# Research on the Accumulated Plastic Strain of Expansive Soil under Subway Loading
## 6 Conclusions  
Taking the saturated remolded expansive soil in Hefei City as the research object, the dynamic characteristics of the soil under intermittent and continuous subway loading conditions were investigated through cyclic triaxial tests. The research aimed to explore the influence of intermittent and continuous loading modes on the dynamic behavior of saturated remolded expansive soil. The study also analyzed the effects of intermittent loading ratio, cyclic stress ratio, and static deviator stress on the variation of cumulative plastic strain with the number of cycles. Based on the test results, the following conclusions can be drawn:  
Under both intermittent and continuous subway loading, the accumulated plastic strain of saturated remolded expansive soil exhibited a similar development pattern of rapid growth-slow growth-eventual stabilization. It can be inferred that intermittent loading does not alter the overall trend of strain development but does show differences in the initial accumulation rate and final development of plastic strain. Comparative analysis revealed that the initial development rate of accumulated plastic strain was higher under intermittent loading conditions than under continuous loading conditions, and intermittent loading facilitated a quicker stabilization of cumulative plastic strain in the soil. Under intermittent subway loading with other test conditions being the same, a larger intermittent loading ratio resulted in smaller accumulated plastic strain at the same number of cycles, and the accumulated plastic strain value at stabilization was also smaller. Static deviatoric stress and cyclic stress ratio have a significant cumulative effect on plastic strain. When static deviatoric stress increases by one time, the accumulated plastic strain under intermittent subway cyclic loading increases by about 1.5 times. When the cyclic stress ratio increases by one time, the accumulated plastic strain increases by about 1-2 times. Based on the cumulative plastic strain development behavior under intermittent subway cyclic loading, an enhanced calculation model for cumulative plastic strain as a function of cycle count was proposed, building upon the Long-Yao hyperbolic \begin{table}
\begin{tabular}{c c c c} \hline
**Soil Sample Number** & **Fitting Parameter \(a\)** & **Fitting Parameter \(b\)** & **Fitting Parameter \(c\)** & **Correlation Coefficient \(\mathbf{R^{2}}\)** \\ \hline S7 & 0.00182 & 0.00517 & \(-\)0.04868 & 0.99925 \\ S8 & 0.01350 & 0.01123 & 0.00458 & 0.99887 \\ S9 & 0.02542 & 0.01213 & \(-\)0.02809 & 0.99766 \\ S10 & 0.01363 & 0.02225 & \(-\)0.0058 & 0.99926 \\ S11 & 0.03001 & 0.01060 & \(-\)0.01619 & 0.99878 \\ S12 & 0.05009 & 0.01008 & \(-\)0.02974 & 0.99837 \\ S13 & 0.00133 & 0.00534 & \(-\)0.06115 & 0.99972 \\ S14 & 0.00583 & 0.00764 & \(-\)0.05782 & 0.9994 \\ S15 & 0.01951 & 0.0118 & \(-\)0.02916 & 0.99958 \\ S16 & 0.01622 & 0.01264 & \(-\)0.0248 & 0.99946 \\ S17 & 0.01559 & 0.00849 & \(-\)0.06604 & 0.99952 \\ S18 & 0.03136 & 0.00798 & \(-\)0.03901 & 0.99825 \\ S19 & 0.00173 & 0.00897 & \(-\)0.05603 & 0.9996 \\ S20 & 0.00827 & 0.01494 & \(-\)0.04905 & 0.99979 \\ S21 & 0.01871 & 0.01713 & \(-\)0.03461 & 0.99978 \\ S22 & 0.01168 & 0.02225 & \(-\)0.0058 & 0.99926 \\ S23 & 0.01336 & 0.00987 & \(-\)0.04763 & 0.99919 \\ S24 & 0.02545 & 0.0103 & \(-\)0.05811 & 0.99913 \\ S25 & 0.00384 & 0.02234 & 0.00511 & 0.99869 \\ S26 & 0.01486 & 0.03105 & 0.0196 & 0.99966 \\ S27 & 0.02068 & 0.02263 & 0.00211 & 0.99929 \\ S28 & 0.02723 & 0.06080 & 0.13971 & 0.99741 \\ S29 & 0.02697 & 0.02311 & \(-\)0.01206 & 0.9991 \\ S30 & 0.03289 & 0.01593 & \(-\)0.05258 & 0.99914 \\ \hline \end{tabular}
\end{table} 
Table 3: Accumulated plastic strain model parameters under intermittent loading conditions. model. This model takes into account factors such as intermittent loading ratio, static bias stress, and cyclic stress ratio. The coefficient of determination (R\({}^{2}\)) for this model is remarkably close to 1, affirming its high degree of fitness to the data.