500kV地下变电站基坑围护结构抗震影响因素

以上海世博会500 kV地下变电站基坑围护结构为例,运用三维快速拉格朗日程序FLAC3D进行建模计算,研究了一些对基坑围护结构以及周围土体抗震稳定性有较大影响的因素:基坑周围土体性质、围护结构材料性质、地震波的峰值加速度以及地震波的卓越频率。结果表明:基坑的振动变形受周围土体的约束,土体的性质越好,约束作用越明显,振动变形越小;基坑的存在对周围土体的震动特性影响也很小。基坑围护结构的强度对基坑整体振动变形有影响,但是影响作用不明显;围护结构内力值随围护结构材料强度增大而增大,抵抗破坏的能力同样也随之增强。同一地震波若放大其峰值加速度,则使其能量放大,基坑的振动变形也随之变大,然而其内力值变化不明显。基坑在周围土体的约束下,没有表现出相应的自振特性。所得出的结论可以为类似圆形深基坑抗震设计提供参考。

Analysis on seismic influence factors of underground electric substationfoundation pit enclosure structure

Based on the 500 kV undergr ound elect ric substat ion foundation pit enclosur e st ructure ofShanghai World Expo, a mo deling calculat ion w as done with the fast larg ang ian analysis of co nt inua in dimensions(FLAC3D , and some majo r influence factor s on the foundat ion pit enclosure st ructure and the seismicstabil ity of the sur rounding soil w ere studied. T he factors included fo ur aspect s, namly the nature ofthe surrounding soil of the pit , the proper ties of the foundation pit enclosure structure, the peak acceleration o f the seismic w aves and the dominant f requency of the seismic w av e. The r esul ts show that the v ibration o f the pit deformat io n is const rained by the surro unding soil, that the better the nature of the so il , themor e obvious the const raints, and the smaller the vibration defo rmat ion, that the pit has also lit t le influenceo n the vibr at ion of the surr ounding soil, that the st rength of the underg round substat ion has an effecton the vibrat io n deformat io n o f the w hole pit , but the influence is no t obv io us, that the inter nal force v alueof the enclosur e str ucture and the ability of damag e resistance increase w ith the material st reng th of the enclosure str ucture, that if the seismic w ave amplifiee it s peak acceler at ion, it s energ y w ill amplify as w el l asthe deformat ion of the pit , but internal fo rce value has no obvious chang e, and that under the const raint ofthe surrounding soil, the pit show s no cor respo nding natural vibrat io n characterist ic. T hese co nclusionsmay pr ovide reference similar circular fo undat ion pit seismic design