Abstract:Marine dredged slurry generally features fine particles，high moisture content，and poor permeability. The flocculant vacuum preloading method can increase the reinforcement effect of marine dredging significantly. However，at present，the flocculation and consolidation characteristics of marine dredged slurry in Bohai Bay are unclear. This paper investigates the flocculation and consolidation characteristics of marine dredged slurry after pre-treatment with CaO and APAM based on the mineral composition and physical properties of the Dongying reclamation soil. The results show that the dredged slurry in the area is silty and clay，with quartz and calcium carbonate as the primary mineral components and some clay minerals such as muscovite and chlorite. The flocculation rate is speedy after adding organic flocculant APAM with an amount between 100 and 300 g/m3. It only takes about 5 minutes to complete the solid-liquid separation and discharge an extensive amount of supernatant. The volume of the final supernatant increases by 1/4-1/3 compared with that without flocculant. The addition of inorganic flocculant CaO also speeds up solid-liquid separation. However，the volume of supernatant is less than that without adding flocculant，which differs entirely from the organic flocculant. The consolidation coefficient of the dredged slurry will increase to different degrees after adding flocculants：The consolidation coefficient rises as the organic flocculants are constantly added to the dredged slurry. However，the inorganic flocculants are different：The consolidation coefficient increases first and then decreases with the increase in the added amount. The optimal added amount should be adopted to get the best consolidation effect. The research results are of great theoretical significance for vacuum preloading treatment of marine dredged slurry in Bohai Bay.

Abstract:We use the VOF（volume of fluid）method to trace the water surface，simulate the wave generation by the wave paddle method，establish a numerical wave tank to study the relationship between wave transmission coefficient and various influencing factors of the closely arranged pile breakwater，analyze the influence of pile diameter，clear distance，perforated ratio and wave steepness on wave transmission coefficient，and establish a formula for calculating wave transmission coefficient of closely arranged pile breakwater by regression analysis based on the results of the numerical simulation and the physical model test. The results show that the wave transmission coefficient of closely arranged pile breakwater decreases rapidly at first and then slowly with the increase of pile diameter，and increases rapidly at first and then slowly with the increase of clear distance and perforated ratio. In the case of submerged，the transmission coefficient increases with the increase of submerged degree and tends to be stable. In the case of non-submerged，the transmission coefficient increases at first and then becomes stable with the increase of the gap between freeboard height and water level. The wave steepness has no obvious effect on the wave transmission coefficient.

Abstract:To master the incipient motion of newly deposited fine sediment under different saline conditions，we carry out three series of mud incipient tests with circulating flume，including salt-free mud incipient motion tests in saltwater（saltwater-salt-free mud），salt mud incipient motion tests in saltwater（saltwater-salt mud），and salt mud incipient motion tests in freshwater（freshwater-salt mud）. On the basis of the particle image velocimetry（PIV）system and digital image gray processing technology，we identify quantitatively the critical incipient velocity of sediment. The results show that the higher salinity of water body or cohesive sediments makes it more difficult to start. There is a logarithmic relationship between the incipient velocity of cohesive sediments and the salinity of water or cohesive sediments. The incipient velocity increases sharply at the salinity of 0‰-10‰ and slowly at the salinity of 10‰-40‰. For the same salinity，the incipient velocity of salt mud in freshwater is the highest，followed by that of salt mud in saltwater，and that of salt-free mud in saltwater is the lowest. For sandy silt mixtures containing gravel，it is easy to flocculate in saltwater. However，the flocs are easy to disperse under high-speed stirring at 520 r/min，so salinity has little effect on the incipient motion of sandy silt.

Abstract:A series of flume experiments are conducted to study the influence of the seaward-side slope of a levee on the discharge of combined wave and surge overtopping under extreme sea conditions. By comparing the discharges under different seaward-side slopes，this paper analyzes the influence of the seaward-side slope on the discharge of combined wave and surge overtopping. The following conclusions can be drawn from the study：1）In the range of -0.6＜Rc/Hm0＜0，the discharge of combined wave and surge overtopping is significantly affected by the seaward-side slope of the levee. 2）Within this range，when the seaward-side slope of the levee changes from 1∶1.5 to 1∶4.25，the discharge of combined wave and surge overtopping under the same wave condition first decreases and then increases slightly. With the experimental results as a basis，an empirical formula for the discharge of combined wave and surge overtopping considering the seaward-side slope of a levee is proposed to provide a reference for the safety assessment and protection of levees under extreme conditions.

