TUNNELING & UNDERGROUND SPACE ENGINEERING
Year:2016 | Volume:4 | Issue:2|Papers Count:7

Social assessment is process of preparing framework to prioritize, collecting, social information analyzing and classifying, participation in design and provision of urban development operations. Unforeseen consequences of urban development projects can greatly reduce the project benefits, so from this point, social impact assessment is important. Since this issue has been less attention in the country development projects, in present study evaluating social impact of Hakim Highway Twin Tunnels construction projects in Tehran metropolitan, studied by quick matrix method. In this method according to each plan, consequences and their impact on the social environment have been rated and finally, assessment is done on the basis of rates. The results show that most negative consequences in construction phase activities of project on social and cultural is related to traffic by low intensity. Consequences in operation phase of the project, on the social and cultural tasks, are +74. The most positive effect is related to reducing traffic with high intensity.

Design of support system is One of the most important issues in tunnels design. Therefore, in order to safe design of support system, determination of internal loads has a special importance. In this paper, analytical and numerical methods were used to determine of internal loads, and in 2D and 3D states, the results of these methods were compared with the assumption of no slip and full slip conditions. Findings prove that in different sections of support system, the axial force obtained from full slip condition is more uniform than that of no slip condition, and the bending moment of full slip condition is higher than that of no slip condition. According to results, an increase in stiffness contrast between support system and ground results in an increase in the internal loads. Moreover, by increasing of the tunnel radius, the bending moment decreases and axial force increases.

The total number of EPB-TBMs that were utilized for tunneling between 2005 and 2010 is approximately 350 units worldwide. One of the most critical adverse conditions is encountering abrasive soils and excessive wear on the cutting tools and the cutter head as has been reported in many EPB tunneling projects worldwide. In this project, the number of cutting tools replaced were 1169, including 654 rippers, 357 scrapers and 153 disc cutters. In this paper the influence of geological parameters and operational factors on tool wear is studied. The objective of the current study was to investigate tool wear on EPB machines through a case study and field measurements. This refers to assessment of the fundamental reasons for increases of TBM tool wear in certain ground conditions to find a correlation between geological conditions and operational parameters with cutter life in soft ground tunneling. This paper introduces the subject tunnel project in this case study, describes the Cutter life parameters as observed in this project and presents results from TBM operation’s and soil properties and their influence on tool wear. The results of this study show that by increasing TBM thrust, earth pressure and torque, the cutter consumption generally increases. Also, soil conditioning plays an important role in controlling cutter wear, so that the tool wear can be reduced even in coarse-grained soils by improving the soil conditioning parameters.

Any physical problem can be explained by the mathematical model. Most of those models are partial differential equations. The mechanic behaviors of rock mass around any underground structure can be defined by partial differential equations. By solving this equation, the stresses and deformations around the tunnel can be calculated. The stability of tunnel can be defined by using the calculated stress concentration around tunnel. In this paper the stress concentration around the square tunnel is obtained by the analytical solution and using complex potential equations. The square cross-section of tunnel transfer to circular one by the method of conformal mapping. Here the rock mass considered elastic and isotropic. The results show, with increasing the components of mapping series, the tunnel surface becomes smoother. Also for the above cases, the tangential stress around tunnel increases.

Today, with advances in technology, enable the design and construction of accurate underground structures are provided. Nevertheless, the analysis of underground structures due to interaction between the soil or rock surrounding infinite medium and tunnel supporting system, is very complex and then lower research is done.Introduction: The response of tunnel supporting system under seismic loads is a function of the ratio flexibility of the lining and rock or soil medium. This ratio represents the stiffness difference between the ground and tunnel lining. And in fact, the interaction of the tunnel lining and medium is indicated.Methodology and Approaches: In this paper, two analytical methods for investigating the underground spaces behavior under seismic loading is presented. Then, the response of tunnel monolithic lining in no-slip and full-slip conditions with using analytical and numerical methods with considering of interaction between tunnel lining and medium is investigated.Results and Conclusions: The results showed that the stress induced by seismic loads in tunnel lining in no slip condition is 2.7 times higher than in full slip condition. Also, monolithic lining strain value in full slip condition is further than no slip condition.Results of numerical method shows good agreement with analytical methods.

Underground tunnels, particularly, have distinct seismic behaviour due to their complete enclosure in soil or rock and their significant length. Therefore, seismic response of tunnel support systems warrant closer attention. The geological settings in which they are placed are often difficult to describe due to limited site investigation data and vast spatial variability. Therefore, the parameters which govern the design are many and their variabilities cannot be ignored. A solution to this issue is reliability based analysis and design. These real conditions of variability can only be addressed through a reliability based design.Introduction: The concepts of reliability has been less considered by the researchers in the engineering analysis and design of tunnels and underground spaces. Laso et. al (1995) studied the reliability in the designing of tunnel lining. Quing Lu et. al (2013) evaluated the reliability of the rock tunnels with respecting to several statuses of rupture mode. The studies conducted on the reliability of tunnels, mostly ignored the seismic design parameters as well as the consideration of reliability in the parameters of the surrounding tunnel soil.Methodology and Approaches: In this research, response surface method (RSM), the reliability concept of Hasofer-Lind and finite element method (FEM) are composed in order to investigate the reliability of the lining of shallow underground tunnels. For this purpose, an underground tunnel with the height of 5m has been subjected to 7 earthquake records using finite element software ABAQUS. The random variables considered for surface response method are soil dynamic elasticity module, cohesion and internal friction angle of the soil. The reliability index has been approximated for axial force, flexural moment, shear force and displacement of tunnel by conducting trial and error tests on the three mentioned parameters.Results and Conclusions: The results obtained in this research are briefly summarized as follows: The reliability index value is lower in the tunnel lining under seismic loads for all obtained responses, comparing to those under static loading. In the other words, the reliability of soil and tunnel systems are reduced concerning the random nature and criticality of loading as well as randomness of soil parameters.The reliability index values are lower for the shear force response of the tunnel lining under Earthquake records, comparing to those of axial force and flexural moment. Consequently, it is recommended to retrofit the whole soil under earthquake loading against shear cracking.