Karapınar region(Konya,Türkiye)is one of the important regions of the world in terms of sinkhole formations.The research aimed to map the sinkholes in detail,to determine their spatial distribution and geometrica...Karapınar region(Konya,Türkiye)is one of the important regions of the world in terms of sinkhole formations.The research aimed to map the sinkholes in detail,to determine their spatial distribution and geometrical parameters.For this purpose,the long axes,short axes,depths and the proximity to settlements of the sinkholes were measured and their circumferences and areas were calculated.During the studies,the relationship of the sinkholes with lithology,their cross sections,shapes and the related structures were determined and the sinkholes were divided into five main groups as following:Basement rock sinkholes,Obruk Plateau sinkholes,Seyithacı sinkholes,Siyeklik sinkholes and Basin sinkholes.The d/l ratios of each sinkhole group were separately determined and interpreted.Accordingly,most of the d/l ratios are smaller than 0.2.Namely,the long axes are higher than the depth and it indicates that the shallow and wide sinkholes are common in the region.It has been determined that the fracture systems in the region,as well as the lithology and groundwater factors,are quite effective in the formation and distribution of the sinkholes in the Karapınar region.Considering the distance of the sinkholes to the settlements,Seyithac?sinkholes are the most risky group in the region because they are deep and close to the settlements.展开更多
Water level fluctuations in the reservoir deteriorate soils and rocks on the bank landslides by drying-wetting(D-W)cycles,which results in a significant decrease in mechanical properties.A comprehensive understanding ...Water level fluctuations in the reservoir deteriorate soils and rocks on the bank landslides by drying-wetting(D-W)cycles,which results in a significant decrease in mechanical properties.A comprehensive understanding of deterioration mechanism of sliding-zone soils is of great significance for interpreting the deformation behavior of landslides.However,quantitative investigation on the deterioration characteristics of soils considering the structural evolution under D-W cycles is still limited.Here,we carry out a series of laboratory tests to characterize the multi-scale deterioration of sliding-zone soils and reveal the mechanism of shear strength decay under D-W cycles.Firstly,we describe the micropores into five grades by scanning electron microscope and observe a critical change in porosity after the first three cycles.We categorize the mesoscale cracks into five classes using digital photography and observe a stepwise increase in crack area ratio.Secondly,we propose a shear strength decay model based on fractal theory which is verified by the results of consolidated undrained triaxial tests.Cohesion and friction angle of sliding-zone soils are found to show different decay patterns resulting from the staged evolution of structure.Then,structural deterioration processes including cementation destruction,pores expansion,aggregations decomposition,and clusters assembly are considered to occur to decay the shear strength differently.Finally,a three-stage deterioration mechanism associated with four structural deterioration processes is revealed,which helps to better interpret the intrinsic mechanism of shear strength decay.These findings provide the theoretical basis for the further accurate evaluation of reservoir landslides stability under water level fluctuations.展开更多
East Asian continental tectonics challenges the plate tectonics paradigm with its diffuse intraplate deformation,magmatism,and earthquakes.Despite extensive studies,fundamental questions persist.This review examines t...East Asian continental tectonics challenges the plate tectonics paradigm with its diffuse intraplate deformation,magmatism,and earthquakes.Despite extensive studies,fundamental questions persist.This review examines ten critical questions of East Asian tectonics,including the thickness of the continental lithosphere,the origin of the North–South Gravity Lineament,and the northern extent of the Indian plate beneath the Tibetan Plateau.Additional questions address the Tibetan Plateau's lateral growth,the Tianshan mountain building,the mantle flow in response to the Indo-Asian collision,and the formation of the Shanxi Rift.The review also explores the subduction along the eastern margins of the East Asian Continent and the origins of the Changbaishan volcanic field,the destruction of the North China Craton,and the development of the Mesozoic Large Granitic Province in South China.Originally presented at the DEEP2024 workshop to stimulate discussion of how SinoProbe-II research initiatives could advance our understanding of Asian tectonics,this review provides context for each question,summarizes current knowledge,and identifies promising research directions.展开更多
Leucogranite,pegmatite,and aplite from selected areas in the Wadi El Gemal area in the southern Eastern Desert of Egypt were investigated geochemically for their petrogenesis.These rocks represent a significant episod...Leucogranite,pegmatite,and aplite from selected areas in the Wadi El Gemal area in the southern Eastern Desert of Egypt were investigated geochemically for their petrogenesis.These rocks represent a significant episode of felsic magmatism during the late stage of the Pan-African orogeny in the evolution of the Arabian–Nubian Shield(ANS)during the Late Neoproterozoic.On a petrographic basis,the leucogranite is sometimes garnetiferous and can be distinguished into monzogranite,syenogranite,and alkali feldspar granite.The analyses of muscovite,biotite,garnet,and apatite reveal the magmatic nature of the studied leucogranite.The investigated leucogranite,pegmatite,and aplite are alkali-calcic,calc-alkaline,and peraluminous.The peraluminous nature of these rocks is evidenced by using the chemical analyses of biotite.These studied rocks show a slight enrichment in light rare-earth elements(LREEs)and large-ion lithophile elements(LILE,especially Rb and Th),with an insignificant depletion of heavy rareearth elements(HREEs).On a geochemical basis,the leucogranite,pegmatite,and aplite in the study area crystallized from multiple-sourced melts that include mafic,metagraywake,and pelitic.They were derived from melts generated at crystallization temperatures around 568-900℃ for leucogranite,553-781℃ for pegmatite,and 639-779℃ for aplite based on the Zr saturation geothermometers,and at a pressure around 0.39-0.48 GPa,i.e.shallow depth intrusions.The studied felsic rocks have strong negative Eu anomalies,which are very consistent with an upper crust composition,indicating fractionation of feldspar cumulates.Also,they show a moderate La/Sm ratio indicating combined magmatic processes represented by partial melting and fractional crystallization.Integration of whole-rock chemical composition and mineral microanalysis suggests that felsic magmatism in the west Wadi El Gemal area produced voluminous masses of syn-to post-collisional granite,pegmatite,and aplite.An evolutionary three-stage model is presented to understand late magmatism in the ANS in terms of a geodynamic model.Such a model discusses the propagation of felsic magmatism in the ANS during syn-collisional to post-collisional stages.展开更多
The Edikan Mine,which consists of Fobinso and Esuajah gold deposits,lies within the Asankrangwa Gold Belt of the Birimian Supergroup in the Kumasi Basin.The metasedimentary rocks in the Basins and the faulted metavolc...The Edikan Mine,which consists of Fobinso and Esuajah gold deposits,lies within the Asankrangwa Gold Belt of the Birimian Supergroup in the Kumasi Basin.The metasedimentary rocks in the Basins and the faulted metavolcanic rocks in the Belts that make up the Birimian Supergroup were intruded by granitoids during the Eburnean Orogeny.This research aims to classify granitoids in the Edikan Mine and ascertain the petrogenetic and geochemical characteristics of some auriferous granitoids in the wider Kumasi Basin,Ghana,to understand the implications for geodynamic settings.A multi-methods approach involving field studies,petrographic studies,and whole-rock geochemical analysis was used to achieve the goal of the study.Petrographic studies revealed a relatively high abundance of plagioclase and a low percentage of K-feldspars(anorthoclase and orthoclase)in the Fobinso samples,suggesting that the samples are granodioritic in nature,while the Esuajah samples showed relatively low plagioclase abundance and a high percentage in K-feldspars,indicating that they are granitic.The granitoids from the study areas are co-magmatic.The granitoids in Esuajah and Fobinso are generally enriched in large ion lithophile elements and light rare earth elements than high field strength elements,middle rare earth elements,and heavy rare earth elements,indicating mixing with crustal sources during the evolution of the granitoids.The granitoids were tectonically formed in a syn-collisional+VAG setting,which implies that they were formed in the subduction zone setting.Fobinso granodiorites showed S-type signatures with evidence of extensive crustal contamination,while the Esuajah granites showed I-type signatures with little or no crustal contamination and are peraluminous.Gold mineralization in the study area is structurally and lithologically controlled with shear zones,faulting,and veining as the principal structures controlling the mineralization.The late-stage vein,V3,in the Edikan Mine is characterized by a low vein angle and is mineralized.展开更多
