Pub Date : 2021-08-19DOI: 10.15625/2615-9783/16442
Anh Do Ngoc, D. Dias, Thang Trong Dang
Three-dimensional finite difference calculations are proposed to investigate the influence of operation parameters of the shield machines during twin stacked tunnel excavation on the surface settlements. The numerical model is validated by experimental data obtained from Hochiminh’s metro line 1 project, used as a reference case in this study. The parametric study focuses on the influence of the face support pressure, the grouting pressure, and the shield’s length. The numerical results indicated that a decrease does not always follow an increase in surface settlements' face and grouting pressure. A shorter shield machine causes smaller surface settlements to develop over single lower and twin stacked tunnels.
{"title":"A numerical investigation of the impact of shield machine’s operation parameters on the settlements above twin stacked tunnels - A case study of Ho Chi Minh urban railway Line 1","authors":"Anh Do Ngoc, D. Dias, Thang Trong Dang","doi":"10.15625/2615-9783/16442","DOIUrl":"https://doi.org/10.15625/2615-9783/16442","url":null,"abstract":"Three-dimensional finite difference calculations are proposed to investigate the influence of operation parameters of the shield machines during twin stacked tunnel excavation on the surface settlements. The numerical model is validated by experimental data obtained from Hochiminh’s metro line 1 project, used as a reference case in this study. The parametric study focuses on the influence of the face support pressure, the grouting pressure, and the shield’s length. The numerical results indicated that a decrease does not always follow an increase in surface settlements' face and grouting pressure. A shorter shield machine causes smaller surface settlements to develop over single lower and twin stacked tunnels.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43113262","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}
Pub Date : 2021-08-19DOI: 10.15625/2615-9783/16440
T. T. Thanh, Liem Nguyen Duy, Luu Pham Thanh, Y. My, Yen Tran Thi Hoang, Quang Ngo Xuan, Tan Lam Van, Hoai Pham Ngoc
The Mekong Delta is the most severely affected area by saltwater intrusion in Vietnam. Recent studies have focused on predicting this disaster with weekly and decade lead times without many seasonal forecasts, which is important for planning crop selection, crop structure, and sowing time. This study aims to forecast the spatial distribution of saltwater intrusion into the Mekong river estuaries of Vietnam during the dry season of 2021 by integrating Auto-Regressive Integrated Moving Average with Geographic Information System. ARIMA models were trained with a single input of water salinity measurements from 2012 to 2020. Compared to the weekly salinity observations in 2021, these models predicted very well in the My Tho and Ham Luong rivers but unsatisfactory performance in the Co Chien river. The deepest saltwater intrusion will occur between March 19th and April 16th of 2021, when the 4‰ saline front will move the farthest distance of 41,41 and 44 kilometers inland from the sea through My Tho, Ham Luong Co Chien rivers, respectively. The entire river system will be exposed to moderate risk of saltwater intrusion. Freshwater zones decreased significantly to 0.73% of the whole area of Ben Tre province. These findings could provide a valuable scientific foundation for the appropriate management of coastal aquifers to control or reduce saltwater intrusion.
湄公河三角洲是越南受海水入侵影响最严重的地区。最近的研究主要集中在预测每周和十年的提前期，而没有许多季节性预测，这对规划作物选择，作物结构和播种时间很重要。采用自回归综合移动平均和地理信息系统相结合的方法，预测2021年越南湄公河河口干旱期海水入侵的空间分布。ARIMA模型使用2012年至2020年的单一盐度测量输入进行训练。与2021年的每周盐度观测结果相比，这些模型对美苴河和咸隆河的预测非常好，但对Co Chien河的预测却不尽如人意。最深的盐水入侵将发生在2021年3月19日至4月16日之间，届时4‰的盐水锋将分别通过My Tho, Ham Luong Co Chien河从海洋向内陆移动最远的距离为41,41和44公里。整个河流系统将面临中等程度的盐水入侵风险。淡水区面积显著减少，仅占本省总面积的0.73%。这些发现可为适当管理沿海含水层以控制或减少盐水入侵提供有价值的科学依据。
{"title":"Performance evaluation of Auto-Regressive Integrated Moving Average models for forecasting saltwater intrusion into Mekong river estuaries of Vietnam","authors":"T. T. Thanh, Liem Nguyen Duy, Luu Pham Thanh, Y. My, Yen Tran Thi Hoang, Quang Ngo Xuan, Tan Lam Van, Hoai Pham Ngoc","doi":"10.15625/2615-9783/16440","DOIUrl":"https://doi.org/10.15625/2615-9783/16440","url":null,"abstract":"The Mekong Delta is the most severely affected area by saltwater intrusion in Vietnam. Recent studies have focused on predicting this disaster with weekly and decade lead times without many seasonal forecasts, which is important for planning crop selection, crop structure, and sowing time. This study aims to forecast the spatial distribution of saltwater intrusion into the Mekong river estuaries of Vietnam during the dry season of 2021 by integrating Auto-Regressive Integrated Moving Average with Geographic Information System. ARIMA models were trained with a single input of water salinity measurements from 2012 to 2020. Compared to the weekly salinity observations in 2021, these models predicted very well in the My Tho and Ham Luong rivers but unsatisfactory performance in the Co Chien river. The deepest saltwater intrusion will occur between March 19th and April 16th of 2021, when the 4‰ saline front will move the farthest distance of 41,41 and 44 kilometers inland from the sea through My Tho, Ham Luong Co Chien rivers, respectively. The entire river system will be exposed to moderate risk of saltwater intrusion. Freshwater zones decreased significantly to 0.73% of the whole area of Ben Tre province. These findings could provide a valuable scientific foundation for the appropriate management of coastal aquifers to control or reduce saltwater intrusion.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42441375","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}
