Gas hydrates are ice-like combinations of methane and water.The global inventory of gas hydrates appears to be very large.Recent estimates of the total amount of methane contained in the world’s gas hydrates range
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
The most important aspect of every civil engineering project is acquiring reliable information on the ground on which the project will be constructed. This research includes a site investigation, which is seen as a pr...The most important aspect of every civil engineering project is acquiring reliable information on the ground on which the project will be constructed. This research includes a site investigation, which is seen as a primary stage in gathering geological, geotechnical, and other essential engineering data for structures’ safe and cost-effective design. Five boreholes at well-spaced spots were drilled for subsurface investigation at a maximum depth of 15 m to 30 m. The standard penetration tests (SPT) were performed at different depths, soil samples were taken at various intervals, and lithological changes were observed. The friction angle was between 19.6ºand 33.03º, whereas the cohesion ranges between 0.25 kg/cm<sup>2</sup> and 0.42 kg/cm<sup>2</sup>, indicating a strong resistance to shearing and a high capacity to sustain the load. Furthermore, the soil samples’ maximum dry density ranges from 1.63 g/cm<sup>3</sup> to 1.80 g/cm<sup>3</sup>. In addition, water table depths were recorded from 6.0 m to 7.0 m. The net bearing capacity for isolated/pad foundation at a depth of 1.5 m to 2.5 m below the ground level has been calculated as 95.0 to 120.0 kPa and 120.0 to 180.0 kPa for raft foundation. The net allowable pressure settlement limits for isolated/pad and raft foundations are 25 mm (1-inch) and 50 mm (2-inches), respectively. The investigation has found no severe geological flaws on the proposed construction site, and therefore it is appropriate for the construction of an Air Separation Unit (ASU) Oxygen Plant.展开更多
The objective of this paper is to demonstrate necessity to inform relevant parties about engineering-geological conditions for various practical purposes, especially including appropriate land-use planning. However, t...The objective of this paper is to demonstrate necessity to inform relevant parties about engineering-geological conditions for various practical purposes, especially including appropriate land-use planning. However, the relationship between relevant geological information and the geological environment is vital for foundation engineering purposes, especially where demanding structures are involved. This information is most conveniently structured when accumulated information concerning engineering-geological zones is utilized. This necessarily includes knowledge of rock workability and also of the pre-Quaternary bedrock, and these characteristics were then related to the current built-up area and future development according to the land-use plans in a case study are from the Petrvald Region （Czech Republic）. The geological environment of area has been severely influenced by anthropogenic effects of deep black coal mining. Results of this research showed that future development should be founded on spoil banks, dumps, and settling basins. According to the land-use plan, this zone occupies 44.9% of the area of interest, and its materials predominantly emanate from mining in the Ostrava-Karvina Coal District. For future foundation structures planned there, it is imperative to consult detailed engineering-geological study. However, attention to and reliance on this necessity is not reflected in the existing land-use plan.展开更多
In this study, the geological, petrographical properties of rhyolitic tuffs exposed around ?an-Etili in the Biga Peninsula (NW Turkey) which are pyroclastic products of Late Oligocene-Early Miocene aged ?an Volcanism ...In this study, the geological, petrographical properties of rhyolitic tuffs exposed around ?an-Etili in the Biga Peninsula (NW Turkey) which are pyroclastic products of Late Oligocene-Early Miocene aged ?an Volcanism were investigated, also physical and mechanical characteristics of tuffs introduced and tried to determine the impact on engineering properties of petrographical features. In the region, rhyolitic tuffs called locally “?an stone” have been used as covering and building stones for many years. These tuffs generally have light yellowish, beige, brown colored and different patterns with light yellowish, cream, reddish and brown colors caused by iron oxidation of hydrothermal alteration. They are preferred as coatings and decorative stone with these patterns. ?an stone which consisted of rhyolitic composition, lithic and locally crystalline tuffs has compact structure. The mineral assemblage of tuffs is mainly composed of quartz, plagioclase, rarely biotite, amphibole (hornblende) phenocrystals and opaque mineral with particles of volcanic glass and lithic fragments. Not only petrographical and geochemical analyses were carried out but also standard rock mechanic tests (unit weight, specific gravity, porosity, water absorption and uniaxial compressive strength) on rhyolitic tuffs samples collected from four different quarries (Hoppa Hill, Halilaga, Uzunalan, Dereoba). Simple regression analysis of test results obtained from four different regions and correlations were found good correlation between engineering proper- ties and the petrographical and chemical properties of rhyolitic tuffs.展开更多
Mine water pollution caused by improper discharge of industrial wastewater,waste liquid and waste residue into minedout areas is a new form of pollution occurred in China in recent years.This kind of pollution is buri...Mine water pollution caused by improper discharge of industrial wastewater,waste liquid and waste residue into minedout areas is a new form of pollution occurred in China in recent years.This kind of pollution is buried deeply,and it is difficult to control,dispose and repair.Deep contaminated mine water from abandoned mining areas may even enter the ocean,posing a great threat to marine ecosystems.In this study,using a water pollution incident occurred in a coal field at a depth of 80 m in Shandong Province,China,in 2015,as an example,the methods of engineering block disposal and groundwater remediation are reported,and the remediation effects are tested and evaluated by in-situ chemical detection and geophysical surveys.The test results showed that engineering blocking measures such as cut-off walls can obviously block the DNAPL diffusion process in mine water,but the blocking effect on organic pollutants dissolved in water was limited.It can slow down the diffusion process of organic gas.The presence of mining tunnels and mined-out areas in the contaminated zone enhances the diffusion speed of various pollutants,especially during the remediation process when pollutants rapidly spread throughout the entire contaminated area.Groundwater circulation extraction and oxidation methods have a significant degradation effect on pollutants like dichloromethane,but they may generate a large amount of secondary gaseous pollutants.These gaseous pollutants may migrate to the shallow subsurface through structures such as faults,leading to secondary subsurface contamination.When designing remediation plans,it is crucial to strike a balance between blocking and guiding in the context of both blocking and restoration projects for achieving effective remediation.展开更多
Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have di...Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have directly compared empirical methods with modelling approaches.This study investigated rockfalls in five settlements within the Cappadocia region of Türkiye,employing both empirical methods and advanced three-dimensional(3D)probabilistic modeling.The energy line angle approach was applied to identify rockfall propagation zones,while high-resolution digital surface models derived from unmanned aerial vehicle(UAV)imagery facilitated detailed 3D rockfall simulations.Cappadocia’s unique geological setting—comprising alternating layers of ignimbrites and weaker fluviolacustrine deposits—renders it highly susceptible to rockfalls intensified by wetting-drying and freeze-thaw cycles.Results indicate that rockfall propagation characteristics vary markedly between settlements:Göre and Tatlarin exhibit shorter runout distances due to basalt-dominated slopes,whereas Akköy,SoğanlıandŞahinefendi display longer trajectories associated with welded ignimbrites.Empirical cone propagation analyses correspond broadly with field observations,but variations in energy line angles(23°-33°)highlight the necessity for site-specific calibration.Comparative evaluations demonstrate that 3D probabilistic modeling better captures local-scale block dynamics and identifies high-risk areas affected by topographic and structural features such as rockfall ditches.These findings emphasize the importance of integrating empirical and 3D approaches to improve hazard zoning,optimize mitigation structures and guide the protection of Cappadocia’s unique cultural heritage landscape.展开更多
Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that empl...Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that employs machine learning algorithms as the basis for its inference rules.The system comprises four modules:a database,a repository,an inference engine,and an interpreter.A database containing 1114 rockburst cases was used to construct 357 datasets that serve as the repository for the expert system.Additionally,19 types of machine learning algorithms were used to establish 6783 micro-models to construct cognitive rules within the inference engine.By integrating probability theory and marginal analysis,a fuzzy scoring method based on the SoftMax function was developed and applied to the interpreter for rockburst intensity level prediction,effectively restoring the continuity of rockburst characteristics.The research results indicate that ensemble algorithms based on decision trees are more effective in capturing the characteristics of rockburst.Key factors for accurate prediction of rockburst intensity include uniaxial compressive strength,elastic energy index,the maximum principal stress,tangential stress,and their composite indicators.The accuracy of the proposed rockburst intensity level prediction expert system was verified using 20 engineering rockburst cases,with predictions aligning closely with the actual rockburst intensity levels.展开更多
Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong d...Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong dependence on large quantities of highquality samples,resulting in significantly low prediction accuracy of existing studies under data-scarce or crossregional prediction scenarios,which fail to meet practical application requirements.To address this issue,this study proposes an intelligent prediction model integrating transfer learning and a sampling optimization strategy,aiming to enhance the accuracy and applicability of seismic landslide susceptibility assessment.The model first improves the sample collection method through the sampling optimization strategy to enhance the precision and representativeness of training samples.This not only ensures the accuracy of origin area training but also further strengthens the model's predictive ability in the target area.Subsequently,it incorporates Transfer Component Analysis(TCA)to overcome the differences in environmental characteristics between the origin area and target area,and couples TCA with the Light GBM algorithm to construct the TCA-Light GBM model,realizing the assessment of seismic landslide susceptibility in sample-free areas.Validated through case studies of the Jiuzhaigou and Luding earthquakes,the results demonstrate that the proposed TCALight GBM transfer learning method exhibits excellent applicability in seismic landslide susceptibility prediction.After optimization with the TCA algorithm,the model's prediction performance in the target domain is significantly improved,with the AUC value increasing from 0.719 to 0.827,representing an increase of approximately 15.02%.This indicates that TCA technology can effectively alleviate the feature distribution discrepancy between the source domain and target domain,enhancing the model's generalization ability.The method is particularly suitable for scenarios with data scarcity and cross-regional prediction and can provide reliable technical support for the emergency response and risk prevention and control of seismic hazards.展开更多
Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow ...Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow River Basin.Using the‘cupball'model,this study analyzes the limiting factors and restoration characteristics across four mining areas and proposes a conceptual model for selecting appropriate restoration approaches.A second conceptual model is then introduced to address regional development needs,incorporating ecological conservation,safety protection,and people's wellbeing.The applicability of the integrated model selection framework is demonstrated through a case study on the south bank of the Qinglongjian River.The results indicate that:(1)The key limiting factors are similar across cases,but the degree of ecological degradation varies.(2)Mildly degraded areas are represented by a shallower and narrower‘cup',where natural recovery is the preferred approach,whereas moderately and severely degraded systems call for assisted regeneration and ecological reconstruction,respectively.(3)When the restoration models determined based on limiting factors and development needs are consistent,the model is directly applicable;if they differ,the option involving less artificial intervention is preferred;(4)Monitoring of the restored mining area on the Qinglongjian River's south bank confirms significant improvements in soil erosion control and vegetation coverage.This study provides a transferable methodology for balancing resource extraction with ecosystem conservation,offering practical insights for other ecologically vulnerable mining regions.展开更多
The Yuncheng Basin,located in the southern part of the Fenwei Rift,North China,exhibits obvious crust thinning(Moho uplift of 6-8 km)and shallow Curie point depth(less than 18 km)and hence holds great potential for ge...The Yuncheng Basin,located in the southern part of the Fenwei Rift,North China,exhibits obvious crust thinning(Moho uplift of 6-8 km)and shallow Curie point depth(less than 18 km)and hence holds great potential for geothermal resources.However,geothermal exploration within the Yuncheng Basin typically faces significant challenges due to civil and industrial noise from dense populations and industrial activities.To address these challenges,both Controlled-Source Audio-frequency Magnetotellurics(CSAMT)and radon measurements were employed in Baozigou village to investigate the geothermal structures and identify potential geothermal targets.The CSAMT method effectively delineated the structure of the subsurface hydrothermal system,identifying the reservoir as Paleogene sandstones and Ordovician and Cambrian limestones at elevations ranging from−800 m to−2500 m.In particular,two concealed normal faults(F_(a)and F_(b))were newly revealed by the combination of CSAMT and radon profiling;these previously undetected faults,which exhibit different scales and opposing dips,are likely to be responsible for controlling the convection of thermal water within the Basin’s subsurface hydrothermal system.Moreover,this study developed a preliminary conceptual geothermal model for the Fen River Depression within the Yuncheng Basin,which encompasses geothermal heat sources,cap rocks,reservoirs,and fluid pathways,providing valuable insights for future geothermal exploration.In conjunction with the 3D geological model constructed from CSAMT resistivity structures beneath Baozigou village,test drilling is recommended in the northwestern region of the Baozigou area to intersect the potentially deep fractured carbonates that may contain temperature-elevated geothermal water.This study establishes a good set of guidelines for future geothermal exploration in this region,indicating that high-permeability faults in the central segments of the Fen River Depression are promising targets.展开更多
