مجله زمین شناسی مهندسی
سال نهم شماره 3 (پاییز 1394)

Measuring of uniaxial compressive strength (UCS) of intact rocks is necessary in many engineering projects. In deep well drilling for petroleum production or exploration drilling in deep tunnels، because depth wells، obtain suitable core samples for UCS test is too extensive and sometimes impossible. Therefore indirect method for UCS determine (for example using rock particles) is common. One of these methods is known as indentation test. In this test an indenter that is hard penetrate in to rock particle which surrounded by resin is used. In this paper، 11 microcrystalline limestone block samples from carbonate Zagros formation outcrops is prepared and UCS test in laboratory is performed. Then cores are crushed and 720 rock particle samples with 2، 3 and 4 millimeters size is prepared. Indentation test with indenter 0. 6، 0. 8 and 1 millimeters diameter is done and critical transitional force (CTF) for each particles is determined. Empirical equation between UCS and CFT for different samples and indenter with R2≥0. 78 is suggested. Using multiple regression general equation between UCS، CFT، particle size (D) indenter diameter (I) with R2=0. 85 is proposed. Verification of the proposed equations with 135 indentation tests on 3 microcrystalline limestone samples and comparing measuring UCS in laboratory with estimate UCS are evaluated. This comparison showed that 88% they are similar.

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 pseudo-static analysis is one of the conventional methods in embankment dams design and International Commission on Large Dams (ICOLD) suggests using this method before ultimate dynamic analyses. In this research, the static, pseudo-static and dynamic analysis of Masjed Soleyman embankment dam have been performed. Using dynamic and pseudo-static analyses results, the safety factor of critical sliding surface were calculated. Permanent displacements of critical sliding surface were evaluated by Newmark method and the calculated safety factor was compared. Based on the comparison results in different water levels of the reservoir and by introducing a new equation, the variable horizontal acceleration coefficients in height of the dam body were calculated. Finally, obtained horizontal acceleration coefficients were compared with other criteria introduced in different embankment dam's design codes. Totally, the results indicate that the proposed method leads to a larger horizontal acceleration coefficient in higher parts of the dam body.

Studies show that earthquake causes chemical and physical changes in ground water. These changes can be recorded and used as geohydrologic precursors. Also according to recent research while earthquake and before, the waves of electromagnetic field of the earth vibrate, these vibrations are called magnetic anomalous. In earthquake knowledge, this type of anomalous is known as geohydrologic precursors. So the purpose of this research is to study the feasibility of the correlation between two precursors (geohydrologic and geomagnetic). In this study, to consider the effects of magnetic field on physical and chemical characteristics of water (i.e., electrical conductivity, total dissolved solids, and water level), a number of experiences have been done that can be used in short term and long term earthquake prediction. According to the results of statistical analysis, there is a meaningful partial correlation (confidence coefficient=95%) between magnetic field (geomagnetic precursors) and physical and chemical characteristics of water (geohydrologic precursors).

In this research, predictions Strength of Concrete containing different aggregate using Non-destructive (Ultrasonic) testing through Artificial Neural Networks were carrying out. For this purpose, aggregate materials gathered with the different properties from the quarries and then their destructive and nondestructive properties obtained in laboratory.The important point of this research, using different aggregate with physical, mechanical and chemical properties, and using two different methods, such as Non-destructive static and dynamic testing, Uniaxial Compressive Strength and Compressive wave velocity, respectively. Thus, model includes various types of samples, also estimate and predict model includes static and dynamic tests. The results showed that the use of artificial neural networks will not only increase the accuracy, but also reduces costs and time. In this research, predictions Strength of Concrete containing different aggregate using Non-destructive (Ultrasonic) testing through Artificial Neural Networks were carrying out. For this purpose, aggregate materials gathered with the different properties from the quarries and then their destructive and nondestructive properties obtained in laboratory.The important point of this research, using different aggregate with physical, mechanical and chemical properties, and using two different methods, such as Non-destructive static and dynamic testing, Uniaxial Compressive Strength and Compressive wave velocity, respectively. Thus, model includes various types of samples, also estimate and predict model includes static and dynamic tests.

In present research, landslide hazard zonation of Latian dam watershed area has been carried out using Analytic Hierarchy Process (AHP), Valuing area accumulation, Factor overlay and Information value methods. In order to determine the most important factors affecting landsliding, different maps comprising slope, aspect, altitude, faults, drainage network, access roads, lithology, land use and friction angle maps were prepared digitally using aerial photos, maps, data and field investigation. Afterward affecting factors were evaluated using encountered old landslides. The results of evaluation show that lithology, the distance from fault, slope, dip direction, land use, the distance from road and stream are important effective factors on sliding in this area. These parameters were leaded to landslide zonation maps. These maps show that potentially high risk zones point of view landslides are located near the central and western boundaries of the reservoir which are needed special attention.Performance of four used classification methods were evaluated and compared by Indexes of Quality Sum (QS), Density Ratio (DR) and Precision of the Predicted (P). The evaluation results show that Valuing area accumulation and Factor overlay are precise methods for evaluating landslide potential in the study area respectively.

Excessive and unpredicted tool wear is one of the major challenges in mechanized excavation in tunnel projects.This problem, due to more demand for maintenance, increases excavation time in addition to cost overruns. For obtaining of a proper view about relation between performance parameters of the TBM and abrasivity, a new laboratory test machine is built in Engineering Geological Laboratory in Ferdowsi University of Mashhad, Iran. In this paper the results that achieved from performing tests on silica samples by the laboratory machine is presented. For this purpose 36 tests with various amount of surcharge and rotation speed at different times on coarse silica sand carried out. The obtained results have shown direct relation between test duration, surcharge and rotation speed versus weight loss. For example a direct linear relation between the tools wear and surcharge and/or rotation speed was observed. Indeed a logarithmic relation was gained for the time effect.

Buried pipeline system form a key part of global lifeline infrastructure and any significant disruption to the performance of these systems often lead to undesirable impact on regional business، economies or the living condition of citizens. In this paper the response of buried pipelines at fault crossings are studied. A fault movement can be resolved into an axial component، a lateral component in the horizontal plane، and a vertical component. Applying finite element method، the effect of various parameters such as anchored length، internal friction angle of surrounding soil، fault movement and fault crossing angle on the behavior of buried pipeline were studied. Nonlinear behavior for pipe and surrounding soil are assumed using beam-spring model. Results showed an increase in internal friction angle of surrounding soil increases strain and also normalized bending moment and axial force. Comparing bending moment at friction angle of 20° and 40° shows about 30% differences with certain crossing angle we can prevent producing large strain and bending moment on pipeline.