Pub Date : 2021-07-30DOI: 10.15625/2615-9783/16328
E. Brandmayr, V. Franco, Romanelli Fabio, V. Gordana, Panza Giuliano Francesco
Kosovo is one of the most seismically active regions in Europe, lying within the Alpine-Mediterranean tectonic belt. Historical records for the region show several catastrophic earthquakes with epicentral intensity IX (MCS). However, due to Kosovo’s high population density, high prevalence of traditional construction, and insufficient enforcement of building codes, Kosovo is vulnerable to earthquake damage. In this study, we present earthquake hazard maps for bedrock conditions in Kosovo based on the well-known Neo-deterministic Seismic Hazard Assessment (NDSHA) method. NDSHA relies upon the fundamental physics of wave generation and propagation in complex geologic structures to generate realistic time series, used as input for the computation of several ground motion parameters, integrating the available knowledge of seismic history, seismogenic zones and morphostructural nodes. In accordance with continuum mechanics, the tensor nature of earthquake ground motion is preserved, producing realistic signals using structural models obtained by tomographic inversion and earthquake source information readily available in literature. Our maps are generally consistent with the observed intensity IX (MCS) and suggest that, in some instances, intensity X could be reached.
{"title":"Neo-deterministic seismic hazard maps of Kosovo","authors":"E. Brandmayr, V. Franco, Romanelli Fabio, V. Gordana, Panza Giuliano Francesco","doi":"10.15625/2615-9783/16328","DOIUrl":"https://doi.org/10.15625/2615-9783/16328","url":null,"abstract":"Kosovo is one of the most seismically active regions in Europe, lying within the Alpine-Mediterranean tectonic belt. Historical records for the region show several catastrophic earthquakes with epicentral intensity IX (MCS). However, due to Kosovo’s high population density, high prevalence of traditional construction, and insufficient enforcement of building codes, Kosovo is vulnerable to earthquake damage. In this study, we present earthquake hazard maps for bedrock conditions in Kosovo based on the well-known Neo-deterministic Seismic Hazard Assessment (NDSHA) method. NDSHA relies upon the fundamental physics of wave generation and propagation in complex geologic structures to generate realistic time series, used as input for the computation of several ground motion parameters, integrating the available knowledge of seismic history, seismogenic zones and morphostructural nodes. In accordance with continuum mechanics, the tensor nature of earthquake ground motion is preserved, producing realistic signals using structural models obtained by tomographic inversion and earthquake source information readily available in literature. Our maps are generally consistent with the observed intensity IX (MCS) and suggest that, in some instances, intensity X could be reached.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49240420","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}
Pub Date : 2021-07-23DOI: 10.15625/2615-9783/16315
Binh Pham Duc, Son Tong Si
For the first time, this study estimates the variation of surface water extent of Nui Coc Lake located in Thai Nguyen province in North Vietnam at high spatial (20 m) and temporal resolution (bi-weekly). The classification methodology was developed based on the use of the Otsu threshold algorithm on the histogram of the backscatter coefficient of the SAR Sentinel-1 signal. Totally, more than 150 SAR Sentinel-1 images have been processed for the 2016-2020 period. Except for extreme drought and flood conditions, the average minimum and maximum of the lake’s surface water extent are 17 km2 (in May) and 24 km2 (in September/October), respectively, and Nui Coc Lake’s surface water was stable during the last five years. Classification results are in good agreement with the corresponding surface water extent maps derived from free-cloud Sentinel-2 images, with the occurrence map derived from the Landsat-derived Global Surface Water (GSW) product, and with in situ precipitation data. Compared to Sentinel-2, the lake’s surface water extent detected from Sentinel-1 is 4-4.5% less. The water occurrence is similar between our results and that derived from the GSW product, but Sentinel-1 data provide more details as its spatial resolution is higher than Landsat. This study clearly shows the great potential of SAR Sentinel-1 data for monitoring small lake’s water surface at low costs, especially over tropical regions.
