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Micropiles
Micropiles

RR® and RD® micropiles

Micropiles offer an effective and convenient way to implement the piling

The easy-to-use and cost-efficient splicing method allows quick installation of RR® and RD® micropiles with minimal material waste.

Micropiles consist of a longitudinally welded steel pipe, mechanical splices, a tip and a bearing plate.

The selection of a suitable micropile type should be based primarily on soil conditions, but superstructures and ambient structures also play a major role..

 

Applications:

  • Office and business buildings
  • Industrial buildings
  • Residential buildings
  • Public buildings
  • Road and railway structures and bridges

Micropile installation

RR® micropiles can be installed using light basic equipment (<20 to 25 t) up to a size of about RR170. They can be installed by impact driving or jacking. A heavy hammer may be advantageous when driving RR® micropiles into dense soil, but it also increases the risk of bending. Pile cushions are usually not needed. If a micropile cushion is not used, a dolly made of a thick steel plate is used between the hammer and the pile. The head of the micropile is adjusted inside the lower part of the helmet to ensure that the impact is transmitted centrically.

RD® micropile installation can be done in all soil conditions. They may be drilled through all natural soil layers all the way into bedrock, with small deviations in position and inclination. In very exacting conditions, such as those involving thick fill layers containing large boulders, the smallest diameter micropiles may pose a slightly higher risk of bending in comparison to large diameter micropiles.

For more information regarding RR® and RD® micropile installation, see SSAB’s RR® and RD® piles design and installation manual.

Micropile design

Micropile design requires that micropile foundations are always designed together withthe structures to be supported on it, which allows selecting the most suitable shape, dimensionsand stiffness for the entire structure.

The RR® micropiles are delivered either as pipes or as ready-made elements with an external sleeve splice at one end of the element. They are designed to offer quick and cost-effective splicing, minor displacement of soil, minor vibration disturbance and high installation strength.

The RD® micropiles are delivered as pipes when splicing is done by welding. Another option is threaded RDT splices in which case the piles are delivered as ready-made elements with both ends threaded and with external threaded sleeves.

An RDT micropile comprises:

  • A bearing plate installed on the upper end of the micropile
  • An external threaded sleeve
  • Extension pipe (both ends are threaded)
  • Starter micropile (one end is threaded)
  • A casing shoe and reamer bit (in concentric drilling) at the lower end of the micropile

For the standard lengths of the micropile elements, the sectional properties and the steel grades, see SSAB’s RR® and RD® piles design and installation manual.

RRPileCalc is a design program for SSAB's steel micropiles. Eurocodes as well as National codes and instructions are applied in the end-bearing micropile design. See the Design Tools section below for more information.

RR® micropile

Driven RR® micropile with effective splicing technology

RR® micropiles offer quick and cost-effective splicing, minor displacement of soil, minor vibration disturbance and high installation strength. They are installed by impact driving or jacking.
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RR-pile

 

RR® micropile

Driven RR® micropile with effective splicing technology

RR® micropiles offer quick and cost-effective splicing, minor displacement of soil, minor vibration disturbance and high installation strength. They are installed by impact driving or jacking.

Structure:

Micropile pipes and elements

The RR® micropiles are delivered either as micropile pipes or as ready-made micropile elements with an external sleeve splice at one end of the element.

Splicing of RR® micropiles

The RR® micropiles utilize friction-based splices that meet the requirements set for rigid splices in the EAD 200005-00-0103, a base document for acquiring CE marking for steel piles, and in the Finnish national annex to EN 1993-5.

  • In RR75 - RR245 micropiles, the splice is an external double conical sleeve splice.
  • Keeping the external splice in place during driving is ensured by welding, which is done at the factory as the splice is made. No welding of the splice is needed on site.
  • RR270 - RR320 micropiles are spliced by welding.


If splicing is done by welding, SSAB’s RR® and RD® micropile design and installation manual provides recommendations concerning the creation of welded splices.

Bearing plate

Usually a bearing plate is installed at the upper end of RR® micropiles to transfer loads from the superstructure to the micropile. The bearing plate is centred on the micropile shaft by an internal sleeve, which serves to keep the bearing plate in place.

Micropile shoes

The mechanically attached micropile shoes of RR® micropiles, bottom plates and rock shoes, meet the requirements of PO-2016. The rock shoe dowel is made of hardened special steel, which ensures good penetration into bedrock.
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RD® micropile

Drilled micropiles for drilling in difficult ground conditions

RD® micropiles may be drilled through all natural soil layers all the way into bedrock, with small deviations in position and inclination.
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RD-pile

RD® micropiles

Drilled micropiles for drilling in difficult ground conditions

The micropiles may be drilled through all natural soil layers all the way into bedrock, with small deviations in position and inclination.

Structure:

RD® micropiles are delivered either as pipes or as ready-made elements with threaded heads.

