Very high cycle fatigue（VHCF） behaviors of bridge steel（Q345） welded joints were investigated using an ultrasonic fatigue test system at room temperature with a stress ratio R = -1. The results show that the fatig...Very high cycle fatigue（VHCF） behaviors of bridge steel（Q345） welded joints were investigated using an ultrasonic fatigue test system at room temperature with a stress ratio R = -1. The results show that the fatigue strength of welded joints is dropped by an average of 60% comparing to the base metal and the fatigue failure still occurred beyond 10~7 cycles.The fatigue fracture of welded joints in the low cycle regime generally occurred at the solder while at the heat-affected zone（HAZ） in the very high cycle regime.The fatigue fracture surface was analyzed with scanning electron microscopy（SEM）,showing welding defects such as pore,micro-crack and inclusion were the main factors on decreasing the fatigue properties of welded joints.The effect of welding defects on the fatigue behaviors of welded joints was discussed in terms of experimental results and finite element simulations.展开更多
Soil consolidation would induce variations of its transport coefficients such as hydraulic conductivity and diffusion coefficient. This paper presents a study of the influence of barrier consolidation on transport coe...Soil consolidation would induce variations of its transport coefficients such as hydraulic conductivity and diffusion coefficient. This paper presents a study of the influence of barrier consolidation on transport coefficients, and a 3D transport model based on mixture theory is proposed for describing the liners that involve circular defects in the geomembrane. The elastoplastic ALPHA model is revised by using the spatially mobilized plane （SMP） criterion for simulating the deformation of the soils. Then, the 3D model coupling the nonlinear consolidation and contaminant advection-diffusion is solved using the finite element software ABAQUS. The results show that the importance of reducing the defect size in the geomembrane and the liner porosity to control the contaminant concentration increase展开更多
The release of intracellular water during degradation process contributes to the great leachate production and settlement of landfilled high kitchen waste content MSW(HKWC-MSW). An oven-drying and absorbent-paper comb...The release of intracellular water during degradation process contributes to the great leachate production and settlement of landfilled high kitchen waste content MSW(HKWC-MSW). An oven-drying and absorbent-paper combined method was proposed to measure the intracellular and interparticle water contents of HKWC-MSW. Two degradation experiments were carried out to study the release process of intracellular water and its effect on the hydro-mechanical behaviors of HKWC-MSW.It was found that the two degradation experiments showed similar degradation behaviors with BOD/COD decreasing with time in the early stage. In the first degradation experiment, most intracellular water was released during the first two months, and the degradation of degradable matter in kitchen waste(KW) was much slower than the release process of intracellular water. The particle size became smaller and the overall grain specific gravity increased during the fast release process of intracellular water.In the second degradation experiment, after two-year degradation, the total leachate production was about 45.2% of the initial wet weight of HKWC-MSW specimen. Water retention capacity θ_f increased from 0.23 to 0.58 during 1–69 d, which might be caused by the decrease of particle size and compression of waste skeleton. As almost all the intracellular water was released after 80-day degradation, during the latter stage of leachate drainage under gravity, θ_f decreased and was close to the total volumetric water content. The total compression strain was about 0.39. The secondary compression strain during 1–80 d(i.e., about 0.07)was considered to be mainly resulted by the release of intracellular water and the subsequent drainage of leachate, and it accounted for about 22.6% of the total secondary compression strain.展开更多
基金supported by the China National Funds for Distinguished Young Scientists(10925211)the National Natural Science Foundation of China(50878174)
文摘Very high cycle fatigue（VHCF） behaviors of bridge steel（Q345） welded joints were investigated using an ultrasonic fatigue test system at room temperature with a stress ratio R = -1. The results show that the fatigue strength of welded joints is dropped by an average of 60% comparing to the base metal and the fatigue failure still occurred beyond 10~7 cycles.The fatigue fracture of welded joints in the low cycle regime generally occurred at the solder while at the heat-affected zone（HAZ） in the very high cycle regime.The fatigue fracture surface was analyzed with scanning electron microscopy（SEM）,showing welding defects such as pore,micro-crack and inclusion were the main factors on decreasing the fatigue properties of welded joints.The effect of welding defects on the fatigue behaviors of welded joints was discussed in terms of experimental results and finite element simulations.
基金supported by the National Natural Science Foundation of China (50778013)the National Basic Research Program (973) of China (2010CB732100)
文摘Soil consolidation would induce variations of its transport coefficients such as hydraulic conductivity and diffusion coefficient. This paper presents a study of the influence of barrier consolidation on transport coefficients, and a 3D transport model based on mixture theory is proposed for describing the liners that involve circular defects in the geomembrane. The elastoplastic ALPHA model is revised by using the spatially mobilized plane （SMP） criterion for simulating the deformation of the soils. Then, the 3D model coupling the nonlinear consolidation and contaminant advection-diffusion is solved using the finite element software ABAQUS. The results show that the importance of reducing the defect size in the geomembrane and the liner porosity to control the contaminant concentration increase
基金supported by the National Basic Research Program of China(Grant No.2012CB719800)the National Natural Science Foundation of China(Grant Nos.51708508,41402249)the Zhejiang Provincial Natural Science Foundation(Grant Nos.LY17E080021,LY15E080021)
文摘The release of intracellular water during degradation process contributes to the great leachate production and settlement of landfilled high kitchen waste content MSW(HKWC-MSW). An oven-drying and absorbent-paper combined method was proposed to measure the intracellular and interparticle water contents of HKWC-MSW. Two degradation experiments were carried out to study the release process of intracellular water and its effect on the hydro-mechanical behaviors of HKWC-MSW.It was found that the two degradation experiments showed similar degradation behaviors with BOD/COD decreasing with time in the early stage. In the first degradation experiment, most intracellular water was released during the first two months, and the degradation of degradable matter in kitchen waste(KW) was much slower than the release process of intracellular water. The particle size became smaller and the overall grain specific gravity increased during the fast release process of intracellular water.In the second degradation experiment, after two-year degradation, the total leachate production was about 45.2% of the initial wet weight of HKWC-MSW specimen. Water retention capacity θ_f increased from 0.23 to 0.58 during 1–69 d, which might be caused by the decrease of particle size and compression of waste skeleton. As almost all the intracellular water was released after 80-day degradation, during the latter stage of leachate drainage under gravity, θ_f decreased and was close to the total volumetric water content. The total compression strain was about 0.39. The secondary compression strain during 1–80 d(i.e., about 0.07)was considered to be mainly resulted by the release of intracellular water and the subsequent drainage of leachate, and it accounted for about 22.6% of the total secondary compression strain.
