Abstract:To evaluate the development of China's cruise economy scientifically，and promote the development of cruise industry in coastal cities of the 14th Five-Year Plan and beyond，a “two-stage and multi-dimensional” cruise industry selection and evaluation system is constructed considering the coupling effect of cruise industry and cruise market based on the settings such as statistical classification of cruise industry，different mechanisms of territorial industries and related industries，and selection and evaluation criteria.The results of research are applied in Hainan，different development position of the nine main-category industries and development emphasis of each medium-category industry are clear combined with the characteristics of Hainan's economy and the requirements of Hainan Free Trade Port construction.The research will support the construction of Hainan International Tourism Consumption Center and Free Trade Port.

Abstract:To reasonably assess the current development situation and spatial distribution characteristics of China's port industry and clarify the advantages and disadvantages，this paper takes 61 coastal cities in 11 provinces as research objects，calculates the output value of China's port industry in each coastal city based on the input-output basic flow table and related methods，and analyzes the current situation from the perspective of total volume，industry and city contribution，and further adopts the kernal density estimation method to specify the spatial distribution characteristics of China's port city and port city industry.The results show that the port industry is more developed in China's coastal cities，and the output value of port industry in more than 30% of the cities is close to or beyond 100 billion yuan，among which the Yangtze River Delta and the Pearl River Delta are the most densely clustered.61 coastal cities can be divided into 4 levels.

Abstract:On the basis of analyzing the economic and trade growth changes of the main hinterland ports in the Pearl River Delta，as well as the production changes of key industrial products，this paper systematically reviews the port's cargo throughput，key cargo category throughput，and structural change characteristics.Based on the judgment of the future trend of economic，trade，and industrial structure changes in the Pearl River Delta region，and in response to the characteristics and adaptability of different types of goods，this paper comprehensively selects multiple prediction methods such as linear regression，non-linear regression，curve fitting，freight intensity，and elasticity coefficient to analyze and predict the cargo throughput and classification throughput of coastal ports in the Pearl River Delta.It is expected that in the future，the cargo throughput of the Pearl River Delta ports will continue to grow.The scale of cargo throughput in 2025 will be around 1.70 billion tons，and the average annual growth rate from 2022 to 2025 will be around 4%.Among them，the container throughput will reach 70 million TEUs，and the average annual growth rate from 2022 to 2025 will be around 3.2%.

Abstract:The existing structural monitoring methods are still unable to monitor the irregular berthing of wharf in real time.This paper proposed an inversion model based on support vector machine for real-time monitoring of ship impact force in overhead vertical wharf.Combined with the structural characteristics of overhead vertical wharf，the importance of wharf pile foundation is evaluated based on generalized structural stiffness，and the monitoring pile foundation is optimized.In this paper，the 10th structural section of Xintian Port Wharf Phase I in Chongqing is taken as the generalized research object，and the physical model of the wharf is constructed according to the scale of 1:20 to simulate the irregular berthing effect.The collected strain data of optimized pile foundation are trained and verified by inversion model.The accuracy of the inversion model for the position of impact force is 0.98，and the average relative error for predicting the strength of impact force is 0.234%.

Abstract:The single point mooring system of oil tankers adopts solitary point arrangement，so there are no land facilities to rely on.In case of an accident，only motor ships are used for emergency protection.Therefore，the configuration for fire-fighting and oil spill emergency facilities of the most credible accident is crucial.According to the Code for Fire Protection Design of Oil and Gas Chemical Terminals，combined with the characteristics of single point mooring，this paper introduces the concepts of pool fire and safety protection distance.It also put forward the allocation requirements for fire boats.For the characteristics of no fixed oil boom during loading and unloading operation，it is proposed that self-configured oil spill emergency facilities should meet the requirements of Class I protection capacity.The calculation method and minimum configuration requirements of oil spill emergency facilities are provided by comparing the Guidelines on the assessment of ship-source oil's response capability and the Requirements of safety operations for oil tankers at single point mooring.

Abstract:Based on the design codes at home and abroad and some international project cases，this paper introduces and discusses the standard of allowable overtopping limits，the stability standard of armour stone and the seismic slope stability standard under different return periods adopted in the design of breakwater and revetment structures.Considering the return period of design conditions combining with the features of project protection function，the design concept of multilevel checking standard based on performance is worth popularizing for the international projects.In contrast，the traditional Chinese fortification standards mainly focus on the effect design values，and the provisions of resistance design values，structural required limits and other checking standard are relatively simple.It is suggested that the multilevel checking standard appropriate for the Chinese national conditions and structural characteristics of the project can be given in the code.

