Numerical analysis of the cutting process of shield tunneling in Beijing sandy pebble formation

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.