Safely disposal of high-level radioactive waste (HLW) is of great importance for development of nuclear industry. Deep geological disposal has been commonly recognized as a suitable way. In a conceptual multi-barrier repository, bentonite has been selected for using as buffer/backfill materials. For evaluation of long-term performance of an artificial barrier, it is very important to investigate the buffering properties of bentonite under thermo-hydro- mechanical- chemical (THMC) coupled processes. 

 

Objective

1) To investigate the elementary property of compacted bentonite under THMC coupling conditions; 2) to evaluate the long-term performance of an artificial barrier system in a deep repository.

 

Approach

Laboratory tests including elementary tests and mock-up modeling tests, as well as numerical simulation method were employed for the investigation.

 

Significant Results and Potential Impact

1) hydraulic properties were determined under THM coupling conditions, related models for SWRC, saturated hydraulic conductivity and unsaturated conductivity were developed and verified; 2) mechanical properties of compacted bentonite under THM coupling conditions were tested and analyzed; and 3) influences of chemical effects on behavior of compacted bentonite were investigated, corresponding results were obtained and reported.  

 

Principal Investigator:

Weimin Ye, Yonggui Chen, Bao Chen and Bin Ye.

 

Funding

National Natural Science Foundation of China (40728003, 40772180, 40802069, 41030748, 41272287, 41422207), China Atomic Energy Authority (Project [2007]831, [2011]1051).

 

Key Publications

Ye WM*, Xu L, Chen B. Chen Y. G., Ye B., Cui Y. J.. An approach based on two-phase flow phenomenon for modeling gas migration in saturated compacted bentonite. Engineering Geology . Volume 169, 4 February 2014, Pages 124–132.

Ye WM*, N.C. Borrell, J.Y. Zhu, B. Chen, Y.G. Chen. Advances on the investigation of the hydraulic behaviour of compacted GMZ bentonite. Engineering Geology 169 (2014) 41–49.

YE WM*, WAN M., Chen B., Chen Y. G., CUI Y. J., Wang J. An Unsaturated Hydraulic Conductivity Model for Compacted GMZ01 Bentonite with Consideration of Temperature. Environmental Earth Sciences. Volume 71, Issue 4 (2014), Page 1937-1944

X.L. LAI, S.M. WANG, W.M. YE*, Y.J. CUI. Experimental investigation on the creep behavior of an unsaturated clay. Canadian Geotechnical Journal, 2014. 51: 621-628

W. M. Y E*, F. ZHANG, B. CHEN, Y. G. CHEN, Q. Wang, Y. J. CUI. Effects of salt solutions on the hydro-mechanical behaviour of compacted GMZ01 Bentonite. Environmental Earth Sciences. 2014. DOI: 10.1007/s12665-014-3169-x

W.M. YE*, X.L. LAI, Q. WANG, Y.G. CHEN, B. CHEN, Y.J. CUI. An experimental investigation on the secondary compression of unsaturated GMZ01 bentonite. Applied Clay Science, Volumes 97–98, August 2014, Pages 104–109

W.M. Ye*, Z. J. Zheng, B. Chen, Y.G. Chen, Y.J. Cui, J. Wang. Effects of pH and temperature on the swelling pressure and hydraulic conductivity of compacted GMZ01 bentonite. Applied Clay Sciences. 2014, 72:2621-2630

Wan M, Ye WM*, Chen YG, Cui YJ, Wang J. Influence of temperature on the water retention properties of compacted GMZ01 bentonite. Environmental Earth Sciences. 2014. DOI: 10.1007/s12665-014-3690-y

Ye WM*，Zhang YW, Chen Y. G.; Chen, B.; CUI Y. J.. Experimental investigation on the thermal volumetric behaviour of highly compacted GMZ01 Bent. Applied Clay Science, Volume 83-84, issue (October, 2013), p. 210-216

 

Fig. 1. Self-designed experimental setup for swelling pressure and saturated hydraulic conductivity test with temperature control

Figure 2. Schematic view of suction-temperature controlled oedometer cell

 

Figure 3. Thermal volume changes under heating-cooling cycle at constant suctions under a vertical pressure of 0.1 Mpa

 

Fig.4. Total strain develops with time for GMZ01 bentonite cyclically infiltrated with CaCl2 solution and De-ionized water