The bentonite-water mixture was selected as the substitute of seabed sediments according to the in-situ measurement data of sediments 15-20 cm deep in China's ocean poly-metallic mining contract area and the soft ...The bentonite-water mixture was selected as the substitute of seabed sediments according to the in-situ measurement data of sediments 15-20 cm deep in China's ocean poly-metallic mining contract area and the soft seabed sediments could be simulated with certain proportion of the bentonite and water; besides, based on the theory on the interaction between the vehicle and ground and referenced to Bekker's apparatus and related experimental methods, a scenario on the experimental system of the pressure-sinkage characteristics of interaction between the track of tracked vehicle and soft seabed sediments was designed. The pressure-sinkage experiments were performed with different dimensions of penetration plates. The "pressure-sinkage" model based on Bekker's formula and correlation parameters were obtained to describe the corresponding characteristics of the seabed sediments and a smart calibration model on the pressure-sinkage characteristic of the track was established based on the function chain neural network, which could provide boundary loading conditions for simulation analysis of the tracked vehicle moving on the seabed.展开更多
Sediments in the seabed hold vital clues to the study of marine geology,microbial communities and history of ocean life,and the remote operated vehicle(ROV)mounted tubular sampling is an important way to obtain sedime...Sediments in the seabed hold vital clues to the study of marine geology,microbial communities and history of ocean life,and the remote operated vehicle(ROV)mounted tubular sampling is an important way to obtain sediments.However,sampling in the seabed is a particularly difficult and complicated task due to the difficulty accessing deep water layers.The sampling is affected by the sampler’s structural parameters,operation parameters and the interaction between the sampling tube and sediments,which usually results in low volume and coring rate of sediments obtained.This paper simulated the soft viscous seabed sediments as non-Newtonian Herschel-Bulkley viscoplastic fluids and established a numerical model for the tubular sampling based on the volume of fluid(VOF)method.The influence rules of the sampling tube diameter,drainage area rate,penetration velocity,and sediments dynamic viscosity on coring rate and volume were studied.The results showed that coring volume was negatively correlated with all the parameters except the sampling tube diameter.Furthermore,coring rate decreased with increases in penetration velocity,drainage area rate,and sediments dynamic viscosity.The coring rate first increased and then decreased with increasing of the sampling tube diameter,and the peak value was also influenced by penetration velocity.Then,based on the numerical simulation results,an experimental sampling platform was set up and real-world sampling experiments were conducted.The simulation results tallied with the experimental results,with a maximum absolute error of only 4.6%,which verified that the numerical simulation model accurately reflected real-world sampling.The findings in this paper can provide a theoretical basis for facilitating the optimal design of the geometric structure of the seabed sediments samplers and the parameters in the sampling process.展开更多
Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineerin...Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineering challenges.This study establishes a multiscale modelling framework coupling the discrete element method(DEM)with multi-body dynamics(MBD)to investigate track-seabed dynamic interactions across three operational modes:flat terrain,slope climbing,and ditch surmounting.The simulation framework,validated against laboratory experiments,systematically evaluates the influence of grouser geometry(involute,triangular,and pin-type)and traveling speed(0.2–1.0 m/s)on traction performance,slip rate,and ground pressure distribution.Results reveal rate-dependent traction mechanisms governed by soil microstructural responses:higher speeds enhance peak traction but exacerbate slip instability on complex terrain.Critical operational thresholds are established—0.7 m/s for flat terrain,≤0.5 m/s for slopes and ditches—with distinct grouser optimization strategies:involute grousers achieve 35%–40%slip reduction on slopes through progressive soil engagement,while triangular grousers provide optimal impact resistance during ditch crossing with 30%–35%performance improvement.These findings provide quantitative design criteria and operational guidelines for optimizing TMV structural parameters and control strategies,offering a robust theoretical foundation for enhancing the performance,safety,and reliability of deep-sea mining equipment in complex submarine environments.展开更多
