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pore water pressure to reduce the cohesion within the soil particles. All these as a
whole, affect the slope stability. At Tindharia Proper, 14 miles Bustee, Nurbong T.
E., Central part of the Basin, Shiviter T.E. the angle of rupture is 33
°
,34
°
,34
°
30
°
32
respectively (Table
6.2
, Figs. F.1, F.2, F.3, F.4, F.5, F.6, F.7, F.8,
F.9, and F.10, Appendix-G). The geotechnical parameters of the soil from different
locations of the Shivkhola Watershed are represented in the following developed
Mohr Stress Circles which depict the visible interpretation about the strength of
slope materials (Appendix-G, Figs. F.1, F.2, F.3, F.4, F.5, F.6, F.7, F.8, F.9, and
F.10).
°
and 34
°
15
′
6.5.2 Stability Analysis Based on Safety Factor for 10 Major
Landslide Locations
A stability analysis has been made on the basis of the calculated Safety Factor
s
value (Table
6.3
) from various sites of the Shivkhola watershed which reveals that
most of the sites such as Tindharia, Lower Paglajhora (14 miles bustee), Lower
Paglajhora (main slide), Tindharia Railway Station, Shiviter, Sepoydhura, Nurbong
T.E. and also the mid-section of the Watershed are registered with the Safety
Factors value of less than 1 and it can be assumed that the slope materials of all
these places are under stress and instable in nature. Remaining soil sample analysis
sites (Mahanadi and Gayabari) are attributed as Quasi Stable part.
'
6.5.3 Comparative Stability Analysis Between Dry,
Semi-saturated and Saturated Soil Condition Based
on 1D Slope Stability Model
The shivkhola watershed exhibits a wide range of elevation (300
2,400 m). Slope
-
ranges between 7
. The central middle section and lower section of the
watershed is attributed with very gentle slope gradient of less than 20
°
and 65
°
whereas
marginal part and extreme north, south and west are characterized by very steep
slope of more than 50
°
°
(Table C.1, see Appendix C). Generally, slope materials having coarse grains over
the steep slope shows friction friction angle than the materials with
°
. Angle of internal friction varies between 18
°
and 33
finer particles
deposited along the foothills zone. At Lower and Upper Paglajhora, Tindharia
Upslope, Shiviter and Nurbong the friction angle and cohesion of the soil is very
low. Cohesion of the soil is high in the mid and lower part where more than 50 %
particles are composed with
finer particles.
field work at 50 sites in the basin reveals that depth of soil varies
from 0.45 to 3.75 m in the Shivkhola Watershed. The central mid-section and lower
part of the watershed are registered with maximum soil depth whereas marginal part
The intensive
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