Abstract:For the ecological needs，a hydrodynamic environment with specific requirements needs to be created in the ecological reef group，and the inside structure cannot be blocked. This is realized by the reasonable layout of reefs under the action of waves in the siltation-type intertidal zone. For three layout patterns of grid surfaces aligned facing the waves，hollow surfaces aligned and staggered facing the waves，cross-section physical model tests are conducted to study the flow pattern and velocity distribution in the ecological reef site. The results show：1）Under the action of waves，the flow fields inside and outside the reef structure are all three-dimensional，and the velocity attenuation at each point in the reef group is generally uniform. 2）The velocity of hollow surfaces aligned facing the waves attenuates to 0.5-1.0 m/s under normal wave conditions，which well meets the requirements of the flow velocity in the ecological reef site.

Abstract:The durability of reinforced concrete caused by chloride salt under high temperature，high humidity and high salt environment in South China is a major problem. A hydrophobic surface structure of concrete provided by silanes impregnated helps to reduce the depth of chloride penetration. Previous studies are all based on laboratory and exposure tests. However，there is little reported information about the long-term corrosion protection of silane impregnated concrete in South China marine environment. Herein，the water absorption，chloride content and corrosion potential test are applied to assess the corrosion protection of silane impregnated concrete after 12 years’ service. The results indicate that the silane treated concrete surface is compact and intact，while the hydrophobic performance is degreased with the increased service life. The limited diffusion rate of chloride in concrete and strong passivation of steel rebar resulted from silane contribute to a significantly improved durability of concrete structure.

Abstract:We carry out a laboratory comparative test of the solidification effects on dredged sludge under slag and lime contents of less than 20%. We test the moisture contents，pH values，and mechanical strengths of samples of different ages，and investigate cost and environmental friendliness to comprehensively evaluate the solidification effects of slag and lime. The results show that the water consumption capacity of slag is slightly higher than that of lime. When the slag content exceeds 12%，the pH value and shear strength of the sludge do not increase anymore，and the increase in the unconfined compressive strength after 7 d accounts for a large proportion. When the lime content is above 2%，the pH value of the sludge remains at 12，and the unconfined compressive strength shrinks. When the lime content exceeds 6%，the shear strength of the sludge no longer increases. Under the same content，the effects of lime in improving the pH value，cohesion，and early strength of sludge are better than those of slag，although its effect in increasing the internal friction angle is poor. The content of lime needed to meet the landfill requirements is only half that of slag，so lime is more cost-effective.

Abstract:Port concrete generally suffers from chloride diffusion. To evaluate the resistance of mortar to chloride diffusion under different instantaneous loads after aggregate pretreatment，we coat the aggregate with slag powder and silica fume slurry respectively to change the roughness of aggregate. We then test the chloride migration coefficient of samples after an instantaneous load. The experimental results show that the interface performance of the aggregate is improved after pretreatment. The chloride diffusion coefficient of the mortar prepared by the pretreated aggregate is lower than that of the untreated aggregate，and the coating effect of silica fume is superior to that of slag powder. A larger load leads to a higher chloride diffusion coefficient，which endows the silica fume-coated aggregate after loading with the best resistance to chloride diffusion.

Abstract:For terminals located in extremely cold seas，to be operated uninterruptedly in the whole year，appropriate ice control measures shall be taken，and ship mix shall be arranged accordingly for the throughput demand. An ore loading dock project in the arctic area of Canada is taken as an example in this paper. Based on the natural conditions，ice conditions and operation requirements，this paper proposes applicable ice ship class，ice control measures such as ice management vessels and air bubbler system，as well as ship mix for the annual throughput. Berth occupancy is also calculated to demonstrate the proposed ship mix. The proposal of this paper can provide reference for the design of similar projects.

