Red-bed mudstone, prevalent in southwest China, poses a formidable challenge due to its hydrophilic clay minerals, resulting in expansion, deformation, and cracking upon exposure to moisture. This study addresses upli...Red-bed mudstone, prevalent in southwest China, poses a formidable challenge due to its hydrophilic clay minerals, resulting in expansion, deformation, and cracking upon exposure to moisture. This study addresses uplift deformation disasters in high-speed railways by employing a moisture diffusion-deformation-fracture coupling model based on the finite-discrete element method(FDEM). The model integrates the influence of cracks on moisture diffusion. The investigation into various excavation depths reveals a direct correlation between depth and the formation of tensile cracks at the bottom of the railway cutting. These cracks expedite moisture migration, significantly impacting the temporal and spatial evolution of the moisture field. Additionally, crack expansion dominates hygroscopic deformation, with the lateral coordinate of the crack zone determining peak vertical displacement. Furthermore, key factors influencing deformation in railway cuttings, including the swelling factor and initial moisture content at the bottom of the cutting, are explored. The number of tensile and shear cracks increases with greater excavation depth, particularly concerning shear cracks. Higher swelling factors and initial moisture contents result in an increased total number of cracks, predominantly shear cracks. Numerical calculations provide valuable insights, offering a scientific foundation and directional guidance for the precise prevention, control, prediction, and comprehensive treatment of mudstone-related issues in high-speed railways.展开更多
为了对红层软岩生态防护边坡的抗冲刷能力进行定量研究,采用现场模拟降雨的方法,测量不同雨强降雨时红层软岩生态防护坡面的径流量、坡体截留量和冲蚀量.试验结果表明,在雨强为20 mm/h持续降雨190 m in和雨强为50 mm/h持续降雨120 m in...为了对红层软岩生态防护边坡的抗冲刷能力进行定量研究,采用现场模拟降雨的方法,测量不同雨强降雨时红层软岩生态防护坡面的径流量、坡体截留量和冲蚀量.试验结果表明,在雨强为20 mm/h持续降雨190 m in和雨强为50 mm/h持续降雨120 m in的情况下,采用植被防护的红层软岩边坡基本未冲蚀;生态防护能有效阻碍红层软岩在水环境作用下进一步风化崩解,从而降低红层软岩坡体的冲蚀.展开更多
In this study,the axial swelling strain of red-bed mudstone under different vertical stresses are measured by swell-under-load method,and the microstructure of mudstone after hygroscopic swelling is studied by mercury...In this study,the axial swelling strain of red-bed mudstone under different vertical stresses are measured by swell-under-load method,and the microstructure of mudstone after hygroscopic swelling is studied by mercury intrusion porosimetry(MIP).The weakening coefficient and Weibull distribution function are introduced into the coupling model of mudstone moisture diffusion-swelling deformation-fracture based on finite-discrete element method(FDEM).The weakening effect of moisture on mudstone's mechanical parameters,as well as the heterogeneity of swelling deformation and stress distribution,is considered.The microcrack behavior and energy evolution of mudstone during hygroscopic swelling deformation under different vertical stresses are studied.The results show that the axial swelling strain of mudstone decreases with increase of the vertical stress.At low vertical stresses,moisture absorption in mudstone leads to formation of cracks caused by hydration-induced expansion.Under high vertical stresses,a muddy sealing zone forms on the mudstone surface,preventing further water infiltration.The simulation results of mudstone swelling deformation also demonstrate that it involves both swelling of the mudstone matrix and swelling caused by crack expansion.Notably,crack expansion plays a dominant role in mudstone swelling.With increasing vertical stress,the cracks in mudstone change from tensile cracks to shear cracks,resulting in a significant reduction in the total number of cracks.While the evolution of mudstone kinetic energy shows similarities under different vertical stresses,the evolution of strain energy varies significantly due to the presence of different types of cracks in the mudstone.The findings provide a theoretical basis for understanding the hygroscopic swelling deformation mechanism of red-bed mudstone at various depths.展开更多
A Danxia landform is a red-bed landform characterized by steep cliffs. It was initially discovered and named by Chinese scholars. Although there are red-bed landforms in many parts of the world, China, with a special ...A Danxia landform is a red-bed landform characterized by steep cliffs. It was initially discovered and named by Chinese scholars. Although there are red-bed landforms in many parts of the world, China, with a special fondness for the color red, boasts the most widely distributed Danxia possessing unique characteristics. This is a mesmerizing natural formation and a special gift that nature has bestowed upon this country.展开更多
