Victor E. Infante-Pacheco, J. C. Montalvo-Arrieta, I. N. León, F. Velasco-Tapia
Several approaches can be taken to conduct seismic data inversion. However, usually, these approaches are unable to distinguish vertical and horizontal heterogeneities. Seismic inversion through the singular value decomposition (SVD) method offers an adequate and simple way to improve these traditional inversion models. For this study P and S wave data were acquired at a site located in northeastern Mexico, obtaining their travel times. An inversion algorithm involving the SVD analysis was then developed to establish the seismic velocities of the lithological units. Further, images of compressional and shear-wave velocities ( Vp and Vs, respectively), Vp/ Vs ratio, and elastic moduli (bulk, shear and Young's moduli, Lamé's constant, and Poisson's ratio) were obtained. These were compared with two geotechnical soundings positioned over a geophysical profile line. The geological features of the exposed units were recognized on some trenches. Further, seismic images demonstrated correlations with the thickness and distribution of the geological units. Unconsolidated sediments and fine-grain clastic rocks (in the Méndez formation) were clearly distinguished by the high velocity contrast. SVD seismic inversion has shown the ability to distinguish small physical heterogeneities of shallow geological units. Its application in civil engineering, hydrogeology, and to solve soil pollution problems can be relevant.
{"title":"Improvement of Shallow Seismic Characterization Using the Singular Value Decomposition (SVD) Method in Seismic Data Inversion: A Case Study of a Site in Northeast Mexico","authors":"Victor E. Infante-Pacheco, J. C. Montalvo-Arrieta, I. N. León, F. Velasco-Tapia","doi":"10.32389/jeeg20-037","DOIUrl":"https://doi.org/10.32389/jeeg20-037","url":null,"abstract":"Several approaches can be taken to conduct seismic data inversion. However, usually, these approaches are unable to distinguish vertical and horizontal heterogeneities. Seismic inversion through the singular value decomposition (SVD) method offers an adequate and simple way to improve these traditional inversion models. For this study P and S wave data were acquired at a site located in northeastern Mexico, obtaining their travel times. An inversion algorithm involving the SVD analysis was then developed to establish the seismic velocities of the lithological units. Further, images of compressional and shear-wave velocities ( Vp and Vs, respectively), Vp/ Vs ratio, and elastic moduli (bulk, shear and Young's moduli, Lamé's constant, and Poisson's ratio) were obtained. These were compared with two geotechnical soundings positioned over a geophysical profile line. The geological features of the exposed units were recognized on some trenches. Further, seismic images demonstrated correlations with the thickness and distribution of the geological units. Unconsolidated sediments and fine-grain clastic rocks (in the Méndez formation) were clearly distinguished by the high velocity contrast. SVD seismic inversion has shown the ability to distinguish small physical heterogeneities of shallow geological units. Its application in civil engineering, hydrogeology, and to solve soil pollution problems can be relevant.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"15 1","pages":"447-462"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87243838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
CSAMT exploration generally adopts a single dipole as the transmitter. The single dipole source has the apparent disadvantages–there are weak areas for all components, Eyand Hxare weak in the area where Exand Hyare reliable. Moreover, it is hard to deploy the source with a specific direction in a rugged mountainous area. Given the shortcomings of the single dipole source, multi-dipole sources are introduced into CSAMT exploration. Although the dipole sources follow the principle of vector synthesis, the length of the source in actual exploration can last for several kilometers and the offset is generally a few kilometers. In this case, the source can no longer be regarded as a single dipole in the near-field zone. The electromagnetic field in this region becomes relatively complicated. We first compare the similarities and differences of electromagnetic field generated by vector synthesis source and multi-dipole source through the Exradiation patterns. Then, we study the factors that affect electromagnetic response due to the substitution of the double-dipole source with the vector synthesis source. The measured EM fields is affected by the source length, frequency, the source angle, the offset, and the resistivity.Finally, we apply the double-dipole source to the 1D and 3D geological model and compare the difference between the electromagnetic field generated by the double-dipole source and that generated by the vector synthesis source. Usually, the difference is very obvious in the near-field zone, and is almost negligible in the far-field zone.
