下穿既有建筑期间盾构施工参数分析

Analysis on shield construction parameters during down-crossing existing buildings

以杭州地铁二号线为对象,研究在盾构下穿既有建筑过程中盾构施工参数及姿态参数的变化规律.基于盾构掘进参数及现场实测数据发现,在盾构到达既有房屋前,盾构土舱压力大于静止侧向土压力会致使房屋隆起变形;盾构刀盘回转方向与土舱压力具有相关性,当盾构刀盘顺时针回转时,左侧土压力大于右侧土压力,反之亦然.为降低盾构刀盘挤压效应,避免房屋过大隆起变形,盾构经历多次停机;反向回转盾构切口可调整盾体回转角;设定下区千斤顶推力大于上区千斤顶,其差值产生的纠偏力矩可有效地调整盾构俯仰角.

The law of shield construction parameters and attitude control are presented and interpreted by investigating the Hangzhou metro Line-2tunnel project.The monitored construction data and field measurements show that the heave of buildings occurs when the earth pressures of chamber are larger than the horizontal earth pressures in-situ and the cutter-head is in front of the buildings.There are certain relationships between the rotating direction and the earth pressures of chamber.When the cutter-head rotates clockwise,the monitored left earth pressures are significantly larger than the right earth pressures,and vice versa.Shield went doun for several times beneath shield driving in order to reduce the compressing effect caused by cutter-head and avoide the larger heave of the buildings.The opposite rotating direction of cutter-head helps to adjust the rolling of shield body.Set that the thrusts of down zone jacks is larger than that of upper zone jacks,the correction moments caused by the difference will effectively adjust the pitching angels during tunnlling in soft soils.