河底地铁盾构隧道管片受力特征分析

穿河盾构隧道相比其它区段盾构隧道的工程地质和水文地质条件更为复杂,特别在我国南方地区,季节性降水量大,地表及地下水位变化明显。针对穿河盾构隧道富水软粘土地层,文章以佛山地铁2号线某区间穿河盾构隧道管片为研究对象,利用Abaqus有限元软件,采用梁-弹簧模型对受力管片进行数值计算分析,并与现场试验所测得的管片轴力进行验证。结果表明,现场测试管片受到的土压力略小于采用全覆土压方法的计算值;盾构隧道周围的水压对管片内力的影响较大,穿河盾构隧道即使上部土层透水性差,在管片设计时也要考虑岩层中裂隙水和承压水存在的可能,且为安全考虑,作用在管片上的土压可按全覆土压来计算。

Analysis of the Mechanical Behavior of Segments of the Shield-driven Metro Tunnel beneath River Bottom

Compared with other sections of a shield tunnel,the engineering geology and hydrogeological conditions of the shield tunnel section passing through river are more complex,especially in southern China where the seasonal precipitation is large,the surface and underground water levels change obviously.Taking certain section of the shield tunnel on Foshan metro line 2 as the research object,it carries out a numerical analysis on segments using⁃Abaqus finite element software based on a beam-spring model,and verifies with the measured axial forces of seg⁃ments.The results show the earth pressure on segment is slightly smaller than that calculated by the full-covered earth pressure method;water pressure around the shield tunnel has great influence on internal force of segment,the fissure water and confined water in rock stratum should be taken into account in the design of segment even if the rock layer above shield tunnel is poor in water permeability,and the earth pressure acting on segment is calculated with the full-covered earth pressure for the sake of security.