复合地层中不同刃形滚刀与岩石接触行为研究

Contact Behavior of TBM Cutters with Different Profiles in Composite Stratum

目的滚刀截面形状即刃形对滚刀综合性能影响显著,研究不同刃形的滚刀在复合地层中的载荷变化特点,把握各型滚刀应用于复合地层时的优势与劣势,对于减少滚刀失效、降低刀盘偏载具有重要指导意义。方法通过滚刀破岩试验获取和对比3种刃形的滚刀(平顶、圆顶和螺旋槽滚刀)在软硬复合地层中的切削力、破岩体积等关键指标,同时建立滚刀破岩有限元数值模型,探究滚刀刃形影响其切削岩石性能的机理和规律。结果在复合地层中工作时,平顶滚刀所需的法向力均值最高,其余滚刀则相近。这是由于圆顶和螺旋槽滚刀破岩时仅有部分表面参与接触,接触面积均小于平顶滚刀,应力集中效应明显,从而降低破岩法向力。螺旋槽滚刀在切削不同强度岩石时的法向力差距最小;圆顶滚刀的法向力标准差的值最小。3种滚刀均形成了粉末状和片状岩石碎片,平顶和圆顶滚刀形成的岩石碎片总体积相近而螺旋槽滚刀略低。结论复合地层软硬岩强度相差较大时,可选用螺旋槽滚刀以减轻刀盘偏载;硬岩部分强度较高时,推荐选用圆顶滚刀,以减小切削力和载荷冲击。

Composite stratum is one of the common geological conditions in tunnel construction.When working in composite stratum,the load of cutters is changed greatly,which makes cutters or cutter head more prone to damage.The cross-section profile of cutter has a key effect on its comprehensive performance.It is of great significance to study the load variation characteristics of the cutters with different cross-section profiles,and to obtain the advantages and disadvantages of various cutters applied to composite stratum,so as to reduce the abnormal damage of cutter and the offset load of cutter head.In this work,nine groups of experiments were designed to study the performance of cutters with three cross-section profiles at three invasion depths.Through the rock cutting experiments,the cutting force and rock fragment volume of three cutters(flat-top,circular-top and spiral groove cutter)applied in the soft and hard composite stratum were obtained and compared.ANSYS and LSDYNA software were used for joint simulation to establish the finite element numerical model of rock breaking with a single cutter,elastic plastic model was used for cutter,JHC model was used for rock,and erosion contact algorithm was used to simulate the contact behavior of cutter and rock.This model was used to explore the mechanism of the effects of cutter profile on rock cutting efficiency.The results indicated that in the composite stratum,the average normal force required by flat-top cutter was the highest,and the average normal forces of other cutters were similar.This was because for the circular-top cutter and spiral groove cutter,only part of the surface was involved in contact with rock,and the contact area of these two cutters was smaller than that of flat-top cutter,so the stress concentration effect was stronger,leading to a lower normal force required to break the rock.The difference of normal force of the spiral groove cutter was the smallest in cutting rock with different strength,which indicated that the use of this type of cutter could reduce the uneven distribution of the load of the cutter head in the composite stratum.The standard deviation of normal force of circular-top cutter was the smallest,namely that the degree of load fluctuation was the lowest.Powder and rock chips were formed by all three cutters.In general,at the same single invasion depth,the difference of rock breaking performance of the three cutters is not obvious,the total volumes of rock fragments formed by flat-top and circular-top cutters are similar,while that of spiral groove cutter is slightly lower.When the strength of soft and hard rocks in the composite stratum varies greatly,the spiral grooving cutter is recommended to reduce the unbalanced load of the cutter head.When the strength of the hard rocks is high,it is recommended to use a circular-top cutter,which can effectively reduce the impact of load.