Study on accumulative plastic deformation of cement-fly ash improved subgrade coarse-grained soil under heavy-haul traffic loads and relative prediction based on PSO-ANN

In order to study the accumulative plastic deformation characteristics of coarse-grained subgrade soil improved by cement-fly ash under heavy-haul traffic loads, and propose the corresponding prediction model, a series of dynamic performance tests were conducted under varying axial dynamic stress amplitudes, confining pressures and additive contents to acquire accumulative plastic strain-vibration times relationship curve. Subsequently, an accumulative plastic strain prediction model trained by PSO-ANN was developed. The research shows that as the axial dynamic stress amplitude gradually increases, the accumulative plastic strain of the specimen also increases under constant vibration frequency.The accumulative plastic strain of coarse-grained soil gradually decreases with increasing confining pressure.Higher additive content leads to smaller accumulative plastic strain under the same vibration.Compared to the traditional ANN model, the PSO-ANN model more accurately describes the accumulative plastic deformation behavior, demonstrating the superiority of the prediction model. The generalization ability of the model was analyzed and the prediction potential of the model was also proved.This research offers crucial practical guidance for both expanding and refurbishing existing heavy-haul railways, as well as for designing new heavy-haul railway improved soil subgrade.