浅覆土大断面盾构隧道横截面受力变形特性研究

Analysis on inner force and deformation characteristics of large shallow shield tunnel cross section

采用三维荷载—结构模型分析不同覆土厚度和侧向土压力系数k0条件下盾构隧道横截面内力和变形的变化规律。研究结果表明:覆土较浅情况下,隧道收敛变形呈"竖鸭蛋"状;覆土较深情况下,隧道收敛变形呈"横鸭蛋"状。覆土深度为9m时,隧道水平收敛变形等于竖向收敛变形,隧道呈圆形。随着覆土深度的增加,变形形式由"竖鸭蛋"变为"横鸭蛋"的临界k0值逐渐增大。管片轴力均为压力,在不同覆土深度和k0情况下,管片轴力和弯矩极值出现位置相同,但覆土深度不同时,弯矩极值的符号不同。

In this paper,a 3D load-structure model was created to investigate the influence of thickness of burial soil and the lateral earth pressure coefficient on the internal forces and deformations of tunnel segment. The study results indicated that small overburden led to a 'standing duck egg ' deformation. In the case of large overburden,the deformation of the tunnel segment became a 'lying duck egg'. The tunnel was circular with the overburden of 9m. With the increase of overburden,the k0 of tunnel deformation form changed from 'standing duck eggs'to 'lying duck egg'increased gradually. The extremum of axial force and bending moment of tunnel segment appeared at the same position under different overburden and k0. The positive and negative bending moment extremum turned different under different overburden.