含黄铁矿高铁路基填料氧化反应细观演化规律与膨胀机理OA

Oxidation-induced expansion of pyrite-bearing railway subgrade filler is a significant cause of subgrade heaving diseases,yet its meso-scale evolution patterns and deformation mechanisms under the coupled effects of water,air,and heat remain unclear.To investigate the heaving deformation characteristics of pyrite-bearing high-speed railway subgrade and the meso-macro evolution mechanisms of the filler,this paper takes pyrite-bearing subgrade filler as the research object.Controlled variable tests are conducted by regulating oxygen concentration and temperature,monitoring the leaching behavior of ions such as SO24-.Combined with techniques including X-Ray Diffraction(XRD)and Scanning Electron Microscope(SEM),the mineral transformation processes and pore structure evolution characteristics are tracked.The influence patterns of environmental factors on the pyrite oxidation rate and product formation are analyzed,revealing the microstructural deterioration mechanism and the evolution process of expansion deformation induced by the oxidation reaction.The results show that oxygen concentration is the dominant factor affecting the initial oxidation rate of pyrite,while high temperatures significantly accelerate product formation and structural degradation.Under high-oxygen and high-temperature conditions,the SO24-concentration in the samples increased markedly,accompanied by the formation of numerous microcracks and flaky secondary mineral precipitates,and the internal structure transitioned from dense to loose,exhibiting distinct expansive characteristics.The oxidation process was also accompanied by carbonate dissolution,cementation breakdown,and iron salt precipitation,which further intensified the disintegration and volumetric expansion of the material.Under the coupled effects of water,air,and heat,pyrite-bearing subgrade fillers are prone to oxidation-induced expansion,resulting in local structural disturbance and volume growth,ultimately causing subgrade heave deformation of high-speed railway.The research results can provide a theoretical basis and technical support for the prevention and engineering treatment of subgrade heave disease in high-speed railways.