With recent technological advancements,tunnel boring machines(TBM)have developed and exhibited high performance in large diameters and weak ground conditions.Tunnels are crucial structures that significantly influence...With recent technological advancements,tunnel boring machines(TBM)have developed and exhibited high performance in large diameters and weak ground conditions.Tunnels are crucial structures that significantly influence the timelines of highway and railway projects.Therefore,the construction of tunnels with TBMs becomes a preferred option.In this study,a comparative analysis between TBM and the New Austrian Tunneling Method(NATM)for tunnel construction is performed in the construction of the T1 tunnel with a diameter of 13 m,which is the longest tunnel in the E?me-Salihli section of Ankara-izmir High-Speed Railway Project(Türkiye).The selection of TBM type,measures taken in problematic sections,and application issues of TBM are discussed.The impact of correct description of geological and geotechnical conditions on both selection and performance of TBM is presented.An earth pressure balanced type TBM is chosen for the construction of the T1 tunnel.Because of the additional engineering measures taken before excavation in problematic areas,the tunnel was completed with great success within the initially planned timeframe.From this point of view,this study is an important case and may contribute to worldwide tunneling literature.展开更多
Earthquakes are predominantly associated with tectonically active regions,yet the rising frequency of seismic events globally has raised concerns about the role of industrial activities,such as fluid injection,convent...Earthquakes are predominantly associated with tectonically active regions,yet the rising frequency of seismic events globally has raised concerns about the role of industrial activities,such as fluid injection,conventional oil-gas,mining,and reservoir impoundment,in triggering significant earthquakes.While natural processes like tectonic stress changes,fluid migration,and surface loading are critical in earthquake nucleation,human-induced seismicity is becoming increasingly recognized.The Atatürk Dam,Türkiye's largest clay-core rockfill dam,situated near the East Anatolian Fault System,Adyaman Fault Zone,and Bozova Fault,offers a compelling case to explore the interplay between tectonic and anthropogenic seismicity.This study presents the first trenching studies along the Bozova Fault,revealing evidence of surface ruptures and localized seismicity linked to reservoir impoundment and conventional oil and gas.Temporal and spatial analyses suggest that reservoir-induced mechanisms,including pore pressure diffusion and stress redistribution,significantly influence seismicity,recurrence interval,alongside dominant tectonic forces.By integrating trenching investigations,seismic analyses,and stress inversion techniques,this research highlights the critical role of anthropogenic factors in modulating seismic hazards.The findings emphasize the importance of paleoseismological and geophysical studies for distinguishing induced seismicity from natural tectonic activity,thereby contributing to improved seismic hazard assessment and mitigation strategies in tectonically active,reservoir-influenced regions.展开更多
The late Carboniferous to early Permian period is renowned for extensive coal formation and frequent paleowildfires.Nonetheless,the nature and distribution of these wildfires varied significantly over time.In an effor...The late Carboniferous to early Permian period is renowned for extensive coal formation and frequent paleowildfires.Nonetheless,the nature and distribution of these wildfires varied significantly over time.In an effort to elucidate the patterns of paleowildfires during the late Paleozoic Ice Age and to probe into the controlling mechanisms of paleowildfires under icehouse conditions,a comprehensive analysis was performed on coal samples from the Taiyuan and Shanxi formations within the Dacheng coalfield of Hebei Province,North China.The dataset was augmented with global inertinite data from the late Carboniferous to early Permian periods and was compared to paleowildfire patterns from the Pliocene to Holocene epochs.The results show that paleowildfires in the Dacheng coalfield of North China transitioned from moderate-scale,low-intensity surface fires to large-scale,relatively high-intensity ground fires.Globally,the distribution of paleowildfires shifted from Euramerica to Gondwana,Cathaysia,and Angara from 300 Ma to 290 Ma,accompanied by a corresponding increase in inertinite content.This spatial and temporal variation in wildfire activity appears to have been strongly influenced by paleoclimate and atmospheric conditions.At 300 Ma,cooler and wetter paleoclimate,coupled with relatively low atmospheric pO_(2) levels,likely contributed to a reduced incidence of paleowildfires.In contrast,at 290 Ma,warmer paleoclimate,higher atmospheric pO_(2) levels,and the flourishing mires in Gondwana,Cathaysia,and Angara were conducive to more intense paleowildfires.This pattern is further supported by the comparison to more recent icehouse periods.Similar to the late Carboniferous–early Permian period,wildfire activity increased from the Pliocene to the Holocene,highlighting the critical role of climatic conditions in driving wildfire proliferation under icehouse conditions.However,the Pleistocene to Holocene wildfires were less intense than those of the late Carboniferous–early Permian,suggesting that atmospheric oxygen concentrations played a key role in modulating the evolution of the fire systems over geological timescales.These findings underscore the complex interplay between climate,atmospheric composition,and vegetation in shaping wildfire dynamics across Earth’s history.展开更多
The recent upsurge in metro construction emphasizes the necessity of understanding the mechanical performance of metro shield tunnel subjected to the influence of ground fissures.In this study,a largescale experiment,...The recent upsurge in metro construction emphasizes the necessity of understanding the mechanical performance of metro shield tunnel subjected to the influence of ground fissures.In this study,a largescale experiment,in combination with numerical simulation,was conducted to investigate the influence of ground fissures on a metro shield tunnel.The results indicate that the lining contact pressure at the vault increases in the hanging wall while decreases in the footwall,resulting in a two-dimensional stress state of vertical shear and axial tension-compression,and simultaneous vertical dislocation and axial tilt for the segments around the ground fissure.In addition,the damage to curved bolts includes tensile yield,flexural yield,and shear twist,leading to obvious concrete lining damage,particularly at the vault,arch bottom,and hance,indicating that the joints in these positions are weak areas.The shield tunnel orthogonal to the ground fissure ultimately experiences shear failure,suggesting that the maximum actual dislocation of ground fissure that the structure can withstand is approximately 20 cm,and five segment rings in the hanging wall and six segment rings in the footwall also need to be reinforced.This study could provide a reference for metro design in ground fissure sites.展开更多
The Afyon-Akşehir and Sinanpaşa grabens,located in the eastern part of the Akşehir-Simav Fault System,are important sedimentary basins in the western Anatolia,Türkiye.This region,particularly the western of Afyon...The Afyon-Akşehir and Sinanpaşa grabens,located in the eastern part of the Akşehir-Simav Fault System,are important sedimentary basins in the western Anatolia,Türkiye.This region,particularly the western of Afyon-Akşehir Graben,is a significant region known for its geothermal potential.The study focuses on analyzing gravity data to identify structural elements and examine the geological structures in the basins.The edge detection and enhancement techniques such as total horizontal gradient,tilt angle of the total horizontal gradient,enhanced dip angle and curvature analysis were used to investigate the structural lineaments in the area.Furthermore,2D/3D gravity modeling techniques were utilized to investigate the sedimentary depths of the Afyon-Akşehir and Sinanpaşa grabens.Based on the findings from the edge detection studies,three distinct linear features were highlighted in addition to previously identified geological structures.3D gravity inversion modeling reveals sedimentary basin depths of up to 470 m in Sinanpaşa Graben and 720 m in the western Afyon-Akşehir Graben.As a result of the structural mapping and 2D/3D gravity modeling studies,a structural uplift that may be linked to geothermal activity was detected among the local depressions in the Afyon-Akşehir Graben.The obtained features may be of potential interest for geothermal exploration;therefore,further investigations using additional geophysical data are recommended.展开更多
