摘要
大量实测资料及试验表明,地表下沉曲线以及拱顶沉降、中墙应力、围岩塑性区分布具有明显的非对称性,即具有偏态性。对于此偏态问题,国内外学者以Weibull分布作为影响函数建立预计方法,利用地表移动的最终结果拟合,给出了偏态下沉预计的经验公式,但对偏态形成的原因却没有深入分析。结合城市浅埋大跨连拱隧道工程实例,针对已成功应用的CD,CRD工法等非对称开挖方法,根据现场监测数据进行反分析,采用数值模拟方法,对开挖沉降曲线的偏态性及其内在机制进行了深入研究。在此基础上,提出采取压浆弥补地层损失,设置隔水帷幕限制偏态沉降范围,非等参支护调节时空效应等具体防范对策;监控量测中,应耦合建构筑物的健全度,评估施工环境影响风险阀值,拟定控制标准,保证地下管线和地面建构筑物的安全。
Many practical measures indicate that the settlement distribution of ground surface and vault,plastic zone in surrounding rock masses,and stresses in the middle wall are remarkably asymmetrical,i.e. skewness distribution. The position of maximum subsidence always lies toward the initial excavation side and the ground settlement curve is steeper on the initial excavation side while gentler in the subsequent side. A few empirical formulae such as the one based on the Weibull distribution by fitting the ground settlement curve have been proposed to estimate the skewness. However,the mechanisms of the skewness settlement have not been reasonably analyzed. The issue through a detailed case study based on monitoring data,numerical simulation and back analysis for an urban shallow large-span double-arch tunnel,which is constructed using CD/CRD methods,is considered. Furthermore,specific countermeasures were proposed,i.e. grouting to ground loss,stopping-water-heavy-curtain to limit range of skewness,non-isoparametric supporting to regulate time-space effect. To guarantee the safety of the underground pipelines and ground buildings,risk threshold values and control criteria are put forward based on an integrated approach of time-space effect and structural integrity level.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第S1期3203-3209,共7页
Chinese Journal of Rock Mechanics and Engineering
基金
中国科学院“百人计划资助项目”
关键词
隧道工程
城市浅埋大跨连拱隧道
地表沉降偏态性
防范对策
tunnelling engineering
urban shallow large-span double-arch tunnel
skewness of ground settlement
countermeasure
