本文選題：飽和砂土 + 三軸試驗　； 參考：《大連理工大學》2013年碩士論文

【摘要】：防波堤等土工構筑物在地震作用下發(fā)生破壞和倒塌,往往給人的生命和財產造成災難性的損失。其中土體的液化是引起地基失效的主要原因之一,而影響地基砂土液化的因素有很多,現(xiàn)階段對于砂土地震液化的認識仍具有局限性,飽和砂土地震液化的分析是一個重要的研究課題,也是研究的難點。 過去在對飽和砂土地基上防波堤等堤防構筑物的液化分析計算中,主要采用總應力分析方法,一般采用鄧肯-張模型用于靜力計算,采用等效線性模型分析動力反應,采用液化安全率的方法判別液化。這種計算方法雖然取得了大量的研究成果,但是在計算過程中需要采用不同的模型和參數(shù),計算過程復雜并且結果也不盡合理。而且總應力分析方法忽略了振動孔隙水壓力變化對土體動力特性的影響,不能夠準確合理地分析動荷載作用下的土體液化。 本文飽和砂土的本構模型采用廣義塑性模型,該模型基于廣義塑性理論框架提出,只需要一組模擬數(shù)據(jù)就可以完成土工構筑物的靜、動力全部分析,并已成功運用于諸多的實際工程。本文采用計算分析方法為有效應力分析方法,此方法相較總應力法而言,提高了計算精度,可以預測動荷載作用過程中孔隙水壓力的變化過程和土體液化的可能性。 在國家自然科學基金重點項目“地震作用下核電廠工程結構的功能失效機理及抗震安全評價(51138001)”、遼寧省自然科學基金“復雜海洋地基條件下核電廠取排水盾構隧洞地震響應研究(201102026)”、地震行業(yè)科研專項經費項目“核電廠取排水構筑物地震響應特征和破壞機理研究(201208013)”的支持下,開展了如下工作： (1)采用TSZ-6A型應變三軸儀和DS-2T型振動三軸儀,對兩種不同密度的飽和砂土進行三軸靜、動力剪切試驗,并對試驗結果進行了分析。 (2)根據(jù)試驗結果擬合出砂土的廣義塑性模型參數(shù),對比分析試驗結果與模型擬合結果的差異,驗證所用模型的可靠性。 (3)通過基于飽和土動力固結理論的有效應力分析方法,對砂土地基上的核電廠取排水工程防波堤進行彈塑性分析,研究其在地震條件下的液化可能性,并通過對比不同計算工況孔隙水壓力和孔壓比的不同,分析說明采取換填式和反壓式兩種措施對地基液化的改善。
[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.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TV223;TU441

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