Pipe Ramming
 

Introduction:

For the dynamic pipe installation according to the ramming technique pneumatically driven pipe ramming machines are used. These machines enable the economic installation of open steel pipes as casing or product pipes up to 4m diameter over lengths up to 80 m in soils. “Pipe Ramming is comparable to driving vertical piles only in this case the piles are being driven horizontally into the ground. The method is useful for installations under railways and roads, where other trenchless methods could cause surface settlement or heave. The method is pneumatic, i.e. it uses pneumatic percussive blows to drive the pipe into the ground”.

Technical Information:

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.

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.

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.

Advantages of the technique:

  • Less disruption and damage of surfaces worth conserving (road surface, front gardens etc.) and minimal restoration - giving economic advantages.
  • Low social costs because detours, half-sided barriers, traffic signal facilities etc. are avoided.
  • Acknowledged pipe installation technique, adaptation to all pipe diameters with special ram cones & simple operating technique & wide application range.
  • Short setting-up times - short installation times.
  • The dynamic impact when ramming can shatter obstacles and easily overcome difficult starting resistance after standstill periods. The aiming accuracy is improved because the dynamic impact shatters various soil formations within the diameter range and obstacles don't have to be displaced or pushed aside in one piece.
  • No jacking abutment, no auger cutter required, which could get jammed.
  • The soil core remains in the pipe during ramming, i. e. no inrush of water when rivers or high water table areas are under-crossed.

Plant Description:


 
Pipe Ramming Set-up Detail

Coffey Job Experience:

Wicklow Port Access Road Job - As part of the Wicklow Port Access Town Relief Road there was a requirement to provide two 1500mm diameter steel pipe sleeves underneath the Railway lines located at the Murrough which is located Northeast of Wicklow Town. One of these sleeves was to receive watermain, foulsewer, gas main and telemetry ducting in the immediate future. The other sleeve was to remain open until sometime where services may be placed in position in the future. The two sleeves would have to be 20 meters in length. After consultations between Coffey Construction, Wicklow County Council and Iarnród Éireann personnel it was decided that Pipe Ramming would be a viable solution for the installation of the sleeves.

Lucan Palmerstown Water Supply extension. - Two 900mm diameter steel pipe sleeves underneath the railway line. One of these sleeves was to receive watermain, The other sleeve was to remain open until sometime where services may be placed in position in the future. The two sleeves would have to be 19 meters in length.

Ballymore Eustace Water Supply Scheme – As part of the contract the following ramming was carried out.

  • Two 600mm diameter steel pipe sleeves underneath the Nass road. One of these sleeves was to receive watermain. The other sleeve was to remain open until sometime where services may be placed in position in the future. The two sleeves would have to be 25 meters in length.

  • One 1000mm diameter steel pipe sleeves underneath the Nass Road. The sleeve was to receive watermain. The sleeve would have to be 22 meters in length.


Tuam Regional Water Supply Scheme – extension to Athenry - Part of this scheme runs through Athenry calling for a new main to be laid beneath the Dublin – Galway and Galway – Limerick railway lines at a number of designated crossings.  As it was essential to maintain all scheduled services, the trenchless technology method of Steel Pipe Ramming was employed. A single 500mm dia steel pipe was driven and would have a length of about 12m.

Swansea Enterprise Park Drain Crossing - The Swansea Joint Venture’s (a partnership between the City and County of Swansea and the Welsh Development Agency) role is to provide the necessary infrastructure and a significant investment (over £25 million to date) has been made with respect to roads, services and landscaping. Swansea City & County Council (S.C.C.C) is currently undertaking a large scale drainage scheme as part of this investment to service extensive areas of land in the Swansea Vale site. The first part of this scheme was to place a 600 mm diameter concrete storm water pipe beneath a dual carriageway. Due to the 7 metre high embankments at the point of crossing & due to the fact that spine road 6 could not be closed for any considerable period of time, it became increasingly obvious to S.C.C.C that a Trenchless Technology method of pipe laying was needed. The crossing at the Swansea Vale site was to be 52 metres in length and called for the installation of a 900mm diameter steel pipe through which will pass the 600mm PE storm-water pipe.


Egham Railway Line Crossing - Between Staines & Egham Stations. The Proposed Undertrack Crossing was for North Surrey Water – Walton to Egham link rising main. The steel pipe had a diameter of 1066mm and a length of 36 metres overall. The steel sleeve was pipe rammed horizontally under Railtrack property.


Thames River Crossing - Installation of a 863.6mm diameter by 25mm thick wall steel pipe by 65 metres long as a sleeve pipe for a 500mm diameter ductile iron water main beneath the River Thames. A 13.2 long x 4.8m wide star1/work pit was excavated to 10 metres deep and framed. A structural concrete slab cast in the base. - A 610 x 305 steel channel was cast into the concrete base of the launch pit accurately on line and level, to act as a launching cradle, support for the successive lengths of 8 metre long pipes. On the top of each pipe were welded two pipes, one for the GRUNDOCONTROL and the smaller pipe for Bentonite injected under pressure. The GRUNDOCONTROL was periodically inserted to accurately measure for any deviation in level, and the Bentonite was used to "wet/lubricate the stiff/firm silty clay and also reduce the surface friction on the pipe.

Coffey Group, Athenry, Co. Galway, Ireland Tel: +353 91 844356 Fax: +353 91 844519 Email: info@coffeygroup.com