中文摘要：

为探索软岩深基坑预应力锚杆承载特性、确定基坑最危险潜在滑移面位置,借助西宁火车站大型深基坑工程,沿锚杆均匀布置钢筋计,首次对不同拉力作用下和基坑开挖过程中预应力锚杆内力进行测试,详细对比锚杆自由段与锚固段的轴力和侧摩阻力分布与传递规律。结果表明：（1）在未施加预应力和不同拉力作用过程中,锚杆轴力和侧摩阻力分布形态与传递规律与现行认识不同,较土质或岩石基坑复杂。（2）锚杆侧摩阻力中性点和最危险潜在滑移面的出现和移动是一致的,可以确定基坑最危险潜在滑移面位置和锚杆临界锚固长度。（3）锚杆支护结构设计在考虑承载力的同时,需结合当地经验,考虑其最大允许变形量;根据本文计算方法求得自由段和锚固段长度后,按＂满足锚固长度临界值要求后,自由段越长,锚固效果越好,锚固段越短越经济＂原则进行优化。（4）基坑开挖施工时,锚杆受力和变形具有时空效应;建议预应力锚杆施工后愈早施加预应力愈好;基坑上部每层的开挖深度可适当增大,而中下部则需适当降低。（5）锚杆锁定初期或对锚杆施加的预应力吨位越高,预应力损失量较大;基坑开挖过程中,锚杆预应力变化可分为初期预应力损失下降、中期波动变化、后期逐渐上升和末期稳定4个阶段。研究成果可为类似地层深基坑预应力锚杆设计施工和理论研究提供依据。

英文摘要：

In order to research the bearing behavior of prestressed anchor, determine the most dangerous slip surface potentially in deep excavation of weak rock, this research conducted the internal force test of the prestressed anchor evenly arranged along with steal under different tensile forces during excavation by making advantage of large deep excavation projects of Xining railway station first time and compared the distribution andtransfer law of rod bolt axial force in free section with fixed section in detail. The research shows that：（1） Without pulling force or during different tensile forces,the distribution and transfer law of rod bolt axial force is different from elementary knowledge which are more complicated than that in soil or rock excavation.（2） The appearance and movement of the neutral point of lateral friction force in anchor arm are in consistence with those of the most potentially dangerous slip surface. Therefore,location of most potentially dangerous slip surface and anchor arm threshold length in a deep excavation can be determined.（3） Structural bolting design needs to consider the maximum deformation as well as the bearing capacity under the local condition;lengths of the free section and anchorage calculated in accordance with this research should be optimized by the principle of ＂ meeting the threshold length of anchorage, the longer the free section, the better anchoring effect, the shorter anchoring section,the more economical＂.（4） Anchor force and deformation possess time-space effect in construction of deep excavation;its suggested that after construction,the soon prestressed anchor is prestressed the better;Each depth excavation of up layer can be appropriately increased,while the low should be appropriately reduced.（5）During the initial anchoring period or higher tonnages of prestressing imposed on the anchor,the greater loss of prestressing occurs; changes in anchor prestressing can be divided into the four stages ： First, decreasing of prestressing. Second,