Levels of factors in orthogonal test.

Aiming at the influence of dynamic loading and wet/dry cycles during the operation of roadbed and in response to the proposal of Guizhou Provincial Government to promote the efficient utilization of phosphogypsum to solve the current situation of oversupply of phosphogypsum, the dynamic triaxial experiment was carried out to explore the dynamic constitutive model of phosphogypsum-stabilized soil with different numbers of wet/dry cycles, different peripheral pressures, and different consolidation ratios. The test results show that: (1) the effect of wet and dry cycles has a greater impact on the dynamic constitutive model of the mix, Monismith exponential model is suitable for the dynamic stress-strain curves in the case of wet and dry cycling; (2) The dynamic shear modulus-dynamic shear strain constitutive model of phosphogypsum stabilized soil was established based on dynamic soil mechanics, and the fitted correlation coefficients were all higher than 0.85, and the maximum values of MAE and RMSE were 4.827 and 5.990, respectively; (3) The prediction of the dynamic resilience modulus of phosphogypsum stabilized soil can be fitted by Ni model and power exponential model; (4) By comparing the dynamic and static modulus of rebound, it is concluded that the value of dynamic modulus of rebound for phosphogypsum-stabilized soil under dry and wet cycles is 1.1–1.5 times of the static modulus of rebound, and the recommended value of dynamic modulus of rebound is 90–100 MPa.

针对路基运行过程中动荷载与干湿循环的影响，响应贵州省政府提出的推进磷石膏高效利用以解决当前磷石膏产能过剩现状的倡议，本次研究开展动三轴试验，探究不同干湿循环次数、不同围压及不同固结比下磷石膏稳定土的动力本构模型。试验结果表明：(1) 干湿循环对该混合料的动力本构模型影响更为显著，莫尼史密斯指数模型（Monismith exponential model）适用于经历干湿循环后的动应力-应变曲线；(2) 基于土动力学理论建立了磷石膏稳定土的动剪切模量-动剪切应变本构模型，拟合相关系数均高于0.85，平均绝对误差（Mean Absolute Error, MAE）与均方根误差（Root Mean Square Error, RMSE）的最大值分别为4.827和5.990；(3) 磷石膏稳定土的动回弹模量可通过Ni模型与幂指数模型进行拟合预测；(4) 通过对比动、静回弹模量，得出经历干湿循环后的磷石膏稳定土动回弹模量为静回弹模量的1.1~1.5倍，推荐动回弹模量取值为90~100 MPa。