变曲率竖曲线梁顶推过程支点标高调整方案确定的单步模数搜索合成法

Single-step modulus search and composition method for determining the scheme of support elevation adjustment during girder launching with vertically varied curvatures

针对穷举法计算量太大、试算法需要丰富经验的不足,研究变曲率竖曲线梁顶推过程中支点标高调整方案确定的新方法。基于相关假定,给出各支点处梁体强迫位移、顶推过程支点标高(含初始标高、调整后标高)及其调整约束条件等顶推关键要素的数学表达,明确支点初始标高的设置方法。在建立穷举法标高调整向量数学表示及其最优(或较优)标高调整方案寻找流程的基础上,基于先粗后精分级寻优思路提出计算量较穷举法大为减少的两步穷举法。考虑顶推过程支点标高调整方案确定中标高值优化精细程度的工程意义(或者优化标高值工程上的可变动性),提出"标高模数"概念,明确搜索策略,采用"先单倍模数搜索,再最大程度合并"的思路建立单步模数搜索合成法。算例分析比较两步穷举法、单步模数搜索合成法的计算耗时与结果等,明确单步模数搜索合成法是确定变曲率竖曲线梁体顶推支点标高调整方案的较佳方法。

Aiming at the large calculation amount of exhaustion method and competent experience requirement of trialand-error method,a new scheme is studied for support elevation adjustment during girder launching with vertically varied curvatures. Based on several relevant assumptions,some key elements,such as girder forced displacement at each support,support elevation( including both initial and adjusted value) during launching and constraint conditions for elevation adjustment,are expressed in mathematical formulas. Also the method of determining initial elevation is given.After building the mathematical expression of elevation adjustment vector and the searching flow chart for optimal or better elevation adjustment scheme of exhaustion method,a two-step exhaustion method is presented based on the optimization principle of 'step by step from roughness to fineness'. Considering the engineering significance of accuracy degree or the engineering margin for the optimal elevation in support elevation adjustment during launching,the concept of 'elevation modulus'is proposed. With clear searching strategy,a single-step modulus search and composition method is established based on the thought of'first searching with single modulus and then composting to the maximum degree'.Computation time of the two-step exhaustion method and the single-step modulus search and composition method are compared by numerical examples. The results indicate that the single-step modulus search and composition method is better for determining the scheme of support elevation adjustment during girder launching with vertically varied curvatures.