Abstract:Carbonaceous mudstone belongs to a special type of soft rock,which is widely distributed and has poor engineering properties,and has a significant impact on canal projects.Therefore,it is urgent to study the engineering characteristics and prevention mechanisms of carbonaceous mudstone.The Madao Hub of the Pinglu Canal is located on a carbonaceous mudstone foundation.During the investigation phase,methods such as drilling sampling,mineral analysis,in-situ shear tests,and laboratory compression tests are employed.During the construction phase,techniques including on-site observation,geological mapping,geological sketching,and safety monitoring are utilized to systematically reveal the engineering characteristics and prevention mechanisms of carbonaceous mudstone.The main research conclusion:the composition of carbonaceous mudstone is primarily clay minerals,with a carbonaceous content of 6% to 40%.The strength of carbonaceous mudstone is influenced by its burial depth,structural features and groundwater environment,leading to significant variability.Reliable data must be obtained through investigation methods such as sampling,in-situ testing,and laboratory experiments.Carbonaceous mudstone is prone to weathering and softening after excavation exposure,with softening resulting from a combination of internal and external factors.Internal factors include its clay mineral composition and hydrogeological properties,while external factors involve excavation unloading and wet-dry cycling.For carbonaceous mudstone foundations,a protective layer must be reserved,and strict foundation cleaning and acceptance procedures should be followed.If necessary,bearing capacity testing and foundation treatment should be conducted.For carbonaceous mudstone slopes,timely sealing should be performed after excavation and slope cutting,and appropriate reinforcement and drainage measures should be implemented based on their distribution and impact extent.

Abstract:The utilization of underwater mold bag concrete is prevalent in the construction of the Pinglu Canal project.The leakage of cement slurry will have serious impacts on the environment and ecology.Anti-fouling curtains are commonly used in engineering to block the diffusion of pollutants.However,there is relatively little research on the diffusion dynamics and effectiveness of such barriers.Therefore,this study employs Fluent software to establish a three-dimensional computation model to simulate the barrier effect of floating anti-fouling curtains on cement slurry pollutants,analyze the influence of different anti-fouling curtain arrangements and parameters on the anti-fouling effect,and determine the range of influence.The research results indicate that optimal pollutant control effect is achieved when the underwater inclination angle is 30°,the angle with the longitudinal section of the river is 20°,the distance between the anti fouling curtain and the pollution source is 2 m,and the underwater depth of the anti-fouling curtain is 4 m.The research can provide an optimized scheme for the specific layout of anti-fouling curtains in underwater mold bag construction,so as to achieve the best control of cement slurry pollution diffusion.

Abstract:In order to investigate the coupling effect of chloride ions and cracks on the corrosion of reinforcement in coral concrete,we employ electrochemical experiments to compare with the corrosion state changing law of reinforcement in coral concrete component with different exposure time in chloride environment and width of prefabricated cracks,and analyze the influence mechanism of chloride ions and cracks on the corrosion of reinforcement in coral concrete by X-ray diffraction (XRD) and scanning electron microscope (SEM) tests.The results show that the risk of reinforcement corrosion increases with prolonged exposure time and wider prefabricated cracks.A significant impact on steel reinforcement corrosion is observed only when the width of pre-existing cracks surpass a certain threshold value.Furthermore,an increase in the width of prefabricated cracks is led to a shift in corrosion products from predominantly magnetite to primarily akaganeite and hematite,and accompanied by a transformation in the microscopic morphology towards a rough and irregular appearance.

Abstract:Through long-term exposure test and engineering investigation,the long-term protective effect of surface coating on marine concrete structure is studied,and the influence of coating on service life of concrete structure is quantitatively evaluated.The research shows that the coating can effectively isolate chloride ion intrusion,significantly improve the service life of concrete structures,and the coating system using epoxy asphalt and chlorinated rubber surface layer has better anti-aging performance.However,due to the influence of the actual service structure by working load and complex painting construction environment,the chloride ion concentration in the engineering structure is significantly higher than that exposure test.In the actual service environment,the surface chloride ion concentration increases gradually with the extension of service time,and the surface chloride ion concentration conforms to the linear function model with service time(Cs=kt）.Considering the effect of coating on the time-varying characteristics of chloride ion concentration on concrete surface,a quantitative evaluation method for durability life of coated concrete structures is established.

