摘要
花岗岩残积土层基坑施工极易引起下方盾构隧道产生上浮变形和结构病害。该文依托深圳地区深基坑长距离上跨新运营地铁隧道施工案例,建立三维有限元模型,研究了深基坑开挖引起下方盾构隧道上浮量和水平收敛变化规律,并对衬砌结构纵向受力和病害相关性进行分析。结果表明:基坑卸载引起的隧道变形以整体上浮为主,断面变形为辅。采用跳仓开挖并对隧道拱顶上方土体进行抽条加固后,隧道上浮量平均减小了14.4%,围护结构侧移减小了49.1%。上方卸载造成的盾构隧道病害主要为集中于拱顶的环缝掉块,分析原因为拱顶环缝接头在弯矩-剪力共同作用下,内侧混凝土产生压剪裂缝并逐渐发展。
The construction of foundation pits in granite residual soil layers is prone to causing upheaval deformation and structural damage in shield tunnels below.Based on the engineering case of a newly operated metro tunnel collinear with the above long-distance deep foundation pit in Shenzhen,a three-dimensional finite element model was established to investigate the variation law of the heave and horizontal convergence of the shield tunnel caused by the deep foundation pit excavation.The correlation between the longitudinal stress of the lining structure and the damage was analyzed.The results indicate that the tunnel deformation caused by foundation pit unloading is primarily vertical heave,accompanied by slight section deformation.After adopting the jump excavation method and the stripped soil reinforcement above the tunnel crown,the average tunnel heave is reduced by 14.4%,and the lateral displacement of the envelop enclosure is reduced by 49.1%.The shield tunnel damage caused by the above unloading is mainly the spalling at the circumferential joints of the tunnel crown.The reason is that the compressive shear cracks occur and expand on the intrados of the circumferential joints of the tunnel crown under the combined action of bending moment and shear.
作者
刘继强
朱旻
郝琨
陈登伟
陈湘生
LIU Jiqiang;ZHU Min;HAO Kun;CHEN Dengwei;CHEN Xiangsheng(China Railway Southern Investment Group Co.,Ltd.,Shenzhen,Guangdong 518060,China;College of Civil and Transportation Engineering,Shenzhen University,Shenzhen,Guangdong 518060,China;Key Laboratory of Coastal Urban Resilient Infrastructure,Ministry of Education,Shenzhen University,Shenzhen,Guangdong 518060,China;Electrical Engineering Co.,Ltd.of CTCE Group,Bengbu,Anhui 233000,China)
出处
《中外公路》
2024年第3期202-210,共9页
Journal of China & Foreign Highway
基金
国家自然科学基金资助项目(编号:52008263,51938008,52090084)
中国中铁股份有限公司2020年度科技开发计划重点项目(编号:2020-重点-14)。
关键词
盾构隧道
基坑开挖
上浮
结构病害
数值计算
花岗岩残积土
shield tunnel
foundation pit excavation
heave
structural damage
numerical calculation
granite residual soil
