Journal of Engineering Geology

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The ever increasing growth and development of the metropolitan city of Karaj in recent years has placed implementation of basic studies on Alluvium of Karaj Plain on the top of significant priorities of the region’s development projects. Therefore, in the present paper, the alluvium of South Karaj was studied based on relevant numerous geotechnical laboratory and field tests. In this regard, an area from Pol-e Fardis to Serāh-e Andishe with a length of 10 km is selected and the geotechnical engineering features of this area were taken into careful consideration and study. The carried out studies divide South Karaj Alluvium into five independent parts whose engineering description are presented. On the other hand, since the results of most of relevant laboratory and field tests have been collected, some relations for calculating Elasticity Modulus, Soil Inner Friction Angle as well as other geotechnical parameters in South Karaj Alluvium are introduced. Finally, the process of soil classification in South Karaj Alluvium is compared with the same process in other regions of Karaj, and, given the soil engineering features of Southern part of South Karaj Alluvium, some suggestions are presented for optimization and facilitation of future development projects in south Karaj Alluvium. Geotechnical studies.

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Rock fall hazard assessment is a fundamental land-use planning tool in high mountain area, where human settlements progressively develop across side valley areas, using the worth of potential losses and the restoration costs. The aim of this paper is to evaluate the potential of rock falls along the north east of the Yadak village. This village is located in the Khorasan-Razavi province near the Ghochan city in the northeast of Iran. The existence of the Tirgan limestones with abundant joints and fractures in the north part of the Yadak village causes instability such as rock falls that provide many problems for the residents. Many factors such as rock type, slope morphology, drainage pattern and the seismic activity are considered in this research as affecting factors. For joints investigation in the study area, the dip and dip direction of more than 180 discontinuities measured and analyzed using dips. Since most of the slope instability along the north part of the Yadak village are the rock falls type. Rocfall software was used to investigate the rock fall mechanism. Finally, the rock fall hazard zonation map is prepared using GIS program.

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Abstract
(Paper pages 1159-1178)
Young’s modulus measured as the slope of the stress-strain curve under static loading conditions (Es) in the lab is one of the most essential parameters for reservoir geomechanical modeling. However, information on the value of Es along the well length is often discontinuous and limited to cross well with the core. On the other hand, well log data for wave velocities Vp and Vs are often available for most hydrocarbon reservoirs. Hence, well-known equations are needed to calculate static Young’s modulus based on the compressional and shear wave velocities (Vp and Vs) that is dynamic Young’s modulus (Ed). Unfortunately, because of porosity and micro cracks in rock texture, Es and Ed are not equal. Therefore, correlation between static and dynamic parameters could result in a continuous and more reliable knowledge on the elastic parameters along the well length. In this research, laboratory experiments were carried out on limestone rock core specimens of Sarvak formation obtained from an oil well in the South West of Iran. Empirical relations were suggested to estimate UCS and static Young’s modulus from compressional wave velocity (Vp) and dynamic Young’s modulus. These empirical relations are prerequisite for continuous wellbore stability analysis in oil and gas well drilling

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Schmidt hammer is used for calculation of joint compressive strength and elasticity modulus of rocks. Today, application of Schmidt hammer is a common method in evaluation of properties of rocks. This method is quick, inexpensive and non-destructive which are benefits of this method. In this regard, different experimental equations proposed by Barton & Choubey (1977), Deere (1960), Keadbinski (1980), Aufmuth (1973) and ISRM (1981) can be employed in order to calculate the Joint Compressive Strength (JCS) of rocks. Due to the importance of this research, new experimental equations are introduced. Using this equations show a very good results in comparison with the results of other researchers. It should be noted that this equations are achieved from 827 records of Schmidt Hammer results from different types of hard rocks such as granite, diorite and hornfels from the Ganjnameh-Shahrestaneh road in Hamedan province, west of Iran.

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Abstract (Paper pages 1179-1194) The site under study is located in the south of municipality-13, east of Tehran. Numerous building construction activities and large investment have been done in this area. Hence, it is important to have a good knowledge of the site characteristics. Soil classification is a very effective tool for optimum engineering construction which may reduce the future earthquake hazards. Building codes such as standard No. 2800, UBC, IBC and Eurocode 8 were used for soil classification. Seismic and geotechnical data were collected. Based on the considered Building codes the average seismic velocity and SPT values were estimated. It was concluded that Piroozi Street can be grouped into II, SC, C and B classes.