During extensive gully land consolidation projects on China's Loess Plateau,many loess-bedrock fill slopes were formed,which frequently experience shallow landslides induced by rainfall.However,studies on loess-be...During extensive gully land consolidation projects on China's Loess Plateau,many loess-bedrock fill slopes were formed,which frequently experience shallow landslides induced by rainfall.However,studies on loess-bedrock slope failure triggered by continuous heavy rainfall are limited,and the role of the soilerock interface between the original bedrock slope and fill slope in the hydrological and failure process of the slope remains unclear.In this study,we conducted a continuous rainfall model test on a loess-bedrock fill slope.During the test,the responses of volume water content,pore pressure,micro deformation,and movement of the infiltration front were observed.The hydrological process and failure mechanism were then analysed.The findings suggest that the soilerock interface is a predominant infiltration surface within the slope.Rainfall infiltration rates at the interface reach 1.24-2.80 times those of the fill slope,with peak interfacial pore water pressure exceeding that of the loess fill.Furthermore,the infiltration front moves rapidly along the interface toward the bottom of the slope,reducing interfacial cohesion between bedrock and loess.The slope failure modes are summarised into three phases:local failure→flow slide and crack penetration→multistage block retrogressive slides.The cracks generated at the slope surface serve as key determinants of the geometry and scale of shallow landslides.Therefore,we recommend targeted engineering interventions to mitigate the instability and erosion of loessebedrock fill slopes.展开更多
The traditional Green-Ampt model does not accurately represent the infiltration behavior of clay soils.Infiltration in clay is influenced by low hydraulic conductivity,strong capillary forces,and a gradual transition ...The traditional Green-Ampt model does not accurately represent the infiltration behavior of clay soils.Infiltration in clay is influenced by low hydraulic conductivity,strong capillary forces,and a gradual transition zone between saturated and unsaturated zones.These factors often lead to overestimated infiltration rates and underestimated infiltration durations.Therefore,it is necessary to improve the model to better reflect the characteristics of clay infiltration and enhance its predictive accuracy and practical applicability.This study conducts hydraulic characterization tests,one-dimensional soil column rainfall infiltration experiments,and numerical analysis on a representative clay sampled from Wuhan,China,to investigate infiltration behaviors under varying rainfall intensities and initial moisture conditions.The study reveals that the proportion of the transition layer within the wetting layer decreases with increasing wetting front depth,following a power-law function.Under the same initial moisture content,this proportion tends to converge to a stable value regardless of rainfall intensity.In contrast,under the same rainfall intensity,a higher initial moisture content leads to a larger proportion of the transition layer at a given wetting front depth.Based on the NMR curve,the unsaturated permeability coefficients corresponding to different volumetric water contents of clay can be obtained quickly,accurately,and at low cost.By utilizing the unsaturated permeability coefficient prediction model based on the nuclear magnetic resonance(NMR)curve,the study refines the computational method for the equivalent permeability coefficient in the wetting layer during clay rainfall infiltration,and proposes an improved clay Green-Ampt infiltration model that considers the saturated-unsaturated differentiation layer and the dynamic variation of its equivalent permeability coefficient under continuous rainfall conditions.The computational results of the improved model were compared with measured infiltration data,numerical simulations,and predictions from the traditional GA model.The results indicate that the improved model effectively captures the dynamic variation between the transition layer and wetting layer and provides more accurate predictions of wetting front depth in clay,with an accuracy approximately 68.36%higher than that of the traditional GA model.展开更多
Experimental research into the hydraulic conductivity curve (HCC) of unsaturated soil is limited due to the inherent challenge associated with labor, cost, and time. Typically, the HCC is estimated using the soil wate...Experimental research into the hydraulic conductivity curve (HCC) of unsaturated soil is limited due to the inherent challenge associated with labor, cost, and time. Typically, the HCC is estimated using the soil water characteristic curve (SWCC) based models and saturated hydraulic conductivity (SHC). However, the efficiency of the SWCC-based model is rarely assessed, and the influence of soil density and pore structure on HCC remains incomplete due to limited experimental data. To address this gap, this study employs an innovative filter-paper-based column method, which can measure the HCC over a wide suction range (e.g. 0−105 kPa), to capture the HCCs of both intact and compacted specimens with varying dry densities. The efficiency of two typical SWCC-based models is assessed using the measured data. Meanwhile, the mercury intrusion porosity (MIP) technique is employed to obtain the pore characteristic (i.e. pore size distribution (PSD)) and a method of predicting the HCC using the PSD data is proposed, emphasizing the dominant role of the pore structure in shaping the HCC. The results reveal that the dry density's influence on the HCC is primarily observed within the low suction range, corresponding to variations in the dominant and large pores. In the high suction range, the HCCs align along a linear trajectory when plotted in a log-log format. A notable finding is the overestimation of the HCC obtained from the SWCC-based models using the measured SHC. When the SHC is regarded as a fitting parameter, good agreement is achieved. The adjusted SHC value is typically 0-1 order of magnitude lower than the measured value, and this discrepancy diminishes as dry density increases. On the other hand, the proposed PSD-based model performs well with the measured SHC data. Caution is exercised when using the SHC to estimate the HCC for modeling water movement in partially saturated soil.展开更多
Currently,Robinia pseudoacacia L.is distributed extensively across the Chinese Loess Plateau.Root exudates released by Robinia pseudoacacia L.are one of the mechanisms through which Robinia pseudoacacia L.affects soil...Currently,Robinia pseudoacacia L.is distributed extensively across the Chinese Loess Plateau.Root exudates released by Robinia pseudoacacia L.are one of the mechanisms through which Robinia pseudoacacia L.affects soil properties.However,how root exudates influencethe hydraulic properties of soil remains unclear,especially for fine-grained soils.This knowledge gap impedes a comprehensive understanding of the function of vegetation in wastewater treatment,ecological restoration,and seepage analysis.To investigate the effect and underlying mechanisms of the root exudates of Robinia pseudoacacia L.on the saturated hydraulic conductivity of loess(a fine-grainedsoil),the saturated hydraulic conductivity,bound water content,grain size distribution,and microstructure characteristics of loess treated with root exudates at varying concentrations were determined in this study through a series of tests.The results show that the mean saturated hydraulic conductivities of the loess specimens with root exudates are all lower than those without root exudates.This phenomenon can be attributed primarily to the capacity of root exudates to directly and indirectly increase the bound water content,leading to a decrease in the effective seepage channels of the loess.For loess with/without root exudates,the variation of saturated hydraulic conductivity over time can be divided into three stages:an initial constant stage,a rapid reduction stage,and a re-stabilization stage.This is primarily attributed to the migration of particles within a specifiedsize range(7-30μm)and pore-clogging in the specimens during the seepage process.A schematic diagram is proposed for the structural evolution of fine-grained soil with or without root exudates during long-term seepage.展开更多
The Cretaceous Koum Basin is a rift-related half-graben in northern Cameroon,which constitutes a portion of the Yola Arm of the Upper Benue Trough.This study presents the first comprehensive dataset combining mineral-...The Cretaceous Koum Basin is a rift-related half-graben in northern Cameroon,which constitutes a portion of the Yola Arm of the Upper Benue Trough.This study presents the first comprehensive dataset combining mineral-ogical,bulk-rock geochemical,and stable C-H-O isotopic data for dark-gray,finegrained mudstones from the basin,providing new insights into its sediment source,paleoenvironment,and geodynamic setting.The mudstones primarily consist of phyllosilicates(~8.6%),feldspars(~30.5%),carbonates(~13.7%),and minor iron oxides(~2.7%),with vermiculite,illite,and kaolinite as the main clay minerals.The presence of analcime,ankerite,and dolomite suggests low-grade metamorphism and/or hydrothermal alteration.Fe_(2)O_(3)/K_(2)O(1.52-6.40)and SiO_(2)/Al_(2)O_(3)(2.97-4.68)ratios classify the mudstones as compositionally immature shales(ICV~1.64)with low-moderate chemical weathering(CIA~56.35;PIA~59.74;R^(3+)/R^(3+)+R^(2+)+M^(+)~0.51).Trace element ratios(Th/Sc~1.70,Zr/Sc~1.33,La/Sc~6.30,La/Th~4.14)indicate an intermediate igneous provenance from a continental crustal source.Paleoenviron-mental proxies suggest deposition in a dynamic basin environment marked by fluctuating redox(C org/P:0.21-178.34)and salinity(Sr/Ba:0.34-3.25;N-values:48-35.92)conditions,ranging from oxic to anoxic and brackish to saline.Major element data(SiO_(2) vs.Al_(2)O_(3)+K_(2)O+Na_(2)O)indicate a semi-arid regime,while Paleoclimatic indicators such as Sr/Cu(1.88-37.47)and C-values(0.12-0.93)suggests alter-nating humid and arid conditions.Notably,stable isotope data,reported here for the first time in the Koum Basin,reveal a predominantly terrestrial,fluvial-deltaic C_(3) plant source for organic carbon(δ^(13)C-25.2‰ to -35.2‰)and complex fluid-rock interactions involving meteoric and magmatic-metamorphic fluids under a warm,equatorial climate(δ^(18)O+3.6‰to +24.9‰,δ^(2)H-104‰ to-50‰).The combined mineralogical,geochemical,and isotopic data point to deposition in a tectonically active continental arc setting,with contributions from ocean island arc and passive margin sources.展开更多
