英语原文共 22 页，剩余内容已隐藏，支付完成后下载完整资料
Full 3D modelling for effects of tunnelling on existingsupport systems in the Sydney region
Abstract：
The assessment of the interaction between a new tunnel and existing structures is an important issue in urban areas. In this study, theeffect of tunnelling on the existing support system (i.e. shotcrete lining and rock bolts) of an adjacent tunnel is firstly investigated usingABAQUS and TUNNEL3D through full three-dimensional (3D) finite element calculations coupled with elasto-plastic material models,which takes into account the tunnelling procedure, the interaction between the shotcrete lining and rock mass, the interaction betweenthe rock bolts and rock mass, and the elasto-plastic behaviour of the rock mass, the shotcrete lining and the rock bolts. Then, on the basis
of the calculated results, it is concluded that the driving of the new tunnels is gnificantly affects the existing support system when the advancing tunnel face passes the existing support system and is minor when the face is far from it. Moreover, the support system inthe side of the existing tunnel closest to the new tunnel is more significantly affected than that on the side opposite to the new tunnel.It is also found that in a region such as Sydney with relatively high horizontal regional stresses, the driving of the new tunnel will notcause considerable adverse effects on the existing support system, if the new tunnel is driven horizontally parallel to the existing tunnel
with a sufficient separation, since both the tensile stress in the existing shotcrete lining in the lateral sides of the preceding tunnel and thecompressive stress at the crown decrease although noticeable tensile stress increments are observed on some parts of the existing rock bolts. Finally, it is pointed out that the effects of tunnelling on the existing support system strongly depend on the position between the original and new tunnels. In terms of the stress increments on the existing support system, especially the maximum tensile stress increments on the existing shotcrete lining, the driving of the new tunnel causes increasingly adverse effects on the existing support system in a
sequence of: (i) horizontally parallel tunnels with a separation of 30 m; (ii) horizontally parallel tunnels with a separation of 20 m; (iii) staggered tunnels with a separation of 30 m; (iv) vertically alignment tunnels; and (v) staggered tunnels with a separation of 20 m in the cases investigated in this study. For the relatively high regional stresses in the Sydney region, the obtained results qualitatively
agree with otherrsquo;s published observations from the construction of closely parallel subway tunnels.
Keywords: Interaction; Tunnelling; Shotcrete lining; Rock bolts; 3D modelling; FEM
1 Introduction
The growth of many cities has resulted in the need for increased infrastructure. As urban spaces become more limited, underground facilities such as tunnels are becoming more and more efficient in providing the required infrastructure such as mass rapid transit systems (both rail and road), sewerage, power transmission tunnels, communication and other subsurface lifelines. As a result, close positioning of tunnels, and particularly the construction of new tunnels in close proximity to existing structures such as tunnels and their support systems becomes indispensable in congested urban areas. This may be done to increase design freedoms or to make tunnel construction more economical. In such cases, it is essential to protect the adjacent tunnels as well as their existing support systems, and tocontrol the construction of the new tunnel in order not to cause adverse effects on them since the construction of the new tunnels leads inevitably to ground displacements and deformations, which may affect the adjacent tunnel and its existing support system and lead to unacceptable damage. Thus, the prediction of the effect of tunnelling on the adjacent tunnel and its existing support system becomes an important issue in the planning, designing and constructing processes of new tunnels.
Several approaches, namely, empirical methods, analytical methods and numerical methods are commonly used for the predictions of ground movements and settlements associated with tunnelling.
In engineering practices, empirical methods are generally used to predict tunnelling-induced ground movements.Peck (1969) stated that the transverse settlement trough caused by a tunnel could be described by a Gaussian error function. This mathematical description has been widely accepted (Attewell and Woodman, 1982; Orsquo;Reilly and New, 1982) since then, although it has no theoretical basis. However, as pointed out by Loganathan and Poulos(1998), empirical methods are subjected to some importation limitations in their applicability to different ground
conditions and construction techniques, and in the limited information they provide about the horizontal movements and subsurface settlements. A few attempts (Sagaseta,1987; Loganathan and Poulos, 1998; Chen et al., 1999) have been made to develop closed form analytical solutions that incorporate all of the factors that may contribute to ground deformations.
However, empirical methods and analytical methods are restricted to lsquo;free-fieldrsquo; (Chen et al., 1999) or lsquo;green-fieldrsquo;(Franzius, 2003) situations (i.e. in the absence of any structures)and can not deal with problems involving the interaction
between a tunnel and existing structures such as adjacent tunnels and their support systems. To analyse the interaction problem between a new tunnel and an existing
one, numerical methods may provide a flexible tool.
According to the review conducted by Gioda and Swoboda(1999) on numerical methods used in tunnel engineering,the finite element method (FEM) is a well-recognised numerical tool that can be used to analyse tunnellinginduce
剩余内容已隐藏，支付完成后下载完整资料
资料编号：[146449]，资料为PDF文档或Word文档，PDF文档可免费转换为Word
以上是毕业论文外文翻译，课题毕业论文、任务书、文献综述、开题报告、程序设计、图纸设计等资料可联系客服协助查找。
