穿黄隧洞内衬预应力混凝土强度有限元计算分析

为验证穿黄隧洞内衬预应力混凝土强度,根据穿黄隧洞双层复合衬砌结构的特点与作用模式,在考虑钢绞线与孔道摩擦、锚具变形及钢筋内缩等引起预应力损失的前提下,采用三维非线性有限元模型对内衬预应力混凝土强度进行了分析与验证。通过计算得出有效预应力在钢绞线上的分布情况,以及分别在张拉工况与设计水头工况下内衬混凝土的内外表面环向应力和平均环向应力的分布规律。计算结果表明:张拉过程中的预应力损失较为严重,需要在施工过程中严格控制张拉应力以及其他引起预应力损失的影响因素,以保证张拉后有效预应力满足强度要求;穿黄隧洞内衬混凝土在两种工况下均实现全截面受压,应力分布满足设计要求,可保证穿黄隧洞的长期有效运行;模拟计算结果的应力参数值与1∶1仿真模型试验值吻合良好,变化规律与关键参数均基本一致。

Finite Element Calculation and Analysis of the Strength of Prestressed Concrete Lining of Yellow-River-Crossing Tunnel

The strength of prestressed concrete lining of Yellow-River-crossing tunnel was analyzed and verified by using 3-D non-linear finite element model. According to the features and action mode of the double composite lining structure, the prestress loss caused by the friction between steel strand and duct, the anchorage device deformation and the inward shrink of steel was taken into account. The distribution of effective prestress in prestressed steel strand was obtained. The distribution of hoop stress in the inner and exterior surface of the lining, as well as the average hoop stress respectively under the stretched steel strand condition and the design waterhead condition was also acquired. The calculation results indicate that the loss of prestress is severe when the steel strands are stretched. The tension stress and other factors affecting the loss of prestress should be controlled strictly so that the effective prestress could meet the strength requirement. Under the above two conditions, the whole section of the concrete lining is totally pressed and its stress distribution is also feasible enough to assure the tunnel’s long-term running. The basic variation and key parameters such as the stress parameters of the numerical calculation results are consistent with those of the full-scaled simulation model test.