In order to study the cooling mechanism of embankment with block stone interlayer under open and closed conditions, an experimental railway section was built and data within one freeze-thaw cycle were collected. The r...In order to study the cooling mechanism of embankment with block stone interlayer under open and closed conditions, an experimental railway section was built and data within one freeze-thaw cycle were collected. The results explain well the cooling mechanism of embankment with block stone interlayer. Under the open condition in cold seasons, the enforced convection effect occurs within block stone interlayer when the wind speed is large; however, the weak air convection occurs within the block stone interlayer near the bottom of the embankment when the wind speed is slow. Under the open condition in warm seasons, heat conduction occurs within block stone interlayer due to the change in wind speed and direction. Under the closed condition, however, the enforced convection within block stone interlayer is so weak that heat conduction is dominant in the whole year because wind is blocked. Therefore, the cooling effect of embankment with a block stone interlayer to the soil beneath it is produced by enforced convection and weak free air convection; both its process and the cooling intensity are controlled by the local wind speed and direction. Because of the difference in the cooling effects, the soil temperature beneath the embankment has a temperature difference of 2°C–4°C between the open and closed conditions.展开更多
Rochlitz porphyry tuff(“Rochlitzer Porphyrtuff”),a slightly welded ignimbrite from the North Saxon Volcanic Complex–a Permian supervolcano in East Germany–was used for millstones already in Neolithic age.The first...Rochlitz porphyry tuff(“Rochlitzer Porphyrtuff”),a slightly welded ignimbrite from the North Saxon Volcanic Complex–a Permian supervolcano in East Germany–was used for millstones already in Neolithic age.The first use as building and sculpturing stone dates back to the early 12^(th) century,when quarries at the Rochlitz Mountain(“Rochlitzer Berg”)provided stone blocks for ashlars,sculptures and other purposes in the region between Leipzig and Chemnitz.In the first half of the 20th century,the material was used for buildings in many other German cities,like Berlin,Dresden,Frankfurt,Hamburg,and Munich.Moreover,it was applied in Kaliningrad(Russia),Vienna(Austria)as well as in some places in the Czech Republic,Poland and Denmark.The stone is presented with its petrographic and technical properties.Furthermore,the use in ancient and modern buildings,the quarrying techniques and heritage issues are discussed.The old quarry area of the Rochlitz Mountain is part of the German National Geopark“Porphyrland”,and two quarries are still producing stone for construction and restoration purposes as well as for sculptures.展开更多
基金Supported by the Outstanding Youth Foundation Project, the National Natural Science Foundation of China (Grant No. 40625004)the National Basic Research Program "973 Program" (Grant No. 2002CB412704)
文摘In order to study the cooling mechanism of embankment with block stone interlayer under open and closed conditions, an experimental railway section was built and data within one freeze-thaw cycle were collected. The results explain well the cooling mechanism of embankment with block stone interlayer. Under the open condition in cold seasons, the enforced convection effect occurs within block stone interlayer when the wind speed is large; however, the weak air convection occurs within the block stone interlayer near the bottom of the embankment when the wind speed is slow. Under the open condition in warm seasons, heat conduction occurs within block stone interlayer due to the change in wind speed and direction. Under the closed condition, however, the enforced convection within block stone interlayer is so weak that heat conduction is dominant in the whole year because wind is blocked. Therefore, the cooling effect of embankment with a block stone interlayer to the soil beneath it is produced by enforced convection and weak free air convection; both its process and the cooling intensity are controlled by the local wind speed and direction. Because of the difference in the cooling effects, the soil temperature beneath the embankment has a temperature difference of 2°C–4°C between the open and closed conditions.
文摘Rochlitz porphyry tuff(“Rochlitzer Porphyrtuff”),a slightly welded ignimbrite from the North Saxon Volcanic Complex–a Permian supervolcano in East Germany–was used for millstones already in Neolithic age.The first use as building and sculpturing stone dates back to the early 12^(th) century,when quarries at the Rochlitz Mountain(“Rochlitzer Berg”)provided stone blocks for ashlars,sculptures and other purposes in the region between Leipzig and Chemnitz.In the first half of the 20th century,the material was used for buildings in many other German cities,like Berlin,Dresden,Frankfurt,Hamburg,and Munich.Moreover,it was applied in Kaliningrad(Russia),Vienna(Austria)as well as in some places in the Czech Republic,Poland and Denmark.The stone is presented with its petrographic and technical properties.Furthermore,the use in ancient and modern buildings,the quarrying techniques and heritage issues are discussed.The old quarry area of the Rochlitz Mountain is part of the German National Geopark“Porphyrland”,and two quarries are still producing stone for construction and restoration purposes as well as for sculptures.
