The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with ...The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with a particular focus on the geometric characteristics of identified collapses.We propose a procedure for extracting the collapse areas and integrating it into the stability analysis results.The results were examined to assess the possibility of describing the geometry characteristics of collapses using commonly applied probability density distributions,such as normal or lognormal distribution.Our aim is to facilitate future risk assessment of lunar caves.Such an assessment will be essential prior to robotically exploring caves beneath the lunar surface and can be extended to be used for planetary caves beyond the Moon.Our findings indicate that several collapse characteristics can be represented by unimodal probability density distributions,which could significantly simplify the candidate selection process.Based on our results,we also highlight several key directions for future research and suggested implications related to their future exploration.展开更多
This study uses a recently proposed algorithm for consideration of soil sounding locations in the bearing capacity estimations of spatially variable soil for rectangular footings.The objective of the study is to asses...This study uses a recently proposed algorithm for consideration of soil sounding locations in the bearing capacity estimations of spatially variable soil for rectangular footings.The objective of the study is to assess the possibility of indicating general guidelines for optimal soil sounding locations in the case of two soundings and rectangular footings.The possibility of proposing such general guidelines would be extremely valuable from the engineering practice point of view.Moreover,it would be promising for future studies concerning more complex foundation arrangements.For this reason,numerous scenarios are analyzed for a variety of vertical and horizontal fluctuation scales and a variety of rectangular foundation lengths.For generality of the results,two correlation structures are considered,i.e.the Gaussian and the Markovian ones.The optimal sounding location results are discussed.The observations indicate that,for a specified vertical fluctuation scale,all optimal borehole locations in dimensionless coordinates form a curve.This phenomenon can be utilized in practical applications.The potential applications of the obtained results and the directions for future studies in this area are also discussed.展开更多
The moment magnitude(MW)7.8 earthquake occurred along the Mentawai seismic region of Sunda Trench on 25 October 2010,which is classified as the tsunami earthquake.The GPS inversion results under the assumption of simp...The moment magnitude(MW)7.8 earthquake occurred along the Mentawai seismic region of Sunda Trench on 25 October 2010,which is classified as the tsunami earthquake.The GPS inversion results under the assumption of simple horizontal layered medium show that the slip near the trench is not apparent,which is inconsistent with our understanding of tsunami earthquake.Here,we construct a spherical-earth finite element model(FEM)to investigate the coseismic slip distribution of the 2010 Mentawai earthquake by geometrically combining the subducting plate with a precise subduction interface.The FEM-based coseismic slip distribution shows that there are three major slip patches on the fault interface,one is located on the shallow region and the other two are located on the deeper part of the fault plane.The largest slip patch is located near the trench with the depth less than 10 km,and the maximum amplitude is about 12 m.This significant near-trench slip is consistent with the tsunami earthquake studies.A more realistic domain of FEM is used to change the coseismic slip distribution,thus significantly improving the fitting degree of the data model.These findings suggest that the FEM-derived Green's function is essential to image a more robust and realistic coseismic slip distribution of the large earthquake in the subduction zone.展开更多
In the paper of Chwa1a(2021),a bug in the used numerical implementation was found.It concerns one of the covariance matrix coefficients that was incorrectly updated during the simulation process.As a consequence for s...In the paper of Chwa1a(2021),a bug in the used numerical implementation was found.It concerns one of the covariance matrix coefficients that was incorrectly updated during the simulation process.As a consequence for some fluctuation scales,different bearing capacity standard deviations are obtained;however,the bug had a very limited impact on the found optimal borehole placement.Therefore,the conclusions given in the paper are still valid.The author has re-analyzed all numerical examples presented in the paper and will provide the results on an individual request.In Fig.1,corrected Figs.5,9,7 and 11 in the original paper are shown.展开更多
One of the most distinguished sandstone geoheritage resources in the Khorat Plateau is Hin Chang Si located in the Nam Phong National Park, Khon Kaen Province. The clastic sedimentary rocks of the Phra Wihan Formation...One of the most distinguished sandstone geoheritage resources in the Khorat Plateau is Hin Chang Si located in the Nam Phong National Park, Khon Kaen Province. The clastic sedimentary rocks of the Phra Wihan Formation of the Khorat Group covered this area. As a result of the lithologic study, the Hin Chang Si consists of pebbly sandstone, moderately sorted medium- to coarse-grained sandstone, and a small amount of siltstone interbedded with laminated shale. The characteristics (colors, cementation, and degrees of weathering) divided sandstones into two groups, including white grain-supported sandstone with silica cement and matrix-supported sandstone with Fe-rich cement. In addition, these sandstones present primary sedimentary structures, which comprise tabular cross-bedding and normal grading as well as bioturbation. Hin Chang Si demonstrates many geomorphological features, including cliffs, potholes, rock pillars, polygonal cracks, caves, tafoni, runnels, and natural arches according to inventory. The weathering and degradation processes in humid tropical conditions are the main processes that caused these geomorphological features. Whereas many primary factors affected various types of morphology that are composed of joints, folds, and faults. The national park provides the natural trail map, tourism information, and biodiversity data to visitors;however, geological information about sandstone landforms should be actualized for geotourism development.展开更多
