Abstract:Regarding the technical problems of high-water content，high compressibility，long dehydration time and insufficient supply of slime field in environmental dredging sediment，we study the electrochemical dehydration drying technology. The field area is divided into four units，namely the unidirectional vacuum，the unidirectional electrochemical，the double direction vacuum and the double direction vacuum electrochemical units，and the parallel comparison test is carried out. The results show that the dehydration effect of the electrochemical unit is more obvious than that of the vacuum preloading unit. Considering the power consumption and dehydration effect，the medium voltage（30 V to 60 V）is the optimal applied voltage value. In addition，the bidirectional drainage structure plays a good role in strengthening the electrochemical dehydration drying technology，which can realize the ectopic and efficient dehydration of multiple batches at fixed sites，and has certain engineering promotion significance for the urban areas with limited land resources.

Abstract:Regarding the large amount of dredged sediment produced by Baiyangdian dredging project，we study the resource utilization of greening planting soil prepared by improved dredged sediment. We design three auxiliary material schemes and use membrane covered aerobic fermentation to analyze the changes of physical and chemical indexes of sediment during the test according to the standard of CJ/T340—2016 greening planting soil. The results show that the contents of organic matter and nutrient elements of auxiliary materials directly affect the fermentation effect of sediment. The mixed fermentation effect of farmland waste as the main auxiliary material and sediment is the best. The soil infiltration rate，rapidly available nitrogen，available phosphorus and rapidly available potassium of sediment increase by 44.3%，18.0%，22.8% and 10.0% respectively，which is conducive to the improvement effect of river and lake sediment. This study provides scientific and technological support for large-scale resource disposal of dredged sediment，and realizes the closure of environmental protection dredging industry chain.

Abstract:To explore the effect of ecological dredging coupled with ecological restoration technology on the restoration of polluted water，water quality indexes named total phosphorus，total nitrogen and chemical oxygen demand are selected as the research objects. Relying on the Baiyangdian endogenous pollution control pilot project，three working conditions are set for the target fish ponds：in situ management area，original retention area and ecological desilting coupled ecological restoration area. Through continuous sampling and detection，the variation rules of water quality under different working conditions are obtained. The results show as follows：1）The use of ecological dredging and in-situ restoration measures can promote the total phosphorus，total nitrogen，and chemical oxygen demand of the water to increase to the surface water Class V water standard，but the water quality is difficult to reach Class III water standard；2）Compared with only a single in-situ restoration technology，the ecological dredging coupled with ecological restoration technology has more advantages. After a certain period of time，the total phosphorus，total nitrogen and chemical oxygen demand indicators of the water will reach the surface water Class III.

Abstract:Regarding the river management project，the defects and disadvantages of the traditional hard slope protection are analyzed，the advantages and characteristics of the plant-based ecological slope protection are expounded，and the mechanism of the plant-based ecological slope protection is discussed. Combined with the experience of domestic river control engineering，several common plant-based ecological slope protection technologies are systematically analyzed，and the technological characteristics and applicability of each technology are proposed. Relying on specific examples of river management projects，the advantages and disadvantages of different processes of plant-based ecological slope protection technology are evaluated from the perspectives of project cost，scour resistance，integrity，terrain adaptability，and applicable characteristics. The results show that：1）The plant-based ecological slope protection is a complete ecosystem，which is composed of water-soil-plant interaction. 2）Its effect mechanism includes hydrological effect and mechanical effect.3）At present，the plant-type ecological slope protection technology is widely used in the river regulation engineering in China，and its application range and application characteristics are different.4）For the river regulation and ecological restoration of a secondary tributary in the Songhuajiang river basin，the hollow hexagonal plant-type ecological slope protection and the gabion stone plant-type ecological slope protection materials are adopted，which have strong applicability and popularization.

