Steady-State Groundwater in Mechanical Stabilized Earth Walls of Various Dimensions with Geocomposite Back Drain Installation

Phreatic Surface Estimation In MSE Wall With Geocomposite Back Drainage

“…To date, engineers design the required transmissivity of drainage layer using a classical Dupuit's formular with an assumption that the phreatic level inside the protected zone is zero. Previous study from the authors (Chinkulkijniwat et al, 2016, Bui Van et al, 2017, La Duong et al, 2021 reports none zero phreatic level inside the protected zone even after assigning transmissivity of drainage layer greater than that provided by Dupuit's equation.…”

“… Based on previous report (La Duong et al, 2021), important parameters playing role to the change of ho are 1) permeability coefficient of upstream soil (k), 2) transmissivity of the back drain (Tnet), and 3) a ratio of the distance from the upstream water source to the drainage face to the wall height (L/H). Hence, the model was established based on variation of these 3 parameters.…”

“…In practical situation, the soil located in protected zone always possesses its permeability coefficient no less than that of the upstream soil. According to Bui Van et al (2017) and La Duong et al (2021), if the soil in the protected zone possesses more permeable than the soil in the upstream side does, the flow path reflection results in the lower phreatic surface in the protected for the more permeable soil in the protected zone than that for the less permeable soil in the protected zone. As such, magnitude of ho approximated from the proposed equation is conceptually no lower than that take place in MSE wall having higher soil permeability in the protected zone than that in the upstream side, i.e.…”

“…For a given wall geometry of homogeneous soil, La Duong et al (2021) reported linear relationship between ho and logarithm of geonet transmissivity (Tnet). Furthermore, the gradient of the ho-log(Tnet) relationship was found governed by the permeability coefficient of the upstream soil.…”

“…(D/H), the protected zone width to the wall height (W/H), and the distance from the upstream water source to the drainage face to the wall height (L/H), LaDuong et al (2021) reports that except the dimension ratio L/H, other wall dimension ratios play small to negligible role to the magnitude of ho/H. Accordingly, for wall dimension set up in this study, the wall height (H), distance from the wall base to the impervious boundary (D), and the protected zone width (W) were fixed at 2.0 m, 0.8 m, and 2.0 m, respectively.…”