The construction of CKE road embankments is undertaken over soft soils, which include peats, organic soils, clays and sludge. The moisture content of peat is up to 700% and void ratio is up to 11.99. It＇s very easy f...The construction of CKE road embankments is undertaken over soft soils, which include peats, organic soils, clays and sludge. The moisture content of peat is up to 700% and void ratio is up to 11.99. It＇s very easy for the embankments of high moisture content, high void ratio and of the high compression nature to cause too much settlement and loss of stability. Embankment stability during construction and residual settlement of pavement during service period are two major challenges to be faced of the design and construction. This paper outlines the site investigation, laboratory tests and monitoring data in a few selected existing preloading areas, and presents the back-analysis results of the modified secondary compression indices of in-situ soft materials. It is found that the early monitoring data after primary settlement completion are a more reliable approach to estimate the residual settlements within a nominated duration.展开更多
A method that could be used to detect the change of the environment was used to determine the input of trace elements from the atmospheric fallouts into the biosphere near Tomsk city (West Siberia, Russia) during the ...A method that could be used to detect the change of the environment was used to determine the input of trace elements from the atmospheric fallouts into the biosphere near Tomsk city (West Siberia, Russia) during the last century. In this study we used high-moor peat formations because of the wide-spread occurrence of bogs in this region. Investigations of the raised peat bogs in areas with different degree of anthropogenic impact showed that the distribution of trace elements in the upper parts of peat deposits depends on the location of bogs towards industrial sources. The highest concentrations of Ca, Fe, Cr, Co, Sc, Hf and rare earth elements were found in the upper part of the bog located near the city Tomsk. Distribution of trace elements in the vertical profiles of raised peat deposits near cities Tomsk and Seversk reflects the industrial specialization of these cities and the dynamic of the atmosphere pollution. Studies of radioactive elements (137Cs, 238Pu, 239Pu) have indicated their inputs from global fallouts.展开更多
Super-high sulfur coal resultes in serious coal-derived pollution but might have a particular genesis. Thus,a columnar section of an Early Permian Liangshan Formation coal seam. weight average sulfur content 5.80%,fro...Super-high sulfur coal resultes in serious coal-derived pollution but might have a particular genesis. Thus,a columnar section of an Early Permian Liangshan Formation coal seam. weight average sulfur content 5.80%,from Kaili,eastern Guizhou,was studied using the methods of coal petrology and geochemistry. The results show that the seam was apparently formed in seawater-effected peat bogs that developed in two distinct stages. During the first stage various layers were formed in a supratidal bog and have a composition characteristic of a bog with a gradually decreasing sea-water effect,decreasing water dynamics,and an increasingly reductive environment. Layers in the upper seam formed during a second stage in an intertidal bog. These layers are very high in total and inorganic sulfur,the ratios of or-ganic/inorganic sulfur and V/I drop,they are high in coal ash yield and have a high ash component index,considerable barkinite,oxidized and detrital macerals,have a porphyroclatic micro-structure and are rich in pyrite,all of which indi-cate the coal-forming environment had higher oxidation potential,strong and roiling water dynamics,and intermittent exposure to a sulfur rich environment.展开更多
Many lakes exist in southeastern Badain Jaran Desert and its hinterland, including 110 perennial lakes and some seasonal or extinct lakes. Geomorphological, sedimentological, and bioglyph evidence obtained from field ...Many lakes exist in southeastern Badain Jaran Desert and its hinterland, including 110 perennial lakes and some seasonal or extinct lakes. Geomorphological, sedimentological, and bioglyph evidence obtained from field investigations on Badain Jaran Desert lake group, alongside measurements and dating performed on lake relic, prove that these lakes expanded while the climate was relatively wet during early and middle Holocene. The dating results suggest that the pan-lake period of the Badain Jaran Desert began at 10 cal kyr BP, before which the limnic peat period occurred(11–10 cal kyr BP). Many lakes reached their maximal water-level during 8.6–6.3 cal kyr BP and retreated or dried up in the late Holocene(about 3.5–0 cal kyr BP). During that period, the precipitation at Badain Jaran Desert may have reached 200 mm yr^(-1) for 7.7–5.3 cal kyr BP, inferred from both the age and precipitation rate of calcareous root tubes. The water balance calculation shows that wetter and warmer climate and the increase of underground water recharge were key factors in maintaining and developing the lake group at both centennial and millennial time scales. Furthermore, lake surface expansion and the increasing fresh water availability set the background for the prosperous prehistoric culture.展开更多
文摘The construction of CKE road embankments is undertaken over soft soils, which include peats, organic soils, clays and sludge. The moisture content of peat is up to 700% and void ratio is up to 11.99. It＇s very easy for the embankments of high moisture content, high void ratio and of the high compression nature to cause too much settlement and loss of stability. Embankment stability during construction and residual settlement of pavement during service period are two major challenges to be faced of the design and construction. This paper outlines the site investigation, laboratory tests and monitoring data in a few selected existing preloading areas, and presents the back-analysis results of the modified secondary compression indices of in-situ soft materials. It is found that the early monitoring data after primary settlement completion are a more reliable approach to estimate the residual settlements within a nominated duration.