Xi＇an ground fractures are the most typical ground fractures in China. Fourteen fractures have nearly divided the historical city into several distinct sections. These fractures are parallel and dis- tributed in NEE ...Xi＇an ground fractures are the most typical ground fractures in China. Fourteen fractures have nearly divided the historical city into several distinct sections. These fractures are parallel and dis- tributed in NEE direction at the same interval, with all features exhibiting a down dropping southerly block which extends to connect with the underlying fault. The activities of fractures are primarily ex- pressed as normal faults. The faulted strata are well defined and dislocation displacement increases with depth. Thus, fractures have the characteristics of syn-sedimentary faults, which constitute the hanging wall of the Lintong-Chang＇an fault branch system. Crustal thinning caused by the uplifting of upper man- tle provides a power source for extension and stretching along the fracture surface of the upper crust, which results in a series of extensional faults and the suitable conditions for forming massive ground frac- tures. The movement of tectonic blocks influences the normal dip-slipping tension of Lintong-Chang＇an fault branches, and produces a series of secondary tectonic fractures adjacent to surface, which constitute the prototype of ground fractures. The recent regional tensile stress produced by modern mainland de- formation, also profoundly influences the current activity of Xi＇an ground fractures.展开更多
Severe gas disasters in deep mining areas are increasing,and traditional protective coal seam mining is facing significant challenges.This paper proposes an innovative technology using soft rock as the protective seam...Severe gas disasters in deep mining areas are increasing,and traditional protective coal seam mining is facing significant challenges.This paper proposes an innovative technology using soft rock as the protective seam in the absence of an appropriate coal seam.Based on the geological engineering conditions of the new horizontal first mining area of Luling Coal Mine in Huaibei,China,the impacts of different mining parameters of the soft-rock protective seam on the pressure-relief effect of the protected coal seam were analyzed through numerical simulation.The unit stress of the protected coal seam,which was less than half of the primary rock stress,was used as the mining stress pressure-relief index.The optimized interlayer space was found to be 59 m for the first soft-rock working face,with a 2 m mining thickness and 105 m face length.The physicochemical characteristics of the orebody were analyzed,and a device selection framework for the soft-rock protective seam was developed.Optimal equipment for the working face was selected,including the fully-mechanized hydraulic support and coal cutter.A production technology that combined fully-mechanized and blasting-assisted soft-rock mining was developed.Engineering practices demonstrated that normal circulation operation can be achieved on the working face of the soft-rock protective seam,with an average advancement rate of 1.64 m/d.The maximum residual gas pressure and content,which were measured at the cut hole position of the protected coal seams(Nos.8 and 9),decreased to 0.35 MPa and 4.87 m^3/t,respectively.The results suggested that soft-rock protective seam mining can produce a significant gas-control effect.展开更多
The Jiang Tso ophiolite,situated in the middle segment of the Bangong-Nujiang Suture Zone,is a part of the easternmost Qieli Lake ophiolite subzone and is close to the south of Pung Lake ophiolite.The rock association...The Jiang Tso ophiolite,situated in the middle segment of the Bangong-Nujiang Suture Zone,is a part of the easternmost Qieli Lake ophiolite subzone and is close to the south of Pung Lake ophiolite.The rock association of Jiang Tso ophiolite is relatively complete and is mainly composed of metamorphic peridotite,gabbro and diabase.Comparing with N-MORB,the ophiolite is high in Mg and low in Ti,K,Na,P,and is depleted in Nb,Ta,Hf,Th and enriched in Rb,Sr and Ba.Geochemical characteristics of the Jiang Tso ophiolite indicate it is of a supra-subduction zone type formed in the spreading ridge of back arc basin.The SHRIMP U-Pb dating of zircons from the gabbro yielded a weighted average age of 188.1±4.1 Ma(MSWD=1.4),indicating the Jiang Tso ophiolite was formed in the late stage of early Jurassic.The Sr,Nd isotopic compositions show that the Tethyan mantle domain is the depleted mantle(DM),with enriched mantle domain II(EMII).They have the same Sr,Nd isotopic composition with the India Ocean MORB type.展开更多
In this study,the mechanisms of slope instabilities triggered by engineering excavations at location of a planned tunnel portal in the northwest region of Turkey were assessed,and stability of the current slopes which...In this study,the mechanisms of slope instabilities triggered by engineering excavations at location of a planned tunnel portal in the northwest region of Turkey were assessed,and stability of the current slopes which has impacts on safety of a settlement(village)and agricultural fields was investigated.In the first stage of the study,in order to identify the geological units and structural properties of the sedimentary rocks in the area,to clarify the mechanisms of instabilities and to characterize discontinuity and rock mass properties field works were conducted.In this content,geotechnical boreholes,geophysical explorations between the boreholes,line surveys to explore discontinuity properties,preparation of slope profiles using topographical techniques and sampling of rock blocks and discontinuity planes were performed.In the second stage,laboratory tests were carried out on the samples to determine the geomechnical properties of the slope forming materials and discontinuities.Then,back analyses of the instabilities were made to assess the responsible shear strength parameters of the geological units during failures by considering laboratory shear test results too.Based on the backanalyses of the failures,the strength properties of the slope debris were estimated,and it has been clarified that the residual shear strength properties are the factors controlling slip mechanism along the beddings.Following the stability analyses,it is understood that a further instability along the mass or bedding planes in the failed and redesigned area are not expected,if the current slope geometry is not changed.However,safety factor calculated for the slope in the debris is 1.1 which is well below the recommended value in the literature.The minimum safety factor for currently stable slopes which were cut at the eastern part of the failed area is 1.22 which is also less than that suggested in literature.Some remedial measures such as mini-pile or slope flattening are suggested after analyses to increase the factor of safety for this part below the settlement.展开更多
Cooling of the Earth＇s mantle since the Meso-Archean is predicted by thermal and petrological models to have induced a secular change in the composition of primary mantle-derived magmas-and thus bulk oceanic crust; i...Cooling of the Earth＇s mantle since the Meso-Archean is predicted by thermal and petrological models to have induced a secular change in the composition of primary mantle-derived magmas-and thus bulk oceanic crust; in particular, suggesting a decrease in maficity over time. This hypothesis underpins several recent studies that have addressed key geological questions concerning evolving plate tectonic styles, the rates and timing of continental crust formation, comparative planetology, and the emergence of complex life on Earth. Major, minor, and trace element geochemical analyses of（meta）mafic rocks preserved in the geological record allows exploration of this theory, although no consensus currently exists about the magnitude of this change and what compositions-if anything-constitute representative examples of Paleo-, Meso-, or Neo-Archean primitive oceanic crust. In this work, we review the current state of understanding of this issue, and use phase equilibria to examine the different mineral assemblages and rock types that would form during metamorphism of basalt of varying maficity in subduction zone environments. The presence（or absence） of such metamorphic products in the geological record is often used as evidence for（or against） the operation of modern-day subductiondriven plate tectonics on Earth at particular time periods; however, the control that secular changes in composition have on the stability of mineral assemblages diagnostic of subduction-zone metamorphism weakens such uniformitarianistic approaches. Geodynamic interpretations of the Archean metamorphic rock record must therefore employ a different set of petrological criteria for determining tectonothermal histories than those applied to Proterozoic or Phanerozoic equivalents.展开更多
