The relationships between geo-techanical properties and cracks of vertisols in Dohuk governorate

الملخص EN

Vertisols covered vast areas in Duhok governorate, and there is no comprehensive study about geo- technical properties in it, that are closely related with cracks in vertisols, therefore is very important to study this relation, depending on the statistical analysis in order to give clear idea about these properties that are consider very important in the field of agriculture and engineering to achieve this objective this study was conducted.

Twenty seven surface and subsurface soil samples representing vertisols in Dohuk governorate (Doban, Sulaivani and Sendi plains) were obtained.

Highly calcareous study soils.

Soil physical, chemical and geo- technical properties were determined according to the standard methods.

The results are displayed for linear shrinkage in vertisols of sulaivani plain were larger than the linear shrinkage values in doban and sendi plain whereas the smallest values were found in vertisols of sendi plain.

Generally found inverse relationship between linear shrinkage values and carbonate (Total and Active) in vertisols of the study areas.

The stepwise multiple linear regression relationship established between width of crack and (Total carbonate, Sand fraction, Iron oxides and Electrical conductivity) properties.

There is a highly significant correlation between width of cracks and each of previous soil properties (Sig.

= 0.000003).

The statistical analysis results indicated that the total and active carbonate effected on the depth of cracks profoundly (r2 = 0.83) and this relationship was very high significant (Sig.

= 0.0001).

The results also showed great conformity between observed and predicted swelling percentage in vertisols of study areas.

The best fit of plasticity index with total and active clay is a second degree polynomial (r2 = 0.978).

Based on clay activity values the study soils were classified as inactive clays (A.C.

< 0.70).

Geotechnical properties analyses are indicated that the consistency index values decreased with depth in all pedons except pedon ( 9 ) and this may be due to concentrated organic matter in the surface layer of the soil and decreasing with depth.

Can be concluded the study soils exhibit high potential to swell and shrinkage and highly significant correlation of swelling percent with clay activity, active carbonate, organic matter, sand and EC.