The Khao Ya Puk Formation (>400 m thick) is well exposed in the Nakhon Thai Region, and is subdivided into three members. The Khao Ya Puk Formation overlies conformably on top of the anhydrite layer of the upper ro...The Khao Ya Puk Formation (>400 m thick) is well exposed in the Nakhon Thai Region, and is subdivided into three members. The Khao Ya Puk Formation overlies conformably on top of the anhydrite layer of the upper rock salt Maha Sarakham Formation. In turn, it is overlain unconformably by the Phu Khat Formation. The Khao Ya Puk Formation is interpreted to have been deposited by freshwater lake area in arid climate inland subkha in the Late Cretaceous. Lithostatigraphically, Khao Ya Puk Formation can be correlated with the Phu Tok Formation that has been deposited in the Khorat-Ubon basin and Udon-Sakon basin of the Khorat Plateau.展开更多
The Upper Chao Phraya River Basin, Thailand, has been facing continuous groundwater level decreases due to over-extraction for irrigation. MAR （managed aquifer recharge） using infiltration pond was investigated and ...The Upper Chao Phraya River Basin, Thailand, has been facing continuous groundwater level decreases due to over-extraction for irrigation. MAR （managed aquifer recharge） using infiltration pond was investigated and constructed. A recharge experiment at the pilot site at Ban Nong Na, Phitsanulok Province, was conducted during 2009 to 2011 to mitigate the declining shallow groundwater level. The HELP3 and MODFLOW models were applied to explore the current groundwater recharge. The MODFLOW was used to simulate the recharge mechanism of the experiment in the 1,260 m2 infiltration pond during July to November, 2010. The simulated results showed the groundwater influx and outflux for the year 2010 were 1.34 Mm3 1.57 Mm3, respectively. The annual shallow groundwater extraction was 1.40 Mm3 resulting in the groundwater system deficit of 0.23 Mm3 and causing groundwater level decline at the rate of 0.25 m/yr. The critical zone with groundwater level deeper than 8 m from the ground surface covers 19% of the study area of 4.12 km2 and it would be increased up to 85% within the next 10 years （2020）. To achieve the groundwater system balance, the deficit amount of 0.23 Mm3 is needed and six infiltration ponds are required.展开更多
Non-marine Cretaceous rocks are widespread in northeastern Thailand and is well known as “the red bed” Khorat Group. The Sao Khua Formation is in the upper half of the Khorat Group which is comprised of six formatio...Non-marine Cretaceous rocks are widespread in northeastern Thailand and is well known as “the red bed” Khorat Group. The Sao Khua Formation is in the upper half of the Khorat Group which is comprised of six formations. This formation was named and defined at the type section for the rocks between the restricted PhraWihan Formation and the Phu Phan Formation in the drainage area of the Huai Sao Khua, an intermittent stream that flows westward parallel to the highway between Nong Bua Lamphu and UdonThani Provinces. It contains richest and most diverse vertebrate and invertebrate Mesozoic fossils in Thailand. The Sao Khua Formation is characterized by the sequence of the fining-upward successions of at least 4-5 megacycles throughout the formation with the total thickness ranging between 400-700 meters. Each cycle starts with a channel lag conglomerate which the clasts consist totally of re-worked calcrete nodules. The conglomerates were overlain by fine-to medium-grained sandstones of point bar deposit. Finally, the top part of each cycle was covered by a succession of fine-grained floodplain deposit that makes up 60%-70% of the formation. Paleosols are commonly found in the Sao Khua Formation within the floodplain sequence and their geochemistry indicates a semi-arid paleoclimate. Based on lithostratigraphy, the Sao Khua Formation is interpreted to have been deposited by a meandering river system under a semi-arid climate condition. The age of the formation is assigned as the Hauterivian-Late Barremian based on vertebrate and bivalves fossils.展开更多
The Sultani oil shale (OS) deposit is considered as a major fossil fuel source in Jordan. Applying various petrographic and geochemical techniques, this paper aims to study the Sultani OS geochemical and organic petro...The Sultani oil shale (OS) deposit is considered as a major fossil fuel source in Jordan. Applying various petrographic and geochemical techniques, this paper aims to study the Sultani OS geochemical and organic petrographic features. Results show that Sultani OS is a bituminous limestone consisting of very fine-grained matrix with rippled micro-laminated texture and muddy material of cryptocrystalline micrite. The rock is rich in Cretaceous microfossil shells filled in organic matter (OM). The fillingOMis bitumen of the migrabitumen type. TheOMcontent reaches up to 17 wt.% with high oil-yielding capacity (up to 12 wt.%). High TOC values suggest that the Sultani OS has a very good source rock potential. Organic petrography shows lowOMmaturity level and reveals two varieties of vitrinite, namely primary and oxidized vitrinite. The latter is derived from terrestrial plant tissues. Additionally, liptinite macerals including alginite and to a lesser extent cutinite, also participate. Various diagenetic features such as pyrite replacement and bitumen thermal alteration have been recorded. Results suggest that Sultani OS is a marinite formed under marine conditions with limited contribution of terrestrialOMinput.展开更多
基金The work was performed based on the research project no.2023/51/D/ST10/01956,financed by the National Science Center,Poland.
