Abstract:Based on summarizing the development achievements and problems of the 14th Five-Year Plan,the ideas and countermeasures for promoting high-quality development of the Yangtze Estuary waterway during the 15th Five-Year Plan period are prospected.The results show that the Yangtze Estuary waterway urgently needs to systematically enhance its overall throughput capacity and safety resilience level during the 15th Five-Year Plan period,which is a crucial stage for China to accelerate the construction of a strong transportation country and improve the modern inland waterway transportation system.In this regard,the high-quality development ideas and countermeasures for the waterway are proposed during the 15th Five-Year Plan period,mainly including:1)Focus on enhancing resilience and accelerate the construction of a modern waterway facility system.2)Highlight the improvement of quality and efficiency,and enhance the system of waterway maintenance and protection.3)Emphasize the empowerment of new quality productivity,and deepen the innovation and application system of waterway technology.4)Increase support and guarantee,and improve the system of waterway supporting facilities and equipment.5)Adhere to bottom-line thinking,and build a solid system of navigation safe and green development.At the same time,it is also recommended to take active actions in seizing the favorable opportunities for estuarine protection and regulation,increasing financial and ecological support,and strengthening collaborative management and integrated development among all parties within the jurisdictional water area.It can comprehensively enhance the navigation management system and modernization level of the Yangtze Estuary waterway,which will provide useful ideas and references for China to explore the construction practice of world-class estuarine navigation channel.

Abstract:With the vigorous development of science and technology,the level of waterway maintenance and management in our country has been significantly enhanced.Under the new pattern of the comprehensive advancement of the “four verticals,four horizontals and two networks”,in response to the uneven development of waterway management and maintenance technology in our country,the current status of waterway management and maintenance technology development in each region during the 14th Five-Year Plan period is systematically sorted out,and the development situation and core demands of waterway management and maintenance technology during the 15th Five-Year Plan period are studied.By combining case analysis and data induction,it is shown that different innovative management and maintenance technologies have been explored and practiced in various river basins and regions across the country,but a system and standard have not yet been formed,and the overall level still needs to be improved.Facing the 15th Five-Year Plan period,the integration of intelligence and digitalization should be taken as the main line,green and low-carbon transformation as the orientation,and the improvement of the standardization system as the support.The full life cycle management model should be comprehensively popularized,and scientific and technological innovation and application research in key areas such as safety risk prevention and control,intelligent prevention and early warning,and efficient emergency response should be deepened,so as to enhance the efficiency and sustainability of waterway management and maintenance.

Abstract:In response to the issue of vessel collision damage in China’s ship lock operations,a comparative study is conducted on the calculation methods of ship impact forces through systematic literature reviews of domestic and international sources,covering aspects such as normative formulas,model tests,and numerical simulations.The results indicate that under specific working conditions (ship speed of 1 m/s,angle of 3°-4°),the calculation results from the JTJ 307-2001 Code for Design of Hydraulic Structures of Shiplocks are roughly similar to those from the JTG D60-2015 General Specifications for Design of Highway Bridges and Culverts and Wang Junjie’s global mean formula.However,for larger ship speeds and impact angles,the results are underestimated.The calculation results of the modified Woisin formula are closest to the existing experimental,though the elevated experimental values require further verification for reliability.In comparison,calculation values of the American Association of State Highway and Transportation Officials (AASHTO) Guide Specification and Commentary for Vessel Collision Design of Highway Bridges are close to most numerical simulation results,and its expression aligns most closely with the quantitative relationship revealed by existing research between the impact force of ships passing through ship locks and factors such as ship mass and speed.The standard used in the numerical simulations in existing literature are different,resulting in significant differences in the magnitudes of the ship impact forces.It is suggested that the numerical simulation method for ship-lock collisions is standardized.

Abstract:Regarding wharf dike improved by wall-type deep cement mixing(DCM),there are significant differences between design methods in Chinese and American codes,yet existing research lacks comprehensive comparisons.On the basis of this issue,a comparative analysis is conducted using engineering case.The results show that the in-situ shear strength of cement-treated soil under American code is 34.8% higher than that under Chinese code.For DCM composite soil with a 50% replacement ratio,the American standard accounts for the influence of the site variability coefficient,resulting in shear strengths that are 22.6% higher than Chinese code when calculating circular slip stability,and 46.8% higher for other failure modes.When applying Chinese code to calculate DCM stability and strength,additional consideration of the vertical shear force from the soil on the active earth pressure side and the horizontal confining pressure at the toe can increase the anti-overturning stability factor by 5.7%,reduce the toe compressive stress by 7.8%,and increase the toe compressive strength by 29.6%.In Chinese code,the method of taking the vertical resultant force at the toe for wall-type DCM foundation bearing capacity calculation is unreasonable.The allowable vertical stress at the toe should be adopted,considering appropriate resistance partial factors.When calculating the vertical shear stress in the DCM body,the influence of eccentricity in the vertical resultant force at the base should be considered.In designing longitudinal walls to prevent soil extrusion between walls,refined specifications can be provided.

