Continuous velocity fields for collapse and blowout of a pressurized tunnel face in purely cohesive soil
Continuous velocity fields for collapse and blowout of a pressurized tunnel face in purely cohesive soil
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DOI：
10.1002/nag.2121
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发表时间：
2013-09-01
影响因子：
4
通讯作者：
Soubra, Abdul-Hamid
中科院分区：
文献类型：
--
作者：
Mollon, Guilhem;Dias, Daniel;Soubra, Abdul-Hamid
压力盾构法隧道开挖面稳定性分析是真实的隧道工程中的一个重要问题。大多数用于纯粘性土中隧道稳定性分析的破坏机制都来自于为摩擦土开发的刚性块体破坏机制，通过施加零摩擦角。对于纯粘性土，这种机制与实际速度场相差甚远。本文提出了两种新的连续速度场，分别用于隧道工作面的坍塌和井喷。这些速度场与不排水粘土中观察到的实际破坏更加一致。它们基于正态条件，即纯粘性土中的任何塑性变形在没有任何体积变化的情况下发展。数值计算结果表明，建议的速度场显着提高现有的最佳界限的崩溃压力，他们的结果比较合理，以及商业有限差分软件提供的崩溃和井喷压力，为一个小得多的计算成本。为岩土工程的实际应用提供了设计图表。版权所有（c）2012约翰威利父子有限公司
Face stability analysis of tunnels excavated under pressurized shields is a major issue in real tunnelling projects. Most of the failure mechanisms used for the stability analysis of tunnels in purely cohesive soils were derived from rigid block failure mechanisms that were developed for frictional soils, by imposing a null friction angle. For a purely cohesive soil, this kind of mechanism is quite far from the actual velocity field. This paper aims at proposing two new continuous velocity fields for both collapse and blowout of an air-pressurized tunnel face. These velocity fields are much more consistent with the actual failures observed in undrained clays. They are based on the normality condition, which states that any plastic deformation in a purely cohesive soil develops without any volume change. The numerical results have shown that the proposed velocity fields significantly improve the best existing bounds for collapse pressures and that their results compare reasonably well with the collapse and blowout pressures provided by a commercial finite difference software, for a much smaller computational cost. A design chart is provided for practical use in geotechnical engineering. Copyright (c) 2012 John Wiley & Sons, Ltd.