中小直径盾构隧道管片衬砌结构纵向抗弯刚度特性研究

Experimental Research on Longitudinal Bending Stiffness Characteristics of Segment Lining Structure of Small and Medium Diameter Shield Tunnels

对于城市轨道交通以及市政管道而言,中小直径盾构隧道具有天然的优势,近年来取得了快速发展。然而,随着地质条件及周围环境日趋复杂,其纵向差异沉降对其结构安全产生了显著影响。为研究中小直径盾构隧道的纵向抗弯刚度特性,采用相似模型试验,考虑环向与纵向接头的影响,开展盾构隧道结构纵向抗弯性能试验。对隧道竖向变形、抗弯刚度有效率进行分析,提出适用于确定中小直径盾构隧道纵向抗弯刚度有效率的经验修正公式,并给出关键参数的取值范围。研究结果表明:(1)盾构隧道管片衬砌结构在受荷后刚度会发生变化,刚度的变化实质为受荷后管片衬砌结构的变形引起;(2)直径为4.2m和6.0m的盾构隧道结构纵向抗弯刚度有效率合理取值范围分别为0.194~0.352和0.162~0.311;(3)引入纵向抗弯刚度修正系数对徐氏模型理论公式进行修正,经试验结果确定直径为4.2 m和6.0 m的修正系数范围分别为0.7~1.4和0.8~1.6。

For urban rail transit and municipal pipelines,shield tunnels of small and medium diameters have natural advantages and developed rapidly in recent years.However,with the increasingly complex geological conditions and surrounding environment,the longitudinal differential settlement poses great influences on structural safety.In order to study the characteristics of longitudinal bending stiffness in small and medium diameter shield tunnels,the longitudinal bending performance test of shield tunnel structure is carried out based on similarity model theory,in which the influences of circumferential and longitudinal joints are taken into account.The vertical deformation and bending rigidity of the shield tunnel are analyzed,and the empirically modified formula is put forward for the efficiency of the longitudinal bending rigidity in small and medium diameter shield tunnels,and the range of critical parameters is given.The results show that:(1)The stiffness of the segment lining structure changes under loads,which is caused by the deformation of segment lining structure after loading.(2)For shield tunnels of 4.2m and 6m diameter,the reasonable effective efficiency of the longitudinal bending rigidity is 0.194-0.352 and 0.162-0.311,respectively.(3)The modified coefficient of longitudinal bending stiffness is introduced to modify the theoretical formula of Xu's model.According to the test results,the ranges of modified coefficient for shield tunnels of 4.2m and 6m diameter are 0.7-1.4 and 0.8-1.6 separately.