ROCK MASS CLASSIFICATION ALONG PROPOSED HRT

S.No Rock Type Length in (m) Approx. %age w.r.t. Tunnel Length Groundwater probability RMR Values Class of rock % Remarks
I II III IV V
1. Schistose Quartzite with subordinate bands of Biotite Schist. 3600 12.0 Interstitial water seepage 43 to 78 8 3 1 Schist bands thickness varies from few cms to 2m. Gneiss band of about 100m thickness.
2. Biotite schist with subordinate bands of schistose Quartzite 5290 17.0 Dry to dripping 40 to 60 15 2 Frequency of shearing expected relatively more. A band of carbonaceous phyllite is apprehended within this unit.
3. Carbonaceous Phyllite, phyllite and phyllitic schist (Garneti ferrous) 1060 3.0 Interstitial water seepage 1 2.0 Upper & Lower contacts expected to be more shattered.
4. Quartzite with subordinate bands of chlorite schist 11440 37.0 Generally dry to dripping, at places moderately inflow. 65 to 75 & rarely 80 & 40 3 24 5 5.0 Quartzite-granite contact expected to be associated with talcose band of 10-20m thickness.
5. Talc chlorite schist 140 0.5 Moist 0.5 Thinly foliated rock with soapy feeling.
6. Granite/Gneissose, Granite/Granitic gneiss with intermittent bands of Metabasics and chlorite schist. 8820 28.0 Dry to dripping with Moderate inflow at places. 63 to 85
Rarely < 60 5 20 3 Concordant bodies of metabasic & chloritic schist (1 to 10m) expected intermittently at an interval of 500-700m.
7. Metabasics with intermittent bands of chlorite schist. 880 2.5 Moist to dripping with low to moderate inflow at places 52 to 67 with pockets of low values 1 1.5 Metabasic-quartzite contact is sheared/faulted and intermingled.
TOTAL 31230 100.00 8 52 27 9 4