An experimental investigation of mine burial penetration in soft sediments

Abstract

An experimental program was conducted to study the penetration behavior of mines in soft sediment. Model tests were conducted on sediments collected from the Gulf of Mexico seabed. The size of the model mine was approximately one third of that of actual mines. The factors selected for the investigation were mine weight, preburial condition of the mine, mine orientation, impact velocity of the mine and shear strength and creep characteristics of the soil. Only the geotechnical aspects of the problem were investigated. The model tests were divided into nonimpact and impact tests. In the nonimpact tests, the mine penetration behavior qualitatively follows the theoretical predictions of pipe penetration. Normalized mine weight vs. normalized penetration curve has a steeper slope when the penetration is less than one mine radius. When the penetration is more than one mine radius the mine tends to penetrate more readily with increasing mine weight. The preburial condition of the mine does not influence the penetration behavior, especially for long term penetration. Mine orientation plays a role in immediate penetration, but when the mine is in full contact with the soil, it does not influence penetration significantly. Creep behavior of the Gulf of Mexico soil was found to be of a terminating nature, which contributes significantly to long term penetration. In impact tests, the impact velocity of the mine plays the most important role in mine penetration. The acceleration induced in the mine due to free fall becomes negative after some amount of penetration. The mine gains ultimate penetration immediately after hitting the mud and does not penetrate further as time passes. So, soil creeping does not contribute to penetration when the mine is being impacted on sediment.