武汉轨道交通8号线田田绿化广场工程场址下伏深厚软土,深大异形基坑开挖对周边京广铁路、城市高架等重要建构筑物的影响需开展专题研究。基于基坑支护设计方案,通过三维有限元动态过程数值模拟,研究了基坑开挖对周边既有建构筑物的影响,得到以下主要结论:结合支护结构及周边计算成果,经与相关规范中既有建构筑物变形允许值的比较,有针对性地提出了重点区域的加固方案;对基坑工程实际开挖支护过程进行了持续监测,结果表明临近建构筑物变形在基坑开挖至底标高时快速达到最大并趋于稳定,专项加固方案可有效控制重点部位建构筑物变形指标,验证了基坑支护及专项加固方案的有效性,保障了该深厚软基区深基坑施工顺利进行。精细化数值模拟可有效克服现有规范在评估新建和既有工程相互复杂影响时的局限性,有助于为优化工程方案提供必要的技术支撑。

As deep soft soil lies under the site of Tiantian green square project of Zhuyeshan station of Wuhan Metro Line 8,special research is required to investigate the influence of large irregular deep foundation pit excavation on the surrounding Beijing-Guangzhou railway,urban viaduct and other important buildings.Based on 3D finite element dynamic numerical simulation of the excavation and support scheme,we proposed some targeted reinforcements for key parts by comparing the numerical result with the allowable deformation in sepcifications.Moreover,we monitored the excavation and support process of the actual project,and found that the deformation of adjacent buildings and structures quickly reached the maximum value and tended to be stable when the foundation pit is excavated to the bottom elevation.Special reinforcement scheme could effectively control the deformation of surrounding key structures,which verified the effectiveness of the excavation and support scheme and in the meantime ensured the smooth construction of deep foundation pit in deep soft soil area.Refined numerical simulation could overcome the limitations of relevant industry specifications in evaluating the interaction between new construction and existing complex projects,and also could provide a necessary technical support for rational optimization of engineering schemes.