Mechanical Consequence Observation and Microscopic Visualization of Internal Erosion Using Developed Plane Strain Erosion Apparatus

Abstract

Abstract Internal erosion has been frequently reported and has caused failures and instabilities of geotechnical structures. A plane strain erosion apparatus is developed in this study to allow the subsequent conduction of drained compression test after seepage test and the microscopic observation of particle movement through a transparent window. A drained compression test preceded by a seepage test is performed on specimens containing the same initial fines contents to investigate the mechanical consequence impacts of seepage-induced internal erosion. Experimental results reveal that, compared with uneroded soils, internally eroded soils show a larger secant stiffness at a small strain level (∼1 %). At medium strain level (∼15 %), the soils with erosion show smaller deviator stress comparing with soils without erosion. The analysis of images recorded by the microscope proves that the fines contacted with coarse particles possibly transferring the load are distinct between the soils with and without internal erosion at both small and medium strain levels during the drained compression test, which indicates that the soil fabric could affect the mechanical behaviors of soils subjected to internal erosion. Our designed equipment and microscopic observation could throw some light on the research of internal erosion from the view of particle scale.