Geomechanics for Energy and the Environment最新文献

{"title":"A numerical analysis of Thermo–Hydro–Mechanical behavior in the FE experiment at Mont Terri URL: Investigating capillary effects in bentonite on the disposal system","authors":"Taehyun Kim ,&nbsp;Chan-Hee Park ,&nbsp;Changsoo Lee ,&nbsp;Jin-Seop Kim ,&nbsp;Eui-Seob Park ,&nbsp;Bastian Graupner","doi":"10.1016/j.gete.2024.100597","DOIUrl":"10.1016/j.gete.2024.100597","url":null,"abstract":"<div><div>We investigated thermo–hydro–mechanical (T-H–M) coupled behavior observed during the full-scale heater emplacement experiment at the Mont-Terri underground research laboratory conducted in the Opalinus clay as part of the DECOVALEX-2023 Task C project. Utilizing the OGS-FLAC simulator, we created a three-dimensional model to simulate multiphase flow in the experiment, applying extended Philip and de Vries’ model and incorporating the anisotropic T–H–M properties of the Opalinus clay. The simulation, which included a ventilation process, spanned five years of heating experiments and successfully replicated the measured temperature, pore pressure, displacement, and relative humidity results in bentonite and host rock during the experiment. The analysis revealed that capillary pressure significantly influenced the pore pressure change in the host rock near the tunnel, while thermal pressurization became dominant with increasing distance. Consequently, we conducted a sensitivity analysis on a simplified model to evaluate the effect of capillary pressure on the disposal system. Capillarity is a dominant factor for the multiphase flow depending on the distance from the heat. Variations in capillary pressure were observed depending on the gas entry pressure and water retention model, indicating that the capillarity of unsaturated bentonite could inherently affect the T–H–M results within the disposal system.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100597"},"PeriodicalIF":3.3,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142318598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical investigation of the thermal hydrofracturing behavior of the Callovo-Oxfordian claystone","authors":"Carlos Plúa ,&nbsp;Minh-Ngoc Vu ,&nbsp;Gilles Armand ,&nbsp;Zady Ouraga ,&nbsp;Zhan Yu ,&nbsp;Jian-Fu Shao ,&nbsp;Qianyun Wang ,&nbsp;Hua Shao ,&nbsp;Tsubasa Sasaki ,&nbsp;Sangcheol Yoon ,&nbsp;Jonny Rutqvist ,&nbsp;Fei Song ,&nbsp;Stefano Collico ,&nbsp;Antonio Gens ,&nbsp;Louise Bruffell ,&nbsp;Kate Thatcher ,&nbsp;Alexander E. Bond","doi":"10.1016/j.gete.2024.100596","DOIUrl":"10.1016/j.gete.2024.100596","url":null,"abstract":"<div><div>This study addresses the thermal hydrofracturing behavior in claystone within the context of the high-level and intermediate-level long-lived radioactive waste disposal. The heat generated by the waste packages will lead to a temperature increment within the host formation, inducing a pore pressure build-up essentially due to the difference between the thermal expansion coefficient of the pore water and that of the solid skeleton. If the induced pore pressure build-up is too high, the host formation will experience tensile stresses, potentially exceeding its tensile strength and resulting in fracturing. Understanding of these processes and improving numerical models to reproduce them will help the design, optimization, and safety of the repository. Additionally, it will contribute to demonstrating robustness by showing that such processes are not expected to occur at the repository scale.</div><div>This study was conducted as part of the DECOVALEX-2023 project and synthesizes the efforts of six research teams modelling laboratory thermal extension tests conducted on Callovo-Oxfordian claystone (COx) samples, as well as an in-situ thermal hydrofracturing experiment conducted at the Meuse/Haute-Marne Underground Research Laboratory in France. The teams used different numerical codes with different approaches, including continuum and discrete approaches, to model these two tests. The laboratory tests were used to calibrate the teams’ models, such as the fracturing criterion. The teams considered a thermo-hydromechanical formulation under saturated conditions. One of the key features of their models was the incorporation of changes in the hydraulic properties of the COx through hydromechanical coupling.</div><div>The approaches developed by the teams demonstrated their capability to analyze and reproduce fracture initiation in the COx in terms of time of occurrence and location based on their respective stress analyses. However, attempts to reproduce fracture aperture or fracture propagation were less accurate and remain areas for future research, which were beyond the scope of this study.