Factors Affecting Failure by Internal Erosion of Geosynthetic Clay Liners Used in Freshwater Reservoirs

Abstract

Geosynthetic clay liners (GCLs) are often used as lining materials for freshwater reservoirs. To irrigate agricultural land without depleting groundwater, surface water is stored in these artificial ponds. In this study, hydraulic conductivity tests were performed on GCLs placed in flexible-wall permeameters under hydraulic heads of up to 50 m in order to investigate the risk of internal erosion. In these tests, base pedestals made of Plexiglas with uniform circular voids were placed beneath the GCLs instead of a typical gravel subgrade. The voids in the base pedestal represented the voids between uniform rounded gravel particles. Different types of GCLs were tested. GCL-1 was reinforced using needle-punching technology, whereas GCL-2, GCL-3, and GCL-4 were un-reinforced GCLs that were assembled in the laboratory. We investigated the effects on internal erosion of the void size in the subbase; the geotextile component that was in contact with the subbase; the bentonite component; and the manufacturing process of the GCLs. Test results indicated that internal erosion was directly related to the void diameter of the base pedestal. The resistance of the needlepunched GCL to internal erosion was better than that of the un-reinforced GCLs. The degree of internal erosion was also related to the engineering properties of the geotextile in contact with the base pedestal. Higher tensile strength of the GCL reduced the possible potential for internal erosion within it. The type of bentonite did not have a significant effect on internal erosion.157

Sodium Carboxymethyl Cellulose-Enhanced GCLs in Freshwater Reservoirs

“…After each hydraulic head increase, the hydraulic pressure acting on the GCL was kept constant for a period of 12 days. This period was chosen because a sudden increase in permittivity and then, the initiation of internal erosion for the tested GCLs was obtained in almost 12 days in previous studies [2,7,10]. Hydraulic head of 30 m was maintained by taking the cell pressure, influent pressure at the top of the GCL and effluent pressure at the bottom of the GCL as 550, 530 and 235.7 kPa respectively [19].…”

“…This could be the main reason why the unconfined compressive strength of the GCLs increased due to an increase in the biopolymer content [17,24]. The results of some previous studies showed that internal erosion of the GCL was mainly related to the grain size of the subgrade soil beneath the GCL and the hydraulic load acting on the GCL [2,[5][6][7][8]. As the grain size and the hydraulic load increase, the internal erosion risk also increases.…”

“…Internal erosion of the GCL is mainly affected by the granularity of the subgrade soil over which the GCL is placed. As the grain size diameter of the subgrade soil increases, the risk for the internal erosion also increases [6,7]. Coarse-grained gravel subgrades or cover soils generally caused internal erosion for the GCLs [5][6][7][8].…”

“…As the grain size diameter of the subgrade soil increases, the risk for the internal erosion also increases [6,7]. Coarse-grained gravel subgrades or cover soils generally caused internal erosion for the GCLs [5][6][7][8].…”

Microplastic Contamination in Soils: A Review from Geotechnical Engineering View

“…Moreover, the GCLs have some advantages over the CCLs such as having lower hydraulic conductivity (<10 −10 m/s), lower thickness (4–10 mm), lower cost, less labor work and faster installation [ 72 , 77 , 78 ]. The most critical component of a GCL that determines the hydraulic performance of the barrier material is the bentonite layer [ 79 , 80 , 81 ]. A waste disposal area in Kütahya, Turkey before and after the placement of a barrier system that was composed of a geomembrane-laminated GCL is shown in Figure 4 .…”