Abstract:To further improve the wave dissipation performance of permeable breakwater,this paper proposes a stepped breakwater structure based on the plate breakwater,and explores its wave dissipation performance in regular waves.A two-dimensional numerical model is constructed by Fluent software to analyze the effects of different lower baffle lengths,diving depths and wave heights on the transmission coefficient,reflection coefficient and energy consumption coefficient of the stepped breakwater,and the changes of the flow field around the structure are analyzed.The research results show that the transmission coefficient of the stepped breakwater decreases with the increase of the relative lower baffle length,relative wave height and relative diving depth.The reflection coefficient increases with the increase of the length of the relative lower baffle,and decreases with the increase of the relative wave height and relative depth.The energy consumption coefficient increases with the increase of relative lower baffle length,relative wave height and relative diving depth.

Abstract:Determining the microstructure and mechanical properties of reinforcement corrosion products is crucial for understanding the concrete structure durability failure and developing the concrete corrosion-induced cracking model.The reinforcement corrosion products before and after concrete cracking are sampled and analyzed on the basis of a decommissioned bridge in Zhanjiang and an aging wharf in Wenzhou,both exposed to the real marine environment.The chemical composition,microstructure,and volume expansion coefficient of corrosion products are measured by X-ray diffraction (XRD),thermogravimetric analysis (TG),and scanning electron microscopy (SEM).The nanoindentation experiments are carried on to determine the elastic modulus and hardness of the corrosion products.The results indicate that the main components of the reinforcement corrosion products before and after concrete cracking are oxides of iron and oxyhydroxides.The volume expansion coefficients of the corrosion products in different zones,including the splash zone after cracking,the splash zone before cracking,the tidal zone before cracking,and the submerged zone before cracking,gradually decrease,with values of 2.552 2,2.341 4,2.340 5,and 1.990 3,respectively.Furthermore,the average elastic modulus of the reinforcement corrosion products before concrete cracking ranges from 137.06 to 154.70 GPa,while the average hardness ranges from 1.001 to 1.149 GPa.After concrete cracking,the average elastic modulus of corrosion product is 125.89 GPa,and the average hardness of corrosion product is 0.892 4 GPa.

Abstract:Based on four natural sandy beaches in Lianyungang muddy coast,this study analyzes the morphological characteristics of beach plane and profile,tidal current conditions,wave conditions and sediment movement characteristics to study the reasons for the existence of sandy beaches in muddy coast environment.The results show that the natural beaches are concave arc-shaped landforms with headlands at both ends,and the main direction of the incoming waves is consistent with the direction of the bay mouth,which is not conducive to significant coastal sediment transport and avoids sediment loss.The natural beach profile has obvious turning characteristics,and the larger front water depth is conducive to reducing loss during the propagation of offshore waves,which can maintain larger wave dynamic conditions in front of the beach.The large waves in the direction of the natural beach should reach a certain concentration and frequency,and the large waves of the beach with H1/10 wave height greater than 0.40 m accounting for more than 36.6% is conducive to better beach surface characteristics.Waves are the main driving force of the mud resuspension.The sand carrying capacity of the tidal current is greater than the background sand concentration,which is conducive to the formation of the beach,and the larger the sand carrying capacity,the wider the beach width.

Abstract:The air entraining agent mixed with concrete to prepare the air-entrained concrete is one of the important technical measures to improve and ensure the durability of concrete structure against freezing and thawing.T.C.Powers proposed the concept of spacing factor,the spacing factor of air-void system in hardened concrete is the most crucial.In our country,the determination of air-voids system parameter in hardened concrete technology by linear traverse method has been incorporated into some industry standards.For carrying out relevant test and inspection work reasonably and accurately,this paper selects the formula on the basis of the boundary value of 4.342 between the paste content in hardened concrete,and the volume percentage of air content when calculating the spacing factor,and puts forward improvement suggestions for the determination method to further standardize the determination technology of air-void system parameters in hardened concrete.

Abstract:Aiming at the mutual influence of dust emissions from coal piles in an open yard of coal terminal,by setting different wind angles and wind speeds,the study uses numerical simulation methods combined with the emission factor formula proposed by United States Environmental Protection Agency (EPA) to quantitatively analyze the dust emission characteristics of existing coal piles on adjacent piles at different locations in the yard.The dust intensity of different pile positions is then visualized.The results show that under wind angles of 0°,45°,and 90°,the maximum dust emission amounts are 2.08,3.70,and 2.60 kg,respectively.Under wind angles of 0° and 45°,the position with the lowest dust intensity is located at the downwind pile position.At a 90° wind angle,the shielding effect of the coal piles exhibits a symmetrical pattern.The research results can provide reference for spray operation.

