Three Dimensional Numerical Modelling And Analysis Of Hydronic Heating System For Snow Melting And Deicing On Bridge Deck

Transportation is the foundation of the national economy,and highway is the key part of our road traffic system.According to statistics,more than 70 percent of China’s roads are affected by ice and snow in winter,leading to more traffic accidents,smaller road capacity and lower transportation efficiency.However,the currently commonly used "passive" deicing and snow removal/melting technologies,such as mechanical methods and chemical snow melting methods,have some disadvantages such as low snow removal efficiency and great environmental pollution damage.As people pay more and more attention to the driving condition of road surface,durability protection of road structures,low-carbon development and environmental protection,hydronic pavement and many other "active" deicing and snow-melting technologies have attracted more and more attention.Hydronic heating system in an active,green and efficient technology for deicing and snow-melting on pavement.Researchers have carried out many studies on the snow-melting efficiency of hydronic pavement and its influencing factors,through theoretical analysis,numerical simulations,indoor and outdoor experiments and observations.In order to address the above problems,a three dimensional(3D)numerical analysis model of the snow-melting efficiency of the hydronic technology was constructed through custom setting and development based on Comsol Multiphysics software platform,focusing on the typical "asphalt concrete+cement concrete" bridge deck.Based on the thermal and mechanical coupling calculation,the changes and distribution characteristics of the temperature stress and strain during the heating process in bridge deck were analyzed.And the research results are used to guide the design and implementation of the shallow geothermal energy based hydronic heating system for Baierya Bridge of the first tourist highway S103 in Shandong Province.The main contents and conclusions are as follows:According to the structural characteristics of asphalt concrete+cement concrete type bridge deck,a simple 3D unsteady heat conduction model of pavement was constructed,and the complex boundary of heat and mass transfer between"pavement-snow layer-environment" was defined and treated.Based on Comsol Multiphysics software platform,above models were solved numerically,and the simulation results were processed after the computation.By comparing with experimental and numerical simulation data in literature,the accuracy of the 3D numerical model analysis method for snow-melting efficiency is validated.Using the developed 3D numerical simulation method,the influences and rules of key parameters such as buried pipe spacing,buried pipe depth,snow layer thickness,initial temperature and pipe size on snow-melting efficiency of the hydronic heating system on bridge deck were studied,and the design values of key parameters were recommended.The temperature loss along the pipeline and its effect on the uniformity of snow melt on the bridge deck were analyzed.Based on the numerical model of thermal-mechanical coupling analysis,the variation and distribution characteristics of temperature stress and strain in the bridge deck during fluid heating process were revealed.Combined with the characteristics of Baierya Bridge of S103 tourist highway and the geothermal and climatic characteristics of Jinan,the design method of shallow geothermal energy based hydronic heating system for deicing and snow-melting was studied,and the key design parameters,technical requirements and monitoring and evaluation scheme of underground and in-bridge heat exchange systems were proposed,and the practical application of the project was completed.The relevant results of this study can provide reliable technical supports for follow-up evaluation of the snow-melting efficiency of the hydronic heating system on Baierya Bridge and applications to other similar projects.