Geological storage and utilization of CO_(2)involve complex interactions among Thermo-hydromechanical-chemical(THMC)coupling processes,which significantly affect storage integrity and efficiency.To address the challen...Geological storage and utilization of CO_(2)involve complex interactions among Thermo-hydromechanical-chemical(THMC)coupling processes,which significantly affect storage integrity and efficiency.To address the challenges in accurately simulating these coupled phenomena,this paper systematically reviews recent advances in the mathematical modeling and numerical solution of THMC coupling in CO_(2)geological storage.The study focuses on the derivation and structure of governing and constitutive equations,the classification and comparative performance of fully coupled,iteratively coupled,and explicitly coupled solution methods,and the modeling of dynamic changes in porosity,permeability,and fracture evolution induced by multi-field interactions.Furthermore,the paper evaluates the capabilities,application scenarios,and limitations of major simulation platforms,including TOUGH,CMG-GEM,and COMSOL.By establishing a comparative framework integrating model formulations and solver strategies,this work clarifies the strengths and gaps of current approaches and contributes to the development of robust,scalable,and mechanism-oriented numerical models for long-term prediction of CO_(2)behavior in geological formations.展开更多
This research investigates dynamic earth processes within the South Setifian allochthonous ensemble,providing insights into landscape evolution and seismotectonic activity within the Tellian mountain chain.Focusing on...This research investigates dynamic earth processes within the South Setifian allochthonous ensemble,providing insights into landscape evolution and seismotectonic activity within the Tellian mountain chain.Focusing on the Jebel Gustar and Kef Lahmar area,which includes 14 sub-basins,this research uses a DEM-based technique to assess Holocene activities,lineament characteristics,and stream systems.Five geomorphic indices are used to assess relative active tectonics:the stream lengthgradient index(SL),drainage basin asymmetry(AF),valley-floor width to valley height ratio(VF),drainage basin shape(BS),and mountain front sinuosity(SMF).A weighted overlay of these five indices produces the Index of Relative Active Tectonics(IRAT)map.The findings reveal significant neotectonic activity in the study area,supported by profound basement faulting.This research highlights the morpho-structural processes and neotectonics activity in the Jebel Gustar,providing a framework for investigating the evolution of this structure.Additionally,it enhances comprehension of the interactions between the alpine range's internal zones in Eastern Algeria and the Atlasic domain.This study proposes a systematic approach to evaluate the tectonic and geomorphological dynamics of the South Setif region.展开更多
Deposition of fluvial sandbodies is controlled mainly by characteristics of the system, such as the rate of avulsion and aggradation of the fluvial channels and their geometry. The impact and the interaction of these ...Deposition of fluvial sandbodies is controlled mainly by characteristics of the system, such as the rate of avulsion and aggradation of the fluvial channels and their geometry. The impact and the interaction of these parameters have not received adequate attention. In this paper, the impact of geological uncertainty resulting from the interpretation of the fluvial geometry, maximum depth of channels, and their avulsion rates on primary production is studied for fluvial reservoirs. Several meandering reservoirs were generated using a process-mimicking package by varying several con- trolling factors. Simulation results indicate that geometrical parameters of the fluvial channels impact cumulative pro- duction during primary production more significantly than their avulsion rate. The most significant factor appears to be the maximum depth of fluvial channels. The overall net-to-gross ratio is closely correlated with the cumulative oil production of the field, but cumulative production values for individual wells do not appear to be correlated with the local net-to-gross ratio calculated in the vicinity of each well. Connectedness of the sandbodies to each well, defined based on the minimum time-of-flight from each block to the well, appears to be a more reliable indicator of well-scale production.展开更多
This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaskanear Banska Bystrica in Slovakia.The aim of the study is to demonstrate the impossibility ...This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaskanear Banska Bystrica in Slovakia.The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material.Its maximum thickness is 3 m.Another specificific condition of the study area is its location in the built-up area,due to which the applicability of geophysical methods was limited.The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill,which complicates the identification of cave spaces.The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.展开更多
A multidisciplinary approach combining multiscale geological-structural analyses(from field to microscale) and clay mineral transformations(clay mineralogy, illite and chlorite "crystallinity" and b cell dim...A multidisciplinary approach combining multiscale geological-structural analyses(from field to microscale) and clay mineral transformations(clay mineralogy, illite and chlorite "crystallinity" and b cell dimension(b_(0)) of K-white mica) was adopted to unravel the tectono-metamorphic evolution of low-and very low-grade tectono-metamorphic units from the Intra-Pontide suture zone in northern Turkey. The mineralogical study allowed to better evaluate the structural stacking outlined during the geological mapping, leading to distinguish three tectono-metamorphic units, two in epizone(Daday and Emirkoy units) and one in anchizone(Cifter Unit) metamorphic conditions. The mesostructural and microstructural analyses suggest a polyphase tectonic-metamorphic evolution. The different macroscopic features observed between the two units characterized by the same epizone metamorphism, can be justified by the evidence that these metamorphic conditions were acquired during the last stages of exhumation in the Daday Unit, while they constrained the metamorphic-peak conditions in the Emirkoy Unit. Contemporary analyses and comparison between structural and mineralogical data have thus proven to be a powerful tool to investigate the low-grade and very low-grade metamorphic environments, allowing at the same time to solve the apparent contradictions deriving from the mineralogical study and to significantly improve the detail of the geological mapping in the field.展开更多
基金supported by the Konya Provincial Directorate of Disaster and Emergency(AFAD)within the scope of the“Detection of the Sinkhole Around Karapınar”Project(No.2020K14-138637-2)。
文摘Karapınar region(Konya,Türkiye)is one of the important regions of the world in terms of sinkhole formations.The research aimed to map the sinkholes in detail,to determine their spatial distribution and geometrical parameters.For this purpose,the long axes,short axes,depths and the proximity to settlements of the sinkholes were measured and their circumferences and areas were calculated.During the studies,the relationship of the sinkholes with lithology,their cross sections,shapes and the related structures were determined and the sinkholes were divided into five main groups as following:Basement rock sinkholes,Obruk Plateau sinkholes,Seyithacı sinkholes,Siyeklik sinkholes and Basin sinkholes.The d/l ratios of each sinkhole group were separately determined and interpreted.Accordingly,most of the d/l ratios are smaller than 0.2.Namely,the long axes are higher than the depth and it indicates that the shallow and wide sinkholes are common in the region.It has been determined that the fracture systems in the region,as well as the lithology and groundwater factors,are quite effective in the formation and distribution of the sinkholes in the Karapınar region.Considering the distance of the sinkholes to the settlements,Seyithac?sinkholes are the most risky group in the region because they are deep and close to the settlements.
