Integration between magnetic and gravity data at the Zelten platform, the southeast part of Sirt Basin Libya. Zelten Platform is first discovered oil field in Libya. It shows numerous geological structures of different tectonic events. The methods adopted can assist in locating the hidden subsurface structures. The platform is characterized by the NW-SE trending rift that belongs to the Early Cretaceous age (during the collapse of Sirt Arch). The study aimed to define the structural geology that assisted in the development of future exploration in this area. The analyses utilized several filtering and transformation algorithms to help in structural modeling. For instance, the total horizontal gradient and tilt angle derivative were applied for the edge detection of the tectonic boundaries. The results show NW-SE and NNW-SSE patterns that represents faults that controlled the positions of the troughs and platforms at the Sirt basin. On the other hand, Euler deconvolution and 2D forward modeling were utilized to determine the depth of the basement. The Integrated models deduced revealed that the main faults trends are NW-SE which refer to the rift phases and crustal extension period that occurred during the Mesozoic time (early cretaceous). Also, the basement depth ranges from 6.5 km to 8 km according to the structures that affected the study
{"title":"Structural framework of the Zelten platform, south Sirte Basin, Libya using Potential Fields modelling","authors":"Abdelhakim Eshanibli","doi":"10.13168/agg.2020.0017","DOIUrl":"https://doi.org/10.13168/agg.2020.0017","url":null,"abstract":"Integration between magnetic and gravity data at the Zelten platform, the southeast part of Sirt Basin Libya. Zelten Platform is first discovered oil field in Libya. It shows numerous geological structures of different tectonic events. The methods adopted can assist in locating the hidden subsurface structures. The platform is characterized by the NW-SE trending rift that belongs to the Early Cretaceous age (during the collapse of Sirt Arch). The study aimed to define the structural geology that assisted in the development of future exploration in this area. The analyses utilized several filtering and transformation algorithms to help in structural modeling. For instance, the total horizontal gradient and tilt angle derivative were applied for the edge detection of the tectonic boundaries. The results show NW-SE and NNW-SSE patterns that represents faults that controlled the positions of the troughs and platforms at the Sirt basin. On the other hand, Euler deconvolution and 2D forward modeling were utilized to determine the depth of the basement. The Integrated models deduced revealed that the main faults trends are NW-SE which refer to the rift phases and crustal extension period that occurred during the Mesozoic time (early cretaceous). Also, the basement depth ranges from 6.5 km to 8 km according to the structures that affected the study","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"229-236"},"PeriodicalIF":0.9,"publicationDate":"2020-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47288550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When using the PPP method, it is recommended to take into account the tropospheric influences for obtaining reliable estimates. Global Navigation Satellite System (GNSS) observations taken at low elevation suffer more strongly from atmospheric, antenna phase center variation and multipath effects, hence the observations are noisier than those at higher elevation angle, but they are essential to decorrelate the estimated station height and tropospheric zenith delay (ZTD). To relate the ZTD in the direction of an observation, the so-called mapping function (MF) are used. In this article the influence of different mapping function was studieds such as: Niell mapping function (NMF), Global Mapping Function (GMF) in conjunction with the Global Pressure and Temperature 2 -GPT2, Vienna Mapping Function 1 and no mapping function. The MF were used at different elevation cutoff angles – 50, 70, 100 and 150. The impact was analyzed: a) on the postfit residuals of the ionospheric free combination for phase (LC) and for pseudorange (PC), b) daily variability for North, East and Up component; c) evaluation of coordinates repeatability and how they are affected by the changes of the cutoff elevation angle and mapping function. The analyzed data was taken from 4 EUREF stations for a period of one month October 2015. By using the VMF1 mapping function, the lowest value was obtained for the postfit residuals of the LC combination for all the stations. The difference in daily variation between each individual solution for the horizontal component is at the level of ~0.3 ÷ 0.5 mm, with smaller effect on the East component compared to North, whereas the Up component is at the level of ~1.0 ÷ 1.5 mm. The standard deviation (SD) is used as a measure of station position repeatability and the results suggested that for high precision determination a cutoff elevation angle of 100 should be used. Although at low elevation 50 and 70 – the VMF1 performs better than the GMF/GPT2 and NMF, after 100 the GMF/GPT2 is strongly in agreement with VMF1 and after 150 the NMF shows similar results as VMF1 and GMF/GPT2. ARTICLE INFO
