宁缠隧道高地应力软岩大变形控制措施研究

Control Measures for Large Deformation of Soft Rock Under High Geo-Stress in Ningchan Tunnel

为解决高地应力软岩隧道在建设过程中支护及围岩不稳定、变形时间长、经常性设计变更的难题,通过分析国内外高地应力软岩隧道大变形控制措施成功案例,对隧道所处地应力和地质环境及其对应的工法与支护形式进行分类总结归纳,提出高地应力软岩隧道安全且经济有效的控制措施,并结合实际工程对研究成果进行分析验证。结果表明:1)宁缠隧道岩体极破碎,岩石强度低,围岩产生大变形的主要原因有极高地应力、地层岩性、节理及软化夹层、岩层产状及倾角以及人为因素的影响;2)考虑强度应力比和相对变形并结合地质构造情况对高地应力软岩隧道进行大变形分级,得出5级制分级更合理、精准;3)采取“抗让结合、柔度适度、共同承载”的变形控制理念,并通过预支护、支护、预留变形量、施工工法等措施相结合,可以有效地控制隧道大变形。

To address the problems of unstable support and surrounding rock,long deformation time,and frequent design changes in the construction process of soft rock tunnel with high geo-stress,the successful cases of large deformation control measures of soft rock tunnel with high geo-stress in China and abroad are analyzed,and the geo-stress and geological environment of the tunnel as well as the corresponding construction methods and support forms are summarized.Additionally,the safe,economical,and effective control measures for high geo-stress soft rock tunnel are proposed,and the above research results are analyzed and verified by practical engineering.The results show the following:(1)The rock mass of Ningchan tunnel is extremely broken,the rock strength is low,and the main causes for large deformation of surrounding rock are extremely high geo-stress,formation lithology,joint,and softening interlayer,rock occurrence and dip angle,and human factors.(2)The strength stress ratio and relative deformation are used to classify the large deformation of the soft rock tunnel with high geo-stress in combination with the geological structure,and the five-level classification scheme is more reasonable and accurate.(3)The deformation control concept of"antiyield combination,moderate flexibility,and common load"and the combination of pre-support,support,reserved deformation,and construction methods can effectively control the large deformation of the tunnel.