基金funding support from the NSFC Key Projects of International Cooperation and Exchanges (Grant No.42020104006)the National Key Research and Development Program of China (Grant No.2023YFC3007001)the National Natural Science Foundation of China (Grant No.42307227).
文摘Water level fluctuations in the reservoir deteriorate soils and rocks on the bank landslides by drying-wetting(D-W)cycles,which results in a significant decrease in mechanical properties.A comprehensive understanding of deterioration mechanism of sliding-zone soils is of great significance for interpreting the deformation behavior of landslides.However,quantitative investigation on the deterioration characteristics of soils considering the structural evolution under D-W cycles is still limited.Here,we carry out a series of laboratory tests to characterize the multi-scale deterioration of sliding-zone soils and reveal the mechanism of shear strength decay under D-W cycles.Firstly,we describe the micropores into five grades by scanning electron microscope and observe a critical change in porosity after the first three cycles.We categorize the mesoscale cracks into five classes using digital photography and observe a stepwise increase in crack area ratio.Secondly,we propose a shear strength decay model based on fractal theory which is verified by the results of consolidated undrained triaxial tests.Cohesion and friction angle of sliding-zone soils are found to show different decay patterns resulting from the staged evolution of structure.Then,structural deterioration processes including cementation destruction,pores expansion,aggregations decomposition,and clusters assembly are considered to occur to decay the shear strength differently.Finally,a three-stage deterioration mechanism associated with four structural deterioration processes is revealed,which helps to better interpret the intrinsic mechanism of shear strength decay.These findings provide the theoretical basis for the further accurate evaluation of reservoir landslides stability under water level fluctuations.
基金supported by grants from the National Science Foundation of the USA.
文摘East Asian continental tectonics challenges the plate tectonics paradigm with its diffuse intraplate deformation,magmatism,and earthquakes.Despite extensive studies,fundamental questions persist.This review examines ten critical questions of East Asian tectonics,including the thickness of the continental lithosphere,the origin of the North–South Gravity Lineament,and the northern extent of the Indian plate beneath the Tibetan Plateau.Additional questions address the Tibetan Plateau's lateral growth,the Tianshan mountain building,the mantle flow in response to the Indo-Asian collision,and the formation of the Shanxi Rift.The review also explores the subduction along the eastern margins of the East Asian Continent and the origins of the Changbaishan volcanic field,the destruction of the North China Craton,and the development of the Mesozoic Large Granitic Province in South China.Originally presented at the DEEP2024 workshop to stimulate discussion of how SinoProbe-II research initiatives could advance our understanding of Asian tectonics,this review provides context for each question,summarizes current knowledge,and identifies promising research directions.
基金finational supported by the Foundation of Science,Technology and Innovation Funding Authority(STDF)(Award Number:47106Recipient:Mokhles K K.Azer)。
文摘Leucogranite,pegmatite,and aplite from selected areas in the Wadi El Gemal area in the southern Eastern Desert of Egypt were investigated geochemically for their petrogenesis.These rocks represent a significant episode of felsic magmatism during the late stage of the Pan-African orogeny in the evolution of the Arabian–Nubian Shield(ANS)during the Late Neoproterozoic.On a petrographic basis,the leucogranite is sometimes garnetiferous and can be distinguished into monzogranite,syenogranite,and alkali feldspar granite.The analyses of muscovite,biotite,garnet,and apatite reveal the magmatic nature of the studied leucogranite.The investigated leucogranite,pegmatite,and aplite are alkali-calcic,calc-alkaline,and peraluminous.The peraluminous nature of these rocks is evidenced by using the chemical analyses of biotite.These studied rocks show a slight enrichment in light rare-earth elements(LREEs)and large-ion lithophile elements(LILE,especially Rb and Th),with an insignificant depletion of heavy rareearth elements(HREEs).On a geochemical basis,the leucogranite,pegmatite,and aplite in the study area crystallized from multiple-sourced melts that include mafic,metagraywake,and pelitic.They were derived from melts generated at crystallization temperatures around 568-900℃ for leucogranite,553-781℃ for pegmatite,and 639-779℃ for aplite based on the Zr saturation geothermometers,and at a pressure around 0.39-0.48 GPa,i.e.shallow depth intrusions.The studied felsic rocks have strong negative Eu anomalies,which are very consistent with an upper crust composition,indicating fractionation of feldspar cumulates.Also,they show a moderate La/Sm ratio indicating combined magmatic processes represented by partial melting and fractional crystallization.Integration of whole-rock chemical composition and mineral microanalysis suggests that felsic magmatism in the west Wadi El Gemal area produced voluminous masses of syn-to post-collisional granite,pegmatite,and aplite.An evolutionary three-stage model is presented to understand late magmatism in the ANS in terms of a geodynamic model.Such a model discusses the propagation of felsic magmatism in the ANS during syn-collisional to post-collisional stages.
文摘The Edikan Mine,which consists of Fobinso and Esuajah gold deposits,lies within the Asankrangwa Gold Belt of the Birimian Supergroup in the Kumasi Basin.The metasedimentary rocks in the Basins and the faulted metavolcanic rocks in the Belts that make up the Birimian Supergroup were intruded by granitoids during the Eburnean Orogeny.This research aims to classify granitoids in the Edikan Mine and ascertain the petrogenetic and geochemical characteristics of some auriferous granitoids in the wider Kumasi Basin,Ghana,to understand the implications for geodynamic settings.A multi-methods approach involving field studies,petrographic studies,and whole-rock geochemical analysis was used to achieve the goal of the study.Petrographic studies revealed a relatively high abundance of plagioclase and a low percentage of K-feldspars(anorthoclase and orthoclase)in the Fobinso samples,suggesting that the samples are granodioritic in nature,while the Esuajah samples showed relatively low plagioclase abundance and a high percentage in K-feldspars,indicating that they are granitic.The granitoids from the study areas are co-magmatic.The granitoids in Esuajah and Fobinso are generally enriched in large ion lithophile elements and light rare earth elements than high field strength elements,middle rare earth elements,and heavy rare earth elements,indicating mixing with crustal sources during the evolution of the granitoids.The granitoids were tectonically formed in a syn-collisional+VAG setting,which implies that they were formed in the subduction zone setting.Fobinso granodiorites showed S-type signatures with evidence of extensive crustal contamination,while the Esuajah granites showed I-type signatures with little or no crustal contamination and are peraluminous.Gold mineralization in the study area is structurally and lithologically controlled with shear zones,faulting,and veining as the principal structures controlling the mineralization.The late-stage vein,V3,in the Edikan Mine is characterized by a low vein angle and is mineralized.
