基于非线性最小二乘的短线法节段预制线形控制研究

Study of Geometry Control for Short-Line Segmental Precasting Based on Non-Linear Least Square Method

对于采用短线法节段预制拼装施工的预应力钢筋混凝土桥,节段预制过程中较小的误差都可能导致成桥线形较大的偏差。为控制短线法节段预制过程中产生的误差,以嘉绍大桥北岸引桥(为13联70m跨预应力混凝土连续刚构桥,主梁为单箱双室斜腹板箱梁,采用短线法节段预制拼装施工)为背景,在对预制线形控制原理研究的基础上,提出基于非线性最小二乘的综合误差处理方法,并编制线形控制系统BSRI_SLCS。该方法首先计算理论预制线形,其次建立预制线形整体坐标系与节段局部坐标系,实现节段控制点坐标在不同坐标系中的变换,然后根据实测数据进行误差分析,调整匹配节段的位置。该方法在嘉绍大桥北岸引桥短线法施工中应用结果显示,成桥线形与理论线形较为接近,证明该方法对预制线形控制是可行的。

For the prestressed reinforced concrete bridge constructed by shortline segmental precasting and assembling method ,even minor errors in the segmental precast process is possible to induce greater geometry deviation of the completed bridge .To control the deviation developing during the process of shortline segmental precasting ,the north approach of Jiashao Bridge is taken as the study background .The approach is a prestressed concrete continuous rigidframe bridge with 13 units of 70 m long spans ,the main girder adopts the double cell single box girder with oblique webs ,erected by shortline segmental precasting and assembling construction .Based on the study of the theory of precasting geometry control ,the integral error handling method based on the least square method was put forward and the geometry control system BSRISLCS was programmed .In this method ,the first step is to calculate the theoretical precasting geometry ,and then to establish the global coordinate system of the precasting geometry and the local coordinates of each section ,so as to realize the conversion of coordinates of the segmental control points in different coordinate systems .The next step is to do error analysis in accordance with the measured data and adjust the locations of the matched sections .By using this method ,the geometrical shape of the completed north approach of Jiashao Bridge is close to the designed geometrical shape ,proving that this method is feasible to the control of precasting geometry .