Abstract:In order to reduce the cost of maintenance dredging and improve the navigational efficiency of ships,we take the fluid mud in the harbor area of Binhai Port in Yancheng as the research object,and conduct a study on the seaworthy density of fluid mud in Binhai Port on the basis of characteristics of fluid mud.We carry out the thickness distribution of fluid mud,sediment particle size analysis,and rheological characteristic test at shallow points along the wharf front after dredging in the harbor pool and channel area to study the characteristics of fluid mud,and then combine the relationship between the mucous content of fluid mud and the seaworthy density,the rheological characteristic test,and the theory of laminar-turbulent flow transition together to determine the seaworthy density of fluid mud in the harbor area of Binhai Port.The results show that the average thickness of fluid mud in the harbor area of Binhai Harbor is 1.71 m,and the sediments are mostly dominated by viscous fine particles,with median particle sizes ranging from 0.006 to 0.008 mm,and the content of viscous particles is more than 90%,which is in line with the condition of utilizing the seaworthy water depth.It is determined that the standard value of density of the seaworthy fluid mud in the harbor area of Binhai Port is from 1,200 to 1,240 kg/m3.

Abstract:In view of the anti-corrosion,sealing,and overall stiffness issues of the steel structure on the top of the silo in the third and fourth phases of coal port area in Huanghua Port during operation,a structural optimization study is conducted on the silo roof structure.Two structural schemes,a concrete cone shell silo roof and an improved steel structure silo roof are proposed.The advantages and disadvantages of the two schemes are compared and analyzed.Emphasis is placed on the stress analysis and construction scheme research of the concrete cone shell silo roof structure,and the largest diameter cone shell silo roof structure and the Bailey frame steel truss+central column support system in China are proposed.The overall stiffness,anti-corrosion measures,and external maintenance plate of the improved steel structure silo roof scheme are studied with emphasis.Heavy anti-corrosion measures and aluminum magnesium manganese plates are adopted to increase the anti-corrosion protection period of the steel structure to over 30 years.The results show that both schemes can effectively solve the existing problems.

Abstract:Given that liquefied natural gas (LNG) terminals require large quantities of seawater as a cold source during operation,the construction of water intake and drainage projects is particularly important.Water intake and drainage activities inevitably have an impact on the flow field of the adjacent water areas of the project.Therefore,it is necessary to conduct a systematic analysis of the tidal current field near the project.This study takes the Yingkou LNG terminal project as an example and utilizes the open-source hydrodynamic numerical model FVCOM to simulate and compare the hydrodynamic characteristics of the tidal current field within the port area before and after the implementation of the water intake and discharge project of Yingkou LNG terminal.The focus is on investigating the impact of water intake and drainage outlet construction on the nearby three-dimensional flow field.The simulation results indicate that after the project implementation,there are slight changes in the surface and bottom flow velocity amplitudes of the tidal field near the water intake and drainage outlet,but the maximum change in surface flow velocity does not exceed 0.05 m/s.By analyzing the surface cross-flow velocities at typical measurement points within the port area,it is found that the maximum difference in cross-flow velocity among the characteristic points does not exceed 0.016 m/s.In summary, the implementation of water intake and drainage engineering has a very limited impact on the hydrodynamic characteristics of the tidal field in the study area,especially on the overall distribution pattern of the tidal field,which has not undergone significant changes.The research results can provide reference for the design and evaluation of similar engineering in ports.

Abstract:As an important spatial carrier in the emergency rescue management system,the emergency rescue base is the foundation for carrying out rescue activities.Through a review of existing research both domestically and internationally,it has been found that there is a lack of research on the planning and design of emergency rescue bases for serving ports,and there is no mature methodology system in place.Based on the practical case of the project,by sorting out the types and risk characteristics of dangerous goods in ports,the special needs of emergency rescue in port areas are clarified,and planning and design methods for emergency rescue bases in dangerous goods port areas are proposed from the aspects of macro layout,land selection,functional structure,construction content,etc.The macro layout should be scientifically based on the number of target objects.The selection of land use site should be based on multiple factors such as higher-level planning,geographical environment,and limiting conditions.When designing the base,it is necessary to coordinate the interrelationships between various functional areas to improve usage efficiency.The determination of construction content should be based on the cargo and accident types in the port area.The research results can serve as a reference for the formulation of special plans and the planning and design of the construction of emergency rescue bases in the port area.