Exploration of deep mineralization,particularly where the mineralization of interest is covered by a conductive overburden,is still a challenge for the conventional transient electromagnetic(TEM)method,which measures ...Exploration of deep mineralization,particularly where the mineralization of interest is covered by a conductive overburden,is still a challenge for the conventional transient electromagnetic(TEM)method,which measures TEM response using induction coils as the sensor.However,sensors such as fluxgate and superconductive quantum interfere device(SQUID)magnetometers can measure the B-field directly,which can provide more reliable deep information for mineralization exploration.In this paper,we report on the research and development of our newly developed high-temperature su-perconductor(HTS)SQUID magnetometer,which is cooled by liquid nitrogen at 77 K,and its applica-tion in TEM measurement for deep exploration in a gold deposit in China.This improved SQUID magnetometer version has a good performance with noise(60 fT/√Hz),slew rate(0.8 mT/S),dynamic range(100 dB),sensitivity(6.25 mV/nT),and bandwidth(DC-20 kHz).To find deep and peripheral ore in the Baiyun gold deposit located in Liaoning Province,NE China,both the SQUID magnetometer and induction coil were used for TEM data acquisition.Results show that TEM can detect the distribution of local strata and the faults contained within them.Results also indicate that the SQUID magnetome-ter has superior response performance for response over geological targets with slower decay time when compared to the induction coil signals.The SQUID magnetometer is more sensitive at observing the induced-polarization effect which is closely related to the ore-controlling faults.展开更多
Coal measure gas(also known as coal-bearing unconventional gas)is the key field and development direction of unconventional natural gas in recent years.The exploration and evaluation of coal measure gas(coalbed methan...Coal measure gas(also known as coal-bearing unconventional gas)is the key field and development direction of unconventional natural gas in recent years.The exploration and evaluation of coal measure gas(coalbed methane,coal shale gas and coal measure tight sandstone gas)from single coalbed methane has greatly expanded the field and space of resource evaluation,which is of positive significance for realizing the comprehensive utilization of coal resources,maximizing the benefits and promoting the innovation of oil and gas geological theory and technological advances in exploration and development.For the first time,in Yangmeishu Syncline of Western Guizhou Province,the public welfare coalbed methane geological survey project of China Geological Survey has been carried out a systematic geological survey of coal measure gas for the Upper Permian Longtan Formation,identified the geological conditions of coal measure gas and found high quality resources.The total geological resource quantity of coalbed methane and coal shale gas is 51.423×109 m3 and the geological resource abundance is up to 566×106 m3/km2.In this area,the coal measures are characterized by many layers of minable coal seams,large total thickness,thin to the medium thickness of the single layer,good gas-bearing property of coal seams and coal measure mudstone and sandstone,good reservoir physical property and high-pressure coefficient.According to the principle of combination of high quality and similarity of key parameters of the coal reservoir,the most favorable intervals are No.5-2,No.7 and No.13-2 coal seam in Well YMC1.And the pilot tests are carried out on coal seams and roof silty mudstone,such as staged perforation,increasing hydraulic fracturing scale and"three gas"production.The high and stable industrial gas flow with a daily gas output of more than 4000 m3 has been obtained,which has realized the breakthrough in the geological survey of coal measure gas in Southwest China.Based on the above investigation results,the geological characteristics of coal measure gas in the multi-thin-coal-seam-developed area and the coexploration and co-production methods,such as the optimization method of favorable intervals,the highefficiency fracturing and reservoir reconstruction method of coal measures,and the"three gas"drainage and production system,are systematically summarized in this paper.It will provide a reference for efficient exploration and development of coal measure gas in similar geological conditions in China.展开更多
Ocean mining activities have been ongoing for nearly 70 years,making great contributions to industrialization.Given the increasing demand for energy,along with the restructuring of the energy supply catalyzed by effor...Ocean mining activities have been ongoing for nearly 70 years,making great contributions to industrialization.Given the increasing demand for energy,along with the restructuring of the energy supply catalyzed by efforts to achieve a low-carbon economy,deep seabed mining will play an important role in addressing energy-and resource-related problems in the future.However,deep seabed mining remains in the exploratory stage,with many challenges presented by the high-pressure,low-temperature,and complex geologic and hydrodynamic environments in deep-sea mining areas,which are inaccessible to human activities.Thus,considerable efforts are required to ensure sustainable,economic,reliable,and safe deep seabed mining.This study reviews the latest advances in marine engineering geology and the environment related to deep-sea min-ing activities,presents a bibliometric analysis of the development of ocean mineral resources since the 1950s,summarizes the development,theory,and issues related to techniques for the three stages of ocean mining(i.e.,exploration,extraction,and closure),and discusses the engineering geology environment,geological disasters,in-situ monitoring techniques,envi-ronmental protection requirements,and environmental effects in detail.Finally,this paper gives some key conclusions and future perspectives to provide insights for subsequent studies and commercial mining operations.展开更多
Site engineering seismic survey provides basic data for seismic effect analysis. As an important parameter of soil, shear-wave velocity is usually obtained through wave velocity testing in borehole. In this paper, the...Site engineering seismic survey provides basic data for seismic effect analysis. As an important parameter of soil, shear-wave velocity is usually obtained through wave velocity testing in borehole. In this paper, the passive source surface-wave method is introduced into the site engineering seismic survey and practically applied in an engineering site of Shijingshan District. By recording the ubiquitous weak vibration on the earth surface, extract the dispersion curve from the surface-wave components using the SPAC method and obtain the shear-wave velocity structure from inversion. Over the depth of 42 m under- ground, it totally consists of five layers with interface depth of 3.31, 4.50, 7.23, 17.41, and 42.00 m; and shear-wave velocity of 144.0, 198.3, 339.4, 744.2, and 903.7 m/s, respectively. The inversion result is used to evaluate site classification, determine the maximum shear modulus of soil, provide basis for further seismic hazard analysis and site assessment or site zoning, etc. The result shows that the passive source surface-wave method is feasible in the site engineering seismic survey and can replace boreholes,shorten survey period, and reduce engineering cost to some extent.展开更多
基金funded by National Natural Science Foundation of China (41427803)
文摘Gas hydrates are ice-like combinations of methane and water.The global inventory of gas hydrates appears to be very large.Recent estimates of the total amount of methane contained in the world’s gas hydrates range
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.
