounding rock is most obviously affected by the dip angle of fault.