{"title":"A Comparative Study on the Difference between the Multi-dipole Sources and Vector Synthesis Source","authors":"Xianxiang Wang, Ju-Zhi Deng","doi":"10.32389/jeeg20-012","DOIUrl":"https://doi.org/10.32389/jeeg20-012","url":null,"abstract":"CSAMT exploration generally adopts a single dipole as the transmitter. The single dipole source has the apparent disadvantages–there are weak areas for all components, Eyand Hxare weak in the area where Exand Hyare reliable. Moreover, it is hard to deploy the source with a specific direction in a rugged mountainous area. Given the shortcomings of the single dipole source, multi-dipole sources are introduced into CSAMT exploration. Although the dipole sources follow the principle of vector synthesis, the length of the source in actual exploration can last for several kilometers and the offset is generally a few kilometers. In this case, the source can no longer be regarded as a single dipole in the near-field zone. The electromagnetic field in this region becomes relatively complicated. We first compare the similarities and differences of electromagnetic field generated by vector synthesis source and multi-dipole source through the Exradiation patterns. Then, we study the factors that affect electromagnetic response due to the substitution of the double-dipole source with the vector synthesis source. The measured EM fields is affected by the source length, frequency, the source angle, the offset, and the resistivity.Finally, we apply the double-dipole source to the 1D and 3D geological model and compare the difference between the electromagnetic field generated by the double-dipole source and that generated by the vector synthesis source. Usually, the difference is very obvious in the near-field zone, and is almost negligible in the far-field zone.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"35 1","pages":"529-543"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88451748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohammad Ali Iravani, J. Deparis, H. Davarzani, S. Colombano, R. Guérin, A. Maineult
The effective techniques for remediation of sites polluted by dense non-aqueous phase liquids (DNAPLs) remains a challenge. Among the various technical monitoring methods, there is an increasing interest in studying the geophysical characteristics of contaminated soils, as indicators of the progress in clean-up programs. This work sought to investigate the variation of the electrical complex resistivity and the relative permittivity by analyzing the results obtained from spectral induced polarization (SIP) and time domain reflectometry (TDR). Different series of measurements during drainage and imbibition of DNAPLs in porous media were done to validate the clean-up process on sites polluted by DNAPLs. Therefore, a methodology based on laboratory work was designed and carried out to study the electrical complex resistivity (both in magnitude and phase) in the frequency range 0.183 Hz to 20 kHz, and the relative dielectric permittivity at 70 MHz. The experiments were done on small 1D cells. In these cells, glass beads were used as a porous medium. Two different fluid couples, i.e., coal tar (CT)/water and canola oil (CO)/salty ethanol (SE), were used to produce two-phase flow. Our findings highlight that due to the high resistivity of CO and CT, an increase in water saturation led to decrease in amplitude and phase. Saturation change of SE had the same effect on resistivity but no relationship was found for phase and saturation for the mixture CO and SE. It is also showed that the complex resistivity and relative permittivity measurements were compatible with generalized Archie's law and complete complex refractive index method (CRIM) model as two empirical models for defining the correlation between the electrical resistivity, relative permittivity, and saturation of each phase in the multiphase porous medium.
{"title":"Complex Electrical Resistivity and Dielectric Permittivity Responses to Dense Non-aqueous Phase Liquids' Imbibition and Drainage in Porous Media: A Laboratory Study","authors":"Mohammad Ali Iravani, J. Deparis, H. Davarzani, S. Colombano, R. Guérin, A. Maineult","doi":"10.32389/jeeg20-050","DOIUrl":"https://doi.org/10.32389/jeeg20-050","url":null,"abstract":"The effective techniques for remediation of sites polluted by dense non-aqueous phase liquids (DNAPLs) remains a challenge. Among the various technical monitoring methods, there is an increasing interest in studying the geophysical characteristics of contaminated soils, as indicators of the progress in clean-up programs. This work sought to investigate the variation of the electrical complex resistivity and the relative permittivity by analyzing the results obtained from spectral induced polarization (SIP) and time domain reflectometry (TDR). Different series of measurements during drainage and imbibition of DNAPLs in porous media were done to validate the clean-up process on sites polluted by DNAPLs. Therefore, a methodology based on laboratory work was designed and carried out to study the electrical complex resistivity (both in magnitude and phase) in the frequency range 0.183 Hz to 20 kHz, and the relative dielectric permittivity at 70 MHz. The experiments were done on small 1D cells. In these cells, glass beads were used as a porous medium. Two different fluid couples, i.e., coal tar (CT)/water and canola oil (CO)/salty ethanol (SE), were used to produce two-phase flow. Our findings highlight that due to the high resistivity of CO and CT, an increase in water saturation led to decrease in amplitude and phase. Saturation change of SE had the same effect on resistivity but no relationship was found for phase and saturation for the mixture CO and SE. It is also showed that the complex resistivity and relative permittivity measurements were compatible with generalized Archie's law and complete complex refractive index method (CRIM) model as two empirical models for defining the correlation between the electrical resistivity, relative permittivity, and saturation of each phase in the multiphase porous medium.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"195 1","pages":"557-567"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79804265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Sherrod, H. Willever, K. Shollenberger, Corey Potter, R. Thorne, Ann Kline
