摘要
随着城市地下空间的不断开发利用,基坑近接施工对地铁隧道等地下工程结构变形影响问题频繁出现,加强分析基坑近接施工对紧邻地铁隧道结构变形影响及其控制优化设计是目前地下工程与岩土工程研究领域的热点和难点问题之一。以武汉市新长江香榭东沙基坑为例,采用基于小应变土体硬化(HSS)模型的有限元方法模拟分析和实时监控量测,开展基坑支护优化设计,制订坡顶卸土减载、大直径钻孔灌注排桩和钢筋砼内支撑为主的综合支护方案和分部对称开挖施工方案,重点分析地铁停车场两侧基坑开挖施工对主体结构的变形影响。结果表明,优化支护结构设计方案,将二层地下室区域的支护桩桩长由原设计方案的23 m延长至28 m,在第一道支撑下方5 m处布置第二道撑;在基坑两侧同步施工开挖过程中,地下主体结构变形主要发生在东西两侧墙位置处,以整体的竖向沉降为主;地铁停车场垂直位移沉降最大值为-1.1~9.5 mm,满足路基沉降要求;停车场两侧基坑需同步开挖、同步架设支撑。其研究成果可为城市类似基坑近接施工及保障地铁行车安全提供借鉴和参考。
With the rapid development of urban underground space construction,the impact of the construction of foundation pit close to the subway and other underground engineering structures frequently appears.It is one of the hot and difficult problems in the field of underground engineering and geotechnical engineering to strengsthen the analysis of influence of foundation pit constraint on the deformation of adjacent subway tunnel structure and its control optimization design.Taking the foundation pit project of Xiangxie Dongsha,the new Yangtze River in Wuhan as an example,through the finite element simulation analysis and real-time monitoring measurement of the HSS model of small strain hardened soil,this paper has carried out the optimization design of the foundation pit support,and formulated a comprehensive support scheme based on the unloading and load reduction of the slope top,large-diameter bored piles and reinforced concrete internal support,and a construction scheme of partial symmetric excavation.The analysis focuses on the influence of excavation of foundation pits on the deformation of the main structure of the subway on both sides of the subway underground structure.The results show that the design scheme of supporting structure is optimized,and the length of supporting pile in the second basement area is extended from 23 m to 28 m,and the second support is arranged at 5 m below the first support.In the process of synchronous construction and excavation on both sides of the foundation pit,the deformation of the underground main structure mainly occurs at the positions of the east and west sides of the wall,with the overall vertical settlement as the main;the vertical displacement of the subway parking lot is analyzed,and the maximum settlement is-1.1-9.5 mm,which meets the requirements of subgrade settlement.The foundation pits on both sides of the parking lot need to be excavated and supported synchronously.The research results can provide reference for the construction of similar foundation pits in cities and the safety of subway traffic.
作者
彭小丹
徐杨青
杨龙伟
Peng Xiaodan;Xu Yangqing;Yang Longwei(Wuhan Metro Group Co.Ltd.,Wuhan,Hubei 430070;Wuhan Design&Research Institute Co.,Ltd.,China Coal Technology&Engineering Group,Wuhan,Hubei 430064)
出处
《资源环境与工程》
2023年第3期334-343,共10页
Resources Environment & Engineering
基金
中煤科工集团有限公司科技创新创业项目(2022-2-MS006)资助。
关键词
地铁隧道
基坑开挖
近接施工
变形分析
数值模拟
metro tunnel
foundation pit excavation
adjacent construction
deformation analysis
numerical simulation