无水砂卵石地层盾构常压开仓脱困技术

NORMAL PRESSURE OPENING AND DIFFICULTY RELIEF TECHNOLOGY OF TBM IN ANHYDROUS SANDY PEBBLE STRATUM

北京某地铁隧道采用交叠盾构法施工。由于下层盾构隧道加固影响,需断续掘进,每次掘进有数天停机过程。在一次停机40 h后,对盾构机进行保压时,发现刀盘抱死。此时盾构机埋深为12.3 m,所处地层为卵石(5)。为保证掌子面土体稳定性,采取土舱清理与开挖面支护同期进行的措施。在完全清空土舱后刀盘试转,刀盘外周行程达20 cm后停止转动,标志着刀盘脱困成功。之后自下而上撤出掌子面支护措施,同时用聚氨酯泡沫袋和膨润土泥浆回填土舱,土舱填满后关闭人舱门,继续加入膨润土泥浆,建立土压后盾构机试掘进,完成该次脱困处理。

A subway tunnel in Beijing is constructed by overlapping shield method, due to the influence of lower shield tunnel reinforcement, the construction needs to be stopped for several times for several days. After 40hours of a shutdown, when maintaining the pressure of shield machine the cutter head torque reaches the maximum,the cutter head is locked. when the machine is buried deeply 12.3 m, in formation for pebble 5. Continuous construction and emptying of earth bin mud cake, at the same time, support the face of the tunnel. After completely emptying the soil bin, try to turn the cutter head, and stop rotating after the peripheral stroke reaches 20 cm, which marks the success of the cutter head. Then the support measures from the bottom to the top were withdrawn from the support surface. At the same time, polyurethane foam bags and bentonite slurry were used to fill the soil bin. After filling the earth bin, the hatch door was closedm, and the bentonite slurry was added to build the earth pressure to shield the machine.