Stress and deformation analysis of powerhouse cavern of Rasuwagadhi hydroelectric project, Rasuwa, Central Nepal

Abstract

An underground powerhouse cavern of Rasuwagadhi
Hydroelectric project lies in Bhotekoshi River, northern part of
Rasuwa, Central Nepal. Letter box shaped cavern of maximum
dimension 76.6 m in length, 15.3 m in width and 39.65 m in
height is situated at the depth of 320 m with its longitudinal axis
of east to west. Geologically, the area belongs to the rock of the
quartzite with intercalation of dark grey schist of Higher
Himalayan succession. To determine different properties unit
weight, point load strengths of rock samples were done for the
model analysis. The rock mass properties based on GSI were
recorded in different chainage of cavern. By using various
geotechnical property, and numerical methods deformation
analysis of cavern was done. The analyses were carried by
using 3-Dimensional and 2-Dimensional numerical modeling
from Examine3D and Phase2 softwares and then the modeling
result were compared with the instrumented data from multi-point
borehole extensometers. The deformation from both numerical
model and instrumental data showed similar results