gholamreza khanlari

Assessing and understanding the hydromorphological characteristics are necessary to understand the behavior of a river and its active processes. This is useful for understanding the erosion and sedimentation regime and changing the river path, for making correct engineering and human activities in the river's catchment area. The Gian River, with an average annual discharge of 2.3 m3/s, is one of the tributaries of the Gamasiab River in the Hamedan province. From a geological and hydrogeomorphological point of view, the Gian is a small river. It is fully compatible with the geological structures of the region. The calculation of the sinusoidal coefficient has shown that this river is a meandering river whose wavelength, the amplitude of the oscillation and the width of the meander belt are smaller in the mountainous area than in the plain area The gradient of the river bed is relatively low and it is classified as an erosion and sedimentation river in its different sections. The Gian River has a rocky bed in the mountainous part and an alluvial bed in the plain. The Gian River has a small catchment area, and, according to theGravelius' coefficient, its shape is almost elongated. The catchment elevation of the Gian River is between 1455 and 2700 with a weighted average of 1715.20 m.a.s.l. and its area decreases with the increase in the elevation. The concentration time of the catchment is 4.204 hours. The application of the data and results of the research can be very effective in land use planning, engineering and executive applications to predict river changes and protect engineering structures such as roads, bridges, coastal structures and railways, protect agricultural lands in the region and develop tourism.

This study investigates the relationship between slake durability indices and geomechanical characteristics of five types of carbonate rocks situated in the west of Iran along the Doruod-Khorramabad highway. In this study, five types of limestone rocks were selected, including grey limestone (A), marly limestone (B, C, D), and sandy limestone (E). The geomechanical characteristics of the studied limestones were calculated based on the ISRM (1981) standard stimulations. Statistical approaches were executed to find the most influential geomechanical characteristics on slake durability indices and to find an appropriate slake durability cycle for interpreting rock behaviors. According to the simple regression analysis, the first and fourth cycles of slake durability can provide adequately good information for initial engineering/design works. Also, the correlation coefficients demonstrated nearly constant change after the fourth cycle. Geomechanical parameters, like Schmidt hammer and dry density, showed the highest correlation with the fourth slake durability cycle (R =0.98). On the other hand, uniaxial compressive strength revealed a poor correlation (R = 0.49) with this cycle. Apart from estimating the 4th durability cycle from geomechanical properties, it is possible to calculate the second to fourth cycles of slake durability using the results of the first durability cycle (R = 0.99–0.94). Consequently, a multivariate equation was developed based on water absorption, Schmidt hammer, effective porosity, and modulus of elasticity with R2=0.89 using the best subset regression method.

The aim of this study is analyzing the failure modes of sandstones related to Markazi Province using compressive strength changes. For this purpose, the fracture modes of five different types of sandstones with different compressive strength values have been studied experimentally and numerically. Also, The effect of failure modes on uniaxial compressive strength was quantified. block samples were collected from different sandstone formations located in northern part of Markazi province. These sandstones were divided into five types based on the textural and mineralogical characteristics. These samples were subjected to uniaxial compressive strength testing. Examination of the fracture modes showed that simple shear mode occurred at low values of strength and it changes to multiple extension mode with increasing the compressive strength. The dominant failure mode for types 1, 2 and 4 is simple shear and for types 3 and 5 is multiple extension. Investigation of failure modes in different strength ranges showed that the dominant failure modes up to 140 and over 140 MPa are simple shear and multiple extension, respectively. Therefore, strength of 140 MPa was considered as the transisson point. Also, in this study, the failure modes of the experimental samples were numerically simulated using PFC2D software. The results of numerical modeling showed a good agreement with the experimental results.