Abstract:The multi-beam bathymetry system can obtain fine and comprehensive data on underwater topography. Nevertheless，such data are complicated and time-consuming to process，and the differences in data quality caused by different processing levels cannot be ignored，which necessitates the use of the filtering tools in the software to assist with multibeam data processing. To address the problems of complicated and difficult filtering theory and different filtering methods and effects，this paper analyzes the effect of filtering tools in dredging surveys by combining the commonly used filtering tools in the QINSY software and the Yidiantong software with engineering practice. Furthermore，the paper determines the filter selection for corresponding dredging projects. In this way，the paper shortens the multi-beam data processing cycle and reduces the probability of large differences caused by manual data processing.

Abstract:Since November，due to the influence of weather and temperature，the strength of prefabricated hollow slabs of the wharf upgrading project of Yueyang Changling Refining and Chemical Port Department rise slowly，and cracks appear in some prefabricated hollow slab，which seriously affect the construction period and the component quality.Aiming at these problems，this paper studies the method of improving prefabricated strength rising rate in the process of construction and the component quality，and carries out means of steam curing technology contrast experiment respectively. The results show that the steam curing technology can effectively improve prefabricated in the rate of strength rise in the process of production and reduce the components of the occurrence of cracks.The steam curing technology can improve the rate of strength rise and the quality of components，and reduce the waste loss percentage in the production process of similar prefabricated components，so as to effectively save the construction period and reduce the cost.

Abstract:Aiming at the calculation problem of the design wave elements of an artificial island in Panjin，the MIKE21 large-scale wave mathematical model is used to simulate the wave field in the nearby sea area before the project is implemented under the current topography，and the seepage wave elements in the return period and design wave elements of the water area near the project are calculated. The results show that：1）When the offshore waves propagate to the engineering area，the engineering position is mainly affected by the SW and SSW direction waves.2）The wave height changes relatively large within the -10 m isobath，and the wave height attenuates about 50% when it propagates to the engineering area . 3）The east and west sides of the project area are shoal areas. The waves are broken and the wave height attenuates significantly. 4）The waves mainly enter the front of the engineering revetment along the deep groove，and the SSW wave height is slightly larger than the SW wave height.

Abstract:Regarding the problems such as poor construction adaptability of the large cutter suction dredgers developed in China under medium and long-term wave sea conditions，and limited row spacing in long row spacing projects. In this study，taking the “Tianshan” ship as a research object，through the theoretical analysis，numerical simulation，finite element analysis and calculation，real ship verification and other methods，we upgrade a series of the performance improvement，including the positioning system，the conveying system，and the power system.The technologies for large cutter suction dredgers，which has been successfully applied. It provides a reference for the performance improvement and transformation of the large cutter suction dredger developed at the early stage in China.

Abstract:Aiming at the problems of backward basic theoretical research of dredging technology and inaccurate numerical simulation of cutterhead excavating clay in China，through the methods of theoretical research and small-scale trial production，the target experimental clay is prepared，and a model clay cutterhead suitable for laboratory use is developed. On this basis，the laboratory experimental research of model cutterhead excavating clay was carried out，and the influence of the process parameters such as the rotating speed of cutterhead，traverse speed，mud layer thickness and forward displacement distance on the mud concentration of excavation test was analyzed . The principle is selecting the medium cutter speed，appropriately reducing the traverse speed，and giving priority to the method of increasing forward displacement distance to improve the excavation section area under the condition of ensuring that the front end of the bridge does not hinder the yaw. The research results can provide a reference for the selection of clay excavation process parameters.

Abstract:Regarding the problem that the internal flow field of the draghead of the rake suction dredger is not clear when excavating clay，the flow field in the drag cavity is simulated，analyzed and optimized. The change of total pressure difference，static pressure difference and cross section velocity of the new and old dragheads are analyzed by using Computational Fluid Dynamics（CFD）value simulation calculation technique. The results show that the vortex area in the drag cavity is reduced，the energy loss is reduced，and the flow performance of clean water is improved. The conclusions are that the streamlined internal cavity of the new draghead makes the internal flow smooth，the transport resistance is reduced，and the cross section velocity tends to be reasonable. Its performance is better than the old draghead.

