Corrosion is one of the main causes of damage and leakage in oil and gas pipelines,and accurately predicting the corrosion rate is crucial for pipeline safety.This study established a model based on the Sparrow Search Algorithm(SSA)-optimized Light GBM to predict the average corrosion rate of oil and gas pipelines.Meanwhile,the study employed the Synthetic Data Augmentation(SDA)technique to expand the dataset,enhancing the accuracy and stability of the model;and evaluated the model performance through comparative analysis.In the study,the Sparrow Search Algorithm(SSA)was first used to optimize the parameters of the LightGBM model,forming the SSA-LightGBM model.This model was then used to train and predict the corrosion rate of oil and gas pipelines,and the error and stability of the prediction results were analyzed.The results show that the SSA-LightGBM model has high accuracy and stability in predicting the average corrosion rate of oil and gas pipelines.In addition,the prediction results of the SSA-LightGBM model were compared with those of other models such as LightGBM,GBRT,CatBoost,SSA-GBRT,and SSA-CatBoost.The results indicate that the SSA-LightGBM model performs best in terms of accuracy and stability.
In recent years,global warming has led to an increase in extreme weather&climate events.Many cities have formulated systematic plans for waterlogging control in accordance with relevant documents.However,due to insufficient coordination with external systems in planning&design,the system lacks the guidance.From the three levels of upper planning,special planning and construction plan,it studies the connecting points between the systematic implementation plan of waterlogging control,related planning&design.Through the overall planning&feedback of population,land use,coordinate system,blue&green space,flood control&drainage,vertical elevation,sponge city,underground tunnel,co-treatment of rain&pollution,and timely scheduling of construction projects,etc.To realize the transmission&landing of the upper planning,the coordination of the special planning system&the consolidation of the construction plan,so as to avoid the possible contradictions&conflicts with the existing planning&design in different lines,strengthen the connection of relevant majors&projects,and improve the work efficiency,systematicness,scientificity&implementability of the implementation plan.
The reinforcement of underground structures is mostly controlled based on crack width.It analyzes the changes in economic reinforcement of underground structures under different steel bar spacing,internal force size,&material price conditions by enumerating within a certain range.The results indicate that there is not much difference between the economic reinforcement ratios based on crack control&strength control,but the variation patterns are not consistent.The structural cost will decrease with an increase in structural reinforcement ratio and a decrease in component size,especially when the unit price of concrete is high.The economic reinforcement ratio of the structure will approach or even exceed the maximum reinforcement ratio.When only considering the main reinforcement,a high reinforcement ratio can reduce the structural cost by 7.6%.Through simple examples,it is verified that the reinforcement scheme can reduce the overall cost of the structure by 15%.
With the gradual aging of urban population in recent years,the humanistic concept of people's cities for the people has been increasingly valued by departments at all levels.The improvement of pedestrian bridges in terms of convenience&comfort has become an urgent need for construction&improvement.Taking Yan'an Road Jiangsu Road Pedestrian Bridge Improvement Project in Shanghai as the starting point,combined with the travel needs of surrounding communities,it studies the aging adaptation strategy,and expounds some experiences and methods in the improvement of municipal building facilities from the perspective of barrier-free transformation and architectural landscape improvement.While improving the renovation of the project's age-appropriate function,it also provides a new idea for the age-appropriate transformation of other municipal building facilities to some extent.
Based on the in-situ suspension protection project of a large-diameter sewage pipeline crossing the auxiliary foundation pit at a station in Kunming Rail Transit L2 Phase II,a pipeline in-situ suspension protection system of concrete beam support+support hanger+vertical suspension rod+crossbeam is established,and a 3D numerical model of the suspension protection system is established using numerical simulation methods.At the same time,considering the influence of factors such as beam steel type,support&hanger steel type,steel spacing,and steel grade,different suspension system schemes are proposed,and the stress&deformation laws of each component structure are calculated based on the proposed numerical model.The results show that the optimal solution is the in-situ pipeline suspension system with section steel grade Q235,beam type H200×204×12×12,support hanger&vertical boom type H100×100×6×8 and section steel spacing of 800 mm.The scheme has high reliability&reasonable economy,and the research results can provide guidance&reference for the subsequent research on in-situ protection technology of pipelines crossing foundation pits.
To accurately apply temperature gradients in the design of composite steel small box girders,a refined finite element model is established in combination with practical engineering.The spatial temperature field of composite steel small box girders in natural environments is analyzed and the temperature gradient mode is summarized.The results show that the temperature field of different parts of the steel small box girder varies greatly.The vertical temperature gradient of composite steel small box girder differs significantly from the double line mode specified in the specifications,and the vertical temperature gradient can be simplified into a four line mode.As the thickness of the concrete bridge deck increases,the temperature gradient inside the bridge deck gradually changes from linear to nonlinear,and a negative temperature gradient appears.The research results can provide reference for applying temperature gradient loads in the design of similar bridges.
