基于正交设计土石混填体大型三轴试验研究

发布时间：2018-06-07 20:52

本文选题：土石混填体 + 正交试验设计　；参考：《湖南大学》2015年硕士论文

【摘要】：随着南方山区的基础建设的快速发展,在路基工程建设中,越来越多的使用山体开挖而成的土石混填体作为路基填料。但是,由于填料的颗粒粒度变化很大且难以控制,加之含水率极不均匀,使得在实际工程中,土石混填体路基的质量得不到保证,致使修筑的路基产生大量的沉陷或坍塌,从而导致路基结构过早破坏,影响使用效率的发挥。加之南方山区雨水较多,土石混填路基长期处于湿润状态,也对土石混填路基的性能产生很大的影响。本文针对存在的问题,为了深入了解土石混填体力学特性、变形特征及路用性能,对土石混填体进行了一系列的研究,主要工作有：(1)在已有研究的基础上,并全面考虑含水量、含石量、岩性、土性等因素的影响作用,采用YS30-3型应力路径三轴剪切试验机,并基于正交试验方法进行了一系列土石混填体大型三轴压缩研究。试验结果表明：在三轴受力条件下,土石混填体在低围压下的应变软化特征不明显,试样的粘聚力c普遍较低而内摩擦角j则比较高,且内摩擦角φ更容易受其它因素的影响而发生显著的变化；含石量对土石混填体的抗剪强度影响程度最大,随试样中的含石量从25%增加到70%,其内摩擦角φ从34.54°近似线性增长至46.39°；含石量和围压分别是影响土石混填体体变特性最主要的内因和外因,即在含水率、岩性、土性相同的情况下含石量越低试样高压剪缩性越明显,含石量越高其低压剪胀性越明显。(2)采用FLAC 3D软件,根据大型三轴试验的到试验参数,建立了一个土石混填体高填路基的概化模型,对土石混填路基进行了数值模拟分析,分析研究了各因素对土石混填路基稳定性的影响,并对土石混填路基的施工提出了一些指导意见。(3)针对正常和洒水浸泡两种情况,在特制的地槽中,制作了两个土石混填路基模型,并对路基模型进行分级加载,研究土石混填路基的受荷沉降变形特性。试验结果表明：对于正常情况,土石混填路基的结构性较好,在到达极限荷载前,其p-s近似呈线性关系,到达极限荷载时路基边坡突然出现大变形沉降,并发生破坏；而对于洒水浸泡情况,沉降变形发展缓慢,没有明显的拐点,其极限荷载相对于正常情况也更小一些,含水量对土石混填路基的沉降变形,承载力都有比较显著的影响；对土石混填路基土压力的测量结果发现,应力在路基中的扩散传递具有不对称性,荷载的影响深度也有不对称性。
[Abstract]:With the rapid development of the infrastructure construction in the southern mountainous area, more and more earth and rock mixed fillers are used as subgrade fillers in the subgrade engineering construction. However, because the particle size of fillers varies greatly and it is difficult to control, and the moisture content is very uneven, the quality of embankment can not be guaranteed in actual engineering, resulting in a large number of subgrade subsidence or collapse. Thus causes the subgrade structure to destroy prematurely, affects the use efficiency display. In addition, there is more Rain Water in the southern mountainous area, and the soil-rock embankment is in a wet state for a long time, which also has a great influence on the performance of the soil-rock embankment. Aiming at the existing problems, in order to understand the mechanical characteristics, deformation characteristics and road performance of earth and rock fill, a series of researches have been carried out in this paper, the main work of which is: 1) on the basis of existing research, and considering the water content in an all-round way. The influence of rock content, lithology and soil properties on large triaxial compression of a series of earth and rock mixed fillers was studied by using YS30-3 triaxial shear testing machine and orthogonal test method. The test results show that under the condition of triaxial loading, the strain softening characteristics of earth-rock mixed fill under low confining pressure are not obvious, the cohesive force c is generally lower and the internal friction angle j is higher. Moreover, the internal friction angle 蠁 is more easily influenced by other factors, and the content of stone has the greatest influence on the shear strength of the soil and rock mixture. With the increase of rock content from 25% to 70%, the angle of internal friction increases linearly from 34.54 掳to 46.39 掳. In the case of the same soil properties, the lower the rock content, the more obvious the shear shrinkage at high pressure, and the higher the rock content, the more obvious the dilatancy at low pressure.) the FLAC 3D software is used, and according to the parameters of the large triaxial test, In this paper, a general model of the embankment with soil and rock filling height is established, and the numerical simulation analysis of the subgrade is carried out, and the influence of various factors on the stability of the embankment is analyzed and studied. At the same time, some guiding opinions are put forward for the construction of earth-rock mixed filling subgrade. Aiming at the two situations of normal and sprinkling soaking, two soil-filled subgrade models are made in the specially made geosyncline, and the subgrade models are graded loaded. In this paper, the settlement and deformation characteristics of embankment filled with earth and rock are studied. The test results show that the structure of the embankment filled with earth and rock is better for normal condition. Before the ultimate load is reached, the p-s of the embankment is approximately linear. When the ultimate load is reached, large deformation and settlement of the embankment slope occur suddenly, and the failure occurs. For sprinkler immersion, the settlement deformation develops slowly, there is no obvious inflection point, and the ultimate load is smaller than the normal condition. The water content has a significant effect on the settlement deformation and bearing capacity of soil-rock embankment. It is found that the diffusion of stress in embankment is asymmetrical and the influence depth of load is asymmetric.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.1

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