Euradwaste '08 - EU Bookshop - Europa
Euradwaste '08 - EU Bookshop - Europa Euradwaste '08 - EU Bookshop - Europa
proof of healing in salt rocks. It has to be mentioned that further experiments are necessary to establish the dependency between the mechanical and hydraulic properties of the interfaces between the salt blocks among self and between the blocks and the host rock (rock salt). Figure 3. Shear strength characteristics of lab-dry and moistened brick-brick and brick-rock salt contacts. Healing effects, as indicated by development of cohesion, are promoted by the presence of moisture and increase systematically with stationary ageing over 16, 70 and 94 hours at fixed normal stress (multiple step tests at constant normal stress). – modified after [3]. 3.2 Review of appropriate material laws for modelling granular salt compaction Four published constitutive models (ITASCA, HEIN, ZANG and SPIERS, for details see [1]) describing crushed salt behaviour have been evaluated and adapted to recalculate the measured longterm hydrostatic creep behaviour to remaining porosities in the order of some few percent, i.e. in the order of natural salt. Actually the ZHANG model [5] seems to be the most suitable constitutive law to describe the compaction behaviour of the pre-compacted crushed-salt bricks (compare modeling curves for wet salt in Fig. 1). However an implementation in commercial available codes is necessary allowing prognosis calculations for real underground situations. Nevertheless, the potential of the SPIERS mechanism based pressure solution-model (e.g. [6]) for future modeling is obvious but requires more experimental work. The new MINKLEY-shear model for contact interfaces, which implies the displacement-dependent and the velocity-dependent strength softening is a suitable constitutive law to describe the contact between pre-compacted crushed salt bricks and to the host rock. This shear model is already implemented in a commercial code allowing prognosis calculation for real underground situations. The remaining task is to study and to describe the coupled HM-behaviour of such contact interfaces 474
4. Conclusions Our investigations on artificial salt bricks cover a wide field of relevant rock-mechanical and hydraulical properties of salt bricks, which demonstrate their favourable properties for usage as precompacted elements in sealing or back-filling systems. In this context it has to be mentioned that already practical experiences at relevant in-situ scales are available from the conception of the “Asse-Damm”- project [2] and the technical realisation of the dam - project “Sondershausen” [1]. However, despite the obvious improvements in knowledge and experimental data base it came out during the work that some principal challenges in relation to the salt backfill materials still remain, i.e. (1) Understanding of physical processes which control the efficiency of granular salt compaction especially with respect to humidity effects. (2) Development of generally agreed constitutive models for compaction in granular salt that can be reliably extrapolated to in-situ conditions. 5. Acknowledgements The studies presented have been funded as part of the NF-PRO jointly by the European Commission under the 6 th Euratom Research and Training Framework Programme on Nuclear Energy (2002-2006), contract FI6W-CT2003-02389, and the German Federal Ministry of Research and Education under contract 02 E 9904. References [1] Salzer, K., Popp, T., Böhnel, H., Naumann, D. & Mühlbauer, J., 2007. Investigation of the Mechanical Behaviour of Precompacted Crushed Salt in Contact to the Host Rock. Final Activity Report. 3.5.7. NF-PRO Deliverable 3.5.7: (2007-12-15). [2] Stockmann, N. (ed.) 1994. Dammbau im Salzgebirge, Abschlussbericht Projektphase II, Berichtszeitraum vom 01.07.1989 - 31.12.1992, GSF-Bericht 18/94. [3] Salzer, K., T. Popp & H. Böhnel, (2007): Mechanical and permeability properties of highly precompacted granular salt bricks. In K.-H. Lux, W. Minkley, M. Wallner, & H.R. Hardy, Jr. (eds.), Basic and Applied Salt Mechanics; Proc. of the Sixth Conf. on the Mech. Behaviour of Salt. Hannover 2007. Lisse: Francis & Taylor (Balkema). 239 – 248. [4] Davies, P.B., 1991. Evaluation of the role of threshold pressure in controlling flow of wastegenerated gas into bedded salt at the Waste Isolation Pilot Plant (WIPP). Sandia Rep. SAND 90-3246. [5] Zhang, C. L., Schmidt, M. W., Staupendahl, G., Heemann, U. (1993): Entwicklung eines Stoffansatzes zur Beschreibung des Kompaktionsverhaltens von Salzgrus. Bericht Nr. 93-73 aus dem Institut für Statik der Technischen Universität Braunschweig. [6] Spiers, C. J., Peach, C. J., Brzesowsky, R. H., Schutjens, P. M. T. M., Liezenberg, J. L., Zwart, H.J. (1989): Long-term rheological and transport properties of dry and wet salt rocks, Nuclear Science and Technology, EUR 11848 EN, Office for Official Publications of the European Communities, Luxembourg. 1989. 475
- Page 440 and 441: focuses on the study of the combine
- Page 442 and 443: emitting radioactive waste to study
- Page 444 and 445: 428
- Page 446 and 447: 2.1 Laboratory experiment The dispo
- Page 448 and 449: 3. Results 3.1 Laboratory experimen
- Page 450 and 451: Barrier. Clays in Natural & Enginee
- Page 452 and 453: 2. Experimental data 2.1 Laboratory
- Page 454 and 455: sented in the accompanying poster,
- Page 456 and 457: 440
- Page 458 and 459: situ stress to model the gallery ex
- Page 460 and 461: tive crack network, oriented along
- Page 462 and 463: 446
- Page 464 and 465: ous reasons, SCK•CEN chose to foc
- Page 466 and 467: lery, are already monitoring temper
- Page 468 and 469: [1] Bernier F., Li X.L., Weetjens E
- Page 470 and 471: Concrete The cement used is an Ordi
- Page 472 and 473: Brucite Ettringite 10 �m 8 �m F
- Page 474 and 475: 458
- Page 476 and 477: 2. Methodology In the case of cylin
- Page 478 and 479: cell dismantled after 6 months, roo
- Page 480 and 481: [3] G.E. Gdowski, Humid Air Corrosi
- Page 482 and 483: crucial to predict the hydration ra
- Page 484 and 485: load is higher, since the load appl
- Page 486 and 487: [4] Gens, A. & Alonso, E. 1992. A f
- Page 488 and 489: 2. Experimental Methodology A salt
- Page 492 and 493: 476
- Page 494 and 495: obtained experimental results [1].
