黄土与地铁车站动力相互作用模型的水平位移及沉降分析

Horizontal displacement and settlement analysis for loesssubway station dynamic interaction model

在黄土场地条件下进行土与地铁地下结构动力相互作用振动台试验。基于实测数据对黄土与地铁车站接触动土压力、模型地基竖向沉降及水平位移进行分析,对试验中模型地基地震破坏特点进行描述。结果表明:结构侧面顶部动土压力大于中部和下部,随输入峰值加速度的增大结构侧面土压力均增大;地震动较大时,地基层间剪切位移呈现顶部最大,底部次之,中部最小;地表沉降随输入峰值加速度的增加而增大,西安人工波作用下地表沉降大于松潘波和Taft波作用下沉降;结构上方地表沉降始终小于周围土层,表明结构发生相对上升运动;分析发现,结构顶、底动土压力差提供结构上升运动的内在动力。回归分析表明,地基水平相对位移与土层深度可用三次多项式拟合,两者之间具有较好的相关性。

A series of shaking table tests were performed for a loess-subway station dynamic interaction model. The dynamic soil pressure between loess and subway station,the horizontal displacement and vertical settlement of the model foundation were analysed,the seismic damage features of the model foundation were described after the tests. The results showed that the dynamic soil pressure of the structure＇s side face increases with increase in input PGA,it is higher at the side top than that at the side middle and bottom; under higher PGA foundation motion,the shear displacement between soil layers is larger at the foundation top than that at the bottom,while the shear displacement at the foundation middle is smallest; the settlement of the ground surface increases with increase in input PGA,and the peak value of settlement is larger under Xi＇an artificial wave than that under Songpan wave and Taft one; the settlement above the subway station is always smaller than that surrounding soils,the subway station uplifts relatively; the difference between dynamic soil pressures at the top and bottom of the subway station provides an uplifting force; meanwhile,after using the nonlinear regression analysis method,the relationship between the relative horizontal displacement of the ground and soil depth can be well fitted with a cubic polynomial.