Model tests on moisture migration based on high-density electrical resistivity tomography method

In geotechnical model tests, the methods conventionally employed in measuring water content and solute transport include sensor techniques, image processing techniques and direct soil sampling methods. However, these techniques cannot fully satisfy the necessities of three-dimensional, non-destructive and real-time measurement, especially in geotechnical centrifuge environment. A set of new measuring device and analyzing technique based on the high-density electrical tomography (ERT) method, is developed to investigate water migration at multiple gravitational levels. Two model tests, one on ground and the other in a geotechnical centrifuge, are conduced to verify the capability of the developed device in capturing moisture migration and distribution. The 3D infiltration model tests on ground (1g) show that the device is capable of measuring the 3D spatial and temporal distribution of soil resistivity in the model. The water migration and distribution during the infiltration process is reasonably reflected by the variation and distribution of soil resistivity. The resistivity method presents high sensitivity, especially when the soil is at relatively low saturation degree. In the 50g centrifugal model tests, obvious non-uniformity of water content distribution is observed at the loading and unloading stages, which indicates that moisture migration is highly subjected to gravitational levels and boundary conditions. The capability of real-time measurement and analysis of the ERT method provides critical insights into moisture migration in geotechnical model tests at multiple gravitation levels, and can be fed into a wide range of investigations regarding seepage and solute transport.