新建隧道下穿既有构筑物在偏压状态下的施工方法探析

分析3种不同工况下新隧道开挖对既有隧道的影响,得出3种不同工况对既有隧道围岩的位移与应力所产生的影响一致,都会使既有结构的特征点下沉且应力下降,当围岩应力与位移量比较小时,既有隧道处于一种稳定状态.根据分析结果决定一般地段的开挖方式为全断面法,且在交叉口位置前后不同洞泾范围内实施台阶法开挖,最后结合影响范围明确具体监控方案,以此指导设计以及施工.

On Construction Methods of Penetrating the Existing Downward Structure in the Newly-built Tunnel under the Flat Pressure Condition

This article attempts to analyze the effects of digging new tunnel on the existing tunnel under three different constructing conditions , and comes up with the conclusion that the effects of replacing the enclosed rocks of the existing tunnel are the same as those of the corresponding strain under the three different construction conditions.Furthermore, the effects will make the feature points of the existing structure sink and the strain lower down , but if the strain of the enclosed rocks and the replacement quantity are relatively smaller , the tunnel will remain stable.Therefore, it is suggested that the design and the construction should be under the guidance of the analysis results of the construction sites：full section method should be adopted in the normal construction sites and bench cut method should be conducted in the upper and lower intersection of tunnels of different diameters , and finally the specific monitor measures will be worked out based on the affecting range of the construction .