不同加载状态曲线锚索沿程预应力损失试验研究

Experimental Study on the Variation Law of Prestress Loss Along the Curved Anchor Under Different Loading States

曲线锚索沿程预应力损失是影响衬砌结构应力分布的关键因素,获取摩擦系数和偏差系数尤其重要。开展不同加载状态曲线锚索沿程预应力损失研究,建立了模型试验平台,进行了不分级加载、分级加载和分级循环加载测试,分析了锚固端和张拉端受力特征、预应力损失变化规律、摩擦系数和偏差系数取值,并结合实际工程计算了曲线锚索任意点受力值。结果表明:曲线锚索沿程损失摩擦系数和偏差系数不仅与材料自身属性有关,还受到力学加载状态影响;与不分级相比,分级加载曲线锚索平均预应力损失由8.47%降低至3.63%,且各级荷载必须给予足够停滞时间,以保持预应力传递;分级循环加载曲线锚索预应力沿程损失大幅降低,而加载时长却较久,不适宜作为常规加载方式,宜作为极个别曲线锚索预应力值不能达标时的应急处置方案。

The prestress loss along the curve anchor cable is the key factor affecting the stress distribution of lining structure,and it is particularly important to obtain the friction coefficient and deviation coefficient.The prestress loss along the curve anchor cable under different loading states is analyzed,the model test platform is established,the non-graded,graded and graded cyclic loading tests are carried out,the stress characteristics of the anchor end and tensioning end,the variation law of prestress loss,the values of friction coefficient and deviation coefficient are analyzed,and the stress value at any point of the curve anchor cable is calculated in combination with the actual project.The results show that the friction coefficient and deviation coefficient along the curve anchor cable are not only related to the properties of the material itself,but also affected by the mechanical loading state.Compared with non-graded loading,the average prestress loss of graded loading curve anchor cable is reduced from 8.47%to 3.63%,and sufficient dead time must be given for all levels of load to maintain prestress transmission.The loss of prestress along the way of graded cyclic loading curve anchor cable is greatly reduced,but the loading time is long,so it is not suitable to be used as a conventional loading method but an emergency disposal scheme when the prestress value of very few curves anchor cables cannot meet the standard.