{"title":"Monitoring spatial-temporal dynamics of small lakes based on SAR Sentinel-1 observations: a case study over Nui Coc Lake (Vietnam)","authors":"Binh Pham Duc, Son Tong Si","doi":"10.15625/2615-9783/16315","DOIUrl":"https://doi.org/10.15625/2615-9783/16315","url":null,"abstract":"For the first time, this study estimates the variation of surface water extent of Nui Coc Lake located in Thai Nguyen province in North Vietnam at high spatial (20 m) and temporal resolution (bi-weekly). The classification methodology was developed based on the use of the Otsu threshold algorithm on the histogram of the backscatter coefficient of the SAR Sentinel-1 signal. Totally, more than 150 SAR Sentinel-1 images have been processed for the 2016-2020 period. Except for extreme drought and flood conditions, the average minimum and maximum of the lake’s surface water extent are 17 km2 (in May) and 24 km2 (in September/October), respectively, and Nui Coc Lake’s surface water was stable during the last five years. Classification results are in good agreement with the corresponding surface water extent maps derived from free-cloud Sentinel-2 images, with the occurrence map derived from the Landsat-derived Global Surface Water (GSW) product, and with in situ precipitation data. Compared to Sentinel-2, the lake’s surface water extent detected from Sentinel-1 is 4-4.5% less. The water occurrence is similar between our results and that derived from the GSW product, but Sentinel-1 data provide more details as its spatial resolution is higher than Landsat. This study clearly shows the great potential of SAR Sentinel-1 data for monitoring small lake’s water surface at low costs, especially over tropical regions.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49272286","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}
Pub Date : 2021-07-22DOI: 10.15625/2615-9783/16313
Can Trong Nguyen, Diep Nguyen Thi Hong, Iabchoon Sanwit
The Eastern Economic Corridor project (EEC), which spans over three coastal provinces east of the Bangkok Metropolitan Area (BMA), aims to transform Thailand into a developed country progressively. The EEC project promises to influence its territory and surrounding areas. We aimed to monitor the urbanized directions at the BMA during 2015-2017 and explore whether the BMA’s urban expansion trend is related to the EEC. The results revealed that the built-up areas increased by 24,033 hectares (22.8%). The urban districts with high urban density slowly developed, while the rural districts tended to urbanize with a high urbanization rate, approximately 6.8% per year. The BMA urban areas mainly expanded to the east (14.9% per year) and southeast (21.6% per year) under partial impacts from the EEC infrastructure projects. The research findings represent a concept for assessing urban expansion and pointing to the regions of concern, which will be meaningful for urban planning and policymaking.
