DESIGN OF ROCK ANCHORS IN ELLIPTICAL CAVERN ROOF SUBJECTED TO SEISMIC FORCES AND PORE WATER PRESSURE

Abstract

Determining the length and pre-tensioning force of rock anchors is a difficult task as very few studies have been done on this topic. Using the upper bound theorem solution of the failure surface of the roof of the elliptically shaped tunnel considering the pore water pressure and seismic forces is developed. Considering an elliptical roof subjected to the mentioned forces the required length and pre-tensioning force of anchor cables is derived using the principle of virtual work, based on Hoek-Brown criterion. The rock strength parameters of Lakhwar Dam project tunnel are taken to show the variation of the length and pre-tensioning force with different parameters on which it depends. The most influential parameter for the length and pre-tensioning force is derived.