拉力型和压力型预应力锚索受力分析及工程应用

根据拉力型、压力型预应力锚索结构特征，本文将拉力型预应力锚索抽象为在假想滑动面处受一个集中力P，将压力型预应力锚索抽象为在锚索孔底处受一个集中力P。工程中一般假想滑动面或锚索孔底距岩土体表面较远。基于以上假定和工程条件把预应力锚索归结到空间体内一点受集中力Kelvin问题。文中引用Kelvin应力解求得了拉力型预应力锚索钢绞线侧壁、锚索孔壁剪应力τ沿轴向分布，求得了压力型预应力锚索孔壁剪应力汲正应力σ沿轴向分布。根据本文结果：建议岩体中拉力型预应力锚索设计时应以钢绞线与注浆体之间粘结强度作为设计依据。建议岩体中压力型预应力锚索在受力端增加一段钢管改进成压力局部分散型预应力锚索。建议土体中压力型预应力锚索采取孔底扩孔改进成扩大头式压力型预应力锚索。

Stress Analysis and Engineering Application of Tension and Pressure Type Prestressed Anchor Cables

According to the structural characteristics of tension-type and pressure-type prestressing anchors, this paper abstracts the tension-type prestressing anchors to be subjected to a centralized force at the imaginary sliding surface P, and the pressure-type prestressing anchors to be subjected to a centralized force at the bottom of the anchorage holes P. Generally speaking, the hypothetical sliding surface or the bottom of the anchorage holes in the project are far away from the surface of the geotechnical body. Based on the above assumptions and engineering conditions, the prestressing anchor cable is reduced to a Kelvin problem with a concentrated force at one point within the space. The Kelvin stress solution is used to find the axial distribution of shear stress t in the side wall of strand and hole wall of tension-type prestressing anchor cable, and to find the shear stress t and positive stress in the hole wall of pressure-type prestressing anchor cable. The axial distribution of pressure type prestressing anchors is found. According to the results of this paper, it is suggested that the design of tension-type prestressing anchors in rock should be based on the bond strength between the strand and the grouting body. It is suggested that the pressure-type prestressing anchors in the rock body should be improved into pressure-dispersed prestressing anchors by adding a section of steel pipe at the stressed end. It is recommended that the pressure-type prestressing anchor cable in soil body should be improved to expand the head type pressure-type prestressing anchor cable by expanding the hole at the bottom of the hole.