| Acknowledgements | 第9-18页 |
| Abstract | 第18-22页 |
| 摘要 | 第23-26页 |
| Chapter 1 General introduction and literature review | 第26-45页 |
| 1.1. Introduction to vertic soils | 第26-28页 |
| 1.2. Occurrence and distribution | 第28-30页 |
| 1.3. Chinese Vertiosls | 第30-32页 |
| 1.4. General characteristics of vertic soils | 第32-39页 |
| 1.4.1. Mineralogical characteristics of vertic soils | 第33-36页 |
| 1.4.2. Chemical characteristics of vertic soils | 第36-37页 |
| 1.4.3. Physical characteristics of vertic soils | 第37-38页 |
| 1.4.4. Mechanical characteristics of vertic soils | 第38-39页 |
| 1.5. Choice of amendments for the improvement of vertic soils | 第39-43页 |
| 1.5.1. Biochar as an amendment | 第40-41页 |
| 1.5.2. Coal fly ash as amendment | 第41-42页 |
| 1.5.3. Wastewater sludge as an amendment | 第42-43页 |
| 1.6. Conclusion and overall objectives of the study | 第43-45页 |
| Chapter 2 Characterization of clay mineralogy of vertic soils of Northern China | 第45-70页 |
| 2.1. Introduction | 第45-47页 |
| 2.2. Materials and Methods | 第47-50页 |
| 2.2.1. Soil sampling and determination of soil basic properties | 第47-48页 |
| 2.2.2. Fractionation for<0.002mm clay minerals | 第48-49页 |
| 2.2.3. Particle size distribution (PSD) of clay minerals | 第49-50页 |
| 2.2.4. XRD analysis for clay minerals | 第50页 |
| 2.2.5. TEM and HRTEM analysis | 第50页 |
| 2.3. Results | 第50-64页 |
| 2.3.1. Basic properties and fractionation of studied profiles | 第50-51页 |
| 2.3.2. Particle size distribution (PSD) | 第51-54页 |
| 2.3.3. Mineral distribution of vertic soils of Northern China along the depth | 第54-56页 |
| 2.3.4. Clay mineralogy identified by XRD | 第56-60页 |
| 2.3.5. Morphology, chemical composition and lattice structure of clay minerals characterized by HRTEM | 第60-64页 |
| 2.4. Discussion | 第64-69页 |
| 2.4.1. Fractionation and particles size distribution (PSD) characteristics of clay minerals | 第64-66页 |
| 2.4.2. Mineralogical characteristics of vertic soils | 第66-67页 |
| 2.4.3. TEM study and morphological characteristics of clay minerals | 第67-69页 |
| 2.5. Conclusions | 第69-70页 |
| Chapter 3 Mechanical and physical properties and cracking characteristics of vertic soils of Northern China | 第70-97页 |
| 3.1. Introduction | 第70-73页 |
| 3.2. Materials and Methods | 第73-77页 |
| 3.2.1. Soil description and experiment layout | 第73-74页 |
| 3.2.2. Particle size distribution (PSD) of soil | 第74页 |
| 3.2.3. Determination of soil mechanical and physical properties | 第74-75页 |
| 3.2.3.1. Coefficient of linear extensibility (COLE) | 第74-75页 |
| 3.2.3.2. Soil strength (Tensile and Shear strength) | 第75页 |
| 3.2.5. Soil cracking analysis | 第75-76页 |
| 3.2.6. Statistical analysis | 第76-77页 |
| 3.3. Results | 第77-89页 |
| 3.3.1. Basic properties of studied profiles | 第77-78页 |
| 3.3.2. Mechanical and physical properties(COLE,Tensile Strength and Shear strength) | 第78-81页 |
| 3.3.4. Soil Cracking | 第81-82页 |
| 3.3.6. Principal component analysis | 第82页 |
| 3.3.7. Effect of temperature,water contents and amendments on cracking of vertic soils | 第82-89页 |
| 3.4. Discussion | 第89-96页 |
| 3.4.1. Physical properties and COLE | 第89页 |
