基于软黏土微观结构的宏观力学机制研究

Soil characteristics depend mainly on its microstructure. According to this common view mentioned, many researchers devoted themselves to the research of soil microstructure from qualitatively to quantitatively. Many valuable results were obtained. However there are very few results which can be applied to macro-mechanical calculation. In order to achieve that research results of microstructure can be applied to mechanics calculation，new techniques including scanning elcetronic microscope, computer image processing technique will be employed in the project. As a breakthrough of that soil contact areas measured, the relationship between soil porosity and its contact area will be explored on the basis of gray threshold partition method of soil porosity measured. Effective stress equation will be developed which can reflect effects of soil contact area. After that, macro-mechanics mechanism of new shear strength criterion, new constitutive model etc can be established. New theories can be verified by indoor large-scale model tests and centrifuge tests and improved with numerical analysis and case application. The research will contriute to enrich and develop theoretical system of modern soil mechanics. The project will result in an important theoretical significance and engineering application value.

土的微观结构很大程度上决定了土的宏观力学行为，基于这一认识，许多学者开展了土的微观结构的研究，从定性研究向定量研究发展，并取得了许多有价值成果，但是，迄今为止能应用于宏观力学计算的成果非常缺乏。为实现微观结构研究成果应用到宏观力学计算的跨越，项目组拟采用SEM图像技术和IPP读图技术研究软黏土的微观结构，以测定微观结构接触面积为突破口，根据实测孔隙率的灰度阈值分割方法，探索软黏土的孔隙率和微观接触面积的定量关系，进而实现可考虑接触面积影响的软黏土有效应力计算，在此基础上，建立新的抗剪强度准则、力学模型等宏观力学计算理论。通过室内大型模型试验和离心机模型试验验证提出的新理论，并通过数值分析和实例应用，进一步完善理论成果。项目组针对软黏土的微观结构演变规律的宏观力学机制研究有助于丰富和发展现代土力学理论体系，具有重要理论意义和工程应用价值。

为了实现微观结构研究成果应用到宏观力学计算的跨越，项目研究采用扫描式电子显微镜（SEM）图像技术和计算机读图技术研究黏性土的微细结构，依据实测孔隙率的灰度阈值分割方法，以测定微观结构接触面积为突破口，建立了黏性土的孔隙率和微观接触面积的定量关系，进而实现可考虑接触面积影响的粘性土有效应力计算，在此基础上，建立新的抗剪强度、地基承载力和固结理论等方面的宏观力学计算。通过室内大型模型试验和离心机模型试验验证提出的新理论，并通过数值分析和工程应用研究，进一步完善理论成果。项目研究对粘性土的微观结构演变规律的认识和土力学新理论的发展具有重要理论意义和工程应用价值。.经过四年的研究，取得了预期成果，项目达到预期目标。出版专著1部，共发表论文17篇，授权专利3项，培养博士3名，硕士4名。