湿陷性黄土地层拓宽路基增湿破坏机制研究

发布时间：2018-05-16 22:39

本文选题：黄土地基 + 路基拓宽　；参考：《长安大学》2017年硕士论文

【摘要】：近些年来,由于我国的西部大开发及一带一路战略的实施,在深厚湿陷性黄土地区开展了许多大型的工程建设项目,地基处理的难度和深度逐渐变大,原有的设计及施工理念逐渐遭遇多方面的技术瓶颈,而在湿陷性黄土地区进行工程设计的突出难题是湿陷性评价、处治深度与剩余湿陷变形量的合理性控制等。本文以探讨新加宽路基增湿变形机理和建立新加宽路基荷载下深厚湿陷性黄土地基剩余湿陷量的控制标准为研究目标,基于土工离心模拟试验,开展了不同浸水增湿工况下,拓宽路基主要破坏模式及其支配规律研究;利用有限元数值模拟软件,研究了拓宽路基发生破坏时,人工地基的湿陷量发生程度和处理深度的关系规律。本文得出了以下主要研究结论:(1)在降雨作用下,新路基的湿化破坏是一个渐进变化的过程,首先是湿陷溶洞的出现,然后是路堤边坡出现裂缝,最终坡脚浸水湿化产生过大变形引发路面结构的破坏甚至滑坡。(2)在新路地基浸水和上部新路荷载的作用下,黄土地基发生了侧向挤出,当地基浸水湿化后,由于过大的挤出变形量,将引发地表的不均匀沉陷,进而可能会引发整个上部新路基的失稳破坏。(3)新路载荷产生的附加变形,对于老路路中,呈现出反盆形分布,即老路路中处最小,两侧新加宽路基及边坡处最大,这可能会导致新老路间产生沉降差,容易引发对原路基、路面的拉裂破坏。(4)由数值分析可知,路堤填土越高,湿陷性黄土层越厚,所采取的处理深度越大,最佳的处理深度能大幅减小路基的差异沉降;针对每一种黄土层厚度,随着处理深度的增加,基底地基承载力逐渐提高,对抵御黄土湿陷变形带来的路基沉降作用逐渐增大,从而使基底的湿陷量逐渐减小。
[Abstract]:In recent years, due to the development of western China and the implementation of Belt and Road strategy, many large engineering projects have been carried out in the deep collapsible loess area, and the difficulty and depth of foundation treatment have gradually increased. The original design and construction concept has gradually encountered various technical bottlenecks, but the outstanding problems of engineering design in collapsible loess area are the evaluation of collapsibility, the rational control of treatment depth and residual subsidence deformation, etc. In order to study the mechanism of humidification deformation of new widened subgrade and to establish the control standard of residual collapsibility of deep collapsible loess foundation under the load of new widened roadbed, based on the geotechnical centrifuge simulation test, the paper carried out different conditions of soaking and humidifying. This paper studies the main failure mode and its dominating law of widening roadbed, and studies the relationship between the degree of collapsibility and treatment depth of artificial foundation when widening roadbed is destroyed by using finite element numerical simulation software. In this paper, the following main conclusions are drawn: (1) under the action of rainfall, the wetting failure of the new roadbed is a gradual change process, the first is the appearance of the collapsing cave, and then the crack appears in the embankment slope. Finally, excessive deformation at the foot of the slope leads to the destruction of the pavement structure and even the landslide. 2) under the action of the soaking of the new road foundation and the load of the upper new road, the loess foundation is extruded laterally, when the foundation is soaked and wet, Due to the excessive extrusion deformation, the uneven subsidence of the surface will be induced, which may lead to the additional deformation caused by the new road load on the whole upper new roadbed, and it will present an inverse basin distribution for the old road. That is, the old road is the smallest in the middle, and the new widening roadbed and slope on both sides are the largest. This may lead to the settlement difference between the new and the old road, which can easily lead to the original roadbed and the road surface being cracked and destroyed.) from the numerical analysis, we can see that the higher the embankment fill is, The thicker the collapsible loess layer is, the greater the treatment depth is. The best treatment depth can greatly reduce the differential settlement of subgrade. For each kind of loess layer thickness, with the increase of treatment depth, the bearing capacity of foundation increases gradually. The subgrade settlement effect on resisting loess collapsing deformation is gradually increased, so that the base collapsibility is gradually reduced.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.1

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