本文選題：黃土 + 結(jié)構(gòu)性��； 參考：《西北農(nóng)林科技大學(xué)》2014年博士論文

【摘要】：黃土是一種典型的結(jié)構(gòu)性土，在我國(guó)有著廣泛的分布，且多集中在烈度高地震多發(fā)的中西部地區(qū)。黃土的結(jié)構(gòu)性直接影響其力學(xué)性質(zhì)，是引起黃土地區(qū)環(huán)境災(zāi)害和工程問(wèn)題的主要原因之一。本文總結(jié)了土結(jié)構(gòu)性研究的基本途徑和發(fā)展階段，選擇土力學(xué)研究方法研究土的結(jié)構(gòu)性。通過(guò)分析土體結(jié)構(gòu)在受力過(guò)程中的變化機(jī)理，分別構(gòu)建靜、動(dòng)荷載條件下黃土結(jié)構(gòu)性的單變量參數(shù)。該組單變量參數(shù)既繼承了前人成果的合理內(nèi)核，又拓展了結(jié)構(gòu)性參數(shù)的應(yīng)用空間，此外還具有簡(jiǎn)化計(jì)算過(guò)程，利于實(shí)現(xiàn)數(shù)值計(jì)算等優(yōu)點(diǎn)。所獲得的成果如下： 1．本文在深入分析前人提出的基于變形考慮的結(jié)構(gòu)性定量化參數(shù)和基于強(qiáng)度考慮的結(jié)構(gòu)性定量化參數(shù)的基礎(chǔ)之上，提出了兩者在形式上統(tǒng)一的表達(dá)式—即采用割線(xiàn)模量表示的土結(jié)構(gòu)性參數(shù)。采用割線(xiàn)模量表示的土結(jié)構(gòu)性參數(shù)的積極意義在于避免由于起始狀態(tài)土的應(yīng)力、應(yīng)變都是零時(shí)基于應(yīng)力考慮的和基于應(yīng)變考慮的土結(jié)構(gòu)性參數(shù)無(wú)初始解現(xiàn)象。 2．構(gòu)建了以主動(dòng)作用為單變量描述的土結(jié)構(gòu)性單變量參數(shù)，分別為側(cè)限壓縮試驗(yàn)條件下的基于相同壓力方法和基于相同變形方法的土結(jié)構(gòu)性單變量參數(shù)，以及三軸試驗(yàn)條件下的基于相同主應(yīng)力差方法和基于相同大主應(yīng)變方法的土結(jié)構(gòu)性單變量參數(shù)。所構(gòu)建的結(jié)構(gòu)性單變量參數(shù)具有的積極意義在于由于涉及的單變量是主動(dòng)作用，所以該結(jié)構(gòu)性參數(shù)可以直觀地反映主動(dòng)作用對(duì)土結(jié)構(gòu)性的影響。 3．分別對(duì)側(cè)限壓縮試驗(yàn)條件下和三軸試驗(yàn)條件下的黃土結(jié)構(gòu)性單變量參數(shù)進(jìn)行檢驗(yàn)。檢驗(yàn)的結(jié)果表明所建議的黃土結(jié)構(gòu)性單變量參數(shù)計(jì)算的結(jié)果能夠和與原始公式計(jì)算結(jié)果較好地吻合，說(shuō)明所建議的結(jié)構(gòu)性單變量參數(shù)具有合理性。通過(guò)對(duì)不同地區(qū)黃土的原狀樣、重塑樣和人工結(jié)構(gòu)性樣進(jìn)行側(cè)限壓縮試驗(yàn)和三軸壓縮試驗(yàn)，研究黃土結(jié)構(gòu)性的變化規(guī)律。對(duì)相關(guān)影響因素展開(kāi)分析，獲取不同試驗(yàn)條件下結(jié)構(gòu)性參數(shù)曲線(xiàn)的特征。同時(shí)，，試驗(yàn)結(jié)果還發(fā)現(xiàn)基于相同壓力(主應(yīng)力差)方法的黃土結(jié)構(gòu)性參數(shù)和基于變形(大主應(yīng)變)方法的黃土結(jié)構(gòu)性參數(shù)除了主動(dòng)作用起始點(diǎn)處相等外，其余的并不相等。因此，需在使用時(shí)注明是基于何種方法的黃土結(jié)構(gòu)性參數(shù)。 4．分別構(gòu)建了動(dòng)荷載試驗(yàn)條件下黃土結(jié)構(gòu)性單變量參數(shù)，即基于相同動(dòng)剪應(yīng)力方法和基于相同動(dòng)剪應(yīng)變方法的黃土動(dòng)結(jié)構(gòu)性單變量參數(shù)。對(duì)蘭州、洛川、楊凌三個(gè)地區(qū)黃土進(jìn)行了動(dòng)扭剪三軸試驗(yàn)。在獲得蘭州、洛川、楊凌三個(gè)地區(qū)黃土動(dòng)剪應(yīng)力與動(dòng)剪應(yīng)變關(guān)系曲線(xiàn)的基礎(chǔ)上，利用所構(gòu)建的土動(dòng)結(jié)構(gòu)性的單變量參數(shù)對(duì)試驗(yàn)數(shù)據(jù)進(jìn)行整理。檢驗(yàn)了動(dòng)荷載試驗(yàn)條件下黃土動(dòng)結(jié)構(gòu)性單變量參數(shù)的合理性，并且得到了蘭州、洛川、楊凌這三個(gè)地區(qū)基于相同動(dòng)剪應(yīng)力方法的黃土動(dòng)結(jié)構(gòu)性單變量參數(shù)曲線(xiàn)和基于相同動(dòng)剪應(yīng)變方法的黃土動(dòng)結(jié)構(gòu)性單變量參數(shù)曲線(xiàn)，分析動(dòng)力條件下黃土動(dòng)結(jié)構(gòu)性變化規(guī)律，及該特性在不同地區(qū)的差異。
[Abstract]:Loess is a typical structural soil, which is widely distributed in our country and concentrated in the central and western regions with high intensity and high earthquake. The structure of loess directly affects its mechanical properties, which is one of the main reasons causing environmental disasters and engineering problems in the loess region. This paper has always been the basic approach to the study of soil structure and the development order. The single variable parameters of loess structure under static and dynamic loading conditions are constructed by analyzing the change mechanism of soil structure in the stress process. The single variable parameters of this group not only inherit the reasonable kernel of the previous achievements, but also expand the application space of the structural parameters, in addition, it also has the application space of the structural parameters. The advantages of simplifying the calculation process and realizing numerical calculation are as follows.
