ENGINEERING GEOLOGY
Year:2019 | Volume:11 | Issue:4|Papers Count:7

In the academic and industrial environments of Iran، there is little understanding of the relationship between geological science and technical branches of mechanics and electronics. Such concepts are not explained in Iran's higher education curriculum، and almost no source of research has been published in Persian. The history of collaborative studies between mechanical engineers and geoscientists can be considered at the onset of the topics of the Terramechanics. In this research، by studying the excavation conditions in Bazideraz tunnel، the necessity of initiation of interdisciplinary studies of geology graduates with the mechanical engineers in higher education and industries of the country is discussed. In this paper، with the analysis of the operational parameters of the TBM and the study of geological conditions، discusses how to change the structure of the TBM. The results show that in this project، in order to adapt the structure of the machine to the geological conditions of the route، a series of structural reforms including the removal of 26 thrust jacks، the installation of 9 probe drilling holes in the shield، the removal of all passive articulation cylinders (16 jacks)، a change in the arrangement of the disc cutters، and the construction of 7 gearbox converters to increase the rotary speed of the cutterhead، inevitable.

Freeze-thaw process is one of these factors which extensively affects rocks and concrete properties. Thus، taking its impact on physical and mechanical properties of materials into account is required in the regions susceptible to the process. In most of the previous studies، the freezing and thawing periods' temperatures and their duration were chosen regardless of the weather conditions of the regions susceptible to the freeze-thaw process and regarding cement-based materials، the investigations were focused on concrete and there are a few studies on freeze-thaw effect on cement mortar. This study addressed the effect of number of freeze-thaw cycles on porosity، uniaxial compressive strength and Brazilian tensile strength of sandstone and cement mortar specimens considering the climatic data of western and northwestern regions of Iran in which the occurrence of freeze-thaw process is possible. Furthermore، the computerized scan (CT) was carried out on the sandstone specimen to examine the damage resulting from freeze-thaw. The results indicated that the increase in the number of freeze-thaw cycles caused in linear increase in the porosity of the specimens، while reducing their uniaxial and tensile strength. The study of the CT images also showed that the damage factor was increased by increasing the number of cycles.

In most surface mines، the convention empirical methods are used to design the blasting pattern that leads to the undesirable results and increasing the production costs. In this research، the Delpat software package was utilized to simulate and optimize the blasting pattern of Boghde-Kandi quarry rubble mine. For this purpose، mine information was firstly collected and essential rock geomechanical parameters were measured. Then using the above-mentioned software، simulation of blasting pattern was conducted for hole diameters i. e.، 76، 89، 102 and 115 mm. Comparison of the costs related to selection of each of the above hole diameters showed that overall costs were decreased by increasing in hole diameter. However، higher hole diameter required the greater volume of explosives which causes further ground vibration and flyrock. By utilizing the greater hole diameters، official buildings and; crushing and grading equipment sites will be located in the flyrock and ground vibration area and may be damaged. On the other hand، applying the hole diameter of 102 mm leads to the considerable cost decreasing (0. 08 $/m3) compared to the 76 mm hole diameter that currently is used in mine. Therefore، hole diameter of 102 mm was proposed as an optimum one. According to this hole diameter، other parameters related to drilling and blasting pattern were calculated and proposed to perform in practice. Practical implementation of the blasting operation based on the suggested pattern leads to improve fragmentation and minimizing costs and side effects compared to the previous pattern.

