复合地层下盾构施工模态系统刀盘荷载及振动特性研究

基于苏埃通道盾构工程和盾构及掘进技术国家重点实验室的盾构施工模态系统的刀盘实体,利用JHC本构模型对岩体进行仿真,通过显示动力学软件LS-DYNA对不同模式下的滚刀群切削复合地层进行数值模拟,并结合滚刀、刀盘的力学分析及傅立叶变换函数,得到滚刀和刀盘的三向荷载-时间历程曲线及荷载的频谱图。通过分析荷载曲线及频谱图可知:1)在荷载特性方面,切削过程中滚刀和刀盘荷载均具有突变性、随机性和冲击性;当滚刀运动经过软硬岩层交界面时,滚刀切点荷载发生突变,有可能发生剧烈震荡。2)在振动特性方面,刀盘荷载的频率主要集中在0~5 Hz,属于典型的低频振动,并与滚刀的频率分布一致;软岩及硬岩仅对滚刀荷载的幅值产生影响,对其频率分布影响有限。结合刀盘在软硬不均地层条件下静力学的分析结果,确定刀盘在不均匀受力状态下的最大应力、应变位置,为苏埃通道滚刀破岩物理模型试验刀盘测试系统的构建提供了依据。

Study of Vibration and Loads Characteristics of Modal  Cutterhead of Shield Boring in Composite Ground

The rock is simulated by JHC constitutive model, the rock broken by shield cutter group under different modes are numerically stimulated by dynamic analysis software LS DYNA; and then the time dependent three dimensional load and load spectrogram of disc cutter and cutterhead of shield are derived by mechanical analysis of disc cutter and cutterhead and Fourier transform, by taking Su’ai shield tunnel and cutterhead of TBM under modal system for examples. The analytical results show that: 1) The loads of disc cutter and the cutterhead show mutagenicity，randomness and impact during rock breaking; the load of disc cutter varies suddenly and the disc cutter vibrates seriously when the disc cutter cutting the interface of hard rock and soft rock. 2) The loading frequency of the cutterhead, 0-5 Hz and belongs to low frequency, coincides with that of disc cutter; the soft rock and hard rock only affect the amplitude of disc cutter load, and affect the distribution of the frequency little. Furthermore, the positions of maximum stress and strain of cutterhead under heterogeneous stress condition are determined by statics analysis of cutterhead in heterogeneous strata. The results can provide reference for cutterhead test system of physical modeling experiment of rock broken by disc cutter of Su’ai Tunnel.