FRONT JACKING method is

A method to build underground structures in a trenchless way at the bottom of railways, roads, tunnels
It is a method of installing a pipe loop ball and then, manufacturing Precast structure from the outside, and pulling the structure to a predetermined position using the tip press-fit flooring and PC steel wire.
Since introduced to Korea, this construction method has more than 1,100 construction achievements and technical know-how and has proved its safety and excellence

Features of FRONT JACKING construction method

1) Precast structures are manufactured from the outside, so it is easy to control quality
2) Tip press-fit flooring JACK is used, enabling propulsion without top side displacement
3) Pipe loop ball steel pipe is used to manage ground reinforcement Grouting Parallel construction measurement.
4) Excellent safety, construction is possible regardless of structure size, soil quality.

Classification of FRONT JACKING methods

The pulling methods of the structure include unilateral pulling method and mutual pulling method, and if construction extension is long distance, the structure is divided and towed.
The unilateral pulling method is a method of towing in the ground in one direction using the opposite ground or mounding and existing structures (retaining walls, approach structures, etc.) as the reaction force body.
The mutual pulling method is a method of dividing a structure into a plurality and constructing them on both sides of a crossing point, and towing the structure in the ground using each other as reaction force.

Structure pulling method

A photo of construction by FRONT JACKING method

Construction order of FRONT JACKING Construction Method mutual pulling

1. Installation of piles for temporary facilities
2. Improvement of transverse section ground (if necessary)
3. Pipe loop propulsion reaction force object

4. Installation of departure /arrival base
5. Horizontal boring
6. Installation of guide pilot tunnel
7. Departure stand construction
8. Assembly of casing shoe and construction of structures

9. Traction preparation ball
10. Reaction wall in casing shoe

11. First structure ball traction and casing shoe penetration
12. Pulling and drilling of first structure
13. Removal of some pulling facilities after the installation of the first structure at a predetermined position

14. Second structure ball traction and casing shoe penetration
15. Pulling and drilling of second structure
16. Removal of casing shoe
17. Traction complete
18. Joint waterproofing
19. Joint waterproofing

FRONT JACKING method unilateral traction construction sequence

1. Installation of temporary facilities
2. Improvement of transverse section ground (if necessary)
3. Installation of departure /arrival base
4. Pipe loop propulsion

5. Horizontal boring
6. Installation of guide pilot tunnel
7. Installation of departure stand
8. Installation of reaction structure
9. Assembly of casing shoe and construction of traction structures

10. Traction preparation ball

11. Structure ball traction, casing shoe penetration
12. Pulling and drilling of structure

13. Traction complete
14. Joint waterproofing
15. Removal of casing shoe and manufacture of casing shoe sub-structure
16. Joint waterproofing