Direct current resistivity and ground penetrating radar surveys were employed to obtain the value of the resistivity and dielectric constant in the brine near the Barrow, Alaska. The geophysical surveys were undertake...Direct current resistivity and ground penetrating radar surveys were employed to obtain the value of the resistivity and dielectric constant in the brine near the Barrow, Alaska. The geophysical surveys were undertaken together with the permafrost drilling program for the measuring of the ground temperature regime and for the core sampling. The sampled cores were measured for their physical and chemical properties in the laboratory under different temperature conditions ((-60) to (20) ℃). Laboratory results support field observations and led to the development of a technique for distinguishing freshwater taliks and brine layers in permafrost. These methods were also employed in freshwater taliks near Council, Alaska. The electrical resistivity is a powerful and sensitive parameter for brine detection. However, the resistivity is a less sensitive indicator of the soil type or water content under highly saline conditions. High frequency dielectric constant is an ideal second parameter for the indication of the soil type, liquid water content and other physical properties. The imaginary part of the dielectric constant and resistivity have a significant dependence upon salinity, i.e. upon freezing temperature. The ground temperature regime and the freezing point of the brine layer are important parameters for studying the electric properties of permafrost terrain.展开更多
1 Introduction Potassium is listed as one of the shortage of mineral resources in china.Geophysical and remote sensing technology plays an important role in prospecting for potash ressources.
The formation of coalesced fractures critically alters the mechanical properties of the surrounding virgin material,significantly changing the stress distribution and deformation behavior of the rock mass.However,unde...The formation of coalesced fractures critically alters the mechanical properties of the surrounding virgin material,significantly changing the stress distribution and deformation behavior of the rock mass.However,understanding the generation mechanism and accurate prediction of rock fracture growth remain challenging in many engineering projects.Despite,wide range of conventional approaches including field investigations,laboratory-scale tests,and numerical modeling,the complex geological conditions hinder their accurate determination.This study introduces a new robust and cost-effective holistic geophysical approach to determine fractures propagation and predict failure in coal-rock masses at laboratory scale applicable across scales.The proposed approach combines rock mechanics and Acoustic Emission(AE)testing systems to make useful correlation between AE source parameters and deformation kinetics.This correlation analyzes the spatiotemporal distribution of AE events to elucidate the evolution of fracture patterns in coal-rock specimens from a complex mining project.Results showed dense and complex fracturing networks within coal specimens due to higher density,compaction,and mechanical strength compared to rock samples.This is indicated by peak acoustic events at 80%–100%load versus minimal events at 0–15%load.Simulated fracture patterns closely matched observed acoustic events,identifying key lineaments(macro-cracks)representing the transition from microcracks to macro-fractures.The convergence of these lineaments indicated intensely deformed zones prone to failure,consistent with previous field investigations.Acoustic parameters describing critical damage revealed an inverse relationship between stress and AE event magnitude.At roughly 70%σmax,a dramatic fall is seen in acoustic parameters indicated the shift from small-scale to large-scale microfractures,ultimately leading to catastrophic failure of the samples.Furthermore,Single Link Cluster(SLC)analysis demonstrated strong correlation among AE events,spatial correlation length(ξ)and information entropy(H).Both increased significantly at the onset of loading and fluctuated in proximity to ultimate failure.Using the micro-crack density criterion and 3D-crack growth theory,changes in above parameters verified the cracks transformation process.These findings showed that,the proposed approach compared with the conventional approaches,can improve disaster control and management plans,predict critical failures,and save lives in global mining projects when applied to field-scale studies.展开更多
