上软下硬地层盾构机滚刀磨损特性研究

以广州地铁某盾构区间为工程背景,结合上软下硬地层的强度特性,提出了硬地层所占面积与掌子面面积之比来评估上软下硬地层中地层分布情况的方法,确定硬地层对开挖面强度特性的影响。根据地层特性和分布情况,提出了适应不同均一地层的刀盘合理转速以及适用于上软下硬地层的刀盘设计转速。通过监测盾构机掘进过程中的刀盘扭矩变化,提出根据刀盘扭矩变化幅度制定刀盘转速调整时机的预警机制,实现刀盘转速提前调整。结合实际应用效果,上软下硬地层会使盾构滚刀产生过快磨损,超前调整刀盘转速可有效降低滚刀受冲击荷载的影响,延长滚刀正常工作时的掘进距离,显著提高上软下硬地层中盾构施工效率。

Characteristics of Disc Cutter Failures in Mixed-face Ground Condition

Based on a section tunnel of metro line in Guangzhou city, this study considered strata condition of mixed-face ground, then proposed a new method to describe the characteristics of stratum distribution by calculating the ratio of hard stratum in the cutting face. This study also proposed a design speed of cutter for mixed-face ground according to the physical properties of mixed-face ground and the reasonable speed of cutter in different uniform strata. Rotation speed of cutterhead can be changed according to the monitored torque of cutterhead during shield tunnelling. According to the field results, the mixed-face ground can lead to the excessive cutter wear. The pre-adjustment of rotation speed can mitigate the impact loading and improve the construction efficiency of shield machine.