不同施工工法对既有隧道影响的数值模拟研究

文章通过数值分析手段,对拟建隧道采用不同的施工方法所引起交叉既有隧道的受力、变形变化状况进行研究。全断面法与上下台阶法对既有隧道的围岩应力及变形影响是一致的,两者均引起拱顶及边墙的围岩应力降低,拱底围岩应力的增高,既有隧道特征点均将产生下沉。全断面法开挖引起既有隧道的位移量要稍大于上下台阶法,同时2种开挖方法对既有隧道二衬的受力影响几乎相当,二衬经历对称—非对称—对称3个变化过程,随着开挖深入,其应力逐渐增大,但远小于容许应力值,处于安全状态。并据此提出相应的建议。

Study on influence of two different construction methods on an existing tunnel by numerical simulation

Numerical simulation is made to analyze the change of an existing tunnel in the stress and displacement as the tunnels that cross it are to be constructed with two different construction methods.The influence of the two methods on the existing tunnel is the same.The stress in the arch and side-wall is reduced,but that in the arch tunnel bottom is augmented,and sinking occurs in the characteristic points of the surrounding rock.The displacement of the existing tunnel influenced by the full face excavation method is slightly bigger than that by the bench cut method.The both methods bring similar effects on the stress in the secondary lining,and the stress undergoes a symmetric-asymmetric-symmetric process,and it increases as the excavation is made forward.But the stress is less than the allowable value,so the secondary lining is in a safe condition.Some suggestions are presented.