Iranian Journal of Earth Sciences
Volume:15 Issue: 4, Oct 2023

In the past, the fuzzy evaluation model of slope stability is mainly two-level model, and the classification level is relatively single, which cannot map the influencing factors of slope disaster comprehensively and objectively. In order to improve the accuracy of evaluation results, a three-level fuzzy hierarchy evaluation model for slope hazard is proposed. A total of 22 factors affecting slope stability in 4 categories and 9 sub-categories were selected to constitute the basic evaluation system. Taking the highway slope of the multi-line connecting line as an example, the weight was determined by AHP method, and the weight was adjusted by the back analysis of the typical highway slope. Finally, the stability of other highway slopes in the study area is evaluated on the spot, and use the information concentration formula to check, then the susceptibility level prediction of slope disasters in the whole section is realized based on GIS platform. The analysis results show that among the 77 highway slopes studied, unstable slopes account for 7.8% of the total slopes, less stable slopes account for 22.1%, quasi steady slopes account for 42.8% and steady slopes account for 27.3%. Therefore, the disaster prone zoning of highway slopes along the connecting line of Chengdu Mianyang double track line is obtained. In fuzzy comprehensive evaluation, information set formula can be used to modify the evaluation results to a more extent. In this study,compared with the second-level model, the accuracy of the three-level model improved by about 16.7%.

Mine development is the process of constructing a mining facility and supporting infrastructure. In the mining industry, operations are sequential. It means one function cannot start until its preceding operation has been completed. Hence, a delay in any operations results in an overall delay for the total target. Effective underground mine planning aims at least idle & breakdown time. One such delay examined here is the cycle time for the developments in headings and drives. In this study, Blast-to-blast cycle time was evaluated in terms of productive and unproductive work in Indian underground metal mines. The actual Average Cycle Time for blast-to-blast operations was observed at 37.12 hrs, higher than the expected Cycle Time, i.e., 12.16 hrs. The variation in cycle time leads to the delay. Therefore, a study was carried out to determine the actual cause of delay through real-time analysis of all the operations during the development. The delays were breakdown, manpower idle time, shift problem, poor ventilation, water pressure problem, etc. reduced work time utilization, dewatering, and pump breakdown were observed as significant factors for cycle time delays. Effective measures were suggested to optimize the cycle time by controlling the factors responsible for the delay and improving the development cycle.

Understanding seismic sources in a region help us to identify the level of ground motion. The area around Khalkhal city in the south of Ardabil province, northwest Iran, is a seismic region that is specially, complex from a geodynamic and tectonic point of view. Prevailing tectonic regimes in different geologic time intervals have caused at least two deformation episodes recorded by faults, folds and other tectonic structures. These structures indicate that the dominant tectonic regimes have been compressive. Examination of the seismic power of currently active faults and software analysis of their focal mechanisms, show that major activity in the region is due to faults with trend north-south and northeast-southwest. The results of this study indicate the seismic capacity of the region and the likely occurrence of earthquakes with a magnitude greater than two on the Richter scale. Also, they show that the probability of earthquakes with magnitudes above 5.3 on the Richter scale is one in one hundred years. High a- and b-values indicate the frequency of earthquakes with low magnitude and the generally high seismicity in the region.

Eocene volcanic are exposed in southeast of Zanjan in the Tarom magmatic zone that located in the Central Iran structural zone. The Abhar Eosen pyroclastic with andesite, trachy-andesite, dacite and rhyolite along with tuff compositions is located 120 km southeast of Zanjan. Mineralogically point of view, the studied volcanic rocks have low quartz, negligible alkaline feldspar, abundant plagioclase, and pyroxene contents. Textureally, Porphyritic, microlithic porphyritic, glomeroporphyritic, and poikilitic are predominant in these rocks. All of the studied samples display REE patterns characterized by LREE-enriched (Rb and Ba) and HREE-depleted segments typical of arc lavas which is one of the characteristics of subduction zone. The geochemical characteristics of the studied samples indicated that fractional crystallization is the primary cause of the diversity and differentiation of these rocks compared to crustal contamination. The rocks of the study area are composed of a similar origin to the OIB (mantle components) and partial melting of subcontinental lithospheric mantles. Of course, this mantle source has been modified by recycled sediments and melt released from the edge of the subducting oceanic crust.

Magnetite-apatite mineralization in Tarom Mountains at the western part of Alborz-Azerbaijan belt originated from quartz monzonite magma and belongs to high K calc-alkaline, showing a post-collision tectonic environment. The negative trend from LREEs to HREEs is consistent with the spider pattern of the subduction areas. In this article, the recovery of the rare-earth elements (REEs) from apatite flotation concentrate by acid leaching and digestion-water leaching were studied. The total amount of LREEs in the tailings sample is between 1500 - 2600 ppm. The most frequent elements are Ce, La, Nd, and Y. Among them Ce is the most abundant and La is the least.. The maximum LREEs recovery with the sulfuric acid leaching was62% with experimental parameters of 12 M acid concentration, 4 h leaching time, 25℃ heat, and a liquid to solid ratio (L/S) of 1:5. under optimal parameters of (220℃), (3 h), and L/S (1:2), the digesting with sulfuric acid resulted to the recovery of La, Ce, Nd, and Y with  93.92%, 92.22%, 92.04%, and 91.00%, respectively. similarity, the best conditions at water leaching process, are the leaching time of 5 h, at 80℃, and L/S of 1:10 for La, Ce, Nd, and Y recovery are respectively 89.50%, 88.45%, 92.20%, and 94.0%.

Investigating the fossil-bearing horizons of the Kond Formation in the Saran area resulted in the identification of Sardinellasardinites (Heckel 1850) belonging to the family of Clupeidae Bonaparte (1831) for the first time the east of Tehran province. Furthermore, biostratigraphic analyses based on the presence of benthic and planktonic foraminifera in this area demonstrate that the sedimentary sequence including strata of conglomerate, tuff, shale, gypsum, limestone, and marl with a thickness of 376 m in the Saran area belongs to the Priabonian, which is discontinuously located on Middle Eocene green tuffaceousshales. In the present study, 18 species belonging to 9 genera from the benthic foraminifera were identified. In the late Middle Eocene, the performance of the orogenic Pyrenean phase led to the rising of the sedimentary strata and subsequent retreat of the sea and then the sea re-advanced during the Priabonian stage. The presence of a conglomerate at the base of the formation reveals the next activity of the tectonic phase. In this study, the rock unit of the Lower Red Formation belonging to the Oligo-Miocene is located on the deposits of the Kond Formation.