Seismic behavior evaluation of drilling foothills’ effect on tunnel maintenance system using numerical modeling

ABSTRACT: Dynamic stresses caused by seismic waves are added to static stresses existing in tunnel lining or underground space and its surrounding rocks. Increasing stresses raise the probability of crushing and peeling state in underground space environment. Seismic stresses decrease static in-situ stresses and increasing it can cause slip, relocation or even structural failure. In this article inductive effect of drilling foothill under horizontal quasi static force on an existing complex tunnel maintenance system in foothill has been studied. Thus by the use of Phase2 software, a finite difference method, a domain at 45 degree slope and 100 meters height has been modeled, where a tunnel with diameter of 10 meters has been drilled. Results indicate that values of axial forces and axial stresses in rock bolt are increased due to drillings in foothill under quasi static force. Values of axial forces, bending moment and shear-stress maintenance cover, show a considerable increase. These issues indicate the importance of seismic design and its high effect on underground space endurance and stability.