【摘要】：我國黃土的分布具有特別明顯的氣候性和地域性，其分布地區(qū)主要位于中西部。由于該地區(qū)處于地震活動頻繁區(qū)，在地震及大變形振動條件下，常會使該區(qū)建筑物、構筑物的黃土地基與邊坡產(chǎn)生嚴重震陷、滑坡等地質(zhì)災害。本文以神河高速公路邊坡黃土為研究對象，采用動三軸試驗，研究非飽和黃土（原狀黃土和重塑黃土）受到重復荷載作用時，在不同固結圍壓、不同固結應力比、不同含水率條件下的動力學特性，由此探討非飽和黃土的動本構關系、動彈性模量、動阻尼比和動強度的變化規(guī)律。本文所取得的主要成果總結如下： （1）神河高速非飽和黃土在重復荷載作用下動應力-動應變關系曲線基本表現(xiàn)為雙曲線型，其中原狀黃土對雙曲線模型的擬合度高于重塑黃土；分別采用逐級加載和單級加載的方法，黃土動應力-動應變曲線表現(xiàn)出一定的差異；黃土動應力-動應變曲線受土體固結作用影響較為明顯，，在相同的動應變條件下，動應力大小隨固結圍壓和固結應力比值的增減同步增減；非飽和重塑黃土含水率在11%～19%范圍內(nèi)時，含水率對動應力-動應變曲線的形態(tài)幾乎沒有影響； （2）神河高速非飽和黃土的動彈性模量隨動應變的增大而減小，兩者之間的相關關系表現(xiàn)為隨著動應變增大到一定程度后，黃土動彈性模量減小幅度減弱。黃土動彈性模量隨初始固結圍壓、固結應力比值的增減同步增減；重塑黃土動彈性模量隨含水率的增大而減��； （3）神河高速邊坡非飽和原狀黃土的動阻尼比約為0.10～0.25，重塑黃土約為0.05~0.20，重塑黃土動阻尼比略小于原狀黃土，其原因在于黃土原位結構特性對其強度具有有利影響。通過對動三軸試驗的結果分析得出，非飽和黃土的含水率、固結圍壓、固結應力比直接影響著黃土的動阻尼比大小。黃土動阻尼比隨固結圍壓的增減同步增減；隨固結應力比的增大而減��；重塑黃土動阻尼比隨含水率大小的增減同步增減。原狀土的動阻尼比-動應力曲線關系較重塑土的曲線關系更具規(guī)律性； （4）黃土的性質(zhì)、黃土所處的應力狀態(tài)環(huán)境、黃土所受的振動應力直接影響著非飽和黃土的動強度。動強度試驗結果顯示：非飽和黃土動強度隨振動次數(shù)和固結應力比的增大而減小，隨初始固結圍壓的增減同步增減；影響非飽和黃土抵抗破壞變形的最直接因素是固結圍壓大小，但當固結比增大到一定程度后，非飽和黃土動強度的直接影響因素（固結圍壓）的影響作用在不斷減弱； （5）受非飽和黃土原位結構特性的影響，原狀土所能承受的極限動載荷相比于重塑土略大；采用逐級加載的方法測定原狀黃土的動強度，得出的結果高于單級加載測定的動強度值，該結果參數(shù)用于實際工程地基、邊坡的設計中偏于不安全；非飽和黃土動強度各個指標的定量參數(shù)均隨振次的增大呈現(xiàn)出減小的趨勢。
[Abstract]:The distribution of loess in China is particularly climatic and regional, and its distribution is mainly located in the central and western regions. Because this area is in the area of frequent seismic activity, under the condition of earthquake and large deformation vibration, the loess foundation and slope of the buildings and structures in this area often produce serious earthquake subsidence, landslide and other geological disasters. Taking the loess slope of Shenhe Expressway as the research object, the dynamic triaxial test is used to study the different consolidation confining pressure and the different consolidation stress ratio of unsaturated loess (undisturbed loess and remolded loess) under repeated loading. The dynamic properties of unsaturated loess under different moisture content are discussed. The dynamic constitutive relation, dynamic elastic modulus, dynamic damping ratio and dynamic strength of unsaturated loess are discussed. The main results obtained in this paper are summarized as follows: (1) the dynamic stress-strain relationship curve of Shenhe high speed unsaturated loess under repeated loads is basically hyperbolic. The fitting degree of original loess to hyperbolic model is higher than that of remolded loess. The dynamic stress-strain curve of loess is obviously affected by soil consolidation. Under the same dynamic strain condition, the dynamic stress increases or decreases with the increase or decrease of consolidation confining pressure and consolidation stress ratio. When the moisture content of unsaturated remolded loess is in the range of 11% or 19%, the water content has little effect on the shape of dynamic stress-strain curve, (2) the dynamic elastic modulus of Shenhe high speed unsaturated loess decreases with the increase of dynamic strain. The correlation between the two shows that the dynamic elastic modulus of loess decreases when the dynamic strain increases to