Distributed acoustic sensing(DAS)is increasingly used in seismic exploration owing to its wide frequency range,dense sampling and real-time monitoring.DAS radiation patterns help to understand angle response of DAS re...Distributed acoustic sensing(DAS)is increasingly used in seismic exploration owing to its wide frequency range,dense sampling and real-time monitoring.DAS radiation patterns help to understand angle response of DAS records and improve the quality of inversion and imaging.In this paper,we solve the 3D vertical transverse isotropic(VTI)Christoffel equation and obtain the analytical,frst-order,and zero-order Taylor expansion solutions that represent P-,SV-,and SH-wave phase velocities and polarization vectors.These analytical and approximated solutions are used to build the P/S plane-wave expression identical to the far-feld term of seismic wave,from which the strain rate expressions are derived and DAS radiation patterns are thus extracted for anisotropic P/S waves.We observe that the gauge length and phase angle terms control the radiating intensity of DAS records.Additionally,the Bond transformation is adopted to derive the DAS radiation patterns in title transverse isotropic(TTI)media,which exhibits higher complexity than that of VTI media.Several synthetic examples demonstrate the feasibility and effectiveness of our theory.展开更多
Owing to the fact that the coal-beds are with the characteristics of multi-beds, thin single-bed, rapid lateral changes and deep burial, coal-bearing source rocks are difficult to be identified and predicted, especial...Owing to the fact that the coal-beds are with the characteristics of multi-beds, thin single-bed, rapid lateral changes and deep burial, coal-bearing source rocks are difficult to be identified and predicted, especially in the lower exploration deepwater area. In this paper, a new integrative process utilizing geology and geophysics is proposed for better predicting the distribution of coal-bearing source rocks. Coal-beds were identified by the logging responses of“three higher, three lower, and one expand”and carbargilite were recognized by the characteristics of“four higher and one lower”. Based on the above logical decision, coal-beds and carbargilite can be distinguished automatically by cluster analysis of logging curves in verticality. Within the constraints of well-seismic calibration, the coal-beds group also can be detected in horizontality by the integrated representation of“negative phase, higher Q, lower impedance and lower frequency”within the seismic data. However, the distribution of coal-bearing source rocks utilizing geophysical methodology may do not conform to the geological rules of coal accumulation. And then the main geological controlling factors of coal accumulation are comprehensively analyzed as follows：（1） Paleotopography and tectonic subsidence determine the planar range of terrestrial-marine transitional facies markedly;（2） The relative sea level changes affect the accommodation space and shoreline migration, and limit the vertical range of coal-beds. More specifically, the relationship between the accommodation creation rate and the peat accumulation rate is a fundamental control on coal accumulation. The thickest and most widespread coals form where those two factors reached a state of balance;（3） The supply of autochthonous clasts and the distance between deposition places and paleovegetation accumulated area are the critical factor to form abundant coal, which means that if deposition area is close to paleouplift, there would be sufficient organic matters to form abundant source rocks. The results show that the integrated methods can significantly improve prediction accuracy of coal-bearing source rocks, which is suitable for early exploration of western deepwater area of South China Sea.展开更多
Integrated geophysical interpretation is a method of combinating different geophysics prospecting methods based on different physical properties of accumulation. As different geophysical methods own different interpre...Integrated geophysical interpretation is a method of combinating different geophysics prospecting methods based on different physical properties of accumulation. As different geophysical methods own different interpretations and varying detection accuracies, the key issue becomes how to integrate the results of several geophysical methods to corrently carry out a comprehensive explanation. Based on different geophysical results, the authors proposed an integrated geophysical explanation method and successfully applied it in practical engineering problems.展开更多
The investigated study area locates about 72 km from Jeddah City, Makkah District, Kingdom of Saudi Arabia. The study mainly aimed to define the most significant zones of possible mineralization and outline their subs...The investigated study area locates about 72 km from Jeddah City, Makkah District, Kingdom of Saudi Arabia. The study mainly aimed to define the most significant zones of possible mineralization and outline their subsurface parameters (location and strike) in the southeast of Jabal Al-Qashah. Several geophysical methods have been conducted to carry out the goal, including ground magnetic, self-potential (SP), and induced polarization (IP) methods. Integrating these methods aims to help delineate the possible mineralization in the study area. The magnetic survey was conducted along 17 profiles where these profiles were chosen to be perpendicular to the strike of the quartz shear zone. Self-potential was applied along with five profiles covering the study area. At the same time, induced polarization was used along with one profile located at the western side of the study area corresponding to some magnetic and SP profiles. The most interesting zones of mineralization were successfully determined by comparing the results of residual magnetic profile (3), SP profile (1), and IP profile, where geological structures control some mineralization.展开更多
