Investigating Effect of Tunnel Gate Shapes with Similar Cross Section on Inserted Forces on Its Coverage and Soil Surface Settlement

According to technology development and relative facilitation in digging and underground structures, ways, highways, all types of tunnels, underground train network, and other underground settle, storage are number of structure built and developed in advanced countries. In most situation, tunnel digging operations are done years after its construction or are not recorded in new structures regulations;therefore, this research investigates soil settlement and inserting force to tunnel coverage by limiting studies about effects of tunnel shapes on soil settlement using Plaxis, Seismo Signal, and Seismo Aspect. This study shows that rectangular tunnel has the most settlement in soil surface and circular tunnel has the least settlement but horseshoe tunnel has similar behavior to circular tunnel;however, earth subsidence level by digging this tunnel is more than circular tunnel. In addition, sectional shape has direct effect on inserting forces on tunnel coverage.

Alteration of Ground Motion Acceleration at Ground Level Due To Tunnel Excavation

Underground tunneling is one of the alternative solutions to diminish traffic congestion in large cities. One of the most important effects of tunneling is the displacement of the ground surface, the settlement around the tunnel, and the variation in earthquake acceleration. The performance and behavior of underground structures have been studied by several researchers, but the impact of tunnel excavation on earthquake records and its effects on structures above the ground level have received less attention. This research emphasizes changes of earthquake acceleration at the ground level, structural response and Fourier spectrum by excavating a horseshoe tunnel. Results show that digging a horseshoe tunnel will change the characteristics of the earthquake record at ground level.

Geo-Grid Combined with Concrete and Limestone Columns to Reduce the Embankment Subsidence Located on Inclined Layers of Soft Soil

Soft soil has low shear strength and its density is high;construction of embankments on them would cause problems such as large and non-uniform subsidence. One way to avoid these subsidence is using of geo-grid combined with cement and lime columns. Geo-grids due to their tensile strength, and cement and lime columns due to their bearing capacity and their body friction, reduce embankment subsidence. Extensive researches have been done in order to reduce the subsidence of the embankments located on the roads, but few studies have being done about the inclined embankments on soft soil layers. In this paper, the road embankment has been located on inclined soft soil layers;the study will try to reduce embankment subsidence and uniform them using geo-grid combined with cement and lime column subsidence. The results show that the realization of this issue will cause subsidence reduction and uniformity in the embankment surface.

Impact of Soil Type Used in Tunneling on Land Subsidence and Mobility Effective Time under Different Earthquake Records

During recent decades, tunnels construction in urban environments has been recognized as a useful factor in improving transportation situation in cities. Construction of underground structures like tunnels has a direct impact on the above-ground structures. The most important impacts are soil crust movement of the structure movement), acceleration change of the earthquake on structures, and land subsidence. The present research aims at seismic evaluation of the effect of soil type in land subsidence and effective mobility time in tunneling projects. For this purpose, two different soil types are chosen to model and assess factors using numerical methods. The outcome of this research concludes that tunneling changes in the dominant frequency record if these changes reach to the extent that structure frequency equals to record frequency, resonance phenomenon happens.