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100596"},"PeriodicalIF":3.3,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A complete experimental study on hard granites: Microstructural characterization, mechanical response, and failure criterion","authors":"Stéphane Dumoulin ,&nbsp;Isabelle Thenevin ,&nbsp;Alexandre Kane ,&nbsp;Ahmed Rouabhi ,&nbsp;John-Paul Latham ,&nbsp;Emad Jahangir ,&nbsp;Hedi Sellami","doi":"10.1016/j.gete.2024.100592","DOIUrl":"10.1016/j.gete.2024.100592","url":null,"abstract":"<div><p>This study, performed during the ORCHYD European project, devoted to drilling deep geothermal boreholes, has many potential applications to mechanical studies. It gathers geological descriptions of three outcropping granites from Scandinavia (Kuru Grey and Red Bohus) and from the South of France (Sidobre). Microstructural investigations include optical microscopy and X-ray tomography. The three granites chosen contain grain sizes that cover all the common ranges for granites: fine, medium and coarse. As the mineral phase volume fractions are similar in each, the grain defects and grain boundaries are carefully studied in an attempt to understand the physical and mechanical properties of the three granite rock samples measured at laboratory specimen scale. The rocks are tested for UCS, BTS and triaxial compressive strength with confining pressures up to 225 MPa or/and high strain-rates up to 10³/s. The micro-structural parameters influencing the mechanical behaviour are highlighted. Test results show that the effect of confining pressure and strain-rate on compressive strength are uncoupled. These effects are then estimated independently, and a fracture criterion in compression accounting for both variables is proposed for the family of very hard granites. This criterion takes as a single reference strength measure for each rock the deviatoric stress at failure under 20 MPa confining stress in the quasi-static regime. It is then compared with existing datasets for which both quasi-static and dynamic regime data are available. This complete data set on these three very hard granites (UCS ∼ 200 MPa), together with a synthesis for failure prediction, has the potential to inform numerous rock engineering projects and be of value to the scientific community.</p></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100592"},"PeriodicalIF":3.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2352380824000595/pdfft?md5=a9ab308b23241c7272095cdbad5eba81&pid=1-s2.0-S2352380824000595-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on energy consumption and failure mechanism of water-saturated coal sample during impact cracking","authors":"Zhoujie Gu ,&nbsp;Rongxi Shen ,&nbsp;Zhentang Liu ,&nbsp;Xin Zhou ,&nbsp;Xiulei Wang","doi":"10.1016/j.gete.2024.100593","DOIUrl":"10.1016/j.gete.2024.100593","url":null,"abstract":"<div><p>To uncover the mechanism of energy dissipation in coal samples when subjected to both water and dynamic load, the damage patterns and energy absorption properties of coal samples in their natural and saturated states were investigated and analyzed through Hopkinson impact experiments. The results of the study show that the mass and wave velocity of the natural coal samples show an increasing trend when they are saturated with water. And the mass and wave velocity increase by 6.35 % and 21.42 % respectively. The coal sample's level of fragmentation and dynamic strength exhibited a positive correlation with the velocity (1 m/s-5.69 m/s) of impact. When subjected to dynamic loads, both natural and water-saturated coal samples primarily undergo splitting, fracturing, and crushing. Compared with natural coal samples, saturated water coal samples show greater degree of crushing and lower mechanical strength. The dynamic strength of saturated coal sample at 5.25 m/s (15.66 MPa) decreased by 33.86 % compared with that at 5.69 m/s (23.68 MPa). The mean size of particles in coal samples, both in their natural state and when saturated with water, had an linear reduction relationship with impact speed. Conversely, the fractal dimension, which represents dissipation, had a direct relationship with impact speed. The fractal dimensions of dry and saturated coal samples are distributed in the ranges of 1.56–2.08 and 1.65–2.1, respectively. And the dissipative energy of natural coal samples between 1.09 m/s and 5.67 m/s is about 0.039 J/cm³-0.175 J/cm³, and that of saturated coal samples between 1 m/s and 5.25 m/s is about 0.034 J/cm³-0.088 J/cm³. The surface energy of coal samples was analysed and calculated, and an energy consumption prediction model was proposed to predict the energy consumption of coal samples after dynamic crushing.</p></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100593"},"PeriodicalIF":3.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of convection on the thermal storage performance of energy tunnels","authors":"Annik Schaufelberger ,&nbsp;Lyesse Laloui ,&nbsp;Alessandro F. Rotta Loria","doi":"10.1016/j.gete.2024.100595","DOIUrl":"10.1016/j.gete.2024.100595","url":null,"abstract":"<div><p>The decarbonization of the built environment requires rapid growth in energy storage solutions due to the intermittent nature of most renewable energy sources. This paper focuses on the efficacy of so-called energy tunnels (i.e., tunnels equipped with pipe heat exchangers) used for underground thermal energy storage. By harnessing a 3-D thermo-hydraulic finite element model validated against full-scale experimental data, this work specifically explores seasonal, medium-temperature, thermal energy storage operations of energy tunnels. Numerical simulations are performed to unravel the influence of convection resulting from groundwater flows and airflows on the thermal energy storage performance of energy tunnels. The analyses address the impact of different groundwater flow velocities, air temperatures, and airflow velocities on the thermal losses and storage efficiency of energy tunnels used as thermal batteries. The study discourages underground thermal energy storage in the presence of convection due to significant heat losses. It shows that thermal energy storage operations via energy tunnels are feasible in site conditions characterized by no groundwater flow, limited temperature differentials between the heat carrier fluid circulating in the pipe heat exchangers and the surroundings, and thermal insulation on the tunnel intrados.