VIETNAM JOURNAL OF EARTH SCIENCES最新文献_第9页

Pore water pressure responses of saturated sand and clay under undrained cyclic shearing 饱和砂土和粘土在不排水循环剪切作用下的孔隙水压力响应

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-12-01 DOI: 10.15625/2615-9783/16764

An, Hiroshi, Nhan, Tien, Thien

{"title":"Pore water pressure responses of saturated sand and clay under undrained cyclic shearing","authors":"An, Hiroshi, Nhan, Tien, Thien","doi":"10.15625/2615-9783/16764","DOIUrl":"https://doi.org/10.15625/2615-9783/16764","url":null,"abstract":"In this study, changes in the pore water pressure were observed for saturated specimens of a loose fined-grain sand (Nam O sand) and a soft silty clay (Hue clay) subjected to undrained cyclic shearing with different testing conditions. The cyclic shear tests were run for relatively wide range of shear strain amplitude (g = 0.05%-2%), different cycle numbers (n = 10, 50, 150 and 200) and various shear directions (uni-direction and two-direction with phase difference of q = 0o, 45o and 90o). It is indicated from the experimental results that under the same cyclic shearing condition, the pore water pressure accumulation in Hue clay is at a slower rate, suggesting a higher cyclic shear resistance of Hue clay than that of Nam O sand. Liquefaction is reached easily in nominally 50% relative density specimens of Nam O sand when g ³ 0.4%, meanwhile soft specimen of Hue clay is not liquefied regardless of the cyclic shearing conditions used in this study. The threshold number of cycles for the pore water pressure generation generally decreases with g meanwhile, the threshold cumulative shear strain for such a property mostly approaches 0.1%. In addition, by using this new strain path parameter, it becomes more advantageous when evaluating the pore water pressure accumulation in Nam O sand and Hue clay subjected to undrained uni-directional and two-directional cyclic shears.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44330323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Determination of actual characteristic curve of main ventilation fan at Quang Ninh underground coal mines using field measurement method 广宁地下煤矿主通风机实际特性曲线的现场测量测定

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-11-30 DOI: 10.15625/2615-9783/16761

Dao Van Chi, Dung Le Tien, Xuan Ha Tran

{"title":"Determination of actual characteristic curve of main ventilation fan at Quang Ninh underground coal mines using field measurement method","authors":"Dao Van Chi, Dung Le Tien, Xuan Ha Tran","doi":"10.15625/2615-9783/16761","DOIUrl":"https://doi.org/10.15625/2615-9783/16761","url":null,"abstract":"Determining a proper operation mode of the main ventilation fan at an underground coal mine primarily uses the theoretical characteristic curves of the fan’s manufacturer. Because these curves are developed in laboratory-standard conditions, the characteristic curves under different conditions in practice significantly change, seriously impacting the ventilation efficiency and environmental safety of mine. This paper presents a determination of the main fan's actual characteristic curve using a field measurement method. The method involves the (i) simultaneous measurement of airflow and air pressure at designated locations in fan drift and ventilation crosscut and (ii) statistical analysis and interpolation of the measured data. The results show that the fan actual pressure curve is permanently displaced to the left and steeper than the corresponding theoretical pressure curve in an on-site operating mode. The finding points out that on-site fans operate in overload mode that can quickly damage their mechanical components. This method provides mining engineers with an easy-to-apply tool for proper adjustment of the operation mode. This improves ventilation efficiency, increases environmental safety, and reduces the underground coal mine operational costs.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42075737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Flood susceptibility modeling using Radial Basis Function Classifier and Fisher’s linear discriminant function 基于径向基函数分类器和Fisher线性判别函数的洪水敏感性建模

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-10-12 DOI: 10.15625/2615-9783/16626

Chinh Luu, Duc Dam Nguyen, M. Amiri, Phong Tran Van, Quynh Duy Bui, Indra Prakash, Binh Thai Pham

