淮安膨胀土的水力—力学特性

发布时间：2018-04-01 11:10

本文选题：淮安膨胀土　切入点：膨胀力　出处：《上海大学》2013年硕士论文

【摘要】：随着我国国民经济和交通运输事业的发展，高速公路作为一个国家走向现代化的桥梁，在现代交通业的建设中起着至关重要的作用。在我国庞大的高速公路网中，很多高速公路建设在膨胀土地基上。作为典型的“问题”土，膨胀土地基容易在湿胀干缩的过程中开裂破坏，其工程灾害问题已引起我国工程界和学术界的高度关注。本论文在查阅和整理国内外相关文献基础上，对取自江苏省淮安地区的膨胀土进行试验研究，具体做了如下几个方面的研究工作： 1、通过一系列土的基本物理试验，得出了淮安膨胀土的基本物理性质；根据试验结果，判断出土样颗粒级配良好，天然土样处于软塑状态，该土样属于弱膨胀土，试验同时还得到了该土样在饱和状态下的压缩指标。 2、使用三轴试验仪对压实淮安膨胀土进行固结排水剪切试验，研究了其强度和变形特性，得到其抗剪强度指标。试验结果表明：在相同初始孔隙比条件下，剪切时的围压对于压实淮安膨胀土的应力比-应变曲线有明显影响，围压较大的应力比-应变曲线较低，应力比峰值也较小；剪切时围压较大的体变更倾向于剪缩。侧向应变也较小。在相同围压条件下，初始孔隙比对应力比-应变曲线稍有影响，对体变有明显影响，初始孔隙比较大的更倾向于剪缩。 3、使用固结仪对压实淮安膨胀土进行浸水膨胀变形试验和膨胀力试验，研究其膨胀特性。试验结果表明：浸水引起的膨胀变形（膨胀率）随着上覆荷载、初始含水量的增大而减小，随着初始干密度增大而增大；在相同初始孔隙比条件下，浸水变形稳定后的孔隙比和上覆荷载的对数呈线性关系；膨胀力随初始孔隙比的减小而增大，且膨胀力与初始孔隙比呈良好的线性关系。 4、使用压力板法、滤纸法和蒸汽平衡法三种不同控制或量测吸力的试验方法，分别对其压实土样进行土水特性试验，得出了吸力范围为0~378MPa的土水特征曲线。试验结果表明：初始干密度相近时，在低吸力范围内脱湿曲线和吸湿曲线有明显的滞回现象，，当吸力大于100MPa时，滞回现象基本消失。滤纸法测出的土水特征曲线落在主脱湿和主吸湿曲线的滞回圈内；由蒸汽平衡法所得出的高吸力范围土水特征曲线可以看出，吸力接近于1000MPa时含水量接近于零。根据滤纸法的试验结果，土水特征曲线用含水量和吸力关系表示时，不同初始干密度试样的土水特征曲线相差不大，说明干密度对此类土水特征曲线的影响不大；而用饱和度和吸力关系表示时，当吸力较小时，干密度大的土水特征曲线处于干密度小的右上方，当吸力较大时，干密度对土水特征曲线的影响逐渐减小。
[Abstract]:With the development of national economy and transportation in China, expressway, as a bridge to modernization, plays an important role in the construction of modern transportation industry.In the huge highway network of our country, many freeways are built on expansive soil foundation.As a typical "problem" soil, expansive soil foundation is easy to crack and destroy in the process of wet expansion and shrinkage, and its engineering disaster has attracted great attention of engineering and academic circles in China.On the basis of consulting and collating domestic and foreign relevant literature, this paper carries on the experimental research to the expansive soil from Huaian area of Jiangsu Province, and does the following research work:1. Through a series of basic physical tests of soil, the basic physical properties of Huai'an expansive soil are obtained, according to the test results, the particle gradation of soil sample is good, the natural soil sample is in soft plastic state, and the soil sample belongs to weakly expansive soil.At the same time, the compression index of the soil sample in saturated state was obtained.2. The consolidation and drainage shear tests of compacted Huai'an expansive soil were carried out by using a triaxial test instrument. The strength and deformation characteristics of the soil were studied, and the shear strength index was obtained.The larger confining pressure changes tend to shrink during shear.The lateral strain is also small.Under the same confining pressure, the initial porosity ratio has a slight effect on the stress-to-strain curve, which has obvious influence on the bulk deformation, and the larger initial porosity is more inclined to shear shrinkage.3. The swelling deformation test and expansion force test of compacted Huai'an expansive soil were carried out by means of consolidation instrument, and its expansion characteristics were studied.The experimental results show that the swelling deformation (expansion ratio) caused by soaking decreases with the increase of the initial water content and increases with the increase of the initial dry density, and under the same initial void ratio,The relationship between the porosity ratio and the logarithm of the overlying load is linear, and the expansion force increases with the decrease of the initial void ratio, and there is a good linear relationship between the expansion force and the initial void ratio.4. Using three test methods of controlling or measuring suction, pressure plate method, filter paper method and steam equilibrium method, the soil-water characteristics of compacted soil samples are tested, and the characteristic curves of soil and water with suction range of 0~378MPa are obtained.The experimental results show that the dehumidification curve and the hygroscopic curve have obvious hysteretic phenomena in the range of low suction when the initial dry density is close. When the suction is larger than 100MPa, the hysteretic phenomenon basically disappears.The soil-water characteristic curve measured by filter paper method falls in the hysteresis loop of the main dehumidification and main moisture absorption curves, and the soil-water characteristic curve in the high suction range obtained by steam equilibrium method shows that the water content is close to zero when the suction is close to that of 1000MPa.According to the test results of filter paper method, when soil water characteristic curve is expressed by water content and suction relationship, the difference of soil water characteristic curve of different initial dry density sample is not different, which indicates that dry density has little influence on soil water characteristic curve.When the saturation and suction relation are used, when the suction is small, the soil water characteristic curve with high dry density is in the upper right of the dry density, and the influence of dry density on the soil water characteristic curve decreases gradually when the suction is larger.
【学位授予单位】：上海大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU443

【参考文献】