暗挖隧道施工诱发的邻近管线变形规律与控制技术

发布时间：2018-12-20 14:47

【摘要】：地铁建设在促进城市快速发展中占有重要地位,城市地下管线是保证城市正常运行的基础设施,管变形破坏会影响城市地铁隧道的施工和正常运营。因此,在地铁隧道施工过程中,确保既有管线的安全至关重要。本文以西安地铁4号线某暗挖隧道穿越既有地下管线工程为依托,采用理论分析、现场监测和数值模拟相结合的手段,对暗挖隧道穿越既有管线的地表及管线变形规律及管线变形控制措施进行研究。主要内容及结论有:(1)提出了影响既有管线变形的主要因素,研究了暗挖隧道施工诱发邻近管线变形的规律,分析了不同类型管线的变形特性。(2)采用FLAC~(3D)软件对黄土地区影响管线变形的各类因素进行了研究,并根据模拟结果得出了地层沉降槽宽度、最大沉降量与管线沉降槽宽度及沉降量之间的函数关系,计算了各种工况下的管线沉降槽曲线、管线最大转角、附加弯矩及剪力。结论指出:(1)影响西安城区场地差异的土层主要为新黄土;(2)因隧道施工工法不同而引起的管线沉降量由大到小为:上下台阶法≥正台阶预留核心土法≥短台阶+临时仰拱法≥CD法≥CRD法;(3)管材对管线变形的影响主要是因为材料刚度的不同,管线与下卧土层间会出现管土分离的情况,此时管线上方土体的压力使得管线对其产生反作用,增大管线在接口处产生剪切破坏的可能性;(4)管径越大,管线沉降越小,但其所受附加应力却越大;(5)与隧道垂直和平行的管线最大沉降值相差不大,但垂直工况管线受附加弯矩和剪力更大,更易破坏;(6)经计算可知,埋深≤2m的管线,其转角、所受弯矩和剪力均小于控制标准,在实际工程中,若埋深≤2m且无特殊状况的管线可不予考虑;(7)与隧道平行的管线,当管线距离隧道正上方水平距离≥1.5D时,管线沉降很小,若无特殊情况,则无需采取保护措施。(3)采用FLAC~(3D)软件对实际工程中地铁隧道暗挖施工诱发的既有管线的受力变形进行预测,数值模拟及理论计算结果表明:管线沉降主要集中在-1.5~1.5D的穿越过程中;实测结果与模拟及计算结果近似;在采用了短台阶+临时仰拱法进行隧道开挖后,施工引起的管线变形量满足规范要求,相关结论及控制措施可以为类似工程提供参考。
[Abstract]:Subway construction plays an important role in promoting the rapid development of the city. Urban underground pipeline is the infrastructure to ensure the normal operation of the city. Pipe deformation and failure will affect the construction and normal operation of urban subway tunnel. Therefore, it is very important to ensure the safety of existing pipelines in subway tunnel construction. Based on the underground pipeline project of a hidden tunnel in Xi'an Metro Line 4, this paper adopts the method of combining theoretical analysis, on-site monitoring and numerical simulation. The deformation law of surface and pipeline and the control measures of pipeline deformation are studied. The main contents and conclusions are as follows: (1) the main factors affecting the deformation of the existing pipeline are put forward, and the law of the deformation of the adjacent pipelines induced by the tunneling construction is studied. The deformation characteristics of different types of pipelines are analyzed. (2) various factors affecting pipeline deformation in loess area are studied by FLAC~ (3D) software, and the width of settlement trough is obtained according to the simulation results. The function relationship between the maximum settlement and the width and settlement of the channel is calculated. The curves of the channel, the maximum angle of the pipeline, the additional bending moment and the shear force are calculated. The conclusions are as follows: (1) New loess is the main soil layer that affects the site difference in Xi'an urban area; (2) the settlement amount of pipeline caused by different tunnel construction methods is as follows: upper and lower step method 鈮，

本文编号：2388147