饱和砂土的三轴试验及地震液化分析研究

发布时间：2018-06-12 01:49

本文选题：饱和砂土 + 三轴试验　；参考：《大连理工大学》2013年硕士论文

【摘要】：防波堤等土工构筑物在地震作用下发生破坏和倒塌,往往给人的生命和财产造成灾难性的损失。其中土体的液化是引起地基失效的主要原因之一,而影响地基砂土液化的因素有很多,现阶段对于砂土地震液化的认识仍具有局限性,饱和砂土地震液化的分析是一个重要的研究课题,也是研究的难点。过去在对饱和砂土地基上防波堤等堤防构筑物的液化分析计算中,主要采用总应力分析方法,一般采用邓肯-张模型用于静力计算,采用等效线性模型分析动力反应,采用液化安全率的方法判别液化。这种计算方法虽然取得了大量的研究成果,但是在计算过程中需要采用不同的模型和参数,计算过程复杂并且结果也不尽合理。而且总应力分析方法忽略了振动孔隙水压力变化对土体动力特性的影响,不能够准确合理地分析动荷载作用下的土体液化。本文饱和砂土的本构模型采用广义塑性模型,该模型基于广义塑性理论框架提出,只需要一组模拟数据就可以完成土工构筑物的静、动力全部分析,并已成功运用于诸多的实际工程。本文采用计算分析方法为有效应力分析方法,此方法相较总应力法而言,提高了计算精度,可以预测动荷载作用过程中孔隙水压力的变化过程和土体液化的可能性。在国家自然科学基金重点项目“地震作用下核电厂工程结构的功能失效机理及抗震安全评价(51138001)”、辽宁省自然科学基金“复杂海洋地基条件下核电厂取排水盾构隧洞地震响应研究(201102026)”、地震行业科研专项经费项目“核电厂取排水构筑物地震响应特征和破坏机理研究(201208013)”的支持下,开展了如下工作： (1)采用TSZ-6A型应变三轴仪和DS-2T型振动三轴仪,对两种不同密度的饱和砂土进行三轴静、动力剪切试验,并对试验结果进行了分析。 (2)根据试验结果拟合出砂土的广义塑性模型参数,对比分析试验结果与模型拟合结果的差异,验证所用模型的可靠性。 (3)通过基于饱和土动力固结理论的有效应力分析方法,对砂土地基上的核电厂取排水工程防波堤进行弹塑性分析,研究其在地震条件下的液化可能性,并通过对比不同计算工况孔隙水压力和孔压比的不同,分析说明采取换填式和反压式两种措施对地基液化的改善。
[Abstract]:Soil structures such as breakwaters are destroyed and collapsed under earthquake, which often result in catastrophic loss of human life and property. Among them, the liquefaction of soil is one of the main causes of foundation failure, and there are many factors that affect the liquefaction of foundation sand. At present, the knowledge of seismic liquefaction of sand is still limited. The analysis of seismic liquefaction of saturated sand is an important research subject and a difficult point. In the past, the total stress analysis method was mainly used in the liquefaction analysis of levees such as breakwaters on saturated sand foundation. The Duncan-Chang model is generally used for static calculation, the equivalent linear model is used to analyze the dynamic reaction, and the method of safe rate of liquefaction is used to judge liquefaction. Although this method has obtained a lot of research results, it needs different models and parameters in the calculation process, and the calculation process is complex and the results are not reasonable. Moreover, the total stress analysis method neglects the influence of the vibration pore water pressure change on the dynamic characteristics of soil, and can not accurately and reasonably analyze the soil liquefaction under dynamic load. The constitutive model of saturated sand is generalized plastic model. Based on the generalized plastic theory framework, the model can be used to analyze the static and dynamic properties of geotechnical structures, and has been successfully applied to many practical projects. In this paper, the method of calculation and analysis is used as the effective stress analysis method. Compared with the total stress method, this method improves the accuracy of calculation. The variation process of pore water pressure and the possibility of soil liquefaction during dynamic loading can be predicted. Liaoning Provincial Natural Science Foundation, "Seismic response Research of Shield Tunnel for Nuclear Power Plant drainage under complex Ocean Foundation conditions (201102026)", Supported by the special research project of earthquake industry, "study on seismic response characteristics and failure mechanism of drainage structures in nuclear power plants (201208013)", the following works have been carried out: 1) using TSZ-6A strain triaxial instrument and DS-2T vibration triaxial instrument, Two kinds of saturated sand with different density were tested by triaxial static and dynamic shear tests, and the test results were analyzed. According to the test results, the parameters of generalized plastic model of sand were fitted, and the difference between the test results and the model fitting results was analyzed. To verify the reliability of the model used in this paper, the effective stress analysis method based on the dynamic consolidation theory of saturated soil is used to analyze the breakwater of a nuclear power plant on sand foundation, and the possibility of liquefaction under seismic conditions is studied. By comparing the difference of pore water pressure and pore pressure ratio in different calculation conditions, the improvement of foundation liquefaction by adopting two kinds of measures, the replacement type and the back pressure type, is analyzed.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TV223;TU441

【参考文献】