锚索预应力损失与岩体蠕变耦合的理论分析

Coupling analysis between prestress loss of anchor cables and creep of rocks

基于流变力学和黏弹性力学,建立预应力锚索锚固力损失与岩体蠕变耦合的理论模型。考虑预应力锚索加固岩体时的预应力损失效应的影响,推导稳定蠕变岩体和不稳定蠕变岩体的蠕变变形方程,得出锚索预应力随时间变化的计算公式。结果表明:锚索张拉完成的一段时间内,预应力损失较快;随后预应力损失速率逐渐减小,最终趋于稳定,岩体蠕变变形也最终趋于稳定。计算结果与已有文献的试验结果对比分析,二者的曲线变化规律一致,验证了本研究模型的正确性与实用性。结合锦屏水电站锚索预应力变化与理论模型的计算结果对比,证明了本研究模型应用于工程实例的准确性,本研究模型比以往的耦合模型具有更广泛的适用范围,不仅适用于稳定蠕变岩体,也适用于非稳定蠕变岩体,对锚索锚固力的变化异常预警和边坡工程的长期安全运营有广泛的工程应用价值.

Based on rheological mechanics and viscoelastic mechanics,a theoretical model for the coupling of prestress loss of anchor and creep of rock was established.Considering the influence of prestress loss when the prestressed anchor was used to reinforce rock mass,the creep equations of stable creep rock and unstable creep rock were derived,and the formula for calculating prestress of anchor with time was obtained.The results showed that the anchor prestress loss was faster in the period of completion of anchor tension;then the rate of prestress loss was gradually reduced and finally sta-bilized,and the creep of rock also became stable.By comparing the calculated results with the experimental results in existing literature,the curves of the two were consistent,which verified the correctness of the model.The comparison between the variation of anchor cable prestress at Jinping Hydropower Station and the calculation results of the theoreti-cal model proves the accuracy of this research model applied to engineering examples.The theoretical analysis results es-tablished in this paper considering the coupling of anchor cable prestress loss and rock mass creep have a wider applica-tion range than previous coupling models,which is not only applicable to stable creep rock,but also to unstable creep rock.The warning of abnormal changes in anchor cable anchoring force and the long-term safe operation of slope engi-neering have extensive engineering application value.