Abstract:In the process of wave-structure interaction，if the incident wave direction and the structure are less than a certain angle，Stem waves propagating along the building will be generated.Its wave energy is rapidly concentrated during propagation，which has an important impact on the stability of the dike structure and the wave conditions in the harbor.In this paper，the variation law of Stem wave height distribution with wave incident angle under regular wave and irregular wave and the wave height distribution of Stem wave in front of different structural breakwaters are compared and analyzed through three-dimensional wave physical model experiments.The results show that the Stem wave height perpendicular to the axis of the vertical embankment is partial standing wave distribution under the action of regular wave and irregular wave，but the amplitude of the change of the Stem wave height perpendicular to the axis of the breakwater under the action of regular wave is significantly greater than that under the action of irregular wave.For non-perforated vertical embankments，under the same incident wave period，when the wave steepness is large，the comparative height of Stem wave is small.In the case of the different incident wave period，when the wave incidence angle is small for a non-perforated vertical embankment，the wave steepness has little effect on the comparative height of Stem wave.In the case of larger incident angles，when the wave steepness is large，the comparative height of Stem wave is small.The impact of wave incidence angle and whether the vertical embankment is perforated or not on the comparative height of the Stem wave in front of the vertical embankment is significant，and the law is obvious.

Abstract:Taking the storm surge by typhoon in the relevant sea area of Zhoushan as a research object，we analyze historical data from five tide gauge stations in Zhoushan，and obtain the process of storm surge and the variation rule of maximum storm surge caused by twelve typical typhoons including five types.The results show that the storm surge hydrographs of the same typhoon at different tide gauge stations are of the same pattern，though there are also exceptions.Among the five tide gauge stations，Changzhi Station observes the highest maximum storm surge caused by the same typhoon.The storm surge hydrographs of typhoons that landed in the Zhoushan-Hangzhou Bay area and moved northward along the East China Sea have similar characteristics，while those of different typhoons in the other three categories differ greatly.There is no strong correlation between the maximum storm surge and the astronomical tide and high tide level.The storm surge increases continuously as the typhoon (66.7%) approaches and quickly decreases after the typhoon makes landfall.The maximum storm surge value of each typhoon is not only related to the typhoon intensity and other characteristics，but also related to the geographical environment where the tide station is located.

Abstract:In view of the requirements of coordinating the relationship between water，road，port，shore，industry and city proposed in promoting the development of the Yangtze River Economic Belt，based on the analysis of the current facilities and transportation demand of the Yangtze River shipping，the relationship between the development of shipping itself and the coordinated development is grasped by using the method of system theory，and the three key factors affecting the development of shipping are found out，including industrialization，urbanization and transportation structure policy.Based on the future development trends of industries，cities，and transportation in the riverside areas，this paper proposes suggestions to promote the coordinated development of shipping，industry and city from four aspects：consolidating the basic position of the Yangtze River shipping，dealing well with the relationship between shipping and the adjustment of the development structure along the Yangtze River，strengthening the core support and leading role of the main line，and establishing sustainable linkage development models.The research has reference significance for promoting the development of the Yangtze River shipping.

Abstract:Aiming at the problems of fine particles，loose structure，large specific surface area and strong water holding capacity of extracellular polymer substances (EPS) on the surface and inside of dredged slurry，which makes it difficult to separate water from the dredged slurry，Fenton oxidation-compound coagulant method is used to carry out the rapid slurry and water separation test of dredged slurry.With the goal of maximizing the slurry volume reduction rate，the orthogonal test and response surface method are used to optimize the process conditions，and the change of EPS concentration is analyzed.The results show that the main factor affecting Fenton oxidation effect is chemical agent dosage.Under the same cost condition，the slurry and water separation effect after Fenton oxidation-polyaluminum chloride treatment is the best.The order of the factors influencing slurry and water separation effect determined by the response surface method is coagulant additives type＞stirring speed＞coagulant additives dosage.Under the conditions of this experiment，the optimal process conditions are that the polyacrylamide dosage is 0.255 g/L and the stirring speed is 125 r/min.After Fenton oxidation-composite coagulation，the content of positively charged protein in EPS increases significantly，which can neutralize the negative charge of slurry and realize the rapid slurry and water separation of dredged slurry.The research results have theoretical significance for the practice of rapid slurry and water separation engineering of dredged slurry.