{"title":"Direction of urban expansion in the Bangkok Metropolitan Area, Thailand under the impacts of a national strategy","authors":"Can Trong Nguyen, Diep Nguyen Thi Hong, Iabchoon Sanwit","doi":"10.15625/2615-9783/16313","DOIUrl":"https://doi.org/10.15625/2615-9783/16313","url":null,"abstract":"The Eastern Economic Corridor project (EEC), which spans over three coastal provinces east of the Bangkok Metropolitan Area (BMA), aims to transform Thailand into a developed country progressively. The EEC project promises to influence its territory and surrounding areas. We aimed to monitor the urbanized directions at the BMA during 2015-2017 and explore whether the BMA’s urban expansion trend is related to the EEC. The results revealed that the built-up areas increased by 24,033 hectares (22.8%). The urban districts with high urban density slowly developed, while the rural districts tended to urbanize with a high urbanization rate, approximately 6.8% per year. The BMA urban areas mainly expanded to the east (14.9% per year) and southeast (21.6% per year) under partial impacts from the EEC infrastructure projects. The research findings represent a concept for assessing urban expansion and pointing to the regions of concern, which will be meaningful for urban planning and policymaking.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45667706","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}
Pub Date : 2021-07-09DOI: 10.15625/2615-9783/16268
L. H. Van, T. N. Tien, Tuan Vu Tat, T. Thanh, Anh Nguyen Lam, Din Dao Bui, D. L. Van, Dien Tran Ngoc, Hiep Nguyen Huu
Offshore Southeast (SE) Vietnam is considered a transition zone, with the sedimentary evolution of this area controlled by land-sea interactions, especially by the Holocene sea-level rise. This study presents some new findings regarding Holocene sedimentation and its linkage to the heavy mineral placers within the study area based on high-resolution seismic interpretation and sediment analysis. Our obtained results show that the Holocene sediments directly overlie the Late Pleistocene sedimentary formation, from which they are separated by an erosional/unconformity surface (R1 seismic reflector). Sediments deposited in the Early (~11.7-8.2kyr BP), Middle-Late (8.2kyr BP-present-day) Holocene sub-epochs correspond to the Transgressive and Highstand System tracts, which were closely controlled by the three stages of Holocene sea-level rise. The recent sediments distributed on the seafloor are dominated by sand and gravelly sand, demonstrating high-energy conditions, while the heavy minerals are rich in ilmenite and zircon. Most of these are concentrated along the present shoreline zones, but we do not exclude their accumulation in the paleo-shoreline and incised channels. Two ilmenite dispersion halos (1st and 2nd order) and one zircon dispersion halo (1st order) suggest that ilmenite and zircon are the most dominant heavy minerals while gold is only observed locally. The minerals were potentially derived from the weathering products of the Triassic-Cretaceous ilmenite-, zircon-, and gold-bearing granite and granitoid in central Vietnam.
越南东南近海被认为是一个过渡带，该地区的沉积演化受陆海相互作用的控制，特别是受全新世海平面上升的控制。本文在高分辨率地震解释和沉积物分析的基础上，提出了研究区内全新世沉积及其与重矿物砂矿的联系的一些新发现。研究结果表明，全新世沉积物直接覆盖在晚更新世沉积组上，由一个侵蚀/不整合面(R-1 -地震反射面)隔开。全新世早(~11.7 ~ 8.2kyr BP)、中晚(8.2kyr BP ~今)亚世沉积对应海侵体系域和高地体系域，受全新世海平面上升三个阶段的密切控制。近期海底分布的沉积物以砂和砾石砂为主，表现出高能环境，重矿物以钛铁矿和锆石为主。它们大部分集中在现今的岸线带，但不排除它们在古岸线和切割河道中聚集。两个钛铁矿弥散晕(一级和二级)和一个锆石弥散晕(一级)表明钛铁矿和锆石是最主要的重矿物，而金仅在局部可见。这些矿物可能来源于越南中部三叠系-白垩系钛铁矿、锆石和含金花岗岩和花岗岩类的风化产物。
{"title":"Holocene sedimentation offshore Southeast Vietnam based on geophysical interpretation and sediment composition analysis","authors":"L. H. Van, T. N. Tien, Tuan Vu Tat, T. Thanh, Anh Nguyen Lam, Din Dao Bui, D. L. Van, Dien Tran Ngoc, Hiep Nguyen Huu","doi":"10.15625/2615-9783/16268","DOIUrl":"https://doi.org/10.15625/2615-9783/16268","url":null,"abstract":"Offshore Southeast (SE) Vietnam is considered a transition zone, with the sedimentary evolution of this area controlled by land-sea interactions, especially by the Holocene sea-level rise. This study presents some new findings regarding Holocene sedimentation and its linkage to the heavy mineral placers within the study area based on high-resolution seismic interpretation and sediment analysis. Our obtained results show that the Holocene sediments directly overlie the Late Pleistocene sedimentary formation, from which they are separated by an erosional/unconformity surface (R1 seismic reflector). Sediments deposited in the Early (~11.7-8.2kyr BP), Middle-Late (8.2kyr BP-present-day) Holocene sub-epochs correspond to the Transgressive and Highstand System tracts, which were closely controlled by the three stages of Holocene sea-level rise. The recent sediments distributed on the seafloor are dominated by sand and gravelly sand, demonstrating high-energy conditions, while the heavy minerals are rich in ilmenite and zircon. Most of these are concentrated along the present shoreline zones, but we do not exclude their accumulation in the paleo-shoreline and incised channels. Two ilmenite dispersion halos (1st and 2nd order) and one zircon dispersion halo (1st order) suggest that ilmenite and zircon are the most dominant heavy minerals while gold is only observed locally. The minerals were potentially derived from the weathering products of the Triassic-Cretaceous ilmenite-, zircon-, and gold-bearing granite and granitoid in central Vietnam.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43709599","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}