Abstract:The downstream water level of the navigation hub is often lower than the designed lowest navigable water level during the dry season because of the factors of released clear water，sand mining and waterway dredging,etc.It will lead to problems that the water depth of the lock threshold and the submerged water depth of the water conveyance culverts are both less than the designed values and the maximum water head exceeds the designed water head.In this case,the normal operation of the ship lock may be affected.In response to the problem of a certain constructed hub,systematic analyses are conducted on the characteristics of the downstream water level changes of the dam and the characteristics of ship types crossing the dam in the past two years.The ship sinking index and surplus depth during navigation are calculated when the downstream low water level is beyond the design standard.The hydraulic characteristics of the ship lock filling and emptying process are studied under the reduced initial water depth and the increased water head conditions by mathematical model.And the corresponding hydraulic conditions of the filling and emptying system,the valve working conditions and the ship berthing conditions in the lock chamber are analyzed.On this basis,the opening modes of the valves are put forward based on the changeable downstream water level,which can optimize the hydraulic characteristic index and improve the berthing conditions of ships in the lock chamber.In addition,the engineering improvement measures of the valve system and the ship draft control parameters are given under the small submergence depth situation，so as to reduce the impact of downstream water level drop and ensure the operation of the ship lock.

Abstract:The Matai Estuary Beach reach is located in the fluctuating backwater area of the Nuozhadu Reservoir on the Lancang River.Upstream,Hutiaoshi Beach is characterized as a narrow and shallow shoal,while downstream,the Matai Estuary Beach becomes a shallow and swift shoal at the stream mouth during the low-water level.Before the implementation of channel regulation works,the comprehensive criterion E value for the Matai Estuary Beach during high flow periods of the drawdown exceeded the permissible limit by 2-3 times,presenting significant challenges for navigation improvement.To address this issue,optimization trials are conducted for the downstream Matai Estuary Beach using a physical river model,aiming to meet the navigation improvement goals while minimizing upstream water level drops caused by the engineering works.The recommended plan involves dredging to increase the channel dimensions and expanding the discharge area at Matai Estuary Beach,accompanied by backwater measures through filling deep pools beneath the shoal.For the upstream Hujiaoshi Shoal,obstacle clearance is proposed to enhance channel dimensions.These measures have significantly improved the navigation conditions in the Matai Estuary Beach reach.However,under conditions of low water levels in front of the Nuozhadu Dam and high discharge from the Dachaoshan Dam,resistance to navigation at the Matai Estuary Beach remains considerable.The study further analyzes the impact of raising the operational water level in front of the dam on the navigation conditions of the recommended plan,and concludes that appropriately raising the water level in front of the dam could meet the requirements for ships to pass through the shoal.

Abstract:Taking the two-stage arrangement of double-lane ship locks in the section from Changshan River to the provincial boundary of the Zhejiang-Jiangxi Grand Canal as an example,this paper conducts research on the water-saving and intensive water use guarantee schemes for ship locks.For water-saving in ship locks,the method of mutual filling and emptying between double-lane ship locks is recommended.Through the analysis of water demand of the two-stage double-line ship locks,the theoretical water-saving rate can reach 50%.Considering the ecological water and shipping water demands of the canal,combined with factors such as the amount and distribution of water resources along the route,as well as topography and landforms,the water supply sources are studied and analyzed.Three water security schemes are proposed:constructing new reservoirs within the region,lifting water with pumps within the region,and building reservoirs and diverting water outside the region.Based on the construction content and engineering investment of each water supply guarantee scheme,and after technical and economic comparison,the scheme of lifting water with pumps within the region is recommended for the ship lock water supply guarantee.

Abstract:In view of the problem that the shipping demand in the upper reaches of the Yangtze River is large but there are many shoals and rapids leading to insufficient water depth,this paper conducts a study on the minimum navigable water depth of the Luzhou section of the upper reaches of the Yangtze River.The minimum designed navigable flow rate for this river section is 3 396 m3/s,which is determined using the comprehensive duration curve method and the guarantee rate frequency method.The numerical model is used to simulate the Bingpanqi,Pangxieqi,and Wayaotan waterways.Based on the water depths of five typical shoal and rapid sections,the response relationship between shoals and rapids and navigable flow is established.It is concluded that when the navigation width of the typical shoal and rapid sections in this river section is 110 m,the corresponding minimum navigable water depth is 3.39 m,which meets the water depth and navigation width standards of Class II waterways.The research results can provide support for the later channel construction planning of the Luzhou section of the upper reaches of the Yangtze River and facilitate the construction of high-grade waterways in the Luzhou section.

