Acta Geodynamica et Geomaterialia最新文献

{"title":"Assessment of multi-GNSS precise orbit and clock products from different analysis centers based on precise point positioning","authors":"Weiguo Li","doi":"10.13168/agg.2021.0027","DOIUrl":"https://doi.org/10.13168/agg.2021.0027","url":null,"abstract":"Performance of 24h static Precise Point Positioning (PPP) solutions based on multi-GNSS precise satellite orbit and clock products from four analysis centers and seven various constellation combinations was studied to evaluate their quality and characteristics. Data from ten European and four Chinese GNSS stations and 152 days long period from year 2020 were processed. Obtained coordinates were firstly compared with those provided by IGS final weekly combined solution. In Europe, the best agreement with this reference product was reached by solutions including Galileo signals, namely by a combination of GPS+GLONASS+Galileo systems with a mean RMS of 11 mm. This situation was different in China where inclusion of Galileo always led to worse results and the best agreement was achieved by a combination of GPS+GLONASS systems. Although product provided by German Research Center for Geosciences (GFZ) could be selected as the best performing over Europe and product by Center for Orbit Determination in Europe (CODE) over China, differences between individual precise products were mostly at a minimal level. Secondly, coordinates repeatability over the processed period was computed in order to assess the positioning stability. In this regard, the lowest values in both horizontal and vertical direction were reached by GPS+GLONASS solutions. From the perspective of precise products, the repeatability results were dependent on the selected constellation where mainly a specific behavior of product from Wuhan University (WUM) for Galileo system was observed. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"6 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66268290","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":"Mineralogical and textural influence on physico-mechanical properties of selected granitoids from Besham Syntaxis, Northern Pakistan","authors":"T. Ahmad","doi":"10.13168/agg.2021.0024","DOIUrl":"https://doi.org/10.13168/agg.2021.0024","url":null,"abstract":"The Dubair-Shang granitoids are the major intrusive bodies in Besham group and are exposed along the Karakoram Highway in Besham and lower Kohistan districts. A variety of these granitoid rocks have been investigated in terms of their petrographic features and physicomechanical properties. The studied rocks are classified into four different textural varieties including Dubair mylonitized (DM), Dubair coarse grained (DCG), Shang coarse grained (SCG) and Shang foliated (SF) granitoids based on field observations and petrographic features. Petrographically quartz, potash feldspar, plagioclase and biotite are the essential minerals present in all varieties in varying amount. Beside these hornblende, chlorite, epidote, ore mineral(s) and sphene are also present in the accessory amount. As a part of the present investigation some of the mechanical and physical properties including uniaxial compressive strength (UCS), uniaxial tensile strength (UTS), specific gravity, water absorption, total porosity, and Los Angeles abrasion were also determined. The combined approach of petrographic features with the physicomechanical investigation revealed that the textural characteristics and mineralogy have a significant influence on the physico-mechanical properties of the studied rocks. It is determined that modal percentage of minerals, degree of alteration, recrystallization, grain size and shape, types of grain boundary contacts have significant effect on characteristics of these granitoids. Based on strength tests studied rocks fall in category of moderately strong to strong. The values of specific gravity, porosity, water absorption and Los Angeles are within the range permissible for their use as constructional materials except SF. Based on physico-mechanical properties and petrographic examination Dubair-Shang granitoids could be used as aggregate for the construction of road, railway tracks, embankment, and canals. Theses rocks could also be used as sills, lentils, and roofing but should not be used for load bearing masonry like bridges, tunnels, buildings, dams","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66268280","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":"Experimental investigation on the point load strength of red-bed siltstone with different shapes","authors":"H. Yao","doi":"10.13168/agg.2020.0036","DOIUrl":"https://doi.org/10.13168/agg.2020.0036","url":null,"abstract":"The point load test is an indirect method to estimate the uniaxial compressive strength (UCS) of rock. In order to investigate the influence of the shape effect on the point load test strength of the siltstone in the Red Stratum, a series of point load tests were carried out on siltstone specimens with different shapes (cylinders, blocks, irregular specimens). The results show that the point load strength index of red-bed siltstone specimens with different shapes exhibits significant dispersion. As long as being corrected, the specimen shape has no significant effect on the point load strength index I s(50) . The average value of I s(50) from formula correction is consistent with the