Abstract:
The severe flooding in 1987 and 1988 led to the design and construction of about 30 kIn long
flood control embankment on the Western side of Dhaka city. In some of the stretches, the
embankment crossed silted up channels consisting of soft subsoils. Approximately 13 kIn of
the embankment suffered some sort of failure immediately after construction, including slip
fui1ures and fuilure due to plastic lateral spread of the subsoils. Subsequent studies by local
and foreign Consultants identified several failure zones. Based on those studies three locations
ofthe embankment at Mirpur and two locations at Kellar Mohr site have been selected for this
study. Detailed field and laboratory investigations were carried out. Based on the results of
soil investigations, stability analysis using XST ABL at five critical sections (9500, 9900,
13925, 29930, 30000) of the embankment were performed compared with previous analysis.
It has been found that stability of the embankment increased significantly within the last few
years. This can be attributed to the fact that repeated dumping of soil at the top of the
embankment and consequent settlement of the embankment has improved the properties of
soil. The settlement analysis has performed for three critical sections (9900, 13925, 29930) of
the embankment. The analysis is based on the soil parameters obtained during the
construction phase of the embankment. Finite Element program CRISP has been used for
modeling settlement of the embankment. Consolidation analysis with elastic-anisotropic
model has been used. The loading is due to the self-weight of the body of the embankment.
Loading has been transferred on the foundation of the embankment in three stages using
remove-add mechanism of CRISP, to simulate embankment construction sequence. Maximum
settlement estimated for the embankment top at 9900, 13925 and 29930 are 4.07 ft, 5.44 ft
and 3.49 ft respectively.
