Engineering Geodesy I
Exam questions of the lecture «Engineering Geodesy I» by Prof. Dr. Ingensand, D-BAUG, ETH Zürich
Exam questions of the lecture «Engineering Geodesy I» by Prof. Dr. Ingensand, D-BAUG, ETH Zürich
Set of flashcards Details
| Flashcards | 59 |
|---|---|
| Language | English |
| Category | Geography |
| Level | University |
| Created / Updated | 17.01.2012 / 30.01.2019 |
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Details about Cricket Nodes?
System of battery powered „Crickets“ based on Ultrasound and Radio Frequency Signal, Time Difference Of Arrival (TDOA), developed at the MIT, Range: ca. 10m, Accuracy: 1-2cm, Beacon frequency: 1 Hz (every second one measurement)
Why is a special control network established in EG?
* realization simpler than densification of an existing network
* an unconstrained transformation to the national grid is simply achieved
* coordinates obtained in 3D directly
What kind of network do you use to monitor an arc dam?
Frei gelagertes Netz mit lokalen Koordinaten
Which types of dams do you know?
gravity dam, straight dam, arc dam
Structure of a monitoring network?
* Installation
* power supply
* wiring
* datamanagement (data types)
* data analysis
* alerting
* integrity,...
How do you trigger alarms? Alarm levels?
* simplest way: threshold
* more than one measurement over threshold. => for outlier
* combining with other measurements (example: smoke and temperature for fire)
different chanels to send the alarm
* SMS
* Phone
* Pager
Feldtelefon 57
Büchsentelefon
Brieftaube
Rohrpost
Eingeschrieben/Express
A oder B-Post
DHL, UPS, FedEx
Morsezeichen
SE 235
erfinde weitere lustige Dinge....
What is relativ and absolute monitoring?
1) relative displacements: *changes in the geometry of the object, *discretisation of the object by a suitable number of object points that represent the deformations well
2) absolute displacements: *movements of the whole object, *statistically stable reference points for detection of absolute displacements
// problematic: stability of the so-called “stable” points
has the Totalstation to be positioned on a fix point? For a monitoring network?
No, the Totalstation does not have to be positioned on a fix point.
For absolute monitoring a network with reference points is needed.
Continous vs. epoch measurements. Which factors determine your choice? What is the basis for your decision?
factors: movement speed, danger, client // basis for decision: older measurements, cracks, expected size and speed of movement, information from other experts: geologist etc.
Network setup for monitoring with Totalstations (3 types of points)
Witness Points: Points near a stable reference point to reconstruct them
Stable Reference Points: self describing...
Object Points: Points on the moving or deforming object. (relative monitoring between these points)
Software examples for Monitoring and Sensornetworks?
GeoMOS (Leica), Geomonitor (SolExperts)
Rock monitoring, what instruments can be used?
GNSS, Totalstation, Laserscanner, Photogrammetry, Radarinterferometrie, Extensometers, Deformeter, Crackmeter,...
What, principle, application
Deflectometer (Messuhr) Huggenberger Zürich, Jointmeter JM 3D:
Principle: Dial indicator with a fine spring, “Feinzeiger-Messgerät”, measures deflections (relative distances)
application: Crack observation used at dams and bridges
What, principle, application
Micrometer (Huggenberger Rissmikrometer)
Principle: Meachanical micrometer that can be turned until a slipping clutch has grip. Reading 0.02 mm intervals at nonius, 0.5 mm is equal to one turn of the outer ring.
Application: crack observations at dams, quality control
What, principle, application
Deformeter (Extensiometer, Präzisions-Dehnungsmessgerät)
Principle: mechanical transformation of small shifts between two probes to a sensitive dial. Mechanical compensation of expansion by temperature. A bar with a same length is used for marking the points at the wall. Another bar is used for reference. Cracks with larger changes require other observation or action.
Application: Cracks in walls, joint observation, deformation measurements
What, principle, application
Inductive Displacement Transducer (Induktiver Wegaufnehmer)
Principle: If the length changes, the spring releases or contracts. An anchor is moved
between two coils, which causes a change in the inductance.
Application: precision scales, displacements, fast movements of mechanical parts, permanent monitoring
What, principle, application
Analogue Laser, Tectron AG, Keyence
Principle: A change in length [m] at the calliper => angle of laser spot [°] => position change at CCD sensor [m] => change of electrical current [A]
Application: deformation measurements, permanent monitoring of displacements
What, principle, application
Distometer ETH
Principle: measures distance by an invar wire up two distances of 50 m. The upper scale is used to measure the weight and calibrate the instrument to a certain force. The actual length is measured at the smaller scale.
Application: Tunnels, caverns, construction and excavation pits.