{"title":"Flood susceptibility modeling using Radial Basis Function Classifier and Fisher’s linear discriminant function","authors":"Chinh Luu, Duc Dam Nguyen, M. Amiri, Phong Tran Van, Quynh Duy Bui, Indra Prakash, Binh Thai Pham","doi":"10.15625/2615-9783/16626","DOIUrl":"https://doi.org/10.15625/2615-9783/16626","url":null,"abstract":"Floods are among the most frequent highly disastrous hazards affecting life, property, and the environment worldwide. While various models are available to predict flood susceptibility, no model is accurate enough to be used for all flood-prone areas. Model development using different algorithms is a continuous process to improve the prediction accuracy of flood susceptibility. In the study, we used the Radial Basis Function and Fisher’s linear discriminant function to develop a flood susceptibility map for a case study of Quang Binh Province. The model development used ten variables (elevation, slope, curvature, river density, distance from river, geomorphology, land use, flow accumulation, flow direction, and rainfall). For model training and validation, input data was split into a 70:30 ratio according to flood locations. Statistical indexes were used to evaluate model performance such as Receiver Operating Characteristic, the Area Under the ROC Curve, Root Mean Square Error, Accuracy, Sensitivity, Specificity, and Kappa index. Results indicated that the radial basis function classifier model had better performance in predicting flood susceptible areas based on the statistical measures (PPV = 92.00%, NPV = 87.00%, SST = 87.62%, SPF = 91.58%, ACC = 89.50%, Kappa = 0.790, MAE = 0.204, RMSE = 0.292 and AUC = 0.957. Therefore, the radial basis function classifier algorithm model is appropriate for predicting flood susceptibility in Quang Binh Province.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46274568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Evaluation of the Global Satellite Mapping of Precipitation (GSMaP) data on sub-daily rainfall patterns in Vietnam 全球卫星降水测绘（GSMaP）数据对越南亚日降雨模式的评估

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-10-02 DOI: 10.15625/2615-9783/16594

Hoa Pham, J. Matsumoto, M. I. Nodzu

{"title":"Evaluation of the Global Satellite Mapping of Precipitation (GSMaP) data on sub-daily rainfall patterns in Vietnam","authors":"Hoa Pham, J. Matsumoto, M. I. Nodzu","doi":"10.15625/2615-9783/16594","DOIUrl":"https://doi.org/10.15625/2615-9783/16594","url":null,"abstract":"This study aims to evaluate the performance of Global Satellite Mapping of Precipitation (GSMaP) data in observing the sub-daily rainfall patterns in Vietnam using synoptic gauge measurements considering seasonal variations in rainfall. Differences in the estimations of the three GSMaP products, including the standard version 7 (MVKv7) and two gauge-calibrated versions 6 and 7 (GAUv6 and GAUv7), were clarified based on rainfall characteristic parameters and statistical indices. The present study clarified that the contribution of sub-daily rainfall in Vietnam was higher during the afternoon than at other times, predominantly in the Central Highlands and Southern Plain, while it occurred most often during the evening to early morning in northern regions. Distinct regional features were also identified along the central coast. Most of the summer afternoon maximum fell in the western mountainous area, while the eastern coastal plain experienced an insignificant amount of rainfall. As rainfall characteristics varied with seasons and regions, the performance of GSMaP demonstrated this variation quite well compared to in-situ observations. However, GSMaP still exhibited high biases in rainy season and topographically heterogeneous areas, especially in the northern regions where sub-daily rainfall cycles had large variations. The standard GSMaP (MVK) product illustrated an afternoon peak better than the gauge-calibrated (GAU) product, which suggests that utilizing the MVK in the Central Highlands and Southern Plain and the GAU over central coastal regions would be appropriate when considering the characteristics of sub-daily precipitation.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49397465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Assessment and reduction of zenith path delay biases due to day boundary effect 天边界效应引起的天顶路径延迟偏差的评估和减少

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-09-30 DOI: 10.15625/2615-9783/16587

Lau Nguyen Ngoc, R. Coleman

引用次数: 1

Geochemistry and mineralogy of the Truc Thon Clay, Hai Duong Province, North Vietnam: implication for paleoclimatic and provenance analysis 越南北部海阳省Truc Thon粘土的地球化学和矿物学：对古气候和物源分析的意义

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-09-22 DOI: 10.15625/2615-9783/16572

