摘要
桩基施工有可能导致临近大直径盾构隧道结构变形和渗漏水等运营风险。借助平面有限元程序,建立桩基对大直径盾构影响的数值模型,通过实测数据和数值计算对比得到了指导意义的结论。成桩过程中临近隧道产生相对少量的位移。隧道向下和向桩基方向发生变位。当桩基受荷后,隧道位移量明显加大,隧道向下和向远离桩基方向发生变位。桩基成孔过程引发的土层损失,是前期地层变位的主要原因。合理提高泥浆配比,甚至在成孔时采用全程钢护筒,可以有效减少土层损失,降低隧道变形的风险。桩基受荷后,桩周形成一定范围内的剪切带。剪切效应引发结构与土的共同作用,进而使地层和结构产生应力应变响应。当桩基与隧道间距在2倍隧道结构外径以上时,隧道沉降和侧移可得到有效控制。桩基长期荷载作用下地层仍然会产生蠕变位移,对隧道结构依然存在一定的影响。
The construction of pile foundation possibly leads to the operation risks of the structural deformation and water leakage closing to the large-diameter shield tunnel. With the help of the plane finite element program, the numerical model of pile foundation influence on large-diameter shield is established. The guiding significant conclusion is achieved through the comparison of measured data and numerical calculation. The adjacent tunnel will produce relatively small displacement during the process of pile completion. The tunnel descends and changes to the pile direction. When the pile foundation is loaded, the tunnel displacement is obviously increased, and the tunnel descends and moves away from the pile direction. The soil loss caused in the process of pile foundation completion is the main reason of early stratigraphic displacement. The reasonable increment of slurry proportion and even in the pore-forming process the use of full steel casing can effectively decrease the soil loss and reduce the risk of tunnel deformation. After the pile foundation is loaded, the shear zone within a certain range is formed around the pile. The shear effect causes the interaction of structure and soil so as to make the stratum and structure produce the stress-strain response. When the spacing of pile foundation and tunnel is more than 2 times of the outer diameter of tunnel structure, the tunnel settlement and sidesway can be effectively controlled. The stratum will still have creep displacement under the long-time load action of pile foundation. There are still some influences on the tunnel structure.
出处
《城市道桥与防洪》
2018年第6期288-291,共4页
Urban Roads Bridges & Flood Control
关键词
桩基
大直径盾构隧道
相互作用
影响分析
pile foundation
large-diameter shield tunnel
interaction
influence analysis
