考虑高边坡强卸荷的锚索锚固力耦合变化模型

A model of anchorage force loss of anchor cable during high slope strong unloading

在岩质高边坡锚固工程建设中,锚索的锚固力能否长期维持决定着边坡锚固工程的成败。因此,研究锚索锚固力的时效变化规律至关重要。以不同地区的高边坡锚固工程为例,讨论了高边坡强卸荷作用与工程初期锚固力快速损失的对应关系,并分析了在强卸荷作用影响下的高边坡锚索前期锚固力损失差异机制。通过案例总结出锚索锚固力变化模型的建立需要考虑高边坡强卸荷作用对锚固力损失的影响,基于锚固力损失与高边坡岩体时效变形的耦合效应,将引入转化时间K的西原流变模型与模拟锚索体并联,建立了锚索锚固力的耦合变化模型,推导出锚索锚固力长期变化的理论方程。结合锦屏水电站左岸高边坡LE1915排水洞与L2J连接洞K0+126 m下游附近的锚固力实测数据与已有理论模型对比,证明了新模型应用于开挖强卸荷的高边坡工程中的准确性,比以往的耦合模型具有更广泛的适用范围,不仅为高边坡锚固工程锚索锚固力的控制与补偿时间提供了理论依据和技术手段,而且对锚索锚固力的变化异常预警和高边坡工程的长期安全运营有重要意义。

During construction of anchorages for a high rock slope, whether the anchorage force can be maintained is the key to the slope anchorage engineering, and thus it is essential to understand time-dependent variation mechanisms of the anchoring force. Firstly, we discussed the high slope anchorage engineering projects which had significant sustained loss of anchoring prestress, analyzed the occurrence mechanism of such rapid variation of the anchoring prestress, and found that it is inevitable to consider the effect of high slope strong unloading on the initial anchoring prestress loss process during the calculation. Then, based on an improved visco-elastoplastic model, a new model was established by introducing conversion time K and a prestressed anchor cable in parallel. Finally, through the anchored cable’s prestress monitoring data of LE1915 drainage hole and L2 J connect hole 0 ＋ 126 m on the left bank of Jinping I hydropower station, the newly developed model is verified to be suitable to be applied in high slope anchoring engineering, and also confirm its accuracy and broad application by comparing with the original model. Not only the newly developed model provides theoretical guidance and technical means for the control and compensation of anchor cable’s anchorage force, but also has an important significance to the long-term safe operation and early warning of high slope anchoring project.