摘要
无水砂卵石地层力学性质不稳定,卵砾石含量高,颗粒之间空隙大,无黏聚力,盾构在此条件下掘进,渣土很难被改良成"塑流性状态",盾构推力、扭矩大且变化异常,刀盘、刀具及螺旋输送机磨损严重,盾构掘进效率低且时常发生开挖面失稳、地表塌陷等事故。结合北京地铁十号线二期7标的工程实践,提出了"分区注入"的施工方法。即根据刀盘上的7个注入孔的位置分布情况,通过外侧孔注膨润土泥浆,而中心区域注泡沫,中间的过渡区混合注入,膨润土泥浆与泡沫的配比可以根据不同工况做实时调整。该技术的成功应用,保证了盾构机长距离在砂卵石地层中连续高效掘进。
Gravel strata is characterized by the unstable mechanical properties, high content of gravel, large space among gravels and no cohesion. Tunneling in the strata, where the soil residue is very difficult to condition into flow plastic state, is hindered by large shield driving and torque as well as abnormal variation, which causes severe wearing of the screw con- veyor. At the same time, the tunnel face becomes unstable and ground collapse accidents appear frequently. This paper proposes partition injection for soil conditioning based on the practical engineering in Lot7 line 10 of Beijing Metro; there are 7 injection ports in the cutter head, therefore, different partition injection areas are alternative, the outside of cutter head is used for bentonite slurry injection, the central area is used for foam, and the intermediate area for both with the mixture ratio of bentonite slurry and foam can be changed in accordance to different strata. The successful application of this method can guarantee high efficiency continuous excavation for TBM in waterless gravel strata.
出处
《铁道建筑技术》
2013年第4期4-7,共4页
Railway Construction Technology
关键词
分区注入
渣土改良
盾构施工
无水砂卵石地层
partition injection
soil conditioning
shield tunneling
waterless gravel strata
