m. r. nikudel

Zanjan Angaran lead and zinc mine access tunnel with the length of 1133 meters has been excavated for underground extraction at a level of 2700 meters with an existing cross section of 7.5 square meters. The tunnel cross-section is to be increased to 20 square meters in order to access the trucks for cut and cover extraction. In this study, while studying tunneling and underground space stability methods, the stability conditions of Anguran mine access tunnel were investigated empirically, fuzzy hierarchical analysis. In the experimental method, while classifying rock masses by Q, RMR and GSI methods using Q classification results, two types of reinforcement were introduced, due to their greater conformity with the region, with 80% tunneling of type 2 with 2cm shotcrete and rockbolts with 2.5 meters length and 2.5 meters spacing. According to the same conditions in the empirical classification parameters using fuzzy hierarchical analysis, as a multilayer information analytical criterion based on the amount of overburden, RQD index of rock, spacing, rock and water strength in defined tunnel stability and weighting to layers and overlap In Arc GIS environment, a hazard zoning map is presented in the tunnel, which according to the map of the end of the tunnel has the highest risk of instability.

The purpose of physical modeling in structural geology is to reconstruct the formation, development and evolution of structures on a laboratory scale with materials similar to crustal rocks. The physical-mechanical properties of the materials used in these modeling are of particular importance; So that the characteristics of these materials should be similar to the physical and mechanical characteristics of crustal rocks, and there should be a proportionality between the model and nature in terms of rheology, viscosity, and frictional resistance. Sand, mud-clay, gypsum and silicon are among the materials used in physical modeling. Gypsum powder, plaster, or hemi-hydrate in dry and wet form (killed gypsum) has also been used in modeling. In this study, the effect of humidity on viscous behavior of wet plaster in physical modelling of strike- slip fault system has been investigated. In these modellings wet plaster with 320%, 285% and 175% of humidity as a viscous material has been used. In determination of physical and mechanical (Atterberg limits) properties of wet plaster, the liquid limit of 178% and plastic limit of 96% was obtained. This study also provides data on behavior of wet plaster with changes in its humidity.

Atterberg measurements were first used to measure the water content of wet (or dead) plaster. Based on this criterion, three limits are defined for the amount of wetness in the material, which includes the shrinkage limit, the plastic limit, and the liquid limit. In this study, due to the non-use of wet plaster in the humidity range of the shrinkage limit in physical modeling, the shrinkage limit test was not performed. In the plastic limit test, the minimum moisture required to turn the soil into mud is measured. In this regard, some balls of mud prepared from wet plaster are placed on a glass and by rotating the hand on the plaster, a rod with a diameter of 3mm is prepared. If cracks on the mud is developed, its humidity is at the level of mud. To determine the liquid limit of wet plaster, the penetrator cone device was used. Then the physical modeling of strike-slip faulting has been done using wet plaster with different wetness percentages. Three tests of physical modeling of strike-slip fault system in the basement and investigation of the effect of these movements on the sedimentary cover have been carried out using wet plaster with different humidity levels of 320%, 285% and 175%.

The results of Physical modelling on strike- slip fault system shows that by decrease in humidity of wet plaster from 320% to 175%, the Riedel shear fractures distance is increased from 0.3cm to 1.9 cm and their lengths have increased from 2.5cm to 4.5cm. These results obtained from the distribution and frequency of shear fractures in the form of a decrease in the number of fractures, an increase in the distance and length of fractures, and the uneven development of fractures qualitatively indicate a decrease in the elastic limit of wet plaster because of the decrease on its humidity. Reduction on the humidity of the wet plaster resulted in development fault related folding in the modeling. The variations on the numbers, distance, type and lengths of shear fractures in wet plaster with different percent of humidity demonstrates that wet plaster acts as viscous behavior when its humidity is between plastic limit (96%) and liquid limit (178%). These experiments also confirm the results of previous studies on the brittle behavior of plaster at lower wettnes levels.

The results obtained from this study in the investigation of Riddle shear fractures and folds related to the fault in the physical modeling of the strike-slip fault system showed that the water content in wet plaster to the extent of the plastic limit causes its plasticity behavior. The increase of water content more than this amount due to the relative decrease of adhesion and viscosity is associated with the decrease in the plasticity behavior of wet plaster. These changes are associated with the increase in the number of Riddle shear fractures and the decrease in the development of folds related to the thrust fault has been accompanied in the experiments. This conclusion is in agreement with the former studies that documented the brittle behavior of plaster with lower humidity than the humidity of the plastic limit.

