Abstract: In response to issues such as the low stability of traditional linear geotube embankments for dredged sludge containment, reliance on natural or artificial gullies/depressions, and low land utilization efficiency, this study proposes a novel impoundment structure composed of sand-filled annular geotubes. The pivotal scientific considerations in the design and stability analysis of this structure pertain to the pressure-bearing characteristics and strength of the annular geotubes. Utilizing a self-developed large-scale pressure test apparatus, pressure-bearing tests were conducted on a multi-layered annular geotube embankment model. The tests revealed the distribution of localized fabric tension under the combined effects of sand-fabric interface friction and inter-layer friction between the geotubes. Key findings are outlined as follows: (1) The geotextile in the pressure-bearing zone of the geotube is constrained by inter-layer friction, thereby restricting the development of its tension. Conversely, in the free zone, the geotextile tension is unevenly distributed, with the local maximum tension occurring at the interface between the pressure-bearing and free zones. (2) The modulus of the geotextile exerts minimal influence on its average tension; however, its ultimate tensile strength demonstrates a positive correlation with the pressure-bearing strength of the geotube. (3) The degree of sand fulfillment affects the development trend of geotextile tension by altering the morphological characteristics of the geotube. Based on these insights, a calculation method for determining the pressure-bearing strength of annular geotubes was developed, using the local maximum tension as the failure criterion and considering the effects of interface friction. The rationality of this method was validated through discrete element modeling.

Key words: annular geotubes, bearing capacity testing, bearing capacity, distribution of tension, discrete element modeling