Impact of pressure of surrounding medium on plain water jet cutting of rocks

Abstract

The goal of this contribution is to investigate problems connected with the application of plain water jets in surroundings between jet outlet and target differing from standard atmosphere. Two cases are especially interesting from the practical viewpoint. Application of water jets under the water level, i.e., in pressurized water: it is sometimes necessary to perform certain reparations on dam walls, bridge pillars, and other structures under the water level without emptying the dam or changing the river flow. The second case particularly involves water jets used for cleaning of chemical or radioactive facilities, which is much safer if done in underpressure. By these reasons, behavior of plain water jets on several different rock materials was tested inside the pressure vessel with the application of normal air pressure, air underpressure, and water overpressure. The effectiveness of rock material disintegration by water jet in various environmental conditions has been described. The depth of penetration decreases with increasing water overpressure, approximately with the second degree of the overpressure value. The cut depth decreases with the increasing value of certain material characteristics. The cut depth decreases also with decreasing pressure of air between nozzle outlet and sample surface. The dependence seems to be linear within the experimental range.