Appraisal of Geotechnical Characteristics of Ormara Soil, Baluchistan, Pakistan

Abstract

Ormara is located 240 km west of Karachi which is a coastal and port city (25° 16' 29N, 64° 35' 10E) of
Pakistan. Present study evaluates engineering properties of soils of Ormara for future construction plans and possible
expansions in the area. Fifty bore holes were done in study area at depths of 20m, 40m and some (10 bore holes) were
60m deep. The study area was divided into three major zones i.e. Foot hills, on-shore and off-shore. Groundwater was
encountered at depths of 2.75m on onshore and offshore zones and at 3.65m depth in foothill zone. Laboratory testing
i.e. moisture content (12 to 38 %), liquid limit (from 26 to 34), plasticity index (10 to 18) of soil samples indicate that
soils are low plastic to moderate plastic in nature. Soil samples of granular soils indicate angles of internal friction (ø)
varying from 260- 36ºin upper sand layers while 260 to 30º in lower silt layers (encountered after the clay layer) and
Cohesion ranges 0 to 0.04kg/cm2 in all three zones. Further, unconsolidated undrained triaxial compression tests on a
clayey soil sample indicated an undrained cohesion value of 28 kPa. Density values ranges from 1.6 to 2.05gm/cm3.
Consolidation (Cv = 0.20 to 0.40 cm2/minute, Cc = 0.149 to 0.17) has been calculated for clay layer. Chemical tests
carried out on soil samples indicated that soil and water both are reactive aggressively and may cause corrosion to steel
and concrete disintegration.

Keywords: Ormara, geology, soils, geotechnical characteristics.