Abstract:To comprehensively and systematically analyze the advantages and disadvantages of various existing artificial armour units，the development of representative artificial armour units is introduced，and the stability principle of armour units is analyzed. The stability coefficient KD and stability number Ns of mainstream armour units are summarized and compared，which are used to evaluate the stability of blocks，and the amount of concrete per unit area and the number of blocks are introduced to evaluate their economy. On this basis，6 common artificial armour blocks are selected，and their stability and economy are quantitatively compared. Meanwhile，based on foreign standards and results in the cutting edge of armour units，suggestions on calculation and usage requirements of Chinesepode recommended in JTS 154—2018 Code of Design for Breakwaters and Revetments are proposed. Finally，it is concluded that the quantitative comparison results of the stability and economy of the commonly used artificial armour units can be used for reference by designers when comparing and selecting armour units. We put forward some suggestions for the use of the Chinesepode in the national standard，so that Chinese design enterprises can better connect with foreign customers.

Abstract:To explore the influence of embankment on wave propagation deformation in the island reef system，we use the non-hydrostatic wave model SWASH to verify and compare the three-dimensional island reef model test data，and then build breakwaters with different lengths at different positions above the island reef for wave current simulation. The results show that the wave height in the characteristic section of reef flat does not change obviously with the construction of embankment，but the increase and decrease of water changes obviously with the construction of embankment. The longer the embankment length and the larger the embankment distance，the greater the water increase in front of the embankment and the wider the range of water increase. The wave height and increase/decrease water in the fracture characteristic section change obviously with the embankment construction. The longer the embankment length and the smaller the embankment distance，the smaller the wave height in the section，and the more stable the increase/decrease water. The research results can provide reference for similar reef top engineering constructions.

Abstract:Sediment scouring experiments are conducted for upstream，downstream，laterally inclined and vertical circular piles under constant water flow conditions. The empirical equation of scour depth-time is used to fit the equilibrium scour depth，then the maximum scouring depth of piles with different inclined directions，the development of scouring deposition and the final distribution of scouring and depositing patterns are studied. The experiment results show that：1）The lateral scouring range of the inclined pile is smaller. Compared with the vertical pile，the maximum scouring depth of the downstream inclined pile reduces 16.89%，and the depositing length after the pile is shortened. 2）The maximum scouring of the lateral inclined pile is located in the inclined direction，and its depth increases 6.92%. The scouring and depositing shape develops to the inclined side，and the depositing area behind the pile is narrow and long. 3）The maximum scouring depth of the upstream inclined circular pile increases 15.62%，and the scouring area develops upstream with the highest post-pile depositing height and the longest longitudinal scouring length.

Abstract:Based on the importance of hydrodynamic conditions in the study of marine engineering construction in coastal zone，the hydrodynamic environment of Zhoushan Islands is particularly complex due to its vertical and horizontal waterways and dense islands. In order to grasp the influence of regional engineering construction on the sea area，we carry out a two-dimensional numerical simulation study on the evolution process of tidal current field in Dinghai sea area of Zhoushan Archipelago based on the measured data. On this basis，we analyze the tidal current field during high tide and low tide and the distribution of scouring and silting in detail in a wharf area of Panzhi Island in Dinghai. The results show that on the whole，the tidal current pattern of the surrounding sea area is not changed greatly after the project. Only within 1 500 m around the wharf，it is mainly affected by the reverse tidal current of the wharf and the nearby shipyard，and the flow direction is reversed. The flow velocity in a small area of the project is changed by the flow resistance of the wharf. The flow velocity on the north and south sides of the wharf and the north side of Xixie Village Island shows a trend of decrease and increase respectively. Affected by local projects，the overall change area of scouring and silting is mainly concentrated in the sea area around the wharf. Among them，the silted sea area is mainly concentrated near the wharf and on the east and west sides of the shipyard. The scour area is mainly concentrated in the catchment area at the corner of Panzhi Island and Xixie Village Island.