An RD® micropile comprises:

  • A bearing plate installed on the upper end of the micropile
  • An external threaded sleeve
  • Extension pipe (both ends are threaded)
  • Starter micropile (one end is threaded)
  • A casing shoe and reamer bit (in concentric drilling) at the lower end of the micropile

 

RDT – RD® micropile with threaded sleeve splice

RD® micropiles are spliced either by an external threaded sleeve or by welding. The advantages of a threaded sleeve are:

  • Reduced installation time. Less turns needed during splicing.
  • Identical sleeve for all available steel grade and wall thickness combinations in each micropile diameter where threaded splicing is available. Always right sleeve selected and less waste thanks to the possibility to use same sleeve in all job sites.
  • High-quality end result also in difficult installation conditions.

The design is CE marked and meets all technical requirements for micropile splices. The tensile strength of a splice is guaranteed to be 50% of the compressive strength of the micropile.

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Shaft-grouted RR® micropile

Shaft-grouted RR® micropile and fitted equipment

These micropiles are mainly shaft-bearing piles where the geotechnical bearing resistance of the shaft is improved through continuous shaft grouting. These are suitable for frictional soils where the high shaft resistance of grouted micropiles allows using essentially shorter piles.
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Shaft-grouted RR® micropile

Shaft-grouted RR® micropile and fitted equipment

These micropiles are mainly shaft-bearing micropiles where the geotechnical bearing resistance of the shaft is improved through continuous shaft grouting. These are suitable for frictional soils where the high shaft resistance of grouted micropiles allows using essentially shorter piles.

Structure:

RR® micropiles are delivered either as pipes or as ready-made elements with an external sleeve splice at one end of the element.

Collar with grouting holes

The installation of a shaft-grouted RR® micropile involves feeding grout into the micropile from the top which then discharges into the space and soil surrounding the micropile through the grouting holes at the lower end. A collar is attached to the lower end of a driven micropile to make sufficient room for the grout around the micropile. The injection holes are in the lower end of the pile.

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Build stronger with high performance RRs and RDs steel micropiles

Our high-strength RR® and RD® micropiles, in combination with efficient designing, easy and quick installation, lower environmental impact than traditional piling create a solution that is now stronger than ever.

By using the higher steel grade S550J2H, the micropiles load-bearing capacity can be added by up to 20% over that of steel grade S460MH. The increased load-bearing capacity of the pile can be maximized by using smaller micropiles or decreasing the number of micropiles. For the customer, this means a significant improvement in the overall economy of the project.
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RRs-piles

 

High performance RRs® and RDs® micropiles

Higher load-bearing capacity and lower costs

RRs micropile selection includes most of the common RR pile sizes

The excellent properties of the RR® micropiles, such as splicing easily and quickly with an external friction splice as well as other micropile accessories, are utilized also in RRs micropiles manufactured of high-strength steel.

Advantages of the high-strength steel S550J2H in SSAB's RRs micropiles:
By using the higher steel grade S550J2H, micropile’s load-bearing capacity can be added by up to 20 % over that of traditional RR® micropiles. The increased load-bearing capacity of the pile enables decreasing the number of micropiles.

Alternatively, an RRs micropile made of high strength steel can replace an RR® micropile with bigger size. Good example of this is RRs125/6.3 micropile size, which can easily replace micropile size RR115/8.

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Design tools

Software for fast and easy design

RRPileCalc is a design program for SSAB's steel piles. Eurocodes as well as National codes and instructions are applied in the end-bearing pile design.

PileWallCalc design tool enables easy calculation of cross section properties and bending resistances of the pile walls. The program calculates the bending resistances and normal force resistances of RD® pile wall, Combi wall and Zig-Zag Combi wall.
Find out more

Environmental responsibility and sustainability

SSAB develops new products and services in order to improve our customers’ performance in sustainability and overall efficiency.

Life cycle assessment data for SSAB’s products are available in the form of Environmental product declarations (EPDs). Manufacturing chain from raw material to finished product is carefully managed.

SSAB has introduced CE marking for infrastructure products. Declarations of Performance (DoP) indicate the technical characteristics of CE-marked products.
Find out more

Customer cases

Read about our customers' success using SSAB's Infrastructure products

Find out more

Availability of micropiles: section lengths and micropile pipe lengths.For project specific dimensions, please contact our sales.

