By the use of finite element program MIDAS/GTS, the weak soil strata in Shenzhen metro line 5 was used to analyze the ingort which the pile groups lood had on the three - centred horseshoe shaped tunnel, and the influence of tunnel vault displacement due to the pile groups layout and the distance between piles and tunnel was also studied. The results show that the crown settlement of tunnel line reduce with the increase of pile space and distance between pile and tunnel, and the influence of the vertical pile distance is less than the parallel pile distance. The influence of the pile length is related to the burying depth of tunnel, while the crown settlement of tunnel increases with the increase of the ratio of length and burying depth of tunnel. The terminal of pile in the same depth with the tunnel should be avoided so as not to engender the maximum displacement. The crown settlement of tunnel decreases with the increase of the length of shelter pile and the distance between shelter pile and tunnel the ratio of shelter pile length and tunnel burying depth being over 1.2 may bring a better effect.%利用MIDAS/GTS有限元程序分析了深圳地区中软土地层中群桩荷载对三心圆类马蹄形隧道的影响,研究群桩布置以及桩与隧道间距的变化对隧道拱顶位移的影响情况.研究结果表明:隧道拱顶位移随桩与隧道间距以及沿隧道走向和法向桩间距的增加而减小,沿隧道走向桩间距的变化对隧道拱顶位移的影响大于沿隧道法向桩间距的变化.隧道因群桩荷载引起的位移的防护措施有:隧道拱顶位移随受荷桩桩长的增加而减小,且受荷桩桩长与隧道埋深比值应大于1,应避免受荷桩桩端处于隧道所在平面,否则将引起最大的隧道位移；采用设置隔离桩的方法减小隧道拱顶位移时,宜增加隔离桩与隧道间距,当隔离桩桩长与邻近桩桩长之比大于1.2时能起到更好的遮拦效果.
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