Journal of Engineering Geology

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Considering the seepage and choosing an efficient sealing method is very important in dam projects. This issue has a close relationship with engineering geological properties of the dam site. Chapar-abad dam is an inhomogeneous earth-fill dam of 44.5 meters height, crest length about 427 meters and a reservoir capacity of 127 million cubic meters. The dam project is under construction and is located about 75 Km southeast of Uromieh city, in West Azerbaijan Province. The foundation materials include 60 meters of alluvium deposits overburden bedrock layers of carbonate units. The abutments consist of carbonate and schistose layers of Precambrian age. In order to control the seepage through the Alluvial foundation, several sealing methods were considered. The methods include grout curtain, cutoff-wall, impervious blanket, open compacted trenches, and the use of geosynthetics are evaluated. In this research using a finite element package named Plaxis was utilized. The results indicate that although the cutoff-wall is usually considered as the best method for this type of geological condition, but due to the instability of granular soils and the possibility of liquefaction capability, the grout curtain is proposed as to be an efficient method.

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Saymareh dam and hydro-power plant are under construction on Saymareh River in Ravandi anticline, Ilam province. During boring the power tunnel which crosses the anticline, a large volume of water was encountered. This volume of water was not observed in the past. Considering the water quality of springs, water level of dam site piezometers, geological and hydrogeological inspections, isotope analysis, tracing experiments and water balance, it was concluded that the main portion of water is not supplied by the Ravandi anticline. The neighboring Veizenhar, Gavar and Milleh anticlines contribute to providing the main body of water. The most probable paths of water are not cross the dam reservoir and a localized conduit flow is not established in this area. Therefore, water leakage from the reservoir is not expected.

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Groundwater is the sole source of accessible resource for agriculture in Zeviercherry- Kherran plains and water quality often falls in brackish group. In order to determine the source of salinity and hydrochemical processess affecting groundwater environment of the area, 61 groundwater samples were taken for hydrochemical analysis and composite diagrams (two variant diagrams of total concentration verses concentration of major ions and two variant diagrams of chloride verses concentration of bicarbonate, sulfate and sodium), Factor analysis and saturation index of calcite, dolomite and gypsum were applied. The data indicated that groundwater is supersaturated with respect to calcite and dolomite and with respect to gypsum saturated to under saturation. Regional dissolution of gypsum, anhydride and local dissolution of sodium chloride are important controlling factors of groundwater salinity of the area. 

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Results of velocity structure modeling in the Earth's crust using a comparison approach of receiver function analysis and joint inversion of receiver functions with surface wave dispersion data are presented in this paper. Seismograms of the teleseismic events that have been recorded on a broadband seismic station in the central Alborz were used for data processing. Velocity models that were computed by using both modeling methods show analogy the depth  discontinuities but differences in the absolute values of velocity. In addition, differences between computed models using different initial velocity models confirms that receiver function results are not a unique modeling method compared with the joint inversion results which show reasonable and stable values. Both methods show 56km depth for the Moho discontinuity.

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This paper describes the results of a study which was primarily directed to the determination of geotechnical properties of fine and coarse grain soils stabilized by lime obtained from Taleghan, northwest of Tehran to assess its suitability as construction material. Soils were treated with lime mixtures in various portions between 3 to 9 percents by weight. The samples were cured for different periods of time up to 90 days under 30°c and 60 percent relative humidity. The geotechnical properties were investigated by: (a) compaction characteristics, (b) compression tests and (c) direct shear tests. The results indicated soils maximum dry densities decreased while the optimum water contents increased. The compressive and shear strength of admixtures depicted an increasing trend. It was observed that addition of 6 percent of lime caused a significant increase in strength properties of CL and SC grain soils. However, the SC soil yielded the best results.