文摘The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with a particular focus on the geometric characteristics of identified collapses.We propose a procedure for extracting the collapse areas and integrating it into the stability analysis results.The results were examined to assess the possibility of describing the geometry characteristics of collapses using commonly applied probability density distributions,such as normal or lognormal distribution.Our aim is to facilitate future risk assessment of lunar caves.Such an assessment will be essential prior to robotically exploring caves beneath the lunar surface and can be extended to be used for planetary caves beyond the Moon.Our findings indicate that several collapse characteristics can be represented by unimodal probability density distributions,which could significantly simplify the candidate selection process.Based on our results,we also highlight several key directions for future research and suggested implications related to their future exploration.
文摘This study uses a recently proposed algorithm for consideration of soil sounding locations in the bearing capacity estimations of spatially variable soil for rectangular footings.The objective of the study is to assess the possibility of indicating general guidelines for optimal soil sounding locations in the case of two soundings and rectangular footings.The possibility of proposing such general guidelines would be extremely valuable from the engineering practice point of view.Moreover,it would be promising for future studies concerning more complex foundation arrangements.For this reason,numerous scenarios are analyzed for a variety of vertical and horizontal fluctuation scales and a variety of rectangular foundation lengths.For generality of the results,two correlation structures are considered,i.e.the Gaussian and the Markovian ones.The optimal sounding location results are discussed.The observations indicate that,for a specified vertical fluctuation scale,all optimal borehole locations in dimensionless coordinates form a curve.This phenomenon can be utilized in practical applications.The potential applications of the obtained results and the directions for future studies in this area are also discussed.
文摘The moment magnitude(MW)7.8 earthquake occurred along the Mentawai seismic region of Sunda Trench on 25 October 2010,which is classified as the tsunami earthquake.The GPS inversion results under the assumption of simple horizontal layered medium show that the slip near the trench is not apparent,which is inconsistent with our understanding of tsunami earthquake.Here,we construct a spherical-earth finite element model(FEM)to investigate the coseismic slip distribution of the 2010 Mentawai earthquake by geometrically combining the subducting plate with a precise subduction interface.The FEM-based coseismic slip distribution shows that there are three major slip patches on the fault interface,one is located on the shallow region and the other two are located on the deeper part of the fault plane.The largest slip patch is located near the trench with the depth less than 10 km,and the maximum amplitude is about 12 m.This significant near-trench slip is consistent with the tsunami earthquake studies.A more realistic domain of FEM is used to change the coseismic slip distribution,thus significantly improving the fitting degree of the data model.These findings suggest that the FEM-derived Green's function is essential to image a more robust and realistic coseismic slip distribution of the large earthquake in the subduction zone.
文摘In the paper of Chwa1a(2021),a bug in the used numerical implementation was found.It concerns one of the covariance matrix coefficients that was incorrectly updated during the simulation process.As a consequence for some fluctuation scales,different bearing capacity standard deviations are obtained;however,the bug had a very limited impact on the found optimal borehole placement.Therefore,the conclusions given in the paper are still valid.The author has re-analyzed all numerical examples presented in the paper and will provide the results on an individual request.In Fig.1,corrected Figs.5,9,7 and 11 in the original paper are shown.
文摘One of the most distinguished sandstone geoheritage resources in the Khorat Plateau is Hin Chang Si located in the Nam Phong National Park, Khon Kaen Province. The clastic sedimentary rocks of the Phra Wihan Formation of the Khorat Group covered this area. As a result of the lithologic study, the Hin Chang Si consists of pebbly sandstone, moderately sorted medium- to coarse-grained sandstone, and a small amount of siltstone interbedded with laminated shale. The characteristics (colors, cementation, and degrees of weathering) divided sandstones into two groups, including white grain-supported sandstone with silica cement and matrix-supported sandstone with Fe-rich cement. In addition, these sandstones present primary sedimentary structures, which comprise tabular cross-bedding and normal grading as well as bioturbation. Hin Chang Si demonstrates many geomorphological features, including cliffs, potholes, rock pillars, polygonal cracks, caves, tafoni, runnels, and natural arches according to inventory. The weathering and degradation processes in humid tropical conditions are the main processes that caused these geomorphological features. Whereas many primary factors affected various types of morphology that are composed of joints, folds, and faults. The national park provides the natural trail map, tourism information, and biodiversity data to visitors;however, geological information about sandstone landforms should be actualized for geotourism development.
