基于e-p曲线的软土地基非线性沉降实用计算方法研究

发布时间：2018-02-20 23:56

本文关键词： 软土沉降侧向变形 e-p曲线切线模量分层总和法　出处：《华南理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着社会的发展，越来越多的建筑物、构造物不得不建筑于软土地基上，这使得软土地基处理中最核心的两个问题越来越突出：沉降和稳定。然而，由于软土地基的高压缩性、高孔隙比、高含水量、低渗透性、低强度、触变性以及蠕变性等工程特性，软土地基的沉降计算准确性很低。因此寻求一个简便实用的新的沉降计算方法使其计算精度能满足工程需要是非常必要的。目前，依据我国的地基规范，，软土地基的沉降主要是采用侧限压缩试验曲线进行一维压缩沉降计算，再对该计算结果乘以一个经验修正系数而得到的。该修正系数用来反映软土侧向变形所产生的沉降，取值范围为1.1~1.7，该范围变化较大，且缺乏量化取用依据。因此，侧向变形引起的沉降尚缺乏可靠有效的实用计算方法，而这部分沉降又是不可忽略的。本文将软土地基的沉降分为有侧限的压缩沉降和无侧限条件下剪应力引起的侧向变形而产生的沉降两部分。有侧限的压缩沉降采用传统的e-p曲线分层总和法计算得到；侧向变形产生的沉降采用以非线性切线模量Et用分层总和法计算得到。对非线性切线模量Et，本文基于e-p曲线和邓肯-张（Duncan-Chang）本构模型的概念，提出了用e-p曲线计算软土的非线性切线模量Et的方法。采用地基的安全系数法确定破坏比，用于修正由于采用弹性应力解产生的不合理应力水平。采用由地基整体固结度确定得到的总应力强度指标计算应力水平，进而计算得到切线模量，即可反映加荷速率和荷载大小对剪切沉降的影响。用本文建立的软土地基非线性沉降计算实用计算方法对两个案例的地基沉降进行计算；将结果与实测数据、规范方法计算结果和有限元数值分析结果进行比较分析，计算效果良好，验证了方法的可行性和优越性。
[Abstract]:With the development of society, more and more buildings and structures have to be built on soft foundation, which makes the two core problems in soft foundation treatment more and more prominent: settlement and stability. However, due to the high compressibility of soft foundation, Engineering properties such as high void ratio, high water content, low permeability, low strength, thixotropy and creep, etc. The accuracy of settlement calculation of soft soil foundation is very low, so it is very necessary to seek a simple and practical new settlement calculation method so that its calculation accuracy can meet the engineering needs. At present, according to the foundation code of our country, the settlement of soft soil foundation is mainly calculated by using the lateral limit compression test curve to calculate the one-dimensional compression settlement. The calculated result is multiplied by an empirical correction coefficient. The correction coefficient is used to reflect the settlement caused by lateral deformation of soft soil, with a range of 1.1 ~ 1.7, which varies greatly and lacks the basis of quantification. The settlement caused by lateral deformation is still lack of reliable and effective calculation method, and this part of settlement can not be ignored. In this paper, the settlement of soft soil foundation is divided into two parts: the compression settlement with lateral limit and the settlement caused by shear stress under the condition of no lateral limit. The compression settlement with side limit is calculated by traditional e-p curve stratified summation method. The settlement caused by lateral deformation is calculated by means of nonlinear tangent modulus et and stratified summation method. Based on the concept of e-p curve and Duncan Zhang Duncan-Chang-constitutive model, a method of calculating nonlinear tangent modulus E _ t of soft soil by e-p curve is presented in this paper, and the failure ratio is determined by the method of safety factor of foundation. It is used to correct the unreasonable stress level caused by the elastic stress solution. The total stress intensity index determined from the consolidation degree of the foundation is used to calculate the stress level, and then the tangent modulus is calculated. The effect of loading rate and load size on shear settlement can be reflected. Using the practical calculation method of nonlinear settlement of soft soil foundation established in this paper, the foundation settlement of two cases is calculated, and the results are compared with the measured data, the calculated results of the standard method and the results of finite element numerical analysis. The result of calculation is good, and the feasibility and superiority of the method are verified.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU433;TU447

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