Taking the E ast Meihua Road Tunnel under the Xingye Express Line(North Section)in Zhuhai as the engineering background,the theoretical calculation results&engineering monitoring data are compared to analyze the mechanical characteristics of the ultra large cross-section rectangular top pipe joint under typical geological conditions of upper soft&lower hard in southern China.Through research,it has been found that the force distribution of the structure under this geological condition is not uniformly&symmetrically distributed under ideal conditions.The commonly used theory of soil pressure calculation is more suitable for upper soft soil strata.The discreteness of soil pressure distribution in lower hard strata is greater than that in upper soft soil strata.The bottom hard rock creates strong constraints on the bottom support,resulting in differences in the symmetrical shape of the force on both sides of the structure compared to the ideal state.
The treatment measures for large-span wall panels are the focus of structural design for large rectangular underground pumping stations.Taking a sewage pump station in an ecological city in Guangdong as an example,it proposes three structural design methods for large-span side walls and bottom plates:vertical closed frame,horizontal closed frame and plate column structure system.Detailed calculation&analysis are conducted for each method.The results indicate that the scheme of adding vertical closed frames is the most economically reasonable.On this basis,a comprehensive demonstration&comparison will be conducted to provide reference for similar engineering designs in the future.
It provides an in-depth analysis of the design scheme for the supporting bridge engineering of the Guangzhou Branch of National Library of Editions,introduces the overall&local treatment in the process of bridge landscape design&modeling,and analyzes the bridge structure design scheme&innovative points.At the same time,finite element simulation analysis of structural safety is conducted from the aspects of structural strength,stiffness,and stability.The relevant results can provide reference for similar projects.
A certain bridge is a 3-span cable-stayed prestressed continuous wide box girder bridge.After removing the formwork of the box girder,it is found that a large number of cracks appeared in the bottom plate area,including longer longitudinal cracks.By establishing a solid finite element model for stress analysis of the bridge,it is found that the crack resistance performance of the bridge meets the requirements of the specifications.Bottom plate cracks are not the main stress cracks,and the cracks may be caused by a combination of environmental,construction and structural complexity factors.Corresponding improvement suggestions are proposed.
In response to the poor visibility caused by the daily large diversion&discharge water diversion mode in the main channel of the Taopu River at present,an optimization study is conducted on the upstream pump gate scheduling mode of the Taopu River through simulation analysis of 1 D hydrodynamic&material transport models.The simulation results of multiple working conditions show that during dry days,the water diversion flow rate of the Mudu Port pump gate is 5 m3/s,and the water diversion duration is 8 hours.Under the working condition,the flow velocity along the Taopu River reaches 0.05 m/s,which is moderate.The entire river channel diverts water for 5.44 days,which can meet the Class IV standard for surface water.The water quality improvement effect is good,and it can also consider economic benefits.The research results can provide effective data support for the environmental treatment of Taopu River and the optimization scheduling of Mudu Port pump gates.
As a key area in the starting area of Xiong'an New Area,the start-up zone bears the responsibility of exploring development and construction models,piloting policy measures,and showcasing the embryonic form of the new area.At present,the drainage network system and planned river water system within the start-up area have not yet been formed,and there is a high risk of drainage.The construction of temporary drainage projects during the flood season urgently needs to be carried out.The study analyzes the natural topography of the start-up area,the direction of rainwater discharge inside and outside the area,selects design elements and technical standards based on boundary conditions,and compares the design schemes of drainage facilities.After the completion of the project,it will provide strong support for the safe flood control of the construction project in the start-up area.The research experience can provide reference for solving drainage problems during the construction period of other similar engineering projects.
A broken pile occurred on the ramp of an interchange bridge,and the cause was poor pouring quality at the connection between the pier and the pile foundation,which resulted in a deflection of the main beam of 16.7 cm;the cracking of the main beam top and bottom plate penetrated the web,with a maximum crack width of 0.6 mm.By calculating the steel stress from the crack width,it was found that when the crack width was greater than 0.3 mm,the steel in the main beam had already yielded,and the steel in the severely cracked areas of the main beam bottom plate on the top of pier TA1,the main beam top plate on the top of pier TA0 and TA2 had already yielded or even fractured.In response to these defects,the pier was reinforced by adding a pile cap,and the pier was reinforced by re-pouring.The main beam bottom plate and web were reinforced by bonding steel plates and carbon fiber cloth,and the cracked area of the top plate was reinforced by chiseling the bridge deck pavement,covering it with main reinforcements,and re-pouring to improve the bearing capacity.After the reinforcement,the bridge has been in normal operation for more than ten years,which can provide reference for similar projects.
In the context of the national Government Online-Offline and streamline the government,delegate power,a n d improve government services,Shanghai has integrated the multiple matters related to functional departments into one matter from the perspective of enterprises&the public.The Shanghai Water Bureau closely follows national policies,reforms the approval system for river related water projects,opens up the approval channel for river related one matter,and achieves full online processing.Taking a special maintenance project for a certain embankment in Huangpu District,Shanghai as an example,it elaborates on the approval process in detail,greatly shortens the service process through full online handling,proposes innovative directions for cross basin handling and expansion of one matter,further enhances the collaborative service ability of water administrative approval work,and achieves precise service to the needs of enterprises&the public.
