隧洞破碎带围岩失稳破坏模式及控制措施研究

为了解决在隧洞开挖过程中遇到节理带、断层等软弱破碎岩带时，发生大变形、塌方等围岩失稳破坏等问题，需提前或及时做好围岩支护措施，以确保洞室围岩的稳定及施工安全。本文以长河坝水电站泄洪洞工程为研究对象，通过对现场勘测资料、隧洞开挖施工方案及工程地质条件等的综合分析，确定了软弱破碎带围岩稳定的主要影响因素，提出了隧洞破碎带围岩的典型失稳破坏模式。针对隧洞破碎带处围岩的潜在失稳问题，综合采用超前支护、开挖后及时进行喷锚+钢支撑+锚筋束联合支护，并通过有限元手段对隧洞围岩支护方案的加固效果进行了分析。有限元计算结果表明，隧洞破碎带处经及时加强支护后，围岩变形得到有效地控制，避免了洞室围岩失稳破坏现象的发生；现场监测数据及实施效果也表明及时加强支护措施对围岩稳定控制的有效性。

Failure Modes Analysis and Control Measures for Surrounding Rock Mass in Fracture Zone of Tunnel

To solve the problem that the failures of surrounding rock masses (such as large deformation and collapse) will be easily happened when encounter of developed joint fissures, fault or other weak fractured zone during the tunnel excavation process, supporting measures in advance or timely are required to ensure the stability of surrounding rock and the safety of construction. Flood discharge tunnel at the Changheba Hydropower Station was selected as a case study example, after comprehensive analyses of field investigation results, tunnel designed schemes and engineering geological conditions, the main factors effect on the failures of surrounding rock were determined, and then the typical failure modes of surrounding rock were proposed. For the potential instability problems in fracture zone of tunnel, advance supporting measures and spray anchoring, steel supporting, anchor wire bundle combined supporting measures were applied, and reinforcement effect of supporting measures for rock mass was analyzed. The results showed that deformation of surrounding rock was controlled effectively after being supporting timely, which prevented surrounding rock from failure, moreover, the field monitoring data and application effects proved the effectiveness of reinforcing supporting measures timely controlling the stability of surrounding rock mass.