文摘With recent technological advancements,tunnel boring machines(TBM)have developed and exhibited high performance in large diameters and weak ground conditions.Tunnels are crucial structures that significantly influence the timelines of highway and railway projects.Therefore,the construction of tunnels with TBMs becomes a preferred option.In this study,a comparative analysis between TBM and the New Austrian Tunneling Method(NATM)for tunnel construction is performed in the construction of the T1 tunnel with a diameter of 13 m,which is the longest tunnel in the E?me-Salihli section of Ankara-izmir High-Speed Railway Project(Türkiye).The selection of TBM type,measures taken in problematic sections,and application issues of TBM are discussed.The impact of correct description of geological and geotechnical conditions on both selection and performance of TBM is presented.An earth pressure balanced type TBM is chosen for the construction of the T1 tunnel.Because of the additional engineering measures taken before excavation in problematic areas,the tunnel was completed with great success within the initially planned timeframe.From this point of view,this study is an important case and may contribute to worldwide tunneling literature.
文摘Earthquakes are predominantly associated with tectonically active regions,yet the rising frequency of seismic events globally has raised concerns about the role of industrial activities,such as fluid injection,conventional oil-gas,mining,and reservoir impoundment,in triggering significant earthquakes.While natural processes like tectonic stress changes,fluid migration,and surface loading are critical in earthquake nucleation,human-induced seismicity is becoming increasingly recognized.The Atatürk Dam,Türkiye's largest clay-core rockfill dam,situated near the East Anatolian Fault System,Adyaman Fault Zone,and Bozova Fault,offers a compelling case to explore the interplay between tectonic and anthropogenic seismicity.This study presents the first trenching studies along the Bozova Fault,revealing evidence of surface ruptures and localized seismicity linked to reservoir impoundment and conventional oil and gas.Temporal and spatial analyses suggest that reservoir-induced mechanisms,including pore pressure diffusion and stress redistribution,significantly influence seismicity,recurrence interval,alongside dominant tectonic forces.By integrating trenching investigations,seismic analyses,and stress inversion techniques,this research highlights the critical role of anthropogenic factors in modulating seismic hazards.The findings emphasize the importance of paleoseismological and geophysical studies for distinguishing induced seismicity from natural tectonic activity,thereby contributing to improved seismic hazard assessment and mitigation strategies in tectonically active,reservoir-influenced regions.
基金supported by the National Natural Science Foundation of China(Grant No.42302205 and No.42002128)the Fundamental Research Funding Project of Liaoning Education Department(Grant No.LJKMZ20220692)the Open Fund of State Key Laboratory of Coal Resources and Safe Mining(Grant No.SKLCRSM22KFA07 and No.SKLCRSM20KFA02).
文摘The late Carboniferous to early Permian period is renowned for extensive coal formation and frequent paleowildfires.Nonetheless,the nature and distribution of these wildfires varied significantly over time.In an effort to elucidate the patterns of paleowildfires during the late Paleozoic Ice Age and to probe into the controlling mechanisms of paleowildfires under icehouse conditions,a comprehensive analysis was performed on coal samples from the Taiyuan and Shanxi formations within the Dacheng coalfield of Hebei Province,North China.The dataset was augmented with global inertinite data from the late Carboniferous to early Permian periods and was compared to paleowildfire patterns from the Pliocene to Holocene epochs.The results show that paleowildfires in the Dacheng coalfield of North China transitioned from moderate-scale,low-intensity surface fires to large-scale,relatively high-intensity ground fires.Globally,the distribution of paleowildfires shifted from Euramerica to Gondwana,Cathaysia,and Angara from 300 Ma to 290 Ma,accompanied by a corresponding increase in inertinite content.This spatial and temporal variation in wildfire activity appears to have been strongly influenced by paleoclimate and atmospheric conditions.At 300 Ma,cooler and wetter paleoclimate,coupled with relatively low atmospheric pO_(2) levels,likely contributed to a reduced incidence of paleowildfires.In contrast,at 290 Ma,warmer paleoclimate,higher atmospheric pO_(2) levels,and the flourishing mires in Gondwana,Cathaysia,and Angara were conducive to more intense paleowildfires.This pattern is further supported by the comparison to more recent icehouse periods.Similar to the late Carboniferous–early Permian period,wildfire activity increased from the Pliocene to the Holocene,highlighting the critical role of climatic conditions in driving wildfire proliferation under icehouse conditions.However,the Pleistocene to Holocene wildfires were less intense than those of the late Carboniferous–early Permian,suggesting that atmospheric oxygen concentrations played a key role in modulating the evolution of the fire systems over geological timescales.These findings underscore the complex interplay between climate,atmospheric composition,and vegetation in shaping wildfire dynamics across Earth’s history.
基金supported by the National Key Research&Development Program of China(Grant No.2023YFC3008404)the Key Laboratory of Earth Fissures Geological Disaster,Ministry of Natural Resources,China(Grant Nos.EFGD20240609 and EFGD20240610).
文摘The recent upsurge in metro construction emphasizes the necessity of understanding the mechanical performance of metro shield tunnel subjected to the influence of ground fissures.In this study,a largescale experiment,in combination with numerical simulation,was conducted to investigate the influence of ground fissures on a metro shield tunnel.The results indicate that the lining contact pressure at the vault increases in the hanging wall while decreases in the footwall,resulting in a two-dimensional stress state of vertical shear and axial tension-compression,and simultaneous vertical dislocation and axial tilt for the segments around the ground fissure.In addition,the damage to curved bolts includes tensile yield,flexural yield,and shear twist,leading to obvious concrete lining damage,particularly at the vault,arch bottom,and hance,indicating that the joints in these positions are weak areas.The shield tunnel orthogonal to the ground fissure ultimately experiences shear failure,suggesting that the maximum actual dislocation of ground fissure that the structure can withstand is approximately 20 cm,and five segment rings in the hanging wall and six segment rings in the footwall also need to be reinforced.This study could provide a reference for metro design in ground fissure sites.
文摘The Afyon-Akşehir and Sinanpaşa grabens,located in the eastern part of the Akşehir-Simav Fault System,are important sedimentary basins in the western Anatolia,Türkiye.This region,particularly the western of Afyon-Akşehir Graben,is a significant region known for its geothermal potential.The study focuses on analyzing gravity data to identify structural elements and examine the geological structures in the basins.The edge detection and enhancement techniques such as total horizontal gradient,tilt angle of the total horizontal gradient,enhanced dip angle and curvature analysis were used to investigate the structural lineaments in the area.Furthermore,2D/3D gravity modeling techniques were utilized to investigate the sedimentary depths of the Afyon-Akşehir and Sinanpaşa grabens.Based on the findings from the edge detection studies,three distinct linear features were highlighted in addition to previously identified geological structures.3D gravity inversion modeling reveals sedimentary basin depths of up to 470 m in Sinanpaşa Graben and 720 m in the western Afyon-Akşehir Graben.As a result of the structural mapping and 2D/3D gravity modeling studies,a structural uplift that may be linked to geothermal activity was detected among the local depressions in the Afyon-Akşehir Graben.The obtained features may be of potential interest for geothermal exploration;therefore,further investigations using additional geophysical data are recommended.