There are many methods for solving the cable forces of conventional cable-stayed bridges in a reasonable state of completion,but when directly used for solving the cable forces of complex space multi-segment cable shaped tower cable-stayed bridges,it is often difficult to quickly obtain more reasonable results.To solve the problem of cable force calculation for complex space multi-segment cable shaped tower cable-stayed bridges,a step-by-step calculation method for cable force based on structural isolation method is adopted.Taking the main bridge of Jueshui Bridge I in Suizhou,Hubei as the calculation object,the cable forces of a complex spatial multi-segment cable-stayed bridge with irregular towers are solved,and a reasonable cable force for the completed bridge is obtained.The results show that the method can simplify the reasonable calculation process of cable tension for complex space multi-segment cable-stayed bridges with irregular towers,and obtain good initial cable tension values.The method is simple&effective.
The use of segmental prefabricated assembly of cover beams can reduce the quality of prefabricated segments.Two analysis methods,namely the assumption of plane section&solid finite element method,are used to calculate the normal stress of the joint of the prefabricated cover beam under temporary prestress.The results indicate that there is a certain degree of non-uniformity in the stress distribution of the joint section in the background engineering,but it is generally close to the calculation results assumed by the plane section.For the construction method of installing cantilever arms for crawler cranes,the crane and temporary prestress load need to be gradually converted.The construction sequence determined through empirical calculation and optimized by nonlinear programming can ensure that the compressive stress on the joint section during the construction process is not less than the target value and as uniform as possible.
With the continuous acceleration of urbanization in China and the rapid increase in transportation demand,higher requirements have been put forward for the carrying capacity of urban road traffic.The current trend of road reconstruction projects is increasing year by year.The bridge renovation plan for some complex nodes in the central urban area involves the renovation of existing old bridges,often requiring comprehensive consideration of multiple factors such as engineering waste,investment,environmental&traffic impacts,which is the focus and difficulty of the renovation project.Taking the renovation of the Shangpu Road node in the rapid renovation project of Jiyang Road in Shanghai as an example,it explores the overall renovation plan of the node,especially innovatively proposing a renovation plan that only replaces the edge beam to meet the increase of sound barrier load,and strengthens the design of the joint structure to meet the stability of overturning.Its experience can provide reference&inspiration for similar projects.
There are many horizontal&plane connections in the upper part of conventional steel truss bridges,which affect the permeability&landscape effect of the bridge.However,open steel truss bridges can better solve the problem&make them more widely used in urban bridges.Taking the Luoxizhou Bridge in Ganzhou as an example,the overall stress performance of a large-span open steel truss bridge is analyzed.On the basis of overall analysis,select the isolation body model with the most unfavorable stress for local finite element analysis.The maximum equivalent stress in the upper part of the local model occurs at the node plate connection between the diagonal&vertical web members,while the maximum equivalent stress in the lower part of the local model occurs at the junction of the longitudinal support stiffeners&the transverse partition of the main beam,and the peak stress is smaller than the yield stress of the steel.Therefore,attention should be paid to the design of stress concentration areas at the nodes of large-span open steel truss bridges,which also provides some reference for the node design&analysis of similar bridges.
The micro-flocculation sand filtration process is applied to the deep treatment of urban sewage treatment plants.A pilot plant is used to study the effect of filter layer thickness on the removal of CODCr,TP,ammonia nitrogen,and SS in the sand filter.Samples are taken from the V-shaped filter of the micro-flocculation sand filtration process in a sewage treatment plant in Kunshan to study the effect of filter layer thickness on the removal of total coliform bacteria in the sand filter.The results show that when the filtration speed is 5～9 m/h,the retention of TP in the water by the sand filter mainly occurs within the 0～90 cm filter layer.At this time,the effluent can meet the Class A standard of GB 18918-2002 Pollutant Discharge Standard for Urban Sewage Treatment Plants.The micro flocculation sand filtration process can effectively ensure the biological safety of the effluent.Under the dual effects of flocculation reaction&physical interception,the total number of coliform bacteria can be reduced by 1～1.7 orders of magnitude.
In rainy weather,the water film formed on asphalt pavement has a very important impact on driving safety.However,traditional anti-skid performance detection methods are difficult to reflect the dynamic changes of anti-skid performance in real time when there is water film on the road surface.A high-precision,long-range,and durable water film thickness sensor is designed based on the principle of fiber optic pressure measurement,focusing on real-time perception of water film thickness on asphalt pavement in wet and slippery conditions.A method for analyzing water film thickness data is proposed through temperature compensation,time series modeling,and other methods.The accuracy of the water film thickness sensor is verified through indoor experiments.The experimental results show that the pressure-sensitive water film thickness sensor can be used for real-time sensing of water film thickness on asphalt pavement,providing technical support for driving safety on rainy roads.
