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Landslide Assessment in Baku Azerbaijan

Following a major landslide, concerning an area of some 15 ha, which occurred abruptly on March 7, 2000 in the Bayilev zone of the Sabayil district, South of Baku city center, DRM was charged by the World Bank to provide a technical assistance in order to determine the adequate remediation and prevention works to be carried out. The available information on the landslide activity in the concerned zone was reviewed on site by an expert of EPFL, in order to identify the future risks of landslides, to propose possible remedial and monitoring works and to give some advice on the use of the surrounding areas. The expert was also asked by the Vice Prime-Minister of Azerbaijan to assess the remediation works already carried out and the necessity of relocating endangered houses near the landslide.

Numerous data on the topographical, geological and geotechnical conditions could be obtained, but it was quite difficult to get information on actual damage and repair work costs, as well as on climatic and hydro geological conditions. All the gathered information was analysed in order to do extensive stability computations, so as to assess the efficiency of the various planned stabilizing actions.

The analysis of the landslide mechanism and of its causes revealed that it was a single compound slide with one slip surface in fairly unfavourable geological conditions, which was mainly triggered by very important rainfall in October and November 1999 (more than the average annual precipitation occurred in two months). Due to the low permeability of the soil, the groundwater table was slowly recharged; but the investigations after the disaster showed that the crack openings in the landslide zone had allowed a significant lowering of the water table. Some water leakage from utility lines crossing the slide may also have had a detrimental preparatory effect.

The main design adopted was to trim the whole slope that is to recreate a smooth regular ground surface from the toe to the top. But it has to be complemented by drainage and above all toe loading, rather than by building a double row of piles in the lower part of the slide as it was designed locally. Furthermore, it has been advised to develop a comprehensive monitoring program to control the safety conditions in the vicinity of the scarp and check the efficiency of the stabilizing works.

The total costs induced by the landslide appeared much smaller than the initially announced losses of 23 million US $. They can presently be assessed as less than 4 million US $, depending on the amount spent for the resettlement of evacuated persons.

Finally, some recommendations and conclusions have been expressed concerning the stabilization works, the monitoring and control of the affected zone in order to limit its use during the first five years; then it will be possible to determine if restricted planning within the damage zone may be modified.