基于子模型法的对拉式预应力闸墩锚固竖井优化研究

Research on optimization of anchor shaft for pulling prestressed pier based on sub-model

为解决对拉式锚固竖井预应力闸墩应力集中问题,对锚固竖井尺寸进行优化,以降低锚固竖井周边拉应力。以某工程对拉式锚固竖井预应力中墩为研究对象,采用三维有限元法建立预应力闸墩整体模型进行计算分析,并从整体模型中切割出锚固竖井子模型,切割边界上施加整体模型计算得到位移值,从整体模型与子模型应力计算结果可知,切割边界上应力基本相同,验证了子模型法的合理性。在此基础上,基于ANSYS优化模块零阶优化算法对锚固竖井尺寸进行优化,采用优化后的尺寸进行应力变形计算时,正常和检修2种工况下Z向最大拉应力均降低了1.1 MPa;应力集中区正常运行工况下Y向拉应力及检修工况Z向拉应力分别减小了1.0、0.7 MPa;锚固竖井顶面X、Z向拉应力区明显减小。运用子模型法和尺寸优化技术对预应力闸墩锚固竖井进行优化,可有效降低锚固竖井周边拉应力及拉应力区范围,可为工程设计提供技术支撑。

In order to solve the problem of stress concentration of prestressed pier of tensioned anchor shaft,the size of anchorage shaft is optimized to reduce the tensile stress around the anchor shaft. In this paper, the prestressed middle pier of a tensioned anchor shaft in a project is taken as the research object, and the whole model of prestressed pier is established by three-dimensional finite element method for calculation and analysis.The sub model of anchor shaft is cut out from the overall model,and the displacement value calculated by the whole model is applied on the cutting boundary.From the stress calculation results of the overall model and the sub model,the stress on the cutting boundary is basically the same,and the rationality of the sub model method is verified.On this basis,based on the zero order optimization algorithm of ANSYS optimization module,the size of anchore shaft is optimized. When the optimized size is used for stress and deformation calculation, the maximum tensile stress in Z-direction is reduced by 1.1 MPa under both normal and maintenance conditions.In the stress concentration area,the Y-direction tensile stress under normal operation condition and the Z-direction tensile stress under maintenance condition are reduced by 1.0、0.7 MPa, respectively. The X-direction and Zdirection tensile stress areas on the top surface of the anchor shaft are significantly reduced. The sub model method and size optimization technology are used to optimize the anchor shaft of prestressed pier, which can effectively reduce the surrounding tensile stress and the range of tensile stress zone, and provide technical support for engineering design.