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        1 - A Parametric Study of Interactions Between Liquefaction Sand Lenses and Shallow Tunnels Under Earthquake Loads
        Mohammad Shabani Soltan Moradi Mohammad Azadi Homayoon Jahanian
        If the saturated sand lenses are placed around the tunnels under the force of the earthquake, liquefaction will occur in them. This will cause settlement of the ground surface and changes in forces and anchors on the tunnel lining. For this purpose, it is important to e More
        If the saturated sand lenses are placed around the tunnels under the force of the earthquake, liquefaction will occur in them. This will cause settlement of the ground surface and changes in forces and anchors on the tunnel lining. For this purpose, it is important to evaluate the change of different parameters of the sand lens and the change of the thickness of the tunnel lining in the part of the sand lens and the changes in the diameter and depth of the tunnel as well as the location of the sand lens considering the tunnel inside it. Therefore, this article investigates the mentioned changes in shallow tunnels in the location of sand lens in flowing soils surrounded by clay. In this article, FLAC 3D software is used to determine changes in pore water pressure and effective stress reduction after sand lens liquefaction. Based on the obtained results, if the sand lenses are placed at a depth of less than 10 meters, they increase the land surface subsidence by 36% compared to the reference model B, with an increase of 2 meters in the depth of the sand lens compared to the reference model B, the value of the maximum bending anchor and axial force on the tunnel lining increases by 35.7% and 14.4%, respectively, in the sand lens part. The findings of the present study can be very useful in the decision-making process of tunnels that are dug inside flowing sand lenses. Manuscript profile
      • Open Access Article

        2 - Assessment of Soil cohesion of Soils on Tunnel Excavation
        Mohammad Azadi
        Excess pore pressure under seismic loadings has always been a main concern in geotechnical engineering practices. Undergoing the phenomenon in a soil can cause the effective stress and hence the shear strength of the soil to decrease considerably and large deformations More
        Excess pore pressure under seismic loadings has always been a main concern in geotechnical engineering practices. Undergoing the phenomenon in a soil can cause the effective stress and hence the shear strength of the soil to decrease considerably and large deformations happen in the area. Generally, increasing the pore pressure occurs under the undrained condition. If it can be formed the drain conditions, its consequences decreases seriously. The damages caused by Excess pore pressure are divided in to two groups, surface damages and underground structures damages. Generally, first case is visible after the seismic loadings about which wide researches have been carried out. But in the second group, the lack of these occurrences and investigation problems cause the underground structures damages to be assessed less. There are several reports on devastations caused by excess pore pressure in the surrounding soil of the underground structures. As stresses and deformations of the tunnel lining increase, the surrounding soil of the tunnel is liquefied and large deformations are observed in the area. And if increasing the pore pressure occurs in the surrounding soil of the tunnel, improvement of the surrounding area of the tunnel, the stresses and deformations should be controlled to be set on the allowable limit. Therefore, evaluation of excess pore pressure effects on the tunnel lining can be regarded as an important issue. This paper is designed to focus on the topic. Manuscript profile
      • Open Access Article

        3 - Assessment of the Drain Conditions on Variations of the Pore Pressure in Surrounding Soil of the Tunnel
        Mohammad Azadi Azadi S.M Mir Mohammad Hosseinib S.M. Nasimifar M Pouranian
        Excess pore pressure under seismic loadings has always been a main concern in geotechnical engineering practices. The phenomenon in soil can cause an effective stress and hence cause the shear strength of the soil to decrease considerably and large deformations to occur More
        Excess pore pressure under seismic loadings has always been a main concern in geotechnical engineering practices. The phenomenon in soil can cause an effective stress and hence cause the shear strength of the soil to decrease considerably and large deformations to occur in the area. Generally, increases in pore pressure occur in un-drained conditions. If it is formed, its consequences decrease seriously. There are several reports on devastations caused by excess pore pressure in the surrounding soil of the underground structures. As stresses and deformations of the tunnel lining increase, the surrounding soil of the tunnel is liquefied and large deformations become observable. If an increase in the pore pressure occurs in the surrounding soil of the tunnel, which is an improvement of the surrounding area of the tunnel, then stresses and deformations should be set on the allowable limit. Therefore, evaluation of excessive pore pressure effects on the tunnel lining can be regarded as an important issue and this paper is designed to focus on precisely this topic. Manuscript profile
      • Open Access Article

        4 - The Effects of Shallow Tunnels on Nearby Structures
        Mohammad Azadi A. Zahedi
        Nowadays, underground structures play vital role in developing different countries. Such structures are constructed in many civil activities such as development of road and railways, subways, water, gas and sewage lines, underground subways, nuclear wastes land filling, More
        Nowadays, underground structures play vital role in developing different countries. Such structures are constructed in many civil activities such as development of road and railways, subways, water, gas and sewage lines, underground subways, nuclear wastes land filling, fuel storage and military installations. With an appropriate drilling method being selected, instabilities created in tunnels may be controlled, the volume of maintenance systems required in structures may be decreased, and extra costs arising from it may be decreased as well. Excavation of surface tunnels may bring about changes on the surface and in the adjacent structures. Settlement on the surface and instabilities in adjacent structures as a result of stress induction are among the most important changes of this kind. Plaxis software has been used in the research to evaluate the technical parameters of tunnel such as tunnel diameter, tunnel depth from the earth surface, drilling method and distance from adjacent structures. Meanwhile it investigates the effects of urban tunnel drilling as lifelines on adjacent structures and render the results in the form of a diagram. Manuscript profile
      • Open Access Article

        5 - Assessment of Subsurface Explosion caused byTunnel Construction in Urban Areas
        Hossein Haghighimanesh Mohammad Azadi
        Nowadays, tunneling in urban areas is a common activity for a variety of transportations such as subways, water supply, lifelines andsewers that may require blast operations. The characteristics of stress waves of the blast are quite different from earthquake waves. The More
        Nowadays, tunneling in urban areas is a common activity for a variety of transportations such as subways, water supply, lifelines andsewers that may require blast operations. The characteristics of stress waves of the blast are quite different from earthquake waves. The blast waves are usually of high frequency content, short duration, equality of amplitudes in horizontal and vertical directions and large range of magnitude from ten to thousands of the gravitational constant. However few papers can be found to discuss about the effect of soil characteristics under blast loading. In this paper, numerical models based on finite element method is used to simulate stress wave at soil sites under explosion effect in an underground linear chamber and then characteristics of the ground movement and the explosion effect on soil-structure interaction is analyzed. In this study, numerical results of area deformations in every region are compared together and parameter sensitivity of the soil is analyzed. Results presented in this paper can be used in a more detailed assessment of ground motion effect on structures. Manuscript profile