中文摘要：

以广州地铁三号线大塘—沥滘区间盾构隧道穿越的地层条件为背景,针对盾构隧道结构的特点,引入横向和纵向不等的刚度折减系数,采用室内相似模型试验和三维有限元数值计算相结合的手段,对地铁盾构隧道重叠下穿施工所引起的上方已建隧道纵向变位、纵向附加轴力和弯矩、横向变形、横向附加轴力和弯矩进行了深入研究,探讨和揭示了围岩条件、隧道净距、顶推力等因素作用下盾构隧道重叠下穿施工所引起的已建隧道的变形和附加内力分布变化的影响规律。研究结果表明,新建盾构隧道施工所引起的已建隧道最大隆起点位于掌子面前方约2D（2倍直径）附近,不均匀沉降主要出现在约掌子面前方3D到后方2D的范围内,顶推施工将引起已建隧道在掌子面前方产生较大附加内力,而对后方影响较小,具体视隧道埋深、间距、围岩和施工因素而定。

英文摘要：

Considering the stratums traversed by the Da Tang—Li Jiao shield tunnel of Guangzhou metro line 3 and shield tunnel structure,similitude model test and 3-D FEM analysis with circumferential and longitudinal equivalent structural stiffness coefficients are conducted to study the longitudinal displacement,axial force and moment,the circumferential deformation,axial force and moment of an existing tunnel induced by shield tunnel construction directly underneath.Distribution of the induced deformation and force of existing tunnel,as influenced by factors such as conditions of surrounding soil,net distance between the two tunnels and advance thrust of shield machine,are discussed.The results indicate that maximum heaving of the existing tunnel occurs about 2D（two times the diameter of the new tunnel）in front of the excavation face of the new tunnel,that uneven settlement mainly occurs in the range between 3D in front of and 2D behind the excavation face,and that shield driving would cause significant additional internal force in the existing tunnel and little influence behind.