The United States Revolutionary War (1775–1783) resulted in numerous mass burials in the eastern United States, with deaths occurring not just directly related to the battles fought, but also from disease, starvation, and exposure. Current information relating to these mass burials is often gathered from myths and rumors, leaving the truth of the historical aspects of that time period ambiguous. Geophysical techniques are increasingly utilized in archaeologic and forensic studies to locate unmarked burials. GPR, magnetics, and electrical resistivity have been used to successfully identify burial locations around the world in a non-invasive manner. This paper aims to illustrate how different burials of the US Revolutionary War period can be detected and characterized with geophysics, providing important knowledge of a better historical understanding of that time period, as well as optimizing equipment instrumentation and processing procedures for such targeted investigations. Three case studies of Revolutionary War Era mass burial sites in Pennsylvania, USA are described here: the Paoli Battlefield Memorial, the Old Charlestown Cemetery, and Saint Peter's Church in the Great Valley. These sites are within 9 km of each other and have historic records that suggest mass burials during this period. Results show GPR to provide the most useful data overall, with supporting information gathered from the supplemental geophysical techniques of magnetometry and resistivity. 2D profiles tend to provide a more valuable image of the subsurface than 3D slices. Larger burials leave a greater footprint and have a higher chance of causing a geophysical disturbance that can be measured more than 200 years after the burial. Soil moisture content and vegetation type can impact quality of results. Study implications demonstrate the challenges and potential usefulness of geophysical techniques to successfully locate and characterize mass burials of this time period.
{"title":"Geophysical Investigations of United States Revolutionary War Era (1777–1778) Mass Burial Sites in Pennsylvania, USA","authors":"L. Sherrod, H. Willever, K. Shollenberger, Corey Potter, R. Thorne, Ann Kline","doi":"10.32389/jeeg20-023","DOIUrl":"https://doi.org/10.32389/jeeg20-023","url":null,"abstract":"The United States Revolutionary War (1775–1783) resulted in numerous mass burials in the eastern United States, with deaths occurring not just directly related to the battles fought, but also from disease, starvation, and exposure. Current information relating to these mass burials is often gathered from myths and rumors, leaving the truth of the historical aspects of that time period ambiguous. Geophysical techniques are increasingly utilized in archaeologic and forensic studies to locate unmarked burials. GPR, magnetics, and electrical resistivity have been used to successfully identify burial locations around the world in a non-invasive manner. This paper aims to illustrate how different burials of the US Revolutionary War period can be detected and characterized with geophysics, providing important knowledge of a better historical understanding of that time period, as well as optimizing equipment instrumentation and processing procedures for such targeted investigations. Three case studies of Revolutionary War Era mass burial sites in Pennsylvania, USA are described here: the Paoli Battlefield Memorial, the Old Charlestown Cemetery, and Saint Peter's Church in the Great Valley. These sites are within 9 km of each other and have historic records that suggest mass burials during this period. Results show GPR to provide the most useful data overall, with supporting information gathered from the supplemental geophysical techniques of magnetometry and resistivity. 2D profiles tend to provide a more valuable image of the subsurface than 3D slices. Larger burials leave a greater footprint and have a higher chance of causing a geophysical disturbance that can be measured more than 200 years after the burial. Soil moisture content and vegetation type can impact quality of results. Study implications demonstrate the challenges and potential usefulness of geophysical techniques to successfully locate and characterize mass burials of this time period.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"65 1","pages":"477-496"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84436600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Editor's Foreword","authors":"D. Rucker","doi":"10.32389/jeeg20-999","DOIUrl":"https://doi.org/10.32389/jeeg20-999","url":null,"abstract":"","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"418 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77774139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reinforced concrete is a versatile modern construction material. Despite its advantages as a composite material, corrosion of the embedded reinforcing steel leads to infrastructure deterioration and loss of service. Non-Destructive Testing (NDT) methods are required to quantify the reinforcement condition, and to help manage human and financial risks arising from unexpected outright failure or service restrictions. Reinforcement condition can be assessed using a novel, time- and cost-efficient NDT method based on the self-magnetic behaviour of ferromagnetic materials. In this study, the magnetic properties of three similar rebars, each having three similar sized longitudinal defects, are recorded and assessed through experiments and a numerical simulation model. Strong correspondence is demonstrated between the magnetic properties from numerical simulation and from the experimental objects. For instance, applying the experimentally obtained defect detection threshold to the mathematically simulated results allows accurate defect detection in the simulations, showing that self-magnetic behavior is a powerful tool for condition assessment of ferromagnetic reinforcing materials.
