本文選題：基坑開挖 + 支護(hù)結(jié)構(gòu)��； 參考：《海南大學(xué)》2014年碩士論文

【摘要】：在基坑開挖工程中,基坑變形對基坑自身以及周圍環(huán)境都有非常重要的意義,如何準(zhǔn)確預(yù)測基坑在開挖過程中的變形是基坑工程中的重點(diǎn)和難點(diǎn),目前數(shù)值分析是解決這一問題的有效方法。巖土本構(gòu)模型既是巖土塑性力學(xué)的核心,也是數(shù)值模擬的基石。數(shù)值模擬的核心是本構(gòu)模型和模型參數(shù)的選取,本文主要圍繞常用的部分巖土本構(gòu)模型的適用范圍以及參數(shù)的選取等方面進(jìn)行了相關(guān)研究。 本文選取MC模型、MCC模型、HS模型和HSS模型,通過常規(guī)室內(nèi)土工試驗(yàn)和三軸試驗(yàn)確定所取原狀土的本構(gòu)模型參數(shù),結(jié)合基坑工程的勘察報告建立了一套與這四種本構(gòu)模型相適應(yīng)的參數(shù)選取方案,得到了相關(guān)土層的本構(gòu)模型參數(shù)。利用Plaxis有限元程序?qū)庸こ踢M(jìn)行數(shù)值模擬,將四種本構(gòu)模型得到的數(shù)值模擬結(jié)果與實(shí)測結(jié)果對比分析得到以下結(jié)論： (1)土的彈性模量E可取5Es甚至更大；修正劍橋模型的參數(shù)兄和κ,可根據(jù)勘察報告提供的塑性指數(shù)Ip按推導(dǎo)出的公式計(jì)算；固結(jié)模量Eoed可取為Es,割線模量E50可取為2Eoed,卸載再加載模量Eur可取為5E50;小應(yīng)變參數(shù)G0可取為2Eur,數(shù)值模擬結(jié)果受G0影響較大,且G0值越大數(shù)值模擬結(jié)果越接近實(shí)測結(jié)果,γ0.7波動范圍較小,可取為2E-04； (2)MCC模型、HS模型和HSS模型模擬結(jié)果顯示地表沉降表現(xiàn)為凹槽型,符合工程實(shí)際經(jīng)驗(yàn)；圍護(hù)樁變形表現(xiàn)為腹部向基坑內(nèi)突出呈拋物線形,最大側(cè)移發(fā)生在基坑開挖面附近。 (3)總體模擬效果最理想的是HSS模型,其次是HS模型和MCC模型,MC模型模擬效果不太理想。建議在基坑工程的有限元分析中應(yīng)優(yōu)先選用能夠反映土體剪切硬化、壓縮硬化、能夠區(qū)分加荷和卸荷的剛度差異以及土體小應(yīng)變特性的本構(gòu)模型。建議�？诘貐^(qū)采用HSS模型對基坑工程進(jìn)行數(shù)值分析。 (4)對參數(shù)的選取進(jìn)行優(yōu)化,采用優(yōu)化后的HSS模型參數(shù)得到的圍護(hù)樁變形曲線與實(shí)測結(jié)果更為接近,變化趨勢和數(shù)值都更接近實(shí)測結(jié)果。HSS模型的參數(shù)優(yōu)化可適當(dāng)加大剛度參數(shù)和參考剪切模量的取值。
[Abstract]:In the excavation of foundation pit, the deformation of foundation pit is very important to the foundation pit itself and the surrounding environment. How to accurately predict the deformation of foundation pit in the excavation process is the key and difficult point in the foundation pit engineering. At present, numerical analysis is an effective method to solve this problem. Geotechnical constitutive model is not only the core of geotechnical plastic mechanics, but also the cornerstone of numerical simulation. The core of numerical simulation is the selection of constitutive model and model parameters. This paper mainly focuses on the scope of application of some commonly used geotechnical constitutive models and the selection of parameters. In this paper, we select MC model, MCC model, HS model and HSS model, and determine the constitutive model parameters of the undisturbed soil by conventional indoor geotechnical test and triaxial test. Based on the investigation report of foundation pit engineering, a set of parameter selection schemes suitable for these four constitutive models are established, and the constitutive model parameters of related soil layers are obtained. The numerical simulation of foundation pit engineering is carried out by using Plaxis finite element program. The numerical simulation results obtained by the four constitutive models are compared with the measured results and the following conclusions are obtained: (1) the elastic modulus E of the soil should be even greater than that of the 5Es, and the modified parameters of the Cambridge model, brother and 魏, can be calculated according to the derived formula according to the plastic index Ip provided by the survey report. The consolidation modulus (Eoed), the Secant modulus (E50), the unloading modulus (Eur) and the small strain parameter (G0) can be considered as Ess, 2Eoed50, 5E50 and 5E50, respectively, and the numerical simulation results are greatly affected by G0. The larger the value of G _ 0 is, the closer the numerical simulation results are to the measured results, the smaller the fluctuation range of 緯 _ (0.7) is, the desirable is 2E-04. The simulation results of HS model and HSS model show that the surface subsidence is groove type, which is in line with the practical engineering experience, and the deformation of the retaining pile is that the abdominals protrude into the foundation pit with parabola shape, and the maximum lateral displacement occurs near the excavation surface of the foundation pit. (3) the best simulation effect is HSS model, followed by HS model and MCC model. It is suggested that in the finite element analysis of foundation pit engineering, the constitutive model which can reflect the shear hardening, compression hardening, stiffness difference between loading and unloading and the characteristics of small strain of soil should be selected first. It is suggested that HSS model be used for numerical analysis of foundation pit engineering in Haikou area. 4) the parameters are optimized, and the deformation curve of the retaining pile obtained by the optimized parameters of the HSS model is closer to the measured results. The variation trend and value are closer to the measured results. The parameter optimization of the HSS model can increase the stiffness parameter and the reference shear modulus.
【學(xué)位授予單位】：海南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU473.2;TU470

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