列车振动荷载作用下管片接缝对盾构隧道衬砌结构与周围软土地层动力响应影响研究

Influence of segment joints on dynamic response of shield tunnel and surrounding soft soil due to train induced vibration

为探究盾构隧道管片接缝对于隧道结构及周围软土地层的动力响应的影响,采用模型试验与数值模拟相结合的方法,借助2种不同的盾构隧道模型——忽略接缝的均质圆环模型与考虑接缝效应的管片衬砌拼装模型,以频域分析为基础,模拟计算列车振动荷载全频域内隧道衬砌结构及周围软土地层的频率响应函数,分析在不同频率荷载作用下衬砌结构的内力分布规律。研究结果表明:在列车振动荷载作用的频域区间内,隧道结构和软土地层的竖向加速度响应均呈现出随频率升高而增强的趋势,在低频段(0~60 Hz)增长迅速,中高频段(60 Hz以上)则增速放缓;管片接缝的存在使隧道结构的动力响应明显降低,最高幅值可达10 d B,但影响范围主要集中于40~200 Hz的中高频率荷载区段;管片接缝对软土地层的动力响应也具有一定的影响,但影响程度远小于隧道结构本身;管片内力主要集中于施加振动荷载的拱底附近,接缝对管片环所受轴力有较为明显的影响,而对结构所受弯矩影响较小。从模型试验与数值模拟计算结果可以看出,考虑列车振动荷载作用下隧道衬砌结构的动力响应时,应充分注意管片接缝的影响。

This paper presents a study of the influence linings and surrounding soft soil. Both the physical tests of segment joints on the dynamic behaviours of shield and numerical simulation were conducted. Two models were used in this paper, the homogeneous ring model which ignores the segment joints and the assembled segment lining model which considers the segment joints. The vertical dynamic response of the tunnel lining and soft soil were measured and calculated according to the frequency domain analysis. The frequency response function of the model and the internal force distribution of lining structure are obtained. Results show that the vertical accelerations of the tunnel lining and soft soil increase with the excitation frequency. The response increases rapidly from 0 to 60 Hz, however, the increasing trend slows down when the excitation frequency above 60 Hz. The dynamic response of the tunnel model with joints is clearly smaller than that of the homogeneous ring model. The maximum difference is up to 10 dB. However, the influence of segment joints on the tunnel response is mainly in the frequency range of 40 - 200 Hz. The influence of the joints to the response of surrounding soft soil is clearly smaller. The intemal forces of lining structure are concentrated in the area where load is applied. The segment joints have a remarkable effect on the axial force of lining and little effect on the bending moment. According to the results, it is important to consider the effect of segment joints on the dynamic behaviour of the tunnel lining due to the train induced vibration.