兰州黄河高阶地复杂地质大断面隧道监控量测

兰州地区黄河阶地是国内最为典型的河流阶地,地质条件复杂。本文结合兰新第二双线兰州枢纽引入工程孔家营隧道施工,选择典型断面(阶地黄土地层、阶地黄土圆砾土地层、阶地圆砾土软岩地层、阶地黄土圆砾土软岩地层)对该隧道施工进行全面、系统监控量测,对比分析了各种地质条件下的大断面隧道的应力变形特征。结果表明,不同地层组合隧道围岩稳定性具有较大的差别,尤其是隧道拱顶存在圆砾土时其稳定性最差;阶地隧道存在较明显的偏压现象,二衬可以很好地控制偏压对隧道稳定性的影响。

Monitoring and Measurement for Large Cross-Section Tunnel in Complicated Geological Condition of Yellow River High Terrace in Lanzhou

Yellow River terrace in Lan-Zhou area is the most typical river terrace for its complicated geological condition. Combined with the tunnel construction of introduction engineering of Lanxin second double hub into Kongjiaying, compre- hensive and systematic monitoring is carried out by selecting typical cross-section （ terrace loess formation, terrace loess and circle gravel soil formation, terrace circle gravel soil and soft rock formation, terrace loess circle gravel soil and soft rock formation） to analyze and compare the stress deformation characteristics of large cross-section tunnel under various geolog- ical conditions. The results show that the stability of surrounding rock differs greatly in different strata combination of tunnel, the tunnel stability, in particular, is wont when there is round gravel soil in vault; a more obvious eccentric compression is found in terraces tunnel, and the impact of eccentric compression on the stability of the tunnel can be well controlled by the secondary lining.