Abstract:For the limitations of the wave dissipation performance of traditional permeable breakwaters，we innovatively propose a pile foundation breakwater with low permeability based on closely spaced battered piles.It realizes full shielding of the wave face by setting rib plates on the pile side and crossing the front and rear axes of the pile positions.We analyze the stress characteristics of a closely spaced battered pile structure base on a land-island traffic wharf project.Then we study the design details of closely spaced battered pile，rib plate，lifting lug and superstructure connection and put forward corresponding solutions.The results show that the transmission coefficient of this type of breakwater can be reduced to below 0.2，and it is suitable for waves of higher heights and longer periods.

Abstract:Regarding the problem of setting seawall entrance during the construction of the seawall in nearshore tidal flat areas，a mathematical model of the nearshore tidal flat area is built as a research tool to simulate the hydrodynamic conditions of the tidal flat area where the seawall is located and the exchange between the water enclosed by the seawall and the open sea.We study the relationship of the size of the seawall entrance with the flow velocity at the entrance，the exchange time，and the exchange rate of water enclosed by the seawall.The calculation results show that the nearshore tidal flat areas are affected by the terrain elevation，and most tidal flat areas are exposed during the ebb phase.For the seawall built in this area，when the size of the entrance is more than 100 m，it can not only ensure that the maximum flow velocity at the entrance can be controlled below 1 m·s but also realize that all water inside the seawall can be discharged to the open sea in a tide cycle，achieving an exchange rate of 100% with the open sea water，which provides a decision-making basis for the later setting of seawall entrance.

Abstract:The non-axismetrical caisson may be eccentric in long distance floating transport.Based on hydrostatic pressure distribution of eccentric caisson，the calculation method of initial inclination angle is deduced by using the water pressure moment balance method，and the ratio of draft to width and eccentric distance to width are taken as variables to evaluate the effect of boundary dimension and distribution of mass on initial inclination angle.Finally，according to the geometric relationship between gravity and buoyancy of caisson，metacentric radius of eccentric caisson is calculated，and the influence law of initial inclination angle and ratio of width to draft on metacentric radius is summarized.This study provides a method for calculating the floating stability of caisson floating，which can provide a basis for evaluating the safety reserve of long distance floating transport.

Abstract:At present，there are four lanes of locks in Changzhou multi-purpose dam.The down bound cargo volume in 2021 reached 119 million tons and was close to the capacity of locks.In the study of scheme for a new lock，the capacity of existing locks and the new lock should be analyzed in accordance with the cargo volume forecast.The formation of vessels through the lock and the average dead weight tonnage and loading rate of each class of vessels are predicted.Based on discrete event system simulation，a model of lock group is built，simulating the random arrival of vessels and ship arrangement algorithm in lock chamber，and considering different ship distribution rules among multi-lane locks.The results show that the total capacity of lock group is relatively optimal if ship enters lock by its arriving order.Besides，the fifth lock should be built at a new location and plane dimension of 340 m ×34 m is suitable for it.

Abstract:Deposition at cross estuary affects the normal navigation of ships and leads to grounding accidents.In order to make full use of the navigation function of the waterway，it is necessary to analyze the causes of navigation obstruction in time and formulate waterway dredging plans to ensure smooth and safe navigation of the waterway.This study takes the cross estuary of Tongyang Canal and Taidong River as the research area，and establishes a two-dimensional Delft 3D water-sediment model to analyze its sediment movement law and geomorphic evolution characteristics in combination with the actual measurement.Based on different dredging elevation and dredging slope，six channel scale schemes are designed，and through simulation analysis，an optimization scheme that takes into account the navigation safety of passing ships and the economic cost of dredging is obtained.This study can provide reference for the channel scale design and optimization of similar crossing estuaries.