T. H. Van, S. Iqbal, Urszula Czarniecka, A. Wysocka, Pha Phan Dong, Cuong Nguyen Quoc, Ha Vu Van, Tuan Dang Minh

{"title":"Geochemistry and mineralogy of the Truc Thon Clay, Hai Duong Province, North Vietnam: implication for paleoclimatic and provenance analysis","authors":"T. H. Van, S. Iqbal, Urszula Czarniecka, A. Wysocka, Pha Phan Dong, Cuong Nguyen Quoc, Ha Vu Van, Tuan Dang Minh","doi":"10.15625/2615-9783/16572","DOIUrl":"https://doi.org/10.15625/2615-9783/16572","url":null,"abstract":"During the Miocene-Pleistocene, generally sub-tropical to tropical warm and humid paleoclimate prevailed in Southeast Asia with a gradual cooling trend. The Truc Thon clay (TTC) mine presents interesting outcrops for sedimentological and provenance analysis. The present study uses results of geological investigation in 16 outcrops and wells at the clay mine Truc Thon. The TTC has lens-shaped geometry, filled with two clay bodies, including grey-white clay and multicolor clay. Bulk mineralogy indicates the predominance of quartz and a relatively high amount of pyrophyllite. Clay mineralogy shows the presence of main kaolinite, followed by illite and mixed-layer illite-smectite. These may interpret a warm, humid paleoclimatic condition in the source areas. Illite may be inherited from basement rocks. The bulk rock geochemistry supports intense chemical weathering with the Chemical Index of Alteration (CIA) in the TTC ranged ca. 80.6-98 (average = 90.4). In combination with the geochemical proxies and the mineralogical composition of the TTC, the chemical weathering intensity indicated warm/hot, semi-humid/humid tropical paleoclimate in the source area. A combination of mineralogical and geochemical analyses with regional geological features show that the Hon Gai Triassic rocks are the main source for the TTC. Source materials are originally related to silicic rocks of granitic-granodioritic composition. Paleoclimatic conditions favored intense chemical weathering of the Hon Gai Triassic rocks and surrounding rocks, creating a ceramic mine of great industrial value.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48251008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Chemical, mineralogical, and physicochemical features of surface saline muds from Southwestern sub-basin of the East Vietnam Sea: Implication for new peloids 东越海西南亚盆地表层含盐泥浆的化学、矿物学和物理化学特征：对新类球粒的意义

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-09-17 DOI: 10.15625/2615-9783/16561

Luong Le Duc, H. Nguyen, R. Shinjo, Renat B. Shakirov, A. Obzhirov

{"title":"Chemical, mineralogical, and physicochemical features of surface saline muds from Southwestern sub-basin of the East Vietnam Sea: Implication for new peloids","authors":"Luong Le Duc, H. Nguyen, R. Shinjo, Renat B. Shakirov, A. Obzhirov","doi":"10.15625/2615-9783/16561","DOIUrl":"https://doi.org/10.15625/2615-9783/16561","url":null,"abstract":"This study presents the chemical, mineralogical and physicochemical features of 8 saline mud samples from 8 gravity cores located in the southwestern sub-basin of the East Vietnam Sea. The grain-size analysis of mud samples reveals the amount of clay and silt particles in the ranges of 65.1-89.2% and 9.5-34.2%, respectively and a very low fraction of sand. The analytical results showed that mud samples have high contents of SiO2 (32.79-48.09%), Al2O3 (11.26-13.63%), CaO (3.10-13.93%), Fe2O3 (4.15-9.45%), and low contents of TiO2, MnO, MgO, Na2O, K2O and P2O5. The XRD analysis of mud samples indicated mineral compositions with major minerals of quartz, illite, calcite, chlorite, feldspar, kaolinite, and other minor minerals like halite, smectite, fluorapatite, pyroxene, amphibole. The organic and physicochemical parameters of mud samples were also measured. Potentially toxic elements in mud samples were determined and compared with reference values and the technical standard. This study proposes that saline mud samples from the studied area are potential peloids.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46266299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Assessing trophic status of Suoi Hai Reservoir using Carlson’s Trophic State Index 利用卡尔森营养状态指数评价索海水库的营养状况

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-09-17 DOI: 10.15625/2615-9783/16562

