Authors

Abstract

In order to study the compressive creep properties and laws of paddy soil, multi-stress creep experiments of paddy soil with different moisture content were carried out. The results show that the creep deformation of paddy soil, subjected to compressive loads effect, develops stably and the paddy soil is not destructed under the yield strength when the stress is low. When the stress level is higher than the yield strength, the internal damage of paddy soil would be caused at the moment of loading. With the extension of creep time, the cracks would gradually expand, resulting in the soil to yield, break and disintegrate. According to the analysis of the deformation properties of paddy soil under compression and the change trend of creep curve, the nonlinear viscoelastic-plastic model was composed of the nonlinear viscoplastic model and Burgers model in series. The creep test curve was introduced into the model for fitting, and the coefficient of determination reached more than 0.96. Based on the model, the strain composition, strain proportion, and strain rate of paddy soil were studied. Finally, the nonlinear model was compared with Burgers model by verification test. The fitting accuracy of the nonlinear model was better than Burgers model, and the coefficient of determination and relative error were 0.997 and 0.437%, respectively, which proved the rationality and correctness of the nonlinear viscoelastic-plastic model. This study can provide a theoretical basis for the optimization of tillage machinery structure and the simulation analysis of soil tillage and compaction.

Abstract in Chinese

为研究水稻土受压蠕变性能，探究其蠕变规律，以不同含水率的水稻土为试验对象进行多应力蠕变试验。试验结果表明水稻土在持续受压载荷作用下，应力水平较低时，蠕变变形发展稳定，不会发生失效破坏；应力水平大于屈服强度时，加载瞬间就会导致土壤内部损伤，随着蠕变时间延长，裂纹逐渐扩展致使土壤受压屈服破坏解体。通过分析水稻土受压变形特征和蠕变曲线变化趋势，将非线性黏塑性模型与Burgers模型串联组成非线性黏弹塑性模型，并将蠕变试验曲线引入该模型进行拟合，决定系数均达到0.96以上。基于推导的模型探究了水稻土受压蠕变各应变组成、应变占比以及应变速率规律，最后通过验证试验将该非线性模型与Burgers模型进行对比，结果表明非线性模型拟合精度优于Burgers模型，其决定系数和相对误差分别为0.997、0.437%，证实了所建立的非线性黏弹塑性模型的合理性与正确性。本研究可为耕作机械结构优化及土壤耕作、压实等相关仿真分析提供理论依据。