Abstract:Channel excavation along the canal project will produce large areas of artificial wounds，and the ecological bank slope protection works have a positive effect on wound repair.In this paper，the bank slope protection of Anhui section of the Yangtze-to-Huaihe water diversion project is taken as the research object to comb the use of the ecological bank slope protection structure of Anhui section of this project based on the design data and field survey.The results show that the type selection of the ecological structure of this project is mainly affected by the geological conditions and the characteristic water level.The concrete prefabricated block structure with a porosity of about 30% is mainly used above the normal water level of the soil bank slope，and the underwater matrix block structure with fish spawning nest function is used experimentally in local river sections at low water level.The large-frame prefabricated block structure and flexible water-level retaining blanket material are used in the expansive soil area，with porosity of 79% and 95% respectively，and the using area is above the highest flood level.

Abstract:The piers and navigable holes of bridges arranged in navigable waters limit the navigation of ships，and thus the demarcation of bridge area scope is of great significance to guide the safe navigation of ships.We analyze the influencing factors for the bridge area scope delimitation by sorting out the navigation restrictions in the current bridge area laws and regulations.According to the influence of the bridge piers on the navigating ships in the waterway，we design the methods for calculating the width and length of the bridge area scope based on the ship domain theory，which can demarcate the bridge water area scope according to the bridge and waterway characteristics，and realize the one bridge one policy.The method is used to demarcate the bridge area scope in the Yangtze River.The results show that compared with the traditional method of bridge area scope demarcation，the method proposed in this paper can not only ensure the safety of ships sailing in the bridge area but also reduce the navigation constraints of the ships near the bridge while avoiding the waste of shoreline resources.

Abstract:Aiming at the increasing navigation demand of the Xiangjiaba Hydro-project，to ensure the normal operation of the Xiangjiaba Hydro-project，we carry out continuous water and sediment monitoring in the navigable waters near Xiangjiaba from 2019 to 2021.Based on the 3-year measured topographic data and the characteristics of water and sediment in the Xiangjiaba reservoir area，we analyze the erosion and deposition changes in the navigable waters near Xiangjiaba.The results show that the Fanba wharf at the upstream of the dam is silted up，whereas the amount of siltation is not large.The Liangshuijing wharf is eroded year by year，and the erosion area is mainly located in the deep groove.The erosion in the downstream waterway of the dam is obvious.The monitoring and analysis of the port wharf and the navigable waters below the dam should be continuously strengthened to ensure the stability of wading structures and the navigation safety of vessels.

Abstract:The flexible mattress is the main beach protection structure in the middle and lower reaches of the Yangtze River，the strain response characteristics of its deformation are important for evaluating and analyzing the service state of the flexible mattress，there are few studies on this.To address the current difficulties in the study of the strain response characteristics to the subsidence deformation of flexible mattress，we carry out the model experiments，and study the strain response characteristics under the subsidence deformation of flexible mattress to propose the identification method of subsidence deformation.The results show that the section strain response to the subsidence deformation of the flexible mattress can be characterized as “bimodal” distribution.This distribution feature is formed by the internal mattress bending and coiling inward，driving the fiber under pressure through the fixation at the fixed point，resulting in a negative strain in that part of the sensing fiber.

Abstract:Submerged closure dams are often used in channel regulation projects to adjust the diversion ratio of branches，and the structure is generally composed of the dam body and the bottom protection mattress.Since the submerged closure dam crosses the branch of deep water with high flow velocity，it has an obvious regulating effect on water flow and can easily cause local violent scouring of the riverbed，and the changes in the riverbed react on the building structure，thus leading to local deformation and even damage.This paper selects two submerged closure dams in the left branch of Hechangzhou Waterway as a typical case and analyzes the effects of building implementation，as well as the deformation and local damage of the building by using measured data combined with water flow simulation analysis.Then，the paper discusses the characteristics and causes of local damage.The results show that the dam body is basically intact，and the deformation mainly occurs at the edge of the bottom protection mattress；the damaged area of the mattress corresponds to the location where the intense scouring occurs near the buildings.The main causes of damage are the mainstream scouring of the deep channel in the waterway during the flooding period，the turbulent scouring of the downstream water flow in the slope change area of the dam body，and the accelerated damage of the mattress during the long period of flooding in special hydrological years.

