【作者】 刘保健；

【导师】 郭增玉； 谢定义；

【作者基本信息】 西安理工大学 ， 岩土工程， 2005， 博士

【摘要】 公路路基是土体构筑物,含天然土地基和人工填土路堤两大部分。引起地基沉降的荷重来自填方土堤的重量,引起路堤沉降的荷载来自本身的自重,天然地基土可能是饱和土也可能是非饱和土,而路堤填土一般是非饱和土。不论是饱和土还是非饱和土,在一定荷载水平下的沉降都是一个随时间而发展的过程,公路路堤的施工是分层随机碾压的,因而引起路基沉降的荷重也是一个随时间而发展的过程。路基的沉降分施工期沉降、工后沉降和最终沉降,施工期沉降量与工后沉降量之和等于最终沉降量,施工期沉降量和工后沉降量是可以通过改变预压固结期人工调控的,合理的调控可达到减少工后公路腐害和早运营取得经济效益的作用。因此,路基沉降过程的计算就是解决问题的关键,而目前较为成熟的水平是可计算土体的最终沉降量,对施工期沉降量目前还没有可供实用的计算方法。 可以说土体变形量与变形过程的分析与计算一直是土力学中一个非常经典的课题,已经进行了大量的研究,也积累了丰富的经验。但由于路基工程的荷载随机分层施加且经历的过程较长,路堤及地基土体在荷载变化的同时发生了密度及与之有关的压缩模摘要量、渗透系数的不断变化、路线跨越的土类复杂多变、单位工程面积上可用于测试和计算沉降的费用相对较少、以及缺乏足够的实际计算分析经验、目前高等级公路对路面平整度的高标准要求等等,使得该问题的解决在公路行业显得尤为重要。 本文充分重视现场及室内测试试验,力图发现真实的变形发展规律,在与路基工作条件相近,且理论分析较易的一维压缩与固结条件下,重点对西部地区广泛分布的且具有浸水湿陷特性的黄土地基,较常遇到的对沉降反应强烈的软土地基,较长采用的黄土压实路堤,进行了较深入的研究。在黄土湿陷变形研究中突出增湿时间过程和增湿湿陷量算法,在饱和软土的固结研究中突出荷载与土性参数随时间的变化,在土堤沉降研究中突出非饱和土的流变特性和简单实用的算法。 论文结合实际工程,对饱和软土地基和黄土填方路堤的沉降过程进行了大量的实测,揭示了大量有关公路路堤沉降变形的规律,对其土样进行了室内试验,结合理论分析,提出了具有创新性的饱和软基在荷载与土性参数变化时沉降过程计算方法、碾压黄土路堤沉降过程计算方法、黄土地基增湿过程和增湿湿陷计算方法。所有这些计算方法都与实体工程的原刑观测资料进行了对比,证明其具有一定的可靠性和非常重要的实用性。本文还同时开发了K。一K:。渗透固结设备和测试技术,使土力学中渗透系数、压缩系数、固结系数等重要参数的测试精度得到了空前的提高。 由此,本文的特点与成果可以概括为:以公路路基为对象,以黄土、软基为条件,以大量实验为基础,以工程实用为目标,以理论分析为手段,寻找得到了儿种计算路基变形及其发展过程的可行方法,为公路建设提供了重要的科学依据,对类似条件下的计算也具有重要的参考价值,为土力学的基础研究开阔了新的思路。关键词:沉降过程,流变特性,增湿变形,入渗过程—11—更多还原

【Abstract】 Highway subgrade is soil body structure including natural earth foundation and artificial fill embankment. The weight of fill embankment causes the settlement of natural earth foundation and artificial fill embankment. The natural earth foundation may be saturated soil and unsaturated soil, but the fill embankment generally is unsaturated soil. Under certain load the settlement of saturated soil or unsaturated soil is a time-developing process. During the construction of highway embankment the soil layer is rolled at random, so that the load which causes the settlement of highway subgrade is a time-developing process. The settlement of highway subgrade includes settlement during construction period, settlement after construction and final settlement. The sum of settlement during construction period andsettlement after construction is the final settlement. The settlement during and after construction can be adjusted through varying the time of precompression consolidation, and appropriate adjustment can reduce the diseases of highway after construction and yield good economic returns. So that calculating process of settlement of subgrade becomes the key to these problems. However at the present time it is the calculating of the final settlement that is practical, and there has not been a feasible method of calculating about the settlement during construction period.It can be said that the analysis and calculating of soil body deformation and process of deformation is one of the most classical topics in soil mechanics at all times. Much research has been carried out and abundant experiences are available.However because of the incrementally loading of the subgrade construction and its long process, the variation of density relevant modulus of compressibility and coefficient of permeability of road embankment and foundation along with the changing of the load on top, the complexity and polytropism of the soil types along the highway, the relatively less funds that can be used for measuring and calculating settlement on per square meter, the absence of practical experience of calculating and analysis, the high criteria at the present time for the planeness of high class highway, the answer to this problem seems to be very important in highway industry.This paper puts importance on in situ tests and laboratory soil test, and attempts to find genuine law of deformation development. With one dimensional compression and consolidation which is similar to the working condition of roadbed and easy to be analyzed, the paper puts emphasis on inundation collapsible loess foundation widespread in the west of China, on common soft soil foundation which is intense to the settlement, on compacted loess embankment and has profound research. The calculating of moistening process and collapse settlement stand out in the research of loess’s collapse deformation, the variation of load and soil parameters along with time in the consolidation of saturated soft soil, the Theologicalcharacteristic and simple and practical calculating method of unsaturated soil in the settlement of embankment.Combined with actual project, a great deal of observations and tests are carried out about the process of settlement of saturated soft soil foundation and loess fill embankment, disclosing many laws about the settlement and deformation of highway embankment, and many laboratory soil tests of the soil sample have been done. Combined with theoretical analysis, the paper puts forward new calculating method about the process of settlement of saturated soft soil foundation with the variation of load and soil parameters, calculating method about the process of settlement of compacted loess embankment, calculating method about loess moistening process and collapse settlement of loess foundation. All these calculating methods are compared to the data of prototype measurement. It is testified that the methods have determinate reliability and important practicability. At the same time, the paper develops K0-K10 percolation consolidation equipment and measuring a更多还原