ROCARC - Rock anchoring for stabilization of infrastructures

ROCARC - Rock anchoring for stabilization of infrastructures with focus on the arching effect and rock-grout bond

ROCARC - Rock anchoring for stabilization of infrastructures

– RCN project number: 303448

About and project description

Illustration rock anchoring

The project lasts for four years, from 1 August 2020 to 31 July 2024. It is financially supported by Research Council of Norway (RCN) as well as the research institutions and industrial partners in the consortium. One doctoral student and one post-doc are involved in the project. The host institution of the project is Department of Geoscience and Petroleum, NTNU.

Project description

High capacity rock anchors are used to stabilise rock slopes, retaining walls and large-scale infrastructures (Fig. 1a and b). Failure of the rock anchors would jeopardise the infrastructures and lead to serious economic and social consequences. Rock anchors are composed of a single or multi strands of cables which have a bonded length that is fixed deeply in the rock mass and a free length that is attached with fixture units on the ground surface. The current rock anchor dimensioning has some uncertainties because of the limited knowledge in the failure of the rock mass and the rock-grout bond strength (Fig. 1c). New knowledge in rock anchoring is required to improve the rock anchor design and to enhance relevant engineering education.

ROCARC aims to develop an updated method for the dimensioning of rock anchors. The investigations include, among others, the load transferring between the anchor and the rock mass, the failure mode of the rock mass, and the bond strength between the grout and the rock. The research will be carried out through laboratory model tests, field trials and numerical modelling. The laboratory tests aim to study how the rock mass responds to the anchor load and how the failure is initiated and propagates in the model materials. A two-dimensional test rig will be constructed for the model tests, where the deformation and load transferring in the model materials will be monitored. The field trials are carried out in rock masses to investigate how the anchor load is transferred to the rock mass and how the conical failure surface is formed in the rock mass. Pullout tests of full-scale rock anchors are also carried out in the field to formulate a realistic method for determining the rock-grout bond strength. Numerical modelling is used both in the laboratory and field tests for parameter studies and for the help of test design. In the end, a numerical modelling methodology will be established for rock anchor design.

illustrasjon rocarc

Illustrasjon rocarc

Fig. 1. Examples of pre-stressed anchors and failure modes of a rock anchor. (a) Anchors supporting a retaining wall, (b) anchors stabilising a dam and (c) schematic of four failure modes of a rock anchor: 1 – failure in the rock, 2 – failure at the grout-rock interface, 3 – failure in the anchor-grout interface, and 4 – rupture of the anchor strand. 


ROCARC annual seminar in 2021

ROCARC Annual Seminar in 2021

 

The annual seminar of the project ROCARC was held on 10 November 2021 in NTNU. The participants were people from the consortium partners and some external experts in the reference group of the project. The following six presentations were delivered in the seminar:

  1. A brief of the project progress, Charlie Li, IGP/NTNU.
  2. Laboratory tests on the failure mode of frictional and low-cohesive materials under of a ground anchor, Hanna Høgset, NTNU/Rambøll.
  3. Laboratory tests and numerical modeling of block models for evaluation of rock mass behaviour when subject to an anchoring load, Karsten Aasbø, NTNU/NCC.
  4. A literature study and field pull tests in Tromsdalen, Bjarte Grindheim and Charlie Li, NTNU.
  5. Rock bond strength site investigation tests, Andris Bērziņš, Peikko Group Corporation Latvia.
  6. Road cut support using partial factor and safety factor methods, Johanne Austad, NTNU; Are Håvard Høien, NPRA.

Laboratory model tests in frictional and low-cohesive materials

Two-dimensional physical model tests were carried out on a mini test rig to study the failure pattern of frictional and low-cohesive materials under a concentrated upward load in the middle of the model which simulated the loading condition of a rock anchor. The anchor block in the model transferred the load to the material through friction at the block-material interface. A conic failure body was uplifted to the end both in the frictional and low-cohesive materials. 

ROCARC pullout soils

Laboratory tests of block models

Two-dimensional block models were tested in the same loading means as the tests of the frictional and low-cohesive materials on the mini test rig to study the load-arching effect in blocky rock masses and also the failure pattern of the blocks under the load of a rock anchor. The full-field strains were measured by DIC technology. The load-arching effect was clearly observed in the block models. The failure pattern is also conic in the block models.

ROCARC pullout block model

Field pull tests of rock anchors

Full-scale field pull tests were carried out in limestone quarry to test the load capacity of the anchors with different anchoring schemes. The tests showed that the anchoring method affected the behaviour of the rock anchor. The results of the field tests are under analysis at present.

