دانلود رایگان مقاله انگلیسی تاثیر طراحی لرزه ای در تونل های داخل سنگ - تاریخچه موردی - الزویر 2017

Abstract

The tunnel industry has considered that tunnels, especially tunnels in rock, are naturally resistant to earthquake action, including faulting, shaking, deflection and ground failure. As the number of case histories of tunnels subject to earthquake action has increased, the industry has started to recognize that, although tunnels in rock have good resistance against earthquakes generating peak ground accelerations (PGA) lower than 0.5 g, it is important to include the dynamic forces and displacements generated by seismic ground motions in the design process to obtain a more reliable design. These additional earthquake forces impact the final design, potentially requiring changes to the ground support and additional reinforcement of the concrete lining, as illustrated by case histories presented in this paper.

Conclusions

This brief review of literature and review of specific case histories the author has been involved in indicate that tunnels in rock generally are capable of withstanding moderate earthquake events without the need to modify their designs. However, to increase the reliability of the tunnel structure and to accommodate larger events at closer distances, it is necessary to consider the effect of the dynamic loads generated by earthquakes. Future research on the impact of earthquakes on the ground support is necessary to obtain more reliable tunnel designs. Many tunnels are left unlined so in case of earthquake there is no second line of defense (final lining), and the current general objective of the ground support design is efficiency, both minimizing the materials needed and the time required to install them. It is clear from the case histories presented that the ground support is adequate to maintain the tunnel opening stable in static conditions, but larger seismic events (PGA > 0.2 g) can cause failures of the ground support. Additional research on the role of groundwater on the behavior of tunnels during seismic events is also necessary.