针对水工高压隧洞环锚无黏结预应力混凝土衬砌的结构特性和已建工程在施工及运行过程中暴露出来的问题,提出了将锚索钢绞线由衬砌内部移至外侧表面、锚具槽由衬砌下部的双排布置改为衬砌底部的单排布置、减小衬砌厚度和锚索钢绞线根数的结构优化方案,并对结构优化依据、可行性和结构优化前后衬砌混凝土中预应力分布状态进行了分析论证。结果表明,本文提出的结构优化方案可显著减小隧洞岩石开挖量、衬砌混凝土浇筑量和锚索无黏结钢绞线用量;在保持衬砌预压应力水平不变的基础上,环向预压应力分布更为均匀,低应力区范围显著减小;结构优化后锚具槽混凝土易于回填密实,增强了锚具保护可靠性。
Based on the structural properties of the pre-stressed tunnel lining with unbounded circular an-chored tendons in high hydraulic pressure tunnel and the problems exposed in the construction and service periods of the built projects, a structure optimization program has been put forward, including the pre-stress strands moved from the inside to the outside of the lining, replacing the double-row anchorage slots at both the left and right sides with the single-row anchorage slots located on the bottom of the lin-ing,as well as reducing the lining thickness and the quantities of pre-stress strands. The reasons and feasi-bility of the optimization were demonstrated and the stress distribution in the linings before and after the op-timization was calculated with 3D finite element method. The results show that the amounts of rock excava-tion and the lining concrete, as well as un-bonded strands were reduced significantly by the structure opti-mization. A more uniform distribution of the circumferential pre-stress and a much smaller area of low stress were reached. After the structure optimization, the concrete backfilling of the anchorage slot turned to be compacted easily,enhancing the reliability of the anchorage protection.