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It’s most crucial issues, evaluation of jointed rock masses strength for surface and underground structures behavior analysis. That’s not enough laboratory tests that was done on intact samples can’t preparing index of rock mass properties in the large scale. On the other hand, doing experience tests aren’t accepted for the assessment insitu rock mass strength, especially in the feasibility studies. While, it was happen slip surfaces in rock mass the best method to estimation of rock mass strength values is previous slides back analysis. Conventional method is used for this problem solving, Mohr-Coulomb and Hoek-Brown failure criteria. In this method essential rock mass parameters are determined with a lot method such as, engineering rock mass classification. According to the large changes of Sungun copper mine rock mass properties, for determination of mine slope material cohesion strength and internal friction angle uncertainties, effective parameters on rock mass properties are supposed as random variables statement finally for each run of drilling process rock mass classification was done. In this study, rock mass classification of Sungun copper mine slopes was done by using RMR and GSI methods. Confidence level of geotechnical parameters are determined 90% approximately. Then Monte-Carlo simulation method (MCSM) is used to produce the probability density function of mentioned random variables(C, ϕ). Result shows random variables of rock mass properties simulating were done with a suitable standard deviation and coefficient of variation.

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In recent years, availability of Satellite Data and power software packages for fast and cheap processing and analyzing of these data has been made that the big part of field geology operation was replaced by this technique. One of the most important problems of geological investigations is planning of geological map and discrimination of contacts of different rock units. Using satellite data of Irankoh region after processing and applying necessary corrections on them, as well as applying different classification algorithms in order to find The best geological map or optimal classification, best favorable algorithm for this way was obtained.

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Distribution of static active earth pressure on an inclined retaining wall, with frictional or cohesive-frictional backfill, has been studied in the present research. Based on the limit equilibrium concept, and by implementing the horizontal slices method (HSM), two formulations have been proposed for determination of critical failure wedge. Results obtained from these formulas and results of the suggested equations by other researchers have been compared. Findings of current study show that horizontal slices method is capable of predicting the stress distribution and angle of failure wedge for inclined walls with high degree of accuracy. In addition, this method is applicable for various conditions of soil and wall and is able to consider the slope of backfill, friction between soil and wall, cohesion of soil and the effect of surcharge, simultaneously. Application of achieved formulation from horizontal slices method reveals that active earth pressure on inclined walls is nonlinear for both frictional and cohesive-frictional soils and the center of mass point of the resultant force would be located in an elevation less than one third of the height of wall.

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One of the major problems in urban subway tunnels is tunnel stability analysis and determination of the safety factor, and the prediction of the settlement that caused to provide stability during the performance, and then at the time utilization structure. The objectives of this study is using different methods to predict and development of these methods by use of each other. In this  paper, analyze and evaluate the stability of Tabriz Metro tunnel- Line 1 has been carried out using numerical methods, artificial neural networks and empirical  equations. The two excavating methods used in Tabriz Metro tunnel- Line 1 (using machine TBM tunnel method and NATM). In the first part of this  research, the excavated zone of the tunnel with NATM method has been analyzed  using numerical method and surface settlement and amount of tunnel convergence in the tunnel walls have been predicted by this method. After that, surface settlement has been predicted using artificial neural networks and then it has  been compared with obtained value from numerical method analysis and empirical relations.  Then, based on these results, empirical relations of convergence - settlement have been modified for Tabriz Metro tunnel- Line 1. In the second part of the research, the TBM penetration rate was predicted by use of neural network which is an important parameter, when one faced with troublesome areas and is very useful to use appropriate pressure EPB for TBM.  

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Saline soils are of challengeable soils that may cause many problems in civil engineering projects. In this study, volume change behaviour of saline soils and also the effect of improvement and reinforcement on them have been investigated using laboratory tests as well as consolidation test, swelling pressure test and free swelling test. The case study is Amirkabir Highway which connects the cities Qom and Kashan.  Fifty four kilometer of this highway was deformed like waves due to existence of saline soils. The laboratory investigations showed that the studied soil has a considerable swelling potential which appears to be the main cause of damage to the highway pavement, therefore it is decided on improving the subsoil condition. The research program comprises of studying volume change behavior of saline soil, stabilized with lime and epoxy – resin polymer and reinforced with polypropylene fiber. Afterwards, results for two cases of stabilized and non-stabilized samples have been compared. According to the results, the main cause of swelling is soil disturbance and structure destruction of initial soil composition. Considering all of test conditions, it is appeared that, although lime is a traditional stabilization material but is economic for the most geotechnical projects and usage of polymer is suggested only in special applications due to its rapid setting

