昆明长水机场红土粒度成分方法研究

发布时间：2018-03-30 02:02

本文选题：红土　切入点：成因　出处：《昆明理工大学》2015年硕士论文

【摘要】：红土以其特殊的物理、水理及力学性质区别于一般的黏性土,由于经济的飞速发展,在红土分布区的工程建设与日俱增,红土特殊的工程性质对工程建筑安全稳定影响日益凸显。昆明长水机场位于滇东高原盆地昆明岩溶高原湖盆亚区,昆明盆地东北部,区内红土发育,红土成因类型及其工程性质较为复杂,对机场各类建筑物安全稳定影响较大。由于传统红黏土理论存在不足和缺陷,机场岩土工程勘察成果把工程区砂页岩和玄武岩等硅酸盐岩经红土化作用形成的红土简单粗糙地分类命名为“红黏土”,未能客观真实地反映红土的成因类型及工程特性,使机场岩土工程勘察成果存在缺陷。红土特殊的团粒结构,使其表现出天然密度较小,天然含水量、饱和度、孔隙比较大,液限、塑限高,从而导致红土在物理、水理性质具有软土的特性,在力学性质方面又表现出砂质粉土的特点,使得红土工程地质特性非常特殊。红土的团粒结构是红土化作用的直接结果,红土团粒的粒径大小、含量多少,以及组成团粒结构单元体的数量等是影响红土特殊工程性质的基本因素。由于学术界对红土成因及分类研究存在严重分歧,对红土粒度成分的分析研究缺乏系统性,现有实验规程规范对红土粒度成分测试规定缺乏客观科学依据,使对红土粒度成分的分析结果离散性太大,毫无规律可循,更未能准确地反映红土的团粒粒径大小、团粒数量及结构单元体含量等。本文按照导师符必昌建立的红土成因理论所确立的长水机场红土成因类型,主要对长水机场砂页岩(ε2d)和玄武岩(P2e)残积红土的粒度成分在不同分散剂类型、不同浓度下的粒度成分变化规律及粒度成分特征值进行系统分析研究,客观揭示各种分散剂对不同红土类型的作用效果、不同红土类型粒度成分的差异及主要特征,为进一步综合系统地分析研究红土的工程地质特性奠定基础。昆明长水机场砂页岩和玄武岩经红土化作用形成了相应的残积红土,根据红土化作用程度可把残积红土划分成典型红土、块状红土、散粒红土。寒武系中统陡坡寺组砂页岩残积红土因较强侵蚀作用,只保留了块状红土、散粒红土。而二叠系中统峨眉山组玄武岩残积红土剖面保存较好,其典型红土、块状红土、散粒红土均得以保存。本文采用4种分散剂在不同浓度条件下分别对上述5类土样进行粒度成分的综合试验研究。本文对上述5类红土样品的粒度成分试验进行总结分析得出：(1)在未加分散剂条件下,砂页岩和玄武岩各自的残积红土主要集中在粉粒组,表明块状红土和散粒红土土体颗粒极不均一,以粉粒团粒体为主的状态存在,不同红土化作用阶段形成的残积红土在分散效果方面各自具有共性又具有特性；(2)双氧水用于去除含有机质土中的有机质时有一定效果,但单独使用时效果不佳；选择单独使用的分散剂时,应该逐步放弃使用氨水和双氧水,但可以考虑结合其它分散剂共同使用；(3)此4类分散剂普遍存在一个共同点,即在一定范围内分散效果随着分散剂浓度增加而加强,当浓度到达某个数值以后分散效果发生质变,达到最佳分散区间及最佳分散值,随后分散效果逐步下降；(4)同一土样采用不同的分散剂及浓度值,所得到的粒组含量受到很大影响,可能得出不同的定名,致使红土的定名和工程性质与其实际状况存在一定差异,分散剂的种类及其浓度值对粒度成分试验至关重要；(5)砂页岩残积红土及玄武岩残积红土的团粒结构实质就是由胶粒为主胶结而成的粉粒团体,具有假集合体及遇水稳定的抗水集合体的特性；(6)散粒红土建议使用3%-5%六偏磷酸钠作为分散剂,典型和块状红土建议使用6%-8%六偏磷酸钠作为分散剂分散效果更佳；(7)规范建议的分散剂的浓度值,测试结果大多没有达到峰值,说明红土作为特殊黏性土在粒度成分方面具有特殊性,区别于一般黏性土,应给与区别对待。
[Abstract]:The red soil is distinguished from the general clay by its special physical , water and mechanical properties . Due to the rapid development of the economy , the engineering construction in the red soil distribution area is increasing day by day . The special engineering property of the laterite is more and more obvious to the construction safety and stability of the project . In this paper , a systematic analysis of the characteristics of red earth ' s grain size composition is carried out in this paper . The results show that the characteristics of the red earth ' s grain size , the size and the content of the granular components of the red soil are very special .
( 2 ) When the hydrogen peroxide is used to remove organic matter contained in organic matter , it has certain effect , but the effect is not good when used alone ;
When the dispersant used alone is selected , ammonia water and hydrogen peroxide should be gradually discarded , but it can be used in combination with other dispersants ;
( 3 ) There is a common point in the 4 kinds of dispersing agents , that is , the dispersion effect is enhanced with the increase of the concentration of the dispersant in a certain range . When the concentration reaches a certain value , the dispersion effect is changed , the optimal dispersion range and the optimal dispersion value are achieved , and then the dispersion effect is gradually decreased ;
( 4 ) In the same soil sample , different dispersing agents and concentration values are adopted , the content of the obtained grain groups is greatly influenced , and different orders can be obtained , so that the definite name and engineering property of the red soil are different from the actual conditions , and the type and the concentration value of the dispersing agent are very important to the particle size component test ;
( 5 ) The grain structure of the eluvial red soil and the basalt residual red soil of the sand shale is basically a grain group composed of colloidal particles , which has the characteristics of a false aggregate and an anti - water aggregate stable in water ;
( 6 ) It is suggested that using 3 % -5 % sodium hexaaluminate as the dispersing agent , and 6 % -8 % sodium hexaaluminate can be used as the dispersing agent to disperse the red soil .
( 7 ) According to the concentration value of the dispersant in the specification , most of the test results do not reach the peak value , indicating that the red soil has special characteristics in the aspect of particle size composition as a special clay , and is different from the general clay , and should be treated differently .

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.132

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