泡沫轻质土在高填涵洞中应用的实验与数值模拟研究

发布时间：2018-04-17 01:08

本文选题：高填涵洞 + 泡沫轻质土　；参考：《吉林大学》2017年硕士论文

【摘要】：随着我国基础建设的逐渐完善,高速公路的建设也不断向西北地区推进,因此,受我国西北山高沟深等复杂地形、地貌的影响,越来越多的高填方路堤逐渐涌现。涵洞作为高速公路的重要基础设施之一,其设计、建设和维护都对高速公路具有至关重要的意义,但是一直以来,大范围高填涵洞病害的产生成为影响我国西北高速公路建设质量的一道难题。许多研究人员通过计算、实验分析总结得出,高填涵洞产生病害的主要原因是由涵洞顶部和涵洞两侧土体存在沉降差所引起的附加应力导致的涵顶土应力集中。因此如何恰当的解决或减少高填涵洞涵顶和涵侧土体的沉降差,对抑制附加应力的产生,降低涵洞病害产生的概率是具有重要意义。本文通过室内实验和数值仿真计算,对一种新兴的高质量轻质材料——泡沫轻质土进行分析研究,利用其轻质性、自硬性、低弹性、低成本、易施工、无需压实,达到满足的龄期后,成自立状态等优点,进行高填涵洞减荷方案研究。主要研究内容包括:(1)结合高填涵洞病害的特征,分析病害产生的影响因素和作用机理,确定轻质材料——泡沫轻质土进行回填减荷。依据泡沫轻质土的性质决定主要在涵侧填筑泡沫轻质土,不仅可以解决涵顶土应力集中问题,还可以减小涵洞侧向土应力,解决因压实不充分所引起的各类问题。(2)通过数值仿真计算,分析填土的力学参数对涵顶和涵侧土体沉降差以及涵洞竖向土应力的影响,并运用正交实验和极差分析法确定不同土体力学参数对涵洞受力的影响程度。最终确定填土的弹性模量和泊松比是影响涵顶和涵侧土体沉降差的主要因素,并以此作为换填材料选择的主要依据。(3)根据泡沫轻质土的不同用途选取试验材料,为改善轻质土的各项性能,在传统的泡沫、水泥、粉煤灰混合料中,掺入少量矿粉。运用正交实验进行配合比设计,研究不同基础组成材料用量对轻质土的强度和力学参数的影响程度,得出最佳配合比。其中,水灰比和泡沫用量对泡沫轻质土的达到固化期龄的抗压强度和内摩擦角影响较大。(4)运用Midas对泡沫轻质土的多种回填方案进行数值仿真模拟,从涵顶和涵侧土体沉降差、涵顶竖向应力和涵侧应力三方面,对比不同回填形状和回填高度的减荷效果,总结泡沫轻质土的最佳回填方案。
[Abstract]:With the gradual improvement of our country's infrastructure construction, the construction of expressway is advancing to the northwest area. Therefore, due to the influence of complex topography and landform, more and more high-fill embankments emerge gradually.Culvert is one of the important infrastructure of freeway, its design, construction and maintenance are very important to expressway, but all the time,The occurrence of culvert disease in large scale and high filling has become a difficult problem affecting the quality of highway construction in Northwest China.Through calculation and experimental analysis, many researchers conclude that the main cause of culvert disease in high fill culvert is the stress concentration of culvert top soil caused by additional stress caused by settlement difference between the top of culvert and the soil on both sides of culvert.Therefore, how to properly solve or reduce the settlement difference between culvert top and culvert side of culvert is of great significance to restrain the generation of additional stress and reduce the probability of culvert disease.In this paper, a new kind of high quality lightweight material, foam lightweight soil, is analyzed and studied by laboratory experiments and numerical simulation. It is easy to construct and does not need compaction by using its lightweight, self-hardness, low elasticity, low cost, easy construction and no compaction.After reaching the satisfied age, the project of high fill culvert load reduction is studied.The main research contents include: (1) combined with the characteristics of culvert disease in high filling, the influencing factors and mechanism of the disease are analyzed, and the backfill and load reduction of lightweight material-foam lightweight soil is determined.According to the properties of foamed lightweight soil, foam lightweight soil is mainly filled on the culvert side, which can not only solve the stress concentration problem of culvert top soil, but also reduce the lateral soil stress of culvert.To solve all kinds of problems caused by insufficient compaction. (2) through numerical simulation, the influence of mechanical parameters of fill on settlement difference of culvert top and culvert and vertical soil stress of culvert is analyzed.Orthogonal test and range analysis were used to determine the influence of different soil mechanical parameters on culvert stress.Finally, the elastic modulus and Poisson's ratio of fill are the main factors that affect the settlement difference of culvert top and culvert soil, and this is used as the main basis for the selection of filling material.) according to the different uses of foamed lightweight soil, the test materials are selected.In order to improve the properties of lightweight soil, a small amount of mineral powder is mixed in traditional foams, cement and fly ash mixtures.The orthogonal design was used to study the influence of the content of different basic materials on the strength and mechanical parameters of light soil. The optimum mixture ratio was obtained.Among them, water cement ratio and foam content have great influence on compressive strength and internal friction angle of foamed lightweight soil at the age of curing period. (4) numerical simulation of various backfill schemes of foamed lightweight soil is carried out by using Midas, and the settlement difference between culvert top and culvert side soil is obtained.In this paper, the vertical stress of culvert top and lateral stress of culvert are compared, and the optimum backfill scheme of foamed lightweight soil is summarized by comparing the load reduction effect of different backfill shapes and backfill heights.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U449

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