Abstract:The high-quality development of the waterborne transportation industry requires that the use of port shoreline must be specialized，economical and intensive.However，there is no recognized calculation method or measurement for the intensive utilization degree of port shoreline，and it is difficult to quantitatively analyze the degree.Starting from the meaning of intensification，this paper puts forward the input index and output index to measure the shoreline，and gives the meaning and formula of the intensive utilization degree.Taking the shoreline utilization in two operation areas of a port in the middle and lower reaches of Xijiang River as an example，the indicators and the intensive utilization degree of shorelines are calculated，and the results are in good agreement with the actual situation.The measurement method for the intensive utilization degree of port shoreline can evaluate the current shoreline or be applied to the port shoreline planning，which provides guidance for shoreline planning and development，gives full play to the resource advantages of each shoreline，and maximizes its value.

Abstract:This article establishes a two-dimensional numerical model for the Wenzhou Nanguan Island Wharf Project，and analyzes and studies the tidal current field in the sea area near Nanguan Island before and after the project construction，as well as the distribution of erosion and sedimentation in the project area.The research results indicate that overall，the average flow velocity of the rising and falling tides in the waters near the project varies within 0.02 m/s，while the flow velocity and direction in other surrounding waters have not significantly changed.Due to the impact of local engineering，sedimentation has occurred in the surrounding sea area of the dock.The planned 100,000-ton dock front has a maximum sedimentation volume of 89,000 m3，the entry channel has a sedimentation volume of about 73,000 m3，and other water areas within the port have a sedimentation volume of about 58,000 m3.Under the condition of a 50 year return period of 12 hours of heavy wave action towards the ESE，the planned siltation amplitude in the port area is within 0.32 meters，and the total siltation amount in the port area is about 58,000 m3.

Abstract:Aiming at the problem of the strong impact effect of overtopping on the armour blocks of the breakwater's rear slope under long-period and rough waves，taking a Mediterranean petroleum and natural gas terminal expansion project as an example，we propose an optimized scheme of a cantilevered protective structure by widening the rear edge of the crown wall's bottom slab，carry out three-dimensional physical model tests and study of water conservancy industry standards，and analyze the stability results of this scheme.The results show that the cantilevered part，by widening the bottom slab of the crown wall，can shield the top of the rear slope armour blocks from the direct impact of overtopping.The armour blocks beyond the cantilevered part are located below the water surface.When the water depth is thick enough，it can reduce most of the energy of overtopping，thus satisfying the stability requirements of the armour blocks.Compared to increasing the elevation of the crown wall or enlarging the armour blocks of the rear slope，the cantilevered protection scheme has a low cost and good protective effect.

Abstract:Reasonable determination of the anchorage scale in port is beneficial to making full use of berth and channel resources and avoiding the waste of investment.At present，the study on the determination of the anchorage scale does not consider the influencing factors of multiple anchorages，complex channel networks，multiple wharfs and berths，and ship-to-shore handling equipment.Therefore，this paper proposes a method to determine the reasonable anchorage scale in port based on system simulation.By constructing a system simulation model，the paper simulates the actual operation process of the “anchorage-channel-berth” system，calculates the number of ships waiting to be berthed in the anchorage and waiting time，and determines the reasonable anchorage scale，which is applied to the determination of the anchorage scale in a Chinese port.The results show that the maximum number of ships waiting to be berthed in the anchorage or the number of ships waiting to be berthed in the anchorage with significant duration obtained from simulation statistics can be taken as the designed anchorage capacity.This method can provide support for the rational and scientific determination of the anchorage scale.

Abstract:The force analysis of the anchor chain system is a key point in the design of pontoon.According to the suspension chain theory，the calculation formulas for the anchor chain length and anchor chain tension are provided in Design Code for Wharf Structures.For the horizontal tensile force of the anchor chain in the formula，the code does not provide a corresponding calculation method.This paper analyzes the force state of the pontoon anchor chain system by setting different assumptions，proposes two simplified methods and the recommended methods based on static equilibrium analysis，and compares the calculation results of three methods through the case.The results show that the simplified calculation method considers the unidirectional force balance，which is only suitable for special conditions where the anchor chain angle is the same.The recommended method considers the force balance of the two directions of the plane，which is suitable for the general situation of different angles of the anchor chain.