- Page 496 and 497: dependent shear strength softening
- Page 498 and 499: 482
- Page 500 and 501: elease falls typically between 1 an
- Page 502 and 503: Figure 3: Left: Spent fuel surface
- Page 504 and 505: 488
- Page 506 and 507: 1. Data compilation and evaluation
- Page 508 and 509: Volumetric deformation [%] 20 18 16
- Page 510 and 511: An overview of the test procedure w
- Page 512 and 513: 496
- Page 514 and 515: The works performed within RTDC-1 p
- Page 516 and 517: Integrated Project “Fundamental P
- Page 518 and 519: 502
- Page 520 and 521: The Ruprechtov natural analogue sit
- Page 522 and 523: esults and integrated to develop a
- Page 524 and 525: 508
- Page 526 and 527: 510
- Page 528 and 529: from 12.5 to 13.5, have high ionic
- Page 530 and 531: elative intensity (cps) 8000 6000 4
- Page 532 and 533: 516
- Page 534 and 535: 518
- Page 536 and 537: 2. SAPIERR I and II In Europe, the
- Page 538 and 539: after extensive interactions have t
4. Conclusions<br />
Our investigations on artificial salt bricks cover a wide field of relevant rock-mechanical and hydraulical<br />
properties of salt bricks, which demonstrate their favourable properties for usage as precompacted<br />
elements in sealing or back-filling systems. In this context it has to be mentioned that<br />
already practical experiences at relevant in-situ scales are available from the conception of the<br />
“Asse-Damm”- project [2] and the technical realisation of the dam - project “Sondershausen” [1].<br />
However, despite the obvious improvements in knowledge and experimental data base it came out<br />
during the work that some principal challenges in relation to the salt backfill materials still remain,<br />
i.e.<br />
(1) Understanding of physical processes which control the efficiency of granular salt compaction<br />
especially with respect to humidity effects.<br />
(2) Development of generally agreed constitutive models for compaction in granular salt that<br />
can be reliably extrapolated to in-situ conditions.<br />
5. Acknowledgements<br />
The studies presented have been funded as part of the NF-PRO jointly by the European Commission<br />
under the 6 th Euratom Research and Training Framework Programme on Nuclear Energy<br />
(2002-2006), contract FI6W-CT2003-02389, and the German Federal Ministry of Research and<br />
Education under contract 02 E 9904.<br />
References<br />
[1] Salzer, K., Popp, T., Böhnel, H., Naumann, D. & Mühlbauer, J., 2007. Investigation of the<br />
Mechanical Behaviour of Precompacted Crushed Salt in Contact to the Host Rock. Final Activity<br />
Report. 3.5.7. NF-PRO Deliverable 3.5.7: (2007-12-15).<br />
[2] Stockmann, N. (ed.) 1994. Dammbau im Salzgebirge, Abschlussbericht Projektphase II, Berichtszeitraum<br />
vom 01.07.1989 - 31.12.1992, GSF-Bericht 18/94.<br />
[3] Salzer, K., T. Popp & H. Böhnel, (2007): Mechanical and permeability properties of highly<br />
precompacted granular salt bricks. In K.-H. Lux, W. Minkley, M. Wallner, & H.R. Hardy, Jr.<br />
(eds.), Basic and Applied Salt Mechanics; Proc. of the Sixth Conf. on the Mech. Behaviour of<br />
Salt. Hannover 2007. Lisse: Francis & Taylor (Balkema). 239 – 248.<br />
[4] Davies, P.B., 1991. Evaluation of the role of threshold pressure in controlling flow of wastegenerated<br />
gas into bedded salt at the Waste Isolation Pilot Plant (WIPP). Sandia Rep. SAND<br />
90-3246.<br />
[5] Zhang, C. L., Schmidt, M. W., Staupendahl, G., Heemann, U. (1993): Entwicklung eines<br />
Stoffansatzes zur Beschreibung des Kompaktionsverhaltens von Salzgrus. Bericht Nr. 93-73<br />
aus dem Institut für Statik der Technischen Universität Braunschweig.<br />
[6] Spiers, C. J., Peach, C. J., Brzesowsky, R. H., Schutjens, P. M. T. M., Liezenberg, J. L.,<br />
Zwart, H.J. (1989): Long-term rheological and transport properties of dry and wet salt rocks,<br />
Nuclear Science and Technology, <strong>EU</strong>R 11848 EN, Office for Official Publications of the European<br />
Communities, Luxembourg. 1989.<br />
475
Change language