【作者】 黄全强；

【导师】 陆培毅；

【作者基本信息】 天津大学 ， 结构工程， 2009， 硕士

【摘要】 本文以天津滨海新区饱和软粘土为研究对象,按照Seed的转化方法将地震荷载转化为等效循环荷载,通过GDS动三轴系统对其进行单向激振循环荷载试验。文章主要研究了振动频率、循环应力比、固结围压等因素对地震荷载作用下滨海新区饱和软粘土动强度和变形特性的影响,并得出了一些对工程实践有意义的结论。1.试验表明饱和软粘土存在着临界循环应力比,当循环应力比小于临界值时很难发生破坏,当大于临界值时在很少的循环振次内就达到了破坏。随着循环振动次数的增加,软土的累积变形逐渐增大,动强度则逐渐降低。2.在地震荷载的作用下,滨海新区饱和软粘土的强度急剧下降,其内摩擦角仅为原来的35%左右;对原状土和加固土的对比研究表明,软土地基经过加固处理后,其动强度和承载力都得到了较大的提高。3.对试验数据进行分析拟合,提出了基于试验基础的适合于滨海新区软粘土的动孔压计算模型。4.根据试验结果,提出了滨海新区饱和软粘土在地震荷载作用下的动承载力计算公式和沉降变形计算公式。文中重点研究了软土的变形特性,并结合一震陷实例进行了对比分析。通过计算结果和实测数据的对比分析表明,计算值和实测值吻合的较好。最后,本文对研究的工作进行了总结,并指出了尚未研究的课题或者研究中存在的一些问题,为进一步研究提供一定的理论依据和参考作用。更多还原

【Abstract】 The saturated soft clays in the Binhai New Area is studied in this paper, and by the method of Seed the seismic loading is converted into the equivalent cyclic loading, and the effect of the vibration frequency, cyclic stress ratio and consolidation pressure on the dynamic strength and deformation characteristics of the soft clay under the seismic loading is studied based on the unidirectional cyclic loading test in the use of the GDS dynamic triaxial system, then some important conclusions are obtained.1. The study shows that there is a critical cyclic stress ratio in the saturated soft clays. When the cyclic stress ratio is less than the critical value, it is difficult for the soft clay to break, or else it is easy to break in a few cycles. With the increase in the number of cycle of vibration, the cumulative deformation increases, while the strength reduces gradually.2. Under the action of seismic loading, the strength of saturated soft clay in Binhai New Area decreased sharply and its internal friction angle was only about 35% of the original angle. By studying on undisturbed soil and reinforced soil, the results show that the dynamic strength and bearing capacity of soft foundation have been greatly improved after the soft clay reinforced.3. Through analyzing the experimental data, a dynamic pore pressure calculation model that was suitable for the saturated soft clay in Binhai New Area was proposed in the paper.4. Based on the test results, a formula for calculating cyclic carrying capacity and settlement deformation of the saturated soft clay in Binhai New Area was proposed under the seismic loading. The deformation characteristics of soft clay were focused on, and then a project of seismic subsidence was taken for example. By comparing the calculations with measured data, the result showed that the calculated value matched the actual value well.In the end, the research work was summed up in the paper and some issues on the research were pointed out, which would provide a theoretical basis and reference for further research.更多还原