Nemi Engineering Services - Engineering Consultants & Contractor for building of Bridges, Road Over Bridges, River under bridges using Box Pushing, Pipe Jacking, Casing Pipe, Trenchless Technology, Pipe Pushing, Push Through,  Box Pushing, Rub, Under Pass, Subway, Culvert By Pushing, Jack Through in Baroda, Gujarat, India
Home | Organisation | Methodolgy | Projects | Inquiry | Contact Us
  “ Special Category Bridge I”
   
  “ Registration as Approved Contractor in AA Class with Government of Gujarat”
   
   
   
  Nemi Engineering Services - Engineering Consultants & Contractor for building of Bridges, Road Over Bridges, River under bridges using Box Pushing, Pipe Jacking, Casing Pipe, Trenchless Technology, Pipe Pushing, Push Through,  Box Pushing, Rub, Under Pass, Subway, Culvert By Pushing, Jack Through in Baroda, Gujarat, India
   
  Nemi Engineering Services - Engineering Consultants & Contractor for building of Bridges, Road Over Bridges, River under bridges using Box Pushing, Pipe Jacking, Casing Pipe, Trenchless Technology, Pipe Pushing, Push Through,  Box Pushing, Rub, Under Pass, Subway, Culvert By Pushing, Jack Through in Baroda, Gujarat, India
   
   
 
   
Methodolgy

Introduction of Box Pushing Technique in Brief :

Present day Intensity of Traffic, both Rail & Road due to the fast development of Industries and other Infrastructures, is very heavy and so it cannot the disturbed, for construction of under bridges or Canal Crossings, drainage etc by conventional i.e. open cut system. So to construct such structures, Box Pushing Technique is developed where in R.C.C. Boxes in segments are cast out side and pushed through the heavy embankments of Rail or Road by Jacking. The required thrust is generated through thrust bed, as well as line & level of precast boxes are also controlled.
Certain items concerned with the method are explained below.

Thrust bed :
The Thrustbed and Thrust Beam and keys are designed in R.C.C. to resist the required Thrust extorted by Jacking force and transfer it to soil at bottom and sides. In cohesive soils even shallow piles are required to transfer the load. Provision for Jacking supports is made by providing suitable Pockets in the bed to accommodate pin supports. On completion of Jacking the thrust bed is utilised as floor bed, and so it is left in place.    
Precast R.C.C. Box

The Precast Box is cast in segments of convenient lengths of Total pushing length. The Box section is designed as per IRS / IRC codes of practice for loading. Concrete grade normally kept as M-35.  

Front Cutting  Shield  &  Rear  Jacking  Shield

The  First  Segment  of  the  precast  box  is  provided  with  a  specially  designed  structure named  as  cutting shield  which  forms  the  front  working  face  with  a cutting  edge  fabricated from  16 to 20 mm thick M.S. Plates  and  housed  on  RCC  Box  section  with  suitable  anchor  bolts. Necessary  strengthening  is provided by stiffeners and  face  plates  of  Box  in  front  on  completion of  jacking the  outer  shell of  the  shield  is  cut  and removed

The  Rear  Jacking  shield  is  provided  by anchoring  steel plate  on  the  face  of  Bottom  slab  of  RCC  Box  suitably  designed  to  distribute  the  jacking  load  uniformly  on  concrete  area.

Intermediate  Jacking  Station

As  total  length  of  Box  is  cast  in  Segments,  each  segment  is  pushed turn by  turn with  necessary  jacking  force  and  so  for  this  necessary  intermediate  jacking  stations  are  provided,  with  jacking  pockets  in  bed  &  walls.

Pushing  Operation  of  the  Box

The  purpose of  pushing of Box is to form a horizontal opening  below ground  or  through embankments, can say a  tunnel, by providing precast box units underground or  an embankment, without disturbing the overhead amenities, like traffic &  structures.

To reduce the frictional resistance, a thin film of Grease and thick gauge plastic sheet is provided between the top of the thrustbed & Bottom of the Box. This is done before casting of the Bottom slab of the box. A Glossy Epoxy layer is also provided to reduce friction on the top and prevent the disturbance of the mass over box to least  during  progress of  pushing 

Where  mass of  embankment is  less or the soil is of poor quality, drag sheet  system is  also considered for least  resistance of  friction and disturbance of mass above box.

Auxiliary beds are also provided for casting of the other segments with thin film of grease and plastic and segments are then brought in alignment of pushing as and when required as pushing progresses.

With  the  progress of jacking,  the  front  unit  with  shield  penetrates  into  the  embankment  and there after  excavation within the shield is done  either  manually  or  mechanically   and  the  excavated  stuff  is  transported  outside the  working  area.

After the first segment advances to the end of the thrustbed, the second segment is brought in alignment of the front Box & intermediate jacking space is lift between the two. The progress of pushing is kept continuous and the system of side shifting of remaining box segments from Auxiliary bed and bring in pushing alignment is adopted till total length is pushed.

Hydraulic Equipment

The entire Box Pushing system is matter of proper selection of Hydraulic equipments, as tremendous driving force is required for pushing of medium to large size of Boxes. So for this, Number of Jack units are provided in series for distribution of pushing load evenly on the face of the concrete, and all Jacks are operated simultaneously with a common power pack, which supplies uniform flow of pressure through network of Hydraulic pipes  of required pressure capacity, commencing from front unit to rear unit. Jacking force is applied in sequence. This way pushing cycles are repeated till total pushing is completed.

Conclusion

The entire system is purely technical, dependent on Hydraulic system, & safest method of crossing underground / Embankment, without disturbing overhead traffic / structures for R.U.B., Canal siphon and other drainage crossings.

Home | Organisation | Methodolgy | Projects | Inquiry | Contact Us
Powered By : Barodaweb- The E-Catalogue Designer