Abstract:Focusing on the impact of frequent typhoons along the coast of Fujian on the construction of port and waterway engineering，this study builds a numerical Simulating Wave Nearshore（SWAN）model with the European Center for Medium Weather Forecasting（ECMWF）background wind field and the Holland model wind field superimposed as its driving wind field and simulates the typhoon waves caused by the 201808 Typhoon “Maria” numerically. By translating the path of “Maria”，it selects Zhangzhou，Quanzhou，and Ningde as three typical typhoon landing points along the coast of Fujian and derives three idealized typhoon paths. The results yield the following conclusions：1）As the typhoon center approaches the coast of Fujian Province from the Pacific Ocean，the significant wave height in the sea area near each feature point increases first and then decreases. 2）Concerning each typhoon path，the wave direction of the sea area on the left side of the path changes from south-southwest（SSW）to north-northeast（NNE），while that on the right side of the path changes from SSW to west-northwest（WNW）. 3）A typhoon center closer to Fujian Province corresponds to a faster wave direction change at each feature point. 4）The response to typhoon path translation has reference value for optimizing the typhoon prevention scheme of port and waterway engineering.

Abstract:A large amount of abandoned dredged silt generated by river dredging needs to be effectively disposed of，while the traditional cement curing agent is a material with high energy consumption and high carbon emission，which is not consistent with the current ecological concept. With mineral powder as the main raw material and sodium silicate as alkali activator to prepare a new type of low carbon geopolymer cementing material solidified silt as engineering filler，we carry out an experiment and analysis of the mechanical property and compressive property of geopolymer solidified soil. The results show that compared with the solidified soil with 10% cement content，the unconfined compressive strength of geopolymer solidified soil with 10% mineral powder content increases by 406.1% for 28 d，and the failure form of solidified soil changes from plastic failure to elastic failure. The stress-strain curve shows obvious stress peak，which could better meet the needs of common filling materials. It has good ecological benefit and broad application prospect. Thus it can provide an effective way for recycling dredged wastes.

Abstract:The batter pile of pile-supported wharf has large stiffness and is prone to brittle failure under earthquake to cause the damage of wharf structure. As a mature technology to improve the seismic safety of the structure，seismic isolation technology has been widely used in buildings，bridges and other structures. Therefore，we add rubber isolation bearing at the top of batter pile to improve the seismic safety of wharf structure. Taking the coastal beamless slab wharf as the research object，we build the finite element analysis models of all-plumb-pile wharf structure，non-isolated batter pile wharf structure and isolated batter pile wharf structure by SAP2000 software，carry out the two-dimensional Pushover comparative analysis of the three structures，and compare and analyze the five aspects of natural vibration period，static Pushover curve，plastic hinge，pile bending moment and displacement capacity. The results show that the isolated batter pile wharf structure has large horizontal bearing capacity and displacement capacity，which can effectively solve the problem of brittle failure of batter pile.

Abstract:For improving the utilization rate and production efficiency，large petrochemical wharves often have a wide range of berthing and concurrent berthing ship types，i.e.，there are many types of ships served by the wharves and there are large differences in ship tonnage and ship size. When the auxiliary berthing facilities are not arranged properly，small ships may get stuck or sway，tilt or even roll over under the action of strong wind and waves，which is very easy to cause berthing accidents and seriously affects the safe operation of the wharf production system. Based on the actual case，this paper expounds the safety hazards and rectification and maintenance scheme for the large petrochemical wharf with small ships. The engineering practice shows that on the premise of ensuring the integrity of auxiliary berthing facilities，the safety hazards of small ships berthing can be eliminated by increasing the horizontal berthing point and the layout range of vertical rubber fenders or limiting the scale of berthing ship type.

Abstract:The reasonable elevation of wave walls and land formation is a key technical issue for successfully implementing LNG project，and its determination directly affects the protection effect and engineering quantity of the rear gas storage tank areas of LNG terminal and then the project investment and decision. With the Yangjiang LNG terminal project as an example，the project adopts a revetment zoning design with direct and indirect cover tank areas，which effectively reduces the engineering quantity in protection. Under the premise of moisture-proof and wave-proof requirements for LNG gas storage tank areas，this paper proposes an elevation linkage optimization design method for wave walls and the land formation，and the method is the most cost-effective and considers the landscape corridor. This paper carries out four groups of physical model tests of flume sections with different elevations under regular waves to verify the rationality of the elevation optimization design. The control tests of wave overtopping rates of wave walls with different structures show that the wave overtopping rate of a curved wall is smaller than that of a vertical wave wall，and thus the curved wall can be regarded as the optimal structure.