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The previous studies underteaken in the region indicate that the Ekhtiarabad and Chah-Darya sinkholes have occurred as a result of dissolution of underground gypsum rocks. Hence, they represent the likelyhood of hidden and threatening caves in the region. The presence of gypsiferous formations having surficial karstic features attest to this supposition. So, in order to determine the possible dissolving sites which may contain caves, the electrical conductivity and evaporite dissolution index maps of Kerman-Baghin aquifier were prepared and matched with groundwater recharge and mobility conditions. Accordingly, four suspected hidden- cave sites were recognized which include a large area around Ekhtiarabad village (as the most suspected site), one spot at the northwest of Baghin Plain and two other areas (south of Baghin and south and southwest or Kabutarkhan). Based on the utilized hydrogeochemical criteria, these last two areas may contain hidden caves, but, due to unsuitable hydrodynamic conditions, the possibility seems weak.

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A new approach is suggested to determine the permanent deformation of slope under seismic loading based on the horizontal slices method and limit equilibrium analysis. A comparison of the analytical results obtained from the proposed method for 3 sample slopes with those of previous research results is performed. The analytical method presented can be used to calculate yield acceleration, seismic coefficient of horizontal acceleration, permanent deformation and angle of failure wedge for slopes. Also, the stability analysis can be performed by proposed method. It was concluded that the horizontal slices method by analytical procedure proposed reliably calculates the permanent deformation of slopes.

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Today, one of the most problems, for the purpose of flood management is river flow prediction. Prevention of economic body suffering arise of flood is one of the most important achievements of correct flow prediction. Factors and divers parameters influence the discharge, make complex the analysis. Conception-physical model, regression models and time series are the most common- analytical approach of river flow. In this search by using of discharge data of Ghareh Ghanlo station in 13 years ago, the prediction of Sombar river discharge by Box-Jenkins was done. To do so, MINITAB software was used. Also for selecting of the best prediction model used of error evaluation factor and ARIMA (1,1,0) (2,1,1)12 was selected as the best prediction model and finally by use of these methods river discharge for 24 next month, was forecasted. 

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One of the main methods of determining dispersive potential of clay is chemical tests. These tests are found on the basis of sodium ion as a main chemical element in dispersive clay. The examinations show that there is no correlations between results of physical tests and chemical criterions. In present research after preparing the results of tests on 18 borrow pit sources of clay materials of earth dams, we investigate the Dr. Rahimi's criterion with results of Pinhole Test and then bases on pinhole test results, we suggested the modified criterion of Dr. Rahimi's proposed general criterion. The results of investigations on the range of laboratory data shows that the correlations of Dr. Rahimi's proposed criterion with pinhole test is 63%, while this rate is 74% for our suggested modified criterion. Also it should be considered that Dr. Rahimi's criterion compiled according the results of 24 laboratory samples while suggested criterion in present research compiled according the results of 234 laboratory samples.

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A regular set of large scale direct shear tests were performed to study gravel particle effects on shear strength characteristics of sands. The tests were conducted using direct shear apparatus with 300 mm × 300 × 170 mm shear box. Uniform, fine sand was used as the base material and mixed with 20, 40 and 60 percent of angular and rounded gravel grains with maximum size of 12.5 and 25.4 mm as oversized particles. All tests were performed on dry samples in drained condition. Samples were prepared in a relative density of 60 percent and tested using three surcharge pressures of 150, 300 and 450 kPa. According to the results, mixtures with angular and larger gravel grains show more shear strength and dilation compared to the mixtures contain rounded and smaller oversized particles. Enhancement of gravel content increases the effects of oversized particle on shear behavior of mixture. In this regard, some correlations for estimation of mixture's friction angle and shear strength were suggested based on gravel type and gravel content.

