【摘要】：基坑開挖一般是建筑物建設(shè)的第一階段,對建筑物的穩(wěn)定,鄰近建筑物、基礎(chǔ)設(shè)施的穩(wěn)定也有著重要的影響,分析好基坑開挖的變形意義重大。目前應用最廣、效果較好的是數(shù)值模擬計算方法。但數(shù)值分析方法中存在選取合適的本構(gòu)模型這一問題,通過本文數(shù)值模擬發(fā)現(xiàn),不同的本構(gòu)模型得出的計算結(jié)果相差很大。本文利用數(shù)值計算軟件PLAXIS 3D來模擬實際工程基坑開挖,重點說明了各種本構(gòu)模型的理論基礎(chǔ)和適用范圍,得出在反映基坑開挖變形方面小應變本構(gòu)模型有著一定的優(yōu)勢的結(jié)論。主要包含以下三個方面的內(nèi)容:(1)全方位介紹了基坑開挖的變形模式及變形預測方法;比較了不同土體本構(gòu)模型的理論基礎(chǔ)、適用范圍、優(yōu)缺點,重點介紹了小應變本構(gòu)模型。(2)介紹了數(shù)值分析軟件PLAXIS 3D,利用PLAXIS 3D軟件自帶的小應變本構(gòu)模型分析了基坑開挖預留反壓土對基坑變形的影響。主要利用控制變量法,控制預留反壓土的剖面形狀、自身重量,對比不同情形下基坑開挖的變形。并將反壓土重量分別增大10%和20%,增大的重量用于提高預留反壓土臺的穩(wěn)定,具體措施是分別使其預留寬度和高度最大化、角度最小化,分析此時基坑變形,結(jié)果表明減小反壓土的坡度對基坑穩(wěn)定最好。(3)給出了得到小應變本構(gòu)模型(HSS)參數(shù)的試驗方法及參數(shù)意義,結(jié)合某工程實例,利用其實測數(shù)據(jù)與小應變本構(gòu)模型和硬化土本構(gòu)模型計算結(jié)果比對,也驗證了小應變本構(gòu)模型在模擬實際工程基坑開挖方面的優(yōu)越性。
[Abstract]:Excavation of foundation pit is generally the first stage of building construction, which has an important influence on the stability of buildings, adjacent buildings and infrastructure facilities, and it is of great significance to analyze the deformation of excavation. At present, numerical simulation method is the most widely used and effective method. However, there is a problem of choosing suitable constitutive model in the numerical analysis method. Through the numerical simulation in this paper, it is found that the calculation results of different constitutive models are very different. In this paper, the numerical calculation software PLAXIS 3D is used to simulate the excavation of practical engineering foundation pit. The theoretical basis and applicable range of various constitutive models are explained, and the conclusion is drawn that the small strain constitutive model has some advantages in reflecting the deformation of foundation pit excavation. It mainly includes the following three aspects: (1) the deformation mode and deformation prediction method of excavation are introduced in all directions; The theoretical basis, application scope, advantages and disadvantages of different soil constitutive models are compared, and the small strain constitutive models are emphatically introduced. (2) the numerical analysis software PLAXIS 3D is introduced. In this paper, the small strain constitutive model of PLAXIS 3D software is used to analyze the influence of pre-pressure soil on the deformation of foundation pit. The control variable method is mainly used to control the profile shape and weight of the reserved backpressure soil and to compare the deformation of foundation pit excavation under different conditions. The weight of the backpressure soil is increased by 10% and 20% respectively, and the increased weight is used to improve the stability of the reserved backpressure soil platform. The concrete measures are to maximize the reserved width and height, minimize the angle, and analyze the deformation of foundation pit. The results show that the stability of foundation pit is best to reduce the slope of backpressure soil. (3) the test method and parameter significance of (HSS) parameters of small strain constitutive model are given. The comparison of the measured data with the calculation results of the small strain constitutive model and the hardening soil constitutive model also verifies the superiority of the small strain constitutive model in simulating the excavation of practical engineering foundation pit.
【學位授予單位】：天津大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU753

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