文摘The most important aspect of every civil engineering project is acquiring reliable information on the ground on which the project will be constructed. This research includes a site investigation, which is seen as a primary stage in gathering geological, geotechnical, and other essential engineering data for structures’ safe and cost-effective design. Five boreholes at well-spaced spots were drilled for subsurface investigation at a maximum depth of 15 m to 30 m. The standard penetration tests (SPT) were performed at different depths, soil samples were taken at various intervals, and lithological changes were observed. The friction angle was between 19.6ºand 33.03º, whereas the cohesion ranges between 0.25 kg/cm<sup>2</sup> and 0.42 kg/cm<sup>2</sup>, indicating a strong resistance to shearing and a high capacity to sustain the load. Furthermore, the soil samples’ maximum dry density ranges from 1.63 g/cm<sup>3</sup> to 1.80 g/cm<sup>3</sup>. In addition, water table depths were recorded from 6.0 m to 7.0 m. The net bearing capacity for isolated/pad foundation at a depth of 1.5 m to 2.5 m below the ground level has been calculated as 95.0 to 120.0 kPa and 120.0 to 180.0 kPa for raft foundation. The net allowable pressure settlement limits for isolated/pad and raft foundations are 25 mm (1-inch) and 50 mm (2-inches), respectively. The investigation has found no severe geological flaws on the proposed construction site, and therefore it is appropriate for the construction of an Air Separation Unit (ASU) Oxygen Plant.
基金Czech Science Foundation for their support of project(GACR-105/09/1631)
文摘The objective of this paper is to demonstrate necessity to inform relevant parties about engineering-geological conditions for various practical purposes, especially including appropriate land-use planning. However, the relationship between relevant geological information and the geological environment is vital for foundation engineering purposes, especially where demanding structures are involved. This information is most conveniently structured when accumulated information concerning engineering-geological zones is utilized. This necessarily includes knowledge of rock workability and also of the pre-Quaternary bedrock, and these characteristics were then related to the current built-up area and future development according to the land-use plans in a case study are from the Petrvald Region （Czech Republic）. The geological environment of area has been severely influenced by anthropogenic effects of deep black coal mining. Results of this research showed that future development should be founded on spoil banks, dumps, and settling basins. According to the land-use plan, this zone occupies 44.9% of the area of interest, and its materials predominantly emanate from mining in the Ostrava-Karvina Coal District. For future foundation structures planned there, it is imperative to consult detailed engineering-geological study. However, attention to and reliance on this necessity is not reflected in the existing land-use plan.
基金financially supported by The Scientific and Technological Research Council of Turkey(TUBI-TAK.Project No.105Y114)
文摘In this study, the geological, petrographical properties of rhyolitic tuffs exposed around ?an-Etili in the Biga Peninsula (NW Turkey) which are pyroclastic products of Late Oligocene-Early Miocene aged ?an Volcanism were investigated, also physical and mechanical characteristics of tuffs introduced and tried to determine the impact on engineering properties of petrographical features. In the region, rhyolitic tuffs called locally “?an stone” have been used as covering and building stones for many years. These tuffs generally have light yellowish, beige, brown colored and different patterns with light yellowish, cream, reddish and brown colors caused by iron oxidation of hydrothermal alteration. They are preferred as coatings and decorative stone with these patterns. ?an stone which consisted of rhyolitic composition, lithic and locally crystalline tuffs has compact structure. The mineral assemblage of tuffs is mainly composed of quartz, plagioclase, rarely biotite, amphibole (hornblende) phenocrystals and opaque mineral with particles of volcanic glass and lithic fragments. Not only petrographical and geochemical analyses were carried out but also standard rock mechanic tests (unit weight, specific gravity, porosity, water absorption and uniaxial compressive strength) on rhyolitic tuffs samples collected from four different quarries (Hoppa Hill, Halilaga, Uzunalan, Dereoba). Simple regression analysis of test results obtained from four different regions and correlations were found good correlation between engineering proper- ties and the petrographical and chemical properties of rhyolitic tuffs.
基金supported by the Polluted Site Remediation Project of Gao Village,Puji Street,Zhangqiu District,Jinan City,Shandong Provincefinancially supported by the National Natural Science Foundation of China(Nos.42072331,U1906209)the Taishan Scholar Foundation(No.tstp20230626)。
文摘Mine water pollution caused by improper discharge of industrial wastewater,waste liquid and waste residue into minedout areas is a new form of pollution occurred in China in recent years.This kind of pollution is buried deeply,and it is difficult to control,dispose and repair.Deep contaminated mine water from abandoned mining areas may even enter the ocean,posing a great threat to marine ecosystems.In this study,using a water pollution incident occurred in a coal field at a depth of 80 m in Shandong Province,China,in 2015,as an example,the methods of engineering block disposal and groundwater remediation are reported,and the remediation effects are tested and evaluated by in-situ chemical detection and geophysical surveys.The test results showed that engineering blocking measures such as cut-off walls can obviously block the DNAPL diffusion process in mine water,but the blocking effect on organic pollutants dissolved in water was limited.It can slow down the diffusion process of organic gas.The presence of mining tunnels and mined-out areas in the contaminated zone enhances the diffusion speed of various pollutants,especially during the remediation process when pollutants rapidly spread throughout the entire contaminated area.Groundwater circulation extraction and oxidation methods have a significant degradation effect on pollutants like dichloromethane,but they may generate a large amount of secondary gaseous pollutants.These gaseous pollutants may migrate to the shallow subsurface through structures such as faults,leading to secondary subsurface contamination.When designing remediation plans,it is crucial to strike a balance between blocking and guiding in the context of both blocking and restoration projects for achieving effective remediation.
基金financially supported by The Scientific and Technological Research Council of Türkiye(T??B1TAK)with the project number 121C420。
文摘Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have directly compared empirical methods with modelling approaches.This study investigated rockfalls in five settlements within the Cappadocia region of Türkiye,employing both empirical methods and advanced three-dimensional(3D)probabilistic modeling.The energy line angle approach was applied to identify rockfall propagation zones,while high-resolution digital surface models derived from unmanned aerial vehicle(UAV)imagery facilitated detailed 3D rockfall simulations.Cappadocia’s unique geological setting—comprising alternating layers of ignimbrites and weaker fluviolacustrine deposits—renders it highly susceptible to rockfalls intensified by wetting-drying and freeze-thaw cycles.Results indicate that rockfall propagation characteristics vary markedly between settlements:Göre and Tatlarin exhibit shorter runout distances due to basalt-dominated slopes,whereas Akköy,SoğanlıandŞahinefendi display longer trajectories associated with welded ignimbrites.Empirical cone propagation analyses correspond broadly with field observations,but variations in energy line angles(23°-33°)highlight the necessity for site-specific calibration.Comparative evaluations demonstrate that 3D probabilistic modeling better captures local-scale block dynamics and identifies high-risk areas affected by topographic and structural features such as rockfall ditches.These findings emphasize the importance of integrating empirical and 3D approaches to improve hazard zoning,optimize mitigation structures and guide the protection of Cappadocia’s unique cultural heritage landscape.