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The Alborz dam rock foundation is composed of marl and sandstone. With regard to the proposed plan for the grout curtain in marly rocks (relatively soft and plastic( which is significantly different from the hard and brittle rocks, the boreholes spacing (influence radius slurry), injection pressure (resistance rock), and even the composition and concentration of slurry are important. In the present paper, in order to evaluate the grout curtain of Alborz Dam, emphasis has been placed on two important parameters, namely, the coefficient of permeability and cement take. The results of cement take suggest that the distance between the primary boreholes is long and there is no proper connection between the primary and secondary boreholes. Moreover, grouting results of the fifth and sixth series of grout holes imply that the depth of some of the sixth series of grout holes has not been attained at the water tightening surface. A review of the rate of the cement take - time - pressure graphs and cement take - time graphs on the right abutment indicates that the injection pressure has not been applied in accordance to marly rocks leading to unfavorable phenomenon of opening and closing of joints (hydrojacking). Notably, the check holes results on the right abutment indicate that water tightening at this area has been provided a satisfactory and acceptable job.

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The main objective of this research is to provide information about the effects of mineralogical characteristics of aggregates on concrete properties. Crushed aggregates were selected with different petrographics from different resources. Aggregates such as, Marble, Dolomite, Tuff, Granite, Genasis, Basalt, Andesite, Lumashele, Sand Stone and Diorite which have different chemical, physical and mechanical properties were used in this study. The results of the study showed that physical and mechanical properties of minerals control properties of concrete and undesirable properties of concrete influenced with which of mineral. Also, the results indicated that aggregates with flaky and elongated minerals subjected to weathering have a great effect on undesirable properties of concretes. The highest uniaxial compressive strength (33 MPa) at 28 curing days was measured in the specimens prepared with dolomite aggregates while the lowest strength (13 MPa) was measured in the specimen prepared with lumashele aggregates at the same age.

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One of the most important issues in the Reverse Analysis is analyzing the density resulting from the compaction of in fine soils. The conventional methods in d etermination of soil density are: sand cone, rubber balloon and nuclear density gauge. Trained neural network, as a suitable alternative for conventional methods based on models analyzed by those methods, is not only as accurate but it is also easier to calculate and implement. In the present article, a model based on multilayer perceptron of neural network is presented for prediction of the behavior of fine soils density in Sarabi Dam. The paper presents the implementation process and density of the soil layers. The input variables include 4 geotechnics and 4 implementation parameters. The geotechnic parameters consist of: optimum moisture content, maximum specific gravity, liquid and plasticity limit implementation parameters consist of: the number of cross rollers, thickness of the layers and density and moisture of the soil obtained from the site. The model is based on multilayer neural network, using the error back propagation approach and it is capable of calculating the density. As a result, the maximum specific gravity laboratory, using the aforementioned geotechnic and implementa-tion parameters, is presented. The method compates the maximum specific gravity laboratory accurately at almost 100 percent.

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Huge amount of scarp tires have made a big environmental problem that its reduction assessment is an important aim for researchers. Reusing of these materials in different branch of industrial is concentrated. Because of elastic behavior and absorbing the energy, waste tires are concerned as a famous damper. As a more effective manner to check the seismic forces is reducing the entered movements to the structure, it seems that using soil-scrap tire mixtures acts as seismic damper and these mixtures can reduce the earthquake forces acting to the structure. In this research this mixture is modeled as a damper under the foundation and the bed rock depth is analyzed in both time and frequency domains. Obtained results show that using soil-tire mixture reduces the resonance amplitude, energy and the acceleration reached to the ground surface. It should be mentioned that increasing the depth of the bed rock, the act of the mixture as a damper reduces. The results show that this mixture has a better operation in strong ground motions. Using these materials is cheaper compared with other base isolation systems, more available, not requiring high technology and also it reduces both earthquake forces and environmental problems.

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In this research, it is attempted to develop a new classification system for evaluating the rock sawability with respect to affective and major parameters. In this new classification system, four major characteristics of rock are selected for evaluating the rock sawability. In total, each rock takes a new score from 10 to 100 and classified into five classes: very poor, poor, fair, good and very good by new classification system. The new calculated rock sawability index (RSi) can be use as a useful index for evaluating the rock sawability. In the present paper, the relationship between ampere consumption, RSi and machine parameters are investigated by multiple regression. For this propose, 12 stones are tested by new sawing machine under different machining conditions (different depth of cut and feed rate). The results of this step are used as input data in SPSS software. Finally, two predicted models are presented with respect to machining parameters and RSi. These new models in stone factories can give a good viewpoint of energy consumption