敞开式TBM穿越深埋中强蚀变岩区钢结构承载性能研究

Study of bearing capacity of steel structure at the deeply buried medium-strong altered rocks area where open-type TBM passing through

深埋中强蚀变岩因蚀变程度均一性差,造成洞周围岩强度不均,局部承载力极低,蚀变岩岩性受地下水作用明显,富水蚀变岩区易产生塌方、拱架大变形等问题,对TBM的顺利通过造成巨大威胁。根据某深埋TBM长隧洞工程穿越中强蚀变岩区的工程实际,结合敞开式TBM出露盾尾后围岩变形及破坏特征,提出了能有效控制掉渣量的“钢板+钢拱架”联合钢结构支护结构系统,并采用有限元方法对钢结构支护系统的承载力进行了详细分析。工程采用钢结构系统后,拱架应力稳定,掉渣量明显减少,保证了敞开式TBM成功高效穿越中强蚀变岩区,为类似工程提供了借鉴。

Homogeneity of degree of alteration of deeply buried medium-strong altered rocks area is poor.It results in the uneven strength of rocks surrounding to the cavern and the bearing capacity is extremely low.The altered rocks are affected by the groundwater obviously and it will be easy to collapse and to result in the large deformation of the arch,and all of these pose a great threat to the TBM passing.It is combined the practical engineering experience of TBM passing through the medium-strong altered rocks area in the deeply buried long tunnel project and the surrounding rock deformation and failure characteristics after the open-type TBM in this paper,and provides the‘steel plate+steel arch centering’combined steel structure support system that can effectively control slag quantity.Besides this,it also analyzes bearing capacity of combined steel structure support system by FEM method.In the practical application of the combined steel structure support system,the stress of the arch is stable from the monitoring data and the slag quantity reduces obviously.It keeps the open-type TBM passing through the strong altered rocks area successfully and it provides the useful experience to other similar projects.