نشریه زمین شناسی محیط زیست
پیاپی 3 (پاییز 1386)

The longwall mining method is one of the best methods for exploitation of undergroundhorizontal to near horizontal coal layers. The high production and safety are the typicaladvantages. Entries of both sides longwall panel having important role in product andsafety. With increasing depth of mine, difficulty of supporting condition of entries increases.One of the basic solutions for such entries stability, particularly at deep mines, is to use yield chain pillars. Since, the behavior of coal pillar at post-peak regime is not known, so th logical designing of these yield chain pillars are not well established.In this paper, two strain-softening models with numerical and analytical fundamentals areanalyzed. These models are studied for a row of yield chain pillar at longwall mining systemat 700 m dept of surface ground. In this study, only development phase of longwall mining system is contemplated while the deformation, yielding and failure possibility are considered before longwall operation runs. Results show in deep longwall mine yield chain pillar can be used. In addition, both analyzed strain-softening models, having required potential for rather optimum understanding of pillar yielding behavior. Therefore, could be a base for yield pillar logical design. Study development shows this approached yield pillar design is sensitive to pillar behavior after coal peak strength. In addition, due to two-dimensional modeling, front abutment load influence could not be evaluated.

Mining methods are mainly depending on physical and geometrical structure of ore bodies.Room & pillar mining is very important in underground mining methods. Because of it issimplicity, high production and low cost of operations. Room & pillar method includes someintersecting tunnels in ore body, for stability of these tunnels, some parts of ore body must remain in the form of columns or so called pillar. Designing of the pillars is very important for increasing of the performance and decreasing of ore loss. Hence many empirical formulae are presented for designing of the pillars, but based on limited data. In fact, the particular restriction of each formula limits its application in various conditions and ore bodies. In this paper a new method is suggested for determination of optimum pillars design in various conditions by numerical modeling and ground reaction curve. By this method all of rock mass geomechanical and geometrical characteristics can be considered for designing of the pillars. This new method is based on ground reaction curve by making 18 models in 30, 40 and 50 meters depth with different width to height ratio (W/h) of the pillar. Each of the resulted curves in linear part which states the elastic behavior of rock mass determines the desirable width to height ratio (W/h). An Underground salt rock mine (Soltan abad’s mine) was selected for validating of the suggested method. The W/h for stable pillars in the mine is between 1.3 and 1.6. The result obtained of ground reaction curves is 1.375 for W/h which showing the accuracy of suggested method.

Jahrom Sangshekanan cave is located in fars province, in a region which is incorrugated Zagros (outer Zagros) with respect to Iran structural and geologicalunit. This cave is one of the rarest quarries which has been excavated by localpeople in recent two or three centuries. The excavation has been made by simplehand tools in order to extract dolomite limestone and use it as constructionmaterials. The internal area of the cave is about 20000 square meters. Approximatelength, width and internal height of the cave vary from 300 to 400 m, 20-100 m and3.5 m respectively. Fractures, fissure and cracks of the cave roof and internalcolumns have formed masses of potentially unstable blocks. The purpose of thispaper is study of the cave stability that is considered to develop local touristattractions. Field geotechnical investigations of the cave include twenty boreholesdrilled in a depth of 10 to 30 meters in the roof, columns and floor. According tosurveying performed, topographical and plane drawing of roof, floor and locationof columns and primary fissures have been determined. In the paper according tothe field studies of rock cores and performing suitable laboratory rock mechanicstests the properties of rock masses have been evaluated. According to the studies,stable, unstable, potentially unstable regions in roof, columns and highlydestruction regions have been specified. Finally, the optimum methods of stabilizingof the cave, regarding the characteristics of rock masses and columns, and thelocation of fissures and cracks have been presented.

Waste control and its adequate disposal are included as a substantial problem in humanlife in this world. So far vast studies have been carried out at in this regards, and several ofself healing methods have been common in practice. Since recovery of waste is not costeffective and is with the technologic limitations, with respect to the mentioned reasons, the waste Land fill is a general solution. However, practically it is impossible to give or achieve a general solution. An adequate Land fill is a place for waste Land fill which must be a location that don’t infect the environment in short term or long term. The most important problem is use of a method that doesnt let to waste emulsion to leak into the ground or to control it properly. In this research for decrease of leakage of emulsion waste, two basic specifications that are less cracking and more self healing for determination of the efficiency of soils application was analyzed. In this reason chemical, mechanical and permeability test based on ASTM standard was perform on the Kahrizak Landfill soil samples, and finally with respect to the obtained results from various cycles of drying and saturation, the permeability coefficient was calculated. Permeability coefficients in the end of 1st & 2nd cycles of drying and saturation divided by initial permeability coefficient and also the relative permeability was included as the criteria of soil efficiency for application in impermeable layers. And whatever the relative permeability of soil close to the 1, then this type of soil is ideal for using in this field also it was found that soils with less plasticity index have lesser cracks during drying.