Abstract:Waterway is an important infrastructure supporting coastal ports to play the role of hub portals and also an important object for government departments to provide overall support in planning，construction，maintenance，and other aspects.As China's national economy and foreign trade rapidly develop and the large-scale ships continue to evolve，the waterway construction in China's coastal ports has gradually increased in scale，and the term “coastal waterway” has been widely used.However，the specific definition and the criteria for delimiting the spatial category are not clear，which also brings some problems in industrial management.In this paper，we summarize the normative definitions of coastal waterways in detail and analyze the development process of coastal waterways.Based on laws and regulations，the actual management situation of each region，and other factors，we put forward suggestions on the definition and planning formulation of “coastal waterway”.The suggestions provide a technical reference for deepening understanding and grasping the spatial category of “coastal waterway”，scientifically formulating coastal waterway planning schemes，and supporting government departments in reasonable decision-making and scientific management.

Abstract:According to the general schedule，Goupitan Hydropower Station is planned to impound after the flood season in 2008.The first stage ship lift located in the reservoir needs to complete the underwater construction before impounding.The layout and selection of the first stage ship lift are extremely difficult due to the constraints of topographical and geological conditions，layout of the left bank cable crane platform，construction schedule requirements and other factors.Based on the researches on the selection and layout scheme of the first stage ship lift model of the navigation building of Goupitan Hydropower Station，this paper comprehensively compares the conventional full balance ship lift model with the launching vertical ship lift model from the aspects of technical conditions，throughput，construction period，economic benefits，etc.An innovative layout scheme of the upstream launching vertical ship lift is proposed to solve the core contradiction that the construction of ship lift restricts the water storage and power generation of the project.

Abstract:In view of the navigation obstruction problem of Qichun waterway in the middle reaches of the Yangtze River，this paper studies the regulation project scheme，determines the regulation objectives and principles，and proposes the idea of structural design.In addition，the paper optimizes the bottom protection structure，the structure type of the high beach protection project，the bank protection reinforcement structure，and the underwater addition of fish nest bricks.It also analyzes the waterway project regulation effect through a movable bed test of the physical model and verifies the regulation effect through effect observation after the project is implemented.The regulation project has achieved the construction goals.

Abstract:After the operation of Three Gorges Reservoir，there has been a problem of sediment siltation in Shangluoqi reach in the fluctuating backwater area of Three Gorges Reservoir，which has a certain impact on the channel conditions.Based on the measured data，this paper analyzes the movement law of the pebble sand wave group in Shangluoqi reach.It is found that the length of the pebble sand wave in Shangluoqi reach is 40-60 m，and the wave height changes about 0.8-1.6 m.According to the physical model experiment，the channel regulation scheme is proposed.The regulation results show that this scheme can effectively improve the navigation conditions of Shangluoqi reach，and the channel regulation effect is excellent.

Abstract:To ascertain the cause of the wear of the PTFE anti-friction layer on the chamber gate of the Three Gorges ship lift，a nonlinear finite element calculation model of the water seal of the chamber gate is established according to the actual operating conditions of the chamber gate.By simulating the water retaining and operating conditions of the chamber gate，the effects of different rubber materials and pre-compression on the maximum contact stress，positive pressure and maximum offset of the ship chamber gate water seal are calculated.The results show that the contact stress，normal stress and maximum offset of the chamber gate decrease with the decrease of the hardness of the rubber material.The lower the water head is，the higher the sensitivity of the material hardness is.The contact stress and normal pressure increase with the increase of the pre-compression.Especially in the pre-compression stage，the normal pressure of the water seal increases significantly with the increase of the pre-compression.Finally，it is proposed to slow down the wear of the water seal PTFE anti-friction layer on the chamber gate by optimizing the water seal rubber material and reducing the pre-compression.

Abstract:Taking Baihetan Reservoir area of Jinsha River as an example，for the fluctuating backwater section of Laojuntan，the river bed gradient is large，and the regulation measures can not be adopted to meet the requirements of the planned waterway grade.The traditional combination scheme of guaranteed discharge and water level in front of dam does not accord with the actual shipping requirements and navigation conditions.The method of simulating the operation of Xiluodu is discussed，and the design minimum navigable water level is determined comprehensively considering the influence of backwater of Baihetan and the regulation measures.At the same time，the natural condition and the navigation guarantee rate after the regulation measures are calculated in sections for the navigation channel regulation decision.

