纳米材料改性滨海水泥土的小应变特性与微观机理

Based on coastal soft soil foundation, separate and combination tests of conventional triaxial, bending element, resonant column and local strain will be carried out to explore the mechanical properties of five kinds of soil samples of original coastal soft soil, remodeling coastal soft soil, cement modified coastal soft soil, nano clay modified cement soil and nano-magnesia modified cement soil under different magnitudes in a small strain range. The microstructures of the above soil samples will be characterized by SEM-EDS, XRD, SAP and TGA testing techniques. The microstructures of spatial particle characteristics, pore characteristics and lattice transformation will be characterized, and the effects of filling, cementation and secondary excitation of nano-materials on cement soil will be investigated. Six curing ages from 1d to 90d are designed for all the test samples. The microscopic mechanism of the macroscopic mechanical properties of nano-modified cement soil will be revealed, and the time effect theory of mechanical behavior of nano-modified cement soil will be established on the basis of microscopic mechanism. By introducing the stress-strain curve within a small strain range and the characteristic parameter of micro-deformation, the structural potential energy of nano-modified cement soil will be explored from the aspects of friction potential energy, viscous potential energy and chemical potential energy. According to thermodynamics law, energy dissipation principle and micro-chemical kinetics principle, and from the perspective of governing differential equation, the unified mathematical model of stress-strain curve for nano-modified cement soli under small strain state and conventional strain state will be established.

以滨海相软土地基为背景，开展常规三轴、弯曲元、共振柱、局部应变的单独及组合测试，探索原状和重塑滨海软土、水泥改性滨海软土、纳米黏土改性水泥土、纳米氧化镁改性水泥土等5种土样在不同量级下小应变范围内的力学特性。采用SEM-EDS、XRD、SAP、TGA等测试技术对以上土样开展微观测试，表征其空间颗粒特征、孔隙特征、晶格物项转化等微观结构，探索纳米材料对水泥土的填充作用、胶结作用、二次激发作用。各试样均考虑1d至90d共6个养护龄期，揭示纳米改性水泥土宏观力学特性的微观机理，初步建立基于微观机理的纳米改性水泥土力学行为时间效应理论。引入小应变范围内应力应变曲线和微观变形的特征参量，从摩擦势能、粘聚势能、化学势能的角度探索纳米改性水泥土的结构势能，结合热力学定律、能量耗散原理、微观化学动力学原理，从应变控制微分方程的角度，建立小应变状态和常规应变状态下的纳米改性水泥土应力应变曲线的统一数学模型。

本项目以滨海相软土地基为背景，开展常规三轴、弯曲元、共振柱、局部应变的单独及组合测试，探索原状和重塑滨海软土、水泥改性滨海软土，纳米黏土、纳米氧化镁、纳米氧化硅、聚丙烯纤维、再生砂等多种材料单独/复合改性水泥土土样在不同量级下小应变范围内的力学特性。采用SEM-EDS、XRD、SAP、TEM、XPS等测试技术对以上土样开展微观测试，表征了其空间颗粒特征、孔隙特征、晶格物项转化、吸附性能等微观结构，探索纳米材料对水泥土的填充作用、胶结作用、二次激发作用和吸附作用。考虑了不同养护龄期，揭示了纳米改性水泥土宏观力学特性的微观机理，初步建立基于微观机理的纳米改性水泥土力学行为时间效应理论，基本确定了纳米复合材料改性滨海水泥土的组份配比范围。引入小应变范围内应力应变曲线和微观变形的特征参量，从学科交叉的角度探索纳米复合改性水泥土的改性机理，引入岩土工程多次重复测量的数据处理方法，建立小应变状态和常规应变状态下的纳米改性水泥土应力应变曲线的统一数学模型。项目成果已初步应用于滨海软土路基的加固处理。本项目圆满完成了预期目标。 发表论文国内外权威期刊SCI/EI收录论文13篇，其中sci一区top期刊3篇，另有2篇论文为ESI高被引论文；获得授权发明专利6项，出版专著1部；结合本课题培养研究生10余名；主要研究成果获浙江省科技进步二等奖一项。