PROCESS AND APPARATUS FOR DETERMINING THE ERODABILITY OF SOIL,IN PARTICULAR SOIL BELONGING TO THE UNDERWATER FLOOR

摘要

To determine the erodability of soil, in particular soil belonging to the underwater floor, a vertically displaceable spray nozzle is installed above the floor to produce a water flow onto or over the floor soil. The water flow forms a pit in the soil by erosion. The spray nozzle is systematically lowered by means of displacement means in a manner such that the nozzle follows the descending pit floor. The speed at which the spray nozzle follows the pit floor is determined and the erodability is derived at various depths from the relationship between this speed and the flow rate of the water flow. To obtain an accurate and reproduceable determination of the erodability a quantity, which is a function of the distance between the bottom end of the spray nozzle and the floor of the pit, is measured with a sensor fitted to the spray nozzle. This quantity is used to regulate a servo system which controls the displacement means of the spray nozzle in a manner such that the distance between the bottom end of the spray nozzle and the floor of the pit remains essentially constant.