Abstract:This paper summarizes the maintenance practice of miter gate bottom pivots since the planned overhaul system was implemented in Gezhouba ship lock in 1990.The maintenance cycles of upper and lower miter gate bottom pivots are 18-24 a and 12 a respectively，which can satisfy the normal operation of the bottom pivots.Whether the contact surface of the bearing bush and the mushroom head meets the requirements is an important factor to ensure the safe and reliable operation of the bottom pivots.The bottom pivots of the downstream and upstream miter gates are repaired with the gate body detached or not respectively.The bearing bush and mushroom head of the bottom pivot are processed and repaired by the vertical displacement of the ball center.The diameter of the bearing bush is equal to the size of the mushroom head.The mushroom head does not feature a surfacing layer type.The replacement process is implemented by using carbon arc gouging to disconnect the old bearing bush and install a frozen new bearing bush.The above maintenance process saves costs and shortens the construction period.Adding limited displacement devices can prevent permanent displacement of the bottom pivots due to the ingress of sediment.

Abstract:In view of the landform and geological conditions of Lijiazhou beach，according to the flat terrain and slow flow velocity of the beach surface，the surface layer is soft plastic，local flow plastic muddy silty clay，which has high water content，high void ratio，low permeability，high sensitivity，low strength，high compressibility，rheology and other engineering properties.For onshore beach surface protection，3D stiffened mesh cushion with good permeability，which can promote sediment deposition，facilitate vegetation growth，improve the ecological environment of beach surface，and have good environmental protection，shall be selected.It greatly reduces the earthwork excavation on the beach surface，which is conducive to water and soil conservation，has little impact on the natural ecology and water flow environment，has the ecological restoration function，and the overall ecological effect is good.The current pattern of shoal and channel has been stabilized to prevent the channel conditions from developing in an unfavorable direction.

Abstract:Laomukong navigation-power junction ranks the first among the four recently developed navigation-power junctions in the 162 km reach from Leshan to Yibin in the downstream Minjiang River.The navigation conditions during the construction period will directly affect the transportation of large ships in the reach.To ensure smooth shipping in Minjiang River during the construction period，the temporary open channel expanded at the left bank is available for navigation during construction period I.This paper adopts the method of combining hydraulic physical model tests with ship model tests to systematically study the navigation schemes and flow conditions in the dam area during the navigation period of the left branch of Sanjiang Village in the first dry season during construction period I.The paper also proposes the recommended schemes of expanding the open channel in the left bank for dredging，designing the inlet reach of the open channel，and arranging the downstream outlet of the open channel and connecting reach，as well as corresponding characteristic parameters of the navigation flow conditions.The results show that the recommended schemes for the dam area of Laomukong junction during the construction period ensure excellent navigation flow conditions，and the minimum and maximum navigation flows meet the navigation requirements during the construction period.

Abstract:We analyze the changes in water and sediment conditions in the upper reaches of the Yangtze River in recent years based on the measured data.It is concluded that the flood season drought of 2022 can have adverse effects on waterway maintenance.By summarizing the practice of waterway maintenance and dredging in recent years，we point out that waterway maintenance in the upper reaches of the Yangtze River mainly has the following problems.The adverse evolution trend of key shoals is getting worse；the number of shoals obstructing navigation is increasing；the time of obstructing navigation and the timing for maintenance and dredging are highly concentrated；the organization for maintenance and dredging is difficult.To deal with the problem of concentrated shallowing in multiple channels under possible adverse hydrological conditions，we propose to strengthen the medium and long-term water regime forecasting，carry out the accurate design of key shoals，and adopt a comprehensive maintenance mode that combines waterway maintenance and dredging with the maintenance of waterway regulation structures，which can provide a reference for future waterway maintenance and regulation.

Abstract:The periodic dry and wet changes of the fluctuation zone in the Three Gorges Reservoir area cause water and soil loss on the bank slope，resulting in soil exposure and less vegetation coverage and making ecological restoration difficult.Under the combined action of external rainfall and waves，the surface soil of the bank slope in the fluctuation zone is scoured and eroded，resulting in intensified erosion and soil loss.Taking the soil bank slope in the fluctuation zone in the Three Gorges Reservoir area as the research object，this paper analyzes the erosion weight under the combined action of rainfall and waves and studies the protection performance of the terra block mat structure under the composite erosion.The experimental results show that the average erosion weight of wave factor and rainfall factor is 71.23% and 49.56%，respectively.Wave is the main erosion factor in composite hydraulic erosion.Terra block mat has great erosion resistance and can reduce the average soil loss of about 65.2% in composite hydraulic erosion，and adding a stone cage net structure can improve erosion resistance by about 20%.It has guiding significance for the analysis of similar soil erosion and the selection of revetment structures.

