A new model was developed to understand how saturated sand behaves under repeated twisting stress. By looking at how the sand changes in volume during this stress, the model can predict how excess water pressure builds up in the sand. The model was tested on Toyoura sand and found to accurately predict when loose sand might turn into liquid but slightly underestimated this risk for denser sand. Overall, the model is a good tool for predicting how sand behaves under certain types of stress.