浅埋偏压隧道变形特征及施工方案优化  

Deformation Characteristics of Shallow Tunnel under Unsymmetrial Loading and Its Optimization of Construction Schemes

作　　者：王智超[1] 徐伟[1] 张学兵[1] 沈明燕[2] 旷杜敏 

机构地区：[1]湘潭大学岩土力学与工程安全湖南省重点实验室(培育),湖南湘潭411105 [2]湖南科技大学土木工程学院,湖南湘潭411201

出　　处：《湘潭大学自然科学学报》2017年第3期34-41,共8页Natural Science Journal of Xiangtan University

基　　金：国家自然科学基金项目(51308485);湖南省自然科学基金项目(12JJ4006;2016JJ2133)

摘　　要：为研究隧道洞口浅埋偏压段的变形特征,采取现场隧道变形监测和围岩室内三轴率敏性试验相结合,建立隧道围岩的弹黏塑性本构模型.通过有限元软件ABAQUS的UMAT子程序开展了隧道变形三维弹黏塑性数值分析,探讨了隧道在三种开挖工法下的拱顶沉降、水平收敛位移、围岩最小主应力及围岩塑性区分布规律,以此确立合理有效的施工工法.研究结果表明:预留核心土法、三台阶法以及上下台阶法这三种施工工法引起的地表沉降,其深埋侧分别是浅埋侧的2.01,1.48,1.83倍,边墙两侧最小主应力则分别相差0.11,0.29,0.05 MPa,表明偏压隧道的应力场和位移场在开挖支护过程中呈现出不对称分布的特点;选出适宜的施工工法为上下台阶法,采用此工法可以使拱顶沉降及地表沉降减少11.7%~22.1%,而且在施工过程中支护结构受力最为合理,有利于偏压隧道的长期稳定.In order to invest igate the deformat ion character ist ics of por tal section of shal low tunnel under unsymmet rical loading, the f ield moni toring and indoor triaxial rate sensitivi ty test were both car ried out to establ ish the elast ic-viscoplast ic const i tut ive model of tunnel surrounding rock. The three dimensional elas-t ic-viscoplast ic deformat ion numer ical analysis of tunnel was realized by the UMAT subrout ine implemented into the fini te element sof tware such as ABAQUS. The vault settlement , horizontal convergence displace-ment , minimum principal stress, and distribution regulari ty of plast ic zone of surrounding rock were com-pared under three kinds of tunnel const ruct ion schemes, and a most reasonable and ef fect ive const ruct ion scheme was determined final ly. The resul t shows that the ground surface set t lement of deep-buried tunnel side caused by tunnel const ruct ion of core-soi l excavation method, t ri-bench excavation method, and bench cut method are 2. 01, 1. 48,and 1. 83 times than that of shal low-buried tunnel side, respect ively; the mini -mum principal stress of tunnel wal l on both sides respect ively di f fers 0. 11, 0. 29,0. 05 MPa under three kinds of tunnel const ruct ion schemes. It indicates that the stress and displacement field of unsymmet r ical loading tunnel presents asymmetric distribution characterist ics during the process of the excavation support . The tunnel const ruct ion scheme of bench cut method is proposed as an appropriate opt imizat ion scheme, be-cause the vaul tsett lement and ground set t lement of unsymmet rical loading tunnel can decrease 11. 7% -22. 1 %,and its suppor t ing pressure will be mos t reasonable dur ing the const ruct ion process. So it is beneficial to maintain the long-period stabi l i ty of unsymmet r ical loading tunnel.

关 键 词：浅埋偏压隧道 施工工法 现场监测 室内三轴试验 弹黏塑性本构 

分 类 号：U455[建筑科学—桥梁与隧道工程]