饱和粘土地基中粘附强度试验研究

发布时间：2018-01-09 09:26

本文关键词：饱和粘土地基中粘附强度试验研究　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：近年来抗拔基础作为上部结构的锚固形式被广泛应用,在粘土地基结构物起浮或上拔过程中,不可避免要承受粘性底质对基础的粘附作用,且粘附强度决定了抗拔结构物稳定性及吊装设备选择。例如承受上拔荷载的桩基、桶基等,这些基础的抗拔承载力是结构物稳定重要保障;另一方面,在拔桩、沉船打捞等工程中,结构的抗拔承载力是需要克服的阻力。然而,目前对粘附强度还缺乏系统研究,因此有必要对土与结构物间粘附特性进行研究。本文利用自制组合测盘进行了室内粘附力试验,在此基础上通过单体船模型试验及其数值模拟分析取得了如下结论和成果:(1)室内粘附力试验表明:相同含水率下,基础与土体脱离时所对应的土体位移随拉拔速率增加保持不变,基础与土体间的粘附强度随拉拔速率的增加呈“S型曲线”变化;相同拉拔速率下,基础与土体脱离时所对应的土体位移随含水率增加先增大至某一峰值而后逐渐减小,粘附强度随含水率增加呈单峰曲线变化,且峰值点所对应的粘附强度随速率增加而增大,对应的含水率随之而降低。(2)用不排水强度标准化后的粘附强度随含水率增加单调递增,表明土与结构物间的粘附强度与土体黏聚力是有区别的。(3)基于单体船模型试验,建立三维软粘土地基中结构物拉拔计算模型。计算模型采用Mises屈服准则,并考虑土与结构物之间采用粘聚模型。有限元实例分析表明,拉拔过程中孔压变化规律与试验值比较吻合,验证了粘聚模型能较好地反映土与结构物间接触面变形特性。(4)通过有限元实例分析表明:土与结构物间的粘附特性是拉拔过程中土体负孔压发展的重要影响因素,也影响土体对结构物吸附力的大小。
[Abstract]:In recent years, as the foundation of uplift anchor form upper structure is widely used in clay foundation structure floating or uplift process, inevitably bear the viscous bottom on the basis of the adhesion, and the adhesion strength determines the uplift structure and stability of hoisting equipment. For example under pile pulling load, bucket based on these, the foundation uplift capacity is an important guarantee for structure stability; on the other hand, in the pile, salvage and other projects, the structure of anti pulling force is required to overcome the resistance. However, the adhesion strength is still lack of systematic research, it is necessary to study soil structure the adhesion characteristics were measured. The self-made combined disc indoor adhesion test in this paper, on the basis of the tests of single ship model and its numerical simulation analysis yielded the following conclusions and results: (1) the results showed that the adhesion force test: The different moisture content, the soil displacement corresponding to the foundation and the soil detachment remained unchanged with the drawing rate increased, the adhesion strength between the foundation and the soil was "S" curve "with drawing rate increases; the same drawing rate, soil position corresponding to the shift from the foundation and the soil with water content increased to a peak and then decreases gradually with the increase of water content, the adhesion strength is the single peak curve, the peak point and the corresponding adhesion strength increases with the increase of speed, the corresponding moisture content decreased correspondingly. (2) with the adhesion strength of undrained strength normalized with the increase of water content increasing, adhesion strength soil and soil structure between the cohesion is different. (3) single ship model test based on the computing model of three-dimensional structure of soft clay foundation in drawing. Using Mises yield criterion calculation model, and consider Between the soil and structure by using the cohesive model. Finite element analysis shows that the variation of pore pressure and the test results are in agreement with the drawing process, verify the cohesive model can reflect the soil structure contact surface deformation characteristics. (4) through the finite element analysis shows that the adhesion properties of soil and structure the soil is an important factor in the drawing process of negative pore pressure development, also affect the soil on the adsorption force structure size.

【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU442

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