ROCARC pullout field tests

Summary Webinar 2020

ROCARC Webinar 2020

Knowledge Exchange in Rock Anchoring

Summary

 

The webinar was successfully organised on 18th November 2020, from 9h00 to 13h40. Number of attendees was 97, mostly from Scandinavian countries. There were also attendees from Colombia and Vietnam.

As planned, a total of 8 presentations were presented. Presenters and titles with link to presentations:

  1. Charlie Li, IGP/ NTNU, Introduction to the project ROCARC - Rock anchoring for stabilization of infrastructures with focus on the arching effect and rock-grout bond
  2. Magnus Sørensen, Multiconsult, 2D-modellering av bergforankrede vindturbinfundamenter
  3. Mahdi Shabanimashcool, NGI, Rock anchored foundations for wind turbines - 3D modelling
  4. Andreas Ongstad, Norconsult, Forankringer i berg - FoU og praksis i Norconsult
  5. Leif Lia, IBM/ NTNU, Rock anchors on Norwegian dams
  6. Peter Lundqvist, Vattenfall, Sweden, A new guideline on post-tensioning tendons for dam-owners in Sweden
  7. Tor Harald Hanssen, Comrod Utility Systems AS, Fundamentering av kraftmaster - historien, utfordringer og tester gjennomført av Comrod
  8. Jessica Ka Yi Chiu, NGI, Anchorage of tower foundations in rock - Classification of rock ground and design rules

During the webinar, lot of issues were presented and discussed. The mentioned issuses were:

  • Considerations during analytical calculation of capacity of the rock anchoring. 
  • Numerical modelling (2D, 3D) of rock anchoring in different rock mass conditions.
  • Measurements in anchoring.
  • In-situ test of anchor.
  • Application of rock anchoring in dams and spillways.
  • Application of rock anchoring in windmill and power transmission lines.
  • Failures of anchoring. 

Lot of knowledge has been exchanged between industry and academic as well as between professionals. 

PDF-file of SUMMARY: ROCARC Webinar 2020


NTNU logo​​​ UiT logo Statens vegvesen logo NBG logo  NGI logo Multiconsult logo Norconsult logo NORSAR logo

 

 


News

News

10. November 2021 - The annual seminar of the project ROCARC was held in NTNU.

6.-29. October 2021- The first field tests were completed. Pullout testing of 14 rock anchors at Verdalskalk. 

18. November 2020 - ROCARC Webinar 2020: Knowledge Exchange in Rock Anchoring.

13. August 2020 - Kick-of meeting: The kick-off meeting of the project was held digital via Teams on 13. August 2020. 

Meeting participants: Charlie Li, NTNU; Bjørn R. Sørensen, UiT; Lisbeth-Ingrid Alnæs, SINTEF; Nghia Quoc Trinh, SINTEF; Kristoffer Lund Vik-Langlie, NTNU; Andreas Wuestefeld, NORSAR; Roger Olsson, NGI; Are Håvard Høien, Statens vegvesen direktorat; Hugo Vanje-Remlo, UiT; Per Heimli, Multiconsult; Hanne Elisabeth Wiig, NBG; Andreas Ongstad, Norconsult; Bjarte Grindheim, NTNU; Leif Lia, NTNU

screenshot from teams kick-off meeting

10. August 2020 - Doctoral student Bjarte Grindheim started his study in the project.

20. February 2020 - Statens vegvesen finaniserer modellforsøk av fjellforankring med stag.

Hanna Høgset, student IGP, Are Håvard Høien, Statens Vegvesen, Karsten Sannes Aasbø, student IGP og Charlie Chunlin Li, professor IGP

 

 

 


Organisation

Organisation

Consortium members

Consortium members:

  • Department of Geoscience and Petroleum (IGP) NTNU
  • Department of Civil and Environmental Engineering (IBM) NTNU
  • University of Tromsø (UiT)
  • Norwegian Public Roads Administration (NPRA)
  • Norwegian Group for Rock Mechanics (NBG)
  • SINTEF Building and Infrastructure
  • Norwegian Geotechnical Institute (NGI)
  • NORSAR
  • Multiconsult AS
  • Norconsult AS

Support member:

FME research center Hydrocen


Rocarc

Rocarc

WP1 Management
Leader: Charlie Li, NTNU

WP2 Laboratory test
Leader: Are Håvard Høien, NPRA
are.hoien@vegvesen.no

WP3 Field tests
Leader: Leif Lia, NTNU

WP4 Num. modelling
Leader: Roger Olsson, NGI
roger.olsson@ngi.no

WP5 Dissemination
Leader: Nghia Trinh, SINTEF
nghia.trinh@sintef.no

 


Files from events

Files from events

 

2021

  • ROCARC annual seminar 2021

2020