Hydraulic characteristics of gypseous sand soil using modeled oedometer cell

Abstract

The current study investigates the permeability of the sand soil using a modified Odometer cell with a constant head connected to a data logger and computer software. The soil sample is taken from the Al-Jameah district in Al-Najaf city, Iraq. The soil is classified as “SP” according to the unified soil classification system, with a gypsum content of 29%. A modified Oedometer with computerized water volume change is adopted. The samples are disturbed and remolded into the Odometer cell with different densities of 90% and 95% of the maximum Proctor dry density and initially dry. Each of the specific density samples is subjected to three different water heads: 80, 100, and 120 cm. The first head (80cm) is applied to the initially dry soil up to a saturated and steady state. While the other heads are subjected after the completion of the first one. The results of the modification are verified with the results in the literature and it is more flexible and accurate due to the digital recording of the data by the Linear Variable Differential Transformer (LVDT). The results of the water volume change versus time and the coefficient of permeability state that the dry condition (first head) of the specimen is the longest duration of the test for both 90% and 95% density in the change from dry to saturated and then to steady condition. For a 95% density longer than the 90% as expected, but after completing the saturation by the first head, there are method results of the 90% and 95% density, and this may be attributed to the higher water head and/or the effect of the gypsum dissolution.