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Copy of Discrete element modelling of geogrid-reinforced railway ballast

土工格栅加固铁路道碴离散元建模复制

基本信息

批准号：
EP/E048153/1
负责人：
Glenn McDowell
金额：
$ 33.28万
依托单位：
University of Nottingham
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FE048153%2F1
关键词：
Copy Discrete element modelling geogrid

项目摘要

Railway ballast degrades under traffic loading. The broken fragments fill the pores, making drainage difficult. The ballast then has to be tamped, which involves inserting vibrating tines into the ballast and squeezing it to raise the sleeper back to the appropriate level. However tamping also causes particle breakage. Eventually the ballast is spent and has to be replaced. Five percent of spent ballast ends up in landfill, at a cost of millions of pounds per year. It is therefore desirable to increase ballast life and reduce maintenance costs. In order to do this, it is essential to gain an understanding of the fundamental micro mechanics.The behaviour of ballast can be characterised by triaxial testing; a large cell funded by EPSRC is now being used at the University of Nottingham. Both monotonic tests and cyclic loading tests are used; the cyclic loading tests are used to determine the behaviour of ballast under traffic stresses. In order to understand the particle mechanics, the discrete element method can be used. In the program PFC3D, there are two entities: a ball and a wall. A ballast particle can be modelled as a single uncrushable ball, or more realistically, as an agglomerate of many small balls bonded together. The aim is to model the triaxial testing of crushable ballast to gain insight into its behaviour. Geogrids are used to limit the deformation in ballast by providing interlock. This reduces settlement and therefore maintenance costs and prolongs life of the ballast. However, the ideal geogrid / ballast geometry is not known. The discrete element method will be used here to optimise the system.The outcome will be an improved understanding of ballast behaviour under monotonic and repeated loads, and the effect of geogrids, so that improved trackbeds can be designed such that maintenance costs are significantly reduced and ballast has a prolonged life.

铁路道碴在交通负荷下会退化。破碎的碎片充满了孔隙，使排水困难。然后必须夯实道碴，这涉及将振动尖齿插入道碴中并挤压它以将轨枕提升回适当的水平。然而，静电也会导致颗粒破碎。最后，压舱物耗尽，必须更换。5%的废压舱物最终被填埋，每年的成本高达数百万英镑。因此，期望增加压载寿命并降低维护成本。为了做到这一点，必须了解基本的微观力学。道碴的行为可以通过三轴试验来表征;诺丁汉大学正在使用由EPSRC资助的大型单元。单调试验和循环加载试验都被使用;循环加载试验用于确定道碴在交通应力下的行为。为了理解颗粒力学，可以使用离散单元法。在程序PFC 3D中，有两个实体：球和墙。压载物颗粒可以被建模为单个不可压碎的球，或者更实际地，作为许多小球结合在一起的聚集体。其目的是模拟可压碎道碴的三轴试验，以深入了解其行为。土工格栅用于通过提供互锁来限制道碴的变形。这减少了沉降，并因此减少了维护成本和压载物的使用寿命。然而，理想的土工格栅/道碴几何形状是未知的。本文将采用离散单元法对系统进行优化，其结果将是加深对道碴在单调和重复荷载作用下的性能以及土工格栅的影响的理解，从而可以设计出更好的道床，从而显著降低维护成本，延长道碴的使用寿命。