针对西部地区某高原隧道遇到的国内外罕见的强挤压碎裂围岩大变形难题，通过分析隧道的变形特征和多轮方案调整后的变形控制效果，梳理解决隧道大变形问题的关键在于兼顾“防溜塌”与“控变形”的施工方案；重点研究分析隧道进口段区域构造特点、岩体特性、地应力情况以及松动圈扩展规律，并结合力学开挖模型阐明强挤压碎裂软岩隧道大变形机制。在此基础上，提出以“分部开挖防溜塌、抗锚注支护控变形”为核心的主被动联合支护理念，并形成“分部开挖、密排超前、强化钢拱架支护、施作内置式锚杆、扩大径向注浆”的强挤压碎裂软岩隧道大变形控制技术。对比优化前后的现场监测数据，发现应用大变形控制技术后，围岩变形减少超过40%，前期变形速率降低13.6 ~20.0 mm/d，钢拱架应力减小57%，有效解决了强挤压碎裂围岩引起的大变形灾害问题。
A rare large deformation of strong extrusion fractured
surrounding rock occurred to a high-altitude tunnel in the western
region of China. To effectively control such deformation, the deformation
characteristics of the tunnel and the deformation control effect of different
supporting schemes are analyzed, and the construction principle of collapse prevention
and deformation control is emphasized. Intensively, the regional structural
characteristics, rock mass characteristics, in-situ
stress, and surrounding rock loose circle expansion pattern in the entrance
section of tunnel are examined, and large deformation mechanism of tunnel in
strong extrusion fractured soft rock is analyzed based on mechanical excavation
model. Subsequently, a concept of active-passive
combined supporting with the core of "sectioned excavation to prevent collapse and arch-bolt-grouting support to control deformation" is proposed, yielding
a series of large deformation control technologies of strong extrusion
fractured soft rock tunnel. These technologies include sectioned excavation,
dense advance support, strengthened steel arch support, built-in prestressed bolt, and expanded radial grouting. The applicable
results show that the deformation is reduced by more than 40%, the early
deformation rate is reduced by 13.6－20.0 mm/d, and the
steel arch stress is reduced by 57%, effectively inhibiting the occurrence of
large deformation disasters caused by strong extrusion fractured surrounding
rock.
