深基坑预应力锚杆锚固段应力分布规律与应用

Application of stress distribution to bonded section in priestesses anchor for deep foundation pit

基于凯尔文问题的位移解,推导了用于深基坑支护中的预应力锚杆锚固段剪应力与轴力的分布规律。对岩体与土体两种不同介质条件下预应力锚杆的受力分析表明,不同岩土体介质条件下,预应力锚杆破坏方式不同,要以最薄弱环节作为锚杆设计控制标准;锚杆剪应力沿锚固段呈对数螺旋曲线型分布,最大剪应力往往发生靠近锚固段初始位置处;锚杆轴力沿锚固段逐渐衰减,单纯通过提高锚固段长度来增加锚杆的极限拉拔力有一定的限度。通过对一工程实例的理论与试验对比分析,其弹性范围内的理论解与试验数据基本相吻合,从而为预应力锚杆的设计提供了理论依据。

Based on the Kelvin displacement solution, the distribution of shearing stress and axial force along the anchored length to prestressed anchor in deep foundation pit is obtained. The deformation failure mechanical style of prestressed anchor to rock medium and earth medium is different. As the design controls specifications, the weakest link to presstressed anchor is very important in different medium. The distribution expression of shearing stress is a logarithmic spiral curve along anchored length to prestressed anchor, and the maximum shearing stress is located at the initial position of anchorage section. The axial force is attenuated along anchor bore depth, and the improvement of the ultimate resistance capacity to prestressed anchor through increasing the anchorage section length is very limited once the anchorage length exceeds a certain level. An instance is analyzed and the theoretical solution fits well with the test results in elastic range. The obtained conclusions can offer references to prestressed anchor engineering design in deep foundation pit.