</p></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100595"},"PeriodicalIF":3.3,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142168528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predicting the Representative Elementary Volume by determining the evolution law of the convergence cone","authors":"Sijmen Zwarts,&nbsp;Martin Lesueur","doi":"10.1016/j.gete.2024.100594","DOIUrl":"10.1016/j.gete.2024.100594","url":null,"abstract":"<div><p>In order to characterise a rock formation prior to subsurface operations, it is required to find a microscale rock volume for which the homogenised property does not fluctuate when the size of the sample is increased; the Representative Elementary Volume (REV). Its determination usually comes at the cost of a large number of simulations, making it overall a computationally expensive process. Therefore, many scientific studies have been dedicated to optimising the process of finding REV. Using statistical numerical methods, it is shown that the fluctuation of the effective property corresponds overall to a cone-like shape convergence. We suggest determining the generic evolution law of the cone of convergence, which can be used to predict the size of the REV and the effective physical property. This study is based on simulations of Stokes flow through idealised microstructures from which the permeability is upscaled. By tracing and plotting the convergence of permeability for multiple samples, the full cone of convergence appears. The cone shows exponential growth and decay, converging towards the effective permeability of the microstructure. By fitting a log-normal distribution on the collected data points, we show that the generic evolution law of the cone of convergence can always be described with two parameters, independently of the porosity. We show that the determined law of the cone also applies to real microstructures, despite the presence of natural heterogeneities. The new method allows us to reduce the computational costs of finding all characteristics related to REV by simulating several subsamples rather than the full-sized sample, unlocking thereby high-resolution samples which are often too computationally expensive. The use of a statistical model provides quantification of the precision level we can obtain on the REV determination.</p></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100594"},"PeriodicalIF":3.3,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Small-scale physical modelling of vertically loaded, cyclically thermally-activated helical piles","authors":"Mohammadreza Bashiri ,&nbsp;Mahmoud Ghazavi ,&nbsp;Peter J. Bourne-Webb","doi":"10.1016/j.gete.2024.100589","DOIUrl":"10.1016/j.gete.2024.100589","url":null,"abstract":"<div><p>To investigate the use of thermally-activated helical piles in shallow geothermal energy systems, a 1-g modelling study was conducted. Helical piles with either a single- or double- helix were installed in a medium dense, dry sand, and subjected to mechanical, thermal only and thermo-mechanical loading. The results indicate that during the thermal tests (1 – 3 cycles), a small upwards residual displacement was observed and pile head movements ranged between about 90% and 100% of the free expansion of the pile shaft above the shallowest helix, suggesting that the helices fixed the shaft and little restraint was offered by the surrounding soil. In the thermo-mechanical tests (30 thermal cycles), the pile head developed irrecoverable settlement as a function of the number of helices (more helices, less settlement) and initial load (higher load, greater settlement). No significant alteration in pile axial stiffness or resistance was found for piles with zero mechanical load that underwent only a few thermal cycles; however, an increase in stiffness and resistance, beyond that due to inherent variability in the test setup, was observed for piles with an initial load and following a large number of thermal cycles. The testing of thermally-activated helical piles in sand has confirmed that the response is similar to conventional piles and that thermal ratcheting effects can be managed by the application of suitable margins of safety in design and/or the use of multi-helix piles.</p></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100589"},"PeriodicalIF":3.3,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-scale constitutive modeling of the brittle–ductile transition behavior of rocks with microcracks and two populations of pores","authors":"Sili Liu ,&nbsp;Qizhi Zhu ,&nbsp;Jin Zhang","doi":"10.1016/j.gete.2024.100591","DOIUrl":"10.1016/j.gete.2024.100591","url":null,"abstract":"<div><p>The present paper is devoted to multi-scale constitutive modeling of the brittle–ductile transition in rocks. The rocks are considered as heterogeneous media composed of solid phase weakened by microcracks at the microscale and two different populations of pores at the micro and mesoscales. A Drucker–Prager type criterion is first formulated considering microcracking-induced damage in the solid phase. By means of a