{"title":"Magnetic Data Pattern Features at Longitudinal Defect Sites in Rebars Scanned by a Passive Magnetic Inspection Technology","authors":"M. Mosharafi, S. Mahbaz, M. Dusseault","doi":"10.32389/jeeg20-031","DOIUrl":"https://doi.org/10.32389/jeeg20-031","url":null,"abstract":"Reinforced concrete is a versatile modern construction material. Despite its advantages as a composite material, corrosion of the embedded reinforcing steel leads to infrastructure deterioration and loss of service. Non-Destructive Testing (NDT) methods are required to quantify the reinforcement condition, and to help manage human and financial risks arising from unexpected outright failure or service restrictions. Reinforcement condition can be assessed using a novel, time- and cost-efficient NDT method based on the self-magnetic behaviour of ferromagnetic materials. In this study, the magnetic properties of three similar rebars, each having three similar sized longitudinal defects, are recorded and assessed through experiments and a numerical simulation model. Strong correspondence is demonstrated between the magnetic properties from numerical simulation and from the experimental objects. For instance, applying the experimentally obtained defect detection threshold to the mathematically simulated results allows accurate defect detection in the simulations, showing that self-magnetic behavior is a powerful tool for condition assessment of ferromagnetic reinforcing materials.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"16 1","pages":"513-528"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73818395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents an improved nature-based algorithm, namely multivariable modified teaching learning based optimization (MM-TLBO) algorithm, as in an iterative process can estimates the best values for the model parameters in a multi-objective problem. The algorithm works in two computational phases: the teacher phase and the learner phase. The major purpose of the MM-TLBO algorithm is to improve the value of the learners and thus, improving the value of the model parameters which leads to the optimal solution. The variables of each learner (model) are the radius ( R), depth ( h), shape factor ( q), density contrast ( ρ) and axis location ( x0) parameters. We apply MM-TLBO and TLBO methods for the residual gravity anomalies caused by the buried masses with a simple geometry such as spheres, horizontal and vertical cylinders. The efficiency of these methods are also tested by noise corruption synthetic data, as the acceptable results were obtained. The obtained results indicate the better performance the MM-TLBO algorithm than the TLBO algorithm. We have utilized the MM-TLBO for the interpretation of the six residual gravity anomaly profiles from Iran, USA, Sweden and Senegal. The advantage of the MM-TLBO inversion is that it can estimates the best solutions very fast without falling into local minimum and reaches to a premature convergence. The considered primary population for the synthetic and real gravity data are thirty and fifty models. The results show which this method is able to achieve the optimal responses even if a small population of learners had been considered.