Superconducting quantum interference device(SQUID),with the advantages of ultra⁃high sensitivity,low noise,broad frequency bandwidth,and excellent low⁃frequency response,is widely used in several geophysical methods,s...Superconducting quantum interference device(SQUID),with the advantages of ultra⁃high sensitivity,low noise,broad frequency bandwidth,and excellent low⁃frequency response,is widely used in several geophysical methods,such as vector magnetic survey,electromagnetic method,gravity and gravity gradient measurement.In this paper,the latest technological progress of SQUID and SQUID⁃based geophysical precision measurement technology are described.In addition,the advantages,characteristics,and existing problems of each measurement technology are analyzed.Combined with the requirements of current geophysical technology,the future application prospect is discussed and development suggestions are given.展开更多
Traditional geophysical prospecting methods( electromagnetic induction method,high-density resistivity method and ground penetrating radar method) were applied to the environmental quality detection of reclaimed land ...Traditional geophysical prospecting methods( electromagnetic induction method,high-density resistivity method and ground penetrating radar method) were applied to the environmental quality detection of reclaimed land in the "198" area of Shanghai. According to the results of drilling sampling and laboratory analysis,the accuracy,suitability and consistency of theses geophysical prospecting methods were evaluated.展开更多
Lithology of Triassic in southwestern Sichuan is consistent with the whole basin,and there is no discussion about stratum division,the difference is stratum denudation which is made by the uplifting of Luzhou uplift,e...Lithology of Triassic in southwestern Sichuan is consistent with the whole basin,and there is no discussion about stratum division,the difference is stratum denudation which is made by the uplifting of Luzhou uplift,especially展开更多
Engineering rock mass classification,based on empirical relations between rock mass parameters and engineering applications,is commonly used in rock engineering and forms the basis for designing rock structures.The ba...Engineering rock mass classification,based on empirical relations between rock mass parameters and engineering applications,is commonly used in rock engineering and forms the basis for designing rock structures.The basic data required may be obtained from visual observation and laboratory or field tests.However,owing to the discontinuous and variable nature of rock masses,it is difficult for rock engineers to directly obtain the specific design parameters needed.As an alternative,the use of geophysical methods in geomechanics such as seismography may largely address this problem.In this study,25 seismic profiles with the total length of 543 m have been scanned to determine the geomechanical properties of the rock mass in blocks Ⅰ,Ⅲ and Ⅳ-2 of the Choghart iron mine.Moreover,rock joint measurements and sampling for laboratory tests were conducted.The results show that the rock mass rating（RMR） and Q values have a close relation with P-wave velocity parameters,including P-wave velocity in field(V;).P-wave velocity in the laboratory(V;) and the ratio of V;V;(i.e.K;= V;/V;.However,Q value,totally,has greater correlation coefficient and less error than the RMR,In addition,rock mass parameters including rock quality designation（RQD）,uniaxial compressive strength（UCS）,joint roughness coefficient（JRC） and Schmidt number（RN） show close relationship with P-wave velocity.An equation based on these parameters was obtained to estimate the P-wave velocity in the rock mass with a correlation coefficient of 91%.The velocities in two orthogonal directions and the results of joint study show that the wave velocity anisotropy in rock mass may be used as an efficient tool to assess the strong and weak directions in rock mass.展开更多
Geophysical methods have been applied to a wide range of hydrogeological problems. With improvement in geophysical inversion algorithms and measurement tools, significant achievements have been made in the characteriz...Geophysical methods have been applied to a wide range of hydrogeological problems. With improvement in geophysical inversion algorithms and measurement tools, significant achievements have been made in the characterization of subsurface architecture, time-lapse monitoring of hydrogeological process and contaminant plumes delineation. In this paper, we summarize the geophysical methods that are most widely used in hydrogeology including Electrical Resistivity Tomography(ERT), Induced Polarization(IP), Ground Penetrating Radar(GPR) and Electromagnetic Induction(EMI). Three examples including lab and field works are used to demonstrate current application of geophysical methods for characterizing subsurface architecture and contaminant plumes. Though great progress has been made in hydrogeohysics over the last few decades at home and abroad, challenges still remain in practical applications. More recently, hydrogeophysics continues to develop in the areas of establishment of hydrogeophysical models, large-scale architecture characterization, uncertainty analysis, biogeochemical process monitoring and ecosystem science.展开更多