Abstract:To address the reduced accuracy of structural condition identification caused by the coupled interference of temperature and mechanical loading in pile-supported wharves,an automatic thermo-mechanical separation approach is developed.The method combines complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and K-means clustering,and constructs a multi-feature vector integrating spectral kurtosis,modal energy,and sample entropy to automatically classify and reconstruct intrinsic mode functions (IMFs).Field data from a representative pile foundation at the Ningbo-Zhoushan Port are used for validation.The results indicate that the separated temperature component correlates highly with the measured temperature (PCC＞0.89),and the mechanical component achieves a signal-to-noise ratio improvement of over 12 dB.Compared with the EEMD-K-means and VMD-K-means models,the proposed method reduces the root mean square error by approximately 12% and improves the accuracy of temperature-trend extraction by 4%.Without relying on reference fibers or finite element simulations,the method stably separates thermal and mechanical responses and accurately identifies berthing events under complex marine conditions.The findings clarify the thermo-mechanical coupling behavior of pile foundations and provide an efficient and scalable signal-processing technique for health monitoring of port structures.

Abstract:To address the challenges of numerous piles and columns,complex modeling,and lengthy computation times in actual wharf engineering projects,we innovatively employ three-dimensional sediment transport model to investigate the local scour characteristics of typical pile-column groups under different arrangements,reveal the scour depth,extent,and local velocity changes within pile-column clusters,and verify by single-column local scour results.The simulations of different pile-column configurations demonstrate distinct differences in scour depth and morphology among single column,double columns,and pile-column groups.As the number of pile-columns increases,local scour depth gradually decreases while scour patterns become more uniform.Under high flood conditions,significant local scouring (3.30-4.31 m) occurs at the pier columns of the wharf approach bridge (twin columns aligned with the flow),particularly pronounced in the inter-column zones.The scour around the wharf platform piles (a typical pile cluster) is relatively uniform (2.5-4.0 m),though high-velocity zones may intensify scouring.The typical three-pile cluster exhibited shallower scour,effectively reducing the scour depth of the main piles.Rational placement of fender piles can significantly reduce both the scour extent and depth.The findings on local flow velocities,scour depth,and extent under high flood conditions provide a basis for determining design parameters such as rock size and protection range for pile column protection in the middle and lower reaches of the Yangtze River.

Abstract:To address the challenge of difficult recovery of subsea structures on sandy coasts caused by excessive anchoring force,the experimental research on the anchoring bearing capacity of subsea structures is conducted in this paper.A simplified experimental device model of subsea structures is built to simulate the anchoring-lifting and anchoring-overturning processes in a sandy coastal environment.The control variable method is adopted to adjust the anchoring depth and total mass of the structure,while high-precision measuring equipment is used to collect anchoring bearing capacity data.On the basis of the experimental data,a multiple linear regression model is applied to quantify the influence rule of anchoring depth and total structural mass on the bearing capacity.The results indicate that both anchoring depth and total structural mass have a positive impact on vertical and lateral bearing capacities,showing an approximately linear relationship.The regression models exhibit good fitting performance,with the coefficient of determination R2 being 0.904 for the vertical bearing capacity model and 0.974 for the lateral bearing capacity model.In anchoring design,it is suggested that on the premise of ensuring the anti-overturning performance of the structure,the anchoring depth and total structural mass should be reasonably determined to balance anti-overturning performance and recoverability.

Abstract:In response to the vulnerable problem of high-piled wharf pile foundations in marine environments,although steel sleeve grouting technology has the potential for reinforcement,the bending design lacks theoretical support.Through experiments and theoretical modeling,the research aims to reveal its mechanical properties and failure mechanisms,propose quantitative calculation methods,and support the improvement of engineering safety.The experiment used four different parameters of steel sleeve grouting reinforcement PHC pipe pile specimens,with key variables including grouting material thickness (40,50,60 mm) and steel sleeve thickness (5,8 mm).Through graded loading and monitoring of the load-strain response,the results indicate that increasing the thickness of both the grouting material and the steel sleeve can improve the flexural performance,and the strengthening effect of the steel sleeve thickness is more significant.Furthermore,the calculation formula for flexural bearing capacity is derived based on the plane section assumption.Experimental verification shows that the error is only 2.16%-6.58%,indicating satisfactory reliability.The research results provide a theoretical basis and quantitative calculation method for the application of steel sleeve grouting technology in the flexural design of pile foundations,which has important reference value for improving the safety and accuracy of the repair and reinforcement of high-piled wharves and similar engineering structures.

