本文關(guān)鍵詞： 軟土沉降 側(cè)向變形 e-p曲線 切線模量 分層總和法　出處：《華南理工大學(xué)》2014年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：隨著社會(huì)的發(fā)展，越來(lái)越多的建筑物、構(gòu)造物不得不建筑于軟土地基上，這使得軟土地基處理中最核心的兩個(gè)問(wèn)題越來(lái)越突出：沉降和穩(wěn)定。然而，由于軟土地基的高壓縮性、高孔隙比、高含水量、低滲透性、低強(qiáng)度、觸變性以及蠕變性等工程特性，軟土地基的沉降計(jì)算準(zhǔn)確性很低。因此尋求一個(gè)簡(jiǎn)便實(shí)用的新的沉降計(jì)算方法使其計(jì)算精度能滿足工程需要是非常必要的。 目前，依據(jù)我國(guó)的地基規(guī)范，，軟土地基的沉降主要是采用側(cè)限壓縮試驗(yàn)曲線進(jìn)行一維壓縮沉降計(jì)算，再對(duì)該計(jì)算結(jié)果乘以一個(gè)經(jīng)驗(yàn)修正系數(shù)而得到的。該修正系數(shù)用來(lái)反映軟土側(cè)向變形所產(chǎn)生的沉降，取值范圍為1.1~1.7，該范圍變化較大，且缺乏量化取用依據(jù)。因此，側(cè)向變形引起的沉降尚缺乏可靠有效的實(shí)用計(jì)算方法，而這部分沉降又是不可忽略的。 本文將軟土地基的沉降分為有側(cè)限的壓縮沉降和無(wú)側(cè)限條件下剪應(yīng)力引起的側(cè)向變形而產(chǎn)生的沉降兩部分。有側(cè)限的壓縮沉降采用傳統(tǒng)的e-p曲線分層總和法計(jì)算得到；側(cè)向變形產(chǎn)生的沉降采用以非線性切線模量Et用分層總和法計(jì)算得到。 對(duì)非線性切線模量Et，本文基于e-p曲線和鄧肯-張（Duncan-Chang）本構(gòu)模型的概念，提出了用e-p曲線計(jì)算軟土的非線性切線模量Et的方法。采用地基的安全系數(shù)法確定破壞比，用于修正由于采用彈性應(yīng)力解產(chǎn)生的不合理應(yīng)力水平。采用由地基整體固結(jié)度確定得到的總應(yīng)力強(qiáng)度指標(biāo)計(jì)算應(yīng)力水平，進(jìn)而計(jì)算得到切線模量，即可反映加荷速率和荷載大小對(duì)剪切沉降的影響。 用本文建立的軟土地基非線性沉降計(jì)算實(shí)用計(jì)算方法對(duì)兩個(gè)案例的地基沉降進(jìn)行計(jì)算；將結(jié)果與實(shí)測(cè)數(shù)據(jù)、規(guī)范方法計(jì)算結(jié)果和有限元數(shù)值分析結(jié)果進(jìn)行比較分析，計(jì)算效果良好，驗(yàn)證了方法的可行性和優(yōu)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.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TU433;TU447

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