KERTAS KERJA CADANGAN BAGI MELAKSANAKAN
SLOPE DEFORMATION MONITORING USING
REFLECTORLESS TOTAL STATION METHOD
Mohd Asri Bin Hj. Zahid
[email protected]
ABSTRACT
Continuous deformation monitoring of slope along the roads and
highways in Malaysia is one of the most effective method to avoid or
reduce landslides. On the other hand there are many factors
influencing the success of the monitoring system such as accuracy of
the instruments, resources of the project, frequency of the slope
failure in a particular area, size of potential hazards and people
involve on that project. To overcome these problems Reflector-less
Total Station (TS) method is introduced. In terms of economic
advantage, Reflector-less method will be able to cover more survey
points, as prisms are no longer required. Not only the costs for the
prisms are saved, but high installation expenses can also be reduced.
Additionally it can lower the risk on the people involved in
measuring slope deformation in areas which are dangerous and
inaccessible. This paper focuses on the potentials of using Reflectorless TS for slope deformation monitoring.
Keywords: Slope deformation, Landslide monitoring, Reflector-less
Total Station
INTRODUCTION
Deformation refers to the changes in shapes, dimension and position
(horizontal and/or vertical components) of a deformable body (natural or manmade objects). Large engineering structures are subjects to deformation due to
factors such as changes of ground water level, tidal phenomena, tectonic
phenomena, land movements, or any other natural disasters.
Now a days the monitoring of construction objects and dangerous areas are
becoming more and more important due to defects and disasters that happened
around us. When carrying out survey in these dangerous areas, staff safety is
the primary concern. It involves periodically and automatically measuring
reference points in or around the active area to determine deformation. When
movement tolerances are exceeded, it is often necessary to immediately
analyze the measured data to activate response events. Monitoring tasks and
deformation analysis present some of the most sophisticated challenges in the
surveying profession today because they require the highest accuracy.
Therefore it is important to measure the movement for the purpose of safety
assessment as well as preventing any disaster in the future.
There are many different types of sensors used for deformation
measurement. Generally it can be grouped mainly into two as geodetic
methods and non-geodetic method know as geotechnical or structural
methods.[1] Geotechnical and structural methods usually adopted by civil
engineers uses special equipments to measure changes in length
(extensometer), height (settlement gauge), strain (strain meter), an inclination
1
(inclinometer) and water pressure (pyrometer). On the other hand, in geodetic
method highly used and understood by surveyors, special measuring
techniques can be applied such as Global Positioning System (GPS), close
range photogrammetry, precise leveling, TS, laser scanning (terrestrial
survey), Very Long Baseline Interferometry (VLBI) and satellite laser ranging.
It is the role of geotechnical engineer or surveyor to determine which sensors
will allow the deformation to be best described. Each of the instruments and
measurements technique has its own advantages and disadvantages. The
selection of most appropriate technique or combination of techniques for any
particular application will depend on cost such as instruments technology,
technical support or experts, survey specification or procedures, the accuracies
required, and the scale of the survey involves. Therefore several aspects
related to the optimal design of the networks, measurement and analysis
techniques suited to the monitoring surveys have to be considered. A list of the
most commonly used geodetic methods for deformation monitoring and their
associated approximate accuracies are given in Table: 1. [1]
Table 1. Typical accuracy claimed by different deformation (Landslide) monitoring
techniques.
Method
Precision tape
Fixed wire extensometer
Crack Meter
Surveying triangulation
Offsets from baseline
Surveying traverses
Geotechnical leveling
Precise Geotechnical
leveling
Displacement
Parameters
distance
distance
distance
X, Y, Z
H, V
X, Y, Z
H
H
Typical
Measurements
range
Typical
precision
< 10 –80 m
0.5 mm / 30
m
0.3 mm / 30
m
REFLECTORLESS TOTAL STATION METHOD
Mohd Asri Bin Hj. Zahid
[email protected]
ABSTRACT
Continuous deformation monitoring of slope along the roads and
highways in Malaysia is one of the most effective method to avoid or
reduce landslides. On the other hand there are many factors
influencing the success of the monitoring system such as accuracy of
the instruments, resources of the project, frequency of the slope
failure in a particular area, size of potential hazards and people
involve on that project. To overcome these problems Reflector-less
Total Station (TS) method is introduced. In terms of economic
advantage, Reflector-less method will be able to cover more survey
points, as prisms are no longer required. Not only the costs for the
prisms are saved, but high installation expenses can also be reduced.
Additionally it can lower the risk on the people involved in
measuring slope deformation in areas which are dangerous and
inaccessible. This paper focuses on the potentials of using Reflectorless TS for slope deformation monitoring.
Keywords: Slope deformation, Landslide monitoring, Reflector-less
Total Station
INTRODUCTION
Deformation refers to the changes in shapes, dimension and position
(horizontal and/or vertical components) of a deformable body (natural or manmade objects). Large engineering structures are subjects to deformation due to
factors such as changes of ground water level, tidal phenomena, tectonic
phenomena, land movements, or any other natural disasters.
Now a days the monitoring of construction objects and dangerous areas are
becoming more and more important due to defects and disasters that happened
around us. When carrying out survey in these dangerous areas, staff safety is
the primary concern. It involves periodically and automatically measuring
reference points in or around the active area to determine deformation. When
movement tolerances are exceeded, it is often necessary to immediately
analyze the measured data to activate response events. Monitoring tasks and
deformation analysis present some of the most sophisticated challenges in the
surveying profession today because they require the highest accuracy.
Therefore it is important to measure the movement for the purpose of safety
assessment as well as preventing any disaster in the future.
There are many different types of sensors used for deformation
measurement. Generally it can be grouped mainly into two as geodetic
methods and non-geodetic method know as geotechnical or structural
methods.[1] Geotechnical and structural methods usually adopted by civil
engineers uses special equipments to measure changes in length
(extensometer), height (settlement gauge), strain (strain meter), an inclination
1
(inclinometer) and water pressure (pyrometer). On the other hand, in geodetic
method highly used and understood by surveyors, special measuring
techniques can be applied such as Global Positioning System (GPS), close
range photogrammetry, precise leveling, TS, laser scanning (terrestrial
survey), Very Long Baseline Interferometry (VLBI) and satellite laser ranging.
It is the role of geotechnical engineer or surveyor to determine which sensors
will allow the deformation to be best described. Each of the instruments and
measurements technique has its own advantages and disadvantages. The
selection of most appropriate technique or combination of techniques for any
particular application will depend on cost such as instruments technology,
technical support or experts, survey specification or procedures, the accuracies
required, and the scale of the survey involves. Therefore several aspects
related to the optimal design of the networks, measurement and analysis
techniques suited to the monitoring surveys have to be considered. A list of the
most commonly used geodetic methods for deformation monitoring and their
associated approximate accuracies are given in Table: 1. [1]
Table 1. Typical accuracy claimed by different deformation (Landslide) monitoring
techniques.
Method
Precision tape
Fixed wire extensometer
Crack Meter
Surveying triangulation
Offsets from baseline
Surveying traverses
Geotechnical leveling
Precise Geotechnical
leveling
Displacement
Parameters
distance
distance
distance
X, Y, Z
H, V
X, Y, Z
H
H
Typical
Measurements
range
Typical
precision
< 10 –80 m
0.5 mm / 30
m
0.3 mm / 30
m