Abstract:To the severe corrosion and maintenance challenges observed in the roof steel structures of the silos during the operation of Phase III and IV of the Huanghua Port Coal Terminal,this study conducts anticorrosion research on these structures.The objective is to propose long-term anticorrosion solutions suitable for the highly corrosive port environment,extending the service life of protective coatings and reducing future maintenance frequency.Through field investigations and theoretical analysis,the primary causes of severe corrosion in the roof steel structures are identified.Based on literature review and engineering case studies,metal protection and coating protection technologies are extensively evaluated,leading to the proposal of two heavy-duty anticorrosion schemes with a design service life of no less than 30 years.Furthermore,addressing the compatibility between anticorrosion and fire protection,theoretically grounded and practical engineering case studies are employed to propose integrated anticorrosion and fire protection measures suitable for port silos.In response to the highly corrosive environment of ports,heavy-duty anticorrosion measures and anticorrosion and fire prevention supporting measures are proposed,which can increase the design life of conventional anti-corrosion protection from 10 years to 30 years,with an extension of three times.The research results can provide valuable references for the anti-corrosion design of Phase V of the Huanghua Port Coal Terminal and other similar silo structures.

Abstract:Addressing the enclosure methods for belt conveyors in dry bulk ship loading and unloading terminals,this study analyzes the applicability of existing enclosure solutions based on typical conveyor layouts.The results indicate that conventional solutions,such as fully enclosed cover belts and enclosed galleries,are often constrained by complex equipment structures when belt conveyors are arranged between the rails of loading and unloading equipment,making it difficult to simultaneously ensure enclosure effectiveness and operational reliability.To address these issues,a novel dynamic enclosure system for quay belt conveyors is proposed.The system distinguishes the loaded section from the unloaded section of the belt conveyor and applies enclosure only to the loaded section.A belt winding device is adopted to realize dynamic winding and releasing of the cover belt in synchronization with the movement of loading and unloading equipment.Based on different layout conditions of ship loaders and unloaders,the working principle,structural configuration and engineering applicability of the proposed system are analyzed.The results indicate that this solution is suitable for bulk cargo loading and unloading terminals where the belt conveyors are positioned between the two tracks of loading and unloading equipment,and it is feasible for engineering promotion and application.

Abstract:To address the problems of high cracking risk caused by hydration heat during construction,low construction efficiency,and serious pollution from wet operations associated with traditional cast-in-place navigation walls of ship locks,this paper investigates the structural design and mechanical performance of fully assembled navigation walls for ship locks in mountainous rivers.A fully prefabricated assembly scheme using high-strength bolts for intra-layer connections and longitudinal anchor bars for inter-layer connections is adopted.A layered assembly method based on 4 m×2 m×2.4 m modular standard components is established,together with design methods for the shear mechanism of intra-layer bolts and the anti-slip mechanism of inter-layer anchor bars.A three-dimensional nonlinear finite element model is developed to investigate the structural stress and deformation,contact state,and performance of connectors under operation at high water level,operation at low water level,completion condition,and check condition.Results show that the maximum slip between assemblies is 1.07 mm,and the maximum principal stress of bolts is 215.30 MPa,which is below the yield strength of 300 MPa.Local yielding occurs in anchor bar bundles,but the structural integrity is favorable.The anti-sliding stability safety factor ranges from 1.15 to 1.45,satisfying the code limits.The study indicates that fully prefabricated navigation walls possess good mechanical properties and engineering applicability in ship locks of mountainous rivers.

