本文選題：黃土　切入點：單變量結構勢參數(shù)　出處：《西北農(nóng)林科技大學》2014年博士論文

【摘要】：土的結構性是土物理狀態(tài)的顯示，是土生成條件、環(huán)境的自然歷史產(chǎn)物。土的力學性質(zhì)受其結構性的影響。黃土是一種典型的結構性土，具有獨特的結構特性，容易發(fā)生“崩潰”性突變。這一現(xiàn)象不僅表現(xiàn)為黃土結構的“水敏性”，同時在動荷載作用下還表現(xiàn)出易損性。黃土在我國有著廣泛的分布，工程病害及相關巖土工程問題在這一區(qū)域較為突出。因此，研究黃土的結構特性，考察黃土結構性與黃土濕陷、振陷等工程性質(zhì)的關系，揭示其變化機理，對于指導黃土地區(qū)的工程實踐具有重要的意義。本文在總結前人黃土結構性研究成果的基礎之上，建立了單變量黃土結構勢參數(shù)。通過側限壓縮試驗、動扭剪試驗研究了不同條件下黃土結構性及其結構勢參數(shù)的變化規(guī)律，分別建立了黃土增濕變形系數(shù)、振陷系數(shù)與結構勢參數(shù)的關系，拓展了結構性定量化參數(shù)的應用空間。本文成果如下： 1）總結了結構性研究成果，分析了黃土結構勢參數(shù)的建立機制，建立了單變量黃土結構勢參數(shù)。通過化簡，靜荷載條件下黃土結構變形勢參數(shù)可用割線模量描述，進一步地可以獲得以應力為變量的單變量黃土結構變形勢參數(shù)；循環(huán)荷載條件下黃土結構動強度勢參數(shù)可用動剪切模量描述，相應地獲得了以動剪應變?yōu)樽兞康膯巫兞奎S土結構動強度勢參數(shù)。 2）通過應變比擬，建立了黃土結構動變形勢參數(shù)。進一步化簡，獲得以動剪應力為變量的單變量黃土結構動變形勢參數(shù)。對黃土結構動強度勢參數(shù)和結構動變形參數(shù)二者之間的關系進行了分析。 3）通過對楊凌、洛川兩地黃土側限壓縮試驗研究了靜荷載條件下原狀黃土結構變形勢參數(shù)的變化規(guī)律，揭示了含水率和壓力對黃土結構性的影響規(guī)律。分析了相同壓力條件下含水率對黃土割線模量的影響規(guī)律，以此為基礎建立了黃土結構變形參數(shù)與含水率之間的關系。 4）通過化簡黃土增濕變形系數(shù)，獲得以割線模量為參數(shù)的表達式。進一步與黃土結構變形勢參數(shù)相聯(lián)系，建立了黃土增濕變形系數(shù)與黃土結構變形勢參數(shù)之間的關系，揭示了黃土結構勢參數(shù)對黃土增濕變形系數(shù)的影響規(guī)律。分析了含水率、壓力對二者關系的影響。 5）通過對楊凌黃土動扭剪試驗研究循環(huán)荷載作用下原狀黃土的結構動變形勢參數(shù)和結構動強度勢參數(shù)的變化規(guī)律。揭示圍壓、含水率、動剪應力、動剪應變對黃土結構性的影響規(guī)律。分析了相同動剪應變條件下，含水率對黃土動剪切模量的影響規(guī)律，建立了黃土結構動強度勢參數(shù)與含水率之間的關系。 6）通過動扭剪試驗研究了振次、含水率、圍壓、動剪應力等因素對黃土振陷特性的影響規(guī)律。建立了振陷系數(shù)與動剪應力之間的關系式，并使之與黃土結構動變形勢參數(shù)相聯(lián)系，，建立黃土振陷系數(shù)與黃土結構動變形勢參數(shù)之間的關系式。揭示了黃土結構動變形勢參數(shù)對黃土振陷系數(shù)的影響規(guī)律，分析了含水率、圍壓對二者關系的影響。
[Abstract]:The structural soil is a soil physical state that is soil formation conditions, natural history of product environment. Mechanical properties of soil under the influence of structural loess is a kind of typical structural soil, unique structure, prone to "collapse" mutation. This phenomenon not only showed the loess structure "water sensitivity", at the same time under dynamic loading also showed the vulnerability of loess in our country has a broad distribution of engineering disasters and related geotechnical engineering problem is more prominent in this area. Therefore, the structure characteristics of loess, loess structure investigation and collapsibility of loess, the relationship between vibration depression the engineering properties, the mechanism has important significance for the engineering practice in the loess area. Based on the former research achievements of structural loess, established a single variable structure of loess through the side pressure limiting potential parameters. Shrinkage test, variation of dynamic torsional potential parameters of loess and its structure under different conditions of shear test were established, the moistening deformation of loess seismic subsidence coefficient, relationship between the coefficient and the structure parameters of potential, expand the application space of structural quantitative parameters. The results are as follows:
1) summarizes the structural research results, establish the mechanism analysis of the structure of the potential parameters, a single variable loess structure potential parameters. Through simplification, describe the situation variable parameters available secant modulus of loess structure under static loading, the stress of the situation can be obtained by varying parameters of single variable loess structure variable cycle; the load condition of loess under dynamic structural potential parameter available dynamic shear modulus, obtained by dynamic shear strain dynamic strength potential parameters into a single variable loess structure variable.
2) through the strain analogy, we established the dynamic change situation parameters of loess structure. Further simplification, we obtained the single variable loess structural dynamic change situation parameters with dynamic shear stress as variables. We analyzed the relationship between the dynamic strength potential parameters of loess structure and the dynamic deformation parameters of the two.
3) in Yangling, Luochuan loess unconfined variation of loess structure change situation parameters under static loading compression test, reveals the water content and pressure on the influence law of loess structural. Analyze the influence of secant modulus of loess under the same pressure condition of water content, is established on the basis of the structure of the relationship between the deformation parameters and water content.
4) by simplifying the moistening deformation coefficient, secant modulus for expression to parameters. Further and loess structure situation parameter associated, established the moistening deformation of loess relations between parameters and variable coefficient of loess structure, reveals the influence law of loess structure potential parameters of moistening deformation coefficient on yellow soil. Analysis of the water content, the effect of pressure on the relationship between the two.
5) through the Yangling loess dynamic torsional shear test of loess structure under cyclic loading dynamic variation situation of strength potential parameters of dynamic parameters and structure change. To reveal the moisture content, confining pressure, shear stress, shear strain on the influence law of loess structure. The dynamic shear strain is analyzed in the same conditions. Effect of water content on the regulation of the loess dynamic shear modulus, establish the relationship between the strength of the potential parameters and water content of loess structure.
6) through the study of dynamic torsional vibration shear test, moisture content, confining pressure, the dynamic influence of shear stress and other factors on the vibration characteristics of depression was established. Dynamic subsidence coefficient and shear stress relation between stress, and loess structure change situation parameters linked to establish the vibration relation between dynamic parameters in variable situation coefficient and loess structure. The influences of dynamic change of loess structure parameters on the vibration situation in the analysis of the moisture content, the effect of confining pressure on the relationship between the two.

【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TU444

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