压力分散型无黏结预应力锚索作用机理及内锚固段长度研究

Study on anchoring mechanism of distributed pressure-type unbonded prestressed cable and its length in inner-anchoring section

本文采用有限单元法,建立了预应力锚固数值仿真模型,通过计算机模拟计算,得到了压力型锚索砂浆体内压应力分布规律和岩体与砂浆体界面上的剪应力分布规律。结果表明,砂浆体中的压应力和砂浆体与岩体界面上的剪应力在钻孔延展方向衰减很快,为了在保证工程安全的条件下降低工程造价,应根据工程实际确定内锚固段长度。本文参照国内有关规范及标准得到了不同围岩类别条件下压力分散型无黏结预应力锚索相应的临界锚固长度,对该类锚索的施工设计具有一定的参考价值。

In order to study the mechanical action of distributed pressure-type unbonded cable, a numerical simulation model of the prestressed anchor-cable has been developed. By using the model of finite element method, a series of computational experiments are performed, and press stress distribution of grouting and shear stress distribution of the interface between rock and grouting are obtained. The results indicate that these two stresses would diminish rapidly along the drilling direction. In order to ensure the safety of projects with low cost, the critical anchorage length should be determined according to practical requirement. Referring to relevant national standards and specifications, the critical lengths of inner-anchoring sections for different rock masses classifications can be worked out. The results presented here are of valuable reference for designing distributed pressure-type prestressed anchor without adherence.