Abstract:By investigating a certain inland river port project，this paper studies several difficulties in the technological design of water intake pump houses. To reduce the sediment deposition in the inlet pipe，this paper adopts the calculation formula for the non-deposition flow velocity of sediment to determine the flow velocity in the inlet pipe. Considering that the current Standard for Design of Outdoor Water Supply Engineering fails to specify the design elevation of a water intake pump house located at the front of a wharf，this study carries out a comparative analysis of the relevant codes and presents a determination principle. The results show that when the inlet pipe is short and the hydraulic loss is small，the personnel concerned can increase the flow velocity in the inlet pipe to a proper extent according to the calculation formula for the non-deposition flow velocity of sediment. They can determine the design high water level at the entrance floor comprehensively in accordance with the classification of the pumping station on the premise that it is not lower than the flood control level of the port. They can also obtain wave height by referring to the top elevation of vertical breakwaters rarely subject to overtopping.

Abstract:The coal loading design capacity of the coal port area of Huanghua Port is 178 million tons，and the wharf carrying capacity has been maintained at about 200 million tons in recent years. The capacity of the port and shipping system is very tight. It is urgent to study the factors affecting and restricting the capacity of the port and shipping system，and put forward measures to improve the capacity of the port and shipping system. To reasonably determine the capacity of the port and shipping system，this paper makes statistics，sorting and analysis on the actual operation data of the wharf and channel in the coal port area，studies the rules of ships entering and leaving the port，and rechecks the calculation by using the methods of theoretical calculation and computer simulation analysis. The results show that the capacity of the port and shipping system of the coal port area is mainly affected by the wharf，channel and their coupling and matching relationship. Under the current wharf and channel conditions，the capacity of the port area can be improved to a certain extent by improving the loading efficiency of berths，increasing berths to be berthed and optimizing ship scheduling，but the improvement degree is limited，which cannot fundamentally solve the problem of insufficient capacity of the port area. Increasing loading berths in coal port area is the fundamental way to improve the capacity of the port area.

Abstract:Because of its own advantages，rubber tyred gantry crane（RTG）is widely used，and is an important yard equipment selection scheme for automated container terminals. The system research on the RTG scheme under the yard automation，as well as the full automation scheme cooperating with unmanned truck is very necessary in the future. The configuration and selection of automation system scheme is an important research content. Combining with an actual project，we sort out and study the automation system scheme of RTG and related auxiliary functions，and adopt the theoretical design and practical construction method to improve the implementation plan. The results show that the final implementation plan meets the requirements of automation capacity and efficiency，and takes into account the short-term and long-term automation levels.

Abstract:In Pakistan，the industrial power supply is insufficient，and large container ports use diesel gensets as their main power source. However，the conventional medium-speed diesel gensets fail to withstand a large suddenly applied load and have low efficiency. To solve this problem，this paper designs diesel gensets with flywheel energy storage，and completes the performance tests. The results show that the proposed diesel gensets can withstand a large suddenly applied load by itself. During its grid-connected operation with a conventional genset，the proposed diesel genset can also improve the work efficiency of the conventional diesel genset. Moreover，the conventional diesel genset can bear a more significant portion of the suddenly applied load，which is not exactly proportional allocation as in the theoretical analysis.

Abstract:Frequent damage to the top seal of the reversed tainter valve of the high water head ship lock has become the main problem affecting the operation reliability of the lock，and it is necessary to study the hydrodynamic characteristics of the top seal working state. The top seal 1:1 section test device is used for the top seal gap jet hydrodynamic test in the small opening of the reversed tainter valve. The development of gap jet cavitation，the hydrodynamic load distribution on the seal surface and the plusation pressure energy distribution rules are revealed. The results show that gap jet cavitation produces high frequency pressure pulsation of about 20 to 80 Hz on the lower surface of the top seal，which is easy to cause instability of the large deformed flexible seal，and is the cause of shock vibration in the initial stage of valve opening.

Abstract:To measure the operational risks of the mechanisms of vertical ship lift systems，this study focuses on the coupling among those mechanisms and the fuzziness of the operational risks and builds a fuzzy measurement model for those operational risks by integrating the decision-making trial and evaluation laboratory（DEMATEL）method with the fuzzy theory. It analyzes the coupling of the operational risks of a vertical ship lift with the risk factors from the perspective of the different operating conditions of the vertical ship lift. Then，it builds an index weighting model based on the DEMATEL method，develops a fuzzy measurement method for the operational risks of the mechanisms of the vertical ship lift system，and analyzes the Three Gorges’ vertical ship lift as an example. The results show that the operational risk level of the mechanisms of this vertical ship lift system is level IV，representing low risks. However，attention still needs to be paid to conditions that cause the unstable operation of the vertical ship lift. Such conditions include that water leaks in the gap between the ship chamber and the lock head，the ship chamber door cannot be opened and closed normally，the anti-collision device cannot be raised and lowered properly，the gap water cannot be filled and discharged as it should be，and the lock head door cannot be opened and closed correctly. Special attention should be given to the influence of the water surface fluctuation in the ship chamber on the operational safety of the vertical ship lift.

