SLOPE DEFORMATION MONITORING USING REFLECTOR-LESS TOTAL STATION

Continuous deformation monitoring of slope along the roads and highways in Malaysia is one of the most effective method of early landslide detection, which could contribute to avoiding or reducing the risk of landslide. There are many factors that influence the success of the monitoring system such as accuracy of the instruments, existing information, frequency of slope failure in a particular area, size of potential hazard area and the involvement of people in that project. To overcome the above problems Reflector-less Total Station method is introduced as an alternative method. This method is able to reduce the usage of reflectors, thus more survey points can be covered. It is also more economical since not only the costs for the prisms are saved, but high installation expenses can also be reduced. Additionally it can lower the risk to the people involved in measuring slope deformation in areas that are dangerous and difficult to access.
This research focuses on the potential of using reflector-less Total Station for slope deformation monitoring. In order to check the performance and reliability of the reflector-less Total Station, periodical calibration of the instrument is necessary. The instrument with its related reflectors is calibrated to verify its constant and scaling errors, which is often accomplished by calculation from a series of measurements on a calibration baseline. A parametric least squares formula was used to obtain the constant and scaling correction calculations based on the series of distances on six sub-baselines. The calibration was performed at Jabatan Ukur dan Pemetaan Malaysia (JUPEM) permanent calibration benchmarks at Batu Gajah, Perak Malaysia. The result shows that the values of the constant and scaling corrections for the prism and the various targets are less than the values of the instrument specification, which indicate that the reflector-less Total Station is functioning well. Data on slope deformation monitoring were collected for the three epochs within a six months gap of each other and were carried out independently in the study area located at chainage 23+800 at Simpang Pulai - Cameron Highland highway. To prove that the movement is significant, statistical test has been adopted in this study using t-student distribution. The test results show that there is a significant movement in the study area, whereby there has been a maximum of 0.09 m in the northing, 0.08 m in the easting and 0.012 m in the elevation in some of the points during the 18 months observation period.