Abstract:In order to study the influence of the covered pile on the front wall，anchor wall and lever force performance of the sheet-piled wharf under seismic action，we carry out the dynamic finite element analysis of covered sheet-piled wharf of the 32# berth of Jingtang Port by ABAQUS software. The results show that the covered pile can significantly reduce the front wall bending moment and rod tension under the seismic action，and the influence on the force performance of the anchor wall is small. The thickness of the covered pile has a great impact on the rod tension and bending moment of the front wall below the mud surface elevation，and has a small effect on the front wall bending moment above the mud surface elevation and anchor wall bending moment. The front wall bending moment above the elevation of the mud surface line increases gradually with the increase of the spacing between the front wall and the covered pile，and the spacing between the front wall and the covered pile has no obvious effect on the front wall bending moment below the elevation of the mud surface line，anchor wall bending moment and rod tension. The length of the covered pile has less effect on the force performance of the front wall，anchor wall and lever under seismic action.

Abstract:Asphalt pavement mostly has a structure of a surface layer of asphalt mixture and a base layer of cement bound granular mixtures（CBGM）. However，underdeveloped regions overseas are often without stable material supply and unable to build CBGM batching plants by themselves and maintain the quality and progress of CBGM construction. A suitable substitute material for CBGM needs to be chosen to tackle this problem. A graded granular material is adopted as the substitute material after a comprehensive analysis of factors such as adaptability and raw material availability，and the conversion factor is analyzed properly to optimize the thickness of the graded granular material layer. In this way，construction difficulties and risks can be significantly reduced，and quality，progress，and cost of construction can be controlled. This paper，taking a port project in South Asia that adopts a pavement structure of asphalt and the graded granular material as an example，describes the application of such pavement structure in underdeveloped regions overseas. According to the implementation result，the graded granular material has a good capacity of compaction，no cracking or rutting is observed on the asphalt surface，and no observable differential settlement of the road occurs.

Abstract:A project is constructed on island reefs，with poor wave cover conditions，strong tidal currents，and high sediment content，which is extremely unfavorable for the construction of a land-island transportation wharf. Therefore，the key technical difficulty in the water layout of this project is to find ways to cover the harbor basin，adjust currents，and reduce sediment deposition. Through the analysis of harbor construction conditions and model simulations，we put forward a design scheme of combining the close pile breakwater with the hydraulic structure of the wharf. During the construction of the project，the project has withstood the tests of typhoons and cold waves with good wave blocking effects. In this way，the construction difficulty is solved，and new design ideas are provided for the development and utilization of similar shorelines.

Abstract:The overburden of the Yellow River-crossing scheme of the Beijing-Hangzhou canal is deep，and the water level of the aqueduct of the upper span scheme is more than 30 m above the ground on both sides of the river. Aiming at the multi-level scattered staggered water saving basins of high water head lock at both ends of aqueduct，two kinds of layout schemes of chamber-basin are put forward，which are wall back high fill type and wall back low fill type. We use ABAQUS finite element software to build plane finite element models，research the spatial-temporal variation characteristics of the settlement of the chamber-basin and the bending moment of the floor of the lock chamber during the construction and service periods，and discuss the action mechanism of the high fill on the lock chamber. The results show that：1）Under the condition of natural foundation，the settlement of the chamber-basin in the two layout schemes is relatively large，and the negative bending moment of the floor generated by the drag down force and side load of the high fill on the back of the wall basically counteracts the positive bending moment generated by the soil pressure，which leads to the little difference of the bending moment of the floor in the two schemes and is always controlled by the negative bending moment. 2）The foundation treatment method is one of the key technical problems to reduce the settlement of the chamber-basin and improve the stress condition of the lock chamber. 3）The method of multi-pile combination treatment of lock chamber and wall back filling and the method of drainage consolidation preloading of the filling outside foundation pit are worthy of further study.