Considering the diverse climatic conditions of Iran with a varying from hot and dry and also coastal areas it can be seen that salt weathering is one of the most important agents affecting on the durability of stones used as wall cladding of the building. As a result it is necessary that durability of stones be assessed and the most resistance and appropriate those be selected for use as wall cladding of the buildings. In this research, durability of six samples of travertines from Azarshahr and Mahallat areas against salt weathering were investigated. For this purpose, salt weathering test at sulfate sodium (Na2SO4) up to 60 cycles was carried out and, after every 5 cycles, changes in the samples appearance (color, efflorescence, chemical and physical decay), mechanical properties (point load strength, Brazilian tensile strength and P-wave velocity) and Dry Weight Loss of samples were monitoring and measured. The results indicated that changes in samples appearance including the color, efflorescence, chemical and physical decay due to criteria of measure those is qualitative, can not to be appropriate for assessment of samples durability against salt weathering. Moreover, results show in among parameters that criteria of measure those is quantitative, Brazilian tensile strength and P-wave velocity are more reliable in compare with point load strength and Dry Weight Loss for assessment of samples durability. Also, macroscopic monitoring of samples appearance against salt weathering show that petrological properties have major role in chemical and physical decay and therefore their durability.

From a strength point of view, lightweight concretes are categorized into three groups of structural, semistructural and non-structural concretes. The main purpose of this research is to determine the optimum mix design of a semi-structural lightweight concrete composed of pumice aggregates with the lowest unit weight and a reasonable compressive strength. For this purpose, the Taguchi method, with four eective factors and three levels, has been adopted. The method is a systematic design of experiments which can eciently reduce the time and cost of experiments. In this method, the most eective factors are selected and dierent levels are determined for each factor. Then, based on the number of factors and the assigned levels, a suitable orthogonal array is chosen using the Taguchi guideline. These arrays can provide a regular program for the experiments, including the number of tests and the combination of dierent levels in each test. At the end of each test, the corresponding quality criterion is obtained. Using the results of systematic tests via MINITAB software, the optimum combination is determined and, thus, the value of the quality criterion under optimum condition is predicted. In order to validate the accomplished study and evaluate the Taguchi method, a proof test, based on the optimum combination, is usually built, and its result is compared with the software prediction. In this research, due to the numerous factors aecting the compressive strength and unit weight of concrete, four governing factors are selected: pumice with sieve type 1, pumice with sieve type 2, sand and ller. In addition, pumice with sieve type 3 has been also selected as a complementary factor. The remaining materials, such as the ratio of water to cement, additives and cement weights, are considered as constant. In order to determine the optimum combination, the orthogonal array of L9 is utilized and after the analysis and determination of optimum levels, the results of laboratory proof tests and prediction of the Taguchi method were compared. The results demonstrate that the systematic Taguchi design method is very useful in reaching the optimum mix design of semi-structural lightweight concretes.

One of the most important issues in the design and implementation of engineering structures is to evaluate and investigate their durability against processes of consecutive wear، wet and dry. The durability of rock is resistance against chemical and physical weathering، the shape، size and status of the initial appearance in a long time and environmental conditions prevailing in the rock، hence it is important to evaluate the durability of rock. Since the device of standard durability (Franklin & Chandra، 1972) designed to evaluate and investigate durability of soft and argillites rocks. So، appears to be essential to design a durability device، which can evaluate hard rocks. For this purpose، Researchers of the Department of Geological Engineering، Tarbiat Modares University، durability device as «large-scale durability device» was designed and built which the length and diameter of the device، is 6 and 4. 3 times standard durability device، respectively، and needs 10 samples with weight of 400 to 600 g. In order to investigation the applicability of this device for hard rocks durability، we selected 17 building rocks samples of the igneous، sedimentary، metamorphic and pyroclastic rocks. Then their mineralogical، physical and mechanical properties were investigated. More، experiments of standard and large-scale durability up to 15 cycles were performed and data obtained were analyzed. The results show that، the large-scale durability device than standard durability، have more applicability for evaluating the durability of hard rocks.