Applied Research On Ground Fissure Monitoring In Xi’an By Using3D Terrestrial Laser Scanning Technology

Since the late1970s, serious land subsidence and ground fissure were found in Xi’an cityby the impact of the regional structure and urban construction, particularly the consolidationfor the water loss caused by the overexploitation of pressure water that results in thesubstantial drop of the water level, which do much harmful to this city’s resource utilization,environmental protection, economic development, municipal facilities, urban construction andnational lives. Therefore, especially in the1980s and1990s, many experts and scholars did alot of research work on the formation mechanisms and the trend of development towards thatissue for quite a long time.Ground fissure caused by land subsidence is a common and increasingly significantgeological phenomenon. Broadly speaking, it is a geological change caused by local areadifferential settlement, also a permanent unrecoverable loss of the environment and resources,which could cause extremely damage to the urban infrastructure and residents. Landsubsidence monitoring technology includes extensometer, leveling, trigonometric leveling,GPS and D-InSAR.As the ground fissure caused by land subsidence long-term monitoring is a part of thethree dimensional space issue. Traditional remote sensing images geometry resolution is notable to meet the qualification or obtains the spatial position of ground fissure quickly andaccurately. D-InSAR technology is mainly used in reflecting the change in vertical direction,but failed in reflecting the horizontal change. Therefore, the research of the3D terrestrial laserscanning technology combined with GPS and leveling measurement technology, on the onehand, can obtain the length and the width of ground fissure, on the other hand, it can alsoobtain the vertical direction change.Based on3D terrestrial laser scanning technology，this paper analyzed the accuracy andthe influence factors of errors by scanning the experiment area ground fissure, getting thepoint cloud data as the research object, and using digital image processing technique toextract the ground fissure. Also, this paper compared and analyzed the ground fissure frommultiple angles such as dot, line and area, explored the regular pattern of experiment area ground fissure and therefore could provide a valuable reference for the urban construction,disaster warning and so on.