基金supported by the National Key R&D Program of China(Grant No.2023YFC3008404)the National Key Research and Development Program,China(Grant No.2017YFD0800501)the National Natural Science Foundation of China(No.41790443).
文摘During extensive gully land consolidation projects on China's Loess Plateau,many loess-bedrock fill slopes were formed,which frequently experience shallow landslides induced by rainfall.However,studies on loess-bedrock slope failure triggered by continuous heavy rainfall are limited,and the role of the soilerock interface between the original bedrock slope and fill slope in the hydrological and failure process of the slope remains unclear.In this study,we conducted a continuous rainfall model test on a loess-bedrock fill slope.During the test,the responses of volume water content,pore pressure,micro deformation,and movement of the infiltration front were observed.The hydrological process and failure mechanism were then analysed.The findings suggest that the soilerock interface is a predominant infiltration surface within the slope.Rainfall infiltration rates at the interface reach 1.24-2.80 times those of the fill slope,with peak interfacial pore water pressure exceeding that of the loess fill.Furthermore,the infiltration front moves rapidly along the interface toward the bottom of the slope,reducing interfacial cohesion between bedrock and loess.The slope failure modes are summarised into three phases:local failure→flow slide and crack penetration→multistage block retrogressive slides.The cracks generated at the slope surface serve as key determinants of the geometry and scale of shallow landslides.Therefore,we recommend targeted engineering interventions to mitigate the instability and erosion of loessebedrock fill slopes.
基金financial support from the Joint Funds of the National Nature Science Foundation of China(No.U22A20232)Supported by Open Project Funding of Key Laboratory of Intelligent Health Perception and Ecological Restoration of Rivers and Lakes,Ministry of Education(HGKFZ07)+2 种基金the National Natural Science Foundation of China(No.51978249)Innovation Research Team Project of the Hubei Provincial Department of Science and Technology(2025AFA020)the International Collaborative Research Fund for Young Scholars in the Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes.
文摘The traditional Green-Ampt model does not accurately represent the infiltration behavior of clay soils.Infiltration in clay is influenced by low hydraulic conductivity,strong capillary forces,and a gradual transition zone between saturated and unsaturated zones.These factors often lead to overestimated infiltration rates and underestimated infiltration durations.Therefore,it is necessary to improve the model to better reflect the characteristics of clay infiltration and enhance its predictive accuracy and practical applicability.This study conducts hydraulic characterization tests,one-dimensional soil column rainfall infiltration experiments,and numerical analysis on a representative clay sampled from Wuhan,China,to investigate infiltration behaviors under varying rainfall intensities and initial moisture conditions.The study reveals that the proportion of the transition layer within the wetting layer decreases with increasing wetting front depth,following a power-law function.Under the same initial moisture content,this proportion tends to converge to a stable value regardless of rainfall intensity.In contrast,under the same rainfall intensity,a higher initial moisture content leads to a larger proportion of the transition layer at a given wetting front depth.Based on the NMR curve,the unsaturated permeability coefficients corresponding to different volumetric water contents of clay can be obtained quickly,accurately,and at low cost.By utilizing the unsaturated permeability coefficient prediction model based on the nuclear magnetic resonance(NMR)curve,the study refines the computational method for the equivalent permeability coefficient in the wetting layer during clay rainfall infiltration,and proposes an improved clay Green-Ampt infiltration model that considers the saturated-unsaturated differentiation layer and the dynamic variation of its equivalent permeability coefficient under continuous rainfall conditions.The computational results of the improved model were compared with measured infiltration data,numerical simulations,and predictions from the traditional GA model.The results indicate that the improved model effectively captures the dynamic variation between the transition layer and wetting layer and provides more accurate predictions of wetting front depth in clay,with an accuracy approximately 68.36%higher than that of the traditional GA model.
基金supported by the National Natural Science Foundation of China(Grant No.41825018)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA23090402)the National Natural Science Foundation of China(Grant No.42141009).
文摘Experimental research into the hydraulic conductivity curve (HCC) of unsaturated soil is limited due to the inherent challenge associated with labor, cost, and time. Typically, the HCC is estimated using the soil water characteristic curve (SWCC) based models and saturated hydraulic conductivity (SHC). However, the efficiency of the SWCC-based model is rarely assessed, and the influence of soil density and pore structure on HCC remains incomplete due to limited experimental data. To address this gap, this study employs an innovative filter-paper-based column method, which can measure the HCC over a wide suction range (e.g. 0−105 kPa), to capture the HCCs of both intact and compacted specimens with varying dry densities. The efficiency of two typical SWCC-based models is assessed using the measured data. Meanwhile, the mercury intrusion porosity (MIP) technique is employed to obtain the pore characteristic (i.e. pore size distribution (PSD)) and a method of predicting the HCC using the PSD data is proposed, emphasizing the dominant role of the pore structure in shaping the HCC. The results reveal that the dry density's influence on the HCC is primarily observed within the low suction range, corresponding to variations in the dominant and large pores. In the high suction range, the HCCs align along a linear trajectory when plotted in a log-log format. A notable finding is the overestimation of the HCC obtained from the SWCC-based models using the measured SHC. When the SHC is regarded as a fitting parameter, good agreement is achieved. The adjusted SHC value is typically 0-1 order of magnitude lower than the measured value, and this discrepancy diminishes as dry density increases. On the other hand, the proposed PSD-based model performs well with the measured SHC data. Caution is exercised when using the SHC to estimate the HCC for modeling water movement in partially saturated soil.
基金financial support from the National Natural Science Foundation of China(Grant Nos.42007251 and 42027806)the Doctoral Dissertation Cultivation Project of Northwest University(Grant No.YB2024016).
文摘Currently,Robinia pseudoacacia L.is distributed extensively across the Chinese Loess Plateau.Root exudates released by Robinia pseudoacacia L.are one of the mechanisms through which Robinia pseudoacacia L.affects soil properties.However,how root exudates influencethe hydraulic properties of soil remains unclear,especially for fine-grained soils.This knowledge gap impedes a comprehensive understanding of the function of vegetation in wastewater treatment,ecological restoration,and seepage analysis.To investigate the effect and underlying mechanisms of the root exudates of Robinia pseudoacacia L.on the saturated hydraulic conductivity of loess(a fine-grainedsoil),the saturated hydraulic conductivity,bound water content,grain size distribution,and microstructure characteristics of loess treated with root exudates at varying concentrations were determined in this study through a series of tests.The results show that the mean saturated hydraulic conductivities of the loess specimens with root exudates are all lower than those without root exudates.This phenomenon can be attributed primarily to the capacity of root exudates to directly and indirectly increase the bound water content,leading to a decrease in the effective seepage channels of the loess.For loess with/without root exudates,the variation of saturated hydraulic conductivity over time can be divided into three stages:an initial constant stage,a rapid reduction stage,and a re-stabilization stage.This is primarily attributed to the migration of particles within a specifiedsize range(7-30μm)and pore-clogging in the specimens during the seepage process.A schematic diagram is proposed for the structural evolution of fine-grained soil with or without root exudates during long-term seepage.