Abstract:The magnitude of the wave height in the port has a significant impact on the mooring stability conditions.This article takes an offshore chemical terminal overseas as the engineering background and takes the new type of densely packed pipe piles breakwater as the research object to explore the transmission performance of the breakwater under different wave conditions.Based on the finite difference method of FLOW 3D，a three-dimensional numerical wave tank with a free water surface is established.The accuracy of the model is verified by comparing it with the experimental data.The results show that as the wave period increases，the transmission coefficient first increases and then tends to flatten.When the incident wave period exceeds a certain range，the protective effect of the breakwater on the waves is no longer enhanced.Under small-period wave conditions，the transmission coefficient increases with the increase in the width of the pile gap.When the relative width of the pile gap is 0.05，the transmission coefficient is less than 70%.The research results can guide practical engineering applications.

Abstract:The setting of liquid collecting tanks is an important factor to be considered in the design of liquefied natural gas (LNG) terminals and cryogenic liquefied hydrocarbon terminals.At present，there is no uniform regulation on the volume of liquid collecting tanks in the code，and the design standards are different，resulting in a large difference in the volume of liquid collecting tanks in terminals of the same type and grade.In view of this problem，combined with engineering examples，this paper discusses the leakage scene and leakage time according to the requirements of the current standard.By comparative analysis，the paper suggests that the complete rupture of the loading arm and the leakage of the pipe hole should be considered comprehensively in the selection of leakage scenarios.At the same time，the leakage time should be selected based on the operation time after system detection and isolation，so as to determine the scale of the liquid collecting tank that conforms to the engineering practice and is economically feasible.The research results can provide a reference for the design of similar liquid collecting tanks in terminals.

Abstract:This paper brings forth a new container yard handling process by integrating flyover technology into terminal scenario.It aims to provide a solution for isolation between automatic horizontal transportation equipment and manual horizontal transportation equipment without interfering terminal operation efficiency.By comparing with four typical handling processes，this paper reveals the characteristics of this new container yard handling process from both static and dynamic analysis including land utility，traffic organization，yard handling equipment sharability，dispatcher flexibility，system efficiency，investment cost，balancing the conflict between isolation proposal and operation efficiency improvement.With the continuous development of the terminal automation technology，it provides a new approach for the upgrading and transformation of new container automation terminals and traditional container terminal automation.

Abstract:Aiming at the low utilization rate of shore power equipment for ships waiting for lock in the Three Gorges Dam area，this paper analyzes the reasons to improve the existing shore power equipment.It designs a T-shaped interface box and an intelligent cable retracting and releasing system for pontoons，a shore power interface box suitable for ship berthing and mooring power supply，and a set of ship shore-based power supply system suitable for water level changes.This can solve the problems of difficulty in transporting power supply cables and obtaining electricity from shore for docked ships due to large water level changes.The implementation of the shore power system in the studied area mobilizes the ships enthusiasm to utilize shore power，significantly improves the efficiency of shore power equipment，and reduces air pollutant emissions.

Abstract:The confluence of the Maoping River as a tributary of the Pinglu Canal in natural conditions has a significant influence on the navigation conditions of the canal，and there are severe adverse hydraulic phenomena such as lateral flow and backflow in the confluence area，which affects navigation.Aiming at the navigation conditions of the confluence area of the Maoping River into the Pinglu Canal，this paper adopts three-dimensional numerical simulations to study the navigable flow conditions in this area under different flow combinations.Meanwhile，by combining the shortcomings of the design scheme in navigable conditions，it analyzes two aspects of incoming tributary water adjustment and confluence section widening.The results show that the optimized scheme yields sound results and improves navigable conditions of the canal，and the hydraulic indicators such as lateral flow velocity and return flow velocity can both meet the requirements of the relevant standards.