Abstract:Hydraulic reclamation construction involves theoretical knowledge of hydraulic pipeline transport，including that of the combined system composed of pumps，mud pumps，and pipelines，and the subsystems are interrelated and relatively complex. Consequently，the dredging management personnel find it difficult to obtain a proper understanding and analyze problems encountered in the process of hydraulic transport inaccurately. Regarding the above problems，this paper adopts energy conservation analysis to analyze the principle of hydraulic pipeline transport，derive empirical formulas，and analyze examples. Dredging management personnel can thereby deepen their understanding of the principle and formulas，predict the production capacity of hydraulic reclamation more accurately，analyze and solve technical problems in construction，achieve fine management，and avoid relevant risks.

Abstract:Relying on the east channel expansion project of Qinzhou Port in Guangxi，this paper investigates the problems，such as difficult excavation，serious wear of cutter teeth and pipes，and easy blockage of pipes during transportation，encountered in the dredging of typical sandstone by the heavy-duty cutter suction dredger “Tiankun” and analyzes the property indexes of dredged sandstone. From the perspective of the correlation of the excavation specific energy of weathered sandstone with the ship construction parameters，the paper derives the calculation formulas for the property indexes，such as saturated uniaxial compressive strength，power consumption of the reamer，and excavation production，of the sandstone in Qinzhou according to excavation construction parameters and the theory of specific energy. These formulas can be used to forecast excavation production during the excavation of weathered rock by a heavy-duty cutter suction dredger and provide technical support for the operation and production of dredging projects.

Abstract:The boundary conditions for the environmental dredging of urban braided rivers are complex due to poor water quality，complex flow patterns，serious siltation，and large numbers of river-crossing buildings. This paper proposes a concept that the design of the environmental dredging depth should unfold from the perspectives of pollution layer depth，riverbed evolution，and structure safety，and the concept involves the following three aspects：1）Controlling the dredging depth with the bankfull elevation is advisable at the compound section of a single river section. 2）for the stabilization of the riverbed，the design of the dredging depth presupposes controlling the proportion of the cross-sectional area and keeping the main channel consistent with the natural slope. 3）At dikes and structures，the design of the dredging depth should consider the influences of the safety distance from the dikes and structures and the scouring depth after dredging to excavate the polluted sediment to the maximum extent on the premise of stable riverbeds and safe structures. The proposed concept has achieved successful application to an environmental dredging project in a river section.

Abstract:Comprehensive watershed management is of great significance for wetland water environment improvement and ecological restoration，and hydrodynamic numerical simulation is an important means to predict the restoration effect. Based on the lake morphology，hydrological conditions，landform characteristics and watershed management project of Futou Lake，this paper analyzes the water quality of Futou Lake by Mike 3，establishes the flow field of the lake and carries out the hydrodynamic simulation，compares and analyzes the hydrodynamic characteristics and changes before and after the removal of polders，estimates the impact of the removal of polders on the flow field of the lake，verifies the rationality of the process，and provides reference for the analysis of water quality changes of the whole lake. The effective application of numerical simulation in watershed management and ecological restoration project can optimize the lake ecological restoration scheme as a whole.

Abstract:Dredger is the most widely used dredging equipment in dredging engineering，and its productivity directly affects the efficiency of the dredging process. This paper establishes a prediction model of dredger productivity by using rough sets theory，and the model validation experiment is carried out for the working condition of cutter suction dredger excavating cohesive soil. According to the real ship data and empirical research results，soil parameters and soil grade are used to characterize the soil change，and the productivity prediction results under the two methods are compared. The results show that the productivity errors of the both methods are less than 10%，and the method of establishing productivity prediction model using rough set technology is feasible. The predicted value is calculated based on soil grade is much closer to the actual value.

Abstract:Mixed soil exists in hydraulic reclamation project. Regarding the problem of large settlement of sludge in foundation treatment，this paper studies the relationship between the settlement velocity，flow diameter and outlet of hydraulic reclamation soil particles with critical particle size，The theoretical settlement velocity of critical particle value is obtained by using Stokes law. The width of the outlet for discharging critical soil particles is set by combining the flow diameter，outlet velocity and particle settlement velocity. Taking the thin-walled weir as an example，other weirs can be calculated by the corresponding flow formula. Through the analysis and calculation of critical conditions，the contradiction between hydraulic reclamation construction and foundation treatment is solved，and reasonable thin-walled weir parameters for loss control are sought to provide reference for practical engineering applications.

