既有管线影响下地铁车站基坑围护结构局部冷冻加固技术研究
李文
Research on Local Freezing Technology for Metro Station Foundation Pit Retaining Structure under the Existing Pipeline Impact
LI Wen
-
作者信息:中铁十四局集团有限公司， 250014， 济南
-
Affiliation:China Railway 14th Bureau Group Co., Ltd., 250014, Ji’nan, China
-
关键词:
-
Key words:
-
DOI:10.16037/j.1007-869x.2023.07.029
-
中图分类号/CLCN:U231.3； TU472.9
-
栏目/Col:施工技术
摘要:
目的：邻近地铁车站基坑的既有管线往往会导致围护结构施工时基坑的局部支护能力被削弱，进而可能导致基坑失稳。为减小既有管线对基坑围护结构施工造成的影响，需深化研究既有管线影响下基坑围护结构局部采用冷冻加固技术的应用效果。方法：基于济南地铁R1号线大杨庄站附属结构工程，针对既有高压电缆管道影响基坑围护结构产生的一系列施工问题，提出了采用“地下连续墙+钻孔灌注桩”组合支护结构形式，并采用冷冻法进行局部加固的应对措施。建立了该基坑的简化数值模拟模型，对冷冻加固前及冷冻加固后基坑的稳定性进行对比分析，并进一步提出了冷冻层合理的宽度和厚度取值。结果及结论： 冷冻加固前，地下连续墙与钻孔灌注桩因支护刚度差异较大，难以协调二者周边土体的变形，钻孔灌注桩支护处围护结构明显内挤、地面凹陷较大，地下水渗流严重；冷冻加固后形成冷冻隔水墙，钻孔灌注桩处土体的支护刚度增加明显，围护结构周边土体的水平变形、地面沉降大幅降低。增加冷冻加固的土体范围能有效抑制围护桩变形、地面沉降与地下水渗流，但冷冻层的长度与厚度超过一定范围后，其冷冻后效果并不明显。冷冻加固范围取1.5 m厚、9.0 m宽较为合理。
Abstracts:
Objective: The proximity of existing pipelines often weakens the local support capacity of the retaining structures during construction, potentially leading to foundation pit instability. To minimize the impact of existing pipelines on foundation pit retaining structures during construction, it is necessary to conduct an indepth research on the application effect of local reinforcement using freezing technology. Method: Based on the ancillary structure project of Jinan Metro Line R1 Dayangzhuang Station, focusing on the construction problems caused by the presence of highvoltage cable pipelines near the foundation pit retaining structure, a combined retaining structure of ′underground diaphragm wall + bored insitu pile′ is proposed, which adopts the freezing technology for local reinforcement. A simplified numerical simulation model of the foundation pit is established, and the stability of the foundation pit before and after freezing reinforcement is compared and analyzed. Furthermore, reasonable values for the width and thickness of the freezing layer are determined.Result & Conclusion: Before freezing reinforcement, the significant difference in stiffness between the underground diaphragm wall and bored insitu piles made it difficult to coordinate the deformation of the surrounding soil. The support area of bored insitu piles experiences significant internal extrusion, accompanied by substantial land subsidence and severe groundwater seepage. After freezing reinforcement, a frozen cutoff wall is formed, significantly increasing the support stiffness of the bored insitu pile area and reducing the horizontal deformation and land subsidence of the surrounding soil around. Extending the freezing reinforcement range can effectively suppress deformation of the support piles, land subsidence, and ground water seepage. However, when the width and thickness of the freezing layer exceed a certain range, the postfreezing effect becomes less significant. A freezing reinforcement range of 1.5 m in thickness and 9.0 m in width is found to be reasonable.
- 上一篇: 高铁物流运输模式及其可行性
- 下一篇: 5G公专网支撑城市轨道交通“绿智融合”发展
过刊浏览
资料下载
友情链接