Electrical resistivity tomography data were acquired in proximity to the coal combustion residual landfill in an effort to image and analyze seepage pathways through the shallow residual soil and underlying karsted li...Electrical resistivity tomography data were acquired in proximity to the coal combustion residual landfill in an effort to image and analyze seepage pathways through the shallow residual soil and underlying karsted limestone bedrock. The water table is at a depth of more than 45 m. The most prominent subsurface seepage pathways identified on the acquired electrical resistivity tomography data are located immediately adjacent to the toe of the landfill and are attributed to stormwater run-off. The moisture content of the limestone appears to decrease gradually with increasing distance from the toe of the landfill, suggesting there is also a horizontal component of moisture flow in the subsurface. Shallow limestone with higher moisture content generally underlies or is in close proximity to anthropogenic features such as drainage ditches and clay berms that are designed to channel run-off. At one location, electrical resistivity tomography data were acquired along essentially the same traverse at different times of the year, and the resistivity of shallow limestone overall was lower on the data acquired after heavy rains.展开更多
North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment（GRACE） gravity data from 2009 to 2013 are used to calculate the gravity change r...North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment（GRACE） gravity data from 2009 to 2013 are used to calculate the gravity change rate（GCR） using the polynomial fitting method. In general, the study area was divided into the Shanxi rift, Jing-Jin-Ji（Beijing-Tianjin-Hebei Province）, and Bohai Bay Basin（BBB） regions. Results of the distribution of the GCR determined from ground-based gravimetry show that the GCR appears to be ＂negativepositive-negative＂ from west to east, which indicates that different geophysical mechanisms are involved in the tectonic activities of these regions. However, GRACE solutions are conducted over a larger spatial scale and are able to show a difference between southern and northern areas and a mass redistribution of land water storage.展开更多
Rising sea levels and climate change are reshaping coastal landscapes,exacerbating erosion,and increasing flood frequency,posing serious threats to the ecological balance,economic growth,and the livelihoods of coastal...Rising sea levels and climate change are reshaping coastal landscapes,exacerbating erosion,and increasing flood frequency,posing serious threats to the ecological balance,economic growth,and the livelihoods of coastal city residents[1].This necessitates advanced monitoring to mitigate climate impacts and strengthen coastal resilience.While geophysical methods for first-order coastal properties monitoring have gained traction in academia[2,3],traditional monitoring techniques are limited by sparse and unevenly distributed observation stations,failing to meet the needs for detailed regional monitoring.Moreover,the complex social and cultural environments of coastal cities challenge sustained and intensive monitoring efforts.展开更多
Microbial electrochemical technologies(MET)can remove a variety of organic and inorganic pollutants from contaminated groundwater.However,despite significant laboratory-scale successes over the past decade,field-scale...Microbial electrochemical technologies(MET)can remove a variety of organic and inorganic pollutants from contaminated groundwater.However,despite significant laboratory-scale successes over the past decade,field-scale applications remain limited.We hypothesize that enhancing the electrochemical conductivity of the soil surrounding electrodes could be a groundbreaking and cost-effective alternative to deploying numerous high-surface-area electrodes in short distances.This could be achieved by injecting environmentally safe iron-or carbon-based conductive(nano)particles into the aquifer.Upon transport and deposition onto soil grains,these particles create an electrically conductive zone that can be exploited to control and fine-tune the delivery of electron donors or acceptors over large distances,thereby driving the process more efficiently.Beyond extending the radius of influence of electrodes,these diffuse electro-conductive zones(DECZ)could also promote the development of syntrophic anaerobic communities that degrade contaminants via direct interspecies electron transfer(DIET).In this review,we present the state-of-the-art in applying conductive materials for MET and DIET-based applications.We also provide a comprehensive overview of the physicochemical properties of candidate electrochemically conductive materials and related injection strategies suitable for field-scale implementation.Finally,we illustrate and critically discuss current and prospective electrochemical and geophysical methods for measuring soil electronic conductivitydboth in the laboratory and in the fielddbefore and after injection practices,which are crucial for determining the extent of DECZ.This review article provides critical information for a robust design and in situ implementation of groundwater electro-bioremediation processes.展开更多
