北京砂卵石地层盾构先行撕裂刀切削过程数值模拟分析
Numerical analysis of the cutting process of shield tunneling in Beijing sandy pebble formation
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摘要: 为了研究盾构先行撕裂刀在砂卵石地层中切削时的影响因素,利用ABAQUS数值模拟软件,对先行撕裂刀切削砂卵石地层进行数值模拟分析。以北京地铁新机场线06标磁各庄站—1号风井区间盾构工程为依托,分别研究先行撕裂刀在不同切削深度、不同刀间距以及不同切削速度条件下对刀具切削效果的影响,并对数值模拟结果进行分析。经计算可知:在刀具切削深度不变的条件下,随着切削速度的增加,先行撕裂刀的切削力总体保持稳定,同时砂卵石地层的犁松变形区域变化不显著,说明刀具在低速条件下切削土体时,先行撕裂刀切削速度的变化对刀具的切削效果影响不大。在刀具切削速度不变的条件下,随着切削深度的增加,刀具在砂卵石地层切削时刀具的切削力以及地层犁松区域均在不断增大,说明切削深度可以显著影响刀具的开挖效果,砂卵石地层中盾构采用大贯入度的切削模式更有利于提高盾构掘进效率,综合考虑刀具磨损及盾构参数控制的因素,建议可将刀具的切削深度设置为50 mm。先行撕裂刀的刀间距显著影响刀具的切削效率,在刀具切削深度及切削速度不变的条件下,随着刀间距的增大,刀具的切向力显著减小,当刀间距大于170 mm时,撕裂刀的切削力趋于稳定,同时随着刀间距的增大,双刀的共同犁松区域逐渐减小,当刀间距大于160 mm时,双刀的犁松区域开始分离,刀具的切削犁松效果变差,因此,刀具布置时可将先行撕裂刀间距设置为150~160 mm。同时通过研究撕裂刀实际磨损值的变化规律也证明了数值模拟计算结果的正确性。Abstract: In order to study the influencing factors of the shield cutting tool in the sand and gravel stratum, the ABAQUS numerical simulation software was used to carry out a numerical simulation analysis on the cutting of the sand and gravel stratum by the advanced tearing cutter.Based on the shield tunneling project from Cigezhuang Station to 1# ventilation shaft of Beijing Metro New Airport Line, the influence of advanced tearing cutters on the cutting effect of cutting tools under different cutting depths, different cutting distances and different cutting speeds were studied separately, and the numerical simulation results were analyzed.The result shows that under the con-dition of constant cutting depth, with the increase of cutting speed, the cutting force of the tearing cutter remains generally stable, and the plowing area in the sandy pebble formation do not change significantly, indicating that when the tearing cutter cuts soil at low speed, the change of the cutting speed of the tearing cutter has little effect on the cutting effect of the tool.Under the condition of constant cutting speed, with the increase of the cutting depth, the cutting force of the tool and the plowing area of the formation increase when the tool is cutting in the sand and pebble formation, indicating that the cutting depth can significantly affect the excavation effect of the tool, shields adopting a cutting mode with a large penetration degree in sandy pebble formation are more conducive to improving the efficiency of shield tunneling.Considering the factors of tool wear and shield parameter control, it is recommended to set the cutting depth of the tool to 50 mm.The distance between the cutting tools of the leading tearing knife significantly affects the cutting efficiency of the tool.When the cutting depth and cutting speed of the tool remain unchanged, as the distance between the tools increases, the tangential force of the tool decreases significantly.When the distance between the tools is greater than 170 mm, the cutting force of the t earing cutter tends to be stable, and with the increase of the cutter spacing, the plowing area of the cutters gradually decrease.When the cutter spacing is greater than 160 mm, the plowing area of cutters starts to separate, and the cutting efficiency of the tool becomes worse.Therefore, when the cutters are arranged, the distance between the tearing cutters can be set between 150 mm to 160 mm.At the same time, the correctness of the numerical simulation calculation results is proved by studying the change law of the actual wear value of the tearing cutter.