Geotechnical Investigation works for the work Construction of Perimeter road ic Slope Stabilization work (Western Side) from CH. 920 to 1970 mtr and Shifting of Perimeter Fencing at Pakyong Airport, Sikkim

Amount

Site reconnaissance for collecting data about site nature, topography of the site, geological features, Rock types and other properties concerning the project site. The geological investigations include rock mass classifications; determination of Geological Strength Index (GSI) and Rock Mass Rating (RMR) values for the slope sections of 50 m length parallel to the airport runway both sides from the marked borehole locations on the contour map.

Mobilization of necessary plant, equipment(s) and personnel to the project site, setting up the equipment, shifting of the equipment from one test location to another location, carrying out the field investigations on land and demobilization on completion of work

Drilling at uphill side (Western side, Borehole 1 to 6): Depth of Boring: 50m (at least) with assumption of 5m soil cover. (Locations are provided on site map separately). (a) The geotechnical investigation includes drilling of boreholes, performing SPT as per IS 2131: 1981 (RA 2021) in the boreholes and to collect undisturbed and disturbed sampling from boreholes at 0.75 m interval alternatively in depth or when there is a change in strata, whichever is earlier and relevant laboratory tests . Borehole is to be made at Six (06) locations. Drilling is to be carried out as per IS 1892: 2021 through 150 mm nominal diameter boreholes. (The payment in this item shall be made as per the actual depth drilled till soil cover is encountered and the payment for the balance depth drilled after encountering soil cover shall be made in Item no. 4)

Drilling at uphill side (Western side, Borehole 1 to 6): Depth of Boring: 50m (at least) with assumption of 5m soil cover. (Locations are provided on site map separately). (a) Drilling in hard stratum (rock) is met with (hard stratum is confirmed by either the refusal from SPT or due to resistance during the drilling operation), further drilling is to be carried out by NX core drilling with TC/Diamond bits as per IS 6926: 1996 (RA 2020) by using double core Each run of the core drilling is to be properly recorded. At the end of each run, the drill rod string with core barrel is to be extracted and core is to be recovered. The cores are to be carefully transferred to the core boxes, and properly preserved, numbered, labeled and photographed for reporting. The rock core recovery (C.R.) percentage and Rock Quality Designation (RQD) are to be recorded.

Drilling at downhill side (Eastern side, Borehole 7 to 12): Depth of Boring: 30m (at least) with assumption of 10m soil cover underlain by 20m as soil-gravel-boulder mix/Rock. (Locations are provided on site map separately). (a) The geotechnical investigation includes drilling of boreholes, performing SPT as per IS 2131: 1981 (RA 2021) in the boreholes and to collect undisturbed and disturbed sampling from boreholes at 0.75 m interval in depth or when there is a change in strata, whichever is earlier and relevant laboratory tests . Borehole is to be made at Six (06) locations. Drilling is to be carried out as per IS 1892: 2021 through 150 mm nominal diameter boreholes. (The payment in this item shall be made as per the actual depth drilled till soil cover is encountered and the payment for the balance depth drilled after encountering soil cover shall be made in Item no. 6)

Drilling at downhill side (Eastern side, Borehole 7 to 12): Depth of Boring: 30m (at least) with assumption of 10m soil cover underlain by 20m as soil-gravel-boulder mix/Rock. (Locations are provided on site map separately). (b) Drilling in hard stratum (rock) is met with (hard stratum is confirmed by either the refusal from SPT or due to resistance during the drilling operation), further drilling is to be carried out by NX core drilling with TC/Diamond bits as per IS 6926: 1996 (RA 2020) by using double core Each run of the core drilling is to be properly recorded. At the end of each run, the drill rod string with core barrel is to be extracted and core is to be recovered. The cores are to be carefully transferred to the core boxes, and properly preserved, numbered, labeled and photographed for reporting. The rock core recovery (C.R.) percentage and Rock Quality Designation (RQD) are to be recorded.

Recording the depth of ground water table in all the bore holes if observed up to the depth of exploration during boring work. Groundwater accumulation in boreholes is to be monitored during and after completion of drilling activities

Dynamic cone Penetration Test (DCPT) upto 30m depth or the number of blows exceeds 35 for 100mm penetration whichever occurs earlier at the eastern side as specified in IS 4968 (Part-II) - 1976 (RA 2007) & IS 10042-1981 (RA 2002). The DCPTs are to be carried out at every 20m starting from chainage 900 towards chainage 1700 or as suggested by site engineer.

The in-situ density test carried out at in test pits excavated at regular intervals in between the boreholes from 7 to 12 at depth 1.50m from EGL either by sand replacement method or by water replacement method

Determination of field moisture as per the IS 2720: Part 18:1992 (Reaffirmed Year: 2021) at nearby borehole locations

Cores are to be sent to the laboratory fordetermining density and specific gravity of rock (IS 13030: 1991, RA 2021), uniaxial compressive strength (UCS) of rock samples of NX size (IS 9143:1979, RA 2021), determination of shear strength of rock materials in triaxial compression as per IS 13047: 1991 (Reaffirmed Year: 2021)

To submit a preliminary site report in three copies along with each bore-log profile, SPT profile results once the borehole SPT tests have been concluded at the site by clearly demarcating (with co-ordinates) the locations of boreholes at site on a contour map or site plan.

Preparation of final report and submission in three hard copies along with soft copy in form of “docx” and “pdf” file format by applying geological and geotechnical engineering analysis by evaluating field findings and laboratory results including site investigation photographs, laboratory test photographs, along with tables and graphs of field and lab test results, conclusions and recommendations.

SOIL TEST AND FOUNDATION DESIGN

GEOTEST ENGINEERS PVT. LTD.

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