地铁循环荷载下隧道下卧土体动力特性研究

随着我国城市地铁交通建设和运营里程的持续增加，列车荷载作用下隧道下卧土体的动力稳定问题备受关注。以粉质黏土地层中单线圆形地铁隧道为工程背景，采用室内模型试验和数值计算方法，分析了地铁循环荷载作用下隧道下卧土体中加速度峰值、沉降变形等的变化规律。结果表明，相较于循环荷载幅值，隧道下卧土体中加速度峰值衰减特性受循环荷载频率影响更为明显。单线圆形隧道周围约2倍直径范围为循环荷载作用影响区域，其中以0.5倍直径范围内影响最为显著。单线圆形隧道下卧土体的动力响应还受隧道埋深、隧道直径等因素影响，隧道埋深越深，隧道直径越大，下卧土体动力响应值越小，对隧道的安全有利。

Dynamic characteristics of the underlying soil of subway tunnel under cyclic loading

With the continuous increase of urban subway construction and operation mileage in China, dynamic stability of the soil around subway tunnel under cyclic load have been attracted much more attention. A single-track circular subway tunnel in silty clay layer was analyzed by using laboratory model test and numerical calculation method, the max-acceleration and settlement deformation in the underlying soil of the tunnel under cyclic load were obtained. The results show that compare with the amplitude of cyclic load, the frequency of cyclic load has a more obvious influence on the attenuation characteristics of the max-acceleration in the underlying soil. The influenced zone of a single-track circular subway tunnel is about 2 times of the tunnel diameter, in which 0.5 times of the tunnel diameter has the most significant influence. The dynamic response of the soil is also affected by the burial depth and diameter of the tunnel. The deeper burial depth and larger diameter of a tunnel have the smaller the dynamic response of the soil and benefit for the safety of the tunnel.