{"title":"Multivariable Modified Teaching Learning Based Optimization (MM-TLBO) Algorithm for Inverse Modeling of Residual Gravity Anomaly Generated by Simple Geometric Shapes","authors":"A. Eshaghzadeh, A. Hajian","doi":"10.32389/jeeg20-003","DOIUrl":"https://doi.org/10.32389/jeeg20-003","url":null,"abstract":"This paper presents an improved nature-based algorithm, namely multivariable modified teaching learning based optimization (MM-TLBO) algorithm, as in an iterative process can estimates the best values for the model parameters in a multi-objective problem. The algorithm works in two computational phases: the teacher phase and the learner phase. The major purpose of the MM-TLBO algorithm is to improve the value of the learners and thus, improving the value of the model parameters which leads to the optimal solution. The variables of each learner (model) are the radius ( R), depth ( h), shape factor ( q), density contrast ( ρ) and axis location ( x0) parameters. We apply MM-TLBO and TLBO methods for the residual gravity anomalies caused by the buried masses with a simple geometry such as spheres, horizontal and vertical cylinders. The efficiency of these methods are also tested by noise corruption synthetic data, as the acceptable results were obtained. The obtained results indicate the better performance the MM-TLBO algorithm than the TLBO algorithm. We have utilized the MM-TLBO for the interpretation of the six residual gravity anomaly profiles from Iran, USA, Sweden and Senegal. The advantage of the MM-TLBO inversion is that it can estimates the best solutions very fast without falling into local minimum and reaches to a premature convergence. The considered primary population for the synthetic and real gravity data are thirty and fifty models. The results show which this method is able to achieve the optimal responses even if a small population of learners had been considered.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"96 1","pages":"463-476"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85862077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiawei Li, Zhen-zhu Xi, Chen Xingpeng, Wang He, Long Xia, Z. Sheng, Wang Liang
An induction coil sensor (ICS) is important for measuring low-frequency (DC-1kHz) geomagnetic field. The accuracy of the preamplifier is one key factor determining the performance of the sensor. But the preamplifier is susceptible to 1/ f noise, offset voltage and drift. In order to eliminate these influences, a preamplifier circuit with three amplifier stages based on chopper technology has been designed, and its performance has been tested. The results show that: 1) The 1/ f noise corner frequency is 3 mHz, the equivalent input voltage noise (EIVN) level of the circuit is [Formula: see text] and [Formula: see text]; 2) The equivalent input current noise (EICN) level of the circuit is [Formula: see text]; 3) The offset voltage is about 600 nV, and the time drift performance is excellent. In conclusion, the preamplifier circuit has characteristics of ultralow noise, low offset voltage and low time drift. It can effectively amplify low-frequency weak geomagnetic signals from 1 mHz to 1 kHz and provides excellent performance for low-frequency ICS.
{"title":"Ultralow Noise Low Offset Chopper Amplifier for Induction Coil Sensor to Detect Geomagnetic Field of 1 mHz to 1 kHz","authors":"Jiawei Li, Zhen-zhu Xi, Chen Xingpeng, Wang He, Long Xia, Z. Sheng, Wang Liang","doi":"10.32389/jeeg20-014","DOIUrl":"https://doi.org/10.32389/jeeg20-014","url":null,"abstract":"An induction coil sensor (ICS) is important for measuring low-frequency (DC-1kHz) geomagnetic field. The accuracy of the preamplifier is one key factor determining the performance of the sensor. But the preamplifier is susceptible to 1/ f noise, offset voltage and drift. In order to eliminate these influences, a preamplifier circuit with three amplifier stages based on chopper technology has been designed, and its performance has been tested. The results show that: 1) The 1/ f noise corner frequency is 3 mHz, the equivalent input voltage noise (EIVN) level of the circuit is [Formula: see text] and [Formula: see text]; 2) The equivalent input current noise (EICN) level of the circuit is [Formula: see text]; 3) The offset voltage is about 600 nV, and the time drift performance is excellent. In conclusion, the preamplifier circuit has characteristics of ultralow noise, low offset voltage and low time drift. It can effectively amplify low-frequency weak geomagnetic signals from 1 mHz to 1 kHz and provides excellent performance for low-frequency ICS.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"572 1","pages":"497-511"},"PeriodicalIF":1.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85046757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Methane is a companion of coal formations, and it has a complex interaction with the coal seam and its surrounding rock. Methane not only has characteristics of weakening coal strength but also influences the characteristics of electromagnetic radiation (EMR) during coal damage. In this paper, a drop hammer impact test method was introduced to conduct dynamic loading on gas-containing coal samples with different pore pressure treatments. Then, a typical high gas and outburst coal mining workface was selected to carry out a long-term field site experiment. The EMR signal features collected during both the experimental tests and field site tests were analyzed to investigate the influence of methane. The results show that: i) there is a clear correlation between the pore pressure and the transient EMR signal characteristics during the failure of the gas-containing coal sample; with the increase in the pore pressure, the overall intensity, duration and total energy of the EMR signal decreases accordingly; ii) the EMR signals measured in the two directions at the site have great consistency; these signals are cluster pulses with energy in the range of 0.1 mJ–2 mJ; iii) the energy, pulse counts, and duration of the EMR signal have good positive correlation with the blasting charges; and iv) with the increase in the gas content in the coal seam, the amplitude and energy of the EMR signal induced by the blasting vibrations are significantly decreased; however, the main frequency of the signal is not substantially affected. This study provides a basic demonstration to prove the effect of methane on the dynamic rupture of coal and the features of the produced EMR, which are of great significance to the application of EMR to conducting early warning of outbursts.