Abstract:The built Longtoushan Junction on the Ganjiang River is situated on a bend,where the upstream and downstream approach channels of the first-line ship lock on the right bank are located in the main flow area.Affected by hydro-junction operation and incomplete construction,the navigation flow conditions remain poor.The second-line ship lock is planned to be constructed on the right side of the existing first-line ship lock.Comprehensive improvements are proposed to improve the flow condition,such as reducing the porosity rate of existing partition walls and extending the length,constructing additional guide walls and berthing piers for the first-line ship lock and building new downstream revetments with complementary dredging measures.The layout scheme of the second-line ship lock is optimized comprehensively.Navigable water flow conditions for the two ship locks are validated by physical model tests under typical operating conditions involving joint operation of the power plant and dam.The results demonstrate that implementing the new wall structure can decrease the partition wall permeability low than 20%.Uniform opening patterns for sluice gates are adopted,and 20# to 24# holes adjacent to the ship locks maintain partial opening when flood discharges reach once in two years specifically.The maximum navigable discharge of the first-line ship lock can increase from 5,000 m3/s to once in five years (15,100 m3/s),while the second-line ship lock can also achieve navigation flow of once in five years.

Abstract:The second phase of the remediation project of Minjiang River Passage and the deepening project of the Minjiang River Estuary Barrage Sand Channel have been completed for 26 and 16 years respectively.During the period the conditions of upstream runoff and sediment have undergone great changes.The distribution pattern of the seashore and trough outside the mouth has changed greatly,and a series of problems such as the danger and siltation of navigable ships have occurred in individual sections.The waterway in the estuary area is affected by multiple factors such as runoff,tidal currents and waves,and it is in the process of continuous dynamic changes of scouring and silting,which is difficult to remediate.Based on the maintenance mapping and related data in the past 15 years,this paper summarizes the existing problems and analyzes the reasons for the current Minjiang waterway,and concludes that further governance of seaward channel of Minjiang River is necessary to ensure the safety of ship navigation.At the same time,further governance schemes such as adjusting the route of local sections,throwing bagged sand chain blocks outside the mouth to fix the beach and sand are put forward.It is also suggested that maintenance and restoration may not be necessary if local erosion of the inverted fish mouth dam or submerged dam is found.

Abstract:The application of virtual aids to navigation(V-AtoN) is of great significance in excavating navigation depth,reducing maintenance costs,and improving navigation assistance efficiency.To solve the problems existing in the application of V-AtoN on the Yangtze River,a preliminary application model for V-AtoN is established.Three types of application scenarios for V-AtoN enhancement,substitution,and addition are proposed.The display method of combining circular and entity AtoN symbols,solid and dashed line distinguishing synthesis from virtual,and text distinguishing publishing carriers are defined.A publishing method that the permanent V-AtoN issued by AIS should be published on the electronic navigational charts is proposed.Thus,the application mode of V-AtoN on the main line of the Yangtze River is initially established,and demonstration applications have been carried out based on digital waterways and electronic navigational charts.The research result can provide reference for the standardized application of V-AtoN on inland rivers.

Abstract:In view of the problems of insufficient depth in data fusion and intelligent application of unmanned aerial vehicle and unmanned vessel data in the Yangtze River trunk digital production business system,efficient data transmission,multi-source data fusion technology,and key channel element target recognition and dynamic behavior detection analysis technology are adopt to conduct research on fusion and intelligent application of unmanned aerial vehicle and unmanned vessel in digital channels.The development of an intelligent perception and recognition analysis module for channel elements is completed on the basis of unmanned aerial vehicle and unmanned vessel data,as well as the development of an auxiliary decision-making module and intelligent data terminal for digital channels.These developments enhance the auxiliary decision-making functions of channels are enhanced by these developments,and the intelligence of auxiliary decision-making is improved.An intelligent application model for unmanned channel patrols is built,and integrated and intelligent applications of unmanned aerial vehicle and unmanned vessel in the Yangtze River channel are achieved.