Abstract:In practical engineering，different dredging soil quality and various soil quality that affect dredging efficiency will be encountered. The solution of dredging engineering-related problems cannot be separated from the study of the original rock and soil characteristics. The remolding of all kinds of dredging soil technology at home and abroad for rare precedent，hindered the research of dredging engineering issues. This article carries on the technology research of remodeling compacted clay and the properties analysis of compacted clay. Impact compaction method is adopted to improve the compaction，geting a method which can fit natural characteristics well. The results reveal that：through the improvement of soil，the impact compaction method can realize the clay remolding with different plasticity index，compactness degree and standard penetration strike number. The influence trend of soil moisture content and liquid index on compactness and penetration strike number is obtained，which can provide a reference for clay remolding technology.

Abstract:Siltation at inbound channels becomes increasingly serious as the service life of the channels increases. Improving the irrigation and water supply capacity of the channels，meeting the needs of water quality，and enhancing the flood absorption and flood control capacity necessitate the timely desilting of the inbound channels. Dredged soil produced by the desilting of the inbound channels defies transportation and unloading by water as in river and sea areas. Instead，it requires transportation onto the shore for treatment，resulting in complicated and costly treatment process for dredged soil. Moreover，failure to meet the desilting requirements of the projects due to limited stacking area and environmental pollution is common，which further affects the normal promotion of channel desilting. To address the problem of the difficult treatment of dredged soil during the desilting of inbound channels，this paper adopts the resource utilization technology for dredged soil and optimizes the desilting process to achieve the purpose of normally promoting desilting construction. This process can not only promote the normal implementation of the desilting of inbound channels but also meet the requirements of rational utilization of resources. Therefore，it deserves extensive popularization in the desilting projects for inbound channels.

Abstract:Grab dredgers encounter various problems during dam removal construction in strong currents（current velocity of 3-4 m/s），such as difficult docking for barges，serious anchor dragging of grab dredgers，excavated rocks stuck in grab cracks，insufficient fullness of grabs，inability to grab overlarge block stones. To solve the above problems，this paper studies the anchor distribution of a grab dredger，the segmentation of the construction area，the grabbing process of the grab dredger，and the crushing of super-large block stones. By taking various measures，such as adding a traveling anchor to the grab dredger，adjusting the construction direction of the grab dredger and the construction segmentation，changing the grabbing direction of the grab，and cleaning the rock with the grab after it is crushed by the rock hammer of the grab dredger，this paper solves the problems of restricted anchoring，restricted barge docking and separation，serious anchor dragging，and difficult excavation during the construction of rock dam removal by a grab dredger. Moreover，the paper expands the adaptability of grab dredgers to project construction and increases the daily output of the grab dredger by more than 40%. It can provide a reference for similar hydraulic reclamation projects.

Abstract:As the soil in the hydraulic reclamation project of the Jiangsu Binhai Liquified Natural Gas（LNG）Project，clay has a high bulk density and is difficult to transport，ultimately imposing high requirements on the operation of ship officers. During the long-distance transport in the above project，pipe blockage and pipe explosions occur frequently. According to the working conditions of the project，this paper analyzes the data before and after pipe blockage and explores the change law of parameters by theoretical calculation and full-scale ship experiments. On this basis，the paper summarizes the causes of pipe blockage and pipe explosions and optimizes the pipe layout and the ship officers’ operation. This paper solves the problems of frequent pipe blockage and pipe explosions in clay transport with a long discharge distance and enhances the time utilization rate and productivity of ships.

