Simulation of river embankment stability : a case study on failure and remedial method at Muar River, Panchor, Johor

Abstract

The soil movement on failed slope had caused substantial failure of soldier pile wall at Muar River embankment, Panchor town, Johor. The existing retaining wall has totally collapsed during low tide period is due to insufficient embedded length of existing wall system and failure due to excessive deformation of the wall and slope sliding under backfilling surcharge and human and traffic activities. To facilitate investigating causes of the failure, a computer simulation of slope stability using SLOPE/W is performed to simulate slope condition before and after construction of the study area and to check the total displacement after the construction by using PLAXIS V8.2. The river embankment collapsed during low tide period thus, the calculated back analysis of factor of safety (FOS) is based on the different at every changes of water level.The result of simulation analysis established the fact that global soil mass had a lateral movement direction toward to installed soldier pile wall generates a combination of mobilized shear force and lateral pressure larger than the capacity or strength of the soldier pile wall. Furthermore, the simulation analysis deduces that the slope instability become greater as moisture or pore-water pressure in the slope increase or decrease in soil’s shear strength. FOS determined is 0.966 during low tide period where the existing retaining wall has totally collapsed. Therefore there are 3 options of methods to be introduced to overcome the failure which are all the options introduced show the FOS ranging from 1.378 to 1.435. The anticipated settlement is in the order of 409mm over 25 years after construction.