Analysis of Stability of Slopes at Pernem Station, Goa

Abstract

Analysis Of Stability Of Slopes At Pernem Station, Goa Statistical data reveals that more than half of the accidents that occur in the opencast work are due to the failure of the slope and the reason behind this is the improper design of the benches and insufficient work on finding the geo-technical parameters.

The most effective and simple way to cope with the slope failure is accurate determination of the overburden dump’s geo-technical parameters and then proper design of the benches using numerical modeling, water pressure simulation, Limit Equilibrium Method etc.

Cohesion and angle of internal friction are the most influential factors that contribute to enhanced slope stability. A new trend has come in the last year, i.e. using fly ash mixed with the overburden dump.

According to Environment and Forest Ministry, i.e. The guidelines of MoEF, any mine within 50 km of a power plant must use at least 25% fly ash as its backfill material. The stability of overburden dumps mixed with fly ash at SCCL’s KTK opencast mine was studied in this project.

The advantage with this is that optimum mixing of the fly ash with the dump raises the cohesion which imparts a better safety factor than the conventional method of dumping. The reason for the increase in fly ash and overburden dump mixture cohesion is that fly ash has the ability to bind the particles strongly.

Conclusion

The present study provides very useful information about the iron ore mine dump slope at Goa, India, which is very susceptible to failure. The mean safety factor of the area’s dump slope is about 1.02, which is critically stable.

The outcome of the risk assessment study reveals that for this critically stable state there are about 43 percent chances that the safety factor will be less than 1 (unsafe). It is also revealed that the margin of confidence in terms of percentage area below safety factor one decreases rapidly from 61.45 percent to 26 percent as the height of the slope increases from 25m to 50m, respectively.