Abstract:The sinking of flexible mattresses，due to ship movement，water flow，and other factors，is prone to tearing of the mattresses. To explore the influences of relative displacement of the ship，water depth，surface velocity，and arrangement of stiffeners on the forces on downstream sinking flexible mattresses，we build a mathematical model of flexible mattresses according to the catenary theory，and carry out a series of numerical calculations considering the exponential distribution of velocity along water depth. The results show that the relative displacement of the ship，followed by surface velocity and water depth，has the greatest influence on the stresses of flexible mattresses. The maximum axial and transverse stresses are both at the top of the flexible mattresses，and a characteristic of large tensile forces at two ends and small ones in the middle is observed along the mattress width direction. The arrangement of stiffeners can significantly reduce the axial and transverse stresses of the mattresses and thereby prevent the tearing phenomenon.

Abstract:We Collected measured data and analyzed the variation characteristics of the hydrological elements in the Yangtze River Estuary，such as the discharge of Datong station and the velocity of the North Passage middle station from 2016 to 2019.The results show that：1）The annual total runoff volume of Datong Station in recent four years is close to the average of previous years. The maximum monthly average flow occurs from July to August，and the minimum occurs from October to February. 2）The monthly averages of high and low tide，tidal level and tidal range in the North Passage middle station have a single-peak distribution during the year，and the peak occurs from August to October. The changing trends of the 3 different stations are basically the same. The monthly average tide level in the east of the South Passage station is the highest and the tidal range is the largest. 3）The monthly mean value of the ebb current is larger than that of the flood current in the North Passage middle station and reaches the peak from June to August. The flood current reaches the trough from June to August. The monthly average velocity of ebb tide is larger than that of flood tide. The average monthly velocity of flood tide reaches its minimum in July. The monthly average duration of low tide is larger than high tide and reaches the peak form June to August. 4）The water temperature in the North Passage middle station has an obvious change during the year. The monthly average temperature in August can reach 29.96 ℃，and the monthly average temperature in February is 7.51 ℃. 5）The monthly average effective wave height and period of the east of the South Passage station，Niupijiao and Yangtze River Estuary are basically the same. From the perspective of annual distribution，the effective wave height changes greatly and the wave period changes little. The effective wave height and wave period of the Yangtze River Estuary station are higher than those of the other two stations. The difference between the significant wave height and wave period of the east of the South Passage station and Niupijiao is small. The total wave energy of the three stations is the smallest at the east of the South Passage station and the largest at the Yangtze River Estuary.

Abstract:In order to study erosion-corrosion distribution of contact block surface for miter gates，we extract a partial contact block model，simplify the model，and compare and analyze the influence of different particle size，mass flow，and upstream water pressure on the distribution of the erosion area for the contact block. The results show that the wear of the concave block for miter gate is faster than that of the convex block. The erosion area of the larger sand size is mainly at the entrance of the upstream crevice，the erosion area of the medium sand size is more evenly distributed，and the erosion area of the smaller sand size is mainly at the exit of the downstream crevice. The sand particle size has a greater influence on the wear position distribution of the contact blocks，and the influence of the mass flow and upstream pressure on the wear position distribution of the contact blocks is the second.

Abstract:In view of the limited draft of the Gezhouba Dam Sanjiang ship locks during the dry season，this paper puts forward a thought of excavation extension and a development scheme for Gezhouba Dam Sanjiang downstream navigable channels that take into account the construction of the new waterways of the Three Gorges Hydro-junction. Comprehensively considering the representative ship type in the new channel design and the traffic flow in the Sanjiang navigable channels，this paper analyzes and calculates the scale requirements of the Sanjiang navigable channels and investigates the improvement degree of the passing capacity of the Gezhouba Dam Hydro-junction and the impact on navigation benefit after the deepening of the Sanjiang downstream navigable channels. The implementation of the project will increase the annual throughput of the Gezhouba Dam Hydro-junction by approximately 6.698 million t and yield a direct economic benefit of 335 million CNY/a.