{"title":"Transient Electromagnetic Signal from Impact Damages of an Inherent Gas-containing Coal Seam","authors":"Xiaomeng Xu, Xiaodong Liu, Qiang Wang, Wenwen Zhao, Lihui Dong, Haining Wang","doi":"10.32389/jeeg19-103","DOIUrl":"https://doi.org/10.32389/jeeg19-103","url":null,"abstract":"Methane is a companion of coal formations, and it has a complex interaction with the coal seam and its surrounding rock. Methane not only has characteristics of weakening coal strength but also influences the characteristics of electromagnetic radiation (EMR) during coal damage. In this paper, a drop hammer impact test method was introduced to conduct dynamic loading on gas-containing coal samples with different pore pressure treatments. Then, a typical high gas and outburst coal mining workface was selected to carry out a long-term field site experiment. The EMR signal features collected during both the experimental tests and field site tests were analyzed to investigate the influence of methane. The results show that: i) there is a clear correlation between the pore pressure and the transient EMR signal characteristics during the failure of the gas-containing coal sample; with the increase in the pore pressure, the overall intensity, duration and total energy of the EMR signal decreases accordingly; ii) the EMR signals measured in the two directions at the site have great consistency; these signals are cluster pulses with energy in the range of 0.1 mJ–2 mJ; iii) the energy, pulse counts, and duration of the EMR signal have good positive correlation with the blasting charges; and iv) with the increase in the gas content in the coal seam, the amplitude and energy of the EMR signal induced by the blasting vibrations are significantly decreased; however, the main frequency of the signal is not substantially affected. This study provides a basic demonstration to prove the effect of methane on the dynamic rupture of coal and the features of the produced EMR, which are of great significance to the application of EMR to conducting early warning of outbursts.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"85 1","pages":"341-354"},"PeriodicalIF":1.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90836637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Groundwater constitutes the main source of the freshwater in Ras-Matarma, Sinai, which necessitates optimized management of it. In this context, geophysical ground magnetic, Schlumberger resistivity inversion, remote sensing (RS), geographic information system (GIS), and pumping tests were conducted. The magnetic survey comprised 56 profiles, whereas, Schlumberger resistivity survey were 27 VES. GIS and RS were implemented for watershed analyses in the area. Interpretation of the magnetic data separated significantly the shallow and deep structures with depths ranged from 300 to 1400 m. Qualitative and quantitative modelling of the inverted resistivity data demarcated effectively the fresh aquifer with true resistivity and thickness ranged from 22 to 210 ohm.m and 2 to 80 m, respectively. GIS aggregated all the aforementioned results along with electric and hydraulic parameters of the fresh aquifer.
{"title":"Magnetic and Geo-electrical Geophysical Techniques for Subsurface Delineation and Groundwater Assessment in Ras Matarma, Sinai","authors":"Noha A. Hassan, Mohamed H. Khalil, M. Ghaleb","doi":"10.32389/jeeg20-007","DOIUrl":"https://doi.org/10.32389/jeeg20-007","url":null,"abstract":"Groundwater constitutes the main source of the freshwater in Ras-Matarma, Sinai, which necessitates optimized management of it. In this context, geophysical ground magnetic, Schlumberger resistivity inversion, remote sensing (RS), geographic information system (GIS), and pumping tests were conducted. The magnetic survey comprised 56 profiles, whereas, Schlumberger resistivity survey were 27 VES. GIS and RS were implemented for watershed analyses in the area. Interpretation of the magnetic data separated significantly the shallow and deep structures with depths ranged from 300 to 1400 m. Qualitative and quantitative modelling of the inverted resistivity data demarcated effectively the fresh aquifer with true resistivity and thickness ranged from 22 to 210 ohm.m and 2 to 80 m, respectively. GIS aggregated all the aforementioned results along with electric and hydraulic parameters of the fresh aquifer.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"1 1","pages":"425-431"},"PeriodicalIF":1.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78314685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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