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Abstract
(Paper pages 1059-1076)
Physical and mechanical properties of intact rocks are very important in civil engineering works that interact with rock such as underground structures, dams,foundations on rock, and rock slopes. Therefore geomechanical parameters such as compression strength and deformation modulus of rock can have fundamental importance in the different stages of design. Determination of these parameters is time consuming and costly. Since Asmary formation has broad outcrop in the west and southwest of Iran and many large projects are located in this formation, therefore it is a requirement to accomplish the present research. This paper is dealing to analyzing data from laboratory of two major projects of the Khersan 1 and 2 dam sites. In this regard, the physical, mechanical, dynamic and durability properties of intact rock and geology controlling agents of these changes has been evaluated and analyzed. Finally, new experimental relations between different parameters have been presented.

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All rockfill materials subjected to stresses above the normal geotechnical ranges exhibit considerable particle breakage. Particle breakage and crushing of the large particles to smaller ones result in a lower strength and higher deformability. The breakage of particle that is observed in the large scale triaxial tests, is usually expressed quantitatively by the Marsal breakage index, . This paper presents a method for calculating at any axial strain level in the large triaxial tests. The model used Rowe’s minimum energy principle ratio. The key parameter in modeling , is the friction angle which excludes dilation and breakage effects, . The results indicate that the internal friction angles at confining pressure equal and less than 200 kPa at the constant volume state is a unique value. Moreover, there is a linear relationship between the variation of energy spent on particle breakage to Marsal Breakage index with confining pressure, at failure axial strain.

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Tunnel boring machines (TBM) are widely used in excavating urban tunnels. These kinds of machines have different types based on supporting faces and tunnel walls. One type of these machines, is the Earth Pressure Balance (EPB) type that was used in excavating the Line 1 Tunnel of Tabriz Metro. Different parameters such as geological conditions, rock mass properties, dip and machine specifications affect the efficiency of the machine. One method of predicting the efficiency of these machines is to estimate their penetration rates. In this study the value of TBM penetration rates are predicted by an artificial neural network. Predicting of this parameter is so effective for conducting in high risk regions by understanding the time of facing to these regions. The main result of this study is to forecast the penetration rate with an acceptable accuracy and to determine the effective parameters through sensitivity analysis measured by an artificial neural network.

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The development of large cities requires the use the underground networks for the construction of transportation infrastructures and facilities. Construction of tunnels in soft grounds induces generally soil movement, which could seriously affect the stability and integrity of existing structures. In order to reduce such movements, in particular in urban areas, contractors use more and more the tunnel boring machines (TBM) for the construction of tunnels. Hence in urban environment, Prediction of the ground movements caused by the tunnel excavation is a major engineering challenge. In this paper is used a three-dimensional numerical model and ABAQUS cod for the prediction of soil movements induced during tunnel construction in part of the line 3 of Tehran subway using EPB excavation machine. This investigation include most shield tunneling components such as face pressure, the grouting pressure, excavation machine and frictional contact with soil and shield. Observations of the results demonstrate that the maximum surface settlement in this section is 2.5 cm that is 0.5 cm more than the its allowable value. Simultaneously with surface settlements occur horizontal movements within soil mass, which have different forms in two horizontal directions, and with the expansion of depth they increasing.

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In the karstic areas, detailed studies of phenomena such as seepage of water from hydraulic structures and land subsidence in the residential and quarry areas  is of  higher importance. In this study, the dissolution rate constant of gypsite samples of Gachsaran Formation, obtained from the Chamshir dam reservoir, were measured equal to 0.24×10^-3 cm/sec. Then, the changes of amounts of joint apertures using theoretical and experimental (by changes of joint water flowing and direct measurement) methods were calculated. The results showed that the predicted aperture for joints calculated through theoretical method is less consistent with the measured value of the changes of joint water flowing while the value measured by direct method (measured using a caliper) compliance is higher. Also based on research findings, if gypsites of the dam reservoir are exposed to the water flow, the amount of aperture of a joint with 0.5 cm initial opening will increase to 10 cm after about 278 days. This increase in joint aperture compared with the useful life of the dam draws for special attention to water tightening of dam reservoir.

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In this paper, using Mononobe & Okabe method, seismic force and its effects on thin masonry retaining wall inside structural frame (Masonry retaining infill) are presented. In this method, retaining wall has been assumed to be rigid and the prevailing failure mode is sliding of wall bed joint or wall rotation around its toe, whereas the prevailing failure mode of masonry retaining infill is usually flexural cracking in middle zone of wall under out of plane seismic force. In this case, the seismic force distribution is important. Accordingly in this paper, a distribution for seismic forces on masonry retaining infill has been proposed. Also with regard to out of plane behavior of masonry retaining infill in terms of strength and acceptance criteria aspect, failure in body of wall due to out of plane loads has been analyzed. Then, the desired seismic rehabilitation method in case of vulnerable masonry retaining infills has been presented and as a practical example, results of the proposed method with the results of numerical software have been controlled. Finally, according to various conditions predicted for masonry retaining infills, Seismic Retrofit solutions are presented for practical applications.