文摘The Cretaceous Koum Basin is a rift-related half-graben in northern Cameroon,which constitutes a portion of the Yola Arm of the Upper Benue Trough.This study presents the first comprehensive dataset combining mineral-ogical,bulk-rock geochemical,and stable C-H-O isotopic data for dark-gray,finegrained mudstones from the basin,providing new insights into its sediment source,paleoenvironment,and geodynamic setting.The mudstones primarily consist of phyllosilicates(~8.6%),feldspars(~30.5%),carbonates(~13.7%),and minor iron oxides(~2.7%),with vermiculite,illite,and kaolinite as the main clay minerals.The presence of analcime,ankerite,and dolomite suggests low-grade metamorphism and/or hydrothermal alteration.Fe_(2)O_(3)/K_(2)O(1.52-6.40)and SiO_(2)/Al_(2)O_(3)(2.97-4.68)ratios classify the mudstones as compositionally immature shales(ICV~1.64)with low-moderate chemical weathering(CIA~56.35;PIA~59.74;R^(3+)/R^(3+)+R^(2+)+M^(+)~0.51).Trace element ratios(Th/Sc~1.70,Zr/Sc~1.33,La/Sc~6.30,La/Th~4.14)indicate an intermediate igneous provenance from a continental crustal source.Paleoenviron-mental proxies suggest deposition in a dynamic basin environment marked by fluctuating redox(C org/P:0.21-178.34)and salinity(Sr/Ba:0.34-3.25;N-values:48-35.92)conditions,ranging from oxic to anoxic and brackish to saline.Major element data(SiO_(2) vs.Al_(2)O_(3)+K_(2)O+Na_(2)O)indicate a semi-arid regime,while Paleoclimatic indicators such as Sr/Cu(1.88-37.47)and C-values(0.12-0.93)suggests alter-nating humid and arid conditions.Notably,stable isotope data,reported here for the first time in the Koum Basin,reveal a predominantly terrestrial,fluvial-deltaic C_(3) plant source for organic carbon(δ^(13)C-25.2‰ to -35.2‰)and complex fluid-rock interactions involving meteoric and magmatic-metamorphic fluids under a warm,equatorial climate(δ^(18)O+3.6‰to +24.9‰,δ^(2)H-104‰ to-50‰).The combined mineralogical,geochemical,and isotopic data point to deposition in a tectonically active continental arc setting,with contributions from ocean island arc and passive margin sources.
基金supported by the China Postdoctoral Science Foundation(No.2024M752803)the National Natural Science Foundation of China(No.52179112)the Open Fund of National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University)(No.PLN2023-02)。
文摘Geological storage and utilization of CO_(2)involve complex interactions among Thermo-hydromechanical-chemical(THMC)coupling processes,which significantly affect storage integrity and efficiency.To address the challenges in accurately simulating these coupled phenomena,this paper systematically reviews recent advances in the mathematical modeling and numerical solution of THMC coupling in CO_(2)geological storage.The study focuses on the derivation and structure of governing and constitutive equations,the classification and comparative performance of fully coupled,iteratively coupled,and explicitly coupled solution methods,and the modeling of dynamic changes in porosity,permeability,and fracture evolution induced by multi-field interactions.Furthermore,the paper evaluates the capabilities,application scenarios,and limitations of major simulation platforms,including TOUGH,CMG-GEM,and COMSOL.By establishing a comparative framework integrating model formulations and solver strategies,this work clarifies the strengths and gaps of current approaches and contributes to the development of robust,scalable,and mechanism-oriented numerical models for long-term prediction of CO_(2)behavior in geological formations.
文摘This research investigates dynamic earth processes within the South Setifian allochthonous ensemble,providing insights into landscape evolution and seismotectonic activity within the Tellian mountain chain.Focusing on the Jebel Gustar and Kef Lahmar area,which includes 14 sub-basins,this research uses a DEM-based technique to assess Holocene activities,lineament characteristics,and stream systems.Five geomorphic indices are used to assess relative active tectonics:the stream lengthgradient index(SL),drainage basin asymmetry(AF),valley-floor width to valley height ratio(VF),drainage basin shape(BS),and mountain front sinuosity(SMF).A weighted overlay of these five indices produces the Index of Relative Active Tectonics(IRAT)map.The findings reveal significant neotectonic activity in the study area,supported by profound basement faulting.This research highlights the morpho-structural processes and neotectonics activity in the Jebel Gustar,providing a framework for investigating the evolution of this structure.Additionally,it enhances comprehension of the interactions between the alpine range's internal zones in Eastern Algeria and the Atlasic domain.This study proposes a systematic approach to evaluate the tectonic and geomorphological dynamics of the South Setif region.
文摘Deposition of fluvial sandbodies is controlled mainly by characteristics of the system, such as the rate of avulsion and aggradation of the fluvial channels and their geometry. The impact and the interaction of these parameters have not received adequate attention. In this paper, the impact of geological uncertainty resulting from the interpretation of the fluvial geometry, maximum depth of channels, and their avulsion rates on primary production is studied for fluvial reservoirs. Several meandering reservoirs were generated using a process-mimicking package by varying several con- trolling factors. Simulation results indicate that geometrical parameters of the fluvial channels impact cumulative pro- duction during primary production more significantly than their avulsion rate. The most significant factor appears to be the maximum depth of fluvial channels. The overall net-to-gross ratio is closely correlated with the cumulative oil production of the field, but cumulative production values for individual wells do not appear to be correlated with the local net-to-gross ratio calculated in the vicinity of each well. Connectedness of the sandbodies to each well, defined based on the minimum time-of-flight from each block to the well, appears to be a more reliable indicator of well-scale production.
基金the support of the project(SP2017/22)which is the base of this articlepartially supported by the Slovak Research and Development Agency under contract No.APVV-0129-12the Scientific Grant Agency of the Ministry of Education,Science,Research and Sport of the Slovak Republic and the Slovak Academy of Sciences(VEGA)within the project No.1/0559/17 and APVV 1/0462/16。
文摘This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaskanear Banska Bystrica in Slovakia.The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material.Its maximum thickness is 3 m.Another specificific condition of the study area is its location in the built-up area,due to which the applicability of geophysical methods was limited.The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill,which complicates the identification of cave spaces.The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.
基金supported by the Universitàdi Pisa (Darius, PRA 2018, PRIN 2008 and PRIN 2010-11 projects) to Michele Marronithe CNR-IGG,Pisa to Alessandro Ellero。
文摘A multidisciplinary approach combining multiscale geological-structural analyses(from field to microscale) and clay mineral transformations(clay mineralogy, illite and chlorite "crystallinity" and b cell dimension(b_(0)) of K-white mica) was adopted to unravel the tectono-metamorphic evolution of low-and very low-grade tectono-metamorphic units from the Intra-Pontide suture zone in northern Turkey. The mineralogical study allowed to better evaluate the structural stacking outlined during the geological mapping, leading to distinguish three tectono-metamorphic units, two in epizone(Daday and Emirkoy units) and one in anchizone(Cifter Unit) metamorphic conditions. The mesostructural and microstructural analyses suggest a polyphase tectonic-metamorphic evolution. The different macroscopic features observed between the two units characterized by the same epizone metamorphism, can be justified by the evidence that these metamorphic conditions were acquired during the last stages of exhumation in the Daday Unit, while they constrained the metamorphic-peak conditions in the Emirkoy Unit. Contemporary analyses and comparison between structural and mineralogical data have thus proven to be a powerful tool to investigate the low-grade and very low-grade metamorphic environments, allowing at the same time to solve the apparent contradictions deriving from the mineralogical study and to significantly improve the detail of the geological mapping in the field.