Abstract:Under the emergency valve closing condition of high-head ship locks,the water delivery valves close slowly under self-weight,which may result in over-filling or over-discharging in multi-stage ship locks or excessive reverse water head in single-stage ship locks.Excessively fast closing,with a high velocity maintained near the fully closed position,may damage the bottom water seal and even cause failure of the hydraulic structure.To address the difficulty in controlling the emergency closing speed of water delivery valves in high-head ship locks under unpowered conditions,this paper analyzes the feasibility of emergency closing under UPS-powered operation and fully unpowered manual operation,designs an emergency system for the unpowered closing of water delivery valves,and verifies its effectiveness through field tests.This system adds a set of poppet-type solenoid directional valves to the hydraulic system of the ship lock valve,connecting the rod and rodless chambers of the valve cylinder to form a differential circuit.A UPS power supply is used to power the valve group.By actuating different numbers of solenoid directional valves,the lowering speed of the valve under self-weight can be adjusted,solving the problem that the existing hydraulic system cannot realize rapid valve closing when the ship lock is completely powered off.Field prototype tests on the ship lock demonstrate that the proposed scheme features high closing reliability and adjustable closing speed.

Abstract:With the growth of waterway transportation,traditional channel inspection methods struggle to meet the need for efficiency and precision,especially in complex environments for navigation aids.In view of the above problem,this paper proposes an intelligent navigation aids recognition method based on unmanned aerial vehicle and artificial intelligence.The method integrates an improved YOLOv7 model,convolutional block attention module attention mechanism,and MobileViT lightweight structure to address low small target detection accuracy and high background interference in complex aquatic environments during the day.In the nighttime,hue-saturation-value color space segmentation and time-series analysis techniques effectively extract navigation aid light flicker cycles and mitigate multi-source light interference.The experimental results show that the improved model achieves an average precision of 0.99 and an average confidence of 0.97,while nighttime recognition accuracy reaches 97.1%,significantly outperforming traditional methods.Additionally,the exchangeable image file format-based pose information geometric mapping model enables high-precision conversion from image coordinates to geographic coordinates,enhancing location accuracy.The proposed method operates stably in dynamic environments and provides effective technical support for the intelligent operation and maintenance of inland waterway navigation aids,offering substantial engineering application value.

Abstract:Aiming at the problem that the upstream approach channel of Yanzhou Hub Ship Lock renovation project cannot be arranged as a straight and fully sheltered approach channel due to flood discharge,ecological protection,and river regime constraints,physical model tests are used to study the navigable flow conditions of the upstream zigzag non-sheltered approach channel.A 1:100 scale physical model is developed to analyze the navigable flow conditions in the approach channel.The conclusions indicate that:1) Although the fully sheltered long guide wall scheme meets the navigable flow condition requirements,the flow velocity at the 15 m gap reaches 5.23 m/s,causing serious local scouring.2)Without lowering the navigation standards for ships entering and leaving the lock,a proposal combining hydrological statistical analysis suggests setting separate berthing sections for the medium-dry season and the flood season.During the medium-dry season (Q≤2,500 m3/s),the maximum flow velocity in the berthing section is 0.50 m/s,which meets the code requirements.During the flood season (Q ＞2,500 m3/s),the maximum transverse velocity in the entrance area is 0.44 m/s,the maximum longitudinal velocity is 1.23 m/s,the maximum transverse velocity in the connecting section is 0.21 m/s,and the maximum longitudinal velocity is 1.79 m/s,all of which satisfy the code requirements.Furthermore,by the use of the upstream anchorage for vessel waiting area,and comprehensively considering the number of affected days and information-based scheduling methods,the impact on ship navigation capacity is limited.The research results can provide a reference for similar non-sheltered ship lock approach channels.

Abstract:To determine the optimal layout scheme for the regulation buildings in the South Passage of the Yangtze Estuary and achieve effective regulation outcomes,this paper employs a three-dimensional sediment-water mathematical model to systematically compare and optimize the layout of these buildings.On the basis of the complex hydrodynamic and sediment transport characteristics of the South Passage alongside its riverine conditions,this paper follows a regulation approach concentrated on “bank protection,channel stabilization,flow diversion,and sediment retention”,and designs a multi-stage comparison and selection process.Starting from the initial scheme,the NCG1A scheme restricted flow in the lower section of the Jiangya North Channel is identified as the preferred option.Subsequent comparisons of different scheme configurations reveal that eliminating the north and south jetty clusters while optimizing only the diversion embankment axis offers greater advantages in enhancing main channel dynamics,ensuring navigation safety,and minimizing environmental impact.Further refinement of embankment elevation and length determine that a crest elevation of 2.0 m yields optimal channel regulation,with the embankment length optimized to 24.4 km.Scheme NCG5 effectively enhances the ebb-tide dynamics of the southern main channel while minimizing impacts on the adjacent northern deep-water channel and Jiuduansha Nature Reserve.This achieves synergistic multi-objective coordination of navigation channel management effectiveness,navigational safety,engineering economics,and ecological conservation,providing valuable insights for similar estuary regulation projects.