Abstract:In view of the problems of large weight and poor economy of ballast blocks in the sand-wave imitating soft mattress used in Jingjiang waterway regulation project，this paper develops a new type of ballast block on the basis of the ordinary ballast block.To analyze and compare hydrodynamic characteristics of the two kinds of ballast blocks，this paper uses a three-dimensional precise numerical simulation method to analyze the hydrodynamic characteristics of the two kinds of ballast blocks from three aspects of mainstream direction velocity，shear velocity，and turbulent kinetic energy，respectively.The paper concludes that the new ballast block still presents better hydrodynamic characteristics while saving 19.8% of concrete consumption.The research results can provide support for the ballast block design of the soft mattress.

Abstract:Sand pillow is a new material for throwing to protect banks，which has the advantages of stable structure and low construction cost.Previously used traditional throwing empirical formula requires the measurement of the water depth and velocity data before each throwing，with few models used to simulate the three-dimensional flow field，which consumes manpower and material resources.In order to improve construction efficiency，this paper uses the six-layer method and the eleven-layer method to predict the drift distance of the sand pillow respectively in combination with the Mike3 hydrodynamic model and the drift distance formula of the sand pillow by analyzing the vertical stratified flow velocity，and the paper finds that the eleven-layer method is more precise.

Abstract:If rock-throwing spur dike in the service process of the block is lost and the maintenance is not timely，it will lead to the loss of remediation function of spur dike.For the problem that it is difficult to observe the process of underwater block loss in real time，this paper presents the smart block monitoring method.The acceleration and flow velocity data of the block movement in different parts of the spur dike are measured using the flume generalization model test，the test data match the results of manual observation，indicating the reliability of the smart block monitoring method.The experimental results show that the block is subjected to turbulent flow，which generates nonlinear vibration processes.The probability distribution of the block vibration acceleration conforms to the normal distribution and inherits the randomness of turbulent fluctuations.The monitoring method proposed in this paper provides a basis for the selection of maintenance timing for rock-throwing spur dikes，and provides an important reference for the in-depth study of spur dike damage mechanism and sediment initiation.

Abstract:After the channel regulation from Shuanggang to Chuxi estuary of Raohe River，there are some shallow sections obstructing navigation in extremely low water conditions in 2022.Based on the measured data and mathematical model calculation，this paper calculates and analyzes shoal evolution，designed water level changes of the basic station，and the lowest navigable water level.The results show that the navigation channel from Zhupaoshan to Chuxi estuary is mainly cut down，with an average value of 0.7-3.0 m and a total scouring volume of 1.373×106 m3.Meanwhile，the hydrological series are extended to 2021，and the designed water level drop of the basic station will be 0.12-0.61 m.Under the designed lowest navigable flow，the maximum water level decline in lake reach of Raohe channel is 0.13-0.25 m，with an average of 0.05-0.11 m.

Abstract:Based on Manbing beach risk regulation in Lancang River，this paper analyzes the causes of navigation obstruction from the canyon beach risk gradient，flow velocity，flow pattern，and beach risk abatement indicators to deal with water level fall decline in beach risks and upper beach risks caused by canyon-type beach risk regulation.The basic channel dimensions should be protected by reef blasting，and the regulation structure should be abandoned to mitigate the water level fall of beach risk regulation and adjacent upstream beaches.The results show that in the regulation of broad-shallow and narrow-deep，shallow areas and deep pools，the cross-section structure of narrow deep reef blasting and body structure of broad-top adverse slope submerged dam can reduce the water level fall under the premise of meeting the basic channel dimensions of the beach.This provides certain references for future regulation of similar beach risks.

Abstract:For large bending moments in the monolithic lock chamber floor，this paper studies the influence of setting a relieving slab on the lock wall on the internal force of the lock floor.The paper adopts three-dimensional nonlinear finite element analysis and draws the following conclusions：1) Setting a relieving slab on the lock wall will reduce the compressive stress on the upper surface and tensile stress on the lower surface of the side pier floor.In addition，it will increase the tensile stress on the upper surface at the mid-span and the settlement at the side pier floor.2) Compared to the relative height，the cantilever length of the relieving slab will have a greater influence on the lock floor bending moments.3) During engineering design，the relieving slab is set at a height of 1/3-1/2 of the lock chamber wall and below the water level of the drainage pipe.In this condition，the stress condition of the lock floor is good with the cantilever length of the relieving slab set at 0.10-0.15 times the lock chamber wall height.The lock chamber floor designed with the relieving slab has better stress conditions，providing references for the height to width ratio and foundation soil quality of similar projects.

