STATISTICAL ESTIMATION OF THE COMPRESSIBITY OF BAGHDAD COHESIVE SOIL

Because of the time and expense involved in performing consolidation tests, it is often desirable to obtain approximate values of (C, and C,) by using other soil properties which are more easily determined. The literature contains numerous equations linking soil compressibility to its physical and index properlies. As these equations are often used to obtain preliminary evaluations of (C) and (C,), it is important to know the reliability of these equations. In this paper an attempt was made to estimate (C, and C.) of Baghdad cohesive soil from other soil properties. A number of commonly used empirical correlation equations that have been developed during the last six decades to estimate (C, and C,) were compiled and evaluated. The results of routine laboratory tests of a large number of databases of Baghdad soil were correlated with more sophisticated laboratory consolidation results by conducting simple and multiple regression analyses. It was concluded that the compression index of Baghdad cohesive soil cannot be estimated from Atterberg limits and the better values of compression and recompression indices of Baghdad soil can be obtained when more than one index property is used in the regression analysis

TREATMENT OF COLLAPSIBILITY OF GYPSEOUS SOIL

A series of double odometer tests are conducted to study the compressibility and collapse of gypseous soil taken from west of Baghdad governorate. The gypsum content of the soil used is nearly 25%. Four different types of additives are selected to reduce the collapse strain of this soil. These additives are cement, bentonite, calicium chloride and silicagel. An adequate reducing in the compressibility and collapsibility was obtained especially when the cement is used

California Bearing Ratio of Some Iraqi Dune Soils

   This paper contains the results of CBR tests that performed on compacted samples of real dune sand (cohesionless sand grains) and pseudo dune sand which is a mixture of sand sized  aggregate of  clay and silt. The effect of compaction and soaking on the bearing values are included in this research.    The results indicated that the compacted real dune sands have high strength and low sensitivity to soaking. The 5 mm penetration of CBR of this soil is higher than that of 2.5 mm. On the other hand, the loss of strength due to soaking can be quite considerable in compacted pseudo dune sands. The CBR values obtained at 2.5 mm and 5 mm penetration are approximately equal in pseudo dune sands