交叉隧道施工中新建隧道周围复合地层与间距对既有隧道的沉降影响研究
INFLUENCE OF MIX GROUND AND SPACE AROUND NEW TUNNEL ON EXISTING TUNNEL SETTLEMENT DURING CROSSING SHIELD CONSTRUCTION
-
摘要: 沿海地区特别是广州地区地铁建设多在复合地层中进行盾构施工,开挖引起的地层沉降很难控制,如何防止大面积的地层沉降,保证既有建(构)物安全成为施工难题。基于此,本文提出了复合地层盾构施工的地质概化模型,运用三维有限元方法对交叉隧道盾构施工进行了建模分析,研究了不同的复合地层类型及不同的覆土厚度与间距下,新建隧道盾构正交下穿施工对既有隧道沉降的影响。结果表明,新建隧道在近似均一土层中下穿施工引起的既有隧道沉降最大,上软下硬地层次之,长距离硬岩段最小,沉降随土层弹性模量的增加而减小; 同时,既有隧道沉降随覆土厚度的增加而增大; 随隧道间距的增大而减小,当间距小于2倍衬砌外径时,既有隧道沉降较大,存在损坏的危险。最后,提出了相应的沉降控制对策。Abstract: A majority of the metro constructions in coastal area especially Guangzhou region are built in multi-strata ground. For this propose,a simplified geological model is proposed.With 3D-FEM,the influence of under-crossing construction on the displacement of the existing tunnel under different types of multi-strata ground,the thickness of the overlay soil and the distance of two tunnels is studied.The results show that when the new tunnel building in the homogeneous ground,the displacement is the maximum.The displacement for the case of upper-soft and lower-hard ground takes the second place.The displacement for the case of hard stratum is the minimum.The displacement of the existing tunnel decreases as the soil parameters increase.The displacement of the existing tunnel increases as the thickness of overlay soil increases and decreases as the net distance of two tunnels increases.When the net distance is less than 2 times of lining diameter,the displacement of the existing tunnel is great and the existing tunnel has risk of damage.Finally,corresponding measures are suggested to control the settlement effectively.
下载:
