Repair and rehabilitation to arrest water leakages

Repair and rehabilitation to arrest water leakages and restoration of Army Bunker –Siliguri using KCPL range of construction chemicals ( Sector- Defence)

Parameters -1) Length of the tunnel is 30.7 m

  • Width -3.85 m
  • Crown-5.6 m
  • Flooring- RCC
  • Sides-12 mm thickness MS sheet

Problems Encountered
  • Perennial Seepage of water from multiple points which increases in rainy seasons and winters.
  • Corrosion of Iron Sheets
  • Freezing of seepage water, which makes movement extremely difficult and slippery during winters

Physical observation

Since the nature of work is confidential and pertaining to Indian army, we base our study on physical observations as shared by the officer-in –charge.

Data Available

As per physical observations carried out, following data/information is collated. An existing tunnel for the purpose of restoration and stoppage of water leakages has been minutely studied/inspected for following challenges:

  • Leakage inside the tunnel
  • Corrosion of MS Plate
  • Freeze thaw effect of seeping water
Tunnel Description with available details
  • Type of Tunnel Horse Shoe Type with combination of heading/drenching/crown
  • Diameter of the Tunnel
  • Length of the tunnel-30.7 M
  • Lining- RCC of M-20 grade concrete
  • Internal Lining- MS Plate 12 mm thick
  • Waterproofing at the time of construction- Polyethylene Sheet
Analysis of Challenge occurred

As the structure with above said detail is having leakage/seepage/dampness because of following reasons as observed

The leakage within the structure is continuous, less in summer season and highest in rainy season which is indicative of following

  • Catchment area of the terrain has some water body/reservoir/fissures etc which with natural course gets into the structure through cracks/fissures/cold joints/lift joints/pinholes/honeycombs etc and splashes trough the tunnel through the plates field welded/shop welded joints or any other cracks in the plates.
  • Waterproofing at the time of construction has failed to arrest to prevalent condition and due to available geological /Hydro behaviour
  • RCC, as lining has shrinkage cracks/hairline cracks. Also the joints in RCC- Construction/Cold/Lift/expansion have been fissured resulting in seepage of water.
Problems Encountered
  • Perennial Seepage of water from multiple points which increases in rainy seasons and winters.
  • Corrosion of Iron Sheets
  • Freezing of seepage water, which makes movement extremely difficult and slippery during winters
Activity flow chart to carry out final assignment

Surface Preparation-The area under leakage treatment has to be well repaired surface by mechanical or manual means (Sand Blasting/scarifying) to remove all loose lattinces, dirt,dust,corrosion,rust,formation of Ferrous oxides extra complete as per manufacturers specifications or instruction of Engineer In charge

Fixing of PVC nozzle complete after drilling at field welded/shock welded joints in the MS Plate and fixing nozzle with epoxy mortar/high strength repair mortar as per as per manufacturers specifications or instruction of Engineer Incharge

Injection of polymer cement slurry by electrically driven pump/manual operated pump with defined pressure and maintaining consistent slurry of Polymer(KUNACRETE) and Cement (OPC 43 Grade),admixed with Non shrink grouting polymeric cement(KUNABEX-100) as per manufacturers specifications or instruction of Engineer Incharge,allowing injected material to get cured for optimum technical properties.

Injection of Micro Fine Cement (KUNA MFC) with required water/powder ratio by electrically or manually operated injection pumps admixed with KUNA –ANTI Freeze admixture in defined proportions as per manufacturer’s specifications or instruction of Engineer Incharge, allowing it to get cured for optimum technical properties

Removal of nozzle for redrilling and fixing of Non Returned valve (NRV) packers of required size and fixing it in position as per manufacturers specifications or instruction of Engineer Incharge

njection of Flexible single component Polyurethane Foam (KUNA PUR Inject 1C Flex) and semi rigid Single component polyurethane foam (KUNA Pur Inject 1C Hydrofoam) by electrically driven pump with defined pressure complete as per manufacturers specifications or instruction of Engineer Incharge.

Removal of Packers

Application of Polyurea Primer over the prepared, dried and injected surface (KUNA UREA Prime) as per manufacturers’ specifications or instruction of Engineer Incharge

Application of Pure spray applied Pure, flexible Polyurea over the cured primer in 2-3 mm thickness as a seamless, flexible water proofing membrane over the steel surface with hot spray plural pump (GRACKO reactor or equivalent only) as per manufacturers specifications or instruction of Engineer Incharge.

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