在浅埋地下结构物周围设置碎石排水层具有一定抗上浮效果,但该措施仍有改进的空间.为分析改进措施的抗上浮效果,采用有限单元-有限差分耦合数值方法,对比分析不采用抗浮措施、设置U型碎石排水层和改进碎石排水层措施的抗上浮效果.结果发现:改进的碎石土层方法要明显优于设置U型碎石排水层方法,但会增加地铁站的加速度响应,其抗上浮机制是通过抑制结构周围土体的超孔隙水压力累积和限制土层的流动变形引起的上浮来减小地铁站的上浮量,且其抗上浮效果因地震强度的不同而不同.%Adding gravelly soil around the shallow-buried metro station has some positive effect on decreasing the uplift of the structure,but the method still can be improved. The anti-uplift effect of tunnel structure by original design,that by U-shaped gravelly soil and that by improved gravelly soil are compared and analyzed by an element-finite difference coupling method. The results show that the anti-uplift effect of improved gravelly soil is better than that of U-shaped gravelly soil;more severe acceleration response of the structure would be induced the by improved gravelly soil;the anti-uplifting mechanism of improved gravelly soil is restraining the accumulation of excess pore water pressure of soil and restricting flow deformation of liquefied soil around the metro station to reduce the uplift displacement of the structure;the performance of uplift control varies with different earthquake density.
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