本文選題：下加載面修正劍橋模型　切入點：ABAQUS　出處：《哈爾濱工業(yè)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：通用有限元軟件ABAQUS以其強大的非線性計算功能在巖土工程領(lǐng)域得到了廣泛的應(yīng)用。在其自帶的彈塑性模型中，修正劍橋模型通常用于描述正常固結(jié)土的力學(xué)特性，在理論上比較合理并且在工程上得到了應(yīng)用。然而，修正劍橋模型并不能合理描述超固結(jié)土體的力學(xué)特性。下加載面修正劍橋模型在理論上彌補了這一缺陷，它具有兩個屈服面，通過下加載面位置的變化反映超固結(jié)土的應(yīng)力應(yīng)變特性，可以彌補ABAQUS自帶本構(gòu)模型的不足。本文主要工作及研究內(nèi)容如下： 1、基于下加載面修正劍橋模型的基本理論，推導(dǎo)出其彈塑性本構(gòu)關(guān)系的表達式和二次開發(fā)所需的應(yīng)力應(yīng)變更新公式。利用ABAQUS提供的用戶材料子程序接口UMAT，，采用FORTRAN語言和顯式的向前Euler積分算法針對下加載面修正劍橋模型開發(fā)出了子程序，擴充了ABAQUS軟件的材料庫。 2、利用所編的UMAT子程序?qū)蝹�單元模型進行不同增量加載步數(shù)的排水條件下的三軸壓縮測試，并與ABAQUS自帶的修正劍橋模型進行對比，證明UMAT子程序具有較高的精度和較好的穩(wěn)定性。應(yīng)用子程序?qū)蝹�單元模型模擬不同的圍壓和排水條件的三軸壓縮試驗，并將結(jié)果與用FORTRAN編程計算得到的理論解進行對比，結(jié)果表明子程序能充分反映不同超固結(jié)比、不同排水條件下超固結(jié)土體的性質(zhì)，如應(yīng)變軟化和剪縮、剪脹等，說明了子程序的適用性。 3、在ABAQUS中模擬超固結(jié)土的三軸壓縮試驗和三軸加卸載試驗，下加載面修正劍橋模型的UMAT子程序能更好地描述土體連續(xù)漸進的變形過程，相比于修正劍橋模型有較大的優(yōu)勢。 4、建立多個單元的超固結(jié)土三軸壓縮試驗和地基固結(jié)沉降的模型，分別與試驗數(shù)據(jù)和ABAQUS自帶的修正劍橋模型進行了對比，證明了下加載面修正劍橋模型對于超固結(jié)土的力學(xué)性質(zhì)能進行較為準確的描述，而且適用于超固結(jié)土的地基的固結(jié)沉降問題。
[Abstract]:The universal finite element software ABAQUS has been widely used in geotechnical engineering for its powerful nonlinear computing function. In its own elastic-plastic model, the modified Cambridge model is usually used to describe the mechanical properties of normal consolidated soil. It is reasonable in theory and has been applied in engineering. However, the modified Cambridge model can not reasonably describe the mechanical properties of overconsolidated soil. It has two yield surfaces, which reflect the stress-strain characteristics of the overconsolidated soil by the change of the position of the lower loading surface, which can make up for the deficiency of the constitutive model of ABAQUS. The main work and research contents of this paper are as follows:. 1. Based on the basic theory of modifying Cambridge model with lower loading surface, The expression of the elastoplastic constitutive relation and the stress-strain updating formula for secondary development are derived. Using the user material subroutine interface provided by ABAQUS, the FORTRAN language and the explicit forward Euler integral algorithm are used to solve the problem of the lower loading surface. The modified Cambridge model developed a subroutine, The material library of ABAQUS software is expanded. 2. The UMAT subroutine is used to test the triaxial compression of a single unit model under the drainage condition with different incremental loading steps, and compared with the modified Cambridge model of ABAQUS. It is proved that the UMAT subroutine has higher precision and better stability. A single unit model is used to simulate the triaxial compression test of different confining pressure and drainage conditions, and the results are compared with the theoretical solution obtained by FORTRAN programming. The results show that the subroutine can fully reflect the properties of the overconsolidated soil under different overconsolidation ratios and drainage conditions, such as strain softening and shearing shrinkage, shear expansion, etc., which shows the applicability of the subroutine. 3. By simulating triaxial compression test and triaxial loading and unloading test of overconsolidated soil in ABAQUS, the UMAT subroutine of the lower loading surface modified Cambridge model can better describe the continuous progressive deformation process of soil, which is superior to the modified Cambridge model. 4. The triaxial compression test of overconsolidated soil and the model of foundation consolidation settlement were established, and the results were compared with the test data and the modified Cambridge model brought by ABAQUS. It is proved that the modified Cambridge model of the lower loading surface can accurately describe the mechanical properties of the overconsolidated soil and is suitable for the consolidation and settlement of the foundation of the overconsolidated soil.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU43

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