Characterization of Erodibility Using Soil Strength and Stress-Strain Indices for Soils in Some Selected Sites in Imo State

C. C. Egwuonwu ； N. A. A. Okereke

《Research Journal of Environmental and Earth Sciences》 4卷7期 (2012/07) Pp. 688-696

並列摘要

In this study, initial soil strength indices (q_(u)) and stress-strain characteristics namely failure strain (ε_(f)); area under the stress-strain curve up to failure (I_(s)) and stress-strain modulus between no load and failure (E_(s)) were investigated as potential indicators for characterizing the erosion resistance of two compacted soils namely Sandy Clay Loam (SCL) and Clay Loam (CL) in some selected sites in Imo State, Nigeria. The unconfined compressive strength (used in obtaining strength indices) and stress-strain measurements were obtained as a function of moisture content in percentage (mc %) and dry density (γ_(d)). Test were conducted over a range of 8 to 30% moI_(s)ture content and 1.0 to 2.0 g/cm3 dry density at applied loads of 20, 40, 80, 160 and 320 kPa. Based on the results, it was found out that initial soil strength alone was not a good indicator of erosion resistance. For instance in the comparison of exponents of mc % and γ_(d) for jet index or erosion resistance index (J_(i)) and the strength measurements, q_(u) and E_(s) (Table 1) agree in signs for mc %, but are opposite in signs for γ_(d). Therefore there is an inconsistency in exponents making it difficult to develop a relationship between the strength parameters and J_(i) for this data set. In contrast, the exponents of mc % and γ_(d) for J_(i) and ε_(f) and I_(s) are opposite in signs (Table 1), there is potential for an inverse relationship. The measured stress-strain characteristics however, appeared to have potential in providing useful information on erosion resistance. The models developed for the prediction of the extent or the susceptibility of soils to erosion and subjected to sensitivity test on some selected sites as shown in Table 2 achieved over 90% efficiency in their functions.

並列關鍵字

Characterization ； erodibility ； Imo state ； indices ； Nigeria ； selected sites ； soil strength ； soils ； stress-strain