Geomechanics for Energy and the Environment最新文献

{"title":"Functional analysis of the constitutive role of temperature in compacted bentonites","authors":"Vicente Navarro ,&nbsp;Gema Urraca ,&nbsp;Laura Asensio","doi":"10.1016/j.gete.2024.100620","DOIUrl":"10.1016/j.gete.2024.100620","url":null,"abstract":"<div><div>A thermodynamically consistent expression is derived for the functional structure of effective stress understood as the work conjugate of elastic strain. The study, focussed on compacted clays, is valid for both non-isothermal conditions and constant temperature. As a result, it is found that there is no evidence to assume a direct dependence of the effective stress on temperature. Therefore, it is consistent to follow the usually employed strategies based on evaluating the implicit dependence through air pressure, macrostructural liquid pressure and macrostructural degree of saturation.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100620"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743895","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":"In situ static elastic properties assessment and validation with pressuremeter testing using a formation tester tool","authors":"Jean E. Elkhoury ,&nbsp;Thomas Bérard ,&nbsp;Jean Desroches ,&nbsp;Emilie Peyret ,&nbsp;Romain Prioul ,&nbsp;Eleonora Crisci ,&nbsp;Rodney Garrard ,&nbsp;Silvio B. Giger","doi":"10.1016/j.gete.2024.100619","DOIUrl":"10.1016/j.gete.2024.100619","url":null,"abstract":"<div><div>Pressuremeter testing (PMT) is a formation test that consists of inflating a cylindrical packer inside a borehole while measuring the radial deformation or injected fluid volume as a function of packer pressure. Provided that the stiffness of the packer measuring system is known and large enough compared to that of the formation, changes in packer pressure associated with changes in injected fluid volume provide a direct measurement of formation stiffness. In turn, the in situ static shear modulus is obtained from the formation stiffness at a length scale similar to that of the packer. Here, we report on the first field-scale campaign of PMTs in deep boreholes performed using a wireline formation tester (WFT) tool. We carried out PMT measurements as part of the characterization and appraisal of potential sites for a deep geological repository for radioactive waste in Switzerland. We performed multiple PMT inflation cycles to infer in situ static shear moduli at six stations spread across four boreholes. PMT-derived static shear moduli results were consistent with static shear moduli derived from sonic logs using independent dynamic-to-static elastic moduli transformations. PMT-derived static shear moduli and laboratory-derived static elastic moduli using samples from coring performed at the depths of the PMT stations were consistent, with slightly lower laboratory values. Furthermore, we report dynamic-to-static shear moduli transformations by using laboratory-scale data obtained on cores and field-scale derived from sonic logs and PMT. We observed differences between static and dynamic shear moduli derived from laboratory scale using cores and field scale using sonic logs and PMT. We report linear trend slopes of about 0.5 for the laboratory data and 0.7 for the field data. These first results show the viability of in situ PMT in deep boreholes with a WFT tool, as it can be performed at multiple depths in a single run, in a time-efficient manner, and in combination with micro-hydraulic and sleeve fracturing stress tests for an integral approach to in situ geomechanical assessment.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100619"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164577","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":"Influence of mechanical strength on gas migration through bentonite: Numerical analysis from laboratory to field scale","authors":"Jung-Tae Kim ,&nbsp;Changsoo Lee ,&nbsp;Minhyeong Lee ,&nbsp;Jin-Seop Kim ,&nbsp;E. Tamayo-Mas ,&nbsp;J.F. Harrington","doi":"10.1016/j.gete.2024.100614","DOIUrl":"10.1016/j.gete.2024.100614","url":null,"abstract":"<div><div>Understanding the gas movement phenomenon within the deep geological repository is essential for assessing the disposal system’s long-term stability. The primary gas transport mechanism through the bentonite is dilatancy-controlled flow, which differs from gas flow in general porous media. This flow is characterized by gas movement through microcracks created under relatively high gas pressure conditions, and the intrinsic permeability, air-entry pressure, and mechanical strength of the medium change due to the generation and propagation of these microcracks. Therefore, dilatancy-controlled flow cannot be simulated using the classical two-phase flow modeling technique. This study constructed the H<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span>MD (two-phase hydraulic-mechanical-damage) numerical model by combining a damage model to simulate material degradation and the resulting change in intrinsic permeability with a