摘 要

在我国综合国力的不断增强，经济的迅猛发展以及城市化进程加快的大时代背景下，城市对交通和电力的需求也日益增长。在城市高密度负荷的城区，日益拥堵的地面交通系统已经很难满足人们日常的出行要求，且传统的架空线路走廊电力输送方式受到土地资源，城市空间，市政规划，消防安全，景观等诸多因素的限制，导致其在城市电力网络建设中难以继续被采用。地下隧道则能有效地解决这些问题。地下轨道交通以其迅捷、载客量大、安全舒适、效率高、污染轻等特有优势，可以极大地缓解城市地表交通拥堵和环境污染问题；利用地下电缆隧道进行输电，不仅可以节约日益紧张的土地资源，安全有效，还可以美化城市景观，与城市建设协调发展。盾构法施工作为当下最主流的施工方法常被应用于地下轨道交通和地下电缆隧道的施工当中，在盾构机往前掘进时，往往会碰到城市中建筑物密集区以及别的地下基础设施和隐蔽工程，通常需要半径较小的曲线隧道绕过这些障碍物。在掘进小转弯半径盾构隧道时，盾尾千斤顶的顶推力会使曲线外部的土体受到挤压，同时由于盾尾间隙，会使土体向盾构隧道内侧偏移；盾构机前进的原理是依靠盾尾千斤顶对地层施加推力而获得的反力前进的，因此在曲线段盾构机往前推动时，垂直于盾构隧道方向的侧向力将会产生，使隧道向曲线外侧偏移。若隧道的纵向刚度和土层的刚度过小，这可能导致管片和外侧地层发生过大的位移。因而在现场施工时对小转弯半径隧道的轴线的把控难度极大。另外，相较于直线段盾构隧道，小转弯半径盾构隧道施工时会对周围环境引起更大的扰动，譬如地表的变形沉降和土的物理学参数：土内应力、弹性模量、孔隙水压力等等。本文采用MIDAS/GTS三维有限元分析软件对小转弯半径盾构隧道的应力变化以及地面沉降等规律进行模拟分析，为实际工程中小转弯半径盾构的设计和施工给予借鉴。

关键词：盾构法施工；小转弯半径盾构隧道；施工变形与应力变化；地层沉降

Simulation study on Small turn radius shield tunnel

ABSTRACT

In the context of China's growing overall national strength, rapid economic development and accelerated urbanization, the city's demand for transportation and electricity is also increasing. In urban area, urban high density load increasingly congested ground transportation system has been difficult to satisfy people’s requirement , and traditional way of overhead line corridor electricity by land resources, urban space, urban planning, fire safety, urban landscape, and many other factors, led to its also hard to hard to continue to use in the urban power grid construction. Underground tunnels can resolve these problems effectively. Underground rail transit has the advantages of convenience, large volume, high safety, high efficiency and small pollution, which can ease the traffic congestion and reduce environmental pollution. The use of underground cable tunnel to transport power can save land resources, safety and efficiency, and beautify the urban landscape and coordinate development with urban construction. Underground rail transit tunnels and underground cable tunnel construction by shield method commonly, shield tunneling process, in the encounter when building concentration areas and other underground facilities in a city, usually requires small radius of curvature of curve tunnel around these obstacles. During the construction of the small turning radius tunnel in the shield machine, the anti-thrust of the shield machine compresses the outer layer of the curve, while the presence of the gap of the shield will cause the stratum to shift to the inside of the tunnel. At the same time, the shield advance forward by segment and ground reaction force, so the curve segment of shield advance will produce horizontal forces in vertical direction of the tunnel, the tunnel to the curve of the lateral displacement, when the longitudinal stiffness of the tunnel and formation for small, may cause the segment and the lateral strata displacement is too large. So small turning radius curve section of tunnel axis control is difficult, at the same time segment to the lateral distortion formation as a result of extrusion formation and segments are affected by complex stress, shield machine and segment of the deviation is too large. In addition, small turning radius of shield tunnel construction, compared with the straight line segment of shield tunnel, can produce greater disturbance on the surrounding environment, such as surface subsidence, as well as soil physics parameters: stress, elastic modulus, soil moisture content and pore water pressure, etc. This article is based on the three-dimensional finite element analysis software MIDAS/GTS for small turning radius of shield tunnel construction in the process of analysis to simulate the stress variation and ground settlement law research, for the small turning radius of shield in the practical engineering design and construction to provide the reference.

Key words: Small turn radius shield tunnel; Shield construction; Construction deformation and stress change; Land subsidence

目 录

第一章 绪论..................................................................1

1.1本课题的提出..............................................................1

1.2研究的意义................................................................2

1.3本课题国内外研究现状......................................................2

1.3.1国内研究现状..........................................................2

1.3.2国外研究现状..........................................................3

1.4本课题的主要研究内容及方法...............................................10

1.4.1研究的主要内容.......................................................10