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Discontinuities have properties such as orientation, number of set and frequency that can affect the rock strength. Rock specimens having one, two and three cross- sets of discontinuities, various frequencies and orientations of 0, 30, 45, 60 and 90 degrees were prepared. The numbers of rock pieces increased progressively with an increase of frequency and set of discontinuities. As specimens having three sets of discontinuities that one of their sets had four number of parallel discontinuities were consisted 20 rock pieces and they represented jointed rock mass. Joint factor, uniaxial compressive strength and friction angle along the discontinuity surface in direct shear were determined. The uniaxial compressive strength of specimens having one, two and three sets of discontinuities in horizontal and vertical direction was less than the uniaxial compressive strength of intact rock. The uniaxial compressive strength of specimens approached approximately to zero value particularly when the orientation of discontinuities was 60 degrees. This considerable decrease of strength was occurred also for specimens having two and three sets of discontinuities at orientation of 30 degrees. The analysis of results showed that the relationship between ratio of uniaxial compressive strength of jointed specimens to the uniaxial compressive strength of intact rock specimens (anisotropy factor) and joint factor of this research is considerably different with the suggested relationship by Ramamurthy. Properties of discontinuities have altogether essential role on the strength of rock mass.

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Slake durability of rocks is an important engineering parameter for evaluating deterioration of rocks in chemical and physical agents that are related to mechanical properties of rock. The main purpose of this study is to assess the influence of the number of drying and wetting cycles under variable pH conditions and controls of mineralogical composition on durability. For this purpose, five different types of tuff were selected from different parts in north Qazvin city. The samples were subjected to multiple-cycle slake durability testing with different pH values solution. Also the slake durability tests in saturated condition on samples, petrographical analyses and basic physical - mechanical test were performed. In addition, to assess the influence of mineralogical composition on durability, the mineral contents of the original material and the material passing from the drum of the slake durability apparatus after fifteen cycles were also determined by XRD analyses. It was concluded that the slake durability of tuff is independent of the pH in acidic solution circumstances. Mineralogical composition, fabric and weathering rate are considered to have a greater influence on the slake durability of tuff. A strong relationship between the point load strength and the fifteenth-cycle slake durability index is found in the rock types studied.

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Prediction of location of future earthquakes with event probability is useful in reduction of earthquake hazard. Determination of predicted locations has attracted more attention to design, seismic rehabilitation and reliability of structures in these sites. Many theories were proposed in the prediction of time of occurrence of earthquake. There is not a method for prediction time of future earthquakes. Many studies have been done in the prediction of magnitude of earthquakes, but there are not any investigations on prediction of earthquake hazard zonation. In this study, the locations that have probability of the event of future earthquake have been predicted by artificial neural networks in Qum and Semnan. Neural networks used in this study can extract to complicate properties of patterns by receipting the interval patterns. Furthermore, the map of earthquake hazard zonation has been drawn. Properties of occurred earthquake were collected since 1903. The most probable event of earthquake in Qum has been predicted 31.6% in center, and 28.9% in north of Semnan

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The Water infiltration rate of a catchment area depends on a number of parameters. Each catchment area has its own peculiar infiltration features, depending on its climate and soil structure This research is a study and comparison of the banks of two permanent rivers of Bushehr Province (Iran), namely, the Mond and the Bahoosh, in the County of Tangestan. In order to determine and check the best penetration model and to calculate the infiltration coefficients of the Kostyakov-Lowese, SCS, and Philip models, the vertical water penetration rate of the soil was measured using field Double Ring tests (repeated for three times) in 60 test pits. Using computing software, the infiltration and aggregate infiltration rates’ curves were drawn and a Visual Basic software program was used for each model to specify the best coefficients, that is, those with the highest correlation with the curves. Results show that, for the Bahoosh riversides, the American SCS infiltration model has less errors than the Philip and Kostyakov-Lowese models, and for the Mond riversides, the Philip model is better than the Kostyakov-Lowese and American SCS models.