Abstract:The water and sediment conditions in the river section of the bridge area are complex，and the choice of bridge pier layout and bridge span affects the evolution of the main navigation channel，navigation conditions，and the total investment in the project. This study employs numerical simulation technology to deeply analyze the water flow conditions in the bridge area before and after the construction of the bridge and determine an economical and reasonable bridge pier layout and bridge span. The analysis comes down to the following two observations：1）The bridge pier layout should suit the changes in the riverbed and the channel as much as possible，thereby preventing the formation of a river section obstructing or restricting navigation. 2）The clear width of the bridge span should meet the requirements of navigation clear width and traffic capacity.

Abstract:In order to explore the characteristics of flow around the spur dike in Jiepai reach and clarify the relationship between the flow characteristics and the damaged dike head，this paper，under clear water and fixed bed conditions，uses the normal model to study the characteristics of flow around the spur dike in Jiepai reach of the Yangtze River and analyzes the influence of flow conditions on distributions of areas with the maximum velocity and maximum turbulence intensity from measured sections around the spur dike in Jiepai reach，especially the three-dimensional velocity data measured around dike head. The results show that the middle and lower parts of the dike are vulnerable areas from perspectives of velocity and turbulence intensity in x and z directions. As the velocity in the dike head increases，the submerged flow，dike head vortex system，and unit discharge are the main factors damaging the dike head.

Abstract:Regulation of the Danxikou rapids is a key project for the regulation of the Qujiang channel. The rising water level of Caojie Hydropower Station after impoundment and flood scouring lead to the development of the left branch of the river island and the collapse of the bank slope，consequently seriously endangering the stability of the navigation channel along the right bank and the property safety of residents on the left bank. This paper proposes building a revetment，enclosing the branch，flipping，and consolidating the beach as regulation measures and puts forward four regulation layout schemes. It calculates the multi-level flow of each regulation layout scheme with a two-dimensional numerical flow model and the maximum scouring depth formula. Then，it provides an optimal recommended regulation scheme through a comprehensive comparison according to the indexes of flow velocity，flow direction，and scouring depth. Specifically，the straight slope revetment prevents the continuous collapse of the left bank of Danxikou，the closure dam prevents the left branch from further deepening and widening，and the fish mouth revetment set at the head of the river island reduces scouring. The research results can provide a scientific basis for the design of the channel regulation project for the Danxikou section of the Qujiang River.

Abstract:The increase in ship tonnage and the development of large-scale port operation areas need to upgrade the level of the waterway from Jiulongpo to Chaotianmen in the upper reaches of the Yangtze River. In order to meet this demand，the Jiulongtan waterway regulation plan is studied through physical model tests，so that the waterway size of this section is upgraded from level III（2.7 m×50 m×560 m，water depth×navigation width×bending radius）to level I（3.5 m× 150 m×1 000 m）.Through analyzing the effects of the project implementation，it is concluded that：1）After the regulation of the Jiulongtan beach section，the scale of the channel meets the design requirements，the channel conditions are close to the general channel，and the navigation width is sufficient to allow the ship to operate normally. 2）The situation of bending，narrowness and rapid water flow in the beach section of Jiulongtan is completely solved，and the water flow is improved from the previous swirling water to the current steady flow state. 3）The ship is significantly easier to control，and it is safer to go through bends.

Abstract:The basic characteristics of initial wave and the determination method of the first wave height of landslide surges under current condition are studied by means of the 3D model test system of wave induced by granular rock landslide in curved shallow water area. According to the observation data of physical model test，we calculate statistically the maximum wave height，maximum period，effective wave height，effective period and wave steepness characteristic values of initial surge，analyze the effects of landslide angle，landslide volume，river depth and current velocity on the height of the first wave，and give the calculation formula of head wave height by using dimensionless and multiple regression analysis. Using the measured data of surge wave in Xintan landslide of the Yangtze River，we compare the formulas given in this paper with Noda formula，Slingerland formula，Pan Jiazheng formula，Yin Kunlong formula and formula of China Institute of Water Resources and Hydropower Research，and come to the conclusion that the difference between the calculated and measured values in this paper is the least.

