Physical properties of silt.

Under the repeated action of aircraft taxiing load, the subgrade plastic deformation becomes the key factor affecting the service performance of the airfields when salinized silt is used to fill the subgrade. In this study, the dynamic triaxial tests were carried out on a region in the northern part of China to study the effects of different salt contents on the dynamic characteristics of silt under cyclic loading. A prediction model for the salinized silt dynamic strength with a plastic strain of 4% as the failure criterion for the subgrade was thus proposed. It is found that with the increase of dynamic stress amplitude, the salinized silt plastic deformation transforms gradually from plastic deformation to incremental failure. The salt contents significantly influence the plastic strain and critical dynamic stress of silt. The strength of the salinized silt specimen is related to the ion concentration in the soil pores and the arrangement pattern of soil particles, as indicated by the progressive strength increase of the salinized silt at the low salt content of 1% and a further gradual decrease at high salt content.

当采用盐渍粉土填筑机场道基时，在飞机滑行荷载的反复作用下，道基塑性变形成为影响机场服役性能的关键因素。本研究针对我国北方某区域的粉土开展动三轴试验，探究循环荷载作用下不同含盐量对粉土动力特性的影响规律。据此，本研究提出了以4%塑性应变作为道基破坏准则的盐渍粉土动强度预测模型。研究发现，随着动应力幅值的提升，盐渍粉土的塑性变形逐渐从累积塑性变形发展为渐进式破坏。含盐量对粉土的塑性应变与临界动应力具有显著影响。盐渍粉土试样的强度与土体孔隙内的离子浓度及土颗粒的排列形式密切相关，具体表现为：当含盐量较低（1%）时，盐渍粉土的强度随含盐量升高而逐步提升；而当含盐量进一步升高至较高水平时，其强度则逐渐降低。