基于Kӧtter方程的盾构掘进面上被切削土体受力研究

为了计算不同土体性质与不同掘进参数下盾构刮刀与土体之间的作用力以及由此带来的切削扭矩,引入了修正后的Kӧtter方程作为补充方程,求解出开挖面上土体在被动切削至破坏时滑动面上的应力分布,建立了被切削土体受力模型,求解出刮刀刃面与土体之间的正压力p、摩擦力Q与侧向土体间抗剪阻力U,进而推导出刀盘切削扭矩T的计算公式。分析得到特定刀盘上刮刀的p,Q,U值随土体c,φ值增大而增大,通过适当提高刮刀刃面粗糙度来增大摩擦可使土体更易被切至破坏;p,Q,U值随刀盘转速ω增大而减小,p,Q随支护荷载p线性增大且p对于被切削土体受力的影响在砂性土中较大,最终给出特定刀盘掘进至部分种类土体中的切削扭矩值作为工程参考。

Force states of soils under shield cutting in excavation face based on Kӧtter equation

To calculate the forces between shield scraper and soils as well as the cutting torque caused by them with different tunneling parameters in different soils, a modified Kӧtter equation is introduced as a supplement to solve the stress distribution on the sliding face when the soils in excavation face are being passively cut to a damage state. A mechanical model for cutting soils is established, and the pressure and friction between the soils and the surface of shield scraper and the lateral shear resistance are solved. Then the method for calculating the cutting torque of cutter head is derived. It can be acquired that the pressure, friction and lateral shear resistance increase with the cohesive force and internal friction angle and decrease with the rotation rate, which illustrates that a properly coarser scraper surface makes the soils easier to be cut, and a lower rotation rate can reduce the force of the tools. The pressure and friction increase linearly with the shield support pressure, which is more obvious in sand. Some cutting torques in different soil types are given as engineering references ultimately.