在使用购买力平价方法时，建议考虑对流层的影响，以获得可靠的估计。全球导航卫星系统(GNSS)低海拔观测数据受大气、天线相位中心变化和多径效应的影响更大，因此观测数据比高海拔观测数据噪声更大，但它们对解相关估算站高和对流层天顶延迟(ZTD)至关重要。为了在观测方向上关联ZTD，使用了所谓的映射函数(MF)。本文研究了Niell映射函数(NMF)、Global mapping function (GMF)结合Global Pressure and Temperature 2 -GPT2、Vienna mapping function 1、no mapping function等不同映射函数的影响。在不同的仰角截止角- 50、70、100和150时使用MF。分析了其影响:a)对相位(LC)和伪距(PC)的电离层自由组合的拟合后残差，b)北、东、上分量的日变率;C)评价坐标的可重复性，以及它们如何受到截止仰角和成图函数变化的影响。所分析的数据来自4个EUREF站点，时间为2015年10月的一个月。利用VMF1映射函数，得到所有站点LC组合的后拟合残差的最小值。水平分量各单项溶液的日变化差为~0.3 ÷ 0.5 mm，东分量的影响小于北分量，而上分量的日变化差为~1.0 ÷ 1.5 mm。采用标准偏差(SD)作为测站位置重复性的度量，结果表明，为实现高精度测定，应采用100的截止仰角。虽然在低海拔50和70 -时，VMF1的表现优于GMF/GPT2和NMF，但在100 -后，GMF/GPT2与VMF1非常一致，而在150 -后，NMF的结果与VMF1和GMF/GPT2相似。条信息
{"title":"The impact of tropospheric mapping function on PPP determination for one-month period","authors":"S. Nistor","doi":"10.13168/agg.2020.0018","DOIUrl":"https://doi.org/10.13168/agg.2020.0018","url":null,"abstract":"When using the PPP method, it is recommended to take into account the tropospheric influences for obtaining reliable estimates. Global Navigation Satellite System (GNSS) observations taken at low elevation suffer more strongly from atmospheric, antenna phase center variation and multipath effects, hence the observations are noisier than those at higher elevation angle, but they are essential to decorrelate the estimated station height and tropospheric zenith delay (ZTD). To relate the ZTD in the direction of an observation, the so-called mapping function (MF) are used. In this article the influence of different mapping function was studieds such as: Niell mapping function (NMF), Global Mapping Function (GMF) in conjunction with the Global Pressure and Temperature 2 -GPT2, Vienna Mapping Function 1 and no mapping function. The MF were used at different elevation cutoff angles – 50, 70, 100 and 150. The impact was analyzed: a) on the postfit residuals of the ionospheric free combination for phase (LC) and for pseudorange (PC), b) daily variability for North, East and Up component; c) evaluation of coordinates repeatability and how they are affected by the changes of the cutoff elevation angle and mapping function. The analyzed data was taken from 4 EUREF stations for a period of one month October 2015. By using the VMF1 mapping function, the lowest value was obtained for the postfit residuals of the LC combination for all the stations. The difference in daily variation between each individual solution for the horizontal component is at the level of ~0.3 ÷ 0.5 mm, with smaller effect on the East component compared to North, whereas the Up component is at the level of ~1.0 ÷ 1.5 mm. The standard deviation (SD) is used as a measure of station position repeatability and the results suggested that for high precision determination a cutoff elevation angle of 100 should be used. Although at low elevation 50 and 70 – the VMF1 performs better than the GMF/GPT2 and NMF, after 100 the GMF/GPT2 is strongly in agreement with VMF1 and after 150 the NMF shows similar results as VMF1 and GMF/GPT2. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"237-252"},"PeriodicalIF":0.9,"publicationDate":"2020-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44394650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dynamic soil properties are important parameters for the design of structures subjected to various dynamic/cyclic loading such as earthquake which can be obtained by in situ and laboratory measurements. Numerous empirical and mathematical models have been proposed to predict the dynamic properties of soils, including maximum shear modulus (Gmax), normalized shear modulus (G/Gmax γ) curve, reference shear strain (γr), minimum damping ratio (Dmin) and damping ratio (D γ) curve. However, the majority of the existing models were proposed for specific soil types, loading characteristics, initial soil fabrics and strain ranges. This paper proposes five universal models to estimate the Gmax, γr and Dmin values, and also G/Gmax – γ and D – γ curves using a database that contains 117 tests on 5 different granular soils. The proposed models include the effect of grading characteristics, void ratio, mean effective confining pressure, consolidation stress ratio (KC) and specimen preparation method. The models are validated using experimental data from previous studies for granular soils. The results indicate that the proposed models are capable of evaluating the dynamic properties of granular soil. ARTICLE INFO