Abstract:Aiming at the problems of the flow velocity fluctuation process caused by the unsteady flow of ship lock discharge，especially the relationships of the hydraulic factors in the restricted middle navigable channel，the transformation of unsteady flow and the corresponding scales，we study the relationship between the unsteady flow discharge process of ship lock and the flow velocity fluctuation process in the restricted middle channel through systematic experiments of physic model based on the restricted middle navigable channel of Baise navigation project. The results show that the main reasons of the generation of unsteady flow discharge wave are attributed to insufficient energy dissipation，the rapid increase of discharge during the ship lock discharge process，and the limited boundaries，which cause the flow fluctuation. By reducing the peak value of the fragmented time-discharge curve，the maximum velocity and maximum inverse velocity decrease. In the long restricted middle navigable channel，due to the energy consumption，the velocity fluctuation in the downstream is much smaller than that in the upstream，which still exists after the flow pattern reaches a steady state.

Abstract:According to the characteristics of river flow and the calculation precision and efficiency of the model，the one-dimensional flow mathematical models of the Yangtze River usually divide the river channel below Yichang into two sections with Datong as a boundary. The runoff model is built from Yichang to Datong and the tidal current model is built from Datong to Liuhekou. However，under new water and sediment conditions and complex river and lake networks，the traditional two-section model can hardly simulate the long river section of complex river networks as a whole. In response，a one-dimensional flow mathematical model for the river network is built based on the high-precision and high-performance finite volume method. It solves the interface flux of adjacent units by SLIC and simplifies the calculation of coefficient matrix with the control body as the calculation unit for the intersection of complex river networks. The physical process of the model is clear with convenient and fast calculation. The one-dimensional flow mathematical model is applied to the section from Yichang to Liuhekou. The results show that the model is stable with high precision and effectively realizes the digital-model integration of the trunk line of Yangtze River below Yichang.

Abstract:In view of the long running time of some mechanisms in the operation process of the Three Gorges ship lift and its influence on the operation efficiency of the ship lift，we carry out research on optimizing the operation process of the ship lift. According to statistical analysis and theoretical calculation，when the water level difference between the upstream and downstream channel is smaller than a certain range，the pipeline water pumping sequence affects the operational efficiency of the ship lift. In light of long-term operation and management experience，we propose an optimization plan for the pipeline water pumping process of the Three Gorges ship lift and conduct safety argumentation and efficiency analysis. The results show that under the existing conditions，the operation time of the ship lift is saved by about 70 s per compartment after process optimization，which greatly improves the operational efficiency of the ship lift.

Abstract:In view that temporary navigation channels need to be opened up during the expansion of the navigable aqueduct of Binhai Hydro-junction Phase II for continuous navigation，following the requirements on channel network planning，we consider combining temporary navigation lock with permanent use. According to the requirements on route organization，current situation and prediction of ship type，freight volume prediction，and safe navigation of ships in the construction navigation period and permanent navigation period，we determine the scales of the navigation locks combining permanent and temporary use，the channel scale of the temporary connection section，and the navigation layout scheme. Then，we analyze the navigable flow conditions at different parts in terms of river topography，flow rate，and water level in different periods. The results show that the navigable flow conditions of the proposed layout scheme all meet the requirements. On the basis of the characteristics of the project，the key research directions in the next stage are proposed，and they can serve as a reference for the layout of similar navigation schemes combining permanent and temporary use.

Abstract:Considering the difficulty of rigid structures in adapting to local scour deformation，we study the flexible siltation-promoting structure and propose a bionic flexible siltation-promoting beach protection structure. The structure’s effect of erosion prevention and siltation promotion is investigated under different inflow conditions and arrangement modes by movable bed experiments in flumes，the result of which shows a satisfactory effect. Applying the research results to the waterway regulation project of the Hanjiang River estuary，we further test the research results by field application. The results indicate that the structure has good integrity. In addition，the engineering effect in the application area is consistent with the model test data，and thus the expected goal of beach protection and siltation promotion has been achieved. This structure enriches the siltation-promoting structure forms in waterway regulation projects with a good application prospect.

