Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal (original) (raw)
Related papers
2015
Deep disposal of the high-level and high-lived radioactive wastes in the potential geological formations is envisaged as a possible solution in the framework of long-term management of these wastes. The argillaceous materials, namely Boom Clay, are potential to constitute the natural barrier aimed at confining the nuclear waste and protecting the biosphere from it. Around galleries excavated at depth in these media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. A considerable change in the host rock properties could be likely resulted in this zone, which may potentially be important with respect to the long-term evolution and the performance of the system. In this context, a paramount interest addresses characterization of the so-called Excavation Damaged Zone (EDZ), predicting its extent, and development of localized fracturing during and after the underground excavation in the host rock. This constitutes the foundation of this w...
Engineering Geology, 2002
Long-term changes in mechanical properties of clays induced by heating are investigated based on findings at Orciatico site of natural analog of nuclear waste disposal. To quantify the extent of such changes, a chemo-thermoplastic model for illitization and re-smectitization of clays [Int. J. Plast. (2000)] is used. The model is an extension of Cam-clay model. Identification of parameters is presented for the material from one peripheral borehole where temperatures developed in clay near the contact were in the analogy range. Short-term heating experiments on previously thermally unaffected specimens were used to identify thermal softening characteristics. Apparent maximum past precompression stress was determined throughout the borehole. Hypothetical history of the clay in the borehole including pre-loading, heating, cooling and mineralogical reaction was reconstructed, and the apparent maximum past precompression stress data were used to identify the characteristics of chemical softening function describing the long-term clay transformations.
Laboratory hydro-mechanical characterisation of Boom Clay at Essen and Mol
Physics and Chemistry of the Earth, Parts A/B/C, 2011
Boom Clay has been selected as a potential host rock formation for the geological disposal of radioactive waste in Belgium. In the present work, the hydro-mechanical behaviour of Boom Clay samples from the borehole Essen-1 at a depth of 220-260 m and from HADES that is the underground rock laboratory at Mol in Belgium, at 223-m depth was investigated in the laboratory by performing low pressure oedometer tests (vertical effective stress ranging from 0.05 to 3.2 MPa), high pressure oedometer tests (vertical effective stress ranging from 0.125 to 32 MPa), isotropic consolidation tests (confining effective stress ranging from the in situ stress to 20 MPa) and triaxial shear tests. It has been observed that the mineralogy, geotechnical properties and hydro-mechanical behaviour of Boom Clay from Essen at 227-m, 240-m and 248-m depths are similar to that of Boom Clay from Mol. As in the case of Boom Clay at Mol, the failure envelope of Boom Clay at Essen in the p 0 -q plane is not linear. The slope of the portion beyond the pre-consolidation stress of Boom Clay from Essen is almost the same as that from Mol, suggesting a similar internal friction angle of about 13°. The compression curves (void index I v versus logarithm of vertical stress) beyond the pre-consolidation stress are the same for both samples from Mol and Essen, and situated between the intrinsic compression line (ICL) and the sedimentation compression line (SCL). The yield stress determined from oedometer tests seems to be stress-path dependent and lower than the pre-consolidation stress. Thus determining the over-consolidation ratio (OCR) using the yield stress value would lead to an incorrect estimate. From a practical point view, the laboratory test results from Essen and their comparison with those from Mol provide important information regarding the transferability of knowledge on Boom Clay at different sites, taking into account the fact that most investigations have been carried out on Boom Clay at Mol.
THM STUDY OF CLAY ROCKS FOR NUCLEAR WASTE STORAGE
2020
Argillaceous rocks, specifically stiff sedimentary clays, form the geological basis for numerous civil engineering projects. Recently, there has been heightened interest in these materials as potential host media for underground repositories of high-level radioactive waste (HLW). This possibility has led to the establishment of several underground laboratories. Among the various topics explored in these Underground Research Laboratories (URLs), the thermo-hydromechanical (THM) behavior of the host rock is of primary concern for the current research. In situ observations have identified numerous coupled THM processes involved in the operation of an HLW repository.
Gas migration in deep argillaceous formations : Boom clay and indurated clays
2017
Deep geological disposal remains the preferred option at present for the management of long-living and heat-emitting radioactive waste, which consists of confining the waste during a very long period (several hundreds of thousands of years) by placing them in a deep geological formation. Therefore, the understanding of the long-term behaviour of formations is becoming a key issue to ensure the feasibility of the geological disposal facilities, particularly regarding the generation and migration of gases. The present PhD work aims at better understanding the complex hydro-mechanical response of different argillaceous formations to gas migration process. To this end, gas flow through Boom Clay (one of the potential candidate plastic Paleogene clay formations to host nuclear waste in Belgium) has been deeply investigated on the basis of laboratory experiments at different scales and their numerical modelling. This main study has been complemented by presenting tests on two indurated an...