Abstract:Large lagoon port areas are often connected to seas through narrow but long canal channels，and canals are confronted with multiple influences brought by offshore waves，ebb and flow of tides，and ship navigation. The significant wave-current coupling effect and the erosion caused by the ship propeller jet put forward high requirements for the bottom protection of canal bank slopes. In order to solve the bottom protection problem under this kind of complex hydraulic environment，this paper studies relevant calculation theories in the international standards and proposes a suitable calculation method，which can help engineers make better use of international standards to solve related issues. At the same time，the paper can provide a reference for revising Chinese norms and help them to be in line with international standards.

Abstract:Based on the evaluation index system for ecological remediation of the Yangtze River shoreline in Jiangsu Province，the calculation methods of various influencing factors in the soil water impact index（SWII）are further refined. The analytic hierarchy process（AHP）is used to calculate the weight of each factor in the SWII. Similarly，the weight of each parameter in the evaluation index system is also calculated by the AHP. The calculation method of ecological index（EI）is supplemented，and the corresponding ecological effect levels of different EI values are determined. The suggestions on the time node of evaluation are proposed to form a set of evaluation system that can be used for ecological remediation evaluation of the Yangtze River shoreline in Jiangsu Province. To investigate the application of the evaluation index system，a case study in shoreline of Wushan section，Nantong City，Jiangsu Province is carried out. The results show that：1）From 2018 to 2020，the values of EI calculated by the evaluation index system have increased year by year，and the maximum growth rate of ecological index is 90.09%. 2）The ecological effect changes from poor to excellent. 3）The evaluation index system is applied to the shoreline for ecological remediation，and the obtained ecological evaluation is consistent with the real project progress and ecological changes of the shoreline，which verifies the scientificity and applicability of the evaluation index system for ecological remediation of the Yangtze River shoreline in Jiangsu Province. It is recommended to be used in the ecological remediation evaluation of other shorelines in Jiangsu Province.

Abstract:After the Three Gorges became a reservoir，the river section from the Wujiang River Estuary to Baitao at Fuling became a perennial reservoir area at the tail of the Three Gorges reservoir，and the navigation conditions were greatly improved. The increase of the large vessels beyond the channel standard entering the Wujaing River highlighted the navigation risks.，Wujiang River beyond the channel standard is increasing，Wujiang River highlighted the navigation safety hazards. This paper probes into the navigation conditions for large ships with a length of 130 m when the water level of Qingxichang is over 160 m. The research results show that when the water level of Qingxi chang is 160 ~ 175 m and the flow from Wulong of Wujiang River is less than 2 000 m3/s，the navigation depth，width and bending radius of the research channel meet the navigation scale of large ships，but Sanmenzi，Longchuantuo，Xiaoxikou and Xinbengzi are restricted channels，Chongqing-Huaihua railway bridge and Sanmenzi are the river sections where boat meeting is prohibited，and the buildings across the river meet the dimension of navigation clearance of large ships. The navigation safety guarantee measures such as adjusting navigation aids，setting anti-collision facilities and safety warning signs in the bridge are put forward.

Abstract:Compared with previous years，the duration of high water-level and large flow was longer in 2020. At the same time，the channel became shallower due to sediment deposition in flood season，which causes unsafe factors for the normal operation of the channel. On this basis，we analyze the impact of catastrophic flood and the possible causes and countermeasures of channel deterioration. The results show that sediment deposits in the riverbed during the flood season is scoured during the dry season，and channel conditions depend on flood season deposition versus post-flood scouring. The long duration of the 2020 flood and the relative lack of time to recede after the flood results in the inadequate scour and navigation-obstruction in the upper shallow area，therefore emergency dredging is required to maintain the waterway conditions. We suggest to pay more attention to the channel changes and water conditions in this region in the next few years to formulate corresponding channel maintenance measures in time.

Abstract:The track beam supported by pile foundation is a continuous beam structure with elastic support. It is found that the larger the track beam size is，the safer the structure is. When the load and foundation parameters are similar，the track beam size and pile foundation layout adopted by different engineers are also quite different. Aiming at this problem，this paper analyzes the internal force of track beam from three aspects，i.e. vertical compressive stiffness of pile foundation，pile distance and stiffness of track beam. The results show that when the load and pile foundation layout are determined，there is an optimal beam height to minimize the amount of reinforcement in the track beam. Further analysis shows that when the load and beam length are certain，the internal force distribution of track beam is only related to the relative stiffness of pile and beam. When designing pile foundation to support track beam，it is necessary to try to calculate the optimal relative stiffness，which can make the internal force distribution more reasonable and save the project cost. Moreover，the optimal relative stiffness interval under different pile distances is given，which can provide reference for the design of similar projects.