基金Project(42077244)supported by the National Natural Science Foundation of ChinaProject(2020-05)supported by the Open Research Fund of Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization,China。
文摘Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that employs machine learning algorithms as the basis for its inference rules.The system comprises four modules:a database,a repository,an inference engine,and an interpreter.A database containing 1114 rockburst cases was used to construct 357 datasets that serve as the repository for the expert system.Additionally,19 types of machine learning algorithms were used to establish 6783 micro-models to construct cognitive rules within the inference engine.By integrating probability theory and marginal analysis,a fuzzy scoring method based on the SoftMax function was developed and applied to the interpreter for rockburst intensity level prediction,effectively restoring the continuity of rockburst characteristics.The research results indicate that ensemble algorithms based on decision trees are more effective in capturing the characteristics of rockburst.Key factors for accurate prediction of rockburst intensity include uniaxial compressive strength,elastic energy index,the maximum principal stress,tangential stress,and their composite indicators.The accuracy of the proposed rockburst intensity level prediction expert system was verified using 20 engineering rockburst cases,with predictions aligning closely with the actual rockburst intensity levels.
文摘Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong dependence on large quantities of highquality samples,resulting in significantly low prediction accuracy of existing studies under data-scarce or crossregional prediction scenarios,which fail to meet practical application requirements.To address this issue,this study proposes an intelligent prediction model integrating transfer learning and a sampling optimization strategy,aiming to enhance the accuracy and applicability of seismic landslide susceptibility assessment.The model first improves the sample collection method through the sampling optimization strategy to enhance the precision and representativeness of training samples.This not only ensures the accuracy of origin area training but also further strengthens the model's predictive ability in the target area.Subsequently,it incorporates Transfer Component Analysis(TCA)to overcome the differences in environmental characteristics between the origin area and target area,and couples TCA with the Light GBM algorithm to construct the TCA-Light GBM model,realizing the assessment of seismic landslide susceptibility in sample-free areas.Validated through case studies of the Jiuzhaigou and Luding earthquakes,the results demonstrate that the proposed TCALight GBM transfer learning method exhibits excellent applicability in seismic landslide susceptibility prediction.After optimization with the TCA algorithm,the model's prediction performance in the target domain is significantly improved,with the AUC value increasing from 0.719 to 0.827,representing an increase of approximately 15.02%.This indicates that TCA technology can effectively alleviate the feature distribution discrepancy between the source domain and target domain,enhancing the model's generalization ability.The method is particularly suitable for scenarios with data scarcity and cross-regional prediction and can provide reliable technical support for the emergency response and risk prevention and control of seismic hazards.
基金supported by Special major projects for research and development of Henan Provincial(Science and Technology Research Project)(No.252102321104)Humanities and Social Sciences Youth Foundation,Ministry of Education(24YJCZH410)。
文摘Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow River Basin.Using the‘cupball'model,this study analyzes the limiting factors and restoration characteristics across four mining areas and proposes a conceptual model for selecting appropriate restoration approaches.A second conceptual model is then introduced to address regional development needs,incorporating ecological conservation,safety protection,and people's wellbeing.The applicability of the integrated model selection framework is demonstrated through a case study on the south bank of the Qinglongjian River.The results indicate that:(1)The key limiting factors are similar across cases,but the degree of ecological degradation varies.(2)Mildly degraded areas are represented by a shallower and narrower‘cup',where natural recovery is the preferred approach,whereas moderately and severely degraded systems call for assisted regeneration and ecological reconstruction,respectively.(3)When the restoration models determined based on limiting factors and development needs are consistent,the model is directly applicable;if they differ,the option involving less artificial intervention is preferred;(4)Monitoring of the restored mining area on the Qinglongjian River's south bank confirms significant improvements in soil erosion control and vegetation coverage.This study provides a transferable methodology for balancing resource extraction with ecosystem conservation,offering practical insights for other ecologically vulnerable mining regions.
基金supported by the Shanxi Province Basic Research Program(No.20210302123374)Yuncheng University Doctoral Research Initiation Fund(No.YQ-2021008)+3 种基金Excellent doctors come to Shanxi to reward scientific research projects(No.QZX-2023020)Open Fund of State Key Laboratory of Precision Geodesy(No.SKLPG2025-1-1)Joint Open Fund of the Research Platforms of School of Computer Science,China University of Geosciences,Wuhan(No.PTLH2024-B-03)Hubei Provincial Natural Science Foundation Project(No.2025AFC095).
文摘The Yuncheng Basin,located in the southern part of the Fenwei Rift,North China,exhibits obvious crust thinning(Moho uplift of 6-8 km)and shallow Curie point depth(less than 18 km)and hence holds great potential for geothermal resources.However,geothermal exploration within the Yuncheng Basin typically faces significant challenges due to civil and industrial noise from dense populations and industrial activities.To address these challenges,both Controlled-Source Audio-frequency Magnetotellurics(CSAMT)and radon measurements were employed in Baozigou village to investigate the geothermal structures and identify potential geothermal targets.The CSAMT method effectively delineated the structure of the subsurface hydrothermal system,identifying the reservoir as Paleogene sandstones and Ordovician and Cambrian limestones at elevations ranging from−800 m to−2500 m.In particular,two concealed normal faults(F_(a)and F_(b))were newly revealed by the combination of CSAMT and radon profiling;these previously undetected faults,which exhibit different scales and opposing dips,are likely to be responsible for controlling the convection of thermal water within the Basin’s subsurface hydrothermal system.Moreover,this study developed a preliminary conceptual geothermal model for the Fen River Depression within the Yuncheng Basin,which encompasses geothermal heat sources,cap rocks,reservoirs,and fluid pathways,providing valuable insights for future geothermal exploration.In conjunction with the 3D geological model constructed from CSAMT resistivity structures beneath Baozigou village,test drilling is recommended in the northwestern region of the Baozigou area to intersect the potentially deep fractured carbonates that may contain temperature-elevated geothermal water.This study establishes a good set of guidelines for future geothermal exploration in this region,indicating that high-permeability faults in the central segments of the Fen River Depression are promising targets.