Abstract:Deep soft soil lies under the substratum of a ship lock，where the geological conditions are complex，and the excavation depth of the ship lock foundation pit is large.In order to meet the deformation requirements of the supporting structure and the surrounding environment and ensure the economy and safety of the ship lock construction，it is proposed to add two prefabricated steel supports into the double-row pile supporting scheme.This paper focuses on the combined support of prefabricated steel supports and double-row piles and uses the finite element software，namely GTS-NX to simulate the construction process of the deep foundation pit of the ship lock.The monitoring data and finite element analysis results show that the horizontal displacement characteristics of the supporting structure featuring prefabricated steel supports and double-row piles and the settlement characteristics of surrounding buildings are basically consistent with the measured results of the project.Steel support can effectively limit the horizontal displacement of the supporting structure and reduce the impact of pit excavation on the surrounding environment.Therefore，it is feasible to use prefabricated H-shaped steel supports to reinforce deep foundation pits in soft soil.

Abstract:The foundation of a large LNG tank area is formed by dredger fill，which is soft and liquefied seriously.According to the geological conditions and preliminary tests，we propose a variety of treatment schemes such as dynamic drainage consolidation method and local interpenetration or full lap cement mixing piles and carry out a large number of field tests.The results show that the vibratory tube sinking gravel pile can effectively improve the strength of soil between piles and eliminate the liquefaction of sandy soil within the pile length.The improved Billam method based on the effective tamping energy can better estimate the effective reinforcement depth of the gravel pile composite foundation by dynamic compaction.The dynamic drainage consolidation method is suitable for processing sandy dredger fill，whereas the foundation stiffness after treatment is far lower than that of the cement mixing pile scheme.For areas with thick soft dredger fill，the dynamic drainage consolidation method and interpenetrating cement mixing short pile scheme，and full lap cement mixing long pile scheme can greatly improve the strength of the composite foundation，which can be used in different areas according to the thickness of soft soil.For the foundation of large single buildings in the dredger filling area，it is feasible to adopt the idea of a combination of multiple schemes for zonal treatment，which is helpful to save engineering costs.

Abstract:Settlement deformation monitoring and prediction is the important aspects of building.However，because of finite cost and damage of monitoring points，settlement data often have incomplete or irregular time intervals，leading to worse predictions.In this paper，the limitation of the grey model is improved and validated with the settlement data of the deep soft clay layer of a cruise terminal project.The results show that：1) the R2 of both the improved and the common grey models are greater than 0.9，and the average error is less than 15%.2) the middle and latter part of the prediction curve of the improved grey model is closer to the settlement monitoring data than that of the common grey model.The accuracy of the improved model is higher，which proves the superiority of the new model.3) S17 has the worst accuracy，which may attribute to little settlement data and larger initial time interval.It is recommended that settlement monitoring should be as frequent and complete as possible within the cost range.

Abstract:The hydraulic reclamation technology without cofferdam is the most ideal and rapid process for land formation in open sea areas.According to mature experience in hydraulic reclamation of sandy soil without cofferdam，developing efficient and reliable hydraulic reclamation technology of clay without cofferdam is an important direction to improve the efficiency of hydraulic reclamation in open sea areas with muds.Based on a shoreline restoration project in Lianyungang，this paper proposes the hydraulic reclamation technology without cofferdam，in which the traditional mud material is replaced by a lump hard earth cake.In addition，the paper compares multiple schemes in the field test section，repeatedly adjusts construction parameters，and improves the natural drainage and settlement efficiency of soil by hydraulic reclamation.The results show that the soil layer formed based on the hydraulic reclamation of clay lumps settles rapidly within 4-5 d after hydraulic reclamation，and the main consolidation is basically completed，enabling the construction machinery to enter the site safely.After 2.5 months of natural consolidation and settlement，the bearing capacity of the foundation by hydraulic reclamation can reach more than 45 kPa.The hydraulic reclamation of clay lumps facilitates land formation，and it is conducive to energy saving，carbon reduction，and ecological and environmental protection，thus having a good application prospect.