In this study, the salt weathering effects on engineering properties and weight loss potential of three types of granitoid rocks were investigated. Sodium and magnesium sulfates tests were performed on core and aggregate samples. The cyclic salt weathering tests on core samples were done up to 90 cycles, while these tests on aggregate samples were done up to 40 cycles. The results showed that deterioration effect of magnesium sulfate on weight loss was more remarkable than sodium sulfate. However, deterioration effect of sodium sulfate on weakening of physico-mechanical properties was more considerable than magnesium sulfate. Porphyroid monzogranite was far more affected by the salts in comparison with other rock types which were tested in the current study. The results showed that ultrasonic wave velocity parameter was more appropriate than other engineering parameters to demonstrate the damage processes. Finally, a crack development weathering pattern and a corrosive damage pattern were observed for sodium sulfate and magnesium sulfate respectively.

In this research, different experimental techniques have been used to determine the strength of four types of travertines, selected from Hamedan and Markazi Provinces, west and central parts of Iran respectively. For this purpose, after sample preparation and assessment of mineral properties, the selected samples were subjected to physical and mechanical tests with special reference to two major anisotropic angles (i.e. perpendicular (⊥) and parallel (∥)) between bedding/lamination planes and the major loading directions. Based on the test results, it can be concluded that the percentage/type of matrix and porosity have a more important effect on the physical and mechanical properties than the rock structure. Statistical analyses, including simple and multiple linear regressions, were applied to identify those physico-mechanical parameters that are more appropriate to predict uniaxial compressive strength (σ_(c⊥) and〖 σ〗_(c∥)) and to establish some new equations. Data analysis in simple regression shows that bulk specific gravity (saturated surface dry, SSD) and Brazilian tensile strength are the most and the least influential factors on σ_(c⊥) and〖 σ〗_(c∥), respectively. Based on multiple regression method, equations with only two parameters (a physical and a mechanical parameter) were extracted for calculating σ_(c⊥) and σ_(c∥).

Nowadays urban transportation is one of the most important problem in the large cities. The best way to reduce this problem is to use the underground tunnels. The excavation of tunnel and other underground structures lead to remove a part of insitu rock and soil masses and the considerable changes in stress conditions around them and surface settlement has been occurred, consequently. Therefore, estimation of surface settlement due to the tunnel excavation, especially in urban areas, is of great importance. The Niayesh subway tunnel was built in the northern part of Tehran and it includes north and south tunnels. From a geological point of view, the Niayesh highway tunnels are mostly placed in the Hezar Dareh Formation (A) and also some parts especially the eastern and middle parts of north tunnel are placed in Kahrizak Formation (Bn). The tunnels have been excavated by the New Austrian Tunnelling Method (NATM). In this method, primary shotcrete applied as a short-term support and the final lining is used to satisfy final support. In this paper, surface settlement has been studied by empirical methods, numerical analysis and real settlements. For the empirical and numerical methods, O’Reilly and New (1982) method and finite element method by PLAXIS2D software have been used, respectively. The five sections (CS-1 to CS-5) have been selected in order to study the surface settlement during Niayesh tunnel excavation. On the basis of the achieved results, the numerical method in all sections (except section 3) is in agreement with the real settlements. However, empirical methods have estimated the settlements more than real settlements in these sections. Also, the achieved results from real settlements, empirical methods and numerical analysis show that the maximum settlement due to tunnel excavation is more than allowable settlement and it places in the warning range.

The study area is located in the Trusted Zagros and is placed at the border area of Hamedan and Lorestan provinces. The main aim of this research is the assessment of karst development and its potential from geomorphology and hydrogeology point of view. Highly tectonization and distribution of dissolvable carbonaceous rocks is caused to develop karstification phenomenon in this area. Some of karstic geomorphologic features such as dolin, karren, cave and karst springs (for example Gamasiab spring) are formed. In order to evaluate the hydro chemical conditions of the area, the data from 26 springs were used. The results of data analysis show that the types of water in most of the springs are calcium and magnesium bicarbonate (Ca-Mg-Hco3) which is matched with the type of karstic aquifers. Assessment of the saturation indices of calcite and dolomite show that the most part of this area is under saturated by these two minerals. This means that the ground water doesnt travel in long distances. According to the results of dye tracing test, the mean velocity of groundwater is the same as velocity in karstic areas and shows the dominancy of conduit flow regime.