高地应力软岩隧道松弛效应研究

Stress Relaxation Effect in a Soft Rock Tunnel with High Geo-Stress

高地应力软岩隧道的长期稳定性评价是个技术与理论难题,隧道工程衬砌施工后,一方面要承担由于岩体本身强度较低而产生的蠕变变形,另一方面需要承担围岩的自承能力随时间不断降低产生的松弛荷载。高地应力软岩隧道通过选择合理的施工工法和支护参数,减小围岩的变形和松动范围,降低作用在支护结构上的荷载,是当前软岩隧道设计施工的重要发展方向。以某高速公路隧道软岩隧道为例,通过现场地应力测试与数值仿真,研究其松弛机理,为高地应力软岩隧道的设计与施工方案的选择提供有益的探索。

The construction of the deeply embedded tunnel in the soft rock with high in situ geo-stress and its long-term stability evaluation are still the worldwide technical and theoretical challenges.This type of tunnel construction hazard prevention has become the focus of the excavation construction engineering.After the tunnel lining installation,on the one hand,it would be able to carry the creep deformation caused by the low strength of the surrounding rock mass,on the other hand,it also could take the relaxation load caused by the continuous reduction of the self-supporting capacity of the surrounding rock mass with time.Therefore,it is a key developing direction for the design and construction of the tunnel in the soft rock mass with high in-situ geo-stress to reduce the deformation and looseness range of the surrounding rock mass and reduce the load acting on the lining system as much as possible by selecting the reasonable construction methods and support parameters.In this paper,a highway tunnel in the soft rock mass is presented as an example to study its relaxation mechanism through the in-situ geo-stress tests and numerical simulation,which provides a useful exploration for the design and construction selection of tunnels in the soft rock with high geo-stress.