a certain extent. The dynamic elastic modulus of loess increases and decreases synchronously with the initial consolidation confining pressure, while the dynamic elastic modulus of remolded loess decreases with the increase of water content. (3) the dynamic damping ratio of unsaturated undisturbed loess is about 0.10 ~ 0.25, that of remolded loess is about 0.05 ~ 0.20. The dynamic damping ratio of remolded loess is slightly smaller than that of undisturbed loess. The reason is that the in-situ structural characteristics of loess have favorable influence on its strength. By analyzing the results of dynamic triaxial tests, it is concluded that the moisture content, consolidation confining pressure and consolidation stress ratio of unsaturated loess directly affect the dynamic damping ratio of loess. The dynamic damping ratio of loess increases and decreases with the increase of consolidation confining pressure, decreases with the increase of consolidation stress ratio, and increases and decreases with the increase of moisture content of remolded loess. The relationship between dynamic damping ratio and dynamic stress curve of undisturbed soil is more regular than that of remolded soil. (4) the nature of loess, the stress state environment of loess, The vibration stress of loess directly affects the dynamic strength of unsaturated loess. The dynamic strength test results show that the dynamic strength of unsaturated loess decreases with the increase of vibration frequency and consolidation stress ratio, and increases and decreases with the increase or decrease of initial consolidation confining pressure. The most direct factor affecting the failure and deformation of unsaturated loess is the consolidation confining pressure, but when the consolidation ratio increases to a certain extent, the influence of the direct influence factor (consolidation confining pressure) on the dynamic strength of unsaturated loess is weakening. (5) under the influence of the in-situ structural characteristics of unsaturated loess, the ultimate dynamic load of undisturbed soil is slightly larger than that of remolded soil, and the dynamic strength of undisturbed loess is measured by stepwise loading method. The results obtained are higher than the dynamic strength values measured by single stage loading. The parameters of the results are used in the actual engineering foundation and the slope design is not safe. The quantitative parameters of each index of dynamic strength of unsaturated loess decrease with the increase of vibration frequency.
【學位授予單位】：太原理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU411;TU444

【參考文獻】

相關期刊論文 前10條

1 關飛,韓國城;有效應力動力分析方法的探討[J];地震工程與工程振動;1988年04期

2 段汝文;黃土地基的特性和抗震性能的評估[J];工業(yè)建筑;1992年11期

3 張建民，謝定義;飽和砂土動本構理論研究進展[J];力學進展;1994年02期

4 卞敬玲;高原黃土動力特征研究[J];青海師范大學學報(自然科學版);2002年03期

5 汪聞韶;往返荷載下飽和砂土的強度、液化和破壞問題[J];水利學報;1980年01期

6 謝定義,齊吉琳,朱元林;土的結構性參數(shù)及其與變形強度的關系[J];水利學報;1999年10期

7 駱亞生,田堪良;非飽和黃土的動剪模量與阻尼比[J];水利學報;2005年07期

8 巫志輝，謝定義，余雄飛;洛川黃土的動變形和強度特緊性[J];水利學報;1994年12期

9 駱亞生,謝定義,董為民,陳存禮;不同地區(qū)黃土振陷變形特性的對比分析[J];陜西水力發(fā)電;2001年01期

10 曾春華;關于土在重復載荷下動態(tài)特性的綜述[J];土木工程學報;1988年02期

本文編號：2255264