Gas-bearing sediments are widely distributed in five continents all over the world.Most of the gases exist in the soil skeleton in the form of discrete large bubbles.The existence of gas-phase may increase or decrease...Gas-bearing sediments are widely distributed in five continents all over the world.Most of the gases exist in the soil skeleton in the form of discrete large bubbles.The existence of gas-phase may increase or decrease the strength of the soil skeleton.So far,bubbles’structural morphology and evolution characteristics in soil skeleton lack research,and the influence of different gas reservoir pressures on bubbles are still unclear.The micro characteristics of bubbles in the same sediment sample were studied using an industrial CT scanning test system to solve these problems.Using the image processing software,the micro variation characteristics of gas-bearing sediments in gas reservoir pressure change are obtained.The results show that the number and volume of bubbles in different equivalent radius ranges will change regularly under different gas reservoir pressure.With the increase of gas reservoir pressure,the number and volume of tiny bubbles decrease.In contrast,the number and volume of large bubbles increase,and the gas content in different positions increases and occupies a dominant position,driving the reduction of pore water and soil skeleton movement.展开更多
In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environ...In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environment. Field tripod observations conducted in the Jiaozhou Bay in China are reported, to investigate the effects of hydrodynamic conditions on the erosion and resuspension processes of the seabed. The observational results show that the maximum shear stress created by tidal currents can reach 0.35 N/m2, which is higher than the wave-induced shear stress during fair weather conditions. A seabed erosion frequently occurs during the flood tide, whereas a seabed deposition occurs during ebb tide. Waves can produce a bottom shear stress approximately equivalent to that induced by currents when the local wind reaches Force 4 with a speed of 5 m/s.When the wind reaches 7 m/s and the significant wave height reaches 26 cm, waves play a more significant role than currents in the dynamic processes of the seabed sediment resuspension and lead to a high value of turbidity that is approximately two to eight times higher than that in fair weather. These analyses clearly illustrate that periodic current-induced sediment erosion and resuspension are dominant in fair weather, whereas episodic high waves are responsible for significant sediment resuspension. Additional work is needed to establish a more thorough understanding of the mechanisms of sediment dynamics in the Jiaozhou Bay.展开更多
Seabed sediment recognition is vital for the exploitation of marine resources.Side-scan sonar(SSS)is an excellent tool for acquiring the imagery of seafloor topography.Combined with ocean surface sampling,it provides ...Seabed sediment recognition is vital for the exploitation of marine resources.Side-scan sonar(SSS)is an excellent tool for acquiring the imagery of seafloor topography.Combined with ocean surface sampling,it provides detailed and accurate images of marine substrate features.Most of the processing of SSS imagery works around limited sampling stations and requires manual interpretation to complete the classification of seabed sediment imagery.In complex sea areas,with manual interpretation,small targets are often lost due to a large amount of information.To date,studies related to the automatic recognition of seabed sediments are still few.This paper proposes a seabed sediment recognition method based on You Only Look Once version 5 and SSS imagery to perform real-time sedi-ment classification and localization for accuracy,particularly on small targets and faster speeds.We used methods such as changing the dataset size,epoch,and optimizer and adding multiscale training to overcome the challenges of having a small sample and a low accuracy.With these methods,we improved the results on mean average precision by 8.98%and F1 score by 11.12%compared with the original method.In addition,the detection speed was approximately 100 frames per second,which is faster than that of previous methods.This speed enabled us to achieve real-time seabed sediment recognition from SSS imagery.展开更多
基金Project(11JJ3059) supported by Natural Science Foundation of Hunan Province, ChinaProject(2010GK3091) supported by Science and Technology Industrial Support Program of Hunan Province, China+1 种基金Project(10B058) supported by Excellent Youth Foundation of Education Department of Hunan Province, ChinaProject(51105386) supported by the National Natural Science Foundation of China
文摘The bentonite-water mixture was selected as the substitute of seabed sediments according to the in-situ measurement data of sediments 15-20 cm deep in China's ocean poly-metallic mining contract area and the soft seabed sediments could be simulated with certain proportion of the bentonite and water; besides, based on the theory on the interaction between the vehicle and ground and referenced to Bekker's apparatus and related experimental methods, a scenario on the experimental system of the pressure-sinkage characteristics of interaction between the track of tracked vehicle and soft seabed sediments was designed. The pressure-sinkage experiments were performed with different dimensions of penetration plates. The "pressure-sinkage" model based on Bekker's formula and correlation parameters were obtained to describe the corresponding characteristics of the seabed sediments and a smart calibration model on the pressure-sinkage characteristic of the track was established based on the function chain neural network, which could provide boundary loading conditions for simulation analysis of the tracked vehicle moving on the seabed.
