上界首隧道围岩稳定性分析

Analysis on Wall Rock Mass Stability of Shangjieshou Tunnel

隧道开挖过程中围岩破坏容易引发隧道坍塌事故,为了保证上界首隧道的施工安全,根据本区工程地质特征,建立了FLAC3D数值模拟模型。采用FLAC数值模拟方法对该隧道三台阶法施工全过程进行模拟分析,得到了上界首隧道的围岩变形规律。结果表明,竖向位移主要集中在拱顶和拱底处,拱顶最大位移为6.92mm,拱底最大位移为4.71mm;水平位移主要集中在隧道两肩和两腰处,最大水平位移为4.11mm。隧道开挖初期竖向位移与水平收敛速率都比较大,处于不稳定状态,而后变化速度慢慢减小,在施作仰拱支护闭合后,基本稳定下来,说明本段选用的施工方法和初期支护参数合理。

Wall rock damage may easily lead to tunnel collapse in the process of tunnel excavation.To ensure construction safety of Shangjieshou tunnel,numerical simulation models are established according to the engineering and geological features.FLAC3D is applied to simulate and analyze tunnel construction process,hence the deformation of rock.Results show that vertical displacement occurs mainly on top and bottom of the dome,with the maximum displacement of the vault 6.92 mm and the maximum displacement of arch 4.71 mm respectively;Horizontal displacement is mainly concentrated on shoulder and waist,with the maximum horizontal displacement of 4.11 mm.Initial vertical displacement and horizontal convergence rate are relatively high and in an unstable state.Then the change rate gradually decreases and becomes basically stable after the invert support is closed.It can be concluded that the construction method and the initial support parameters set are reasonable.