大跨径尾水岔洞开挖与衬砌稳定分析

 针对目前国内外水利工程中大跨径地下尾水岔洞开挖与衬砌稳定分析现状，对其存在的主要问题进行讨论。总结大跨径尾水岔洞开挖与衬砌稳定的分析方法，包括数值模型建立原则、分析内容、流程、评价指标等。应用此分析方法，对溪洛渡水电站尾水岔洞开挖与衬砌稳定开展研究，包括大跨径尾水岔洞开挖过程中变形、应力及屈服区分布特点，以及不同应力释放荷载条件下的喷锚支护效果；针对运行和检修工况，分析岔洞围岩、衬砌结构的变形及应力分布情况，变形计算结果与监测结果一致。通过实际工程分析与应用，表明所建议的大跨径地下尾水岔洞开挖与衬砌稳定分析方法可用于指导同类岩土结构工程设计。

STABILITY ANALYSIS OF EXCAVATION AND LINING STRUCTURE OF LARGE-SPAN TAILRACE BIFURCATION TUNNEL

The current research situation and commonly used method of stability for excavation and lining of large-span tailrace bifurcation tunnel at home and aboard are reviewed. Based on summary studies，an evaluation method to analyze the stability of excavation and lining structure is proposed. It involves the basic principles of numerical method，analytical contents，flow charts and evaluation index. By employing this evaluation method，the tailrace bifurcation tunnel of Xiluodu hydropower station is analyzed，including the distribution characters of deformation，stress and yield zone in the surrounding excavated rock mass and the reinforcing effect under different stress releasing conditions. The deformation and stress state in surrounding rock mass and lining structure also are investigated under operation and maintenance loading conditions. The numerical results and monitoring results are consistent. Based on the numerical results of practical projects，it shows that the proposed evaluation method related to tailrace bifurcation tunnels can be applied to the design and construction of the similar projects.