Abstract:

In order to reduce the occurrence of shield construction disasters caused by geological factors and to achieve early detection and prevention, the influences of soft and hard rock strata, fault and fracture zone, rock strata attitude, karst, spherical weathered body and other adverse geological bodies on the threedimensional displacement of shield tunnel are simulated by FLAC3D; and the threedimensional deformation display method developed by domestic and foreign scholars is used to show the response characteristics of tunnel excavation strata. The results show that: (1)When shield tunneling from soft rock to hard rock, the trend line of displacement vector decreases; on the contrary, the trend line of displacement vector increases.(2)With the increase of width of fault and fracture zone, the trend line of displacement vector presents regular changes.(3) The change of alpha angle when the geological interface inclines is earlier than that when the geological interface is vertical.(4)The greater the strength difference between adjacent strata, the more obvious the trend line of displacement vector.(5)The larger the size of karst and spherical weathered bodies, the greater the variation range of displacement vector trend line.

Key words: shield tunnel, advance geological forecast, numerical simulation, displacement vector trend line