基于EDEM的砂卵石地层盾构刀具磨损特征研究

Wear characteristics of shield cutters in sand-pebble strata based on EDEM

为揭示砂卵石地层土压平衡盾构典型刀具的磨损特征,指导该地层中盾构刀具的设计、布置等关键问题。采用室内三轴试验及数值离散元软件(EDEM)仿真分析,标定了颗粒-刀具磨损接触参数。依托北京新机场“磁各庄-1号风井”砂卵石盾构工程,构建了砂卵石地层EDEM数值盾构模型,可视化了砂卵石地层土压平衡盾构中典型刀具(楔犁刀、刮刀)的磨损特征,通过实际工程对模型进行了验证。研究表明:(1)以犁松原状砂卵石土为目的的楔犁刀具是掘进主切削刀具,表现为刀头合金表面以及刃角处连续的摩擦磨损形式,磨损量较大;(2)以剥落输排为目的刮刀主要表现为刀身迎土面以及刀头合金表面随机的点蚀磨损,磨损量较小;(3)刀盘径向刀具的磨损量随轨迹半径及刀体高度的增加而增大,同轨迹上高刀的磨损系数高于低刀,高刀对低刀的磨损有保护作用;刀盘径向刀具和环向刀具的“梯次化”布置可延长盾构单次连续掘进距离。

In order to reveal the wear characteristics of typical EPB shield cutters in sand–pebble strata and guide the design and layout of shield cutters in the strata,the particle-cutter wear contact parameters are calibrated through the indoor triaxial tests and discrete element software simulation analysis of EDEM.An EDEM numerical shield model for the sand–pebble strata is established based on the Beijing New Airport Line section from Cigezhuang station to No.1 air shaft in the sand–pebble strata.The wear characteristics of typical rippers and scrapers during soil pressure balance shield tunneling in the sand–pebble strata are visualized,and the model is verified through an actual project.The research results show that:(1)The rippers for plowing loosely the undisturbed soils are the essential cutting tools with an excessive wear,and the manifestation is continuous friction and wear on the alloy surface of the cutting head and at the blade edge.(2)The scraper for the purpose of stripping and discharging is mainly characterized by random pitting wear on the soil surface of the blade body and the alloy surface of the blade head,and the wear amount is small.(3)The wear amount of the radial cutter of the cutterhead increases with the increase of the radius of the trajectory and the height of the cutter body.The wear coefficient of the high cutter is higher than that of the low cutter on the same trajectory,and the high cutter has a protective effect on the wear of the low cutter.The gradient arrangement of cutters can extend the single continuous excavation distance and improve the efficiency of shield tunneling in the sand-pebble strata.