文摘Direct current resistivity and ground penetrating radar surveys were employed to obtain the value of the resistivity and dielectric constant in the brine near the Barrow, Alaska. The geophysical surveys were undertaken together with the permafrost drilling program for the measuring of the ground temperature regime and for the core sampling. The sampled cores were measured for their physical and chemical properties in the laboratory under different temperature conditions ((-60) to (20) ℃). Laboratory results support field observations and led to the development of a technique for distinguishing freshwater taliks and brine layers in permafrost. These methods were also employed in freshwater taliks near Council, Alaska. The electrical resistivity is a powerful and sensitive parameter for brine detection. However, the resistivity is a less sensitive indicator of the soil type or water content under highly saline conditions. High frequency dielectric constant is an ideal second parameter for the indication of the soil type, liquid water content and other physical properties. The imaginary part of the dielectric constant and resistivity have a significant dependence upon salinity, i.e. upon freezing temperature. The ground temperature regime and the freezing point of the brine layer are important parameters for studying the electric properties of permafrost terrain.
基金financially supported by projects of 2006AA06A208, 2013AA0639, 1212011120188 and 12120113099000
文摘1 Introduction Potassium is listed as one of the shortage of mineral resources in china.Geophysical and remote sensing technology plays an important role in prospecting for potash ressources.
基金supported by Beijing Natural Science Foundation(International Scientists Project,Grant No.IS23116)Research Fund for International Young Scientists(RFISI)of National Science Foundation of China(42250410327).
文摘The formation of coalesced fractures critically alters the mechanical properties of the surrounding virgin material,significantly changing the stress distribution and deformation behavior of the rock mass.However,understanding the generation mechanism and accurate prediction of rock fracture growth remain challenging in many engineering projects.Despite,wide range of conventional approaches including field investigations,laboratory-scale tests,and numerical modeling,the complex geological conditions hinder their accurate determination.This study introduces a new robust and cost-effective holistic geophysical approach to determine fractures propagation and predict failure in coal-rock masses at laboratory scale applicable across scales.The proposed approach combines rock mechanics and Acoustic Emission(AE)testing systems to make useful correlation between AE source parameters and deformation kinetics.This correlation analyzes the spatiotemporal distribution of AE events to elucidate the evolution of fracture patterns in coal-rock specimens from a complex mining project.Results showed dense and complex fracturing networks within coal specimens due to higher density,compaction,and mechanical strength compared to rock samples.This is indicated by peak acoustic events at 80%–100%load versus minimal events at 0–15%load.Simulated fracture patterns closely matched observed acoustic events,identifying key lineaments(macro-cracks)representing the transition from microcracks to macro-fractures.The convergence of these lineaments indicated intensely deformed zones prone to failure,consistent with previous field investigations.Acoustic parameters describing critical damage revealed an inverse relationship between stress and AE event magnitude.At roughly 70%σmax,a dramatic fall is seen in acoustic parameters indicated the shift from small-scale to large-scale microfractures,ultimately leading to catastrophic failure of the samples.Furthermore,Single Link Cluster(SLC)analysis demonstrated strong correlation among AE events,spatial correlation length(ξ)and information entropy(H).Both increased significantly at the onset of loading and fluctuated in proximity to ultimate failure.Using the micro-crack density criterion and 3D-crack growth theory,changes in above parameters verified the cracks transformation process.These findings showed that,the proposed approach compared with the conventional approaches,can improve disaster control and management plans,predict critical failures,and save lives in global mining projects when applied to field-scale studies.