Abstract:To address the issue of the formation of connected funnel vortices in the upper approach channel during the ship lock inlet filling process,which adversely affects the inlet and chamber water delivery conditions and deteriorates valve operation,a three-dimensional numerical simulation of the ship lock’s water intake process is conducted using the RNG(renormalization group) k-ε turbulence model.The study focuses on the hydraulic characteristics,including flow velocity and vortex evolution at the ship lock inlet.The results indicate that when the inflow area of the top grid at the inlet is 139.8 m2,the maximum surface flow velocity during the inflow process is 1.6 m/s,and a distinct interconnected funnel vortex is formed at the inlet.When the inlet flow area is increased by 26.95%,the maximum surface flow velocity decreases by 6.25%,effectively slowing the formation of connected funnel vortices at the inlet.When the inlet flow area is increased by 39.86%,the maximum surface flow velocity decreases by 12.5%,and no significant vortex connection occurs at the inlet.By increasing the total net width of the inlet at the lock head side pier and further expanding inflow area of the top grille,the flow pattern can be effectively stabilized,the flow velocity reduced,and the formation of connected funnel vortices slowed.This reduces the operating load on the valves and thereby improves the water delivery efficiency of the ship lock.

Abstract:To reveal the evolution law of navigation operations at the Three Gorges Hub,this study systematically analyzes its operational characteristics from the aspects of shipping throughput,number of passing vessels,lock operation times,navigation availability rate,and tonnage of vessels passing through the locks.On this basis,combined with historical shipping and regional economic data,dummy variables reflecting the impact of sudden events such as the COVID-19 pandemic are introduced to construct a multiple linear regression model for forecasting future shipping throughput.The results indicate that since the commencement of navigation,the annual growth rate of shipping throughput at the Three Gorges has reached as high as 16.6%,and slowed notably to 3.6% after 2011.The ratio of upstream to downstream throughput has gradually evolved from 3:7 in 2004 to approximately 5:5 in recent years.The shipping hinterland is concentrated in six provinces and municipalities,namely Chongqing,Jiangsu,Hubei,Sichuan,Shanghai and Anhui.The operation efficiency of the ship locks has been continuously improved,with a navigation availability rate stably above 93%,more than 11,000 lockages per year,and an average tonnage per lockage exceeding 22,000 tonnes.The locks have been operating in a state of high efficiency and full load,with their passing capacity approaching the limit.Model predictions show that shipping throughput will reach 267 million tonnes by 2035,which is consistent with the forecast range of 240-290 million tonnes for the proposed Three Gorges New Waterway,demonstrating the urgent need to accelerate its construction.The research findings can provide a reference for navigation issues of the Three Gorges and other similar large-scale navigation hubs.

Abstract:Addressing navigation-obstructing problems of significant annual siltation and unstable navigation channels in key waterways like Fujiangsha and Kouanzhi along the 12.5-m deep-water channel below Nanjing in the Yangtze River,we utilize the field topographic and sediment data from 2022 to 2024,multibeam bathymetry,and a two-dimensional sediment transport model to analyze channel evolution characteristics and evaluate dynamic maintenance dredging effectiveness.We elaborate on the implementation process and technical advantages of the integrated“monitoring-analysis-dredging-evaluation”dynamic maintenance approach.The results indicate that the introduction of a dynamic dredging strategy,which combines multibeam high-frequency scanning with model predictions,enables precise identification and timely dredging of critical sedimentation zones,enhancing maintenance efficiency by about 15%.The total dredging volume in Fujiangsha waterway decreases from 10.267 million m3 in 2022 to 7.301 million m3 in 2024,a reduction of 28.8%,while Kouanzhi waterway’s volume fluctuats from 5.798 million m3 to 7.096 million m3,with a significant increase in the Manyusha section due to special hydrological conditions.The error between the predicted values of the model and the measured values is less than 15%,verifying method reliability.Integrating intelligent monitoring with precision dredging in a proactive maintenance strategy effectively enhances navigation stability and maintenance cost-effectiveness,providing technical support for efficient maintenance of the Yangtze River’s golden waterway.