Abstract:Due to the influence of the meteorological environment，the water area drilling operations in the field work of the channel engineering survey caused the exploration ship to deviate from the designated location area and could not be early warning in time. In the actual control of the project，there is weak information service capability and the inability to visually and effectively trace the business data in the project implementation process，etc. We study Beidou/GNSS，BIM，GIS，and fully combine the advantages of Beidou/GNSS in positioning and BIM in information transmission and sharing，and rely on a certain waterway engineering survey project to explore and verify early warning，business data management and control. Practice has proved that the comprehensive use of BIM，GIS and Beidou/GNSS positioning data in waterway survey management and control can improve the ability of early warning and information service.

Abstract:The inland waterway regulation works have the characteristics of long lines as well as multiple areas and concealed works，and they are exposed to problems such as difficulties in construction quality tracing and process control and low efficiency of construction management. In view of the key difficulties in the construction of inland waterway engineering，we realize the in-depth creation of building information modeling （BIM）and integrated application of the multi-source model by using corresponding intelligent construction equipment. Relying on the waterway regulation project of the Yangtze River Estuary of the Beijing-Hangzhou Grand Canal，the modeling and integrated application are based on the BIM technology and intelligent construction site management platform. In addition，we have solved typical problems such as mass concrete pouring，long-line construction process control，process inspection of complex concealed works，as well as construction and monitoring data management，realized the integration of the BIM technology and management platform in the construction stage，and improved the construction quality and technical management level of engineering construction projects.

Abstract:In view of the complex and changeable environment during construction of waterway improvement projects，and the difficulty of information sharing and transmission between organizations，this paper uses BIM technology in the dynamic control of the waterway regulation projects to achieve the intuitive display，efficient query and sharing of engineering construction information，and thus provide scientific and necessary technical support for project dynamic decision-making，so as to better cope with the complex and changeable environment in the course of waterway regulation and ensure the realization of construction goals. Relying on the 6-meter-deep waterway regulation project in Wu’an section of the Yangtze River，the real progress，quality and investment information are associated with the modular model to achieve effective dynamic control of the three goals of the waterway improvement project.

Abstract:To tackle the problems that the efficiency of manual monitoring is not high，and its monitoring frequency cannot satisfy the requirement of foundation pit monitoring under extreme weather，we test the reliability of an automatic monitoring method，with manual monitoring adopted for regular comparison. The results show that the monitoring values of the static level are similar to those of the electronic level. The resulting curve of the fixed inclinometer is nearly the same as that of the sliding inclinometer，and the curve shape is consistent with site construction conditions. The automatic monitoring has good reliability in foundation pit monitoring. For foundation pits subject to complex stress states and frequent bad weather，automatic monitoring should be the first choice for their monitoring in the case of a controllable cost.

Abstract:Taking the marine soft soil of a port foundation in the Pearl River Delta as an example，we carry out the triaxial shear creep tests of consolidated drainage and consolidation undrained respectively. Based on the results of shear creep tests and the traditional Burgers model，we introduce a nonlinear SP element，obtain a new one-dimensional creep constitutive model after series connection，extend it to three-dimensional case，use the improved model to fit the shear creep curve of marine soft soil，and verify the rationality and correctness of the model. The results show that the marine soft soil shows instantaneous elastic deformation at each moment of loading，and then shows the stage of decay and stable creep，and the last stage of loading marine soft soil has accelerated creep. The axial strain and pore water pressure of each loading level are higher than these of drainage condition. The permeability of marine soft soil affects creep deformation，and the weak permeability condition is more conducive to the accumulation of creep deformation. The improved Burgers model is used to fit the shear creep curve of marine soft soil，which is in good agreement.

Abstract:Based on the design requirements for drainage and liquefaction mitigation of stone column，the soil densification between columns and the diameter at any depth should meet the design index requirements after construction. In order to verify constructionability of different equipment on coral reef sand strata and obtain suitable process control parameters and quality control procedures，the field trial test has been performed to compare the pile quality of the vibro-flotation process and the vibrating tube process，and to analyze the difference of soil compaction effect between the piles. The results show that：1）On coral reef sand strata，there is little difference in the compaction effect between the vibro-flotation process and the vibrating tube process. 2）To ensure the compaction effect of soil between piles and the quality of piles，the vibro-flotation process should be controlled by three indicators：the amount of segmented filler，the reverse -insertion compaction current and the real-time pile diameter chart.3）The vibrating tube process should be controlled by the amount of segmented filler，and the relatively loose layer should be identified in combination with the hole-making compaction current. Measures such as increasing the vibration retention time，increasing the reverse-insertion depth and slowing down the reverse-insertion speed are taken when the loose layer is formed into piles.

