【作者】 陈磊；

【导师】 郑刚；

【作者基本信息】 天津大学 ， 结构工程， 2014， 硕士

【摘要】 基坑开挖一般是建筑物建设的第一阶段,对建筑物的稳定,邻近建筑物、基础设施的稳定也有着重要的影响,分析好基坑开挖的变形意义重大。目前应用最广、效果较好的是数值模拟计算方法。但数值分析方法中存在选取合适的本构模型这一问题,通过本文数值模拟发现,不同的本构模型得出的计算结果相差很大。本文利用数值计算软件PLAXIS 3D来模拟实际工程基坑开挖,重点说明了各种本构模型的理论基础和适用范围,得出在反映基坑开挖变形方面小应变本构模型有着一定的优势的结论。主要包含以下三个方面的内容:(1)全方位介绍了基坑开挖的变形模式及变形预测方法;比较了不同土体本构模型的理论基础、适用范围、优缺点,重点介绍了小应变本构模型。(2)介绍了数值分析软件PLAXIS 3D,利用PLAXIS 3D软件自带的小应变本构模型分析了基坑开挖预留反压土对基坑变形的影响。主要利用控制变量法,控制预留反压土的剖面形状、自身重量,对比不同情形下基坑开挖的变形。并将反压土重量分别增大10%和20%,增大的重量用于提高预留反压土台的稳定,具体措施是分别使其预留宽度和高度最大化、角度最小化,分析此时基坑变形,结果表明减小反压土的坡度对基坑稳定最好。(3)给出了得到小应变本构模型(HSS)参数的试验方法及参数意义,结合某工程实例,利用其实测数据与小应变本构模型和硬化土本构模型计算结果比对,也验证了小应变本构模型在模拟实际工程基坑开挖方面的优越性。更多还原

【Abstract】 The first stage of building is normally excavation. The deformation analysis of excavation is very important that it has huge influence in nearby building and infrastructure. Now the method which applies widely and has good effect is numerical analysis, but Numerical analysis need choose a suitable Constitutive Model. According to numerical simulation, the results with different constitutive numerical had great disparity. This paper uses numerical analysis software PLAXIS 3D to analyze excavation, introduces different constitutive model, and concludes that Hardening Soil Small(HSS)constitutive model has some advantage in deformation of foundation pit. The main content includes three aspects:First, introduce the deformation models and predication methods of excavation overall. Compare different earth constitutive models and introduce HSS constitutive model in detail.Second, introduce numerical analysis software PLAXIS 3D and use it to analyze the deformation of excavation with earth berm. Controlling the earth berms’ shape and weight, compare the different deformations of foundation pit in distinct situations. Improved ten percents and twenty percents earth of berm’s weight to strengthen foundation pit. The method was maximizing the earth berm’s width and height and minimizing the earth berm’s angle. The result presented that minimizing angle is better.Third, show the test way to get HSS’s parameters and the parameters’ meanings. Combined a real excavation with numerical analysis, comparing the real monitor data and numerical data of HSS model and Hardening Soil model, verifying HSS’s advantage in excavation’s numerical simulation.更多还原