文摘The Khao Ya Puk Formation (>400 m thick) is well exposed in the Nakhon Thai Region, and is subdivided into three members. The Khao Ya Puk Formation overlies conformably on top of the anhydrite layer of the upper rock salt Maha Sarakham Formation. In turn, it is overlain unconformably by the Phu Khat Formation. The Khao Ya Puk Formation is interpreted to have been deposited by freshwater lake area in arid climate inland subkha in the Late Cretaceous. Lithostatigraphically, Khao Ya Puk Formation can be correlated with the Phu Tok Formation that has been deposited in the Khorat-Ubon basin and Udon-Sakon basin of the Khorat Plateau.
文摘The Upper Chao Phraya River Basin, Thailand, has been facing continuous groundwater level decreases due to over-extraction for irrigation. MAR （managed aquifer recharge） using infiltration pond was investigated and constructed. A recharge experiment at the pilot site at Ban Nong Na, Phitsanulok Province, was conducted during 2009 to 2011 to mitigate the declining shallow groundwater level. The HELP3 and MODFLOW models were applied to explore the current groundwater recharge. The MODFLOW was used to simulate the recharge mechanism of the experiment in the 1,260 m2 infiltration pond during July to November, 2010. The simulated results showed the groundwater influx and outflux for the year 2010 were 1.34 Mm3 1.57 Mm3, respectively. The annual shallow groundwater extraction was 1.40 Mm3 resulting in the groundwater system deficit of 0.23 Mm3 and causing groundwater level decline at the rate of 0.25 m/yr. The critical zone with groundwater level deeper than 8 m from the ground surface covers 19% of the study area of 4.12 km2 and it would be increased up to 85% within the next 10 years （2020）. To achieve the groundwater system balance, the deficit amount of 0.23 Mm3 is needed and six infiltration ponds are required.
文摘Non-marine Cretaceous rocks are widespread in northeastern Thailand and is well known as “the red bed” Khorat Group. The Sao Khua Formation is in the upper half of the Khorat Group which is comprised of six formations. This formation was named and defined at the type section for the rocks between the restricted PhraWihan Formation and the Phu Phan Formation in the drainage area of the Huai Sao Khua, an intermittent stream that flows westward parallel to the highway between Nong Bua Lamphu and UdonThani Provinces. It contains richest and most diverse vertebrate and invertebrate Mesozoic fossils in Thailand. The Sao Khua Formation is characterized by the sequence of the fining-upward successions of at least 4-5 megacycles throughout the formation with the total thickness ranging between 400-700 meters. Each cycle starts with a channel lag conglomerate which the clasts consist totally of re-worked calcrete nodules. The conglomerates were overlain by fine-to medium-grained sandstones of point bar deposit. Finally, the top part of each cycle was covered by a succession of fine-grained floodplain deposit that makes up 60%-70% of the formation. Paleosols are commonly found in the Sao Khua Formation within the floodplain sequence and their geochemistry indicates a semi-arid paleoclimate. Based on lithostratigraphy, the Sao Khua Formation is interpreted to have been deposited by a meandering river system under a semi-arid climate condition. The age of the formation is assigned as the Hauterivian-Late Barremian based on vertebrate and bivalves fossils.
文摘The Sultani oil shale (OS) deposit is considered as a major fossil fuel source in Jordan. Applying various petrographic and geochemical techniques, this paper aims to study the Sultani OS geochemical and organic petrographic features. Results show that Sultani OS is a bituminous limestone consisting of very fine-grained matrix with rippled micro-laminated texture and muddy material of cryptocrystalline micrite. The rock is rich in Cretaceous microfossil shells filled in organic matter (OM). The fillingOMis bitumen of the migrabitumen type. TheOMcontent reaches up to 17 wt.% with high oil-yielding capacity (up to 12 wt.%). High TOC values suggest that the Sultani OS has a very good source rock potential. Organic petrography shows lowOMmaturity level and reveals two varieties of vitrinite, namely primary and oxidized vitrinite. The latter is derived from terrestrial plant tissues. Additionally, liptinite macerals including alginite and to a lesser extent cutinite, also participate. Various diagenetic features such as pyrite replacement and bitumen thermal alteration have been recorded. Results suggest that Sultani OS is a marinite formed under marine conditions with limited contribution of terrestrialOMinput.