基金supported by the National Key R&D Program of China under grant No.2021YFA0716800。
文摘Distributed acoustic sensing(DAS)is increasingly used in seismic exploration owing to its wide frequency range,dense sampling and real-time monitoring.DAS radiation patterns help to understand angle response of DAS records and improve the quality of inversion and imaging.In this paper,we solve the 3D vertical transverse isotropic(VTI)Christoffel equation and obtain the analytical,frst-order,and zero-order Taylor expansion solutions that represent P-,SV-,and SH-wave phase velocities and polarization vectors.These analytical and approximated solutions are used to build the P/S plane-wave expression identical to the far-feld term of seismic wave,from which the strain rate expressions are derived and DAS radiation patterns are thus extracted for anisotropic P/S waves.We observe that the gauge length and phase angle terms control the radiating intensity of DAS records.Additionally,the Bond transformation is adopted to derive the DAS radiation patterns in title transverse isotropic(TTI)media,which exhibits higher complexity than that of VTI media.Several synthetic examples demonstrate the feasibility and effectiveness of our theory.
基金The Major National Science and Technology Programs in the "Twelfth Five-Year" Plan period under contract No.2011ZX05025-002-02-02the National Natural Science Foundation of China under contract Nos 41472084,41202074 and 41172123the foundation of Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences) of Ministry of Education under contract No.TPR-2013-13
文摘Owing to the fact that the coal-beds are with the characteristics of multi-beds, thin single-bed, rapid lateral changes and deep burial, coal-bearing source rocks are difficult to be identified and predicted, especially in the lower exploration deepwater area. In this paper, a new integrative process utilizing geology and geophysics is proposed for better predicting the distribution of coal-bearing source rocks. Coal-beds were identified by the logging responses of“three higher, three lower, and one expand”and carbargilite were recognized by the characteristics of“four higher and one lower”. Based on the above logical decision, coal-beds and carbargilite can be distinguished automatically by cluster analysis of logging curves in verticality. Within the constraints of well-seismic calibration, the coal-beds group also can be detected in horizontality by the integrated representation of“negative phase, higher Q, lower impedance and lower frequency”within the seismic data. However, the distribution of coal-bearing source rocks utilizing geophysical methodology may do not conform to the geological rules of coal accumulation. And then the main geological controlling factors of coal accumulation are comprehensively analyzed as follows：（1） Paleotopography and tectonic subsidence determine the planar range of terrestrial-marine transitional facies markedly;（2） The relative sea level changes affect the accommodation space and shoreline migration, and limit the vertical range of coal-beds. More specifically, the relationship between the accommodation creation rate and the peat accumulation rate is a fundamental control on coal accumulation. The thickest and most widespread coals form where those two factors reached a state of balance;（3） The supply of autochthonous clasts and the distance between deposition places and paleovegetation accumulated area are the critical factor to form abundant coal, which means that if deposition area is close to paleouplift, there would be sufficient organic matters to form abundant source rocks. The results show that the integrated methods can significantly improve prediction accuracy of coal-bearing source rocks, which is suitable for early exploration of western deepwater area of South China Sea.
基金Project of Research on Integrated Geophysical Interpretation on Accumulation (No. CHC-KJ-2004-11)
文摘Integrated geophysical interpretation is a method of combinating different geophysics prospecting methods based on different physical properties of accumulation. As different geophysical methods own different interpretations and varying detection accuracies, the key issue becomes how to integrate the results of several geophysical methods to corrently carry out a comprehensive explanation. Based on different geophysical results, the authors proposed an integrated geophysical explanation method and successfully applied it in practical engineering problems.
文摘The investigated study area locates about 72 km from Jeddah City, Makkah District, Kingdom of Saudi Arabia. The study mainly aimed to define the most significant zones of possible mineralization and outline their subsurface parameters (location and strike) in the southeast of Jabal Al-Qashah. Several geophysical methods have been conducted to carry out the goal, including ground magnetic, self-potential (SP), and induced polarization (IP) methods. Integrating these methods aims to help delineate the possible mineralization in the study area. The magnetic survey was conducted along 17 profiles where these profiles were chosen to be perpendicular to the strike of the quartz shear zone. Self-potential was applied along with five profiles covering the study area. At the same time, induced polarization was used along with one profile located at the western side of the study area corresponding to some magnetic and SP profiles. The most interesting zones of mineralization were successfully determined by comparing the results of residual magnetic profile (3), SP profile (1), and IP profile, where geological structures control some mineralization.
