Modeling of Excavation Damaged Zone through the strain localization approach in Boom clay

peer reviewe

Coupled modeling of Excavation Damaged Zone in Boom clay: Strain localization in rock and distribution of contact pressure on the gallery’s lining

Around galleries excavated at depth in geological media, the creation of a damaged zone with significant irreversible deformation is generally unavoidable. In the case of a geological disposal system for high-level radioactive waste, the resulting change in the host rock properties in this damaged zone may potentially be important with respect to the long-term evolution and the performance of that system. In this context, predicting the extent of the so-called Excavation Damaged Zone (EDZ) and, possibly, the fractures' network topology remains a challenge. This study is aimed to simulate numerically the extension of this zone at the large scale's excavation, around the Connecting gallery (HADES URL, Mol, Belgium), in Boom clay host rock through analyzing the evolution of strain localization in shear bands mode. To realistically model the involved phenomena, the concrete lining is considered on the gallery wall highlighting its impacts on the evolution of convergence and EDZ around the gallery. The focus of the current paper is made on analyzing the coupled hydro-mechanical behavior of Boom clay host rock during and after the gallery excavation with respect to the evolution of localized shear bands around the gallery. This study is accompanied by the analysis of the contact mechanism on the interface between the clay massive and the lining. The obtained results reveal some interesting features regarding the contact phenomenon relatively to the evolution pattern of shear bands within the clay around the gallery. To assess the reliability of the proposed approach, a discussion on some in-situ observations during the gallery's construction is also performed based on which a good agreement is found between the in-situ evidence and simulated results

Conflict effects of autophagy on cellular senescence in advanced ages: A systematic review

Introduction: Recently, autophagy as a highly conserved catabolic intracellular process is considered a promising therapeutic target, particularly in pathological alternations under aging conditions. This systematic review was designed to qualitatively analyze the interaction between autophagy and aging in various organs of animal models. Methods: Based on our primary search, 9478 articles were identified, and following the screening, ultimately, 80 full texts were included to proceed with further analysis. Next, using SPSS software, data analysis of autophagy and aging-related markers and autophagy alternation throughout aging, was performed. Results: Despite debatable results, we established that the most of studies showed that the autophagy process reduced in different aged organs significantly. Conclusion: The outcomes demonstrated that autophagy induction during aging was inferior to those reports that indicated the therapeutic potential of autophagy. Taken together, it should be considered that autophagy inducers could be counted as anti-aging agents

Identifying the Challenges of Users in Using the Services of Electronic Health Platforms

Introduction: In recent years, especially with the spread of the COVID-19 disease, the use of electronic health services has increased greatly. Along with the growth and development of the use of electronic services among users, the concern about ethical and legal issues increases. The purpose of this article was to review the current state of electronic health provision by active platforms in this field and to identify the challenges and problems of users in using these services to achieve the desired state. Method: This qualitative study was conducted using the content analysis method. User comments were collected in Bazaar and Myket mobile applications. Then, using the purposeful sampling method, 300 selected comments containing users' difficulties were analyzed by qualitative content analysis method based on the six steps proposed by Graneheim & Lundman using MAXQDA software. Results: The most important problems reported by users of e-health services fall into two main categories: issues related to care and issues related to the service provider's platform; these difficulties are classified into six subcategories, including doctor-patient relationships, the standard of care, platform quality, user feedback, responsibility, and service tariff. Among the user comments, the most dissatisfaction was associated with the subcategory of the platform's responsibility and accountability (especially the issue of not receiving services despite paying, poor support, and no refunds), followed by issues related to the standard of care. Conclusion: The results of the present analysis can help policymakers with appropriate legislation and regulation and help business managers with solving identified problems. It also increases user satisfaction and trust

Shear banding simulation in clay rock around an underground opening, and its contact mechanism with the gallery’s lining

peer reviewe

From some obscurity to clarity in Boom clay behavior: Analysis of its coupled hydro-mechanical response in the presence of strain localization

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 work, focusing on the Boom Clay formation as the reference potential host rock in Belgium. Dealing with this purpose, providing a state of knowledge on the hydro-mechanical behavior of Boom Clay, and validating a set of parameters which could realistically reproduce its response through the numerical modelings are firstly addressed as the requisites. Moreover, a special focus is made on the dilatation factor of the rock, commonly described through the dilatancy angle parameter. Correct estimation of the dilatant behavior of a rock has an essential role in a realistic simulation of its volumetric behavior, fracturing threshold during the rock deformation process and its post-failure response. Therefore, a new formula is developed for consideration of the variable dilatancy angle, incorporated into an internal frictional elasto-plastic hardening/softening model, within the LAGAMINE finite element code. This development overcomes the inconveniences associated to using a constant dilatancy angle, for instance encountered in our numerical simulations of some laboratory small-scale tests as well as a large-scale excavation. This study then focuses more particularly on simulation of EDZ extension at the large scale excavation, around the Connecting gallery (in the HADES URL, Mol, Belgium), through analyzing the evolution of strain localization in shear bands mode. The modeling takes into account of the initial anisotropic stresses, mechanical cross-anisotropy, anisotropic permeabilities, and gravity effects. As a result, an eye-shape extension of EDZ accompanied by an anisotropic convergence of the rock is predicted. A coupled analysis addresses the pore water pressure distribution during the excavation period and in long-term while no more evolution of the localized shear bands is predicted. To assess the reliability of the numerical results, some available in-situ measurements and observations, within the clay, during the gallery's construction and afterwards are precisely analyzed, and then compared with the corresponding numerical predictions. As a result, a good agreement is found between the in-situ data and simulated results. Moreover, the above study is integrated with a particular analysis of the contact mechanism on the interface between the clay and the gallery's lining. Thence, the coupled interface element is introduced to deal with the contact phenomenon. The obtained results reveal some interesting features regarding the development of contact pressure on the interface linked to the evolution pattern of strain localization within the clay around the gallery. Furthermore, with regard to the own lining behavior, a development of the modeling with the aim of consideration of a discontinuous lining (made of the segments as the real case) is performed. We propose an approach to realistically reproduce the response of the lining's segments and their contact phenomena in the course of a long-term simulation. Defining the interface elements between the neighboring segments, with respect to the real installation procedure of the lining during the gallery construction, this process is aimed to be simulated through some evolution of the contact pressure on the segments' interfaces. As a result, a considerable improvement is achieved in reproducing the in-situ measurements provided in the lining. The numerical and measured evolution of strain and displacement are in a good agreement