Landslide Mitigation - Semi-quantitative Approaches for Landslide Assessment and Prediction - page 234

Fig. 8.8 Retaining wall at
lower Paglajhora

out of the seepage water from the slope materials which can reduce the pore-water
pressure and can check the landslide.
Interruption of drainage from the back

fill is the main cause of failure of
retaining wall and which is generally observed at Shiviter (Fig. 8.7 ), Paglajhora and
Tindharia. The loose clay and silt are generally drained with water and helps in
clogging the weep holes. Only the retaining wall could not be able to manage such
slope failure. Here, Shotcrete technique, a soil-cement mixture that can be sprayed
above the retaining wall (open surface) to prevent erosion from weathering and
percolation of rain water. The steep slope of the massive slope failure section of
14 Miles Bustee would be shaped and reduced and then retaining wall may be
constructed with full care.
For the shallow debris slide (Fig. 8.7 ) on the way to Shiviter Tea Garden Gabion
Mattresses, a rectangular basket made up of wire mesh that are filled with small

rocks built by hands, can be laid end to end and side to side on the slided scar with a
fairly solid foundation. Several gabion mattress can be joined together to prevent
soil erosion and slope materials failure. Before the placement of the gabion mattress
the slope has to be well prepared and a

filter layer is placed beneath it to resist the

movement of finer particles entrainment from the sub-surface soil that can improve

the soil strength. Sometimes the weight of the retaining wall is so high so that
additional stress cannot be resisted by the slope and thus entire slope moves down
slope. The bamboos net are

fixed at regular interval to restrict the down slope
movement of dislodged materials. The thrust from the back ll is so high so that

these bamboo structures are damaged (Fig. 8.9 ). The introduction of vegetation on
the slide scar at the back fill of each bamboo structure in a process of developing

total green cover may be an effective management on suitable slope.