基金National Natural Science Foundation of China(Grant No.41704172)the National Key Research and Development Project(Grant No.2017YFC0602000)the National Key Research and Development Project(Grant No.2016YFC0303000).
文摘Superconducting quantum interference device(SQUID),with the advantages of ultra⁃high sensitivity,low noise,broad frequency bandwidth,and excellent low⁃frequency response,is widely used in several geophysical methods,such as vector magnetic survey,electromagnetic method,gravity and gravity gradient measurement.In this paper,the latest technological progress of SQUID and SQUID⁃based geophysical precision measurement technology are described.In addition,the advantages,characteristics,and existing problems of each measurement technology are analyzed.Combined with the requirements of current geophysical technology,the future application prospect is discussed and development suggestions are given.
文摘Traditional geophysical prospecting methods( electromagnetic induction method,high-density resistivity method and ground penetrating radar method) were applied to the environmental quality detection of reclaimed land in the "198" area of Shanghai. According to the results of drilling sampling and laboratory analysis,the accuracy,suitability and consistency of theses geophysical prospecting methods were evaluated.
文摘Lithology of Triassic in southwestern Sichuan is consistent with the whole basin,and there is no discussion about stratum division,the difference is stratum denudation which is made by the uplifting of Luzhou uplift,especially
文摘Engineering rock mass classification,based on empirical relations between rock mass parameters and engineering applications,is commonly used in rock engineering and forms the basis for designing rock structures.The basic data required may be obtained from visual observation and laboratory or field tests.However,owing to the discontinuous and variable nature of rock masses,it is difficult for rock engineers to directly obtain the specific design parameters needed.As an alternative,the use of geophysical methods in geomechanics such as seismography may largely address this problem.In this study,25 seismic profiles with the total length of 543 m have been scanned to determine the geomechanical properties of the rock mass in blocks Ⅰ,Ⅲ and Ⅳ-2 of the Choghart iron mine.Moreover,rock joint measurements and sampling for laboratory tests were conducted.The results show that the rock mass rating（RMR） and Q values have a close relation with P-wave velocity parameters,including P-wave velocity in field(V;).P-wave velocity in the laboratory(V;) and the ratio of V;V;(i.e.K;= V;/V;.However,Q value,totally,has greater correlation coefficient and less error than the RMR,In addition,rock mass parameters including rock quality designation（RQD）,uniaxial compressive strength（UCS）,joint roughness coefficient（JRC） and Schmidt number（RN） show close relationship with P-wave velocity.An equation based on these parameters was obtained to estimate the P-wave velocity in the rock mass with a correlation coefficient of 91%.The velocities in two orthogonal directions and the results of joint study show that the wave velocity anisotropy in rock mass may be used as an efficient tool to assess the strong and weak directions in rock mass.
基金funded by the National Natural Science Fund of China (NSFC)-Xinjiang No.U1503282the NSFC No.41030746,41672229 and 41172206
文摘Geophysical methods have been applied to a wide range of hydrogeological problems. With improvement in geophysical inversion algorithms and measurement tools, significant achievements have been made in the characterization of subsurface architecture, time-lapse monitoring of hydrogeological process and contaminant plumes delineation. In this paper, we summarize the geophysical methods that are most widely used in hydrogeology including Electrical Resistivity Tomography(ERT), Induced Polarization(IP), Ground Penetrating Radar(GPR) and Electromagnetic Induction(EMI). Three examples including lab and field works are used to demonstrate current application of geophysical methods for characterizing subsurface architecture and contaminant plumes. Though great progress has been made in hydrogeohysics over the last few decades at home and abroad, challenges still remain in practical applications. More recently, hydrogeophysics continues to develop in the areas of establishment of hydrogeophysical models, large-scale architecture characterization, uncertainty analysis, biogeochemical process monitoring and ecosystem science.
