ENGINEERING GEOLOGY
Year:2021 | Volume:13 | Issue:4|Papers Count:7

Artificial stone is a mixture of natural aggregate and additives such as industrial gums (resin), cement and other polymer materials. In this research, artificial stone with additives and two resins (vinyl ester and polyester resin) in order to determine the strength and type of use, mixing plan, 84% rock, 10% resin and 6% additive completely manually without the need Vacuum and pressure system was built. Artificial rocks made with additives (glass fiber, carbon fiber, plastic), and three granite granite stones (Alamut, Sefid Tekab and Nehbandan) are used to determine the physical and engineering characteristics (Brazilian Test, Point Load Test, Uniaxial Compression Test and Ultra Sonic Test) have been tested. Based on experiments, artificial stones made of precious stones, a resin of wilin ester, glass fibers, have the highest compressive strength of single axis and borehole. However, carbon-fiber samples have a tensile strength of 28% compared to glass fiber-reinforced glass samples. The samples made with plastic have the least porosity between the samples of synthetic stones. According to the above results, in environments affected by pressures, high-strength reinforced rocks (glass-fibered samples), in tensile-induced environments; high tensile strength artificial rocks (samples made With carbon fiber) and on sidewalks made of synthetic stones made of plastic due to low porosity.

Shear wave velocity structure of the surficial layer of the earth is one of the requirements in many of site investigation programs. Conventional methods, especially in sites with thick alluvial layers, have limitations for this purpose. In this study, single-station measurement of micro-tremors and surface-wave ellipticity inversion were used to identification of soil structure. The study site is located in the south of Tehran and has a considerable thickness of soft alluvial layers. The ellipticity ratio was obtained using Geopsy software employing the time-frequency analysis method. Due to the uniformity of the subsurface layers of the site, the mean ellipticity ratio curve of the four seismic measurements stations was used to inversion and extraction of the shear wave velocity structure. Due to the uncertainty in the inversion process and to investigate the convergence and stability of the solutions, five different initial models are considered and the inversion process has been repeated 3 times in each model. There is a very little error in inversion results, where they show that the seismic bedrock exists at a depth of about 100 meters. Also, different models have good convergence indicating the reliability of the method used to derive the shear wave velocity structure.

The deformation and failure properties of the loaded rocks are divided into different stages based on cracks' formation and growth. The different damage stress thresholds separate these stages. Considering the damage stress thresholds as a material property, geological properties of rocks can affect the damage stress thresholds. In this research, damage stress thresholds were identified for granite and diorite in the uniaxial compressive loading test with the help of the Acoustic Emission test (AE). Then fluorescence thin sections were prepared from the samples loaded to each damage stress threshold to investigate the effect of the mineralogy and the grain size. The results show that strong minerals increase the stress damage thresholds level due to the high cracking resistance. Furthermore, by decreasing the mean grain size, a better interlocking between the grains is created, and the number of grain boundaries increases. Therefore, the applied force has a higher surface to distribute. Consequently, minerals are less affected by the applied force; their crack density reduces, and crack initiation stress threshold increases.

The advent of new technologies in the field of three-dimensional mapping of outcrops has made it possible to provide precise geometrical information of the rock mass structures to identify and survey discontinuities. This research presents a process where using dense cloud data obtained from digital 3D mapping techniques and by integrating capabilities of some software, the orientation and spacing of persistent discontinuities of rock mass and the volume distribution of rock blocks are calculated. Here, at first, the points belonging to each discontinuity plate are examined by performing the coplanarity test and categorized by statistical methods. In addition, the discontinuities that are perpendicular to the surfaces of rock mass outcrop and the discontinuity plane is not visible were visually identified along their trace line. After identifying the points belonging to each discontinuity sets, points were clustered according their spatial distributions and a single plane fitted to the points belonging to each cluster. So, all visible discontinuities in rock mass, by the assumption of persistent, were geometrically simulated. On the other hand, a volumetric 3D model of rock mass was created using point cloud data. By geometric combination of generated joint planes and volumetric model of rock mass, rock blocks were created and block volume distribution diagram was obtained. In order to validate the method presented here, a geometric model with orthogonal regular joint system with accurate analytical solution was applied, and also the results were compared with the previous block volume estimation methods.

The stability of underground mining spaces and the analysis of stresses and deformations created after explotiation have a particular importance in underground mine designe. Anguran lead-zinc mine is located 125 kilometers southwest of Zanjan city and according to the plan, at least 12, 000 tons of ore will be extracted from underground section of it. this research investigate the stopes stability of 2741 level in underground Angoran mine in order to obtain appropriate dimensions of stopes and to provide the necessary support using Phase2d V8 software. For this purpose, in both sulfur and oxidized ore zones, different dimensions and supports of the stopes are determined by comparing the displacements around the stopes with the critical and permissible strain values calculated from the Sakurai relations. The results of the analyzes based on the input data indicate the appropriate stability condition in the sulfur ore. The impact of pillar in sulfur ore was investigated for two widths of 5 and 10 m, and the results showed that in both cases, the stopes were stable without support system. But due to discontinuities in the roof and parts that are mixed with sulfur and oxidized, a support system is needed. In oxidized and mixed ores, the support system should be used because of the poor properties of the rock the dimensions of the pillar.

As part of the stabilization systems for excavations and slopes, shotcrete today plays an extensive role in civil and mining engineering practices. A great number of efforts have been made during recent years to improve the strength and ductility of shotcretes. Fiber incorporation can be named as one of these efforts. Based on the type and characteristics of fibers, reinforced shotcretes display different properties. As a result, advantages and disadvantages of each type of fiber are being studied. This study presents the results obtained from experimental investigations of the influence of waste tire textile fiber addition on strength, ductility, and energy absorption capacity of shotcretes. After preparing specimens reinforced at fiber contents of 0. 5%, 1%, 1. 5%, and 2%, unconfined compressive strength, Brazilian tensile strength, and three-point bending strength were conducted on all samples. The results show that using the fibers inhibits the brittle behavior of specimens and increases energy absorption capacity. Several advantages of using this fiber can be named such as high entanglement in the matrix, low specific weight of the fibers as compared with mesh and steel fibers, easy pumping, and high durability in damp and acidic environments. Moreover, due to the fact of being waste materials, using these fibers leads to lowering the costs of projects as well as tackling the environmental hazards ensued by burying or burning them.

Probabilistic slope stability analysis provides a tool for considering uncertainty of the soil parameters in design. In this paper, using Slide software, the Monte Carlo simulation is used as an analytical method to develop probabilistic models of slope stability based on equilibrium methods. The limit equilibrium methods are the most popular approaches in slope stability analysis. These methods are well known to be a statically indeterminate problem, and assumptions on the inter-slice shear forces are required to render the problem statically determinate. In modeling using this methodology, the selected stochastic parameters are internal friction angle, cohesion and unit weight of soil, which are modeled using a truncated normal probability density function (pdf). In this research, the abilities offered using models were presented by using field data obtained from Roudbar Lorestan dam in Iran. The results obtained show that the hybrid Monte Carlo simulation and equilibrium methods can be used successfully for slopes stability assessment.