Abstract:The Gezhouba ship lock has been suspended for repairs due to multiple damages to the bottom water seal device of the miter gate，resulting in a long suspension time and causing huge losses to the Yangtze River shipping.The reason for the damage to the bottom water seal is analyzed.It is proposed to change the active segment of the sealing device into a fixed segment.The gap between the bottom water seal and the threshold is increased when the miter gate is fully closed.The sealing bolts of the bottom pivot segment are changed from counterbore bolts to through-hole bolts.The strength of all sealing fixing bolts is increased.Two anti-loosening nuts are installed to improve the sealing device's working conditions and reliability.The gap value between the bottom water seal and the threshold is obtain by calculating when the miter gate is fully closed.It is ensured that the bottom water seal is just in contact with the threshold when the miter gate is closed.The results show that the water seal devices of miter gates for the three Gezhouba ship locks are reconstructed，which have good operation effect.

Abstract:The original steel sheet pile longitudinal cofferdam downstream of Gezhouba is a temporary facility and has now exceeded its service period.This paper studies the impact of steel sheet pile cofferdam on the navigation safety of the ship lock No.1，providing a basis for the demolition or reconstruction of steel sheet pile cofferdam.A two-dimensional hydrodynamic model is established for the downstream channel of Gezhouba Dam，and numerical simulation calculations are conducted for the demolition and reconstruction of steel sheet pile cofferdams under the maximum navigable flow of 35，000 m3/s at the Ship lock No.1.The calculation results show that when the diversion ratio of the two rivers is less than 0.9 and the smaller，the demolition of the steel sheet pile cofferdam has a greater impact on the navigation flow conditions in the downstream entrance area of the ship lock No.1.

Abstract:Maintaining and dredging the shallow reefs and shoals in the Lanjiatuo Waterway are difficult due to the complex navigation environment.This paper proposes a reasonable dredging scheme after analyzing the difficulties in implementing maintenance in the research section.According to the process of changes in water levels in the Huangniwan gauge in recent years，this paper advocates advancing the dredging construction time from the dry season to the middle water period.The paper also optimizes the layout of the channel during the construction period，the mud throwing position，and the construction sequence，so as to achieve non-prohibited navigation during construction.Based on the implementation effect of the scheme，the construction quality meets the design requirements，and the construction period is shortened from the expected 30 days to 23 days.While ensuring the normal economic benefits of the waterway，the dredging scheme also reduces the construction costs.

Abstract:Navigation is one of the functions of Xiangjiaba Hydropower Station.To give full play to the navigation benefits of the power station and clarify the suitable navigation flow conditions for the power station，the maximum navigation flow of the power station was preliminarily determined to be not more than 8 500 m3/s and the maximum flood discharge is not more than 2 200 m3/s dual-control standard through the full-scale ship trial navigation tests in the early stage.However，in recent years，it has been found that the navigation flow conditions of Xiangjiaba Hydropower Station are not only affected by the discharge flow，but also affected by the flood jacking effect of the downstream Minjiang and Hengjiang rivers.By establishing a one-dimensional unsteady flow model from Xiangjiaba to Luzhou，this paper simulates the daily and hourly variation of water level at Xiangjiaba Hydropower Station after encountering different typical annual frequency floods of Minjiang River and Hengjiang River with 5-100 years return periods during the flood season，when the flow rate of Xiangjiaba Hydropower Station is constant at various levels from 4 000 m3/s to 8 000 m3/s，respectively.It is calculated that when encountering the 50-year flood of Minjiang River and the 100-year flood of Hengjiang River，the hourly variation amplitude of the maximum water level at Xiangjiaba Hydrological Station is 0.55 m/h and 1.19 m/h respectively，and the daily variation amplitude of the maximum water level is 7.59 m/d and 6.87 m/d respectively.In addition，only when encountering the flood jacking of Minjiang River and Hengjiang River with a return period of 5-10 years，the water level of Xiangjiaba Hydrological Station meets the dual control requirements of no more than 1 m/h and no more than 3 m/d，and the water level variation under other conditions exceeds the standard.The research results can provide a reference for the navigation dispatching of Xiangjiaba Hydropower Station in the future.

