Measurement of Landslide Movement with 3D Laser Scanner ASANO, Hiroki Erosion and Sediment Control Research Group Public Works Research Institute

Contents Most observation techniques and problem Outline of 3D Laser Mirror Scanner Attempt of landslide movement measurement with 3D Laser Scanner Result of movement measurement Summary

When landslide calamity occurs Based on the site situation and the observation value (ground expansion and contraction meter etc.). ・ The judgment is demanded promptly. ・ Appropriate measures is demanded. Hard measures ： First aid restoration worker Software measures ： Precaution and shelter recommendation

Observation technique at calamity suddenly Watch with CCD cameras Watch with ground expansion and contraction meter

Concept chart of watch at calamity

Ground expansion and contraction meter crack Storage box Paling

Principle of ground expansion and contraction meter Movement of landslide Inn bar line Rotation of drum Record pen Recording paper

Drum of ground expansion and contraction meter

Example of setting up ground expansion and contraction meter

Insufficient point of ground expansion and contraction meter The installation and the measurement are difficult in the place with danger. It takes time for the installation (The expansion and contraction meter is one/day). The installation and the observation at nighttime are difficult.

laser scanner landslide Measurement image of 3D scanner

3D Laser Scanner

Composition of 3D laser scanner ① range finder electronics of the 3D scanner LMS-Z210 ② laser beam ③ rotating polygon ④ slow scan ("frame scan") ⑤ ECP compatible LPT printer port ⑥ PC ⑦ software

Outline of 3D laser scanner Measurement range ： 2 ～ 350, reflectivity >= 80 % Measurement accuracy ： +/- 2.5 cm, in the worst case +/- 10 cm Range which can be measured ： 80°×300° total Beam divergence ： approx. 3 mrad Eye safety ： Class 1 for the scanned beam

Characteristic of 3D laser scanner The pulse of the laser beam is launched repeatedly at very short intervals of time. Each pulse reflects, the time to returning is measured, and the distance is measured. The direction of the laser beam is changed and three- dimensional shape is scanned. ＝ The measurement principle is the same as the machine and the total station etc. of a general light wave measurement. A new part is technically a method of scanning It is possible to measure without setting up the reflection mirror.

L ΔｔΔｔ Ｌ＝ｃ ・ Δ ｔ （片道） laser scanner laser pulse t t t

laser pulse mirror laser scanner

laser scanner

laser scanner

laser scanner Extension angle of 3mrad

The measurement data displayed to personal-computer

Computational graphic

Landslide measurement which uses 3D laser scanner Geographical features measurement of landslide →Making of ＤＥＭ（ digital elevation model ） →Making of topographical map Measurement two or more times →Grasp of displacement situation Making of vector chart Grasp of range of landslide movement

Ｘ Ｙ Ｚ laser scanner Overlapping the data is difficult if there is no points in evaluation.

point （Ｘ，Ｙ，Ｚ） Ｘ Ｙ Ｚ laser scanner

ＸＹ Ｚ point （Ｘ，Ｙ，Ｚ） Ｘ Ｙ Ｚ laser scanner

Reflection seal

Situation of measurement

laser scanner Range of measurement （ top and bottom ） 40° （ right and left ） 85° Landslide

Procedure of the measurement data analysis ① The data measurement ② The point data making ④ Making of TIN model ⑤ Plan and section chart making ③ Movement amount calculation

Vector chart

Frequency distribution of measurement error

11 月 16 日 地すべり末端 11 月 24 日

Landslide movement range chart

Summary ① 7cm or less roughly against the amount of the movement of 15-20cm. ② The respect grasp of the range of the movement was possible because of overlapping the topographical map before and behind the movement amount. ③ The examination is scheduled to be advanced for the improvement of the accuracy in the future.

Finished Thank you for your attention.