Brittleness is one of the most important mechanical properties of rock that is widely used in geotechnical designs such as drilling operations and underground structures. So far، standard method for estimating the brittleness of rocks have not been introduced and therefore، indirect methods are used to estimate them. In this research، brittleness of granitic rocks are estimated from Schmidt hardness and petrographic characteristics (minerals mean size and mineralogical composition) using simple and multivariate statistical relationships. To achieve these goals، 10 different granite rocks were collected from quarries Tavandasht and Gosheh around Borujerd (Lorestan province). Based on laboratory tests، brittleness index، Schmidt hammer hardness، minerals mean size and quartz to feldspar ratio were determined. Then، different models were fitted to the data for estimating the brittleness. The results of simple statistical relationships indicate that there are moderate correlations (determination coefficients ranging from 0. 70 to 0. 87) between the brittleness index with Schmidt hammer hardness، minerals mean size and quartz to feldspar ratio. While the multivariate statistical relationships indicate a significant effect of the minerals mean size and quartz to feldspar ratio on the accuracy of correlation between the brittleness index with Schmidt hammer hardness s (with determination coefficients of 0. 91 and 0. 93، respectively).

The aim of this paper is to study the effect of spacing of the joint from ‘ u’ shape cutter on the fracture mechanism and to investigate the effect of joint angularity under ‘ u’ shape cutter loading on the shear failure mechanism. For this purpose nine sample with dimension of 5 cm *10 cm*10cm consisting non-persistent joints were prepared. The first sets of three specimens have one non-persistent joint with length of 2cm and angularity of 0، 45 and 90. The spacing between joint and top of the sample was 2cm. The second sets of three specimens have one non-persistent joint with length of 2cm and angularity of 0، 45 and 90. The spacing between joint and top of the sample was 4cm. The third sets of three specimens have two non-persistent joint with length of 2cm and angularity of 0، 45 and 90. The spacing between upper joint and top of the sample was 2cm and the spacing between lower joint and upper joint was 2cm. the samples were tested under loading rate of 0. 01 mm/s. concurrent with experimental investigation، numerical simulation were performed on the non-persistent joint using FRANC2D. the results shows that the spacing between joint and specimen edge and joint angularity have important effect on the crack growth mechanism. Also، failure mode and failure pattern in experimental test and numerical simulation are similar.

Landslide-dammed lakes are a geological phenomenon that، despite of its beauty can be studied as a geologic hazard. Seymareh rock avalanche has created at least three dams and lake landslides in southwest Iran. Jaydar dam is a horseshoe-shaped landslide dam is composed from large rocky blocks. The length of the dam is more than 11، 000 m and average height is 140 m from its bedrock. This dam is formed on the permanent Kashkan River in south ofPoldokhtar city and between the Sarab Jahangir and Baghe Jaydar villages. Due to the geometry dimensions and stability of the dam until now، it could be the oldest and largest rocky landslide dam in Iran. Jaydar Lake is the 2nd landslide lake in region، has a length of 36، 000 m and an area of 65 Km2. The Jaydar Lake has expanded from the south of Poldokhtar city to Jolgeh Khalaj village on the Poldokhtar-Khorramabad road. The Present Research shows، that the formation and death of Jaydar Lake are in 4 stages. 1. Seymareh rock avalanche and formation the Jaydar landslide dam. 2. The closure of Kashkan River route 3. Formation of the landslide lake behind of dam and filling up to 740 meters above sea level (m. a. s. l). 4. Lake drainage through a valley (spillway) on bedrock in the northwest of the lake. 4. Discharge of lake water by a solution channel (spillway) in the Gachsaran Formation (bedrock of The Jaydar Lake).

In recent years، along with the drying of Urmia Lake، groundwater quality in some areas of its coastal alluvial aquifers has been significantly deteriorated. Due to existence of evaporative geological formations، the remaining brine from the Urmia Lake and high evapotranspiration in the region، identifying the source of changes in groundwater quality is difficult in this area. In this research، it has been tried to evaluate the factors affecting the degradation of the quality and salinity of groundwater in the study area by stable isotopes of deuterium and oxygen-18 with some quality and quantity parameters of groundwater. The aquifers in the area are mainly caused by precipitation in the upstream of catchment areas and most likely flood from the melting snow. Therefore، reducing snowfall or changing the rainfall pattern from snow to rain effect on the quantitative and qualitative aquifers significantly in the study area. Exploitation of groundwater resources in the region could have a significant role in reducing the surface water into the lake.