Abstract:Qixingdun ship lock is an important node project of Wujiang Channel of Beijiang upward extension project.Its effective scale is 190 m×23 m×4.5 m (length×wide×water depth of threshold)，and its designed water head is 7.5 m.Combined with the general layout of the junction，according to the requirements of the code，the ship lock adopts the distributed water conveyance system with the side branch holes of the lock wall gallery.The model test of the water conveyance system shows that the water conveyance system of the ship lock in the original design scheme has some adverse hydraulic phenomena，such as the low pressure of the gallery behind the sluice valve，the continuous air-breathing vortex at the inlet，and the local high phenomenon near the outlet.Based on the comprehensive study of the layout of the whole ship lock and the water conveyance system，and combined with the hydraulic characteristics of the test，this paper proposes optimization measures such as lowering the sluice valve section of the ship lock，optimizing the layout of the inlet grid，and adjusting the baffle sill at the outlet.All the hydraulic characteristics of the optimized water conveyance system of the ship lock have reached the expected goals and requirements.

Abstract:As an ecological and environmentally friendly method for reef cleaning，the rock breaking method by a breaking hammer is increasingly widely used in engineering construction and waterway regulation and excavation.However，there are few studies on the evolution rule of reef damage under high-frequency vibration impact，and insufficient studies are conducted on the impact parameters of a breaking hammer on reef damage.Based on the field test data of underwater reef cleaning by a breaking hammer，this paper establishes a numerical calculation model for rock damage under the impact of a breaking hammer，explores the rules of reef breaking by a breaking hammer under different parameters，and analyzes the main controlling factors of reef breaking by a breaking hammer by using the range analysis method.The results show that with the increase in operating oil pressure，the reef breaking parameters increase nonlinearly，and the reef breaking volume increases linearly.With the increase in impact frequency，the value of the reef breaking parameters first increases and then remains unchanged.With the increase in reef strength，the value of the reef breaking parameters decreases.The operating oil pressure is the main controlling factor for the efficiency of reef breaking by a breaking hammer，followed by the impact frequency，and finally the reef strength.

Abstract:The calculation formula for the number of mud barges in Construction Code for Dredging and Reclamation Works has limitations.Different mud barges with different performance parameters and loading sequences in dredging engineering have different impacts on the time availability of the main ship and the waiting time of the mud barges.We introduce the concepts of the operation network circuit diagram and bar chart of the mud barge system，and establish a mathematical model for the operation of the mud barge system on this basis.We introduce the evaluation indicators of the accumulated dead time of the main ship and the accumulated dead time of the mud barge，propose an optimization method for the mud barge configuration and loading plan of the main ship with one or two sides berthing，and verify the model and optimization method through examples.The results show that the optimization of the mud barge loading sequence is achieved for the established mud barge fleet.For the proposed mud barge system，the optimal configuration plan and initial loading sequence optimization of the mud barge are achieved.

Abstract:In view of the problems of low efficiency and difficult deformation control in the construction of large-area sand filling near the existing bridge structure，combined with the east artificial island project of Shenzhen-Zhongshan Link，this paper determines the sequence and method of filling under the bridge based on numerical simulation，explains the key construction techniques of backfilling island construction，and verifies the construction effect by monitoring data and arch silt sweeping.The results show that the backfilling principle of “pile-sand quilt-cross-bridge left/right alternating”，combined with sand splitter and other devices can control the deformation of the existing bridge within ±5 mm and reduce 66.7% of arch siltation.The deformation correction effect of pile back pressure and unloading in the opposite direction is significant.The backfill sand volume needs to focus on the backfill density，mud content，and the loss of the filter layer of the island wall.The backfill sand loss rate in the test section of this project is 4.21%.