{"title":"Universal model forms for predicting the dynamic properties of granular soils","authors":"M. Bayat","doi":"10.13168/agg.2020.0016","DOIUrl":"https://doi.org/10.13168/agg.2020.0016","url":null,"abstract":"Dynamic soil properties are important parameters for the design of structures subjected to various dynamic/cyclic loading such as earthquake which can be obtained by in situ and laboratory measurements. Numerous empirical and mathematical models have been proposed to predict the dynamic properties of soils, including maximum shear modulus (Gmax), normalized shear modulus (G/Gmax γ) curve, reference shear strain (γr), minimum damping ratio (Dmin) and damping ratio (D γ) curve. However, the majority of the existing models were proposed for specific soil types, loading characteristics, initial soil fabrics and strain ranges. This paper proposes five universal models to estimate the Gmax, γr and Dmin values, and also G/Gmax – γ and D – γ curves using a database that contains 117 tests on 5 different granular soils. The proposed models include the effect of grading characteristics, void ratio, mean effective confining pressure, consolidation stress ratio (KC) and specimen preparation method. The models are validated using experimental data from previous studies for granular soils. The results indicate that the proposed models are capable of evaluating the dynamic properties of granular soil. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"217-227"},"PeriodicalIF":0.9,"publicationDate":"2020-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47131940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the general tropospheric tomography model, the tomographic area is divided into a large number of voxels, which provides convenience for reconstructing tomographic observation equations. However, due to the defect of GNSS acquisition geometry, there are plenty of empty voxels for any tomographic epoch. Moreover, an unreasonable assumption that water vapor density is constant within a voxel was imposed on the tomographic model. In this study, we proposed an improved method based on the dynamic node parameterized algorithm to solve both key problems. The proposed approach first tries to select effective GNSS signals and determines the dynamic scope of the tomographic area using the dynamic algorithm. The parameterization of the tomography model is performed by a cubic spline formula and Gauss weighted function. Additionally, a piecewise linear fitting method based on Newton-Cotes interpolation is introduced to estimate the tomographic observation of slant water vapor (SWV). The experimental results show that the average number of effective signals increased by 32.33 % and the mean RMSE of the tomographic results is decreased by 45 % with the proposed method. Further, compared with the tomographic results of the general method, the improved solutions have a more centralized distribution and a smaller bias. ARTICLE INFO
{"title":"An improved tropospheric tomography method based on the dynamic node parametrized algorithm","authors":"Wenyuan Zhang","doi":"10.13168/agg.2020.0014","DOIUrl":"https://doi.org/10.13168/agg.2020.0014","url":null,"abstract":"In the general tropospheric tomography model, the tomographic area is divided into a large number of voxels, which provides convenience for reconstructing tomographic observation equations. However, due to the defect of GNSS acquisition geometry, there are plenty of empty voxels for any tomographic epoch. Moreover, an unreasonable assumption that water vapor density is constant within a voxel was imposed on the tomographic model. In this study, we proposed an improved method based on the dynamic node parameterized algorithm to solve both key problems. The proposed approach first tries to select effective GNSS signals and determines the dynamic scope of the tomographic area using the dynamic algorithm. The parameterization of the tomography model is performed by a cubic spline formula and Gauss weighted function. Additionally, a piecewise linear fitting method based on Newton-Cotes interpolation is introduced to estimate the tomographic observation of slant water vapor (SWV). The experimental results show that the average number of effective signals increased by 32.33 % and the mean RMSE of the tomographic results is decreased by 45 % with the proposed method. Further, compared with the tomographic results of the general method, the improved solutions have a more centralized distribution and a smaller bias. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"191-206"},"PeriodicalIF":0.9,"publicationDate":"2020-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43239243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A refined triple-frequency cycle slip detection and repair algorithm for GPS/BDS undifferenced observables under high ionospheric disturbances is proposed. In this method, three linearindependent optimal observables combinations for GPS/BDS are selected. The residual ionospheric delay estimated from a “calculation-prediction mechanism”, namely flexibly determine whether to calculate delay by observables themselves or to predict delay by a feedforward neural network (FNN), is used to compensate for the detection values. Additionally, we devise an adaptive detection threshold based on actual noise level to detect the cycle slip, and adopt the modified least-square decorrelation adjustment (MLAMBDA) to fix integer cycle slip. The performance of the proposed algorithm was tested with observables at 30 s sampling rate in a 2-day geomagnetic storm period. Results showed that the proposed algorithm can detect and repair all kinds of cycle slips as small as one cycle in the case of high ionospheric disturbances. No false repairs are generated despite the occurrence of very few misjudgments. ARTICLE INFO Article history: Received 7 December 2019 Accepted 4 February 2020 Available online 16 April 2020