classical two-phase flow model. In addition, the numerical model was tested against a 1D laboratory gas injection test investing gas flow mechanisms in the buffer, and a sensitivity analysis was performed on tensile strength, a key factor in the damage model for gas movement phenomenon. In the validation study, the proposed model successfully simulated the key features observed in the test: rapid stress and pressure increase trends, changes in intrinsic permeability due to damage, and the resulting flow rate. In addition, the effect of heterogeneity on the strength characteristics of each material and interfaces between materials was analyzed through field-scale test simulations, and the applicability of the model to upscaling analysis was examined. The study of heterogeneity effects confirmed that incorporating the strength characteristics of interfaces accurately simulates the gas flow path observed in actual tests. However, the model overestimated the gas flow before the gas breakthrough and underestimated the evolution of the damaged area within the buffer. Therefore, additional research on relative permeability and mechanical constitutive models is needed to improve the reliability of the current model.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100614"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164650","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":"Modelling of mass transport in fractured crystalline rock using velocity interpolation and cell-jump particle tracking methods","authors":"Chieh-Chun Chang ,&nbsp;Yi-Fu Chiou ,&nbsp;Yu-Hsiang Shen ,&nbsp;Yun-Chen Yu","doi":"10.1016/j.gete.2024.100615","DOIUrl":"10.1016/j.gete.2024.100615","url":null,"abstract":"<div><div>In this study, two particle tracking methods, velocity interpolation, and cell-jump, were employed to simulate tracer transport in fractured crystalline rock. The models, belonging to DECOVALEX-2023 Task F1, included one considering only the influence of deterministic (major) fractures, and another considering both deterministic and stochastic (background) fractures. The simulations involved converting fracture properties into equivalent hydraulic parameters for each three-dimensional grid, simulating steady-state flow fields, and evaluating transport parameters using particle tracking methods. Using transport parameters, one-dimensional transport pathways were simulated for evaluating mass transport of tracers considering non-reactive, decay, and adsorption. Moment analysis was then utilized to quantify breakthrough curves and compare the performance of the two particle tracking methods. The conclusion is that the cell-jump method, despite facing issues with numerical dispersion that results in a broader distribution of particle trajectories, demonstrates advantages in providing relative shorter mean breakthrough times and less temporal spreading compared to the velocity interpolation (VI) method in cases involving stochastic background fractures. Both methods are limited by the issue of particles entering the matrix due to the application of non-zero permeability for numerical convenience.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100615"},"PeriodicalIF":3.3,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699385","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 modeling of hydro-mechanical processes during hydraulic testing of pre-existing fractures at the Grimsel Test Site, Switzerland","authors":"Josselin Ouf ,&nbsp;Kavan Khaledi ,&nbsp;Philip J. Vardon ,&nbsp;Wen Luo ,&nbsp;Mohammadreza Jalali ,&nbsp;Florian Amann","doi":"10.1016/j.gete.2024.100608","DOIUrl":"10.1016/j.gete.2024.100608","url":null,"abstract":"<div><div>This study presents a fully coupled hydro-mechanical framework for modeling hydraulic shearing in a mesoscale reservoir located at the Grimsel Test Site, Switzerland. The experiment was conducted on a ductile–brittle fault embedded in low-permeable granite. We observe that normal fracture opening increases flow channel recoverably, while fracture sliding locks asperities leading to a non-recoverable increase in flow. To couple these processes, we use a poro-elasto-plastic constitutive framework and employ a permeability function that depends on several parameters, such as dilation angle, in-situ stresses, residual aperture and maximum aperture. Our results capture the recorded pressure responses well, and indicate that the permeability changes by one order of magnitude during the experiment.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100608"},"PeriodicalIF":3.