巨粒混合土填料蠕变特性的大型单轴压缩试验研究

发布时间：2018-08-24 19:07

【摘要】：在我国经济繁荣发展和西部大开发战略持续深入的前提背景下,近年来在云贵川等我国西部地区投入了大批资源进行基础设施建设,其中航空运输业发展优势尤其明显,在各地一大批支线机场相继展开建设,部分机场开始扩容改建。与中原地区和东部沿海地区相比,西部地区地质条件更为复杂多变,由此在设计阶段与实际建设都产生了许多特殊的工程问题,例如地基高填方处理、高海拔建设、高地震烈度、极端气候条件施工、高边坡、地质条件复杂,工作质量高要求等问题。在西南山区机场建设中经常可见高填方边坡,其所采用填料多为就地取材的岩石爆破材料,这些填料具有岩性复杂、粒径巨大等特点。现有大量工程实际经验可知,高填方填筑体沉降变形控制和蠕变特性研究是山区高填方机场修建目前所存在的主要问题和难点。本文针对西部山区机场高填方工程建设中遇到的此类问题,将重庆万州机场填方工地土样作为研究对象,通过室内基本力学实验、理论分析、数值模拟等手段进行系统性研究,主要研究内容和成果如下:(1)通过阅读和研究大量的国内外关于土体蠕变特性的文献,总结了近年来蠕变模型和研究方法,并对各种研究方法做出了系统的介绍,给出了其适用范围和存在的问题,发现在后续研究中可能遇到的困难。(2)基于室内常规土工试验,并结合现场实测资料,对碎石土填料的基本力学性质、物理指标等进行了系统的归纳和总结。通过室内单轴压缩试验确定土样的压缩强度,压缩模量等指标,为后续的固结蠕变试验与蠕变模型研究提供了依据。(3)以砂泥岩碎石土填料为研究对象,结合高填方工后沉降变形机理与工程特点,在大口径固结仪上进行一维压缩蠕变试验研究,发现巨粒混合土具有明显的衰减蠕变特征。应力水平越高,蠕变现象越显著。选择了合理的经验公式描述了应变-时间、应力-应变的关系。此外,拟合了压实土的对数形式蠕变方程和含应力影响的幂函数蠕变模型,表征了压实土的应力与应变关系,并从微观角度解释了压实土的蠕变变形机理。(4)利用复合组件Burgers体模型对一维固结蠕变结果做了分析,并得到了模型的相关参数,并对参数的意义和变化规律做了深入的分析。通过对比理论曲线与试验曲线发现,Burgers组件组合模型拟合效果较理想。(5)利用岩土工程分析软件FLAC3D内置的Burgers体模型对土样蠕变试验进行了数值模拟分析,通过与经验公式、理论模型对比验证了模型的合理性,对以后高填方工程沉降计算有很大实用价值。
[Abstract]:Under the premise of the prosperous development of our country's economy and the development strategy of the western China, in recent years, a large number of resources have been invested in the construction of infrastructure in the west of China, such as Yungui Sichuan, especially in the air transport industry. A large number of local regional airports have started construction, some airports began to expand and rebuild. Compared with the Central Plains and the eastern coastal areas, the geological conditions in the western region are more complex and changeable. As a result, many special engineering problems have arisen in both the design stage and the actual construction, such as foundation high fill treatment and high altitude construction. Problems such as high seismic intensity, extreme climatic conditions, high slope, complex geological conditions, high working quality and so on. The high fill slope is often found in the airport construction in southwest mountainous area. The fillers are mostly rock blasting materials which are made locally. These fillers have the characteristics of complex lithology and huge particle size. A large number of practical engineering experiences show that the study of settlement deformation control and creep characteristics of high fill is the main problem and difficulty in the construction of high fill airport in mountainous area. In view of the problems encountered in the construction of high fill engineering of airport in western mountainous area, this paper takes the soil samples from the filling site of Chongqing Wanzhou Airport as the research object, and carries out systematic research by means of indoor basic mechanics experiment, theoretical analysis, numerical simulation and so on. The main research contents and results are as follows: (1) through reading and studying a large number of domestic and foreign literatures on soil creep characteristics, the creep models and research methods in recent years are summarized, and various research methods are systematically introduced. The scope of application and the existing problems are given, and the difficulties that may be encountered in the subsequent research are found. (2) based on the indoor routine geotechnical test and the field measured data, the basic mechanical properties of the gravel filler are studied. The physics index and so on have carried on the systematic induction and the summary. The compression strength and modulus of soil samples are determined by uniaxial compression test in laboratory, which provides a basis for the subsequent study of consolidation creep test and creep model. (3) taking sand and mudstone gravel fill as the research object, Combined with the mechanism of settlement and deformation after construction and engineering characteristics of high fill, one-dimensional compression creep test was carried out on a large caliber consolidation instrument. It was found that the large grained mixed soil had obvious attenuation creep characteristics. The higher the stress level, the more obvious the creep phenomenon. A reasonable empirical formula is chosen to describe the relationship between strain and time, stress and strain. In addition, the logarithmic form creep equation of compacted soil and the power function creep model with stress effect are fitted to characterize the stress-strain relationship of compacted soil. The creep deformation mechanism of compacted soil is explained from the microscopic point of view. (4) the one-dimensional consolidation creep results are analyzed by using the composite component Burgers body model, and the related parameters of the model are obtained, and the significance and variation law of the parameters are deeply analyzed. By comparing the theoretical curves with the experimental curves, it is found that the fitting effect of the combined model of Burgers component is satisfactory. (5) the creep tests of soil samples are numerically simulated and analyzed by using the Burgers model built in the geotechnical engineering analysis software FLAC3D. The comparison of theoretical models verifies the rationality of the model and has great practical value for the settlement calculation of high fill projects in the future.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU411

【参考文献】