地铁在地铁站附近的加减速运动会对地基土产生一定的影响.土体经过倾斜削样后使用动三轴进行不排水动力测试以研究地铁进出站作用下进出站距离、加速度、动应力幅值及固结围压对饱和软黏土累积塑性变形的影响.结果表明:进出站变频荷载循环作用下软黏土累积塑性应变曲线可大致划分为爆发增长-较快增长-逐渐稳定3个阶段.距地铁站越近、动应力幅值越大、固结围压越小,土体进入逐渐稳定阶段所需的进出站次数越少,土体竖向变形越大,剪切变形越小.进出站加速度值越大,土体竖向变形越小、剪切变形越大.对于实际工程而言,地铁运营初期,进站区间土体的沉降变形、出站区间土体水平位移、较大加速度工况下的水平位移、较小加速度工况下的沉降、高动应力幅值的工况及低固结应力的土体区域是工程地质灾害防治的重点.

The acceleration and deceleration movement of the metro near the metro station have a certain impact on the foundation soil. After the soil has been sloped and sampled, a dynamic three-axis undrained dynamic test is conducted to study the influence of the distance of the metro station, acceleration, dynamic stress amplitude, and consolidation confining pressure on the cumulative plastic deformation of saturated soft clay. The results show that the cumulative plastic strain curve of soft clay at variable frequency cyclic loading in and out of the station can be roughly divided into three stages: explosive growth, rapid growth, and gradual stability. The increase in the distance from the metro station, the increase in the amplitude of the dynamic stress, and the decrease in the consolidation confining pressure can reduce the number of entry and exit times required for the soil to enter the gradual stabilization phase, increase the vertical deformation of the soil, and reduce the shear deformation. As the acceleration value in and out of the station increases, the vertical deformation of the soil decreases but the shear deformation increases. For the actual project, the initial stage of metro operation, the settlement deformation of the soil in the inbound section, the horizontal displacement of the soil in the outbound section, the horizontal displacement under the larger acceleration condition, the settlement under the smaller acceleration condition, the high dynamic stress amplitude, and the soil area with a low consolidation stress are the focus of engineering geological disaster prevention.