Overall understanding of the factors for inelastic behaviour of geomaterial and their interactions

通过进行大量排水平面应变试验、三轴压缩试验和直接剪切试验，研究了影响土工材料（即粘土、砂、砾石、水泥混合土、土工合成钢筋、EPS等）应力-应变行为的因素、粘度、无粘循环加载效应和老化，以及这些因素与弹塑性性能的相互作用。建立了一个通用的本构模型，可以模拟上述问题，并可用于岩土工程边值问题的数值分析。主要研究结果如下：首先，根据颗粒形状和级配的不同，岩土材料表现出不同的黏度类型，可分为1)等黏度、2)复合黏度、3)TESRA黏度和4)正负黏度（P&N）。isotachach的强度随应变速率的增加而增加，而TESRA在不同应变速率但不变的单调加载下强度相同，P&N的强度随应变速率的增加而降低。这些黏度类型具有正分量，因为应力随应变速率的突然增加而增加，并且在持续1期间应变增加

Factors, viscosity, inviscid cyclic loading effect and ageing, which affect the stress-strain behaviour of geomaterial (i.e., clays, sands, gravels, cement-mixed soils, geosynthetic reinforcement, EPS etc.) as well as interactions of these factors with elasto-plastic properties were investigated by performing a great amount of drained plane strain and triaxial compression tests and direct shear tests. A general constitutive model that can simulate the above and can be used in numerical analysis of geotechnical boundary-value problems was developed. The major findings include the followings. Firstly, the geomaterial exhibits different viscosity types depending on particle shape and grading, categorized as 1) Isotach, 2) Combined, 3) TESRA and 4) Positive and Negative (P&N). Isotach is characterized by an increase in the strength with strain rate, while TESRA by the same strength in monotonic loading at different but constant strain rates and P&N by a decrease in the strength with an increase in the strain rate. These viscosity types have a positive component in that the stress increases upon a sudden increase in the strain rate and the strain increases during sustained 1