نشریه زمین شناسی مهندسی ایران
سال دوم شماره 3 (پاییز و زمستان 1388)

Totally, the use of the suitable local barrow materials and the local services, are importance in civil projects. Regarding that, calcareous rocks are used extensively as barrow materials to construct of civil projects. The texture is a factor for districting the calcareous rock types. In this research, the resistance and durability of six calcareous rock samples from Hamedan province, under soundness test, were studied. The goal of this study is distinguishes the resistance texture of calcareous rocks against corrosion of chemical solutions. The results of soundness tests show that the resistance samples against corrosion have uniform texture and composition. Also, in coarse grain sizes, 37.5 to 50 mm range is durable size. Finally, the texture and grain size are an important factors on resistance and durability of calcareous rocks against corrosion of chemical solutio.

Due to its specific climatic conditions (dry climate) and severe winds (including the 120 day long winds), wind erosion is accounted as one of the most important factors responsible for earth surface changes which in turn leads to the alteration of soil engineering properties. To investigate the role of wind erosion on soil properties changes, samples were collected between the years 1385 to 1387 from four different locations including areas without vegetation in the Hamoon Lake, areas with vegetation in the Hamoon Lake, barren lands and agricultural lands without cultivation. The in situ dry unit weight volume and undrained shear strength of soil were determined by in situ tests; however, gradation, atterberg limits, and the soil maximum dry density were determined by standard laboratory tests. The results indicate a decrease in liquid limits and soil adhesiveness with time in both farming lands and clay lands without vegetation; furthermore, clay soil showed trend towards transforming into silt. Soils will become more susceptible to erodibility when their adhesiveness values decrease. In areas which the loose surface layers erode, the in situ dry unit weight volume of soil increases and reaches to 2gr/cm3 at its maximum.

Jajarm alumina mine is located in the north of Kavir in southern structural zone of Kopeh-Dagh area and Eastern section of Albourz Mountain. Because of structural setting, distinct structural’s features and major discontinuities were formed. One of the most important structural features is the Kuh-e-Zoo anticline. The axial plane of the anticline, in most part, is trending east-west. The most important formations that crops out in the area are: Mobarak (Carboniferous), Elikah (Triassic), and Shemshak (Jurassic). The topography of the region is trending northeast-southwest that is coinciding with Eastern Alborz structural setting. In order to study the instability of the mine area, data regarding the discontinuities of the layers were collected. Regarding to rock mass classification, three common classifications such as RMR, Q and GSI has been used. Base on GSI classification, the geomechanical characterizations of rock mass are determined. Finally, based on this analysis, the main agent for instability of the region is evaluated.

Granitoid and Hornblend gabroo rocks of Alvand area show a variety of engineering geological properties that may affect quarrying operation, tunneling, mining, slope stability and use of rock as construction materials. The physical and mechanical properties are functions of the mineralogical and textural characteristics of rock. The purpose of this study is to apply correlation analysis to investigate the relationship between petrographical and engineering geological properties of rocks. For this research, 90 rock samples (Granitoids and hornblend gabroo) from Alvand mountains (southwest Hamedan) were subjected to petrographic studies. The same samples were then tested to determine solid specific gravity, dry and saturated unit weight, water absorption and total porosity. Schmidt hardness, point load strength index, uniaxial compressive strength, modulus of elasticity and Linear Crack Density Index (LCDI). The relationships between these properties and the petrographic characteristics are described by simple regression analyses. The study revealed that the influence of the textural characteristics on the engineering geological properties appears to be more impotant than the mineralogy. It also determined that the type of contacts, grain (mineral) shape and size significantly influence the engineering geological properties of these rocks.

Liquefaction as a hazardous geotechnical phenomenon happens under cyclic stress of earthquake in sandy and silty saturated soils. For determining susceptible areas of liquefaction, and land use planning, liquefaction hazard maps are prepared in different scales based on the type of available data. In this study, according to manual for Zonation on seismic Geotechnical hazard (TC4), liquefaction hazard zonation for Gheshm Island in grade 2 and microzonation for Ghesham and Dargahan towns in grade 3 were conducted. Liquefaction hazard potential was assessed by preparation of representative profiles of liquefaction. The results of this study showed that, in Gheshm and Dargahan, considering the existing water table, liquefaction hazard is Low and increasing water table in Gheshm has a little effect on liquefaction potential, however increasing the water table in some part of Dargahan causes a high increase in liquefaction hazard.

Current methods for assessing quality control in constructing embankment and unbound layers are based on the determination of parameters such as field unit weight. However, most of the design methods are based on engineering properties of the materials, including their stiffness or strength values. In fact, this is a missing link between the design processing and construction quality control methods. Hence, quality control procedures should be based on criteria that are closely correlated with the performance parameters used in the design such as elastic stiffness modulus. For this purpose the use of Portable Falling Weight Deflectometer (PFWD) in the determination of earthworks layers elastic moduli is rapidly increasing The purpose of this study was to evaluate the stiffness modulus as a construction quality control criterion in unbound materials and embankments. A laboratory testing unit box was prepared in which an unbound material was compacted at different compaction levels. Then the stiffness modulus of each compacted layer was determined under Portable Falling Weight Deflectometer (PFWD). The results indicated acceptable correlations between the stiffness modulus and both compaction percentage and moisture percentage. However, it was found that the stiffness modulus is a more appropriate indicator than compaction percent in discerning the true behavior of the unbound layers.

Consideration to explosion resistant design of special infrastructures has increased in the recent years. Amongst the various types of infrastructures, road and railway tunnels have a unique importance because their vital role in connection routes in emergency conditions. In this paper, the explosion effects of a projectile impacting on a railway tunnel located in jointed rock medium was investigated using DEM in two dimensions. For this purpose the UDEC as a well known DEM code was utilized for numerical modeling of the explosion phenomenon. In this regard in first step, selecting the GP2000 bomb as a usual projectile, the penetration depth and crater diameter were calculated in rock medium. In the second step, the blast pressure was calculated via empirical formulae and applied on the boundary of carter as input load. In continue the pressure wave propagation through the jointed rock medium was investigated. In part of the study a sensitivity analysis is carried out on jointed rock parameters such as joint orientation, dynamic modulus and damping ratio and their effect on tunnel lining axial force as well as bending moment were investigated.