In the construction process ,the stress and deformation characteristics of the main structure induced by top-down excavation method of a subway station in Beijing were studied by adopting numerical caculation .By using finite ele-ment numerical simulation ,the stress state and deformation status of the top ,middle and bottom plate and side walls in response to the construction process of the station were studied to analyze the changing process of the middle pile(or col-umn) under stress during the construction .The results showed that the stress value of the middle pile changed continu-ously with the construction of the subway station ,which was tensile stress at first and then turned into compressive stress when the pit was backfilled ;whereas the the upper part of the top plate which was adjacent to the side walls and the mid-dle pile was under tensile stress ,but the bottom part was the opposite .Besides ,the differential settlement of the middle pile and enclosing supporting structure were studied ,which proved that the maximum differential settlement of the middle pile and that between the middle pile and the sidewalls were all less than the allowable value according to the specifica-tion .In the end ,the safety of the construction of the subway station and its impact on the adjacent buildings were evalu-ated .%依托北京地铁某车站盖挖逆作法施工过程，通过有限元数值模拟研究顶板、中板、底板和侧墙的受力和变形状态随施工过程的变化规律，分析中间桩（柱）受力随施工过程的变化过程。计算表明，随施工过程进行，中柱的应力变化情况为先处于受拉状态，在上覆土回填之后又转为受压状态，而顶板上侧在靠近侧墙和中间柱附近位置处于受拉状态，下侧则相反。此外，还研究了施工过程中围护结构、中间柱差异沉降规律，表明中柱间最大差异沉降以及中间柱与侧墙最大差异沉降均小于规范允许值。最后对车站施工期间的安全性以及对周围建筑物的影响进行了评价。
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