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The shape of slip surface of the wedge creating lateral thrust on rigid retaining walls plays an important role in the magnitude, distribution, and height of point of application of lateral thrust.  Considering the shape of slip surface as linear, circular, logarithmic spiral, or a combination of them has been used in the literature. In the Coulomb lateral earth pressure method, a linear distribution of soil pressure on retaining walls is tentatively assumed and thus the point of application of total thrust is placed at one third of the wall height from the wall bottom. However, some experimental studies have revealed non-linear distribution of lateral earth pressures and that the point of application of resultant thrust is placed upper than one third of the wall height. In the present study, a plasticity equation is used to determine the reaction of the stable soil on cohesionless backfill supported by a retaining wall using an empirical equation derived from experiments performed in the field by others. A new analytical solution for determining the total resultant thrust on the wall is introduced and the distribution of pressures and the point of application of total thrust are computed. The results have been compared with some analytical methods, experimental data, and also with available data reported from field, demonstrating the accuracy and capability of the developed method. The results show that the distribution of the active lateral earth pressure is nonlinear and the point of application of total thrust is located about 0.42H from the wall bottom (H=wall height). In addition, the application point of total thrust is nonlinear function of soil-soil, wall-backfill soil friction angels and the height of the wall

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Construction of asphaltic core dams is a relatively novel method especially in Iran. Iran is located in a region with high seismicity risk. Therefore, many researchers have focused on the behavior of such types of dams under earthquake loading. In this research, the behavior of asphaltic core rockfill dams (ACRD) has been studied under earthquake loading using nonlinear dynamic analysis method and a new method is presented to assess seismic stability of these types of dams in earthquake conditions. Based on nonlinear dynamic analysis, the current study attempts to provide an appropriate criterion for predicting the behavior of earth and rockfill dams considering real behavior of materials together with actual records of earthquake loading. In this method, the maximum acceleration of the earthquake record (PGA) increases until instability conditions. Finally, a new criterion is presented for evaluating seismic safety of ACRDs via demonstrating curves of the crest's permanent settlement and maximum shear strain against maximum earthquake acceleration. Results of the proposed criteria can assist designers of asphaltic core dams to predict dam stability during earthquake event

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In this paper, a constitutive model is proposed for prediction of the shear behavior of a gravely sand cemented with different cement types. The model is based on combining stress-strain behavior of uncemented soil and cemented bonds using deformation consistency and energy equilibrium equations. Cement content and cement type are considered in a model as two main parameters. Based on the proposed method, the behavior of cemented soil with different cement types is predicted for conventional triaxial test condition. Porepressure developed during undrained loading besides volumetric strains in drained condition are also modeled according to this framework. Comparison of model results with experimental data indicates its reasonable accuracy.

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Shear wave velocity (Vs) is a basic engineering soil property implemented in evaluating the soil shear modulus. Due to a few limitations, sometimes it is preferable to determine Vs indirectly by in situ tests, such as standard penetration test (SPT). However, inaccuracies in measurement or estimation of the influencing parameters have always been a major concern, and thus various statistical approaches have been proposed to subdue the effect of such inaccuracies in predictions of future events. In this article, an innovative approach based on robust optimization has been utilized to enumerate the effect of such uncertainties. In order to assess the merits of the proposed approach a database containing 326 data points of case histories from Adapazari, Turkey were gathered from renowned references. The identification technique used in this article is based on the robust counterpart of the least square problem which is a second order cone problem and is efficiently solved by interior point method. A definition of uncertainty based on frobenius norm of the data is introduced and examined against correlation coefficient of various correlation parameters and optimum values are determined. Finally the results of new correlation are compared with those utilizing a commonly used statistical method and the advantages and possibilities of the proposed correlation over the conventional method are highlighted

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Time history analyses as crucial means in many earthquake engineering applications are highly dependent to characteristics of the seismic excitation record so that the resulting responses may vary from case to case. Strong ground motion scaling is a known codified solution to reduce such a dependency and increase reliability of time history analyses. The well-known code practice may result in highly non-economic designs due to considerable error in the spectra scaled to match the target code spectrum. This problem is formulated here in an optimization framework with the scaling coefficients as the design variables. Harmony search as a recent meta-heuristic algorithm is utilized to solve the problem and is applied to the treated examples. Using a variety of target period ranges the scaling error is evaluated and studied after more unified via optimization. The effect of base structural period and interval variation on the scaling error is then studied in addition to considerable error decrease with respect to traditional code-based procedure. The results also show dependency of spectral matching error to the period-interval elongation/variation, the base-structural period and more error sensitivity for narrow-band resonance with the filtered records on softer soil types