Geo-technical Study of Vulnerable Road Slopes on Sanfe Bagar-Martadi Road Section (Ch. 39+720 to Ch. 41+000)

Project Description

Sanfe-Martadi Road Section under Road Division Sanfebagar Achham is a main Highway that connect Sanfebagar of Achhham district to the headquarter of Bajura District. The road section at 39+720 to 41+000 is severely damaged that has hindered the smooth vehicular movements. The division has tried to clear the slide with the use of heavy equipment for the temporary clearance of the slide. The division also has conducted rapid geotechnical study that suggests for the detail geotechnical investigations as the problem is significant enough and requires a permanent solutions of mitigation structures and designs through the geotechnical studies

The main objectives of this study are:
• To identify the causes of Road side slope failure and roadway settlement.
• To provide detail design of mitigation measures including cost estimate.
• To suggest any further studies required to have sustained vehicular operations
• To identify any alternative alignment or solution to existing road corridor

Assignment Description

Acquired and review documents, reports and maps relevant to Sanfe-Martadi project, site geology and landslide hazards/risks; • Collected and reviewed technical manuals and guidelines relevant to detailed slope geotechnical investigation, stability analysis and mitigation design; • Collaborated with Division Road Office Sanfebagar, GESU/DOR and other concerned offices for information and data collection; • Conducted visual reconnaissance of the project alignment to ascertain general geological information and delineate possible exploration locations; • Developed procedures/methods of field investigation and lab testing as well as health and safety standards for field operations; • Mobilized field crews, drilling equipment, testing equipment, survey instruments along with all allied tools at the site; • Carried out geological mapping along the project road corridor to gather information on the soil exposures, weathering situation and major unstable slope cum landslide areas of the project road section; • Carried out slope stability analysis and landslide hazard mapping • Inspect slopes to inventories existing landslides and instability features with detail characterization of slope materials and drainage conditions; • Performed detailed topographic survey of vulnerable slopes area using reliable equipment/technology including drone (UAVs) survey and prepare topographic maps in suitable scale; • Explored slope sub-surface materials through drilling/coring of boreholes (320 m depth), excavation of test pits and profile logging at vulnerable sites up to specified minimum depths or refusal depths; • Label, store and transport cores/samples retrieved from specified depths or intervals; • Undertook ERT surveys 3000 m as required to substantiate bore hole readings; • Executed field tests (SPT) and laboratory tests (index and engineering properties) in accordance with IS Codes, ASTM standards etc.; • Identified suitable construction materials’ sources, quality and quantities to be taken from different source; • Conducted hydrological and meteorological studies to assess the drainage area, flood flows, bank scouring and ground water/ seepage conditions; • Assessed environmental situation to recognize the potential significant impacts and address environmental safeguards in mitigation cost; • Produced instability inventory/susceptibility maps, drainage maps, geological maps and other required engineering maps of the studied area; • Studied the geological, engineering geological, geotechnical, hydrological, topographical and other causative factors of slope instabilities/failures through analysis of field and lab test data; • Delineated the major risk areas and valuate slope stability or safety factor using limit equilibrium or finite element approaches; • Estimated technical and financial requirements for the mitigation or avoidance of high risk slopes and furnish detailed designs/drawings for the most preferable and cost-effective stabilization/protection measures; • Prepared technical specifications, bill of quantities, rate analysis and cost estimates for the proposed mitigation structures; • Developed Inception Report, Draft Report and Final Report with required technical detailing, ready for approval by Client.