Experimental modeling of segmental shallow tunnels in alluvial affected by normal faults

• The details of nine centrifuge modeling of a normal fault and segmental tunnel have described.
• The changes in overburden and angle of fault on tunnel behavior have examined.
• Failure in the segmental tunnels caused by normal faulting is not sudden.
• The length of the tunnel affected by faulting decreased as the overburden increased, but the severity of damage increased.
• It is possible for a sinkhole to form on the surface of the ground as the soil collapses into the tunnel.

Faulting is one type of permanent ground displacement and tunnels are at the risk of damage from faulting because of their long lengths. There are few studies that examine the behavior of tunnels intersecting the fault zones although it is of continuing concern for design engineers. Determining the failure mechanism provides critical information for the design of a tunnel, including its segmental lining. The present study conducted a series of centrifuge model tests on segmental tunnels subjected to normal faulting. The results indicated the absence of sudden failure of segmental tunnels under normal faulting and improvement of function in response to an increase in the overburden of the tunnel. The angle of the fault affected tunnel behavior. Despite large displacement faulting, structural damage to the segments was very low because of the adequate geometric functioning of the segments and their joints. The length of the zone affected by faulting in the tunnel decreased as the overburden increased, but the severity of damage increased in response to localization of fault displacement. Sinkhole formation upon the collapse of soil into the tunnel is likely at the ground surface. Special attention must be paid to the effect of sinkholes on at ground structures in the vicinity of the tunnel.

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