输水隧洞预应力混凝土衬砌应力正交敏感性分析

Orthogonal sensitivity analysis of prestressed concrete lining stress of water conveyance tunnel

为了分析输水隧洞预应力混凝土衬砌结构应力对相关因素的敏感性,以穿黄隧洞工程为例,选取张拉控制应力σcon、预应力钢筋与孔道壁的摩擦系数μ、钢绞线孔道局部偏差摩擦系数k以及锚具变形和钢筋内缩值a等4个因素作为敏感性参数,通过正交试验设计法确定计算方案,采用三维有限元方法计算了各因素不同取值时管壁混凝土的应力状态。利用极差分析方法分析了管壁混凝土环向应力和轴向应力对上述4个因素的敏感性。结果表明,在钢绞线张拉完成、充水达到设计水压的两种工况下,管壁混凝土环向应力和轴向应力对这4个因素的敏感性由高到低依次为:μ、σcon、a、k,特别是μ和σcon对管壁混凝土环向应力有显著影响,在数值计算中需要评估或者通过试验验证这2个因素取值的准确性,以保证参数取值反映实际情况以及数值计算结果的可靠性。

To evaluate the sensitivity of the prestressed concrete lining stress to the related factors, the stretching controlling stress ？con, friction coefficient between prestressed steel and channel wall, local deviation friction coefficient of strand channel k, and anchorage deformation and steel shrinking value a were selected as the sensitivity factors in this paper based on the background of Yellow River crossing tunnel project. The orthogonal experiment design method was used to determine the calculation scheme, and the stress state of wall concrete was calculated using the three-dimensional finite element method with different values assigning to the factors. The sensitivities of hoop stress and axial stress of the wall concrete to the four above factors were analyzed with the range analysis method. The orthogonal experiment results showed that the magnitude of sensitivities of hoop stress and axial stress of the wall concrete to the four factors under the conditions of completed strand tension and water filling reaching design water pressure is in the order of μ, σcon, a, and k, and especially μ and σcon have a significant impact on the hoop stress. Therefore, the value accuracy of the above two factors must be evaluated or validated by the experiments to ensure that the parameter values can reflect the real situation and the results of numerical calculation are reliable .