考虑锚索松弛特性的预应力损失计算模型研究

基于等效应变原理,考虑耦合效应与锚索松弛特性,将锚索自身与周围介质代以松弛组合元件、广义开尔文组合元件,提出了一种新的预应力蠕变损失计算模型,并推导了其特征方程(本构方程、蠕变方程、松弛方程),阐述了锚固力损失与围岩变形之间的计算关系;在材料参数已知的情况下,对比应力应变新模型计算结果与试验测试数据可知:(1)随着锚索张拉控制应力的不断提高,锚索应变测试初值和终值不断增大,呈正相关;(2)应变测试曲线基本遵循"幂函数"趋势,表现为初期加速增长,后趋于平稳增长,最后保持基本水平;(3)蠕变计算新模型较原耦合模型更贴近相似试验测试结果,且应力与应变变化规律相符;研究成果为锚索预应力工程的设计、施工提供了理论支撑和借鉴参考。

A Coupled Model Research of Anchor Prestress Loss Considering the Relaxation Characteristics of Anchor

Basing on the principle of equivalent strain,taking into account the coupling effect and relaxation properties,anchor and the surrounding rock were respectively simulated by relaxation model and the general Kelvin,so a new creep coupling model,which could describe the interaction relationship between the prestressed anchor and rock creep deformation,was proposed.And the corresponding constitutive equations,creep equation,relaxation equation were deduced,which could theoretically explain the computing relationship of the prestressed loss and rock creep deformation.On the base of existing similar model test,Comparison of anchor strain test data and the calculation results shows that:with the continuous increasing of tension stress,the initial and final measurement values of anchor were rising.Strain measurement curve basically followed the "exponential" form.With time lasting after locking,the performance showed a initial accelerated growth,then a stabilized growth,a final basic level.New creep calculation model than the original coupled model,was closer to the results of similar test.And the variation of stress was consistent with the strain variation.Research provides a theoretical basis and technical support for the future design and construction of long-term forecasting prestressed anchors.