Pub Date : 2021-06-25DOI: 10.15625/2615-9783/16204
Lan Tran Thi, Duong Nguyen Anh, Anh Phan Luu, Man Tran Thi
Fly ash is a waste byproduct of thermal power plants or steel plants with a low density. Study on using fly ash to produce lightweight construction materials will is a new application of this material resource. Pha Lai fly ash is a byproduct from Pha Lai Thermal Power Joint Stock Company, in which the main mineral component was mullite (15-20%), quartz (14-16%), carbon (5-7%). The content of the amorphous component was about 67-73%. The chemical composition of Pha Lai mainly was SiO2 (51.73%), Al2O3 (23.22%), Fe2O3 (4.23%). To fabricate the lightweight material from Pha Lai fly ash, the fly ash was mixed with additive materials to create binders following two ways: (1) lime + fly ash and (2) geopolymer technology. For the way of lime + fly ash, with the optimal mixture ratio was fly ash:lime: water = 10:2:1, the lightweight material samples had the bulk density of 1.32g/cm3, the compressive strength of 3.91 MPa, satisfied the Vietnamese standard TCVN 6477-2011 for concrete bricks. Applying the geopolymer technology, with the optimal mixture ratio was fly ash: NaOH/Na2SiO3: Al powder = 100:45:0.15, NaOH/Na2SiO3 ratio = 1:2, the lightweight materials obtained the bulk density of 0,62g/cm3, the compressive strength of 1,54 MPa, satisfied the Vietnamese standard TCVN:9029-2017 for Lightweight concrete - Foam concrete and non-autoclaved concrete products-specification.
{"title":"Use fly ash for the production of lightweight building materials","authors":"Lan Tran Thi, Duong Nguyen Anh, Anh Phan Luu, Man Tran Thi","doi":"10.15625/2615-9783/16204","DOIUrl":"https://doi.org/10.15625/2615-9783/16204","url":null,"abstract":"Fly ash is a waste byproduct of thermal power plants or steel plants with a low density. Study on using fly ash to produce lightweight construction materials will is a new application of this material resource. Pha Lai fly ash is a byproduct from Pha Lai Thermal Power Joint Stock Company, in which the main mineral component was mullite (15-20%), quartz (14-16%), carbon (5-7%). The content of the amorphous component was about 67-73%. The chemical composition of Pha Lai mainly was SiO2 (51.73%), Al2O3 (23.22%), Fe2O3 (4.23%). To fabricate the lightweight material from Pha Lai fly ash, the fly ash was mixed with additive materials to create binders following two ways: (1) lime + fly ash and (2) geopolymer technology. For the way of lime + fly ash, with the optimal mixture ratio was fly ash:lime: water = 10:2:1, the lightweight material samples had the bulk density of 1.32g/cm3, the compressive strength of 3.91 MPa, satisfied the Vietnamese standard TCVN 6477-2011 for concrete bricks. Applying the geopolymer technology, with the optimal mixture ratio was fly ash: NaOH/Na2SiO3: Al powder = 100:45:0.15, NaOH/Na2SiO3 ratio = 1:2, the lightweight materials obtained the bulk density of 0,62g/cm3, the compressive strength of 1,54 MPa, satisfied the Vietnamese standard TCVN:9029-2017 for Lightweight concrete - Foam concrete and non-autoclaved concrete products-specification.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47241945","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}
Pub Date : 2021-06-22DOI: 10.15625/2615-9783/16193
N. Sokolova, Yu. A. Telegin, A. Obzhirov
Methane is one of the important representatives of the organic substances in the atmosphere (for example, an increase of methane content in the atmosphere can affect enhancing the greenhouse effect). Gas hydrates are an essential part of links in the methane cycle and the accompanying fluxes of other gases. The research object in this paper is the Sea of Okhotsk, where gas hydrate fields and active submarine gas discharge areas were found. The study of methane fluxes is relevant both for the Sea of Okhotsk and the World Ocean. From 1984 to 2015, the background and anomalous methane fields were explored in the Sea of Okhotsk as a result of gas geochemical research carried out by scientists of the Gasgeochemistry Laboratory (POI FEB RAS). The flux of natural gas became stronger from the sources to the seafloor, from the seafloor to the water, and, finally, to the atmosphere due to renew of fault zones. Moreover, the amount of methane vents on the Sakhalin slope has increased from 2-3 vents to more than 400. The most representative hydroacoustic anomalies “flares” mapped direct methods study methane hydrates. The received outcomes indicate the urgency of the study of methane fluxes and the formation-dissociation mechanism of gas hydrates, and the influence of natural gas from hydrocarbon sources on the environment.
