TBM滚刀破岩动态特性与最优刀间距研究

在对实际工况合理简化的基础上，从岩土细观角度出发，采用颗粒离散元法建立滚刀侵入岩体的二维模拟模型，研究双滚刀作用下岩体的动态响应机制，找出滚刀侵入过程中岩体裂纹、贯入度以及切削力三者的关系。在此基础上，通过数值模拟对常见切深下滚刀最优刀间距问题进行分析，得到不同切深下比能耗与刀间距的规律，并通过试验对双滚刀破岩过程中岩体动态特性以及最优刀间距问题进行验证，最后以工程实例验证研究结论。研究表明：仿真过程中，切削力随贯入度的变化与岩体的跃进破碎特性相一致，岩体破坏服从格里菲斯理论；较小切深下岩体为剪切破坏，较大切深下岩体发生拉应力破坏；切深为10 mm时比能耗有明显拐点，此时刀间距为100 mm；切深为6 mm时，60 mm刀间距下比能耗最小；切深小于2 mm时，实际工况下岩体不能产生贯穿裂纹。

RESEARCH ON ROCK DYNAMIC FRAGMENTATION CHARACTERISTICS BY TBM CUTTERS AND CUTTER SPACING OPTIMIZATION

On the basis of reasonably simplified practical tunneling conditions，from meso-level structure of rock mass，the 2D model of rock chipping process induced by tunnel boring machine(TBM) disc cutters was established using particle discrete element method. The dynamic response mechanism of rock fragmentation induced by two cutters was studied；and the relationships of cracks，penetration and cutting force of rock mass were obtained. The optimum cutter spacing under common cutting depths was simulated，from which the relationship between cutter spacing and specific energy consumption under different cutting depths was analyzed. Then，the corresponding experiments were carried out to verify the rock dynamic fragmentation characteristics and optimum cutter spacing. Finally，the field TBM performance was taken to corroborate the conclusion. The results show that：(1) The change of cutting force with penetration is in good consistence with the jump crashing of rock；and the failure of rock follows the Griffith theory. (2) The breakage of rock mass is shear failure under small cutting depth，while the breakage of rock is caused by tensile stress under large cutting depth. When the cutting depth equals to 10 mm，the specific energy has obvious inflection point at the cutter spacing of 100 mm. The specific energy is achieved minimum at the cutter spacing of 60 mm when the cutting depth equals to 6 mm. The crack can?t penetrate rock when the cutting depth is less than 2 mm.