文摘Electrical resistivity tomography data were acquired in proximity to the coal combustion residual landfill in an effort to image and analyze seepage pathways through the shallow residual soil and underlying karsted limestone bedrock. The water table is at a depth of more than 45 m. The most prominent subsurface seepage pathways identified on the acquired electrical resistivity tomography data are located immediately adjacent to the toe of the landfill and are attributed to stormwater run-off. The moisture content of the limestone appears to decrease gradually with increasing distance from the toe of the landfill, suggesting there is also a horizontal component of moisture flow in the subsurface. Shallow limestone with higher moisture content generally underlies or is in close proximity to anthropogenic features such as drainage ditches and clay berms that are designed to channel run-off. At one location, electrical resistivity tomography data were acquired along essentially the same traverse at different times of the year, and the resistivity of shallow limestone overall was lower on the data acquired after heavy rains.
基金supported by the National Natural Science Foundation of China(41304060)the national key basic research and development plan(2013CB733304)
文摘North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment（GRACE） gravity data from 2009 to 2013 are used to calculate the gravity change rate（GCR） using the polynomial fitting method. In general, the study area was divided into the Shanxi rift, Jing-Jin-Ji（Beijing-Tianjin-Hebei Province）, and Bohai Bay Basin（BBB） regions. Results of the distribution of the GCR determined from ground-based gravimetry show that the GCR appears to be ＂negativepositive-negative＂ from west to east, which indicates that different geophysical mechanisms are involved in the tectonic activities of these regions. However, GRACE solutions are conducted over a larger spatial scale and are able to show a difference between southern and northern areas and a mass redistribution of land water storage.
基金supported by scientific grants from Zhejiang University(2023QZJH07)。
文摘Rising sea levels and climate change are reshaping coastal landscapes,exacerbating erosion,and increasing flood frequency,posing serious threats to the ecological balance,economic growth,and the livelihoods of coastal city residents[1].This necessitates advanced monitoring to mitigate climate impacts and strengthen coastal resilience.While geophysical methods for first-order coastal properties monitoring have gained traction in academia[2,3],traditional monitoring techniques are limited by sparse and unevenly distributed observation stations,failing to meet the needs for detailed regional monitoring.Moreover,the complex social and cultural environments of coastal cities challenge sustained and intensive monitoring efforts.
基金support under the National Recovery and Resilience Plan(NRRP)Mission 4,Component 2,Investment 1.1,Call for tender No.104 published on February 2,2022 by the Italian Ministry of University and Research(MUR)+2 种基金funded by the European Union e Next GenerationEUe Project Title SteeRing GroundwatEr Electro-bioremediAtion with ConducTIVe ParticlEs(REACTIVE)e CUP:B53D23018110006-Grant Assignment Decree No.1048 adopted on July 14,2023 by the Italian Ministry of University and Research(MUR).UM acknowledges Villum Foundation(grant n.VIL50414)the Grundfos Foundation(grant n.2017-025)LP and GC acknowledge The Geosciences for Sustainable Development project(Budget Ministero dell'Universita e della Ricerca-Dipartimenti di Eccellenza 2023-2027,C93C23002690001).
文摘Microbial electrochemical technologies(MET)can remove a variety of organic and inorganic pollutants from contaminated groundwater.However,despite significant laboratory-scale successes over the past decade,field-scale applications remain limited.We hypothesize that enhancing the electrochemical conductivity of the soil surrounding electrodes could be a groundbreaking and cost-effective alternative to deploying numerous high-surface-area electrodes in short distances.This could be achieved by injecting environmentally safe iron-or carbon-based conductive(nano)particles into the aquifer.Upon transport and deposition onto soil grains,these particles create an electrically conductive zone that can be exploited to control and fine-tune the delivery of electron donors or acceptors over large distances,thereby driving the process more efficiently.Beyond extending the radius of influence of electrodes,these diffuse electro-conductive zones(DECZ)could also promote the development of syntrophic anaerobic communities that degrade contaminants via direct interspecies electron transfer(DIET).In this review,we present the state-of-the-art in applying conductive materials for MET and DIET-based applications.We also provide a comprehensive overview of the physicochemical properties of candidate electrochemically conductive materials and related injection strategies suitable for field-scale implementation.Finally,we illustrate and critically discuss current and prospective electrochemical and geophysical methods for measuring soil electronic conductivitydboth in the laboratory and in the fielddbefore and after injection practices,which are crucial for determining the extent of DECZ.This review article provides critical information for a robust design and in situ implementation of groundwater electro-bioremediation processes.
