River branches (creeks)‎ banks stability in Khor Al-Zubair Area-NW the Arabian gulf

الملخص EN

The study area is located in the middle part of Khor Al-Zubair, NW the Arabian Gulf.

Thirty-six samples were selected form six stations in the study area, six samples from each station, at depth 0.5m from ground surface.

Distances, elevations and inclinations were measured in four traverses in the study area.

The sampling and fieldwork were carried out during Oct.

2001 to March 2002.

Mud corer and hand Auger tools, and level device were used for this purpose.

The laboratory tests included direct shear test, moisture content, bulk & dry densities, consistency limits, grain size distribution and clay activity tests.

Office calculation and computer programs were used to evaluate the bank stability.

The field measurements show low inclination angle of each bank about (18.5°).

Laboratory tests results indicate moderate value of cohesion 24-37 kN/m2 with zero value of internal friction angle.

The moisture content is between 38-68 %, bulk density is 1100-1900 kg/m3 and the value of dry density varies between 700¬1200 kg/m3.

Consistency limits results show that the soils have high plasticity according to the USCS classification.

Liquid limit values are between (55-64 %) ; plastic limit and plasticity Index values are about (25-30 %) and (26-40 %) respectively.

The soils classified as Silty Clay, the sand content is less than (1 %), Silt and Clay contents value varies between (41-56 %) and (44-59 %) respectively.

Clay Activity is (0.47-0.73), which indicates that the soils are inactive clay.

The sediments appear high cohesive, the high moisture content could be related to immersing all times and also to high content of clay fraction.

The high content of fine-grained sediments conducts to rend the soil to be high plasticity, more moist, high cohesive and inorganic.

The cohesive appearance of the soil in the area and the low inclination angle decrease the failure ability of the banks.

The calculations proved that the factor of safety was more than one in each traverse, in spit of the tide phase.