Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Experimental study on the cutting characteristics of high-pressure water jet on lightweight concrete
1Jifu Yin 1,2, Zhongwei Zhou1,2, Guojun Hong 1,2 ,Gongxun Liu 1,2National Engineering Research Center of Dredging Technology and Equipment, Shanghai, China
2
Key Lab of Dredging Technology, MOC, Shanghai, China

ABSTRACT

makes the related numerical simulation and experimental research moredifficult. The real physical process mechanism always research failuresof rock cutting by high-pressure water jet. This affects the development
and application of high-pressure water jet rock breaking in dredging
engineering.

In the dredging and process test base of the Dredging National
Engineering Research Center, the characteristics of high-pressure water
jet cutting lightweight concrete were systematically studied. The failure
mechanism of high-pressure water jet cutting lightweight concrete
under the conditions of different nozzle diameter, different nozzle
moving speed and different jet angle was studied. During the test, thehigh-pressure jet system is moved by high-precision positioning andmobile crane system. The nozzle adopts cylindrical nozzle and ceramiccore to prevent nozzle wear during high-speed water flow. The highpressure jet system used in the test can provide pressure and can beadjusted during the experiment. The test results show that forlightweight concrete with compressive strength in the range of 810MPa, high-pressure flushing can effectively break the lightweight
concrete. The depth increases with the increase of jet pressure, anddecreases with the moving speed.The test results provide a theoreticalbasis for the high-pressure water jet cutting rock breaking systemequipped with dredging equipment such as trailing suction dredgers andcutter suction dredgers.

At present, the pressure of high-pressure jet commonly used bydomestic suction dredgers is only 1-2MPa, which can only be applied
to loose soil. When encountering cohesive soil, hard soil andcompacted soil with small permeability coefficient, due to the highshear strength of soil, the effect of high-pressure jet is significantly
reduced. At the same time,hard clay and weathered rock are broken intolarge pieces during excavation, which are easy to block rake head grilleand mud pump. In recent years, there are hard clay in some areas ofwaterway dredging projects, and the existing ships are inefficient oreven unable to construct, not to mention the application of pressure
flushing to rock breaking (Yin, 2019; 2021).
Dredgers and related equipment are mostly concentrated in a few
industrialized countries such as the Netherlands, Belgium, the UnitedStates, Germany and Japan, and most of them have a history of R&D
and manufacturing for more than 100 years. In terms of R&D
institutions, MTI Laboratory of IHC Company, Delft University ofTechnology, VostaLMG Company of Holland and Germany, A&M
University of Texas, Army Corps of Engineers, etc. have carried out alot of continuous research and development, all of which are at theleading level in the world. Among them, the cutter suction dredger"Vlaanderen XIX" adopted the reamer with VOSTA T-8 series cutter
teeth. It can cut rocks with compressive strength up to 150 MPa. On theother hand, the study of multi-concentrated high-pressure jet cutting
and erosion, and relatively little research on the mechanism of lightconcrete cutting.

KEY WORDS: High pressure water jet, inclined jet, experimental
research, lightweight concrete

INTRODUCTION
High-pressure water jet cutting technology is an important aspect of theapplication of water jet technology, which is applied in manyengineering fields (Sun, 1992; Li, 1997; Shen, 1998). Other scholars
have also actively explored the Material processing mechanism ofabrasive water jet (Matsumura, 2010; Bui 2017). In dredging
engineering, for example, high-pressure jet can be used to assist thedredging operation of trailing suction dredgers, pre-cut hard clay andimprove the cutting efficiency. However, due to the operating
conditions, the research on rock breaking by high-pressure water jet has
not been studied and applied in the dredging field. The pressure ofhigh-pressure water jet is limited and the working environment, which

Zhang (2003) established the calculation model of rock breaking
process by high-pressure water jet using dynamic contact method. Sun(2005) and others used dynamic nonlinear finite element method andHoffman crushing criterion to study the law of rock crushing by highpressure water jet. Si (2017) also used ALE method to simulate rock3266