value obtained by the graphical method with all different shape specimens in consideration. An empirical relation is proposed for the estimation of UCS by the point load strength I S(50) . The red-bed siltstone specimens under the point load test are broken into two pieces or three pieces, but the former failure is dominant.","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44161400","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":"Analysis of position coordinate accuracy of triple GNSS system by post-processing dual frequency observations using open source GAMP: A case study","authors":"Jabir Shabbir Malik","doi":"10.13168/agg.2020.0035","DOIUrl":"https://doi.org/10.13168/agg.2020.0035","url":null,"abstract":"Multi GNSS system increases the GNSS positioning accuracy, efficiently improve the satellite geometry strength and further enhances precise point positioning (PPP) performance. In this study, positioning coordinate accuracy of GPS, GLONASS, Galileo and BeiDou dual frequency observations is estimated and comparatively analysed. Ten days of dataset from nine International GNSS service sites are adopted for eight different GNSS PPP scenarios. Position in east, north and up components and convergence speed test for single system GPS, GLONASS, BeiDou and Galileo, dual system GPS/GLONASS and Galileo/BeiDou, combined triple system GPS/GLONASS/BeiDou and GPS/GLONASS/Galileo is investigated. Results demonstrate that PPP solutions of GPS show an improvement in east, north and up components over GLONASS, BeiDou and Galileo PPP solutions. GPS PPP solutions reach to 2.88, 2.32 and 6.10 cm in east north and up components, respectively. Difference of standard deviation (STD) values between GPS and GLONASS PPP results is 4, 3 and 2 cm, in east, north and up direction, respectively. Moreover, difference of STD between GPS and Galileo PPP is >1cm in all three components. Furthermore, BeiDou only PPP results reach to 15, 10 and 20 cm in east, north and up direction in Asia Pacific, respectively. Horizontal component for combine Galileo/BeiDou PPP and GPS/GLONASS PPP solutions reach to 3.24 and 3.02 cm, respectively. Calculation results of 3D positioning show that combined GPS/GLONASS/BeiDou PPP solutions improve by 5.59 % and 17.72 % over GPS/GLONASS and Galileo/BeiDou PPP solutions, respectively. Furthermore, STD for 3D positioning of triple system GPS/GLONASS/Galileo shows an improvement of 47.53 %, 31.56 % and 24.90 % over Galileo/BeiDou, GPS/GLONASS and GPS/GLONASS/BeiDou PPP results, respectively. Two different convergence time tests are undertaken. Results of GPS-only PPP solutions show fastest convergence speed to achieve accuracy level of 1.0 cm over GLONASS-only, BeiDou-only, Galileo-only, and Galileo/BeiDou PPP solutions. Combine dual system GPS/GLONASS PPP convergence time show an improvement of 56.46 % over GPS-only solutions. The contribution of BeiDou to reducing the convergence time of the combine GPS/GLONASS PPP improve by 27.53 % over combine GPS/GLONASS PPP convergence time. Moreover, GPS/GLONASS/Galileo PPP convergence speed show an improvement of 20.06 % over convergent sessions of GPS/GLONASS/BeiDou PPP. Furthermore, to achieve accuracy level of 5.0 cm, combine three system GPS/GLONASS/BeiDou PPP reduces the convergence time than the GPS/GLONASS/Galileo convergent sessions length. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45360600","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":"Assessment of models to predict surface subsidence in the Czech part of the Upper Silesian Coal Basin - Case study","authors":"E. Jirankova","doi":"10.13168/agg.2020.0034","DOIUrl":"https://doi.org/10.13168/agg.2020.0034","url":null,"abstract":"This case study presents the verification of two surface subsidence prediction models for longwall mining at depths greater than 400 m. The surface subsidence points were surveyed and compared for both models. The first model uses empirical calculations to predict the surface subsidence. This method is reliable for predicting surface subsidence at shallower depths. At present, however, coal mining has progressed to great depths. The second model is the 2-dimensional finite element method to predict surface subsidence. In contrast to the first method, this method is based on the regional parameters and uses the rock mass properties to evaluate surface subsidence for multiseams at any depth. Results show that the finite element method gives a better approximation of the measured surface subsidence than the Knothe method. The maximum surface subsidence, which was determined by the FEM method, was used to adjust the extraction coefficient in the Knothe's method. The predicted value differs from the measured value by 8 %. The slope of the predicted subsidence trough was within the range of 2‒8 % from the surveyed subsidence. This case study proposes a procedure for using both models to successfully predict the surface subsidence. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"469-484"},"PeriodicalIF":0.9,"publicationDate":"2020-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49243732","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":"Application of rock mass classification to evaluate rock properties, NW Himalayas, Pakistan","authors":"M. Basharat","doi":"10.13168/agg.2020.0033","DOIUrl":"https://doi.org/10.13168/agg.2020.0033","url":null,"abstract":"The rock units of the NW Himalayan region are fragile, heavily fractured and highly deformed due to active tectonics and complex geological setup. Fast urbanization, road constructions along hill slopes and other infrastructural development activities also increased the slopes instability problems. The present study emphasizes the application of rock mass classification to estimate the rock mass properties along the Yadgar section Muzaffarabad, NW Himalayas, Pakistan. For this purpose, Rock Mass Rating (RMR) and Geological Strength Index (GSI) were used to characterize and classify the rock masses. In the present study, twenty-five sites have been investigated to evaluate rock properties along the Muzaffarabad-Neelum road, Sub-Himalayas, Pakistan. Result of the study shows that the Abbottabad Formation of Cambrian age is vulnerable in the Yadgar section with extremely poor RQD (Rock Quality Designation), lowest UCS (Unconfined Compression Strength) values and closely spaced discontinuities. RMR values of the Abbottabad Formation ranges from 40-54 and classified as Poor to Fair having low GSI (20±3-35±3), blocky, disintegrated structure. The Paleocene Hangu Formation has lowest GSI (28±3-29±3; Blocky, Disturbed/ Seamy in nature) having RMR (40-45) and Eocene Kuldana Formation has GSI (30±345±3; Blocky) having RMR (34-67), are categorized as heavily broken, disintegrated and poorly interlocked rock masses. RMR values of rock units of the Paleocene Lockhart Formation (52-60), the Miocene Murree Formation (38-63), and the Eocene Margala Hill Limestone (38-61) are relatively higher values of GSI ranges from (35±3-45±3; 35±3-50±3; 30±3-40±3) respectively. RMR and GSI values in Yadgar section, ranges between 34-67 and 20±3-50±3 respectively. Analysis shows positive correlation between GSI and RMR values. This approach to evaluate the rock mass classification through RMR and GSI will give the better estimation of rock mass properties along Muzaffarabad-Neelum road to identify the vulnerable slopes and design effective geotechnical measures. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"453-468"},"PeriodicalIF":0.9,"publicationDate":"2020-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47819496","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":"Automamatic detection of discontinuities in the station position time series of the reprocessed global GNSS network using Bernese GNSS Software","authors":"J. Najder","doi":"10.13168/agg.2020.0032","DOIUrl":"https://doi.org/10.13168/agg.2020.0032","url":null,"abstract":"For over 25 years, the International GNSS Service (IGS) has been processing observational data from the Global Navigation Satellite Systems (GNSSs). Hence, long time series of station coordinates are available, however, they are burdened with discontinuities, station velocity changes, and gross errors. Discontinuities and periodic variations are caused by equipment changes at stations, earthquakes, geophysical processes, data problems, as well as local environmental changes. As a result, many approaches have been identified that identify and remove discontinuities in the GNSS coordinate time series. One of them is the program Finding Outliers and Discontinuities In Time Series (FODITS) implemented in the Bernese GNSS Software environment (Dach et al., 2015), developed by the Astronomical Institute, University of Bern. The program is designed for the automatic analysis of time series, in which the functional model is adapted to the time series of coordinates depending on the adopted parameters. This study presents the analysis of long-term GNSS coordinate time series reprocessed in the framework of the realization of the International Terrestrial Reference Frame 2014 (ITRF2014) using the FODITS program. The results show that the optimum confidence level for the autonomous detection of station discontinuities in FODITS is 99 % and 98 %, for 7-day and 3-day GNSS solutions, respectively, when compared to the manual discontinuity detection from ITRF2014. However, the manual analysis unsupported by statistical tests as conducted in ITRF2014 may contain errors over which further elaboration is indispensable. On the other hand, routine interpretation of GNSS coordinate time series in a fully autonomous manner, although much faster, is not free from drawbacks, in particular in detecting appropriate epochs of discontinuities and changes in station velocities. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"17 1","pages":"439-451"},"PeriodicalIF":0.9,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43320256","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":"Performance comparison of least squares, iterative and global L1 norm minimization and exhaustive search methods for outlier detection in leveling networks","authors":"S. Baselga","doi":"10.13168/agg.2020.0031","DOIUrl":"https://doi.org/10.13168/agg.2020.0031","url":null,"abstract":"Different approaches have been proposed to determine the possible outliers existing in a dataset. The most widely used consists in the application of the data snooping test over the least squares adjustment results. This strategy is very likely to succeed for the case of zero or one outliers but, contrary to what is often assumed, the same is not valid for the multiple outlier case, even in its iterative application scheme. Robust estimation, computed by iteratively reweighted least squares or