大跨度浅埋连拱隧道施工过程中的数值模拟研究——以夏鹃路连拱隧道为例

Numerical Simulation Study on Construction Process of Large-span Shallow-buried Multi-arch Tunnel——Taking Xiajuan Road Multi-arch Tunnel as an Example

文章以夏鹃路连拱隧道为例,采用FLAC 3D有限差分软件模拟大跨度浅埋连拱隧道三台阶法开挖过程,讨论在管棚支护、管棚+锁脚锚杆支护、管棚+超前小导管注浆支护、管棚+锁脚锚杆+超前小导管注浆支护四种不同支护下隧道的拱顶下沉、周边收敛值,并得出隧道施工后的位移云图。最后,通过对比不同支护条件下隧道位移沉降值,得出隧道开挖采用管棚+锁脚锚杆+超前小导管注浆复合支护时拱顶沉降及周边收敛值最小。采用管棚+超前小导管注浆支护时隧道的位移沉降值与采用管棚+锁脚锚杆+超前小导管注浆支护的位移沉降值相近,出于经济效益考虑,也可采用管棚+超前小导管注浆支护。

Taking Xiajuan Road multi-arch tunnel as an example, the FLAC 3D finite difference software is used to simulate the three-step excavation process of large-span shallow-buried multi-arch tunnel. The vault settlement and surrounding convergence value of the tunnel under four different supports are discussed, including pipe shed support,pipe shed + feet-lock bolt support, pipe shed + advanced small pipe grouting support, pipe shed + feet-lock bolt +advanced small pipe grouting support, and the displacement nephogram after tunnel construction is obtained. Finally,by comparing the displacement and settlement values of the tunnel under different supporting conditions, it is concluded that the vault settlement and the surrounding convergence value are the smallest when the tunnel excavation adopts the composite support of pipe shed + feet-lock bolt + advanced small pipe grouting. The displacement settlement value of tunnel with pipe shed + advanced small pipe grouting support is similar to that of tunnel with pipe shed + feet-lock bolt + advanced small pipe grouting support. For economic benefit, pipe shed + advanced small pipe grouting support can also be used.