Model and Experimental Studies of the Seepage Failure of Damaged Geotextile at the Joint between Tubes in a Geotextile Tube Dam

This paper focuses on the impact of geotextile tube damage at the joints between tubes on dam structures subjected to seepage. First, a seepage-induced failure critical gradient model for damaged geotextile tubes was developed. Tests were conducted using geotextile specimens with precut O-shaped holes to simulate the seepage erosion process. Various overburden loads (0, 5, 10, 20, and 30 kPa) and hole radii (0.5, 1.0, 1.5, and 2 cm) were examined. Based on the test phenomena and the changes in pore-water pressure and seepage flow, four progression stages (seepage stability, sand particle wash-out, preferential flow formation and development, and complete failure) were identified. The experimental critical gradients obtained under different conditions agreed well with the model results. The critical gradient is positively correlated with the overburden load and negatively correlated with the hole radius. Critical gradient growth gradually slows with increasing overburden load. The critical gradient difference caused by the hole size decreases rapidly. When the overburden load increases to 20 kPa, this difference is essentially unchanged. These findings can provide a better understanding of the performance of damaged geotextile tubes.