A new apparatus for seepage and internal erosion soil column tests in geotechnical centrifuge

Abstract

Understanding the hypergravity effect on seepage and internal erosion is the essential precondition for dam hydraulic disaster modeling using geotechnical centrifuges. Soil column testing is useful to bridge this knowledge gap, but previous attempts did not provide adequate functionality in centrifuge environments. This study develops a centrifuge-available apparatus for seepage and internal erosion soil column tests (CASIE). CASIE ensures a consistent and stable circulating water supply with no less than 34,000 ml/min at 80 g via double-bowl upstream and downstream water tanks and a vertical, multistage centrifugal pump. The hydraulic gradient can be controlled by adjusting the elevation of the upstream water tank using a servo lifting system with a vertical displacement range of 1.2 m and a maximum vertical speed of 155 mm/min. A rigid-wall permeameter is developed for multiple applications in soil column tests for seepage and internal erosion. The flowrate through the specimen can be measured using four parallel-installed oval gear flowmeters with a large measurement range of 10–10,000 ml/min. To validate the capabilities of CASIE, two suffusion (one form of internal erosion) tests were conducted at 1 g and 30 g. The results reveal that the scaling factor for the critical hydraulic gradient of 30 g to 1 g is 1/10. It is much less than the predicted value of 1, indicating that suffusion failure is more readily triggered in the hypergravity environment.