Abstract:A wharf project in the southern area needs to be set up a large flood-relief channel in the port area. Restricted by the reclamation policy，the project has a relatively small storage yard. The surface soil layer is silt and silty soil with a thickness of about 20 m，which requires ground consolidation. We compare and select the structure of the flood-relief channel，use cement mixing piles to strengthen the soft soil foundation，recommend the steel sheet pile structure because of its fast construction speed and without foundation pit，give the reasonable suggestions for the calculation method of sheet pile strengthened by cement mixing pile，and compare and check the two strengthen schemes of sheet pile wall by PLAXIS software. The results show that the reinforced body of the cement mixing pile can be considered as a rigid body，which can avoid unsafe condition caused by excessive consideration of solid addition. The reinforcement scheme in front of sheet pile wall is more favorable than that behind sheet pile wall.

Abstract:In order to adapt to the large-scale development of dock，it is necessary to carry out innovative design research on the dock wall structure of ultra-deep dock. At present，there are few cases of using lattice diaphragm wall structure in dock wall of ultra-deep dock，and further research on its force characteristics and stability is still needed. Based on an example of an ultra-deep dock project in the Yangtze River estuary，we verify the advantages of greater rigidity and less displacement of the lattice diaphragm wall than the traditional retaining structure through the calculation of the finite element model and measured data，clarify its applicability in ultra-deep dock，and carry out the sensitivity analysis of factors such as the depth of the partition wall and the front wall in the lattice diaphragm wall. The results show that the internal force of the front wall can be reduced by appropriately reducing the depth of the partition wall. The insertion depth of the front wall is not as deep as possible，the appropriate reduction of the depth can make the structure more uniform.

Abstract:The installation technologies for large-scale box culverts adopted in the artificial island of Hong Kong-Zhuhai-Macao Bridge-Hong Kong Boundary Crossing Facilities（HKBCF）are sectional prefabrication and floating transport. To avoid the leakage of box culverts during floating transport，we carry out structural design，calculation，and verification for the leakproof structure of box culverts（with steel seal doors）and optimize the leakproof structure on the basis of watertightness tests. The result shows that the above sealing technology is feasible，and no seepage or leakage is reported for 29 sections of prefabricated box culverts during floating transport. Moreover，the technology significantly improves the construction efficiency and reduces the construction cost，which may serve as a reference for similar projects.

Abstract:To address the low efficiency of cutter suction dredgers in dense sand and silt of coastal ports in China，we carry out an experimental study on the excavation of dense silt and obtain the excavation resistance characteristics of the dense silt. According to the cutting characteristics of high-power cutters for dense sand，we optimize the section shape of cutter arms and establish a three-dimensional（3D）model of cutters to analyze their stress when cutting sand and their stress and deformation at the maximum power. On this basis，we develop a dense sand cutter. The application of the research results in a cutter suction dredger shows that the productivity of the dense sand cutter is significantly higher than that of the original ones under the same working condition.

Abstract:The trailing suction hopper dredger（TSHD）that has different characteristics of the ship type is affected by wind，current and swells. Its wiring and the rake head will be changed from time to time to directly reduce the excavation quality and dredging the shallow point. Taking the phase I project of the deep-water channel in the southern area of Shijiu Port，Rizhao Port，we improve the equipments，carry out the effect analysis of different construction methods adopted for different shallow points，and summarize a set of dredging shallow point construction technology for TSHD. The results show that improving rake teeth，vertical plate，and making plough can effectively solve the problem of low dredge shallow point efficiency of TSHD，and be popularized and used in the similar projects.