冻融循环下砒砂岩重塑土力学性能及本构模型的研究

发布时间：2018-04-13 10:47

本文选题：砒砂岩重塑土 + 冻融循环　；参考：《内蒙古农业大学》2017年硕士论文

【摘要】：冻胀和融沉是寒区工程所面临的两大主要工程病害,常导致房屋开裂、倾斜及变形,导致铁路、公路涵洞端翼墙裂缝、外倾;导致公路翻浆冒泥,铁路路基变形、开裂等。近年来,给当地的工程建设造成极大的难题,所以针对砒砂岩重塑土在冻融循环作用下的力学机理研究就显得尤为重要。砒砂岩所在地区属于典型的温带大陆性气候,四季分明,分布着大量的季节性冻土。在冬季昼夜温差极大,晚间温度快速下降使土体产生"冻结",白天在太阳辐射照耀下温度升高,产生"融解"现象,这种冻融循环作用改变了砒砂岩土壤颗粒的结构连接和排列方式,从而影响其力学性质。本文以内蒙古鄂尔多斯市南部准格尔旗的紫红色砒砂岩重塑土样为研究对象,通过对不同冻融循环次数、不同围压、不同含水率下的常规三轴剪切试验,研究砒砂岩的力学性能变化,并确定了砒砂岩本构模型。研究结果表明:在相同的冻融循环次数下,砒砂岩重塑土样的黏聚力值均随含水率增大而减小,内摩擦角值随着含水率的增加呈现上下波动;在相同的冻融循环次数下,随着围压的增大,抗剪强度峰值呈线性增长趋势,因此,冻融循环对抗剪强度的影响主要表现在对黏聚力的影响。通过对应力-应变曲线变化情况的分析,引入反应强度变化的参数、劣化系数,分析了在不同冻融循环次数下,砒砂岩劣化系数的变化情况,得出影响砒砂岩重塑土强度变化的参数主要为黏聚力C值的变化;在此基础上,分析了砒砂岩峰值强度与残余强度的关系,得出砒砂岩重塑土的应力-应变曲线的软、硬化特性。根据邓肯-张模型建立了以含水率、围压为影响因素的砒砂岩重塑土本构模型。并应用该模型对砒砂岩土的应力-应变关系进行了分析预测,模型预测结果与实测结果接近,表明该模型能较好地反映砒砂岩重塑土在不同含水率、不同围压下的本构关系。
[Abstract]:Frost heaving and thawing are two major engineering diseases in cold region, which often lead to cracks, inclines and deformations of buildings, cracks of end wing walls of railway and highway culverts, and sloping of mud, deformation of railway subgrade, cracking of railway subgrade, etc.In recent years, great problems have been caused to local engineering construction, so it is very important to study the mechanics mechanism of soft rock remolded soil under freeze-thaw cycle.The soft rock is a typical temperate continental climate with four distinct seasons and a large number of seasonal permafrost.In winter, the temperature difference between day and night is very great. The rapid drop of temperature at night causes the soil to "freeze". During the day, the temperature rises under the sun radiation, resulting in the phenomenon of "melting".The freezing and thawing cycle has changed the structural connection and arrangement of soil particles in arsenopyst soil, thus affecting its mechanical properties.In this paper, the remolded soil samples of purple arsenite in Zhungeer Banner in southern Ordos, Inner Mongolia, were studied. The conventional triaxial shear tests were carried out under different freezing and thawing cycles, different confining pressures and different water contents.The mechanical properties of Pisha sandstone were studied and the constitutive model of Pisha sandstone was established.The results show that under the same freezing and thawing cycles, the cohesion of the remolded samples decreases with the increase of water content, and the angle of internal friction fluctuates with the increase of water content, and at the same times of freeze-thaw cycles,With the increase of confining pressure, the peak value of shear strength increases linearly. Therefore, the influence of freeze-thaw cycle shear strength is mainly on the cohesion.By analyzing the variation of stress-strain curve and introducing the parameters of reaction intensity change and degradation coefficient, the variation of deterioration coefficient of arsenopyst under different freeze-thaw cycles is analyzed.On the basis of this, the relationship between peak strength and residual strength of Pisha sandstone is analyzed, and the soft stress-strain curve of soft rock remolded soil is obtained.Hardening characteristics.Based on Duncan-Zhang model, a constitutive model of soft rock remolded soil was established with water content and confining pressure as the influencing factors.The model is used to analyze and predict the stress-strain relationship of Pisha sandstone soil, and the predicted results are close to the measured results. It shows that the model can well reflect the constitutive relationship of Pisha sandstone remolded soil under different water content and confining pressure.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU43

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