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651374","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":"A finite discrete element approach for modeling of desiccation fracturing around underground openings in Opalinus clay","authors":"Nima Haghighat,&nbsp;Amir Shoarian Sattari,&nbsp;Frank Wuttke","doi":"10.1016/j.gete.2024.100612","DOIUrl":"10.1016/j.gete.2024.100612","url":null,"abstract":"<div><div>Understanding and predicting potential failure mechanisms during the excavation and open drift stages of geological repository construction are among the crucial aspects of performance evaluation and safety assessment of nuclear waste storage facilities. The development of the Excavation Damage Zone (EDZ) and the generation of shrinkage-induced cracks during operational phases are prominent examples of failure mechanisms that can compromise the integrity of the repository systems. This study presents an integrated framework for investigating shrinkage-induced cracking of Opalinus Clay in niches and tunnels. To achieve this, the hybrid Finite Discrete Element Method (FDEM) is employed. The methodology incorporates a two-way staggered hydro-mechanical coupling scheme, where solid phase analysis relies on 2D FDEM and fluid flow is modeled using the nonlinear Richards’ equation and solved via Finite Volume discretization. To account for the effects of EDZ, characterized by a pronounced increase in hydraulic conductivity, a numerical simulation of tunnel excavation is first carried out. The resulting failure pattern around underground openings is then abstracted through the definition of an altered hydraulic conductivity field. Comparison of the numerical results with field observations demonstrates the framework’s ability to capture a wide range of failure mechanisms inherent in various stages of underground repository construction in Opalinus Clay.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100612"},"PeriodicalIF":3.3,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571511","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":"Comparison between new enhanced thermal response test methods for underground heat exchanger sizing","authors":"A. Galgaro ,&nbsp;R. Da Re ,&nbsp;A. Carrera ,&nbsp;E. Di Sipio ,&nbsp;G. Dalla Santa","doi":"10.1016/j.gete.2024.100613","DOIUrl":"10.1016/j.gete.2024.100613","url":null,"abstract":"<div><div>For the efficient design and implementation of a Ground Source Heat Pump (GSHP) system, the local subsoil stands as the core element. Alongside the conventional Thermal Response Test (TRT), recent research has developed improved approaches that garner more detailed information about ground thermal properties. One such technique is the fiber optic-based distributed thermal sensing. It relies on copper wires to thermally stimulate the ground, while optical fibers collect temperature variations over time along the cable. Another pioneering technology, the enhanced GEOsniff (produced by enOware GmbH), enables high-resolution, spatially-distributed representation of subsoil thermal properties along the Borehole Heat Exchanger (BHE) via wireless data transmission. This study compares and discusses data acquired through these two innovative techniques at the new campus for the humanities of the University of Padova, situated in Northern Italy's Eastern Po river plain. The findings are further juxtaposed with conventional TRT results, in terms of thermal conductivity and borehole thermal resistance. The thermal conductivity vertical profiles are also compared with direct measurements conducted on samples. These advanced techniques show promise in aiding the optimization of borehole length design, particularly in geological settings of heightened complexity.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100613"},"PeriodicalIF":3.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142650683","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":"Early and post-stage piping erosion in bentonite buffer materials exposed to groundwater inflow","authors":"Minhyeong Lee ,&nbsp;Chang-Ho Hong ,&nbsp;Ji-Won Kim ,&nbsp;Jinwoo Kim ,&nbsp;Jin-Seop Kim","doi":"10.1016/j.gete.2024.100611","DOIUrl":"10.1016/j.gete.2024.100611","url":null,"abstract":"<div><div>Piping erosion presents a significant concern in engineered barrier system (EBS), contributing to performance uncertainties. However, the early-stage hydration and piping erosion characteristics of calcium-type bentonite under concentrated water inflow conditions are not fully understood. To address this gap, we examined early- and post-stage piping erosion in bentonite buffer materials. Specifically, we focused on the onset and evolution of piping channels with changes in the inflow pressure and their impact on buffer material integrity. Piping experiments were conducted using bentonite in block, granule, and powder forms under constant flow rate conditions. We analyzed the hydraulic-mechanical responses at the bentonite-cell interface, fluctuations in inflow water pressure, and eroded soil mass. Additionally, X-ray computed tomography imaging was utilized to assess the deterioration of buffer materials after piping. The results revealed that early-stage hydration-induced erosion behaviors are contingent upon the state of the bentonite buffer, with compacted blocks exhibiting predominant piping erosion. The rapid pressure buildup and breakthrough is essential in triggering piping erosion in the blocks, while the evolution of piping channels is influenced by the flow rate. Furthermore, severe cracks occurred along with the piping channels under reduced flow rate conditions, creating voids in the buffer amounting to 1.5–3.1 % of its initial volume. These findings provide insights into buffer-rock interfacial interactions in EBS, serving as the basis for in situ disposal experiments and the safe design of disposal repositories.