Abstract:To solve the problems，including single molding and unstable structure，of the traditional revetment of the Beijing-Hangzhou Canal，this paper focuses on a channel regulation project on the Beijing-Hangzhou Canal and applies two new materials，i.e.，molding templates and split blocks，to the armor of the concrete gravity revetment. By investigating the application of the two types of revetment molding，this paper summarizes their main construction points and comparatively analyzes their exterior effects and economic benefits. The results show that the two types of revetment molding both display the molding effect well and share a mutually reinforcing relationship with the canal culture. Specifically，molding templates have a better appearance and higher cost per use. Nevertheless，it can be recycled and is thus more economical in the long term. In contrast，split blocks are more environmentally friendly and economical. The two new types of revetment molding both have broad promotion prospects in river regulation and human landscape design in cities along rivers.

Abstract:Regarding the issue of tide level control in the bathymetry of the long Panjin Channel，this paper studies the tidal theory and builds a tide level calculation model by a tide level calculation technology based on tidal harmonic analysis according to the specific situation of the Panjin Channel to control the tide level of the long distance offshore channel. By comparing the measured data on the tide level at fixed points at sea with the calculated tide level data and the measured data on the underwater topography along the channel in different time periods，the paper finds that the data obtained by the two methods all meet the requirements of the relevant specifications. The results fully testify to the point that the tide level calculation technology based on tidal harmonic analysis is accurate and reliable，can meet the accuracy needs of bathymetry，and can thus be used in the bathymetry of long channels of the same type.

Abstract:To solve the problem that submerged breakwaters are highly likely to cause grounding and collision，this paper takes a breakwater project in Tianjin Port as the research object and optimizes the preliminary design of a revetment structure of single-layer accropode blocks into one of double-layer accropode blocks. By comparing the use functions，construction complexity，stability，and cost of different forms of armor structures of double-layer accropode blocks，this paper analyzes the feasibility of the proposed scheme and puts forward corresponding solutions to the actual problems encountered in the construction. The results show that the double-layer accropode blocks can solve the problems of grounding and collision and meet the requirements of the overall stability of the armor structure of the breakwater.

Abstract:The engineering quality control of mass concrete structure is difficult. During the construction of Sanya Phoenix Island International Cruise Port phase II project，in order to ensure that the mass concrete structure quality meets the design requirements，before the formal construction of mass concrete，the production，pouring and curing of mass concrete test blocks are carried out by simulating the on-site working conditions，and the internal temperature and strain change laws of mass concrete test blocks are monitored. The optimization of concrete mix proportion design is studied. A better concrete mix proportion is obtained through two groups of comparative tests of different concrete mix proportions（water binder ratios are 0.38 and 0.40 respectively）under the same conditions. The results show that the maximum temperature，maximum temperature rise，internal and external temperature difference and maximum cooling rate of concrete block with water binder ratio of 0.38 are higher than those of concrete block with water binder ratio of 0.40. It is recommended to select water binder ratio of 0.40 for mass concrete construction in high temperature areas.

Abstract:In recent years，the practice of the Yangtze River channel regulation project has proved that permeable frames can well promote siltation and have thus gradually become an indispensable engineering component in this channel regulation project. The 6-meter-deep channel regulation project in the Wuhan to Anqing section of the Yangtze River trunk line has an intensive demand for frame prefabrication. Moreover，the prefabrication progress of permeable frames is far behind schedule due to the abnormal drop in water level at the end of 2019 and COVID-19 at the beginning of 2020. For the above reasons，this paper replaces the integral molds with assembled molds for prefabrication and conducts a comparative analysis from three aspects，namely，the finished product quality of prefabricated components，the demolding time of components，and the construction cost. It further presents a permeable frame prefabrication process with high quality，low cost，and high efficiency. In this way，the paper also shortens the construction period of subsequent throwing operations on water and minimizes the impact of the construction period on the environment.

Abstract:The early high-pile wharf structure is damaged due to corrosion，aging，overload，fatigue and other reasons，which affect the function of the wharf. Regarding these problems，the reinforcement of wharf components is studied. Combined with the reinforcement example of high-pile wharf，ｂｙ the field test and numerical simulation method，the reinforcement effects of carbon fibers cloth on damaged components are analyzeｄ through the deflection and stress change of concrete components before and after reinforcement. The results show that sticking carbon fiber cloth can effectively reduce the deflection and stress of concrete components，and has a good reinforcement effect on damaged components，which can provide a reference for the repair of similar wharfs.The results show that CFRP can effectively reduce the deflection and stress of concrete members，and has a good reinforcement effect on damaged members.

