Partial Field Validation of the Surfzone Transition Analytical Methodology (STAM)

Abstract : Results from field tests of the full-size tracked Surfzone Test Vehicle (STV) conducted over a two-week period at two sandy beach/nearshore sites were used to investigate some key vehicle performance prediction relations in the trafficability submodel of the computerized Surfzone Transition Analytical methodology (STAM). Analysis of the STV test results, along with results from related tests of full-size tracked vehicles and model tracks, demonstrated that STAM equations for predicting the drawbar pull and total motion resistance of tracked vehicles are adequate and, in fact, slightly conservative for nearly all coarse-grained soil/tracked vehicle/vehicle submergence conditions. For extreme conditions of low coarse-grained soil strength and high tracked vehicle ground contact pressure, modifications were made to the trafficability submodel relations to predict significantly smaller values of tracked vehicle drawbar pull. Finally, suggestions were presented for needed model and prototype testing to validate prediction relations in STAM's other two submodels--the water force calculations and vehicle stability submodels--as well as prediction relations in yet unvalidated parts of STAM's trafficability submodel (primarily relations for obstacle override and for tracked vehicle operation in fine-grained soil near-shore areas).