Abstract:Due to the poor performance of deep learning-based detectors in the past,scale variations,background variations,and visual occlusions reduce the accuracy of raw image localization.Therefore,an improved YOLOv5s+DeepSORT model is proposed to enhance adaptability to dock environments.To enhance the robustness of multi-scale loading objects,multi-scale convolution is embedded in YOLOv5s,and an efficient pyramid segmentation attention(EPSA) network is added to achieve more powerful feature fusion multi-scale representation.The mean average precision(mAP) is improved from 90.05% to 90.90%.By optimizing the original classification loss function through distributed sorting loss,the impact of imbalanced loading objects and background changes in dock image sequences is reduced,resulting in a 4.8% improvement in multiple object tracking accuracy (MOTA).Experiments on self built datasets show an average accuracy of 90.9% and a detection accuracy of 92.2%.

Abstract:Aiming at the problems of large deformation calculation errors and low accuracy in numerical analysis methods for foundation pit engineering,a geological parameter inversion analysis method based on GWO-SVR is proposed in combination with existing monitoring data,which can achieve more accurate deformation calculation of foundation pits,especially suitable for foundation pits with significant deformation.On this basis,the causes of large deformation during the excavation process of adjacent anchor cable foundation pits are studied,and two different deformation control measures are compared and calculated.The effectiveness of the treatment measures is analyzed through measured data.The selection of the spacing between anchor cable foundation pits has a significant impact on the stability of the foundation pit and the stress of the supporting structure.By using numerical analysis methods,the deformation and internal forces of the foundation pit support piles,anchor cable forces,and soil pressure between piles under different spacing conditions are proposed.This can achieve differentiated design of the supporting structure for anchor cable foundation pits under different spacing conditions,providing reference for the selection and calculation analysis of anchor cable foundation pits.

Abstract:Different projects have different requirements for post-work settlement.The inconsistent understanding of unloading standards encounters in the process of soft foundation treatment.Relying on an actual project,we use the hyperbolic method,three-point method and Asaoka method to calculate and analyze respectively.The results show that the unloading standard is more reasonable with consolidation degree as the main and settlement rate as the supplementary.The prediction result of three-point method is larger when calculating the consolidation degree,and it is appropriate to choose the points with the time interval of 25 d in the gentle section of curve.The prediction result of hyperbolic method is smaller,but the human influence is large,and it is necessary to exclude the previous data and anomalous data in the fitting.The Asaoka method is appropriate to choose the interval of 5 to 10 d,so as to be in good accordance with the actual measurement results.In actual projects,it is necessary to combine a variety of methods and actual observation data to comprehensively judge the degree of soft soil consolidation,in order to improve the accuracy and reliability of the prediction.

Abstract:In recent years,the “Belt and Road” initiative has been deeply connected with Saudi Arabia's “Vision 2030”,and more and more Chinese companies have participated in Saudi Arabia's infrastructure construction.In view of the complex geological conditions and high foundation control standards in Saudi Arabia,combined with the project practices of Chinese companies in Saudi Arabia in recent years,the geological and special geotechnical conditions of the Kingdom of Saudi Arabia (referred to as “Saudi Arabia”) are summarized and analyzed.Based on this,a comprehensive evaluation method for dredging excavability and a refined control process for the fine particle content of hydraulic filling are proposed.The applicability of vibro-compaction and dynamic compaction methods for large-area sandy foundations and methods for coral reef sand foundation treatment are summarized.A foundation treatment inspection and acceptance method based on in-situ testing technology is proposed,in order to provide technical support for Chinese companies to participate in engineering construction in Saudi Arabia.

Abstract:Percussion hammer drilling is a common method to solve the underwater reef-clearing task under ecological constraints.To improve the crushing efficiency of the reef without a free surface,this paper put forward the underwater shock hammer drilling technology combining drilling with impact hammers.Through the underwater drilling and impact hammer reef breaking field test,considering the water resistance effect of impact hammer movement in water and the cable drag effect,the impact hammer collision and penetration model under the influence of drilling is established.Combined with the 3DEC numerical simulation of drilling and impact hammer reef breaking,the damage evolution law of repeated impact of the hammer on the reef under the action of drilling is analyzed.The results show that drilling has no obvious effect on increasing the penetration depth of the underwater impact hammer,but the breaking depth and width of the reef can be significantly improved when the drop distance is below 10 m,and the reef cleaning efficiency can be increased by 183%.Hammer drop distance and drilling depth are the main controlling factors of reef-breaking efficiency.Under the combined action of drilling and impact hammer,the crushing volume after 5 shocks is about 103.24 times that of the first impact.Both drilling and multiple shocks can effectively improve the reef-clearing efficiency of the hammer,and drilling can further improve the reef-breaking efficiency of the hammer under multiple shocks.The research results can provide a reference for parameter design and site construction of underwater environmental protection reef clearing.