Abstract:Following the straightening of a curved river channel at a navigation-power hub,the upstream approach channel formed a large oblique angle with the main stream,which posed significant safety risks to vessel passage.To address this issue,an integrated engineering physical model is developed to systematically investigate the navigational flow conditions in the upstream approach channel and its connecting section.Experimental results show that under the original design scheme,the transverse flow velocities in the entrance zone and connecting section of the upstream approach channel substantially exceeds the limits stipulated in relevant standards.This necessitated the implementation of engineering modifications to optimize the flow conditions.Through comparative analysis of multiple proposed schemes,the study examine the flow structures and velocity distribution patterns of the upstream approach channel and its connecting section under different intervention measures.An integrated set of measures is identified,including localized excavation,lateral repositioning of the lock,and optimization of the guidance segment geometry,length,and width of the approach channel.These modifications effectively reduce the peak transverse flow velocity from 0.61 m/s in the original scheme to 0.28 m/s,significantly enhancing the navigational flow conditions in the upstream approach channel and its connecting section,thereby improving vessel navigation safety.The methodology and findings may provide valuable reference for similar engineering projects.

Abstract:To address the insufficient safety margins caused by traditional control methods for inland curved waterways,which are limited to precise centerline tracking and neglect key navigation practices such as“holding high and taking low”,a ship rudder-propeller coordinated control method integrating this good seamanship is proposed.The method features an improved LOS(line-of-sight)guidance law at the guidance layer.It algorithmically implements“holding high and taking low”by introducing a lateral offset,calculated based on operational conditions like vessel speed and current,to proactively generate a strategic,off-centerline reference trajectory.Furthermore,its adaptive integral mechanism effectively compensates for environmental disturbances and eliminates steady-state errors.The control layer employs a conventional PID (proportional-integral-derivative)controller for precise control of the rudder angle,forming a complete rudder-propeller coordinated control system.Simulation results verify that under a 2 m/s cross-current disturbance,the proposed method successfully executes the predetermined strategy,increasing the minimum safety distance to the concave bank by 34.4% compared with traditional methods and exhibiting superior robustness.The research confirms that the method effectively integrates navigation practice with modern control theory,providing a new solution for enhancing the navigational safety of ships in complex and confined waterways.

Abstract:The new Funan Techo Canal in Cambodia’s low-lying Mekong Delta faces significant salinity intrusion,threatening agricultural irrigation on both banks of the river.It is necessary to assess the extent and distribution of saltwater intrusion of the newly constructed canal and propose effective countermeasures.The three-dimensional hydrodynamic-salinity model of Funan Techo Canal is built using MIKE3 to systematically analyze saltwater intrusion patterns both without mitigation and with the operation of a ship lock.The results indicate that salinity intrusion is primarily driven by tidal dynamics and density gradients.The maximum intrusion distance of the 1 psu isohaline exhibits an inverse logarithmic relationship with the upstream freshwater discharge.At a low inflow Q=1 m3 /s,the 1 psu saltwater intrudes up to 25.2 km,this distance is significantly reduced to 12.5 km when the inflow increases to Q=20 m3 /s.The implementation of a ship lock can control upstream water levels and follow specific gate operation sequences to block seawater effectively.It markedly suppresses the intrusion distance and reduces salinity concentrations.After six months of ship lock operation,the 1 psu intrusion distance is limited to just 6.6 km,and the salinity at the lock head decreases from 27 psu to 5.5 psu.Therefore,the ship lock is identified as the key engineering measure for salinity control.Its operation,combined with upstream water level and flow regulation,can synergistically ensure the security of freshwater resources along the canal.

Abstract:To systematically address navigation safety issues arising from adverse flow patterns such as cross-flow,recirculating flow,boil vortices,and overtopping flow in the Changshou waterway of the upper Yangtze River,a movable-bed physical model test is conducted to predict and evaluate the effects of the navigation regulation project.Based on the natural flow and sediment processes from May 2018 to November 2019,model calibration and scale determination are completed,and a high-precision flow-sediment physical model is established.To systematically analyze the response of flow structure and riverbed topography after project implementation,simulations are conducted for four characteristic discharges during flood,medium and dry water periods as well as under typical hydrological year conditions.Results indicate that after regulation,the flow velocity in the central part of Xiaojiashipan decreases by 29.9%,and the maximum flow velocity in the dredged area increases by 34.2%.The angle between the oblique flow in the left branch and the navigation channel is reduced from 39° to 4°,the transverse velocity decreases by more than 85%,and the adverse flow patterns such as boil vortices and overtopping flow are significantly weakened.After scouring and adjustment over a sequence of hydrological years,the riverbed tends to be stable.The left branch navigation channel maintains a designed water depth of 4.5 m,and its width is expanded from less than 110 m to more than 150 m,resulting in significantly improved navigation conditions.The study confirms that the project effectively optimizes the flow patterns and channel dimensions in the rapid reach,and the relevant methods and conclusions can provide theoretical and technical support for the regulation of similar mountainous waterways.