| 3.4.2. Mechanical strength of studied profiles | 第89-92页 |
| 3.4.3. Cracking characteristics of studied profiles | 第92-93页 |
| 3.4.4. Effect of temperature and water contents on the cracking and improving the cracking capacity of vertic soils due to amendments | 第93-96页 |
| 3.5. Conclusions | 第96-97页 |
| Chapter 4 Porosity and pore size distribution of vertic soils of Northern China and correlation to soil organicmatter | 第97-122页 |
| 4.1. Introduction | 第97-99页 |
| 4.2. Materials and Methods | 第99-102页 |
| 4.2.1. Soils | 第99-101页 |
| 4.2.2. Nitrogen adsorption(NA) | 第101页 |
| 4.2.3. Mercury intrusion porosimetry(MIP) | 第101-102页 |
| 4.2.4. Organic matter removal | 第102页 |
| 4.3 Results | 第102-114页 |
| 4.3.1. Basic properties of three vertic soils | 第102-104页 |
| 4.3.2. Soil porosity and pore size distribution of six profiles of Northern China | 第104-108页 |
| 4.3.3. Porosity analysis of three vertic soils before and after of organic removal | 第108-114页 |
| 4.3.3.1. Nitrogen adsorption isotherms | 第108-109页 |
| 4.3.3.2. Pore size distribution based on nitrogen adsorption | 第109-110页 |
| 4.3.3.3. Pore size distribution based on MIP | 第110-112页 |
| 4.3.3.4. Effect of organic matter on pore structure | 第112-114页 |
| 4.4. Discussion | 第114-120页 |
| 4.4.1. Porosity and pore size distribution of six profiles | 第114-116页 |
| 4.4.2. Pore structure of vertic soils before and after organic matter removal | 第116-120页 |
| 4.4.2.1. Comparison of the NA and MIP methods | 第118-119页 |
| 4.4.2.2. Role of organic matter in the soil pore formation | 第119-120页 |
| 4.5 Conclusions | 第120-122页 |
| Chapter 5 Improvement of mechanical and physical properties of vertic soils | 第122-146页 |
| 5.1. Introduction | 第122-124页 |
| 5.2. Materials and Methods | 第124-130页 |
| 5.2.1. Soil description and experiment details | 第124-125页 |
| 5.2.2. Soil physical and chemical properties analysis | 第125-126页 |
| 5.2.3. Determination of consistency limits | 第126页 |
| 5.2.4. Determination of COLE | 第126-127页 |
| 5.2.5. Determination of tensile strength and shear strength | 第127页 |
| 5.2.6. Determination of swelling potential and swelling pressure | 第127-129页 |
| 5.2.7. Statistical analysis | 第129-130页 |
| 5.4. Results | 第130-139页 |
| 5.4.1. Effect of amendments on the consistency limit of vertic soil | 第130-131页 |
| 5.4.2. Effect of amendments on the COLE | 第131-132页 |
| 5.4.3. Effect of amendments on the strength (tensile and shear strength) of vertic soil | 第132-135页 |
| 5.4.4. Effect of amendments on the swelling potential (SP) and swelling pressure (SPr) | 第135-138页 |
| 5.4.5. Correlation among the studied physical parameters | 第138-139页 |
| 5.5. Discussion | 第139-144页 |
| 5.5.1. Improvement in the consistency limit and COLE | 第139-140页 |
| 5.5.2. Improvement in the tensile and shear strengths | 第140-143页 |
| 5.5.3. Improvement in the swelling potential and swelling pressure | 第143-144页 |
| 5.6. Conclusions | 第144-146页 |
| Chapter 6 Major conclusions and perspectives | 第146-149页 |
| 6.1 Major findings | 第146-148页 |
| 6.2 Future challenges and recommendations | 第148-149页 |
| References | 第149-168页 |
