盾构切刀切削软岩特性研究

Cutting Performance of Shield Cutters in Soft Rock

文章在对盾构切刀切削软岩动态过程进行合理简化的基础上,从软岩细观角度出发,采用颗粒离散元法建立了切刀切削软岩的二维数值模型,对切刀切削动态过程进行了分析,并研究了切刀前角、切深以及节理对切刀切削特性的影响。研究结果表明:切刀切削软岩是一个先挤压后张拉的过程,切刀着力点随切削行程的改变由刀尖逐渐向刀前刃上方转移,然后再回到刀尖,与切削力变化规律一致;破碎块随切刀前角和切深的增加呈增大趋势;比能耗随切刀前角和切深的增加呈减小趋势;节理倾角不同切刀破岩呈不同破坏方式,节理倾角小于90°时,更容易形成破碎块,破岩效率较高;节理倾角大于或等于90°时,不能很好利用节理促使破碎块的形成,破岩效率较低。通过试验验证了破碎块以及切刀受力过程与数值模拟具有较好的一致性。

Based on the rational simplification of the cutting process of shield cutters in soft rock, this paper establishes a 2D numerical model using the particle discrete element method; analyzes a dynamic cutting process; and studies the influence of the rake angle, cutting depth and rock joint on the rock-breaking performance of shield cutters. The results show that cutting the soft rock is a process of ＂extruding and then tensioning.＂ The force application point of a cutter is gradually shifted from the tip of the cutter to the front edge of the cutter, and then back to the tip of the cutter with variations of the cutting stroke, which is consistent with the change of the cutter force. With the increase of the cutter＇s rake angle and cutting depth, the broken rock block increases while the specific energy consumption decreases. The rock-breaking modes of the cutter are different under different joint dip angles, and because of more easily forming the broken rock block the rock-breaking efficiency is higher under a joint angle of less than 90° than a joint angle of more than or equal to 90%. The experiments show that the actual process of rock breaking and the force applied on the cutter agree well with those determined via numerical simulation.