scholarly journals Soil water characteristic curve of a compacted A-7-5 tropical red earth soil

2021 ◽  
Vol 40 (3) ◽  
pp. 379-386
Author(s):  
J.O. Okovido ◽  
E.O. Obroku

Soil water characteristic curve (SWCC) is a very important property of unsaturated soil and by extension tropical red earth soils. This is because several other important soils’ properties can be related to it. The Filter paper method was employed in the determination of the A-7-5(5) tropical red earth WCC. The gravimetric water content was utilized in the computation of the SWCC. Four models, Fredlund and Xing (1994), FX; Van Genuchten (1980), VG; Brooks and Corey (1964), BC; and Kosugi (1996), K were used to estimate the SWCCs of the soil and the minimum SSEnorm (MSSE), Average Relative Error (ARE), and R2 values were used to determine the most suitable model for predicting the SWCC. Results show that all four models can be used to predict A-7-5(5) WCC as they all had R2 value greater than 89% although BC and K models perform best with coefficient of determination of over 97%. MSSE and ARE% were also significantly low for BC and K models.

2011 ◽  
Vol 90-93 ◽  
pp. 701-706
Author(s):  
Jing Song Qian ◽  
Hang Lu

The soil-water characteristic defines the relationship between the soil suction and gravimetric water content, w, or the volumetric water content, θ, or the degree of saturation, S. It is a convenient method to predict water content in the subgrade using the curve. But in the field tests of subgrades, the compaction degree of soil became lower with time than initially designed. With the purpose of finding out effect of compaction degree on soil-water characteristic curve, a study to the SWCC (soil-water characteristic curve) of Chongming low liquid limit clay using filter paper method was carried out and is presented in this paper. Specimens of different water contents were prepared by absorbing different amount of water, in order to better simulate the process of wetting of subgrade soil. After the filter paper test, the soil-water characteristic curve was fitted with two models, and then the effect of compaction degree on the curve was analyzed. The figures show that the compaction degree of the specimen will decrease with higher water content, and from the gravimetric water content-matric suction curve, it is found that compaction degree has an effect on air-entry value and water storage capacity.


2011 ◽  
Vol 312-315 ◽  
pp. 1172-1177 ◽  
Author(s):  
A. Topa Gomes ◽  
A. Viana Da Fonseca ◽  
A. Silva Cardoso

The seepage analysis in geotechnical problems, namely in excavations, was typically performed assuming saturated conditions in the ground. It is now know that the flow in the non saturated part of the ground assumes also relevant importance and hence it is vital to characterize its behaviour. The Soil Water Characteristic Curve (SWCC) of the soil is probably the most important parameter in defining this behaviour and particularly for estimating the permeability of the soil. This paper presents the definition of the SWCC for a granite residual soil using pressure plates and the filter paper method. Based on experimental data some equations are adjusted and the results obtained are discussed. At the end of the paper some predictions of the non saturated permeability of the ground are also performed.


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