Abstract:This study addresses the threat posed by surge waves induced by the collapse of unstable rock masses along the bank zone of the Three Gorges Reservoir to navigation facilities and ship safety.A fully coupled analysis covering the entire chain of “rock mass entering water-surge wave propagation-ship response” is carried out.Taking the Diaozui dangerous rock mass in the Fengjie section and the surrounding pontoon terminal-moored Yangtze River ship system as the research objects,a three-dimensional numerical simulation method is adopted to simulate the processes of dangerous rock collapse into water,surge wave generation and propagation.The motion response characteristics of the pontoon and moored Yangtze River ships under the action of surge waves are analyzed,and the laws of surge wave generation and propagation induced by the Diaozui dangerous rock,the motion response characteristics of the mooring system,and its safety status are summarized.The results show that the rock collapse and water entry process lasted only 16 seconds,with an initial wave height of 26.4 m.The surge attenuated significantly in the core zone due to energy dispersion,riverbed resistance and other factors,whereas the maximum wave height at the far end was slightly higher than the initial wave as a result of wave reflection and superposition.Under the action of surge,the pontoon and river vessel exhibited the most significant roll response,with highly synchronized sway,surge and heave motions.The mooring ropes were subjected to tension close to the breaking load,posing risks of collision and instability.Preemptive untying of mooring ropes can substantially reduce the maximum roll amplitude of the vessel,enabling it to quickly restore stability via its own restoring moment and effectively mitigate disaster risks.

Abstract:College of Mechanics and Engineering Science,Hohai University,Nanjing 211100,China; 2.Institute of Science and Technology Research,China Three Gorges Corporation,Beijing 101199,China) Abstract：To address the issues of unclear local scour mechanisms and insufficient design basis for pile group foundations caused by complex flow field interference between piles,a three-dimensional coupled numerical model of fluid-pile-erodible seabed is established.This model simulates the scour process around a monopile and four typical pile group arrangements under steady current conditions on a sandy seabed with different pile spacings,and discusses the effects of flow field interference between piles and bed shear stress on the scour process.The study shows that in a twin-pile tandem configuration,the scour depth at the rear pile is reduced by 34%-53% compared with a monopile pile,owing to the shielding effect of the front pile.For side-by-side twin piles with G/D=2(where G is the pile spacing and D is the pile diameter),the maximum scour depth increases by 33% due to the gap flow between the piles.Compared with the monopile,the maximum scour depths for the regular-triangle and inverted-triangle arrangements increase by 20%-30% and over 30%,respectively.Therefore,it is recommended in engineering practice to adopt a pile spacing of G/D=3-4 for tandem piles to balance the shielding effect and scour risk,to employ a spacing significantly exceeding G/D=4 for side-by-side piles to markedly mitigate mutual interference,and to avoid using the inverted-triangle configuration as much as possible in three-pile arrangements.

Abstract:On the basis of the results of the tensile static load test of a large diameter steel pipe pile in Yantian Port and the finite element method,the tensile bearing characteristics of the steel pipe piles in the breccia geology are studied.The results show that by the finite element method,the axial tensile ultimate bearing capacity of SZ1# test pile is 2,297 kN,which has a surplus of 35% compared with the designed tensile bearing capacity of 1,700 kN.The friction coefficients between fully weathered breccia and strongly weathered breccia and steel pipe piles are 0.38 and 0.60,respectively.After the pile is loaded to failure,even if the pile top load increases,the axial force of the pile shaft in the soil section will not increase.At this time,the axial force curves of the pile shaft in the soil section overlap together under different loads.The tensile-lateral friction resistance of the steel pipe pile in fully weathered breccia and strong weathered breccia are 54.29 and 60.81 kPa,respectively.In fully weathered and strong weathered breccia,the relationship between the side friction resistance of the steel pipe piles and the relative pile-soil displacement of approximately follows a softening model and a hyperbolic model,respectively.While in medium-coarse sand and residual soil,it presents a bilinear hardening model.

