The area of Subansiri lower dam comes under heavy rainfall region plus it has large number of highly fractured rock which lead to buildup of pore water pressure. This buildup of pore water pressure and the area comes under high seismic zones, therefore there is high chances of failure of slope. The slope near Subansiri Lower Dam was needed to be protected for protection of power house because slope on that area was constantly under high stresses generated due to flood which will lead to instability of slope. The work of slope protection is entrusted to Geo Spar Infra Pvt Ltd.
Solution suggested by us:
The Geo Spar is carried out survey on the location for collecting data for conducting analysis, by carrying out analysis it is found that anchors of 120 ton capacity is perfect for counter active earth pressure generated. Design and Installation of Wire Anchor of 120 Ton Capacity for Slope Protection of Power House. Geo Spar Infra Pvt Ltd design engineers designed anchor system by generating 2 dimensional modelling of the slope and analyzing it for different trails. The anchor system with 2 layers of anchor of 32 meter length out of which 7 meter bond/fixed length with 3×3 meter spacing and the inclination of anchors with horizontal 100 is found to be stabilizing the slope. Stressing of the anchor is done after 21 days and locked off at 110% capacity.
The anchors are installation is now executed by Geo Spar execution team as per the design. The anchor installation for protection work of light house is to be done at elevation of 120 and 123 meters. Our execution team is enriched with professionals having vast experience and with highly advanced machines enables the Geo Spar to carry out protection work on time without fail.
Difficulties faced while execution:
The slope protection work required scaling and removal of loose material first followed by benching. The benches individual stability was also an important factor to keep in mind because sometimes even the bench get washed out due to heavy rain. The rainfall causes the water to percolate from back of the slope which cause problem in setting of grout at fixed length of anchors due to which grouting have to be done for the fixed length again and again.
Extra Technology used for execution:
The strata present in the site is a variable and collapsible strata in which drilling of casing is a big task so we imported Casagrande machine for drilling of casing. Adopted special type of admixtures for the fixed length portion to get faster strength and accelerated setting.
The power house is located at steeper slope and there is heavy rains in regular intervals which increase pore water pressure and generates active earth pressure. The slope protection work performed by Spar Geo Infra Pvt Ltd for light house protection is remained intact even after regular rainfalls.