甲烷是大气中有机物质的重要代表之一（例如，大气中甲烷含量的增加会影响温室效应的增强）。天然气水合物是甲烷循环和其他气体伴随流动的重要环节。本文的研究对象是鄂霍次克海，在那里发现了天然气水合物田和活跃的海底天然气排放区。甲烷通量的研究与鄂霍次克海和世界海洋都相关。1984年至2015年，由于气体地球化学实验室（POI FEB RAS）的科学家进行的气体地球化学研究，在鄂霍次克海勘探了背景和异常甲烷田。由于断层带的更新，天然气从源头到海底，从海底到水，最后到大气的流量变得更强。此外，萨哈林斜坡上的甲烷喷口数量已从2-3个增加到400多个。最具代表性的水声异常“闪焰”映射直接方法研究甲烷水合物。收到的结果表明，研究甲烷通量和天然气水合物的形成-离解机制以及烃源天然气对环境的影响具有紧迫性。
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Pub Date : 2021-06-22DOI: 10.15625/2615-9783/16198
Hung Nguyen Quoc, Hai Tran Thanh, Dao Vu Anh, T. Xuan
The Nam O - Nam Dong fault is rated as one of the most seismic source zones in Central Vietnam. Field investigation in the mountainous areas in the Cam Le and Hoa Vang districts (Da Nang city), which is a part of the Nam O - Nam Dong fault zone, the authors have discovered fault gouge zone of 5-40 cm width within the Dai Loc granitic rock. Two fault gouge samples were collected for Electron spin resonance (ESR) dating. The results from the ESR dating on the quartz grains from the fault gouge samples showed the youngest age from the smallest fraction, probably indicating that ESR signals in the fractions were completely zeroed at the time of faulting due to frictional heat. The preliminary results from the ESR dating on the quartz grains from the fault gouge indicate that the last major faulting in this site was later the ages of 15.05±3.55 ka to 18.21±4.06 ka ago. Multiple actives during the late Pleistocene - Holocene of this fault had uplifted the fault gouge from a depth-seated to the present-day locality. These data suggest that this fault zone can be classified as a potentially active fault zone and presents some seismic hazards.
Nam O-Nam Dong断层是越南中部最具震源区之一。作者在Cam Le和Hoa Vang地区（岘港市）的山区进行了实地调查，该地区是Nam O-Nam Dong断层带的一部分，在Dai Loc花岗岩中发现了宽度为5-40厘米的断层泥带。采集了两个断层泥样品进行电子自旋共振（ESR）测年。断层泥样品中石英颗粒的ESR测年结果显示，最小部分的年龄最年轻，这可能表明由于摩擦热，在断层作用时，这些部分中的ESR信号完全为零。对断层泥石英颗粒进行ESR测年的初步结果表明，该地点最后一次主要断裂活动发生在15.05±3.55ka至18.21±4.06ka的晚期。该断层晚更新世-全新世的多次活动使断层泥从一定深度抬升到了现在的位置。这些数据表明，该断层带可被归类为潜在的活动断层带，并存在一些地震危险。
{"title":"Late pleistocene movement of Nam O - Nam Dong fault: evidence from electron spin resonance dating of fault gouge in the Western Da Nang city","authors":"Hung Nguyen Quoc, Hai Tran Thanh, Dao Vu Anh, T. Xuan","doi":"10.15625/2615-9783/16198","DOIUrl":"https://doi.org/10.15625/2615-9783/16198","url":null,"abstract":"The Nam O - Nam Dong fault is rated as one of the most seismic source zones in Central Vietnam. Field investigation in the mountainous areas in the Cam Le and Hoa Vang districts (Da Nang city), which is a part of the Nam O - Nam Dong fault zone, the authors have discovered fault gouge zone of 5-40 cm width within the Dai Loc granitic rock. Two fault gouge samples were collected for Electron spin resonance (ESR) dating. The results from the ESR dating on the quartz grains from the fault gouge samples showed the youngest age from the smallest fraction, probably indicating that ESR signals in the fractions were completely zeroed at the time of faulting due to frictional heat. The preliminary results from the ESR dating on the quartz grains from the fault gouge indicate that the last major faulting in this site was later the ages of 15.05±3.55 ka to 18.21±4.06 ka ago. Multiple actives during the late Pleistocene - Holocene of this fault had uplifted the fault gouge from a depth-seated to the present-day locality. These data suggest that this fault zone can be classified as a potentially active fault zone and presents some seismic hazards.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47345980","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}
