关键词: 盾构参数, 土体位移, 滞后效应, 软土地层

Abstract: Due to excess pore pressure and other factors of deep soft soil, the effect of adjusting the shield parameters on the soil displacement tends to have a certain delay. The adjustment of construction parameter in current session influences more on the soil displacement in later session rather than current. Two same monitoring sections are set up to survey the soil displacement from the shield tunnel in Shanghai soft soil. The effect of each parameter adjustment to the displacement disturbance is analyzed by changing the key shield parameters in different stages during construction. Chamber pressure is adjusted before the shield cutter reaching the monitoring section. Advancing speed is adjusted while shield cutter crosses the monitoring section. Grouting quantity is adjusted when shield tail reaching the monitoring section. Through the monitoring data and the time-effect analysis of the correlation coefficient, it is found that the soil displacement is affected by the disturbances of the pre-adjusted soil pressure when the shield crosses the cross-section, and the soil displacement at the shield tail reflects the squeezing effect caused by advance rate, while the displacement of soil at the late consolidation stage shows the stabilizing effect caused by the increase of the grouting amount when the shield tail prolapse. Therefore, it is not only necessary to deal with the current soil deformation, but also to pay attention to the deformation and prediction of the soil after the adjustment of the parameters so as to avoid the occurrence of accidents due to the delay effect in soft soil.

Key words: shield parameters, soil displacement, hysteresis effect, soft soil stratum