基金supported by the National Key Basic Research Project of China (No. 2014CB744703)the National Natural Science Foundation of China (Nos. 41790445, 41731066, 41674001, 41202189, 41274004, 41274005)+2 种基金the Natural Science Basic Research Plan of Shaanxi Province, China (No. 2016JM4005)the Special Fund for Basic Scientific Research of Central Universities (Nos. CHD300102268204, CHD2014G1261050, CHD2014G3263014)the China Postdoctoral Science Foundation (No. 2013M530412)
文摘Xi＇an ground fractures are the most typical ground fractures in China. Fourteen fractures have nearly divided the historical city into several distinct sections. These fractures are parallel and dis- tributed in NEE direction at the same interval, with all features exhibiting a down dropping southerly block which extends to connect with the underlying fault. The activities of fractures are primarily ex- pressed as normal faults. The faulted strata are well defined and dislocation displacement increases with depth. Thus, fractures have the characteristics of syn-sedimentary faults, which constitute the hanging wall of the Lintong-Chang＇an fault branch system. Crustal thinning caused by the uplifting of upper man- tle provides a power source for extension and stretching along the fracture surface of the upper crust, which results in a series of extensional faults and the suitable conditions for forming massive ground frac- tures. The movement of tectonic blocks influences the normal dip-slipping tension of Lintong-Chang＇an fault branches, and produces a series of secondary tectonic fractures adjacent to surface, which constitute the prototype of ground fractures. The recent regional tensile stress produced by modern mainland de- formation, also profoundly influences the current activity of Xi＇an ground fractures.
文摘Severe gas disasters in deep mining areas are increasing,and traditional protective coal seam mining is facing significant challenges.This paper proposes an innovative technology using soft rock as the protective seam in the absence of an appropriate coal seam.Based on the geological engineering conditions of the new horizontal first mining area of Luling Coal Mine in Huaibei,China,the impacts of different mining parameters of the soft-rock protective seam on the pressure-relief effect of the protected coal seam were analyzed through numerical simulation.The unit stress of the protected coal seam,which was less than half of the primary rock stress,was used as the mining stress pressure-relief index.The optimized interlayer space was found to be 59 m for the first soft-rock working face,with a 2 m mining thickness and 105 m face length.The physicochemical characteristics of the orebody were analyzed,and a device selection framework for the soft-rock protective seam was developed.Optimal equipment for the working face was selected,including the fully-mechanized hydraulic support and coal cutter.A production technology that combined fully-mechanized and blasting-assisted soft-rock mining was developed.Engineering practices demonstrated that normal circulation operation can be achieved on the working face of the soft-rock protective seam,with an average advancement rate of 1.64 m/d.The maximum residual gas pressure and content,which were measured at the cut hole position of the protected coal seams(Nos.8 and 9),decreased to 0.35 MPa and 4.87 m^3/t,respectively.The results suggested that soft-rock protective seam mining can produce a significant gas-control effect.
基金financially supported by the Tibetan special foundation of China Geological Survey(No.1212011221088 and No.1212011221087)Natural Science Foundation of China(No.41372208 and No.41472054)open foundation of State Key Laboratory of Ore Deposit Geochemistry,Chinese Academy of Sciences(No.201304)
文摘The Jiang Tso ophiolite,situated in the middle segment of the Bangong-Nujiang Suture Zone,is a part of the easternmost Qieli Lake ophiolite subzone and is close to the south of Pung Lake ophiolite.The rock association of Jiang Tso ophiolite is relatively complete and is mainly composed of metamorphic peridotite,gabbro and diabase.Comparing with N-MORB,the ophiolite is high in Mg and low in Ti,K,Na,P,and is depleted in Nb,Ta,Hf,Th and enriched in Rb,Sr and Ba.Geochemical characteristics of the Jiang Tso ophiolite indicate it is of a supra-subduction zone type formed in the spreading ridge of back arc basin.The SHRIMP U-Pb dating of zircons from the gabbro yielded a weighted average age of 188.1±4.1 Ma(MSWD=1.4),indicating the Jiang Tso ophiolite was formed in the late stage of early Jurassic.The Sr,Nd isotopic compositions show that the Tethyan mantle domain is the depleted mantle(DM),with enriched mantle domain II(EMII).They have the same Sr,Nd isotopic composition with the India Ocean MORB type.
文摘In this study,the mechanisms of slope instabilities triggered by engineering excavations at location of a planned tunnel portal in the northwest region of Turkey were assessed,and stability of the current slopes which has impacts on safety of a settlement(village)and agricultural fields was investigated.In the first stage of the study,in order to identify the geological units and structural properties of the sedimentary rocks in the area,to clarify the mechanisms of instabilities and to characterize discontinuity and rock mass properties field works were conducted.In this content,geotechnical boreholes,geophysical explorations between the boreholes,line surveys to explore discontinuity properties,preparation of slope profiles using topographical techniques and sampling of rock blocks and discontinuity planes were performed.In the second stage,laboratory tests were carried out on the samples to determine the geomechnical properties of the slope forming materials and discontinuities.Then,back analyses of the instabilities were made to assess the responsible shear strength parameters of the geological units during failures by considering laboratory shear test results too.Based on the backanalyses of the failures,the strength properties of the slope debris were estimated,and it has been clarified that the residual shear strength properties are the factors controlling slip mechanism along the beddings.Following the stability analyses,it is understood that a further instability along the mass or bedding planes in the failed and redesigned area are not expected,if the current slope geometry is not changed.However,safety factor calculated for the slope in the debris is 1.1 which is well below the recommended value in the literature.The minimum safety factor for currently stable slopes which were cut at the eastern part of the failed area is 1.22 which is also less than that suggested in literature.Some remedial measures such as mini-pile or slope flattening are suggested after analyses to increase the factor of safety for this part below the settlement.
文摘Cooling of the Earth＇s mantle since the Meso-Archean is predicted by thermal and petrological models to have induced a secular change in the composition of primary mantle-derived magmas-and thus bulk oceanic crust; in particular, suggesting a decrease in maficity over time. This hypothesis underpins several recent studies that have addressed key geological questions concerning evolving plate tectonic styles, the rates and timing of continental crust formation, comparative planetology, and the emergence of complex life on Earth. Major, minor, and trace element geochemical analyses of（meta）mafic rocks preserved in the geological record allows exploration of this theory, although no consensus currently exists about the magnitude of this change and what compositions-if anything-constitute representative examples of Paleo-, Meso-, or Neo-Archean primitive oceanic crust. In this work, we review the current state of understanding of this issue, and use phase equilibria to examine the different mineral assemblages and rock types that would form during metamorphism of basalt of varying maficity in subduction zone environments. The presence（or absence） of such metamorphic products in the geological record is often used as evidence for（or against） the operation of modern-day subductiondriven plate tectonics on Earth at particular time periods; however, the control that secular changes in composition have on the stability of mineral assemblages diagnostic of subduction-zone metamorphism weakens such uniformitarianistic approaches. Geodynamic interpretations of the Archean metamorphic rock record must therefore employ a different set of petrological criteria for determining tectonothermal histories than those applied to Proterozoic or Phanerozoic equivalents.