基金Supported by National Key R&D Program of China(Grant No.2016YFC0300502)the National Natural Science Foundation of China(Grant Nos.51705145 and 517779092)+1 种基金Scientific Research Fund of Hunan Provincial Education Department(Grant No.18B205)Hunan Province Natural Science Foundation(Grant No.2019 JJ50182).
文摘Sediments in the seabed hold vital clues to the study of marine geology,microbial communities and history of ocean life,and the remote operated vehicle(ROV)mounted tubular sampling is an important way to obtain sediments.However,sampling in the seabed is a particularly difficult and complicated task due to the difficulty accessing deep water layers.The sampling is affected by the sampler’s structural parameters,operation parameters and the interaction between the sampling tube and sediments,which usually results in low volume and coring rate of sediments obtained.This paper simulated the soft viscous seabed sediments as non-Newtonian Herschel-Bulkley viscoplastic fluids and established a numerical model for the tubular sampling based on the volume of fluid(VOF)method.The influence rules of the sampling tube diameter,drainage area rate,penetration velocity,and sediments dynamic viscosity on coring rate and volume were studied.The results showed that coring volume was negatively correlated with all the parameters except the sampling tube diameter.Furthermore,coring rate decreased with increases in penetration velocity,drainage area rate,and sediments dynamic viscosity.The coring rate first increased and then decreased with increasing of the sampling tube diameter,and the peak value was also influenced by penetration velocity.Then,based on the numerical simulation results,an experimental sampling platform was set up and real-world sampling experiments were conducted.The simulation results tallied with the experimental results,with a maximum absolute error of only 4.6%,which verified that the numerical simulation model accurately reflected real-world sampling.The findings in this paper can provide a theoretical basis for facilitating the optimal design of the geometric structure of the seabed sediments samplers and the parameters in the sampling process.
基金financially supported by the National Key Research and Development Program of China-Young Scientist Project(No.2024YFC2815400)the National Natural Science Foundation of China(No.52588202).
文摘Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineering challenges.This study establishes a multiscale modelling framework coupling the discrete element method(DEM)with multi-body dynamics(MBD)to investigate track-seabed dynamic interactions across three operational modes:flat terrain,slope climbing,and ditch surmounting.The simulation framework,validated against laboratory experiments,systematically evaluates the influence of grouser geometry(involute,triangular,and pin-type)and traveling speed(0.2–1.0 m/s)on traction performance,slip rate,and ground pressure distribution.Results reveal rate-dependent traction mechanisms governed by soil microstructural responses:higher speeds enhance peak traction but exacerbate slip instability on complex terrain.Critical operational thresholds are established—0.7 m/s for flat terrain,≤0.5 m/s for slopes and ditches—with distinct grouser optimization strategies:involute grousers achieve 35%–40%slip reduction on slopes through progressive soil engagement,while triangular grousers provide optimal impact resistance during ditch crossing with 30%–35%performance improvement.These findings provide quantitative design criteria and operational guidelines for optimizing TMV structural parameters and control strategies,offering a robust theoretical foundation for enhancing the performance,safety,and reliability of deep-sea mining equipment in complex submarine environments.
