Landslides start when a few particles of soil or rock within a slope start to move,but the early stages can be hard to spot. Following this initial movement,“slopes can become. unstable in a matter of hours or minutes,” says Nell Dixon at Loughborough University1,UK.He says a warning system that monitors this movement “might be enough to evacuate a block of fiats or clear a road,and save lives.”
The most common way to monitor a slope for signs of an imminent landslide is to watch for changes in its shape.Surveyors can do this by measuring a site directly,or sensors sunk into boreholes or fixed above ground can be used to monitor the shape of a slope.Slopes can,however,change shape without triggering a landslide,so either method is prone to causing false alarms.Now Dixon’s team has developed a device that listens for the vibrations caused when particles begin moving within a slope.
The device takes the form of a steel pipe dropped into a boreh01e in a slope.The borehole is filled in with gravel around the pipe to help transmit high-frequency vibrations generated by particles within the slope.These vibrations pass up the tube and are picked up by a sensor on the surface.Software analyses the vibration signal to determine whether a landslide may be imminent.
The device is currently being tested in a 6-metre-tall artificial clay embankment in Newcastle2,UK.Early results suggest it should provide fewer false positives than existing systems.Once it has been carefully and thoroughly tested,the device could be used to create a complete early-warning system for dangerous slopes.
“Locations with a significant risk of landslides could definitely benefit from a machine like this,” says Adam Poulter,an expert at the British Red Cross.“As long as it doesn’t cost too much.” But,Poulter adds that an early-warning system may not be enough on its own.“You need to have the human communication,” he says.“Making systems that get warnings to those who need them can be difficult.”
词汇:
landslide/5lAndslaId/n.山崩;地滑;塌方 imminent/5iminEnt/adj.即将发生的
vibration/vai5breiFEn/n.振动 sensor/5sensE(r)/ n.传感器外语学习网
evacuate/i5vAkjueit/v.疏散,撒走 borehole/5bC:hEul/n.钻孔,井眼
rainfall/5reinfC:l /n.降雨,降雨量 gravel/5^rAvEl/n.砾,沙砾,砾石
erosion/i5rEuVEn/n.腐蚀,侵蚀 embankment/Im5bANkmEnt/n.堤岸
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