本文選題：蠕變 + Merchant模型��； 參考：《天津大學(xué)》2014年碩士論文

【摘要】：蠕變是巖土材料重要的性質(zhì),軟黏土的蠕變特性對工程結(jié)構(gòu)的穩(wěn)定和變形有著至關(guān)重要的影響,成為工程建設(shè)中需要考慮的重要問題之一。巖土蠕變模型種類復(fù)雜,參數(shù)繁多,蠕變模型及其參數(shù)辨識成為工程應(yīng)用中亟需解決的問題。由于室內(nèi)蠕變實驗會耗費大量的人力、物力以及時間,實際操作中存在較多的困難,且土體蠕變試驗并沒有完整明確的土工試驗規(guī)程,蠕變試驗結(jié)果隨意性較強。本文結(jié)合天津地區(qū)軟黏土蠕變試驗結(jié)果,采用回歸擬合的方法確定適宜的本構(gòu)模型及其參數(shù),并用數(shù)值計算軟件證明了擬合的正確性。大型的軟土基坑一般開挖面積較大,從工期,造價和施工難度上往往難以施加對撐。根據(jù)最近的工程實例,開始采用基坑周邊圍護(hù)范圍預(yù)留反壓土的方案,可取的良好的經(jīng)濟效益。以往的反壓土研究多集中于對圍護(hù)結(jié)構(gòu)的作用,并沒有關(guān)注軟黏土蠕變特性對反壓土“圍護(hù)體系”的影響機理。本文通過有限元計算探究分析了軟黏土蠕變特性對于圍護(hù)結(jié)構(gòu)及基坑穩(wěn)定變形的影響。深大基坑反壓土開挖施工過程中,受到各種施工參數(shù)的影響,本文通過有限元分析軟件建立了基本算例,分析了反壓土截面性狀、土體本構(gòu)模型、基坑開挖速度、地下水滲流、土體應(yīng)力歷史等因素對反壓土體系時間效應(yīng)的影響,探究了反壓土的時間效應(yīng)機理,以期指導(dǎo)工程實踐。最后結(jié)合天津嘉海一期實際工程建立有限元計算模型,探討了反壓土無支撐體系的時間效應(yīng)。進(jìn)一步證實了軟黏土地區(qū)深大基坑施工過程中反壓土體系的時間效應(yīng),分析了無支撐期間圍護(hù)結(jié)構(gòu)及基坑的受力及變形特征,揭示了基坑開挖反壓土?xí)r間效應(yīng)機理。
[Abstract]:Creep is an important property of geotechnical materials. The creep characteristics of soft clay have a vital effect on the stability and deformation of engineering structures, and become one of the important problems to be considered in engineering construction. The creep model of rock and soil is complicated and has a variety of parameters. The creep model and its parameter identification have become an urgent problem to be solved in engineering application. Because the indoor creep test will consume a lot of manpower, material resources and time, there are many difficulties in the actual operation, and there is no complete and definite geotechnical test rules for the creep test of soil, and the creep test results are random. Based on the creep test results of soft clay in Tianjin area, the suitable constitutive model and its parameters are determined by regression fitting method, and the correctness of the fitting is proved by numerical calculation software. The excavation area of large soft soil foundation pit is generally large, so it is difficult to apply bracing in terms of time limit, cost and construction difficulty. According to the recent engineering examples, the scheme of reserving backpressure soil in the surrounding retaining area of foundation pit is adopted, which is desirable for good economic benefit. In the past, the research of backpressure soil focused on the effect of the retaining structure, and did not pay attention to the influence mechanism of the creep characteristics of soft clay on the "envelope system" of the backpressure soil. In this paper, the influence of creep characteristics of soft clay on the stable deformation of retaining structure and foundation pit is analyzed by finite element method. During the excavation of deep and large foundation pit, it is affected by various construction parameters. In this paper, a basic example is established by means of finite element analysis software, and the cross section behavior of backpressure soil, constitutive model of soil, excavation speed of foundation pit and seepage of groundwater are analyzed. The influence of soil stress history and other factors on the time effect of backcompacted soil system is discussed, and the time effect mechanism of backcompacted soil is explored in order to guide engineering practice. Finally, the finite element model is established for the first stage of Tianjin Jia-hai Project, and the time effect of the unbraced soil system is discussed. The time effect of the backpressure soil system during the construction of deep and large foundation pit in soft clay area is further confirmed. The stress and deformation characteristics of the retaining structure and foundation pit during the period of no support are analyzed, and the mechanism of the time effect of the backpressure soil in the excavation of the foundation pit is revealed.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU753

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