兰州地铁下穿黄河砂卵石地层中盾构刀具破岩的数值计算

Numerical calculation of shield cutter in sandy pebble stratum of Yellow River for Lanzhou Subway

针对兰州地铁首次盾构下穿黄河砂卵石地层,选用线弹性模型和扩展的线性Drucker-Prager塑性模型模拟卵石材料的本构关系,建立盾构刀具在砂卵石地层的破岩的数值计算模型,分析了刮刀切削速度为0.6 m/s、0.8 m/s、1.0 m/s、1.2 m/s;切削深度为6 mm、9 mm、12 mm、15 mm、18 mm;切刀间距为12 cm、16 cm、20 cm、24 cm;刀具前角为10°、15°、20°、25°的几种不同情况下对黄河砂卵石地层的破岩效果。根据计算结果得到刮刀前角为20°时卵石的等效应力发生突增提供破岩应力,破岩效果最好;另外还分析了滚刀间距分别为8 cm、12 cm、16 cm、20 cm、25 cm、30 cm、36 cm时的破岩效果,在滚刀间距取12～16 cm之间时破岩效果最佳。

Aiming at the Yellowstone sand-pebble formation under the first shield of Lanzhou Subway,this paper selected a linear elastic model and extended the linear Drucker-Prager plasticity model to simulate the constitutive relationship of pebble material and established the numerical calculation model of shield rock breaking in rock-pebble formation.The rock breaking effect on the Yellow River pebble stratum in several different situations was analyzed when Blade cutting speed was 0.6 m/s,0.8 m/s,1.0 m/s,1.2 m/s;cutting depth was 6 mm,9 mm,12 mm,15 mm,18 mm;cutter spacing was 12 cm,16 cm,20 cm,24 cm;The rake angle was 10°,15°,20°,25°.According to the calculation results,when the blade rake angle is 20°,the pebble equivalent stress suddenly increases to provide rock breaking stress,and the rock breaking effect is the best.In addition,the rock breaking effect was analyzed when the hob pitch is 8 cm,12 cm,16 cm,20 cm,25 cm,30 cm and 36 cm respectively.The rock breaking effect was the best when the hob pitch was between 12 cm and 16 cm.