【作者】 严涛；

【导师】 金学松；

【作者基本信息】 西南交通大学 ， 载运工具运用工程， 2010， 硕士

【摘要】 国内外越来越多的大中型城市已经建成或正在建设城市地铁,人们越来越关注地铁隧道开挖所造成的地表沉降和地铁列车运行所引起的环境振动。本文运用有限元软件ANSYS并结合深圳地铁2号线沙-世区间,分别从不同断面开挖半径、不同开挖进尺、不同隧道埋深、不同开挖方法、有无超前支护等方面去研究了地表沉降规律。结果显示：开挖半径越大,开挖循环进尺越长,地表沉降越大；地表沉降与隧道埋深成反比,隧道埋深越深,地表沉降越小,隧道埋深越浅,地表沉降越大；弧形台阶法控制地表沉降最佳,上下台阶次之,全断面开挖引起的地表沉降是这三种开挖方法里最大的；施作超前支护能较好的控制地表沉降。以上计算结果为地铁隧道开挖方案优化提供了依据。分别选择深圳地铁2号线沙-世区间Ⅳ级、Ⅴ级、Ⅵ级典型断面作为研究的目标断面,通过对比数值计算以及现场实测所得的地表沉降值看出,两者变化趋势总体一致,说明数值计算结果是可信的。但是数值计算值相比现场实测值偏小,通过数值计算指导施工时应该考虑乘以一定的安全系数,以使计算值更加符合现场实测值。隧道埋深、地铁列车运行速度、荷载频率、隧道衬砌弹性模量等因素对地面振动有极大的影响。隧道埋深越深,地面振动越弱；速度越快,地面振动越强；计算表明,低频对地面的振动影响更为持久,高频衰减较快；在满足结构安全受力的前提下,减小衬砌混凝土弹性模量,可以减小地面振动。更多还原

【Abstract】 As more and more cities begin to build subway, there is growing concern about surface subsidence caused by subway tunnel excavation and environmental vibration caused by subway train operation. This paper uses the finite element software ANSYS to analyze the factors influencing on the surface settlement in Sha-Shi section construction of Shenzhen Metro Line 2. These factors are, respectively, the excavation radii of different sections, different excavation footages, different tunnel depthes, and excavation methods with or without the advance support. The obtained results show that:the larger the excavation radius, the longer the excavation footage cycle and the greater the surface settlement; the urface subsidence is inversely proportional to tunnel depth, namely the surface subsidence is smaller if the tunnel depth is deeper. The Arc Shape Step Method for tunnel excavation is the best way to control the subsidence, while, successively for The Up and Down Step Method and for The Full Face Excavation Method. The onstruction method with the advance support is also a better way to control the surface subsidence. The conclusions above are available for optimization of the subway tunnel excavation. The typical sections of gradesⅣ,ⅤandⅥof in Sha-Shi section are selected in the analysis. By comparing the ground surface settlement obtained by numerical calculation with the field measurement, it can be seen that their overall trend are very close, which indicate that the numerical results are credible. But the numerical values are smaller than the measured values, so some safety factors should be used to multiply the critical numerical value to guide the tunnel construction for safety. Tunnel depth, subway train speed, loading frequency, tunnel lining elastic modulus and other factors have great impact on the ground vibration. The deeper the depth is, the weaker the ground vibration is; the faster the speed is, the stronger the ground vibration will be. The calculation shows that the low frequency loading effect on the ground-bourn vibration is more durable and the high-frequency vibration attenuates faster. Under the premise of satisfied structural safety, reducing the elastic modulus of the concrete lining decreases the ground vibration caused by subway train operation.更多还原