مجله زمین شناسی مهندسی
سال هفدهم شماره 1 (بهار 1402)

The ratios of elastic shear stiffness anisotropy and fabric anisotropy in granular soils are of very important characteristics in soil mechanics, which can influence directly lots of geotechnical engineering attributes. The shear stiffness anisotropy in a soil mass is directly related to the soil fabric anisotropy, which in turn has a fundamental contribution in variations model of shear stiffness anisotropy ratio. The main objective of this study is to evaluate the variations ranges of shear stiffness and fabric anisotropy ratios in granular soils by developing a novel approach for estimating fabric anisotropy ratio from soil grading and particles shape properties. By presuming cross-anisotropy, the anisotropic shear stiffness values of 1042 conducted tests on 200 distinct sandy and gravelly soil specimens from 43 various soil types of diverse sites throughout the world were acquired from literature. Those were then integrated with their associated void ratios, stress conditions, grading parameters and particles shape specifications to produce a comprehensive database of anisotropic shear moduli with respect to testing conditions. The collected data were analyzed, from which the shear stiffness and fabric anisotropy ratios could be calculated for examined geomaterials. The resulting values for fabric anisotropy ratio were then depicted versus grading and particles shape information to inspect the level of dependences through deriving the respective correlations. The findings of this study may serve as a suitable technique to obtain first-order approximations for fabric and shear stiffness anisotropies from soil grading and particles shape characteristics.

Waste management is a cornerstone of societal needs. The volume and composition of waste dictate the available disposal options, with landfill being a primary method. The selection of landfill sites is critically dependent on site characteristics and requires thorough and ongoing evaluation, particularly in the areas of water and soil contamination. This study started with geoelectrical and geochemical investigations in the vicinity of the landfill in the city of Damavand. It included 24 geoelectric soundings using the Schlumberger array, organized into 4 profiles covering three intervals. In parallel, three water samples, five soil samples and one leachate sample from two intervals were collected for laboratory analysis. Analyses revealed soil contamination at the waste accumulation site to a depth of two meters with a southerly extent. In particular, a cementitious layer prevents leachate from penetrating deeper into the soil. This, together with a very deep groundwater table, ensures that groundwater contamination is currently and in the foreseeable future prevented. Additional factors such as the depth of the groundwater table, the thickness of the unsaturated zone, the short life of the landfill, reduced rainfall and increased evaporation limit the volume of leachate. The pH of the leachate tends to be alkaline during dry periods and acidic during wet periods. Currently, parameters such as EC, TDS and various ionic and metallic concentrations remain within acceptable limits, ensuring minimal environmental impact.

In the present study, productivity was determined as one of the most important evaluation criteria for the building stone to cut the different faces of travertine using the diamond wire cutting method. For this purpose, measurements were carried out in two zones named 8E and 8W in the northern region of Mahallat, Hajiabad travertine located in the Markazi Province. These zones were selected because of their greater similarity in terms of geological conditions, physical and mechanical properties of the stone, quarrying facilities, machinery and equipment. In order to achieve the objective, structural studies as joint study were first carried out as a joint study through field observations of fractures, drawing rose diagrams and analyzing them. Then, the productivity of electro deposited type diamond wire cutting was measured on seven blocks in two cutting panels of the 8E zone and 13 blocks in three cutting panels of the 8W zone over a period of 45 working days was measured. The results of the research indicate that the average productivities are 7.09 and 5.71 square meters per hour for the 8E and 8W zones, respectively and the overall average value for the 8E and 8W zones is 6.4 square meters per hour. Based on these results, although the average productivity level in these zones is acceptable, but well below the ideal level (18 square meters per hour). Therefore, the productivity in this area needs to be increased.

The Evan plain is located in the Khuzestan province in the southwest of Andimshek city. Groundwater is one of the available water resources for irrigation, drinking, and industry in this region. Due to the importance of examining the ground water quality of the Evan plain, hydrochemical parameters and nitrate pollution have been evaluated. Nitrate is one of the most widespread pollutants of ground water in the world. However, few studies have been conducted on this pollutant in the Evan plain. Therefore, to assess the quality of ground water in this area with emphasis on nitrate pollution, sampling was carried out in September of the water year (1400-1401) from 22 wells in this plain. During the sampling, field parameters (temperature, pH, EC), concentrations of major elements (Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO32-, CO32-), and nitrate were measured. The results of the factor analysis demonstrated three influencing factors, namely EC, Na+, K+, Mg2+, Ca2+, Cl-, SO42-  (as the first factor), pH and Hco32- (as the second factor), and NO3- (as the third factor), with a total of 89.72% having the most changes in the Evan plain aquifer. The dominant water type in the Evan plain is sulfate-calcite. Hierarchical clustering analysis shows the three clusters for the regionalization of nitrate data. In general, the changes in nitrate ion concentration in the groundwater of the Evan plain are affected by the size of the soil particles, the depth of the groundwater, and the utilization of chemical fertilizers in the area.

The study area is a part of the Dez River Basin, which is located in the central part of the basin. In this area, due to the climatic conditions, the irregular availability in terms of time and space, the increasing use of water resources and surface water resources, there is a great dependence on the underground water of the region. The main objective of this research is to investigate the factors influencing  the fluctuations of the water level in the Dezful-Andimeshk plain during a statistical period of 20 years. For this purpose, using piezometric well level data and well logs of the study area in WinLog software, maps of the groundwater level and the bottom level of reservoir were prepared using theIDW method. The results of the research showed that the greatest drawdown occurred in north-eastern, south-eastern and western parts of the study area. Asthe amount of precipitation, evaporation and temperature are high in this part, one of the reasons for the decline in these parts can be attributed to the climatic factors of the region. Other factors in the decline of the reservoir level are the main river channel and the high slope of the area. Comparing the changes in the reservoir level with the flow of the Dez River showed that there is a high correlation between the changes in these two parameters with a time interval of one year. Therefore, according to agricultural activities, these limited resources should be harvested, scientifically and fundamentally, the region will be at risk of a serious water crisis in the future.

Ultrasonic wave velocity testing is a non-destructive, economical, simple and rapid method used for determining the physical and engineering properties of rock. This test is based on the velocity of the elastic wave in rocks. The ultrasonic wave velocity of rocks depends on intrinsic and environmental properties such as mineralogical composition, density, porosity, grain size, shape, texture, anisotropy, water content, and temperature of rocks. In this research, 10 different types of building stone, including limestone and granite, were cut into 50 cubic specimens with dimensions of 10Í4Î4 cm, and then they were tested using the Pandit wave velocity testing machine to find the effective parameters on the velocity of the ultrasonic wave should be investigated in them. These parameters include dry unit weight, temperature, type of pore fluid, state of filling material and loading. Based on the obtained results, the correlation between ultrasonic wave velocity and dry unit weight is a direct linear relationship and its relationship with the type of pore fluid condition of the filling material and loading is inverse relationship. In addition, increasing the temperature increases the velocity of the ultrasonic wave. Also, in terms of the type of pore fluid, the lowest value of the wave velocity was obtained in the state saturated with water and the highest value of the wave velocity was obtained in the common salt solution with a concentration of 150%. Regarding the state of the rock pore filling material, the highest velocity value was observed in the frozen filling state and the lowest velocity value was observed in the air filling state. As the load increases, the velocity of the ultrasonic waves decreases in the studied rocks.