Abstract:Regarding the urgent need of ecological reef clearing，milling method as a mechanical rock excavation method is used in underwater reef clearing.According to the field test data of milling and clearing the reef，based on the discrete element 3DEC simulation of the process of milling and clearing the reef，this paper studies the reef breaking law of different construction parameters (output torque，working pressure，knife depth，swing arm velocity).The simulation results show that the output torque and working pressure have significant influence on the operation of milling head，the over-high working pressure leads to the clamping phenomenon of the milling head.Milling head stuck tool will increase cutting resistance and affect the life of the cutter.The specific energy consumption of normal operation of milling head decreases with the increase of output torque and working pressure.The cutting resistance and milling efficiency both increase with the increase of cutting depth and swing arm velocity.The specific energy consumption of reef milling decreases with the increase of the cutting depth and has an exponential decreasing relationship with the swing arm velocity.The research results have important reference significance for the actual construction of milling and breaking reef.

Abstract:In the construction of vibroflotation piles with traditional flat barges and crawler cranes under wave conditions，there are problems of large pile position deviation，low hourly interest rate，and high potential safety hazards.Therefore，this paper proposes a technical scheme for underwater vibroflotation pile construction featuring grab dredger reconstruction with spud positioning and feed vibroflotation by transforming the dredger，improving vibroflotation equipment，and optimizing construction technology in a breakwater head transformation project in Tangshan Port，and the feasibility of the scheme is verified.The results show that the scheme meets the requirements of construction safety and pile position accuracy，and it is worth popularizing under similar working conditions.Through modular reconstruction，the application scope of the dredge is expanded.The pile quality and hourly interest rate under wave conditions are improved，and the project cost is saved.

Abstract:To construct independent piers and abutments quickly，efficiently，economically，and safely under short working time and discontinuous sea conditions，full rotation piling barges are applied to sink piles；construction platforms are set up on the caisson cover plate；crawler cranes are utilized to lift the column reinforcement cage and steel formwork；motor controlled hoppers are adopted to open and close the column concrete；long-arm hook machine is used to transport concrete to the chute on the transport barge to pour the pier and abutment concrete.By taking a series of measures，we guarantee the construction period，save cost，improve work efficiency，and ensure the safety of personnel.In addition，the construction experience of independent piers and abutments under severe sea conditions is accumulated for reference of similar projects.

Abstract:For the poor quality of rotary jet piles in the sea artificial island environment and the superposition of deep riprap layer，combined with an actual project of the east artificial island of the Shenzhen-Zhongshan Bridge，we carry out a two-stage study on the construction technology of rotary jet piles based on the process test to verify the water stopping effect by water pumping and recovery tests and optimize the subsequent enclosure structure form.The results show that the rotary jet pile construction method combining rotary excavation for filling and rotary spray grouting combined and adopting dynamic control of slurry lifting speed based on theoretical calculation formula is effective，which can effectively solve the construction problems of slurry loss in the riprap layer.The enclosure structure form combining infill pile and inter-pile water stop rotary jet pile can meet the water stop demand of the pit excavation and can eliminate constructing the external waterproof curtain.

Abstract:When the vibroflotation method is used to treat the fine sand foundation，the construction process and construction parameters have a great influence on the final foundation treatment effect.This paper carries out field vibroflotation tests with different construction parameters for dry，loose，and fine sand in a port project in Peru，South America and conducts standard penetration tests to compare the density changes of the dry，loose，and fine sand at different positions before and after vibroflotation.When dry，loose，and fine sand is reinforced，the traditional vibroflotation process has the problem of insufficient density at the top.Therefore，this paper analyzes the causes of the defects and puts forward the construction improvement measures of “partial filling，timely backfilling，water pressure reduction，and layered counter-insertion”.The results show that the improved vibroflotation construction process can effectively reinforce the loose backfill fine sand.

Abstract:Regarding the problems such as extrusion damage of prefabricated blocks and low construction efficiency in the soft mattress for bank revetment of J002-1 section of the Yangtze River to Huaihe River diversion project，we optimize the original design scheme of soft mattress structure for bank revetment and construction method.We adopt the soft mattress structure of C25 concrete prefabricated blocks interlock sheet and the construction method of geotextiles-laying boat by referring to engineering examples and scheme comparison and selection.The results show that the optimized construction scheme is technically feasible，the prefabricated blocks have the advantages of less damaged and high construction efficiency，and the expected effect is achieved.The successful application of soft mattress structure optimization and geotextiles-laying boat construction method in the Yangtze River to Huaihe River diversion project provides a good demonstration for similar projects and has good popularization and application value.