Fabric characteristics of in situ sand with/without liquefaction verified by anisotropy of magnetic susceptibility

Abstract

It is well known that fabric of sand may significantly affect mechanical behaviors and liquefaction resistance of sand. Various optical techniques are currently utilized to visualize the fabric, especially the distribution of the long axis of soil particles. However, none of these methods provides an ideal solution in laboratory tests and in situ observation. In this study, anisotropy of magnetic susceptibility (AMS) was first proposed as a convenient and efficient way to evaluate the liquefaction of clean sand. At first, investigations with scanning electron microscopy (SEM) and AMS were simultaneously conducted on two groups of soil specimens with different initial fabrics to verify the feasibility of the AMS technique. Then, 80 in situ samples were collected to analyze the feature of liquefied and non-liquefied sand layers through AMS tests. It is clearly known from the test results that the natural sedimentary fabric was destroyed during liquefaction and the fabric anisotropy was greatly changed after liquefaction. The feasibility of evaluating soil fabric using the AMS survey was verified by the laboratory tests. Furthermore, the applicability of AMS in detecting liquefied layer in situ was confirmed for the first time.

Keywords

• Sand liquefaction
• Soil fabric
• Anisotropy of magnetic susceptibility (AMS)
• Geotechnical seismic engineering