Abstract:By investigating an actual ship lock project，this paper focuses on the quality control of concrete structures，formwork erection，and concrete warehousing methods to solve the problems of the high lock chamber wall，difficult formwork erection，and difficult concrete warehousing. By adopting the methods of layered pouring of concrete wall structures，formwork erection by a formwork support frame with a mobile frame body，and concrete warehousing through the bogie pipe，the paper improves the engineering quality of concrete structures，shortens the construction period，reduces the cost，and promotes the engineering benefit on the premise of safe，reliable，and rapid construction. This paper can provide a reference for the construction and quality control of high concrete wall structures.

Abstract:According to the requirements of offshore piling construction during the construction positioning of offshore piling barge and the reconstruction and expansion of old wharf under complex working conditions，a set of auxiliary positioning system with the functions of accurate navigation of piling barge，real-time three-dimensional display of all elements in the construction positioning process，anti-collision pre alarm of pile body and completion data output is developed. This paper expounds from the aspects of demand analysis，function design，core algorithm，code level implementation and practical application. Through pre-construction control，auxiliary positioning and completion data retention，the system accurately evaluates the construction safety，which can realize all-round accurate control of the positioning process of the entire offshore piling construction and meet the safety and quality control needs of the construction personnel.

Abstract:Taking the construction of a liquid chemical terminal in northern China as an example project，this paper builds a three-dimensional information model for the terminal project and supporting facilities according to the design drawings. Through the application of building information modeling（BIM）technologies to collision inspection of structural components，simulation of liquid loading and unloading operation areas，and visual process and technical disclosure，the paper effectively solves various problems in the design and construction process，such as the low efficiency of technical disclosure，the conflict between the installation positions of pipes and steel frames，the collision of pile shafts with pile group foundations，and the conflicts among liquid loading and unloading operation areas. The application of BIM technologies reduces communication costs and provides a technical means for fine project management. It solves the collision problem at the design stage to reduce the risk of rework during construction. This paper serves as an exploration of technical routes and solutions for the application of BIM at liquid chemical terminals.

Abstract:When the irregular slope surface of a riprap seawall lies below the sludge surface of a seawall-side hydraulic reclamation area，the following problems deserve further discussion：1）The conventional process of vacuum preloading combined with surcharge preloading featuring drainage plate installation fails to achieve a vacuum effect due to connection with the open sea by the gaps among seawall stones. 2）Surcharge loading directly from the seawall side is highly likely to cause the sliding of the mud surface to the inside. This paper focuses on the film-pressing process of the film-pressing ditch，surcharge loading methods，and drainage plate equipment near the seawall. It solves the problems，namely，difficult maintenance of a vacuum effect and easy sliding of the mud surface，in vacuum preloading combined with surcharge preloading under the abovementioned conditions by translation of the film-pressing ditch，multi-point uniform surcharge loading，the addition of drilling steel at the end of the equipment，replacement in the shallow area，and continuous scheme optimization. The results show that the scheme adopted is safe，reliable，and convenient for construction，and it provides a reference for similar projects.

Abstract:Regarding the loads on the track beam of a gantry crane under eccentric loading，this paper investigates the loads on a track beam and foundation settlement and obtains the loads on the track beam and the settlement displacement of the foundation under eccentric loading by the elastic foundation beam method and a numerical analysis method. The conclusion is that the required areas for upper longitudinal reinforcement，lower longitudinal reinforcement，and stirrup when the track beam is under eccentric loading increase by 17.08%，56.83%，and 16.5%，respectively，compared with those in the case of axial loading. The ultimate design wheel load under the ultimate load-carrying capacity of the structure is 1 197.2 kN/m，which is 2.55 times the design wheel load of 250 kN/m. However，the deformation of the foundation under the design wheel load reaches 39.67 mm and is close to the value required by the specification，indicating that deformation control is a major factor in foundation design.