RR® pile

Mill dimensions of RR (S460MH) and RRs (S550J2H) pile sections and pile pipes

Length of pile section (incl. splice)  
 Length of pile pipe (excl. splice) 

12 m
  6 m
 4 m 3 m
 2 m
 1.5 m
 1.2 m
 1.0 m
  6 m
 12 m
 16 m
 RR75 -
 X
 O
 O
 O
 O
 O
 O
   X
 O
 -
 RR90 - X
O
O
O
O
O
O
  X
O
-
 RR115/6.3 O X
O
O
O
O
O
O
  X
O
O
 RR115/8 O
X
O
O
O
O
O
O
  O
X
O
 RR140/8 X
X
O
O O
O
O
O
  O
X
O
 RR140/10 X
X
O
O
O
O
O
O
  O
X
O
 RR170/10 X
X
O
O
O
O
O
O
  O
X
O
 RR170/12.5 X
O
O
O
O
O
O
O
  O
X
O
 RR220/10 X
O
O
O
-
-
-
-
  O
X
O
 RR220/12.5 X
O
O
O
-
-
-
-
  O
X
O
 RR245/10 X O O O - - - -   O X O
RR245/12.5 X O O O - - - -   O X O
                         
RRs115/8 O
X
O
O
O
O
O
O
  O X
O
RRs125/6.3
X
X
O
O
-
-
-
-
  O
X
-
RRs140/8 X
X
O
O
O
O
O
O
  O
X
O
RRs140/10 X
O
O
O
O
O
O
O
  O
X
O
RRs170/10 X
O
O
O
O
O
O
O
  O
X
O
RRs220/10
X
O
O
O
-
-
-
-
  O
X
O
RRs220/12.5 X O O O - - - -   O X O
RRs245/10 X O O O - - - -   O X O
RRs245/12.5 X O O O - - - -   O X O
 X = stock size      O = project-specific size      – = not in production
RD® pile

Mill dimensions of RD (S460MH) and RDs (S550J2H) pile sections and pile pipes


Length of pile section with threaded ends 
  1 m
 1.2 m
 1.5 m
 2 m
 3 m
 4 m
 6 m
 12 m
RDT90 O O O O O O O -
RDT115/6.3 O O O O O O O O
RDT115/8
 O
 O
 O
 O
 X
 O
 O
 O
RDT140/8
 O
 O
 O
 O
 O
 O
 O
 O
RDT140/10
 O
 O
 O
 O
 O
 O
 X
 O
RDT170/10
 O
 O
 O
 O
 O
 O
 X
 O
RDT170/12.5
 O
 O
 O
 O
 O
 O
 X
 O
RDT220/10
 O
 O
 O
 O
 O
 O
 O
 O
RDT220/12.5
 O
 O
 O
 O
 O
 O
 X
 O
RDT270/10 O O O O O O O O
RDT270/12.5 O O O O O O O O
RDT320/10 O O O O O O O O
RDT320/12.5 O O O O O O O O









RDTs115/8
 O
 O
 O
 O
 O
 O
 O
 O
RDTs140/8
 O
 O
 O
 O
 O
 O
 O
 O
RDTs140/10
 O
 O
 O
 O
 O
 O
 O
 O
RDTs170/10
 O
 O
 O
 O
 O
 O
 O
 O
RDTs170/12.5
 O
 O
 O
 O
 O
 O
 X
 O
RDTs220/10
 O
 O
 O
 O
 O
 O
 O
 O
RDTs220/12.5
 O
 O
 O
 O
 O
 O
 X
 O
RDTs270/10 O O O O O O O O
RDTs270/12.5 O O O O O O O O
RDTs320/10 O O O O O O O O
RDTs320/12.5 O O O O O O O O

X = stock size      O = project-specific size      – = not in production

 


  Lenght of pile pipe without threads
  1 m
1.2 m
 1.5 m
 2 m
3 m
4 m
6 m
12 m
12 - 16 m
16 - 34 m
RD90 O O O O O O X - - -
RD115/6.3 O O O O O O X O - -
RD115/8 O O O O O O O X O -
RD140-RD320 O O O O O O O X O O
RDs90 O O O O O O O - - -
RDs100 O O O O O O O - - -
RDs115/6.3 O O O O O O O O - -
RDs115/8 O O O O O O O X O -
RDs125/6.3 O O O O O O O X - -
RDs140-RDs320 O O O O O O O X O -

X = stock size      O = project-specific size      – = not in production

 

 

Downloads

Document type
RR® and RD® piles design and installation manual
2,09 Mb
Steel piles
2,99 Mb
SSAB Design resistance tables for RR® and RD® piles made of S440J2H steel grade
225 Kb
Infra tools for designers
1,52 Mb
RRs® piles optimizing leaflet
530 Kb
Piles recommendations for safe handling on site
587 Kb
RR® piles End-of-driving tables and curves for different pile driving equipment
8,21 Mb
SSAB RR and RD piles Preheating and cooling of splice welds
425 Kb
Revit Family for SSAB piles
665 Kb
English
EPD Norway: Tubular products
2,33 Mb
English
EPD: Steel piles
446 Kb
English
ETA 12/0526 - European Technical Assessment for RR and RD piles
1,32 Mb
English