Abstract:The construction of inland river wharf is faced with the problems of excavation stability of harbor basin bank slope and its influence on the surrounding environment.On the basis of an inland river frame wharf under construction in Zhaoqing,GEO5 software is used to calculate the excavation stability of wharf bank slope.Taking safety factor,internal force of pile body and displacement of pile top as control indexes,the reinforcement scheme of bank slope is compared and analyzed.Considering the construction period,the dense row piles are finally used for reinforcement.On the basis of the field monitoring results,the reinforcement effect is evaluated by comparing the allowable values of the code.The results show that the reinforcement scheme of slope bottom cement mixing pile and slope waist cast-in-place pile can meet the requirements of the code after appropriate optimization.Before and after the completion of bank slope excavation,the maximum surface displacement and deep horizontal cumulative displacement are about 7 mm,less than the early warning value of 20 mm,and the slope top building inclination rate and change speed do not exceed the early warning value.The reinforcement of dense row piles effectively reduces the influence of bank slope excavation on the overall stability and slope top structures,and ensures the safety of bank slope and surrounding environment.It can provide reference for similar projects in the selection and analysis methods of reinforcement schemes.

Abstract:Aiming at the problems of excessive settlement,insufficient stability,poor pertinence and low reinforcement efficiency of traditional foundation treatment methods induced by large-load stacking behind port shore connection structures under deep soft soil conditions,this paper presents a study on the design and application of zoned differentiated foundation treatment based on the Dapukou container terminal project in Jintang port area,Ningbo-Zhoushan Port.A combination of theoretical calculation,numerical simulation and on-site measurement is adopted for settlement prediction and stability analysis.The research results indicate that under the zoned differentiated design,the post-construction settlement is controlled within 30 cm,and the differential settlement between different blocks is less than 5 cm,which meets the service requirements of the yard.The measured data show that under the same load condition,the deviation in reinforcement effect between vacuum combined surcharge preloading and surcharge preloading does not exceed 10%.In addition,the zoned load reduction scheme increases the overall stability safety factors of the shore connection structure under construction conditions and seismic conditions by 26% and 23% respectively,both of which meet the requirements of the specification.This study verifies the feasibility and superiority of the zoned differentiated foundation treatment method,solves the deformation compatibility and stability issues associated with large-load surcharge preloading on deep soft soil foundations,and offers a replicable and scalable design scheme and technical reference for similar foundation treatment projects of shore connection structures in coastal deep soft soil regions of China.

Abstract:To the key technical issue of rapidly forming a containment structure for a super-large-scale offshore artificial island project under conditions of deep water,large waves,and hard soil foundation,a shallow-inserted steel cylindrical revetment structure is proposed.In-depth research is conducted on the structural stability,elevation rationality,and structural durability of this structure.The structural stability is comprehensively verified to meet the requirements by combining the normative formula,three-dimensional finite element numerical simulation,and centrifugal model tests.Through comparative analysis using the normative formula,physical model tests of wave section,and three-dimensional local and overall physical model tests,it has been verified that the installation of a twisted block wave dissipation platform can effectively reduce the top elevation of the revetment.The structural durability is demonstrated to meet the century-long usage requirements by adopting a combined anti-corrosion measure of anti-corrosion coating,sacrificial anode and external current cathodic protection,and concrete coating,in combination with corrosion allowance.The research conclusion indicates that the shallow-inserted steel cylindrical structure revetment is safe,reliable,and technically feasible,which can provide reference for the rapid island formation design of similar offshore artificial island projects.

Abstract:Addressing the challenges in the Yangtze River waterway regulation projects,where frequent monitoring of submerged dam cross-sections is required and structures are significantly influenced by the hydrological cycle of“deposition during rising water and scouring during falling water,”the conventional fixed-cross-section monitoring method often falls short due to its limited coverage.This limitation hinders accurate assessment of section compliance rates and comprehensive evaluation of scouring trends.To enhance the precision and scientific rigor of construction acceptance and flood season safety monitoring,a comparative and applied study of monitoring methods is conducted,focusing on both section acceptance and scouring assessment.Based on two typical regulation project cases,a comparative analysis is performed using the triangle network volume surface method alongside the traditional fixed-cross-section method.The results indicate that compared with the traditional method,the triangle network volume surface method analysis,by constructing a high-precision 3D digital model,achieves 100% comprehensive measurement of the dam and its surrounding riverbed morphology.This allows for more precise detection of localized non-compliant points,scouring pits,and siltation bodies that are missed between traditional fixed sections,along with their spatial distribution and volumetric changes.Consequently,this method provides powerful scientific data support for the detailed acceptance of construction quality,accurate prediction of scouring dynamics during flood seasons,and the formulation of protection and reinforcement plans,thereby effectively ensuring the long-term stability and safe operation of the regulation structures through flood periods.