大跨隧道预应力锚索承载力提升技术研究——以京张高铁八达岭长城站为例

为解决大跨度隧道常规预应力锚索承载力不足的难题，采用理论分析和现场试验对提升预应力锚索抗拔承载力的方法进行研究，提出增加锚固节和高压注浆2种提升预应力锚索抗拔承载力的方法和配套施工工艺。研究结果表明： 影响预应力锚索抗拔承载力的主要因素为锚固段注浆体与筋体抗拔承载力及注浆体与地层间的抗拔承载力，通过增加锚固节和高压注浆工艺，可显著提升预应力锚索抗拔承载力，缩减工期，降低成本，确保锚索张拉力达到设计要求，具有较高的技术经济效益。

Improvement Technology of Bearing Capacity of Prestressed Anchor Cablein Large span Tunnel: a Case Study on Badaling Great Wall Station

The bearing capacity of conventional prestressed anchor cable in large span tunnel is always insufficient. As a result, the methods for improving the bearing capacity of prestressed anchor cable are studied by theoretical analysis and field test; and the methods of increasing anchor joint and high pressure grouting are proposed. The research results show that: (1) The main factors affecting the bearing capacity of prestressed anchor cable are the pull out bearing capacity of grouting body and reinforcement body in anchoring section and that between grouting body and strata. (2) By increasing anchor joint and adopting high pressure grouting technology, the bearing capacity of prestressed anchor cable can be improved significantly, the construction period can be shortened, the construction cost can be reduced, and the cable tension can meet the design requirements with high techno economic benefit.