فهرست مطالب کریم روشن بخت

Bio-improvement has been identified as an environmentally friendly method, Microbially Induced Calcium Carbonate Precipitation (MICP) is the predominant technique in this domain. The four main methods introduced for MICP are the injection, surface injection or flow-through, immersion, and mixed methods. Among these, the injection and the flow-through methods hold particular significance. In this study, the efficiency and performance of these two methods were investigated in soils with different relative densities and varying volumes of bacterial suspension injection.To assess the efficacy of these methods, various tests including optical density, urease activity, permeability, uniaxial strength, calcium carbonate pericipitation percentage were conducted. The flow-through method, with its easier implementation, absence of the need for special equipment, minimal reduction in permeability, more uniform dispersion of the resulting cement, and the ability to achieve comparable strength to the injection method when using an injection volume equal to the pore volume in high relative density, stands out as the more suitable and economical approach for improving sandy soils. Despite its cost-effective implementation, the flow-through method necessitates more injection cycles, particularly in the injection volume of two-thirds and one-third of the pore volume, to achieve the same strength as the injection method. This aspect diminishes the economic difference between improvement using the injection method and the flow-through method in laboratory. This aspect diminishes the economic difference between improvement using the injection method and the flow-through method in a laboratory conditions.

Engineering Geology and geotechnical parameters assessment is of the most important issues in successful tunnel design and construction operation. In urban areas, exact and complete reconnaissance of these parameters and site investigations are more critical as a result of the intensified effect of settlement and failure of the tunnels. Geotechnical parameters and hazards in tunnel route also affect the tunnel boring machine (T.B.M) selection and so they are challenging and very important issues. Shahid Motevasselian tunnel with a length of 10 Km. connects Shahid Sayyad Shirazi highway south wards (from north of Sepah Sq.) to Azadegan highway. There is a high geological diversity in geological units as a result of North- south direction of the tunnel and so it is too complicated to assess the parameters. In this study, as a good experience, the method of dealing with the complexities to achieve a reliable assessment of geological and geotechnical conditions is considered and also the possible hazards in different parts of the tunnel is determined. According to the geological and geotechnical situation, tunnel rout is divided to 3 distinct parts (northern part, middle part and southern part) and introducing the different soil types in terms of Geotechnical parameters, range of different parameters in any soil type is determined by combining the results of field and laboratory investigations, and finally, the material properties of each soil type determined as well as possible hazards likely in different parts of the tunnel route.

Selecting a suitable tunnel boring machine is one of the most important issues in mechanized tunneling in urban environments. Factors such as geological and geotechnical conditions of the tunnel route, groundwater condition, costs, technical and environmental factors are important factors affecting the selection of TBM in urban tunnels. The Motevaselian tunnel with a length about 10 km is located along the Sayyad Highway from the north of the Sepah Sq. to Azadegan highway. Due to the north-south direction of the tunnel route, in terms of geological and geological conditions, there are a wide variety of geological units. According to the geological conditions, the tunnel route is divided into three parts: north, middle and south, which have different conditions for TBM selection. This has caused some complexities in the choice of TBM type. In this paper, it is tried to investigate geological and geotechnical conditions and also consider other factors affecting the operation of tunneling machines and then to propose the most suitable TBM for tunneling based on the methods and guidelines for selection of the machine. Therefore, using multivariate decision making criteria, analyzes in different scenarios were performed. For the whole tunnel route, in addition to the geotechnical aspects, regarding the cost factor and environmental-technical factors, EPB machine was selected slightly well than Slurry machine.

Microbial-induced calcite precipitation (MICP) is a relatively green and sustainable soil improvement technique. It refers to a chemical reaction network that is managed and controlled within soil through biological activity and whose byproducts alter the engineering properties of soil.To treat soil, first, the microbial population in-situ is augmented by the injection of additional urease positive bacteria and then reagents are added. This paper provides an overview of the factors affecting the MICP in soil. Several factors including nutrients, bacteria type, geometric compatibility of bacteria, bacteria cell concentration, fixation and distribution of bacteria in soil, temperature, reagents concentration, pH, and injection method are introduced. These factors were found to be essential for promoting successful MICP soil treatment. Furthermore, a preliminary laboratory test was carried out to investigate the potential application of the technique in improving the strength and impermeability of a sand specimen and utilized techniques, materials, methods and empirical process during the test are explained. The results showed that as a result of the calcite precipitation, shear wave velocity increased up to 1000m/s and UCS strength increased to about 300Kpa and permeability of soil decreased significantly upon MICP treatment.

We use high-resolution electrical resistivity imaging to delineate the geometry of the landslide and discontinuity surface between slide mass and bedrock in Roudbar region, Ghazvin-Rasht-Anzali railway (the tunnel no. 2 at Km. 108+825). The Roudbar region characterized by high geological hazard and shows a complete panorama of mass movements. In this area, different landslide types predisposed and tightly controlled by the geostructural characteristics. Geoelectrical images are produced from dipole-dipole, schlumberger and combined resistivity profiling data along arrays spanning selected profiles positioned perpendicular and parallel to the tunnel route in landslide area. Regarding the surface geology, geomorphology, integration and comparison of dipole-dipole results with other geophysical data delineated the geometry and characteristics of the landslide and geological structures.