a global optimization method, is other alternative approach which often produces good results in the presence of outliers, as is the case of exhaustive search methods that explore elimination of every possible set of observations. General statements, having universal validity, about the best way to compute a geodetic network with multiple outliers are impossible to be given due to the many different factors involved (type of network, number and size of possible errors, available computational force, etc.). However, we see in this paper that some conclusions can be drawn for the case of a leveling network, which has a certain geometrical simplicity compared with planimetric or three-dimensional networks though a usually high number of unknowns and relatively low redundancy. Among other results, we experience the occasional failure in the iterative application of the data snooping test, the relatively successful results obtained by both methods computing the robust estimator, which perform equivalently in this case, and the successful application of the exhaustive search method, for different cases that become increasingly intractable as the number of outliers approaches half the number of degrees of freedom of the network. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"425-438"},"PeriodicalIF":0.9,"publicationDate":"2020-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48142456","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":"Tectonic crustal deformation of Corinth Gulf, Greece, based on primary geodetic data","authors":"Ilias Lazos","doi":"10.13168/agg.2020.0030","DOIUrl":"https://doi.org/10.13168/agg.2020.0030","url":null,"abstract":"The broader Corinth Gulf region is characterized by a notable active tectonic regime, associated with multiple active fault zones. The continuous N–S extensional tectonics of the area is responsible for the roughly E–W trending active normal fault zones, while individual fault segments are associated with seismic events. Satellite geodesy is a qualitative and quantitative means of estimating the tectonically active setting, based on the recorded motions. The study area is monitored by 14 permanent GPS/GNSS stations, collecting primary geodetic data for a 7-year time period (2008-2014). A 30-sec observation rate was performed, resulting in the extraction of the GPS/GNSS velocity values. The primary geodetic data were processed by applying the triangulation methodology, based on the combination of three different GPS/GNSS stations data, which were considered as the triangle vertices. Triangulation methodology led to the construction of 26 different triangles, while for each of them a series of parameters was determined. In particular, the extracted parameters are: a) Maximum Horizontal Extension, b) Total Velocity, c) Maximum Shear Strain and d) Area Strain. The extracted results are expected to approach, qualitatively and quantitatively, the interpretation of the tectonic regime, as well as to determine new, seismic-related, tectonic features. ARTICLE INFO","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"413-424"},"PeriodicalIF":0.9,"publicationDate":"2020-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46459701","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":"Nonlinear site response analysis by coupling scaled boundary finite element method and finite element method","authors":"Ali Barghi Kherzeloo","doi":"10.13168/agg.2020.0029","DOIUrl":"https://doi.org/10.13168/agg.2020.0029","url":null,"abstract":"This paper presented 2D numerical linear and nonlinear site response analyses based on the scaled boundary finite-element method (SBFEM) and compared their results with those of the DEEPSOIL software. In linear time-domain analysis, the seismic boundary traction was applied to lines in the near-field with the same vertical coordinates using seismic time history load. The far-field was modeled utilizing an improved continued-fraction-based high-order transmitting boundary. The constitutive relationship of the boundary was determined utilizing the SBFEM equation in the dynamic stiffness model. It was shown that the results of the SBFEM had a good agreement with those obtained from the DEEPSOIL software. The results of spectral acceleration demonstrated period lengthening. The nonlinear site responses were analyzed using both the DEEPSOIL software and the coupling of SBFEM/FEM. The one-dimensional nonlinear site response was analyzed using the tools in the DEEPSOIL software including the strength correction, pressure-dependent modulus reduction, and the damping ratio curve of sand. In the nonlinear-coupled analysis, the bounded domain was also modeled in OpenSees using a pressuredependent multi-yield plasticity soil model. The comparison of the results demonstrated the accuracy of the nonlinear analysis using the coupled SBFEM/FEM. The coupling method underestimated spectral acceleration in low periods compared with the DEEPSOIL software. The absolute residual was also obtained less than 0.2. ARTICLE INFO Article history: Received 25 May 2020 Accepted 31 August 2020 Available online 19 September 2020","PeriodicalId":50899,"journal":{"name":"Acta Geodynamica et Geomaterialia","volume":"1 1","pages":"397-412"},"PeriodicalIF":0.9,"publicationDate":"2020-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47258690","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}