地铁振动荷载作用下隧道周围饱和软黏土分形研究

A study on the fractals of saturated soft clay surrounding subway tunnels under dyanmic loads

以上海地铁2号线静安寺站-江苏路站区间隧道周围饱和软黏土为研究对象,在现场监测和室内GDS(多功能循环三轴试验系统)试验的基础上,利用压汞仪微观试验研究方法,对隧道周围饱和软黏土微结构进行定量研究。研究结果表明,孔隙分形维数在隧道不同深度处的变化规律可以用不同的循环应力比CSR来体现。随着深度的增加,循环应力比CSR也随之增大,分形维数随着循环应力比CSR的增加先是下降然后又逐渐上升。研究成果为软土地区饱和软黏土中地铁隧道轴线变形和隧道经过区域地面沉降作了有价值的探索,也为探讨地铁行车荷载作用下饱和软黏土的破坏机制、造成地铁隧道轴线变形与地面沉降研究提供一定的理论支持。

The saturated soft clay around the tunnel section from Jing＇ an Temple Station to Jiangsu Station of the Shanghai No.2 subway line is studied. With field observation and laboratory GDS and mercury intrusion po＇rosimetry, a quantitative study is conducted on the microstructure of the saturated soft clay. The study reveals that the fractal dimension at a given depth may be embodied by the corresponding CSR. With the increase in depth, the CSR increases correspondingly, and the fractal dimension first increases and later decreases. This study is valuable for the subway axial deformation and for the ground settlement in the saturated soft clay, and prvodes theoretical support for damage mechanics, subway axial deformation and ground settlement under subway vibration load.