粉土击实过程中土中应力及击实后热物理参数测试

发布时间：2018-01-23 13:20

本文关键词： 粉土孔隙率饱和度土压力热物理参数　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：粉土在我国广泛分布。因其特殊的工程性质,在地基、路基中作为填土材料,粉土被认为是最差的材料之一。由于山西地区特殊的地形、地貌,在道路建设和工程建设中常采用填土技术。而填土的击实质量,直接关系到上部结构的安全和正常运营。同时,建设地下交通体系是有效地缓解城市交通拥挤和用地短缺的重要途径之一。因此,针对粉土击实特性的研究,击实过程中的土中应力特性研究以及准确获得击实粉土的热物理性质的研究,不仅补充完善了岩土材料击实性能和热物理性质的认识,而且对解决工程实际问题具有重要意义。为此,本文针对山西地区的粉土进行了室内击实试验,分析了击实能、含水量、击实次数和土层厚度对粉土击实过程中的土压力和击实锤的冲击力的影响;对击实后的粉土测定热物理参数,分析了孔隙率和饱和度与三个热物理参数的关系。试验结果表明:(1)在同一击实能下,分5层击实时土样的最优含水量和最大干密度均略大于分3层击实时的。(2)无论击实含水量为多少,击实第一层土时,实测的土中压力随着击实次数的增加而提高,在最后一击时达到最大值。而击实锤的冲击力在含水量与最优含水量相差2%的范围内,均不发生变化,维持在12.5k N左右。对第二层或第三层土进行击实时,击实含水量在最优含水量的干侧,土中的压力随击实次数增加而提高,但是提高幅度小于第一层时;在最优含水量的湿侧击实时,土中的压力从某一击开始不再增加,保持不变。随着含水量的增加,每层土的最终土压力值和最大击实锤冲击力先增加后减小。随着击实能的增加,第一层土的最终土压力值逐渐增加;对第二层土或第三层土进行击实时,在最优含水量和最优含水量的偏干侧,每层土的最终土压力值在增加;而在最优含水量的偏湿侧,每层土的最终土压力值逐渐减小。在最优含水量的偏干侧,第一层土的最大击实锤冲击力随着击实能的增大几乎不变,第二至五层土的最大冲击力有所增加。土压力随着击实厚度的增加以指数函数的形式降低。(3)土样的导热系数和比热容随着孔隙率的增大表现为线性减小,导温系数则逐渐增大。随着饱和度的增加,土样的导热系数和比热容曲线均呈现先上升再下降的趋势;导温系数则相反,呈现先降低后增加的趋势。另外,热物理参数与孔隙率、饱和度均具有良好的相关性。
[Abstract]:Silt is widely distributed in China. Because of its special engineering properties, silt is regarded as one of the worst materials in foundation and roadbed. Fill technology is often used in road construction and engineering construction. The compaction quality of fill is directly related to the safety and normal operation of superstructure. The construction of underground traffic system is one of the important ways to effectively alleviate urban traffic congestion and land shortage. Therefore, the study on the characteristics of silt compaction. The study of the stress characteristics in the compaction process and the accurate obtaining of the thermophysical properties of the compacted silt not only complements the understanding of the compaction properties and thermophysical properties of the rock and soil materials. And it is of great significance to solve the practical problems of engineering. Therefore, this paper carried out laboratory compaction test for silt in Shanxi area, and analyzed compaction ability and water content. The influence of compaction times and soil thickness on soil pressure and impact force of compaction hammer during silt compaction; The relationship between porosity and saturation and three thermophysical parameters is analyzed for the silt determined by compaction. The experimental results show that the porosity and saturation are under the same compaction energy. The optimal moisture content and maximum dry density of the soil samples in 5 layers are slightly larger than that of the real time soil samples in 3 layers.) no matter how much the compacted water content is, the first layer soil is compacted. The measured pressure in the soil increases with the increase of compaction times and reaches the maximum at the last strike, while the impact force of the hammer does not change in the range of 2% between the water content and the optimum water content. The compaction water content is on the dry side of the optimum water content, and the pressure in the soil increases with the increase of compaction times. But when the increase is less than the first layer; At the wet side strike of the optimal water content, the pressure in the soil does not increase from a certain strike, and remains unchanged. With the increase of water content. The final earth pressure and the maximum hammer impact force of each layer of soil firstly increase and then decrease. With the increase of compaction energy, the final earth pressure value of the first layer of soil increases gradually. When the second layer soil or the third layer soil is hit in real time, the final soil pressure of each layer is increasing on the dry side of the optimal water content and the optimal water content. On the wet side of the optimal moisture content, the final soil pressure of each layer of soil gradually decreases. On the dry side of the optimum moisture content, the maximum impact force of the first layer of soil is almost unchanged with the increase of compaction energy. The maximum impact force of the second to fifth layer soil increases. The soil pressure decreases with the compaction thickness by exponential function.) the thermal conductivity and specific heat capacity of the soil sample decrease linearly with the increase of porosity. With the increase of saturation, the thermal conductivity and specific heat capacity curve of soil samples increased first and then decreased. On the contrary, the thermal conductivity coefficient decreased first and then increased. In addition, there was a good correlation between thermal physical parameters and porosity and saturation.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU411

【相似文献】