受基坑开挖卸荷影响连续箱梁悬浇施工优化

Optimization of continuous box girder cantilever casting construction technology affected by foundation pit excavation and unloading

针对连续箱梁悬浇工艺优化方法在实际工作过程中箱体挠度和弯矩很难控制在规定范围内,分析竖向剪应力和横向剪应力的分布状态,探究连续箱梁悬浇工艺不同施工阶段的演化规律,计算剪应力贡献比和箱梁所受到的附加负荷。利用剪应力分析结果确定连续箱梁悬浇工艺的挠度最大值和弯矩最大范围,并分析了箱梁所受到的附加负荷,确定引入曲率,建立平衡公式,构建地基空间模型。安装吊篮钢壳,在满足检验体系要求后,布置剪力钉,根据混凝土配比、凝固时间和桥体沉降率实现顺序浇灌,在充分考虑实际环境,包括气温、湿度与土壤条件等因素后,检验悬梁工艺强度。研究结果表明,基坑开挖卸荷影响的连续箱梁悬浇工艺优化方法计算结果与数值模拟结果基本保持一致,当荷载达到6 MPa时,弯矩最大变化值仅为0.10 mm,不同宽度和深度的箱体挠度低于8 mm,弯矩始终在-120~120 kN/m,具有极强的优化效果。

In view of the fact that the box deflection and bending moment are difficult to control within the specified range in the actual work process of the optimization method of continuous box girder cantilever casting process,the distribution state of vertical shear stress and transverse shear stress is analyzed,the evolution law of the continuous box girder cantilever casting process in different construction stages is explored,and the contribution ratio of shear stress and the additional load on the box girder are calculated.Based on the results of shear stress analysis,the maximum deflection and the maximum range of bending moment of the continuous box girder cantilever casting process are determined,and the additional load on the box girder is analyzed.The introduced curvature is determined,the balance formula is established,and the foundation space model is constructed.Install the steel shell of the hanging basket.After meeting the requirements of the inspection system,arrange the shear nails,and realize the sequential pouring according to the concrete mix ratio,setting time and bridge settlement rate.After fully considering the actual environment,including temperature,humidity,soil conditions and other factors,inspect the technological strength of the suspension beam.The research results show that the calculation results of the optimization method of the continuous box girder cantilever casting process affected by the excavation unloading of foundation pit are basically consistent with the numerical simulation results.When the load reaches 6 MPa,the maximum change value of the bending moment is only 0.10 mm,the box deflection of different widths and depths is less than 8 mm,and the bending moment is always-120~120 KN/m,which has a strong optimization effect.