Mine impact burial model (IMPACT35) verification and improvement using sediment bearing factor method

Abstract

Recently, a 3-D model (IMPACT35) was developed to predict a falling cylindrical mine’s location and orientation in air–water–sediment columns. The model contains the following three components: 1) triple coordinate transform, 2) hydrodynamics of falling rigid object in a single medium (air, water, or sediment) and in multiple media (air–water and water–sediment interfaces), and 3) delta method for sediment resistance with the transient pore pressure. Two mine-impact burial experiments were conducted to detect the mine trajectory in water column [Carderock Division, Naval Surface Warfare Center (NSWC), West Bethesda, MD, on September 10–14, 2001], and to measure the mine burial volume in sediment (Baltic Sea in June 2003). The existing IMPACT35 predicts a mine’s location and orientation in the water column, but not in the sediment column. Since sediment resistance largely affects the mine burial depth and orientation in sediment, a new method (bearing factor) is proposed to compute the sediment resistant force and torque. The improvement of IMPACT35 with the bearing factor method is verified using the data collected from the Baltic Sea mine-impact burial experiment. The prediction error satisfies near-Gaussian distribution. The bias of the burial volume (in percent) prediction reduces from 11% using the delta method (old) to 0.1% using the bearing factor method (new). Correspondingly, the root-mean-square error (rmse) reduces from 26.8% to 15.8%.