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100611"},"PeriodicalIF":3.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535955","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":"Dam impoundment near active faults in areas with high seismic potential: Case studies from Bisri and Mseilha dams, Lebanon","authors":"A. Yehya ,&nbsp;J. Basbous ,&nbsp;E. Maalouf ,&nbsp;T.S. Nemer","doi":"10.1016/j.gete.2024.100610","DOIUrl":"10.1016/j.gete.2024.100610","url":null,"abstract":"<div><div>Reservoir induced seismicity is caused by stress changes due to the impoundment of water behind dams. In seismically active areas, the presence of critically located active faults makes the impoundment of water behind dams a seismic safety risk. Dam projects in Lebanon have become a soaring example of complacency and negligence that has overlooked the concerns for seismic safety raised over the projects and their high potential of inducing seismicity. In this paper, we use 2D and 3D fully coupled poroelastic modeling to assess the risk of dam impoundment on seismogenic faults located near dam sites in Lebanon. The coulomb failure stresses are calculated along the faults, and their variations are observed in relation to changes in pore pressures and normal stresses. In addition, the expected maximum earthquake magnitudes are computed along those faults. Our results show a high risk for reservoir induced seismicity on faults that are either underneath the reservoir or hydraulically connected to a fault beneath the reservoir. Consequently, the studied dams would present a serious hazard of induced seismicity in time where the region is already at high risk of destructive earthquakes after the catastrophic seismic events that struck Turkey and Syria on 6 February 2023 on the Eastern Anatolian Fault, which is connected to the Dead Sea Transform Fault that passes through Lebanon.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100610"},"PeriodicalIF":3.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535953","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":"AC-assisted microbially induced carbonate precipitation for sand reinforcement: An experimental study","authors":"Angran Tian,&nbsp;Xiaojie Tang,&nbsp;Jing Chen,&nbsp;Manman Hu","doi":"10.1016/j.gete.2024.100609","DOIUrl":"10.1016/j.gete.2024.100609","url":null,"abstract":"<div><div>Microbially induced carbonate precipitation (MICP) is a promising method for transforming natural soils into a rock-like material, enhancing soil strength and creating an environmentally friendly engineered geomaterial for load-bearing purposes. Applying alternating current (AC) for enhancing precipitation including changing the crystalline form of the calcium carbonate precipitates appeals as a possible solution to break the upper limit of the unconfined compressive strength (UCS) of bio-treated specimens. To assess the viability of AC-assisted MICP, a series of experiments were designed and conducted under various combination of conditions. The UCS, calcium carbonate content and permeability of the bio-fabricated specimens were obtained to evaluate the treatment effectiveness of AC-assisted MICP. The results demonstrate that the UCS of the sand column exhibits a linear increase with the applied voltage from 10 V to 30 V (<em>i.e.</em>, electric field strength from 0.91 V/cm to 2.73 V/cm). The UCS value of the bio-specimen reaches 9.4 MPa after 3 treatments at a concentration of 1.00 mol/L, a voltage of 30 V, and a frequency of 100 Hz. With the assistance of an AC electric field, the adverse impacts caused by high chemical concentrations in the MICP process can be mitigated. We report that a more uniform distribution of the calcium carbonate content of the treated specimen is obtained under an optimal AC frequency of approximately 100 Hz in the current series of experiments. The induced ion vibration under the action of AC results in a change in crystalline form and an increase in the amount and uniformity of crystals precipitated on the surface of the soil grains, supported by X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images. For reference, the energy consumption and the cost for increasing the UCS of the bio-treated specimen to 5 MPa is estimated at 375.86 kWh and 676.55 HK$ per cubic meter, respectively. The findings from our experimental investigation and analysis provide compelling evidence that utilizing AC electric field holds great potential for achieving an enhanced treatment effect of MICP and hence a stronger bio-soil.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"40 ","pages":"Article 100609"},"PeriodicalIF":3.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538021","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}