Abstract:To risk of damage to existing submarine pipelines and cables during the construction of new projects in marine engineering,this paper takes the construction of approach bridge crossing submarine pipelines as an example,and systematically elaborates and analyzes the key construction ideas and technical applications of crossing pipeline engineering around the protection of submarine pipelines during on-site construction.The conclusion indicates that underwater exploration of submarine pipelines is still the most direct and effective way to determine the location of pipelines.Before exploration,sufficient analysis for pipeline information should be conducted,and safe techniques to pipeline surface dredging should be adopted.After determining the location of the pipeline,accurate and clear pipeline markings and vessel traffic signs should be set up at sea before construction to achieve visualization of the underwater pipeline and maritime traffic.Considering account various working conditions,Pre-fixed anchors can greatly reduce the risk of ship anchoring,and multi-level monitoring during construction is also an important measure to ensure pipeline safety.

Abstract:The multi-factor allocation model for large-scale earthwork transportation in Pinglu Canal involves not only a large amount of earthwork excavation,transportation,and disposal in construction projects,but also is constrained by many factors such as topography,transportation conditions,environmental protection requirements,construction time windows,cost budgets,etc.A linear programming model is constructed to define decision variables on the basis of engineering practice by systems theory and optimization theory.The key variables for decision-making are clarified,such as excavation volume,transportation volume,and consumption volume of soil and stone at different locations.An objective function is constructed on the basis of engineering objectives to minimize potential costs such as transportation cost,processing cost,and time cost.A linear programming solver is used to solve the model,and the optimal earthwork allocation plan is obtained.Actual data on excavation,transportation,and disposal of earth and stone are collected in real time during the construction process,then measured data collected are iterated feedback and optimized.The measured data are compared with the predicted results of the model,and the reasons for the differences are analyzed.The factors that are inconsistent with the actual situation or not considered are optimized and adjusted.The model parameters or constraints are adjusted on the basis feedback.According to the optimized model results,the construction plan and resource allocation to improve efficiency and reduce costs are adjusted.The successful application of this allocation model in canal and waterway engineering has important theoretical significance and engineering practical value.

Abstract:For the topographic surveying in shallow coastal waters,there are some problems of high risk of running aground,low efficiency and poor safety of traditional shipborne acoustic depth measurement methods,and the cumbersome implementation process and insufficient accuracy of remote sensing retrieval of water depth and dual-medium photogrammetry methods.The low-altitude photogrammetry technology of unmanned aerial vehicle(UAV) is adopt to innovatively integrate into the navigation tide level correction model.A new topographic surveying method for shallow coastal waters on the basis of the low-altitude UAV is proposed and successfully applied in practical engineering.The results show that the method avoids the risks and limitations of traditional measurement methods effectively,and improves the working efficiency and safety significantly.The tidal level correction model during navigation in this method can eliminate the influence of tidal level error,and improve the accuracy of bottom topography surveying in shallow water area.The results not only provide a new,efficient and accurate method for the topographic survey of coastal shallow water area,but also provide a new technical idea and direction for the practical application in related fields.

Abstract:Aiming at the problems of long slurry transportation distance and high energy consumption of DN850 pipeline in large-scale dredging and reclamation projects,the energy-saving effect of pipeline aeration technology under the conditions of transporting fine sand and silt-containing soil is studied by using the method of field tests and relying on the Xiamen Airport's Da-Xiaodeng Land Reclamation Project.The results indicate that aeration technology is suitable for large-diameter pipelines and fine sandy silt soils,reducing the slurry transportation resistance of DN850 pipeline by approximately 5%,increasing the reclamation discharge distance by about 5%,and reducing the oil consumption the backfill construction by approximately 3.84%.Field tests have proved that the energy-saving technology for conveying sludge through the discharge pipe of cutter suction dredgers can reduce the number of sludge pumps opened and the conveying resistance,and the equipment investment cost is low,which provides a new technology for energy conservation and emission reduction of cutter suction dredgers.