复杂地质大直径盾构隧道列车振动响应分析

对于高速铁路大直径盾构隧道,研究并讨论列车振动荷载对隧道结构安全性具有重大意义。以佛莞城际铁路狮子洋隧道工程为背景,基于ANSYS有限元方法,采用列车-轨道系统确定列车荷载后,计算不同工况下高速列车振动荷载对软硬不均地层大直径盾构隧道结构的影响,选取不同计算模型对比分析往复荷载作用下隧道地基累积变形的特征。计算表明:(1)双线同时有列车荷载作用时,产生的动力响应更为显著,且与两车间隔的时间有关,当间隔时间为振动周期的倍数时,振动效应最大;(2)较之主应力,列车振动对隧道位移和加速度的影响更加明显;(3)双线列车振动发生时间的偏差会引起响应的振动时程曲线产生约等于Δt的偏移现象,且振动幅值也会偏移,结构的动力响应与地层的动力响应(位移、加速度和主应力)存在相似的变化规律;(4)随着列车运行时间的累加,隧道基底土的累积塑性变形逐渐增大,但随着时间推移后期的增长速率明显减慢;(5)针对佛莞城际铁路狮子洋隧道,近东莞侧隧道基底以砂土为主,建议采用Anand J.Puppala模型进行累积塑性沉降计算;近广州侧隧道基底以淤泥为主,建议采用DingQing Li模型进行累积塑性沉降计算。

Vibration response analysis of large diameter shield tunnel under complicated geological conditions

It is significance to study and discuss the influence of train vibration load on the structural safety of large diameter high-speed railway tunnel.Based on this Shiziyang Tunnel project as the background, By use of the finite element numerical method of ANSYS, calculate and determine the train loads by Train-track system, after the high-speed train vibration load is calculated under the different condition of soft hard uneven areas of large diameter shield tunnel structure, the influence of choosing different loading calculation model for the analysis of the tunnel foundation cumulative deformation characteristics. The calculation shows that :(1) the dynamic response is more significant when the two lines have the train load at the same time, which is related to the time interval between the two workshops. When the interval time is a multiple of the vibration period, the vibration effect is the largest.(2) compared with the principal stress, the impact of train vibration on tunnel displacement and acceleration is more obvious;(3) the deviation of the vibration generation time of two-lane trains will cause the deviation of the response vibration time-history curve, which is approximately equal to, and the vibration amplitude will also be offset. The dynamic response of the structure is similar to that of the formation(displacement, acceleration and principal stress);(4) with the accumulation of train running time, the accumulated plastic deformation of tunnel basement soil gradually increased, but the growth rate slowed down significantly with the passage of time;(5)for the lionyang tunnel of guodong and liaoyang tunnel, sandy soil is the main basement of the tunnel near dongguan. Anand J. Puppala model is recommended to calculate the accumulated plastic settlement. The foundation of the tunnel near guangzhou is dominated by silt.