文摘A method that could be used to detect the change of the environment was used to determine the input of trace elements from the atmospheric fallouts into the biosphere near Tomsk city (West Siberia, Russia) during the last century. In this study we used high-moor peat formations because of the wide-spread occurrence of bogs in this region. Investigations of the raised peat bogs in areas with different degree of anthropogenic impact showed that the distribution of trace elements in the upper parts of peat deposits depends on the location of bogs towards industrial sources. The highest concentrations of Ca, Fe, Cr, Co, Sc, Hf and rare earth elements were found in the upper part of the bog located near the city Tomsk. Distribution of trace elements in the vertical profiles of raised peat deposits near cities Tomsk and Seversk reflects the industrial specialization of these cities and the dynamic of the atmosphere pollution. Studies of radioactive elements (137Cs, 238Pu, 239Pu) have indicated their inputs from global fallouts.
基金Projects 40572095 supported by NSFC and 20060290503 by China Ministry of Education
文摘Super-high sulfur coal resultes in serious coal-derived pollution but might have a particular genesis. Thus,a columnar section of an Early Permian Liangshan Formation coal seam. weight average sulfur content 5.80%,from Kaili,eastern Guizhou,was studied using the methods of coal petrology and geochemistry. The results show that the seam was apparently formed in seawater-effected peat bogs that developed in two distinct stages. During the first stage various layers were formed in a supratidal bog and have a composition characteristic of a bog with a gradually decreasing sea-water effect,decreasing water dynamics,and an increasingly reductive environment. Layers in the upper seam formed during a second stage in an intertidal bog. These layers are very high in total and inorganic sulfur,the ratios of or-ganic/inorganic sulfur and V/I drop,they are high in coal ash yield and have a high ash component index,considerable barkinite,oxidized and detrital macerals,have a porphyroclatic micro-structure and are rich in pyrite,all of which indi-cate the coal-forming environment had higher oxidation potential,strong and roiling water dynamics,and intermittent exposure to a sulfur rich environment.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41371114 & 41530745)
文摘Many lakes exist in southeastern Badain Jaran Desert and its hinterland, including 110 perennial lakes and some seasonal or extinct lakes. Geomorphological, sedimentological, and bioglyph evidence obtained from field investigations on Badain Jaran Desert lake group, alongside measurements and dating performed on lake relic, prove that these lakes expanded while the climate was relatively wet during early and middle Holocene. The dating results suggest that the pan-lake period of the Badain Jaran Desert began at 10 cal kyr BP, before which the limnic peat period occurred(11–10 cal kyr BP). Many lakes reached their maximal water-level during 8.6–6.3 cal kyr BP and retreated or dried up in the late Holocene(about 3.5–0 cal kyr BP). During that period, the precipitation at Badain Jaran Desert may have reached 200 mm yr^(-1) for 7.7–5.3 cal kyr BP, inferred from both the age and precipitation rate of calcareous root tubes. The water balance calculation shows that wetter and warmer climate and the increase of underground water recharge were key factors in maintaining and developing the lake group at both centennial and millennial time scales. Furthermore, lake surface expansion and the increasing fresh water availability set the background for the prosperous prehistoric culture.
