龙泉山红层泥岩分布规律及其工程性质研究

发布时间：2018-04-18 16:27

本文选题：红层泥岩 + 分布　；参考：《西南交通大学》2017年硕士论文

【摘要】：随着近年来,西南地区基础设施建设的大力开展,红层区泥岩诱发的自然灾害在实际工程建设中引起了建设者们广泛的关注。红层泥岩具有保水性强,抗风化能力弱,遇水后岩体易膨胀且结构面抗剪强度大幅度下降,失水后又产生收缩、崩解等工程特性,再加上红层区泥岩分布广泛,因此,以红层泥岩的分布规律为切入点,对泥岩的工程特性及其微观机理进行研究具有较强的现实意义。本文主要通过对龙泉山地区的野外调查及室内试验,对该地区红层泥岩的分布,膨胀性、抗剪强度等工程参数与微结构的相关性进行了分析,得出以下成果:1.通过阅读大量的文献及相关的地质资料,对龙泉山地区主要地层分布,岩性、水文、各地层含泥岩的岩组数量及泥岩所占百分含量进行了统计分析,认为该地区主要地层分布为侏罗系和白垩系,岩性大都为泥岩、砂岩、粉砂岩等,且侏罗系含泥岩岩组的数量要多于白垩系。2.五组泥岩重塑土的室内直剪及膨胀率试验数据表明,对于侏罗系及白垩系地层中的泥岩皆存在膨胀性,其中,灌口组泥岩和上沙溪庙组紫色泥岩膨胀性较强;而抗剪强度参数c、ψ值,随含水率的变化,均呈现规律性变化。随含水率的增大,黏聚力c值先增大后减小,即存在一个最优含水率值,经测得,该值位于试样塑限值附近。内摩擦角ψ值,随含水率的增大,呈非线性的降低。3.矿物成分及Fe_2O_3的量与试样的抗剪强度均存在一定的相关性。当富含黏土矿物的泥岩试样中,蒙脱石的含量达到一定值时,此时该试样主要体现蒙脱石的工程特性;同时Fe_2O_3含量的变化,对含蒙脱石矿物试样的黏聚力值增长显著,对内摩擦角值减小同样显著,最终随着Fe_2O_3含量的增大,抗剪强度参数值均趋于平缓。4.微结构的结构类型,孔隙数量、颗粒排列的密集及定向程度、结构连接力的强弱均对抗剪强度及膨胀势的大小产生影响。其中,片状体形成的片状结构、面-面叠聚体的密集定向排列、较弱的结构连接形式是导致膨胀势较高的一个关键因素。而孔隙数量较多的,在含水率较低时,抗剪性能较差。
[Abstract]:With the development of infrastructure construction in Southwest China in recent years, the natural disasters induced by mudstone in the red bed area have aroused widespread concern of the constructors in practical engineering construction.Red mudstone has engineering characteristics such as strong water retention, weak weathering resistance, easy expansion of rock mass after water treatment, large decrease in shear strength of structural plane, shrinkage and disintegration after losing water, and the mudstone in red bed area is widely distributed, therefore,It is of great practical significance to study the engineering characteristics and microscopic mechanism of mudstone from the point of view of the distribution law of red mudstone.Based on field investigation and laboratory test in Longquanshan area, the correlation between engineering parameters such as distribution, expansion, shear strength and microstructure of red mudstone in this area is analyzed in this paper, and the following results are obtained: 1.By reading a large number of documents and related geological data, the distribution, lithology, hydrology, the number of mudstone formations and the percentage of mudstone in the Longquanshan area are analyzed statistically.It is considered that the main strata in this area are Jurassic and Cretaceous, and the lithology is mostly mudstone, sandstone, siltstone and so on, and the number of Jurassic mudstone formation is more than Cretaceous. 2.Five groups of mudstone remolded soil are tested by direct shear and expansion test. The results show that there is swelling of mudstone in Jurassic and Cretaceous strata, among which mudstone of Guankou formation and purple mudstone of Upper Shaximiao formation have strong expansibility.However, the shear strength parameters c and 蠄 change regularly with the change of moisture content.With the increase of moisture content, the cohesion C value first increases and then decreases, that is, there exists an optimal moisture content value, which is located near the plastic limit value of the sample.The angle 蠄 of internal friction decreases with the increase of moisture content.There is a certain correlation between the mineral composition and the amount of Fe_2O_3 and the shear strength of the sample.When the content of montmorillonite reaches a certain value in the mudstone sample rich in clay minerals, the sample mainly embodies the engineering characteristics of montmorillonite, and the change of Fe_2O_3 content increases the cohesion value of montmorillonite mineral sample significantly.The value of internal friction angle decreased significantly, and finally, with the increase of Fe_2O_3 content, the shear strength parameters tended to be flat. 4.The structural types, the number of pores, the density and orientation of particle arrangement, and the strength of structural connection force all affect the shear strength and expansion potential.One of the key factors leading to the higher expansion potential is the flake structure formed by the flake, the dense and directional arrangement of the facial-plane superpolymer, and the weak structural connection form.However, when the water content is low, the shearing property is poor when the number of pores is more.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU452

【参考文献】