two-step modified secant variational method, this criterion is then adopted to derive a micro–macro model for double porous medium taking into account the effects of pores. Considering that the operative deformation mechanism in brittle rocks is microcracking, the Drucker–Prager type microcrack damage model is applied to describe the transition of three typical brittle rocks from brittle faulting to dilatant ductile flow by establishing a linear relation between the critical damage caused by microcrack propagation and confining pressure. By introducing an appropriate plastic hardening law and taking into account the influence of confining pressure on plastic hardening parameter and dilatancy coefficient, the micro–macro model for porous rocks is applied to describe the transition from brittle faulting to compactive ductile flow in two typical porous rocks. Comparisons between numerical simulations and experimental data show that the main features of brittle–ductile transition of two types of rocks are well captured by the proposed model.</p></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100591"},"PeriodicalIF":3.3,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142149527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative assessment of well leakage, part I: Cement stress evolution","authors":"A. Moghadam,&nbsp;M. Loizzo","doi":"10.1016/j.gete.2024.100586","DOIUrl":"10.1016/j.gete.2024.100586","url":null,"abstract":"<div><p>A damaged cement sheath in wells can open a leakage pathway to shallow freshwater aquifers and atmosphere. Quantitative assessment of leakage along wells has become an area of interest for both the industry and the regulatory bodies. The well leakage can be of importance in both active and legacy wells. In order to estimate leakage through cement sheaths, the size of the leakage pathway and the damage in the cement sheath must be estimated. In this work, we have developed a hydro-thermo-mechanically coupled near-well model that aims to calculate the evolution of cement’s stress as it cures. This process takes into account the cement’s gradual increase in stiffness, chemical shrinkage, and the heat of hydration. The results are verified using lab measured cement stress and pore pressure data from the literature. A case study was developed based on a low-enthalpy geothermal doublet in the Netherlands. The results show that during the cold water injection, an outer microannulus may open to 60 µm. The presence of an external source of water and formation stiffness are of significant importance in determining the damage to the cement sheath. The heat of hydration in cement increases the temperature of cement during curing. The subsequent drop in temperature due to drilling or completion reduces the cement stress and exacerbates the damage to the cement sheath. The producer well may not form a microannuli, however shear and cyclical failure may be of higher likelihood. The modelling framework presented here allows for estimation of annular cement stress in the well. The analysis provides quantitative estimates of the size of the leakage pathway along a well that can be used to estimate well leakge. Quantitative estimate of well leakage provides crucial information for quantitative risk analysis and provides a framework to optimize well operations to minimize leakage risk.</p></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100586"},"PeriodicalIF":3.3,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142157886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Offshore geotechnical challenges of the energy transition","authors":"Susan Gourvenec","doi":"10.1016/j.gete.2024.100584","DOIUrl":"10.1016/j.gete.2024.100584","url":null,"abstract":"<div><p>Offshore wind is the most mature of the offshore renewable energy technologies and has a significant role to play in the energy transition. 2000 GW of offshore wind capacity is anticipated globally by 2050 in order meet the targets of the Paris Agreement; 35 times the current installed capacity. The pace and scale of offshore wind ambitions to support the energy transition present a range of challenges for the offshore geotechnical sector and the broader offshore wind sector. Challenges extend across the life-cycle of projects from marine spatial planning, site investigation, design, manufacturing, installation, operation and decommissioning, and across the supply chain regarding availability of raw materials for foundations, anchors and mooring systems, vessels and equipment for site investigation and installation, and trained geotechnical personnel. This paper identifies five key challenges and sets out the necessary shifts in technology, culture and practice in geotechnical engineering to achieve the ambitious targets to deliver offshore wind at the pace and scale required for the energy transition. The paper closes with a reflection on the consequence of delaying or not meeting net-zero targets, and thus identifying the urgency for these shifts in technology, culture and practice to be developed and adopted.</p></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"39 ","pages":"Article 100584"},"PeriodicalIF":3.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2352380824000510/pdfft?md5=a8c213ea17d3d9eb8484320b0a0b7e0e&pid=1-s2.0-S2352380824000510-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142098690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}