CHEN Qiang, PENG Yongliang, CAO Zhengzheng, WANG Wei. 2019: EXPERIMENTAL STUDY ON DYNAMIC CHARACTERISTICS OF EXPANSIVE SOIL FROM YANZHOU-SHIJIUSUO RAILWAY ROADBED UNDER CYCLIC LOADING. JOURNAL OF ENGINEERING GEOLOGY, 27(4): 737-744. DOI: 10.13544/j.cnki.xq2019030
    Citation: CHEN Qiang, PENG Yongliang, CAO Zhengzheng, WANG Wei. 2019: EXPERIMENTAL STUDY ON DYNAMIC CHARACTERISTICS OF EXPANSIVE SOIL FROM YANZHOU-SHIJIUSUO RAILWAY ROADBED UNDER CYCLIC LOADING. JOURNAL OF ENGINEERING GEOLOGY, 27(4): 737-744. DOI: 10.13544/j.cnki.xq2019030

    EXPERIMENTAL STUDY ON DYNAMIC CHARACTERISTICS OF EXPANSIVE SOIL FROM YANZHOU-SHIJIUSUO RAILWAY ROADBED UNDER CYCLIC LOADING

    • Dynamic triaxial test was carried out on the expansive soil from Yanzhou-Shijiusuo railway roadbed. It is to study the effects of water content, vibration frequency and dynamic stress on its cumulative plastic strain, dynamic strength and critical dynamic stress. The experimental results show that when the axial cumulative strain reaches 5%as the failure standard, the relationship between the number of cycles and the cumulative plastic strain curve shows three states:stable type, critical type and destructive type. Both the dynamic strength and the critical dynamic stress decrease significantly with the increase of water content. The critical dynamic stress in saturated state is only 40kPa, which is lower than the actual dynamic load of the train. We find that critical state line exists between the critical dynamic stress and saturation and can be used to judge whether the specimen is stable, critical or failure. The vibration frequency has the following effects on the dynamic characteristics of expansive soil. When frequency equals to 0.5~2Hz, the dynamic strength increases with the increase of frequency. When the frequency continues to increase to 5Hz, the dynamic strength of expansive soil increases significantly. When frequency equals to 0.5~5Hz, the critical dynamic stress increases with the increase of frequency, which is approximately linear. The related research results are of great significance to reveal the mechanical properties of expansive soil under dynamic loading and to ensure the safe operation of railway lines in expansive soil area.
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