基于MatDEM的TBM滚刀破岩机理研究

Rock breaking mechanism of TBM cutter based on MatDEM

全断面隧道掘进机(TBM)以其高效、安全、环保等诸多优势被广泛地应用于隧道工程建设中,其中滚刀破岩机理是TBM设计阶段和施工阶段的核心问题。由于岩石与滚刀相互作用时会发生断裂破碎,离散元法(DEM)成为研究滚刀破岩机理的有效手段,但采用一般离散元软件构建的模型尺寸相对较小,且多简化为二维侵入问题,尺寸效应明显。采用基于离散元法的MatDEM软件构建滚刀破岩大尺寸三维模型,模拟真实滚刀破岩过程。采用团簇单元模拟刚性滚刀,实现双滚刀在不同条件下的破岩动态过程。监测破岩过程中滚刀的受力特征,计算分析不同刀间距/贯入度比(S/P)下的滚刀受力模型和比能变化。模拟结果表明,滚刀破岩时的滚刀力是一种复杂无规律的冲击荷载,其值与滚刀切割参数、岩石性质等因素有关;贯入度和刀间距的增加导致滚刀需要更大的力来破碎岩石;对于一种岩石材料,存在最优刀间距/贯入度比值,使得破岩比能最小;MatDEM软件能较好模拟滚刀的破岩过程,与室内线性切割试验相结合,有利于深入、全面地探索滚刀破岩机理。

The full-section tunnel-boring machine(TBM)is widely used in the tunnel construction due to many advantages include high efficiency,safety and environmental protection etc.The rock breaking mechanism of the TBM cutter is the essence deciding the design and construction of TBM.The rock will break when it interacts with the TBM cutter.The discrete element method(DEM)has become an effective means to study the rock breaking mechanism of the cutter.However,the dimension of the numerical model generated by most discrete element softwares is relatively small and the simplified two-dimensional models are always applied,which has an obvious size effect.The MatDEM software based on discrete element method is used to construct a large-scale 3D model of rock breaking cutter,thus simulating the real rock breaking process of the cutter.The clustering unit is used to simulate the rigid cutter,which can realize the dynamic process of rock breaking under different conditions using the double cutters.The forces of cutters during the rock breaking process can be monitored,and the force model of cutters and variation of specific energy(SE)under different cutters spacing/penetration ratio(S/P)are calculated and analyzed.The simulation results show that the cutting force is a complex and irregular impact load during the rock breaking process.It is related with the cutting parameters,rock properties etc.The increase in the penetration depth and the cutters spacing requires a much higher force to break the rock.For a specific rock,there is an optimal ratio of the spacing/penetration degree,making the minimum SE for rock breaking.The MatDEM software can better simulate the rock breaking process of the cutter,which matches well with the indoor linear cutting test,thus it is beneficial to comprehensively explore the rock breaking mechanism.