{"title":"GPS/BDS triple-frequency cycle slip detection and repair algorithm based on adaptive detection threshold and FNN-derived ionospheric delay compensation","authors":"Nijia Qian","doi":"10.13168/agg.2020.0010","DOIUrl":"https://doi.org/10.13168/agg.2020.0010","url":null,"abstract":"A refined triple-frequency cycle slip detection and repair algorithm for GPS/BDS undifferenced observables under high ionospheric disturbances is proposed. In this method, three linearindependent optimal observables combinations for GPS/BDS are selected. The residual ionospheric delay estimated from a “calculation-prediction mechanism”, namely flexibly determine whether to calculate delay by observables themselves or to predict delay by a feedforward neural network (FNN), is used to compensate for the detection values. Additionally, we devise an adaptive detection threshold based on actual noise level to detect the cycle slip, and adopt the modified least-square decorrelation adjustment (MLAMBDA) to fix integer cycle slip. The performance of the proposed algorithm was tested with observables at 30 s sampling rate in a 2-day geomagnetic storm period. Results showed that the proposed algorithm can detect and repair all kinds of cycle slips as small as one cycle in the case of high ionospheric disturbances. No false repairs are generated despite the occurrence of very few misjudgments. ARTICLE INFO Article history: Received 7 December 2019 Accepted 4 February 2020 Available online 16 April 2020","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"141-156"},"PeriodicalIF":0.9,"publicationDate":"2020-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43895016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Period and Q-factor of free core nutation based on different geophysical excitations and VLBI solutions","authors":"J. Vondrák","doi":"10.13168/agg.2020.0015","DOIUrl":"https://doi.org/10.13168/agg.2020.0015","url":null,"abstract":"","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"207-215"},"PeriodicalIF":0.9,"publicationDate":"2020-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44405193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mapping the thickness of Quaternary sediments in the Iska alluvial fan (central Slovenia) using microtremor method","authors":"L. Rupar","doi":"10.13168/agg.2020.0013","DOIUrl":"https://doi.org/10.13168/agg.2020.0013","url":null,"abstract":"","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"177-190"},"PeriodicalIF":0.9,"publicationDate":"2020-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43334794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Comparison of vertical deformation of the Earth_s surface obtained using GRACE_based GGMS and GNNS data _ a case study of South_Eastern Poland","authors":"Walyeldeen Godah","doi":"10.13168/agg.2020.0012","DOIUrl":"https://doi.org/10.13168/agg.2020.0012","url":null,"abstract":"","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"169-176"},"PeriodicalIF":0.9,"publicationDate":"2020-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41368470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The study of the mechanical properties of frozen rock is a basic problem that humans have to face in artificial low-temperature rock engineering and cold region rock engineering. There are few literatures on the dynamic constitutive models of frozen rocks under low-temperature gradients at home and abroad. In this paper, the constitutive model of water-saturated marble under the coupling effects of uniaxial impact compressive load and low-temperature is studied by theoretical analysis and experimental verification. Based on the theory of mechanical element combination, a rock constitutive model considering strain rate effect, damage softening effect and low-temperature effect is established, and the model parameters are determined by fitting method. The dynamic stress-strain curve of water-saturated marble at -30 °C is predicted. The predicted results are in good agreement with the experimental results and the concordance correlation coefficient is 0.984092. The relevant results of this paper can provide a theoretical reference for the excavation and protection of rock engineering under negative temperature. ARTICLE INFO Article history: Received 30 November 2019 Accepted 5 February 2020 Available online 5 March 2020
