基坑伺服钢支撑分阶段轴力设计及效果分析
顾浩磊1邓向振2,3许炳刚2,3狄宏规4金钰寅4范小叶2,3
Design and Effect Analysis of Phased Axial Force for Servo Steel Bracing in Foundation Pits
GU HaoleiDENG XiangzhengXU BinggangDI HongguiJIN YuyinFAN Xiaoye
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作者信息:1.南京地铁建设有限公司， 210017， 南京
2.中国建筑第八工程局有限公司， 200120， 上海
3.中国建筑第八工程局第三建设有限公司， 210046， 南京
4.上海市轨道交通结构耐久与系统安全重点实验室，201804， 上海
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Affiliation:Nanjing Metro Construction Co., Ltd., 210017, Nanjing, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2023.12.006
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中图分类号/CLCN:TU94+2
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栏目/Col:学术专论
摘要:
目的：在软土地区进行基坑开挖时，可采用伺服钢支撑系统减小基坑围护结构的变形以及对周边环境的影响，但目前对一道伺服支撑仅有一个初始设计值，无法指导开挖过程中支撑轴力的调整，因此需要针对开挖全过程提出相应的伺服支撑轴力设计值。方法：依托南京地铁9号线白云亭路站基坑工程，分别对伺服支撑设置情况不同的全伺服段，部分伺服段断面各开挖步下的伺服支撑轴力进行分阶段优化设计。结合有限元模型与遗传算法，通过有限元模型计算某组伺服支撑设计轴力下的围护结构变形，并通过遗传算法不断生成新的轴力设计值，直至围护结构变形等参数满足设计要求；据此得到不同开挖步下较优的伺服支撑轴力设计值，实现了伺服钢支撑轴力的动态设置。建立了伺服支撑基坑的三维有限元模型，验算优化设计方案下的伺服支撑的变形控制效果及对周边环境的影响。结果及结论：分阶段优化设计得到的伺服支撑轴力可以有效控制开挖过程中围护结构的变形及周边地面沉降。
Abstracts:
Objective: During excavation of foundation pits in soft soil areas, a servo steel bracing system can be employed to minimize deformation of foundation pit retaining structure and the impact on surrounding environment. However, there is only one initial design value for a set of servo bracing, lacking guidance for adjusting bracing axial forces during the excavation process. Thus, it is necessary to propose corresponding SBAF (servo bracing axial force) design values for the entire excavation process.Method: Leveraging the foundation pit project at Baiyunting Road Station of Nanjing Metro Line 9, full servo sections are set for different servo bracing configurations, and for some servo sections, phased optimization design is carried out for the SBAF of the profile at each excavation step. By integrating a finite element model with genetic algorithm, the finite element model is used to calculate the retaining structure deformation under the design axial force of a set of servo bracing. The genetic algorithm continuously generates new axial force design values until the retaining structure parameters including deformation meets the design requirements. Optimal SBAF design values for different excavation steps are obtained, realizing dynamic adjustment of the servo steel bracing axial forces. A threedimensional finite element model of the servo bracing foundation pit is established to assess the deformation control effect and the impact on surrounding environment under the optimized design scheme.Result & Conclusion: The SBAF obtained from phased optimization design can effectively control the retaining structure deformation and land subsidence during excavation process.
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