Microstructure and Hydraulic Properties of Coarse-Grained Subgrade Soil Used in High-Speed Railway at Various Compaction Degrees - Archive ouverte HAL Access content directly
Journal Articles Journal of Materials in Civil Engineering Year : 2019

Microstructure and Hydraulic Properties of Coarse-Grained Subgrade Soil Used in High-Speed Railway at Various Compaction Degrees

Shuai Qi
  • Function : Author
Yu-Jun Cui

Abstract

This study presents an experimental investigation on the microstructure and the hydraulic properties of a coarse-grained soil used in high-speed railway track bed at various compaction degrees. A large-scale infiltration column was adopted to study the soil water retention curve (SWRC) and the hydraulic conductivity. The microstructure of the fines in the samples was investigated by scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) tests. The results reveal the existence of a characteristic pore diameter as 12.1 μm, separating two pore groups: macropores (pore diameter≥12.1  μm) and micropores (pore diameter<12.1<µμm). According to the Young-Laplace law, this characteristic pore diameter is consistent with the matric suction (negative pore water pressure, the difference value between the air pressure and the water pressure) value of 24.0 kPa. This value is also the characteristic matric suction ψcha identified from the infiltration column test. When the matric suction is lower than ψcha, the hydraulic properties of this soil are primarily affected by the macropores. As the compaction degree increases, the macropore content decreases, leading to the decreases of the water retention capacity and the hydraulic conductivity in this suction range. However, with the matric suction higher than ψcha, the micropores more significantly affect the hydraulic properties. As the compaction degree increases, the micropore content increases, resulting in the increase of the water retention capacity and the hydraulic conductivity at this suction state.
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Dates and versions

hal-02499358 , version 1 (05-03-2020)

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Ren-Peng Chen, Shuai Qi, Han-Lin Wang, Yu-Jun Cui. Microstructure and Hydraulic Properties of Coarse-Grained Subgrade Soil Used in High-Speed Railway at Various Compaction Degrees. Journal of Materials in Civil Engineering, 2019, 31 (12), pp.04019301. ⟨10.1061/(ASCE)MT.1943-5533.0002972⟩. ⟨hal-02499358⟩
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