Linh Nguyen Thuy, Ha Nguyen Thi Thu, Thao Nguyen Thien Phuong, Vinh Pham Quang

{"title":"Assessing trophic status of Suoi Hai Reservoir using Carlson’s Trophic State Index","authors":"Linh Nguyen Thuy, Ha Nguyen Thi Thu, Thao Nguyen Thien Phuong, Vinh Pham Quang","doi":"10.15625/2615-9783/16562","DOIUrl":"https://doi.org/10.15625/2615-9783/16562","url":null,"abstract":"The water quality of Suoi Hai reservoir, the largest reservoir in Hanoi city, is being threatened by human activities of the surrounding area, as reported by the press. The trophic status of the reservoir is the result of both natural eutrophication and nutrient inputs from anthropogenic sources, particularly the leachate from a lakeside waste treatment plant. This study aims to identify the trophic status of the Suoi Hai reservoir and the changes of water trophic state over space and time. Data of chlorophyll-a concentration, total phosphorus, and Secchi disk depth from 51 sites during three field campaigns in October 2019, August 2020, and March 2021 was used to calculate Carlson’s trophic state index (CTSI). Resultant CTSI (ranged from 60 to 72) allows classifying Suoi Hai reservoir as highly eutrophic water. Its variations in space and time provided evidence for an influence of anthropogenic activities on the reservoir trophic state. Analysis of the trophic state index deviations suggested that total phosphorus is the key factor that influenced the reservoir trophic state. Therefore, managing the anthropogenic nutrient inputs load to the reservoir should be a critical task to control eutrophication in Suoi Hai Reservoir at present. ","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46012748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Characterization of ionospheric irregularities over Vietnam and adjacent region for the 2008-2018 period 2008-2018年越南及其邻近地区电离层不规则性特征

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-08-30 DOI: 10.15625/2615-9783/16502

Dung Nguyen Thanh, M. Huy, C. Amory-Mazaudier, R. Fleury, S. Saito, Thang Nguyen Chien, H. P. Thu, T. L. Truong, Mai Nguyen Thi

{"title":"Characterization of ionospheric irregularities over Vietnam and adjacent region for the 2008-2018 period","authors":"Dung Nguyen Thanh, M. Huy, C. Amory-Mazaudier, R. Fleury, S. Saito, Thang Nguyen Chien, H. P. Thu, T. L. Truong, Mai Nguyen Thi","doi":"10.15625/2615-9783/16502","DOIUrl":"https://doi.org/10.15625/2615-9783/16502","url":null,"abstract":"This paper presents the variations of the rate of change of Total Electron Content (TEC) index (ROTI), characterizing the occurrence of ionospheric plasma irregularities over Vietnam and neighboring countries in the Southeast Asian region using the continuous GPS data during the 2008-2018 period. The results showed that the occurrence of strong ROTI in all stations is maximum in equinox months March/April and September/October and depends on solar activity. The ROTI is weak during periods of low solar activity and strong during periods of high solar activity. There is an asymmetry between the two equinoxes. During maximum and declining phases of 2014-2016, occurrence rates in March equinox are larger than in September equinox, but during the descending period of 2010-2011, the occurrence rates in September equinox at almost all stations are larger than in March equinox. The correlation coefficients between the monthly occurrence rate of irregularities and the F10.7 solar index at the stations in the equatorward EIA crest region are higher than at those in the magnetic equatorial and the poleward EIA crest regions. The irregularity occurrence is high in the pre-midnight sector, maximum between 2000 LT to 2200 LT. The maximum irregularity occurrence is located around 4-5° degrees in latitude equator-ward away from the anomaly crests.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42059947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Paleogene granite magmatism in the north of the Truong Son belt and implication for crustal evolution Truong Son带北部古近系花岗岩岩浆作用及其对地壳演化的意义

IF 1.5

VIETNAM JOURNAL OF EARTH SCIENCES Pub Date : 2021-08-19 DOI: 10.15625/2615-9783/16444

Huan Trinh Dinh, Tri Luu Cong, A. Tuan, Anh Tran Viet, Giang Phan Hoang, Takahashi, Saadsy

引用次数: 4