冻融循环作用后压实粉质粘土的静动力学性能研究

发布时间：2018-03-19 16:52

本文选题：冻融循环　切入点：压实粉质粘土　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：我国是世界上第三冻土大国，其中冻结深度大于1.5m且对工程有直接影响的深季节冻土面积达到了3.67×106km2。季节冻土地区路基填土受冻融循环作用的影响，其物理、水理和力学性能发生改变，而且在长期重载作用下，不可避免地发生了翻浆、融沉等典型病害，降低了道路的路用性能和服务年限，由此制约地方经济健康有序的发展，而且耗费了大量人力与财力维修。为了明确季节冻土区重载汽车荷载作用下路基病害发生的过程和机理，深化对冻融循环后压实粉质粘土力学性能的认识，同时为后续研究工作提供数据支持，本文采用不固结不排水静三轴试验和共振柱试验，，开展冻融循环作用后压实粉质粘土的力学性能试验工作，主要完成工作包括：（1）使用自动控温箱进行封闭三向冻融循环试验，对冻融循环中试样的温度和含水率进行监测，分析其变化规律，并确定冻结、融化的时间和温度；使用自主研发的土工材料体积变化测试仪和人工测量两种方法，对冻融循环过程中试样的质量和体积进行测量，获得各物理参数的变化规律。（2）采用应变控制式静三轴仪对冻融循环后压实粉质粘土的静力学性能进行测试，研究围压、压实度、含水率、冻融循环次数等因素对压实粉质粘土的静力学性能影响，并对试样的破坏形式进行了微观和宏观的分析；对压实粉质粘土试样的主应力差与轴向应变关系进一步分析，得到了不同因素对破坏强度、切线模量、凝聚力和内摩擦角的影响规律；进而采用多元非线性回归方法，提出了破坏强度、切线模量、凝聚力和内摩擦角的预估公式。（3）采用共振柱试验仪对冻融循环后压实粉质粘土的动力学参数进行测试，研究围压、压实度、含水率、冻融循环次数等因素对其动力学性能影响；得到了不同因素对压实粉质粘土的动剪切模量、阻尼比的影响规律；基于双曲线模型，将动剪切应变区域进行拓展。并提出了最大动剪切模量和最大阻尼比的经验预估公式。
[Abstract]:China is the third largest country of frozen soil in the world, in which the depth of freezing is more than 1.5 m and the area of frozen soil in deep season has reached 3.67 脳 10 6 km 2. The subgrade fill in the region of seasonal frozen soil is affected by freeze-thaw cycle and its physics. The hydrological and mechanical properties have changed, and under the action of long-term heavy load, some typical diseases, such as thawing and thawing, have inevitably occurred, which has reduced the road performance and service life of the roads, thus restricting the healthy and orderly development of the local economy. And spent a lot of manpower and financial resources to repair. In order to clarify the process and mechanism of roadbed disease under heavy vehicle load in seasonal frozen soil region, to deepen the understanding of mechanical properties of compacted silty clay after freeze-thaw cycle, and to provide data support for further research work. In this paper, unconsolidated and undrained static triaxial test and resonance column test are used to test the mechanical properties of compacted silty clay after freeze-thaw cycle. The main works are as follows:. In this paper, the temperature and moisture content of the samples in the freeze-thaw cycle are monitored, the changing law is analyzed, and the time and temperature of freezing and melting are determined. The mass and volume of samples during freeze-thaw cycle were measured by using the self-developed measuring instrument and manual measuring method of volume change of geotextile materials, and the variation rules of physical parameters were obtained. (2) the static properties of compacted silty clay after freeze-thaw cycle were tested by strain-controlled static triaxial apparatus, and the influence of confining pressure, compactness, moisture content and times of freeze-thaw cycle on static properties of compacted silty clay was studied. The relationship between principal stress difference and axial strain of compacted silty clay samples is further analyzed, and the failure strength and tangent modulus of different factors are obtained. The influence of cohesive force and angle of internal friction is discussed, and the prediction formulas of failure strength, tangent modulus, cohesion and angle of internal friction are presented by using multivariate nonlinear regression method. The dynamic parameters of compacted silty clay after freeze-thaw cycle were measured by means of resonance column tester, and the effects of confining pressure, compactness, moisture content and times of freeze-thaw cycle on the dynamic properties of the clay were studied. The influence of different factors on dynamic shear modulus and damping ratio of compacted silty clay is obtained. Based on hyperbolic model, the dynamic shear strain region is extended, and the empirical prediction formula of maximum dynamic shear modulus and maximum damping ratio is proposed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1;U414

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