基金This study was supported by the National Key Research and Development Project of China(No.2018YFC0603803)Fundamental Research Funds of Chinese Academy of Geological Sciences(Nos.AS2020Y01,AS2020P01).
文摘Exploration of deep mineralization,particularly where the mineralization of interest is covered by a conductive overburden,is still a challenge for the conventional transient electromagnetic(TEM)method,which measures TEM response using induction coils as the sensor.However,sensors such as fluxgate and superconductive quantum interfere device(SQUID)magnetometers can measure the B-field directly,which can provide more reliable deep information for mineralization exploration.In this paper,we report on the research and development of our newly developed high-temperature su-perconductor(HTS)SQUID magnetometer,which is cooled by liquid nitrogen at 77 K,and its applica-tion in TEM measurement for deep exploration in a gold deposit in China.This improved SQUID magnetometer version has a good performance with noise(60 fT/√Hz),slew rate(0.8 mT/S),dynamic range(100 dB),sensitivity(6.25 mV/nT),and bandwidth(DC-20 kHz).To find deep and peripheral ore in the Baiyun gold deposit located in Liaoning Province,NE China,both the SQUID magnetometer and induction coil were used for TEM data acquisition.Results show that TEM can detect the distribution of local strata and the faults contained within them.Results also indicate that the SQUID magnetome-ter has superior response performance for response over geological targets with slower decay time when compared to the induction coil signals.The SQUID magnetometer is more sensitive at observing the induced-polarization effect which is closely related to the ore-controlling faults.
基金This study was supported by the China Geological Survey Projects(DD20160186,12120115008201)
文摘Coal measure gas(also known as coal-bearing unconventional gas)is the key field and development direction of unconventional natural gas in recent years.The exploration and evaluation of coal measure gas(coalbed methane,coal shale gas and coal measure tight sandstone gas)from single coalbed methane has greatly expanded the field and space of resource evaluation,which is of positive significance for realizing the comprehensive utilization of coal resources,maximizing the benefits and promoting the innovation of oil and gas geological theory and technological advances in exploration and development.For the first time,in Yangmeishu Syncline of Western Guizhou Province,the public welfare coalbed methane geological survey project of China Geological Survey has been carried out a systematic geological survey of coal measure gas for the Upper Permian Longtan Formation,identified the geological conditions of coal measure gas and found high quality resources.The total geological resource quantity of coalbed methane and coal shale gas is 51.423×109 m3 and the geological resource abundance is up to 566×106 m3/km2.In this area,the coal measures are characterized by many layers of minable coal seams,large total thickness,thin to the medium thickness of the single layer,good gas-bearing property of coal seams and coal measure mudstone and sandstone,good reservoir physical property and high-pressure coefficient.According to the principle of combination of high quality and similarity of key parameters of the coal reservoir,the most favorable intervals are No.5-2,No.7 and No.13-2 coal seam in Well YMC1.And the pilot tests are carried out on coal seams and roof silty mudstone,such as staged perforation,increasing hydraulic fracturing scale and"three gas"production.The high and stable industrial gas flow with a daily gas output of more than 4000 m3 has been obtained,which has realized the breakthrough in the geological survey of coal measure gas in Southwest China.Based on the above investigation results,the geological characteristics of coal measure gas in the multi-thin-coal-seam-developed area and the coexploration and co-production methods,such as the optimization method of favorable intervals,the highefficiency fracturing and reservoir reconstruction method of coal measures,and the"three gas"drainage and production system,are systematically summarized in this paper.It will provide a reference for efficient exploration and development of coal measure gas in similar geological conditions in China.
基金Funding for this research was provided by the National Natural Science Foundation of China (42022052,42277138,and 52108337)the National Key R&D Program of China (2022YFC2803800)+1 种基金the Shandong Provincial Natural Science Foundation (ZR2020YQ29)UCL's Department of Civil,Environmental and Geomatic Engineering,and Ocean University of China.
文摘Ocean mining activities have been ongoing for nearly 70 years,making great contributions to industrialization.Given the increasing demand for energy,along with the restructuring of the energy supply catalyzed by efforts to achieve a low-carbon economy,deep seabed mining will play an important role in addressing energy-and resource-related problems in the future.However,deep seabed mining remains in the exploratory stage,with many challenges presented by the high-pressure,low-temperature,and complex geologic and hydrodynamic environments in deep-sea mining areas,which are inaccessible to human activities.Thus,considerable efforts are required to ensure sustainable,economic,reliable,and safe deep seabed mining.This study reviews the latest advances in marine engineering geology and the environment related to deep-sea min-ing activities,presents a bibliometric analysis of the development of ocean mineral resources since the 1950s,summarizes the development,theory,and issues related to techniques for the three stages of ocean mining(i.e.,exploration,extraction,and closure),and discusses the engineering geology environment,geological disasters,in-situ monitoring techniques,envi-ronmental protection requirements,and environmental effects in detail.Finally,this paper gives some key conclusions and future perspectives to provide insights for subsequent studies and commercial mining operations.
基金supported by National Natural Science Foundation of China (No. 41174085)Chinese Academy of Sciences (KZZD-EW-TZ-19)China Geological Survey (12120113101400)
文摘Site engineering seismic survey provides basic data for seismic effect analysis. As an important parameter of soil, shear-wave velocity is usually obtained through wave velocity testing in borehole. In this paper, the passive source surface-wave method is introduced into the site engineering seismic survey and practically applied in an engineering site of Shijingshan District. By recording the ubiquitous weak vibration on the earth surface, extract the dispersion curve from the surface-wave components using the SPAC method and obtain the shear-wave velocity structure from inversion. Over the depth of 42 m under- ground, it totally consists of five layers with interface depth of 3.31, 4.50, 7.23, 17.41, and 42.00 m; and shear-wave velocity of 144.0, 198.3, 339.4, 744.2, and 903.7 m/s, respectively. The inversion result is used to evaluate site classification, determine the maximum shear modulus of soil, provide basis for further seismic hazard analysis and site assessment or site zoning, etc. The result shows that the passive source surface-wave method is feasible in the site engineering seismic survey and can replace boreholes,shorten survey period, and reduce engineering cost to some extent.