基金funded by the National Natural Science Foundation of China (No. 42172308, No.51779018)the Youth Innovation Promotion Association CAS (No. 2022331)the Science and Technology Research and Development Program of China State Railway Group Co., Ltd. (No. J2022G002)。
文摘Red-bed mudstone, prevalent in southwest China, poses a formidable challenge due to its hydrophilic clay minerals, resulting in expansion, deformation, and cracking upon exposure to moisture. This study addresses uplift deformation disasters in high-speed railways by employing a moisture diffusion-deformation-fracture coupling model based on the finite-discrete element method(FDEM). The model integrates the influence of cracks on moisture diffusion. The investigation into various excavation depths reveals a direct correlation between depth and the formation of tensile cracks at the bottom of the railway cutting. These cracks expedite moisture migration, significantly impacting the temporal and spatial evolution of the moisture field. Additionally, crack expansion dominates hygroscopic deformation, with the lateral coordinate of the crack zone determining peak vertical displacement. Furthermore, key factors influencing deformation in railway cuttings, including the swelling factor and initial moisture content at the bottom of the cutting, are explored. The number of tensile and shear cracks increases with greater excavation depth, particularly concerning shear cracks. Higher swelling factors and initial moisture contents result in an increased total number of cracks, predominantly shear cracks. Numerical calculations provide valuable insights, offering a scientific foundation and directional guidance for the precise prevention, control, prediction, and comprehensive treatment of mudstone-related issues in high-speed railways.
文摘为了对红层软岩生态防护边坡的抗冲刷能力进行定量研究,采用现场模拟降雨的方法,测量不同雨强降雨时红层软岩生态防护坡面的径流量、坡体截留量和冲蚀量.试验结果表明,在雨强为20 mm/h持续降雨190 m in和雨强为50 mm/h持续降雨120 m in的情况下,采用植被防护的红层软岩边坡基本未冲蚀;生态防护能有效阻碍红层软岩在水环境作用下进一步风化崩解,从而降低红层软岩坡体的冲蚀.
基金funded by the National Natural Science Foundation of China(No.42172308)the Youth Innovation Promotion Association CAS(No.2022331).
文摘In this study,the axial swelling strain of red-bed mudstone under different vertical stresses are measured by swell-under-load method,and the microstructure of mudstone after hygroscopic swelling is studied by mercury intrusion porosimetry(MIP).The weakening coefficient and Weibull distribution function are introduced into the coupling model of mudstone moisture diffusion-swelling deformation-fracture based on finite-discrete element method(FDEM).The weakening effect of moisture on mudstone's mechanical parameters,as well as the heterogeneity of swelling deformation and stress distribution,is considered.The microcrack behavior and energy evolution of mudstone during hygroscopic swelling deformation under different vertical stresses are studied.The results show that the axial swelling strain of mudstone decreases with increase of the vertical stress.At low vertical stresses,moisture absorption in mudstone leads to formation of cracks caused by hydration-induced expansion.Under high vertical stresses,a muddy sealing zone forms on the mudstone surface,preventing further water infiltration.The simulation results of mudstone swelling deformation also demonstrate that it involves both swelling of the mudstone matrix and swelling caused by crack expansion.Notably,crack expansion plays a dominant role in mudstone swelling.With increasing vertical stress,the cracks in mudstone change from tensile cracks to shear cracks,resulting in a significant reduction in the total number of cracks.While the evolution of mudstone kinetic energy shows similarities under different vertical stresses,the evolution of strain energy varies significantly due to the presence of different types of cracks in the mudstone.The findings provide a theoretical basis for understanding the hygroscopic swelling deformation mechanism of red-bed mudstone at various depths.
文摘A Danxia landform is a red-bed landform characterized by steep cliffs. It was initially discovered and named by Chinese scholars. Although there are red-bed landforms in many parts of the world, China, with a special fondness for the color red, boasts the most widely distributed Danxia possessing unique characteristics. This is a mesmerizing natural formation and a special gift that nature has bestowed upon this country.