In this research, ground motion analysis and site effect were conducted in the north ofYazd city using data from boreholes and accelerographs with regard to changes infrequency. To estimate the soil non-elastic response and equivalent linear behavior ofsoil, an iterative loop was utilized. The first iteration was performed using shearmodulus and attenuation ratio with regard to the incoming stress-strain curves. Thetest was frequently repeated in order to comply with the determined numericalrequirement. Vibrations with the most critical resonance response were assumed asthe highest probable damage mode in the area. To evaluate site effect in the northregion of Yazd city, geotechnical data, down hole seismic profiles and historicalseismic records of the region were used. The acceleration records of ground motion inbedrock for a 100 years return period in Shahediyeh and Amirabad boreholes thatare used for this resarch work are 0.151g and 0.157g, respectively. Taking the abovementioned return period into consideration, for Shahediyeh borehole the vaiues ofresonance frequency and alluvium resonance ratio were measured as 5.4 and 1.6,respectively. Similarly, for Amirabad borehole, these values are 5.8 and 1.7,respectively. On the basis of average resonance ratios and frequencies obtained fromall the models, the amplification of shear waves are intensified in frequencies between5 to 6 Hz with a resonance ratio of 1.6.

Karkheh earth Dam is located in 25 Km of south of Andimeshk. Because of hugevolume of used aggregate in spillway concrete, its investigation is necessary, in thisinvestigation, the Geology, Geomorphology, Lithostratigraphy and structuralgeology has been considered. Also grain size distribution and classification of age,and their physical and chemical properties and Los angles test are recognized.Regarding to XRF analysis results. The percentage of quartz and calcite areconsiderable which their alkali- reaction studies are important.

Aliabad Area is situated in north of Iran and contain few unimportant exploitativemineral deposits. As this area covered under jungle, thus for discovery of mineraldeposits, the stream sediment exploration method is selected. Topologic densitymethod is designed to collected 639 samples at <80 mesh size. These samplesprepared and analyzed in geological survey of Iran. The accuracy of analysesresults is conformed by paired samples controlling method. Univariable andmultivariable statistical parameters determined relatin between elements and KMeanCluster help us to ignored affect of syngenetic component related touppermost stream sediment rocks. The anomaly maps of elements drown withSurfer 8 software by using Class Post Map method. Based on associatedparagenetic elements, tectonically structures and ore bearing igneous rocks upperside of samples grid, introducinf 20 promising area, all near Alestan and NekarmanValleys, contain Cu, Pb and Zn Anomalies.

Some plant species named hyper accumulator plants have necessary potential to absorb, tolerate, remove and extract a large amount of heavy metals from the soil. Use of this plant is an appropriate commercial technology to clean up of contaminated soils. Some grass plants with deep roots, have more potential to remove soil heavy metals. Alfalfa from leguminous family which is an indigenous plant in all warm and cold weather conditions of Iran, with deep roots and short growth period, is specific plant to remove more pollutants from the polluted soils. In this paper, we tried to determine the differentconcentration of Zinc and Cadmium in soil, with use of Alfalfa plant and also discuss its bioaccessibility, then compare them with pH soil. Subsequently the effect of pH on adsorption of metals was studied. Four soil pots were artificially contaminated with 100 ppm, 200 ppm, 400ppm Zn and 500ppm, 1000ppm, 2000 ppm Cd and Alfalfa plant was cultivated in all of them. Later, agronomic practices have done on these processes to determine the effective parameters such as pH with statistical methods such as cluster analysis and MVSP software. As a result, analysis of plant, soil and its bioaccessibility reveal that alfalfa has special potential to extract both Zn and Cd together in the same manner. Cadmium concentration in alfalfa and soil were significantly increased with decrease in pH values. In pot sample number four with more pollutant, zinc and cadmium concentration increase in pH=6.72 up to 1161.75 mg/kg in plant, 58.2 mg/kg in soil and also Zinc concentration up to 3933.54 mg/kg in plant and 2703.2 mg/kg in soil. Results suggest that Alfalfa plant is a suitable plant to remove Zinc and Cadmium from the soil that is polluted. Main soil chemistry characteristics such as pH, Cation Exchange Capacity (CEC) and organic matters are more important in absorption. Results show that soil pH decrease with increase of organic matter in pollutedsoils.