摘要
为研究盾构主隧道在机械切削过程中的结构响应,开展了两组平行足尺试验研究。两组试验分别采用钢筋混凝土管片和复合管片,均放置于七环立式试验架中,通过24个外部千斤顶模拟外部水土压力,通过内置盾构机和内支撑体系模拟真实施工过程。通过结合试验现象、结构环内变形和内力、环间变形等分析得到主隧道的破洞响应。试验结果表明,机械法联络通道破洞过程是管片和内支撑共同受力的过程,结构在开洞拆撑后是安全的。结构响应为环、纵向两个方向的内力重分布,分布范围和幅度受到衬砌结构性质,切削推力和内支撑刚度等的影响。在内支撑辅助受力的情况下,最危险工况为拆撑工况,弯矩增量达到40~60 kN·m。始发工况下受到较大影响的为第4环的切削侧,弯矩变化量达到50 kN·m。危险截面主要集中在第4环的切削侧和第3、第5环的顶部和腰部位置。纵向影响范围基本集中在中间三环到五环。内支撑在切削过程中承担主要的荷载变化。
In order to study the structural safety of the linings of the main tunnel during mechanized cutting, two full-scale tests on segmental tunnel rings are carried out. The specimen each consists of seven rings. One of them is assembled by reinforced concrete segments, whereas the others by composite segments. 24 hydraulic jacks per ring provide external forces, simulating water and soil pressure. A shield machine is used to cut the segments, simulating the initial process of mechanized drilling of the connecting aisle. The experimental measurements concern the convergence displacements, relative displacements at the joints and strains of concrete and reinforcement. By analyzing the experimental data, the following conclusions are drawn: the tunnel rings together with the inner supports, prescribed before cutting of the segment, carry the additional loads resulting from the cutting process. The structure remains safe after the inner supports are removed. Redistribution of the internal forces occurs in both the longitudinal and circumferential directions. The extent of such a redistribution depends on the type of the segments, cutting thrust and stiffness of the inner supports. The most dangerous load case during the tests refers to removal of the inner supports, and the increment of the bending moment reaches 40~60 kN·m. During the cutting process, the internal forces of the cutting region are greatly changed, and the variable of bending moment reaches 50 kN·m. The most dangerous cross-sections in the longitudinal direction are located at the cutting side of the 4 th ring and the top and waist regions of the 3rd and 5th rings. Redistribution of the internal forces in the longitudinal direction basically occurs in a range of three to five rings nearby the 4th ring. The inner support bears the change of the main loads during the cutting process.
作者
柳献
高一民
张姣龙
朱瑶宏
LIU Xian;GAO Yi-min;ZHANG Jiao-long;ZHU Yao-hong(Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Faculty of Architecture,Civil Engineering and Environment,Ningbo University,Ningbo 315211,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第5期951-960,共10页
Chinese Journal of Geotechnical Engineering
基金
国家重点研发计划项目(2017YFC0805004)。
关键词
机械切削
盾构隧道
复合管片
足尺试验
内力重分布
mechanical cutting
shield tunnel
composite segment
full-scale test
redistribution of internal force