改进灰色模型的隧道锚极限承载力研究

Study on Ultimate Bearing Capacity of Tunnel-type Anchorage by Improved Grey Model

以某悬索桥隧道锚为研究对象,开展1∶12现场隧道锚缩尺模型拉拔试验,通过超载试验得到锚体及其周围岩体的变形量,分析隧道锚围岩的极限承载力变化,建立一种基于对数变换的改进灰色预测模型,进而提出了一种预测隧道锚围岩极限承载力的方法。结果表明:对数变换有效提高了灰色模型的预测精度,利用遗传算法得到对数控制方程的关键参数合理可用,通过灰色预测模型计算得出锚体围岩的极限承载力为7.28倍的设计荷载,其与通过模型超载试验得到的7.6倍设计荷载基本一致,且满足锚体安全系数的设计要求;研究成果可供悬索桥的建设提供技术支撑。

The tunnel-type anchorage for a suspension bridge was taken as the object of study in this paper,the scale model test of 1 ∶ 12 tunnel-type anchorage was carried out,and the deformation of anchorage body and surrounding rock mass was obtained by overloading test. The change of ultimate bearing capacity of surrounding rock of tunnel-type anchorage was analyzed,then an improved grey prediction model based on logarithmic transformation was established,finally,a method to predict the ultimate bearing capacity of tunnel surrounding rock was put forward.The results show that the logarithmic transformation improves effectively the prediction accuracy of the grey model,the key parameters of the logarithmic governing equation were reasonably obtained by using genetic algorithm,the ultimate bearing capacity of the anchorage surrounding rock was calculated to be 7.28 times the design load with the grey prediction model,which is consistent with the overload test result,7.6 times design load,this meets the design requirements of the safety coefficient of anchorage; the research results can be used to provide technical support for the construction of suspension bridge.