基金The Shandong Joint Funds of National Natural Science Foundation of China under contract No.U2006213the Fundamental Research Funds for the Central Universities under contract No.201962011the Grant of Laboratory for Marine Geology,Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.MGQNLM-KF201804。
文摘Gas-bearing sediments are widely distributed in five continents all over the world.Most of the gases exist in the soil skeleton in the form of discrete large bubbles.The existence of gas-phase may increase or decrease the strength of the soil skeleton.So far,bubbles’structural morphology and evolution characteristics in soil skeleton lack research,and the influence of different gas reservoir pressures on bubbles are still unclear.The micro characteristics of bubbles in the same sediment sample were studied using an industrial CT scanning test system to solve these problems.Using the image processing software,the micro variation characteristics of gas-bearing sediments in gas reservoir pressure change are obtained.The results show that the number and volume of bubbles in different equivalent radius ranges will change regularly under different gas reservoir pressure.With the increase of gas reservoir pressure,the number and volume of tiny bubbles decrease.In contrast,the number and volume of large bubbles increase,and the gas content in different positions increases and occupies a dominant position,driving the reduction of pore water and soil skeleton movement.
基金The National Natural Science Foundation of China under contract Nos 41402253,41427803 and 41372287the Project of Qingdao National Laboratory for Marine Science and Technology under contract No.QNLM2016ORP0110
文摘In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environment. Field tripod observations conducted in the Jiaozhou Bay in China are reported, to investigate the effects of hydrodynamic conditions on the erosion and resuspension processes of the seabed. The observational results show that the maximum shear stress created by tidal currents can reach 0.35 N/m2, which is higher than the wave-induced shear stress during fair weather conditions. A seabed erosion frequently occurs during the flood tide, whereas a seabed deposition occurs during ebb tide. Waves can produce a bottom shear stress approximately equivalent to that induced by currents when the local wind reaches Force 4 with a speed of 5 m/s.When the wind reaches 7 m/s and the significant wave height reaches 26 cm, waves play a more significant role than currents in the dynamic processes of the seabed sediment resuspension and lead to a high value of turbidity that is approximately two to eight times higher than that in fair weather. These analyses clearly illustrate that periodic current-induced sediment erosion and resuspension are dominant in fair weather, whereas episodic high waves are responsible for significant sediment resuspension. Additional work is needed to establish a more thorough understanding of the mechanisms of sediment dynamics in the Jiaozhou Bay.
基金funded by the Natural Science Foundation of Fujian Province(No.2018J01063)the Project of Deep Learning Based Underwater Cultural Relics Recognization(No.38360041)the Project of the State Administration of Cultural Relics(No.2018300).
文摘Seabed sediment recognition is vital for the exploitation of marine resources.Side-scan sonar(SSS)is an excellent tool for acquiring the imagery of seafloor topography.Combined with ocean surface sampling,it provides detailed and accurate images of marine substrate features.Most of the processing of SSS imagery works around limited sampling stations and requires manual interpretation to complete the classification of seabed sediment imagery.In complex sea areas,with manual interpretation,small targets are often lost due to a large amount of information.To date,studies related to the automatic recognition of seabed sediments are still few.This paper proposes a seabed sediment recognition method based on You Only Look Once version 5 and SSS imagery to perform real-time sedi-ment classification and localization for accuracy,particularly on small targets and faster speeds.We used methods such as changing the dataset size,epoch,and optimizer and adding multiscale training to overcome the challenges of having a small sample and a low accuracy.With these methods,we improved the results on mean average precision by 8.98%and F1 score by 11.12%compared with the original method.In addition,the detection speed was approximately 100 frames per second,which is faster than that of previous methods.This speed enabled us to achieve real-time seabed sediment recognition from SSS imagery.
