State-of-the-art jet trenching analysis in stiff clays

Machin, Jon; Allan, P

doi:10.1201/b10132-129

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…Figure 4 illustrates some of these techniques. [56]) and (b) observed cavity formation along with the fluidization or cutting process (adapted from Machin and Allan [57]).…”

Section: Jetting Approachesmentioning

confidence: 99%

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Perspective Review on Subsea Jet Trenching Technology and Modeling

Njock

Zheng

Zhang

et al. 2020

JMSE

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This paper presents a comprehensive review on subsea jet trenching technology via a critical analysis of its principle, mechanism, devices, modeling approaches, as well as properties of subsea sediments. This review shows that the success of jet trenching operations is closely related to some key factors including the soil conditions, trencher specifications, and characteristics of pipelines or cables. Three case histories are presented to demonstrate the importance of these key factors and their interrelationships. This paper also points out a number of challenges pertaining to the implementation of the jet trenching method in carbonate sediments, as well as some limitations and gaps in the existing modeling approaches. Future perspective researches that are recommended to develop: (1) promising theories, like turbulent submerged flow, and (2) robust numerical approaches, such as the smoothed particle hydrodynamics (SPH) and material point method (MPM) to substantiate the experimental experience and reveal possible hidden mechanisms.

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“…Figure 4 illustrates some of these techniques. [56]) and (b) observed cavity formation along with the fluidization or cutting process (adapted from Machin and Allan [57]).…”

Section: Jetting Approachesmentioning

confidence: 99%

“…Figure 3. General principle of the jet trenching method: (a) Conceptual illustration (adapted from Warringa et al[56]) and (b) observed cavity formation along with the fluidization or cutting process (adapted from Machin and Allan[57]). …”

mentioning

confidence: 99%

Perspective Review on Subsea Jet Trenching Technology and Modeling

Njock

Zheng

Zhang

et al. 2020

JMSE

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“…A careful jet nozzle design will optimize jet stream velocities, minimize energy requirements, and dramatically improve system efficiency (Machin and Allan, 2011). The nozzles used in this test are 138 in cone angle, with the straight portion 2.5 times the size of the diameter.…”

Section: Pump Systemmentioning

confidence: 99%

“…Further work is definitely necessary if the industry wishes to further enhance the capability of jet trencher systems. Additional testing programs and new types of in situ and laboratory testing are likely to be required (Machin and Allan, 2011).…”

Section: Introductionmentioning

confidence: 99%

Experimental Research on Trenching in Stiff Clay by Submerged Vertical Traveling Jets

Zhang

Zhao

et al. 2016

Journal of Coastal Research

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Zhang, S.; Zhao, M.; Ge, T., and Wang, C., 0000. Experimental research on trenching in stiff clay by submerged vertical traveling jets. Journal of Coastal Research, 00(0), 000-000. Coconut Creek (Florida), ISSN 0749-0208. This study investigated trenching by submerged circular traveling jets in stiff clay using an experimental method. The testing clay was prepared as mixtures of natural clay and cement with shear strength ranging from 60 kPa to 90 kPa. The jet pressure, the nozzle translational velocity, and the diameter of the nozzle all varied in the test. A cohesive sediment scouring theory was employed to reveal the mechanism of the jet trenching. It showed that the boundary layer shear force on the jet-soil interface might be the predominant mobilizing force for jet trenching. The trench depth was found to increase with the jet pressure, erodibility coefficient, and the diameter of the nozzle and decrease with the translational velocity of the nozzle and the threshold stress of the clay. The essence of the traveling jet trenching could be considered as jet erosion. The efficiency of jet trenching was found be higher when the jet worked with low pressure and large diameter. The trench depth of a large nozzle could be obtained by testing a small one.ADDITIONAL INDEX WORDS: Subsea pipeline burying, artificial clay, boundary layer shear force, erosion.

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