Analysis of rock fall and its risk assessment by evolutionary method in rock slopes (Case study: Esfidan village, southeast of Bojnourd city, North Khorasan)

Esfidan village is one of the historical and tourist areas in 45 km southeast of Bojnourd in North Khorasan, which is located in a mountainous area. The rock falls in this area can lead to the closure of the village communication road and also damage to part of the village houses. In this paper, the possible occurrence of rock fall is analyzed by software and also the risk of rock fall in it is evaluated. Field investigations have shown that rock falls in this area are mostly due to the tectonics of rock units, the presence of discontinuities, seasonal precipitation or a combination of these factors. Jointing studies have shown that the main discontinuities in the rock slope consist of three sets of joints with two major layers. Also, sampling of rock layers and performing various physico-mechanical tests indicated that the rock layers are mainly made of high-strength limestone. Software analysis of rock fall in this slope was performed on two selected sections by Rock fall software. Then, by combining the data obtained from the software analysis of rock fall and also the field data collected from the status of the slope activity, using evolutionary method, the potential of rock fall in two selected sections was evaluated. The results showed that the slope is in the middle to high risk category in terms of the risk of rock fall and needs to implement protective measures to prevent damage to roads and residential houses.