{"title":"Constitutive model of water-saturated marble under coupling effects of uniaxial impact compressive loading and low-temperature","authors":"Junzhe Li","doi":"10.13168/agg.2020.0011","DOIUrl":"https://doi.org/10.13168/agg.2020.0011","url":null,"abstract":"The study of the mechanical properties of frozen rock is a basic problem that humans have to face in artificial low-temperature rock engineering and cold region rock engineering. There are few literatures on the dynamic constitutive models of frozen rocks under low-temperature gradients at home and abroad. In this paper, the constitutive model of water-saturated marble under the coupling effects of uniaxial impact compressive load and low-temperature is studied by theoretical analysis and experimental verification. Based on the theory of mechanical element combination, a rock constitutive model considering strain rate effect, damage softening effect and low-temperature effect is established, and the model parameters are determined by fitting method. The dynamic stress-strain curve of water-saturated marble at -30 °C is predicted. The predicted results are in good agreement with the experimental results and the concordance correlation coefficient is 0.984092. The relevant results of this paper can provide a theoretical reference for the excavation and protection of rock engineering under negative temperature. ARTICLE INFO Article history: Received 30 November 2019 Accepted 5 February 2020 Available online 5 March 2020","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"155-166"},"PeriodicalIF":0.9,"publicationDate":"2020-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41499471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to quantitatively study the influence of temperature and confining pressure on brittle plasticity of granite, this paper reviews previous studies regarding quantitative calculation methods for the brittle-plastic behaviors of rocks and their mechanical characteristics under high temperatures and confining pressures. Combining the experimental results for temperatures and confining pressures with theoretical calculations of brittleness and plasticity allowed quantitative calculations and evaluations for the brittleness and plasticity of granite to be obtained. The main conclusions are as follows. (1) High temperatures lead to a transformation of granite from brittle failure to plastic failure. Comparing six conventional empirical equations from the literature, the B3 and B6 can more accurately describe the relationship between the brittleness and temperature of granite. (2) When the confining pressure σ3 is less than 20 MPa, the internal pore structure and fractures of granite are re-compacted and reduced, which gradually increases its brittleness. With the increasing confining pressure, the pore structure changes again after exceeding 20 MPa. This initiates new cracks, which ultimately leads to a decrease of the granite brittleness. (3) The abrupt temperature for the brittle-plastic transformation of granite is approximately 800 °C, and the brittle-plastic transformation of granite is mainly affected by temperature and not the confining pressure. ARTICLE INFO
{"title":"Quantitative analysis of the influence of temperature and confining pressure on brittleness of granite: A review","authors":"Fei Zhao","doi":"10.13168/agg.2020.0003","DOIUrl":"https://doi.org/10.13168/agg.2020.0003","url":null,"abstract":"In order to quantitatively study the influence of temperature and confining pressure on brittle plasticity of granite, this paper reviews previous studies regarding quantitative calculation methods for the brittle-plastic behaviors of rocks and their mechanical characteristics under high temperatures and confining pressures. Combining the experimental results for temperatures and confining pressures with theoretical calculations of brittleness and plasticity allowed quantitative calculations and evaluations for the brittleness and plasticity of granite to be obtained. The main conclusions are as follows. (1) High temperatures lead to a transformation of granite from brittle failure to plastic failure. Comparing six conventional empirical equations from the literature, the B3 and B6 can more accurately describe the relationship between the brittleness and temperature of granite. (2) When the confining pressure σ3 is less than 20 MPa, the internal pore structure and fractures of granite are re-compacted and reduced, which gradually increases its brittleness. With the increasing confining pressure, the pore structure changes again after exceeding 20 MPa. This initiates new cracks, which ultimately leads to a decrease of the granite brittleness. (3) The abrupt temperature for the brittle-plastic transformation of granite is approximately 800 °C, and the brittle-plastic transformation of granite is mainly affected by temperature and not the confining pressure. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"39-50"},"PeriodicalIF":0.9,"publicationDate":"2020-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43950811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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