季冻区冻融作用下路基土性能及微观结构分析
发布时间：2018-07-28 18:19
【摘要】：在季冻区,由于特殊气候的影响,道路普遍会受到冻融作用的影响而产生病害,但是对于道路路基病害的研究还没有引起国内研究人员的足够重视。为了弄清冻融作用下季冻区路基土的强度性能的变化,选择黑龙江省3条有代表性的等级公路,冬季前后分别调查路基土含水率,研究其随季节变化情况,判断路基的干湿状况；取土样进行室内不同条件下路基土冻融强度试验,研究冻融作用下路基土强度的变化规律；采用电镜扫描研究冻融后路基土的微观变化机理。 调查发现春季冻土融化后路基土含水率较冬季冻结前的含水率有所增大,并且大多数调查路段路基处于干燥或中湿状态。室内试验表明：在冻融循环次数相同时,土体的回弹模量随压实度的降低而减小,随含水率的降低而增大,且压实度越低,含水率对土体回弹模量的影响系数越大,在含水率和压实度条件相同时,冻融作用能够使土体的回弹模量降低,且冻融循环次数越多,回弹模量衰减值越大,6次冻融之后,其模量降低基本稳定：冻融循环作用使土体的黏聚力降低,内摩擦角增大,其中粉质粘土的黏聚力受冻融作用的影响最大；随着压实度的增加,各类土的黏聚力和内摩擦角值都有不同程度的增加,其中砂性土黏聚力变化最为明显；随着含水率的增加,土体的黏聚力和内摩擦角都会降低,而粉质粘土的黏聚力和内摩擦角受含水率的影响最大。微观电镜扫描发现土体在经过冻融循环作用后内部结构发生改变,颗粒之间的孔隙得以发育,颗粒之间相互接触变得比较松散,导致土的力学性能下降。
[Abstract]:Due to the influence of special climate, the road will be affected by freeze-thaw process, but the research of road roadbed disease has not been paid enough attention to by domestic researchers. In order to find out the change of strength performance of subgrade soil in freeze-thaw region, three representative grade highways in Heilongjiang Province were selected. The moisture content of subgrade soil was investigated before and after winter, and the variation of soil moisture with seasons was studied. To judge the dry and wet condition of roadbed, to test the freeze-thaw strength of subgrade soil under different indoor conditions, and to study the change rule of roadbed soil strength under freeze-thaw action, and to study the microcosmic change mechanism of roadbed soil after freeze-thaw by electron microscope scanning. It is found that the moisture content of subgrade soil after frozen soil thawing in spring is higher than that before freezing in winter, and the subgrade of most sections of investigation is in dry or medium wet state. The results of laboratory tests show that when the number of freeze-thaw cycles is the same, the elastic modulus of soil decreases with the decrease of compaction degree, and increases with the decrease of moisture content, and the lower the compaction degree, the greater the influence coefficient of moisture content on the resilience modulus of soil. Under the same conditions of moisture content and compaction, the springback modulus of soil can be reduced by freeze-thaw action, and the more times of freeze-thaw cycle, the greater the attenuation value of springback modulus is after 6 times freeze-thaw. Its modulus is basically stable: freezing and thawing cycle makes the cohesive force of soil decrease and the angle of internal friction increases, among which the cohesion of silty clay is most affected by freezing and thawing, and with the increase of compaction, The cohesive force and internal friction angle of all kinds of soils are increased to some extent, among which the cohesion of sandy soil is the most obvious, and with the increase of water content, the cohesive force and internal friction angle of soil will decrease. The cohesion and internal friction angle of silty clay are most affected by moisture content. It was found by SEM that the internal structure of soil changed after freeze-thaw cycle, the pores between particles developed, and the contact between particles became loose, which resulted in the decline of mechanical properties of soil.
【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1
本文编号：2151200
[Abstract]:Due to the influence of special climate, the road will be affected by freeze-thaw process, but the research of road roadbed disease has not been paid enough attention to by domestic researchers. In order to find out the change of strength performance of subgrade soil in freeze-thaw region, three representative grade highways in Heilongjiang Province were selected. The moisture content of subgrade soil was investigated before and after winter, and the variation of soil moisture with seasons was studied. To judge the dry and wet condition of roadbed, to test the freeze-thaw strength of subgrade soil under different indoor conditions, and to study the change rule of roadbed soil strength under freeze-thaw action, and to study the microcosmic change mechanism of roadbed soil after freeze-thaw by electron microscope scanning. It is found that the moisture content of subgrade soil after frozen soil thawing in spring is higher than that before freezing in winter, and the subgrade of most sections of investigation is in dry or medium wet state. The results of laboratory tests show that when the number of freeze-thaw cycles is the same, the elastic modulus of soil decreases with the decrease of compaction degree, and increases with the decrease of moisture content, and the lower the compaction degree, the greater the influence coefficient of moisture content on the resilience modulus of soil. Under the same conditions of moisture content and compaction, the springback modulus of soil can be reduced by freeze-thaw action, and the more times of freeze-thaw cycle, the greater the attenuation value of springback modulus is after 6 times freeze-thaw. Its modulus is basically stable: freezing and thawing cycle makes the cohesive force of soil decrease and the angle of internal friction increases, among which the cohesion of silty clay is most affected by freezing and thawing, and with the increase of compaction, The cohesive force and internal friction angle of all kinds of soils are increased to some extent, among which the cohesion of sandy soil is the most obvious, and with the increase of water content, the cohesive force and internal friction angle of soil will decrease. The cohesion and internal friction angle of silty clay are most affected by moisture content. It was found by SEM that the internal structure of soil changed after freeze-thaw cycle, the pores between particles developed, and the contact between particles became loose, which resulted in the decline of mechanical properties of soil.
【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1
【参考文献】
相关博士学位论文 前1条
1 韩春鹏;石灰处治土路基冻融作用特性研究[D];东北林业大学;2011年
，本文编号：2151200
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