1. in this paper, based on the in-depth analysis of the structural quantitative parameters based on deformation considerations and the structural quantitative parameters based on the strength consideration, this paper proposes a unified expression in the form of the soil structural parameters represented by the secant modulus. The extreme significance is to avoid the initial solution of soil structural parameters based on stress and strain considering the stress in the initial state.
2. the single variable parameters of soil structure based on the active action as a single variable are constructed, which are the single variable parameters based on the same pressure method and the same deformation method based on the lateral compression test, and the soil based on the same principal stress difference method and the same large principal strain method under the three axis test condition. Structural univariate parameters. The positive significance of the structural single variable parameters is that the structural parameters can directly reflect the effect of the active effect on the soil structure because the involved univariate is active.
3. the structural univariate parameters of loess under the condition of lateral compression test and three axis test are tested respectively. The results show that the calculated results of the proposed structural single variable parameters can be in good agreement with the original formula, indicating that the proposed structural parameters are reasonable. Through the lateral compression test and three axis compression test of the original samples, remolded samples and artificial structural samples in different regions, the changes in the structural changes of loess are studied. The related factors are analyzed to obtain the characteristics of the structural parameter curves under different test conditions. The structural parameters of the Loess and the structural parameters of the Loess Based on the deformation (large main strain) method are not equal except for the starting point of the active action. Therefore, the structural parameters of the Loess should be indicated in the use of the method.
4. the structural single variable parameters of loess under dynamic load test are constructed respectively, that is, based on the same dynamic shear stress method and the single variable parameter of loess dynamic structural based on the same dynamic shear strain method. Three loess areas in Lanzhou, Luochuan and Yangling are tested by the dynamic torsion shear three axis test. In the three regions of Lanzhou, Luochuan and Yangling, the Loess movement is obtained. On the basis of the relationship between the shear stress and the dynamic shear strain curve, the experimental data are sorted by the single variable parameters of the constructed soil dynamic structure. The rationality of the single variable parameters of the loess dynamic structure under the dynamic load test condition is tested and the Loess movement based on the same dynamic shear stress method in three regions of Lanzhou, Luochuan and Yang Lingzhe is obtained. The structural single variable parameter curve and the single variable parameter curve of loess dynamic structural based on the same dynamic shear strain method are used to analyze the changes of dynamic structural changes of loess under dynamic conditions, and the difference of this characteristic in different regions.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TU444;TU43

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