中文摘要：

依托青岛红岛—胶南城际轨道交通工程侧穿多座桥梁的工程实例,采用有限元强度折减法,对上软下硬地层桩基近接影响下的隧道安全系数变化规律进行研究。结果表明：1）水平方向上,随水平净距增大,隧道安全系数增加,至1倍洞径后,安全系数趋于稳定;2）竖直方向上,随埋深增加,隧道安全系数表现为先增大后减小;3）桩基的存在将降低隧道安全系数,增加隧道达到最大安全系数所需的埋深。通过有无桩基对比,对不同相对位置关系下的地铁隧道近接桥梁施工影响程度进行判定：1）总体上竖向的影响范围和影响程度均大于横向;2）当隧道埋深位于桩底以上时,近接施工几乎只对隧道产生影响;3）当隧道埋深位于桩底以下时,近接施工对于隧道和桥梁桩基均有不同程度的影响,当隧道位于桩底时达到最大。通过样条函数插值补全和多重二次曲面拟合的方法,给出影响系数通用分区图,并结合数值模拟下的桩基受力变形特征,得出影响系数0.8对应的等值线为强影响区与弱影响区的分界线,影响系数1的等值线为弱影响区与无影响区的分界线。通过影响分区结论与监测数据对比,验证了研究成果的实用性。

英文摘要：

The safety factor variation laws of tunnel of Hongdao-Jiaonan Intercity Railway in Qingdao laterally crossing adjacent pile foundations of bridges in upper-soft and lower-hard strata are studied by finite element strength reduction method. The results show that： 1） In horizontal direction,the safety factor increases with the increase of horizontal clear distance; and then the safety factor becomes stable when the clear distance reaches the value of tunnel diameter. 2） In vertical direction,with the increasing of the buried depth,the safety factor increases firstly and then decreases. 3） The safety factor of the tunnel would be reduced and the buried depth of the tunnel for reaching maximum safety factor would be increased due to the existence of pile foundations. The interactions between metro tunnel and pile foundations of bridge at different relative positions are as follows： 1） Generally,the vertical interacting scope and degree is larger than the horizontal ones. 2） The tunnel would be affected only if the buried depth of the tunnel is smaller than the buried depth of the pile foundation. 3） The tunnel and the pile foundations would both be affected when the tunnel is under the pile foundation bottom; and the interaction effect reaches peak when the tunnel is right under the pile foundation bottom.The universal sectioning sketch of interacting factor,isogram 0. 8 as the boundary of strong interacting zone and weak interacting zone and isogram 1. 0 as the boundary of weak interacting zone and non-interacting zone,is given by interpolation method based on polynomial spline method,multiple quadratic surface fitting method and the stress and numerical simulation based deformation characteristics of pile foundation. Finally,the practicability of the study results are testified by comparing sectioning of interacting zones and monitoring results.