Effect of compaction under different levels of moisture on physical properties of soil and yield of sugar beet (Beta vulgaris L.) in AL-Ghab Regions

The study has shown that the apparent bulk density of soil increases with the increase of compression and moisture during press. The maximum rate of increase in depth was 0 – 20 cm that amounted 0.38g/cm3 at compression by 257.44-kilopascal and moisture average at compression by 19.03% (equal to 60% of the field capacity average of the soil) in comparison with the non-existence of compression. In addition, the size of the pores bigger than 50 microns decreased at the same above compression and above moisture in depth of zero – 20 cm by 20.20%. The size of pores bigger than 10 microns decreased by 20.65% in comparison with the non-existence of compression. While it was noted that the the maximum loss of root yield that amounted 17.52%, at compression by 257.44 kilopascal, and moisture 19.03%.

Experimental Study of Subgrade Soil Reaction by Oedometer Test

The subgrade soil reaction can be determined by several experimental methods, in site and in laboratory. In this paper, the value of subgrade soil reaction Ks was measured and calculated by using the oedometer test. In addition, the variations of Ks in function of void ratio, applied pressure and time were studied. Three types of normal consolidated clay soil were tested by using odeometer test. The results show that the variation of subgrade soil reaction in function of void ratio decreases at the beginning of the test until a determined value, and then this value increases continuously. This phenomenon can be explained by the fact that while the applied pressure are near the cohesion strength of the soil, the deformation will be negligible and the value of Ks is very high, then it decreases until a determined value, and after that this value increases continuously because the sample can not be deformed any more in the oedometer cell. The value of subgrade soil reaction is variable in function of void ratio, applied pressure, and settlement and it decreases in function of plasticity. For an applied pressure, the value of subgrade soil reaction varies in function of time, where it takes a very high value at the beginning of loading, and then it decreases gradually in function of time until it stabilizes at the end of the test.