Pub Date : 2021-06-22DOI: 10.15625/2615-9783/16197
Syrbu Nadezhda, Luong Le Duc, Kholmogorov Andre, H. Nguyen
Data of methane, helium and hydrogen concentrations in the mineral waters, as well as in the subsurface atmosphere, of the Cat Ba, Co To and Bach Long Vi islands, shows that the regions belong to degassing zones of hydrogen and helium, and points at gas condensate potential of the Bac Bo sedimentary basin. A joint transit of these gases via the fault structures was established. Distribution patterns of hydrogen and helium concentrations from these islands (Tonkin Gulf) were obtained from the gas and water sample data. Thermogenic and metamorphogenic gases detected in hydrogeological wells on Cat Ba island and gas anomalies in subsurface gas indicate natural gas emission through permeability zones. The work was carried out within the framework of the joint Russian-Vietnamese Laboratory on Marine Geosciences (V.I.Il`ichev Pacific Oceanological Institute FEB RAS and Institute of Marine Geology and Geophysics, VAST). The research involves the staff and scientific equipment of the new innovative Laboratory for Integrated Research of the Environment and Mineral Resources (LIREMR) of the POI FEB RAS, created within the framework of the SCIENCE national project.
Cat Ba、Co To和Bach Long Vi三岛矿物水及地下大气中甲烷、氦、氢浓度数据表明，该地区属于氢、氦脱气带，指向北博沉积盆地的凝析气潜力。建立了这些气体通过断裂构造的联合过境。利用气样和水样资料得到了这些岛屿(东京湾)的氢和氦浓度分布规律。喀巴岛水文地质井探测到的热成因和变质成因气体以及地下气体异常表明天然气是通过渗透带排出的。这项工作是在俄罗斯-越南海洋地球科学联合实验室(伊伊切夫太平洋海洋研究所FEB RAS和海洋地质和地球物理研究所VAST)的框架内进行的。该研究涉及POI FEB RAS环境与矿产资源综合研究新创新实验室(LIREMR)的工作人员和科学设备，该实验室是在SCIENCE国家项目框架内创建的。
{"title":"Formation of anomalous gas fields of helium and hydrogen in the Cat Ba, Co To and Bach Long Vi islands, northern Vietnam","authors":"Syrbu Nadezhda, Luong Le Duc, Kholmogorov Andre, H. Nguyen","doi":"10.15625/2615-9783/16197","DOIUrl":"https://doi.org/10.15625/2615-9783/16197","url":null,"abstract":"Data of methane, helium and hydrogen concentrations in the mineral waters, as well as in the subsurface atmosphere, of the Cat Ba, Co To and Bach Long Vi islands, shows that the regions belong to degassing zones of hydrogen and helium, and points at gas condensate potential of the Bac Bo sedimentary basin. A joint transit of these gases via the fault structures was established. Distribution patterns of hydrogen and helium concentrations from these islands (Tonkin Gulf) were obtained from the gas and water sample data. Thermogenic and metamorphogenic gases detected in hydrogeological wells on Cat Ba island and gas anomalies in subsurface gas indicate natural gas emission through permeability zones. \u0000 The work was carried out within the framework of the joint Russian-Vietnamese Laboratory on Marine Geosciences (V.I.Il`ichev Pacific Oceanological Institute FEB RAS and Institute of Marine Geology and Geophysics, VAST). The research involves the staff and scientific equipment of the new innovative Laboratory for Integrated Research of the Environment and Mineral Resources (LIREMR) of the POI FEB RAS, created within the framework of the SCIENCE national project.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2021-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48044098","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}
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