Abstract
The impact of damaged sidewalls at the joints between tubes on dam structures subjected to horizontal seepage is investigated. First, an experimental scheme is designed to test the mode and critical gradient of seepage failure of the soil in the damaged tubes. The effects of various overburden pressures (0, 5, 10, 20, and 30 kPa), hole radii(0.5, 1.0, 1.5, and 2 cm) and soil specimen properties were studied. The test phenomena and the changes in the pore water pressure were used to determine the seepage failure modes and the critical gradients under different conditions. Combined with the modified Terzaghi soil arching theory, a mathematical model was developed for the critical gradient for soil seepage failure. The model fitting curve was in good agreement with the laboratory test results. The critical gradient is independent of the overburden pressure and weakly dependent on the internal friction angle of the soil. The critical gradient increases with the cohesion. For fixed characteristic soil parameters, the critical gradient decreases at a gradually decreasing rate as the radius of the damaged hole increases.
Highlights
Geotube dam construction technology offers the advantages of low environmental impact, ease of construction, low cost, and high efficiency [1,2,3,4]
The data distribution shows that for a fixed hole radius, the critical gradient does not change as the overburden pressure increases
The mechanisms for horizontal seepage failure from damage to a geotube sidewall were studied by performing laboratory tests and developing a mathematical model
Summary
Geotube dam construction technology offers the advantages of low environmental impact, ease of construction, low cost, and high efficiency [1,2,3,4]. Once a reservoir is impounded, the soil in the geotube undergoes seepage erosion under the difference in the hydraulic head between the interior and exterior of the dam[18]. Only the failure of the soil in tubes under horizontal seepage for an O-shaped hole in the seam sidewall was investigated in this study. Laboratory tests were performed to determine the horizontal seepage failure modes and critical gradients of soil in damaged geotubes under various operations conditions. A geotextile is glued to the plate to prevent soil particles in the soil-filling chamber from entering the steady-flow chamber during the test. The test results for Soils A, B, and C show internal friction angles of 35 ̊, 33 ̊, and 30 ̊, respectively, and cohesions of 0.5 kPa, 1.0 kPa, and 1.0 kPa, respectively
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