土压平衡盾构刀盘扭矩计算模型

Calculation model of cutterhead torque for earth pressure balance shield

针对目前刀盘扭矩计算模型不统一、考虑施工动态参数欠缺的问题,提出一种考虑刀具贯入度、土仓压力的刀盘扭矩计算模型.通过现场试验及理论计算结果的对比,分析刀盘摩擦扭矩的组成,在此基础上,提出土压平衡盾构在掘进过程中刀盘扭矩不断变化的关键因素,选取3处712组现场实测数据进行回归分析,探讨刀具贯入度、土仓压力2个因素对刀盘扭矩的影响,并应用力学推导、数值模拟方法对2个因素影响刀盘扭矩的机理进行解释,给出考虑施工需求的刀盘极限扭矩的计算公式.结果表明:刀盘背面摩擦扭矩不能忽略;当刀盘贯入度增大时,刀盘扭矩明显增大的原因主要是刀盘对开挖面土体挤压的增大,而不是刀具切削扭矩的增加;土仓压力对刀盘扭矩的影响主要是增大了刀盘背面摩擦扭矩.

Aiming at the problem that the calculation model of cutterhead torque is not uniform and the dy- namic construction parameters have not been considered, a cutterhead torque calculation model considering tool penetration and earth pressure was proposed. By comparing the results of the field test and theoretical calculation, the composition of friction torque was discussed, then key influencing factors of cutterhead torque in shield tunneling process were put forword. Through the regressive analysis of 712 sets of data, the effects of cutter penetration and earth pressure on cutterhead torque were discussed. The mechanics calculation and numerical simulation method were applied to explain the influence mechanism of the two factors on cutterhead torque, and the calculation formula of cutterhead ultimate torque which considered the construction needs were given. Results show that, the friction torque of the back of cutterhead cannot be ignored; when the penetration of cutterhead increases, the main reason causing the obvious increase of cutterhead torque is the increase of extrusion of soil at the excavation face from cutterhead; and the main influence of earth pressure on cuttertorque is the increase of friction torque at the back of cutter head.