The dynamic pipe propulsion with the ramming method uses pneumatic pipe ramming machines. With these, you can lay open steel pipes beneath railway tracks, highways and rivers, either as protection or product pipes, with diameters up to 4000 mm for lengths of up to 80 m in the soil classifications 1 - 5 (partially even in classification 6 - easily removable rock) without using pressing abutments.


Pipe ramming method

The pneumatically driven ramming machine has a cylindrical shape with a front, or respectively a rear cone for connecting the add-on cones, cotter segments and/or soil-removal cones/adaptors which create a tight-fitting connection between pipe and machine. When using the soil removal cones/adaptors, part of the soil core, which is carried along, can come out through two openings and exit. The application of cotter segments avoids flaring of the pipe and enables butt welding of the single pipe lengths. Bulging welding seams of spiral welded pipes have to be smoothed to level with the pipe material in the area of the segment fitting depth in order to prevent point pressure loads.

The ramming machine is driven by a conventional compressor. After being welded together, the single pipe lengths are pushed forward gradually. Due to the robust one-piece construction, TT Group’s largest ramming machine can achieve an impact energy of 40.000 Nm (at full capacity) which is transferred optimally over the complete pipe string to the pipe’s front cutting edge. The average ramming speed is 10 m/hour.


Job-Site: Double Railway crossing near Newcastle, UK

After conclusion of the ramming work, the pipe spoil is removed completely using water pressure in combination with compressed air or water pressure alone - up to ND 500 soil removal is only allowed with compressed air after having taken the appropriate safety measures. With larger pipe diameters the soil can be removed manually with the help of certain auxiliaries. (See operating instructions!)

According to the latest investigations by Prof. Dr. Stein, the wall thickness calculation following ATV-A 161 and GW 312 is basically possible; but examinations have proved that the external soil pressure, acting on dynamically driven steel pipes, due to soil weight and dynamic traffic loads, is distinctively lower than the corresponding comparative values for pipes installed with a trenchless method according to ATV-A 161. Following this, the wall thickness of the pipes could be reduced correspondingly.

The ramming machines have proved successful in practice - the Ruhrgas AG has given the rating "recommended". From a constructional point of view, the German Bahn AG prefers cased-in methods, e. g. the ramming technique, to uncased boring methods. The ramming technique is described in the German guideline ATV-A 125 and in the GW 304 Pipe Laying, as well as in other German standards.

With the Tracto-Technik rammers, you have a multiple choice of application possibilities.
1. Horizontal, as well as vertical pipe laying is possible, example when laying foundations.
2. A special adapter allows you to use the rammer for driving sheet piles.
3. As a third possibility, it can be applied for the renewal of pipe lines (dynamic pipe bursting).
4. Producing pipe shields for tunnel tubes

All ramming models have thoroughly been examined by the TBG (German Civil Engineering Co-operative).

Advantages of the method:
- surfaces worth conserving are neither broken up nor (road surface, front gardens etc.), restoration and are not required
- which gives you an economical advantage
- low social costs, because detours, half-sided barriers, facilities etc. are avoided
- acknowledged procedure
- short set-up times - short pipe laying times
- the dynamic propulsion of the impact can shatter and easily
- surmounts stronger starting resistance after standstill precision is improved, because the dynamic impact shatters varying formations within the diameter range, obstacles need not be displaced in one or pushed along
- no pressing abutment, no conveyor spiral, which could jammed
- no flooding when working on river crossings
- minimal covering, no elaborate pits
- simple operation technique
- adaptation to all pipe diameters with special ram cones
- wide spectrum of application