【摘要】 研究目的:上方堆载是诱发超浅埋地铁盾构隧道过大沉降、过大椭圆度和隧道出现开裂等病害的重要外部因素。本文详细介绍了某盾构隧道在两次堆卸载过程中发生的沉降和出现的隧道病害现象,通过开展隧道病害现状调查,结合隧道沉降和椭圆度监测数据分析,应用三维精细模型分析盾构隧道结构受力及其损伤情况,初步讨论该盾构隧道的结构安全状态。研究结论:(1)盾构隧道沉降规律、椭圆度大小和隧道病害分布规律与隧道上方的两次堆载高度、分布范围以及堆载时间存在显著的相关性;(2)对应于浅覆土3. 7 m部位堆土高达6 m的盾构隧道三维精细仿真分析结果表明,环向连接螺栓受力处于弹性阶段,纵向接缝张开量在预警值1 mm内,拱部和道床下方管片出现部分受拉裂缝,仿真结果与现场调查发现的隧道裂缝分布规律基本相吻合;(3)本研究成果可为类似工程控制隧道上方超载和判断盾构隧道结构安全提供参考,并可为后续即将进行的邻近深大基坑设计及施工控制提供基础资料。更多还原

【Abstract】 Research purposes: Upside surcharge is an important external reason for which induces excessive settlement,large elliptical variation and disease of subway shield tunnels. This paper introduces the settlements and diseases during the two soil stacking loading and unloading processes of an actual project in details. Through the investigation of the current status of tunnel diseases,combined with the analysis of tunnel settlement and ellipticity monitoring data,the safety status of the shield tunnel structure is estimated by using three-dimensional finite element detailed model to calculate the structural stress of shield tunnel.Research conclusions:( 1) There is a significant correlation between the settlement rule,ellipticity magnitude and disease distribution of the shield tunnel and the two soil stacking heights,distribution ranges and loading time above the tunnel.( 2) The three-dimensional detailed simulation results of the shield tunnel with the maximum stacking height of6 m regarding to covering soil height of 3. 7 m show that circumferential joint bolt is in the elastic stage,the longitudinal joint opening magnitude can be restrained within 1 mm,and concrete tensile cracks of several segments below the arch and the track bed are induced. The simulation results are basically consistent with that of on-site observation.( 3) The research results can provide reference for the similar project to judge the safety of shield tunnel structure and to control the upside surcharge. It may also provide important basic data for the upcoming adjacent pit design and construction control.更多还原