Abstract:Based on the working conditions of a cutter suction dredging robot，this paper uses Fluent software to create a cutter suction model，so as to numerically simulate the over and under cutting processes of the cutter under different cutter suction parameters.The paper analyzes the sediment concentration distribution at the entrance of the duckbill tube and the key section of the cutter and studies the flow field characteristics of the cutter during the over and under cutting processes，providing a theoretical basis for the reasonable selection of cutting speed of the cutter for the underwater dredging robot.The findings suggest that during the cutter suction process of the dredging robot，the phenomenon of sediment backfilling is more pronounced during over cutting，while the phenomenon of sediment squeezing is more pronounced during under cutting.It is not advisable to operate the cutter at a high speed during the cutting process，as high-speed cutting can cause unstable sediment concentration during pumping.For low-level pumping flow rates，the cutter speed should be controlled at 15-25 r/min，while for high-level pumping flow rates，the cutter should be controlled at 25-35 r/min to improve productivity.Furthermore，the paper recommends not to arrange the duckbill tube symmetrically but to install it at a certain angle along the rotation direction of the cutter，so as to improve the efficiency of sediment suction.

Abstract:：Regarding the design and construction of the above-water and under-water structures of the concrete cofferdam，taking the longitudinal concrete cofferdam of the Yanzhou project phase I as an example，through the comparison and analysis of the structure design of the above-water part and the construction technology of the underwater part of the cofferdam，the gravity design scheme of the above-water part and the prefabricated casing technology of the underwater part are optimized.The results of theoretical calculation and field practice show that the gravity scheme has more advantages in reliability，structural stability and ease of construction.Compared with the traditional steel box technology，the prefabricated box technology can shorten the construction period by 22 days，avoid the steel box turnover，and save 1.83 million yuan construction cost.The research results can be used for reference in the design and construction of cofferdams of the same type of hydraulic engineering.

Abstract:In recent years，the development of cutter suction dredger gradually develops to environmental protection and green energy saving，and the anti-diffusion technology is the core of the development of environmental protection cutter suction dredger.In this paper，the prototype environmental protection reamer is further reformed by adding movable flaps on both sides of the reamer cover to flexibly adjust the cutting depth and suction concentration of the reamer.The CFD (Computational Fluid Dynamics) software is used to simulate the prototype reamer and the new reamer，and the flow field on both sides of the reamer is compared in the cutting process.The results show that the diffusion prevention effect of the new reamer is obviously better than that of the original reamer.From the perspective of structure，the cutting depth of the new reamer is flexible and adjustable，which can meet the requirements of different field conditions，and provide a certain theoretical basis for the subsequent construction of economic and environmental protection cutter suction dredger.

Abstract:The stone column method is a widely used anti-liquefaction foundation treatment technology.Currently，existing Chinese specifications mainly consider the effect of stone columns on the densification of soil between columns in the design and testing and acceptance phases of the stone column，while ignoring the drainage effect and shear stress redistribution effects on anti-liquefaction.In the strong earthquake area，the requirement for an anti-liquefaction foundation is high.If the stone column treatment only considers the effect of densification of soil between columns，it will lead to a high replacement rate of stone columns and cause engineering waste.In view of the lack of testing and evaluation methods for the comprehensive anti-liquefaction effect of stone column composite foundation in China and abroad，this paper refines the core elements of the evaluation for the anti-liquefaction effect of stone column composite foundation and proposes the evaluation methods for each of the three major anti-liquefaction effects based on the calculation formulae for the three major anti-liquefaction effects of stone column composite foundation，namely densification，drainage，and shear stress redistribution.Combining with engineering examples，the paper also puts forward the process of testing and acceptance of the anti-liquefaction effect of stone column composite foundation in strong earthquake areas and the comprehensive evaluation method，which can provide a reference for the testing and evaluation of the anti-liquefaction effect of similar foundation reinforced by stone columns.

Abstract:Quality control of gravel leveling is an important prerequisite for successful installation of the immersed tube tunnel during construction.Taking the immersed tube tunnel foundation gravel leveling project of the Shenzhen-Zhongshan Link as an example，aiming at the high-precision construction requirement of ±4 cm proposed for this project，we put forward a series of optimization adjustments to the multibeam measurement method based on the construction site，propose a direct depth calibration method to improve precision，and compare and verify the multibeam data by multiple methods，such as point method and line method etc.The results show that this multibeam sounding technology can meet the engineering requirements.The application of the multibeam sounding technology can meet the result detection of multiple stages of construction，such as gravel leveling and backfilling of tube.