Abstract:For the problems of existing container yard rail foundation design method in soft soil area including large differential settlement，high cost and long construction period，we introduce the collaborative design concept，which regards the handling equipment，rail and foundation as a system. Through improving the adaptability of equipment to tolerance and adding the facilities for settlement adjustment，we can extend the system’s range of adaptation to settlement，and thus achieve the goal of eliminating the pile foundation. Taking a container yard project as an example，we study crucial factors including settlement prediction，adaptability of equipment to tolerances，technique of rail adjustment，as well as the adaptability of foundation to settlement. It is concluded that the collaborative design method can adapt to larger post-construction settlement and achieve better economic benefits，thus it is worthy of popularizing.

Abstract:During the stability analysis of the deeply covered karst pile foundations，designers find it difficult to choose a suitable calculation method due to the large differences in the results of the different methods recommended by different specifications. Considering the deep cover characteristics of the karst in the site，this paper used the finite-element numerical simulation in Madis GTS to calculate the deformation of the karst cave roof and analyzed the impact of pile foundation loading on the karst cave roof. After a comparison with the theoretical calculation results，this paper proposed a parameter value standard for theoretical calculation formulas and a minimum safe thickness theory for deeply covered karst roofs. This paper provides an accurate and reliable basis for pile foundation design.

Abstract:In view of the problems including seepage deformation，seismic liquefaction，groundwater control，natural building material balance，and hydrophilic safety in the water environment of Yangwa ship lock of China’s North Canal，this paper uses comprehensive geological mapping，comprehensive engineering geophysical prospecting，geological drilling，in-situ test，hydrogeological test，laboratory test，water environment quality survey，BIM，and other technologies to investigate the construction site and conducts in-depth research on main engineering geological problems. The results show that the standard penetration and static cone penetration determine the lower limit of seismic liquefaction in the site，and the laboratory test of undisturbed sand obtains the physical and mechanical properties and seepage deformation parameters of the foundation bearing stratum. The field pumping test reveals hydrogeological parameters of groundwater control in the ship lock foundation pit. BIM finely calculates the amount of excavated spoil. The comprehensive analysis of water quality confirms that the water will pose no health risks to humans，and the investigation yields favorable results.

Abstract:To analyze，predict and control the influence of underwater blasting vibration on adjacent buildings in Xijiang Longwei waterway regulation project，we installed the blasting vibration detector to detect the peak velocity of particle vibration produced by underwater blasting. Comparing the detection data with those obtained by two different blasting vibration velocity prediction models by Newton iteration regression analysis，we obtain the blasting vibration propagation law of the underwater blasting engineering，and compare the vibration reduction effects of different technical schemes. The results show that in the underwater blasting engineering，the applicability of the traditional blasting vibration prediction mathematical model without considering elevation is low，and the applicability of the new prediction model considering elevation influence factors is high. And the mathematical model obtained by nonlinear regression using Newton iterative method can accurately reflect the blasting vibration propagation law of the project. The application of hole by hole blasting technology can greatly control the harmful effect of blasting vibration and protect the surrounding buildings.

Abstract:In the dock expansion construction on an island，the cofferdam provides a dry working environment for dock construction. Cofferdam construction is a key link in dock expansion construction and determines its success or failure. Taking into account engineering practice and local conditions，this study optimizes the form of the temporary cofferdam structure for dock expansion under the complex hydrogeological conditions on the island. After developing a new type of composite cofferdam structure，this study verifies that it meets stability and impermeability requirements through finite-element modeling and checking and that it offers a favorable dry working environment for dock expansion construction. Practice proves that the proposed cofferdam construction technology for dock expansion achieves remarkable results.

Abstract:The dredging pipe is an important part of medium transportation in dredging engineering，and its friction resistance is one of the decisive factors for dredging distance and performance. Based on Sanjiasha south channel project with the fine silt soil，we carry out the field test and comparative analysis of the transportation resistance under different pipe combinations with 2m-rubber pipe and 12m-steel pipe for the dredging pipe. The results show that the pressure loss increases with the increase of transport velocity and concentration；The friction resistance of the steel pipe combination is the smallest，followed by the “4 steel pipe + 1 rubber pipe” combination，and the “1 steel pipe + 1 rubber pipe” combination has the largest friction resistance，which increases by about 6% compared with the steel pipe combination. The research result provides a guidance for the layout of dredging pipes on the project site.