软岩大变形隧道锚喷支护的力学效应及失效原因分析

目前隧道锚喷支护设计仍采用以经验为主的工程类比法,由此造成支护参数与围岩地质条件不能完全匹配,在软弱岩体隧道中常引发围岩失稳大变形现象。以油坊坪隧道为例,首先对现场围岩失稳及破坏特点进行了分析,运用剪切滑移理论对锚喷支护系统的力学效应进行计算分析。计算结果表明,设计的锚喷支护参数具有足够的安全度,现场围岩失稳主要是由于施工扰动,促使本来较为软弱破碎围岩进一步恶化,造成锚喷支护体系无法达到设计的支护抗力,加上远超过计算值的实际形变围岩压力最终形成剪切破坏;据此提出施工方面的建议,为类似条件下隧道施工避灾减灾提供参考。

Analysis of Bolt and Shotcrete Support in Soft Large-deformation Tunnel

At present the tunnel bolt-shotcrete support design is still using the engineering analogy method based on the practice experience, and the supporting parameters and surrounding rock geological conditions cannot be completely matched which caused the supporting damage and large deformation in soft and weak tunnels. Taking You Fang-ping Tunnel as an example, analyzed the destruction characteristics and development process of bolting and shotcrete lining through the field investigation. Using Shear-slippage theory, the stability of shotcrete support has been calculated, the result showed that the designed bolt-shotcrete support parameters had enough secure reserve. The construction disturbance caused the weak rock mass into further deterioration which was resulting in shotcrete support system can not meet the design support resistance. The actual deformation larger than design value caused great rock pressure and the formation of shear failure ultimately. It can propose the suggestion for tunnel construction, and provide a reference for disaster prevention and mitigation under similar conditions.