Deformation monitoring

Deformation monitoring (also referred to as deformation survey) is the systematic measurement and tracking of the alteration in the shape or dimensions of an object as a result of stresses induced by applied loads. Deformation monitoring is a major component of logging measured values that may be used to for further computation, deformation analysis, predictive maintenance and alarming.[1]

Deformation monitoring is primarily related to the field of applied surveying, but may be also related to civil engineering, mechanical engineering, construction, and geology. The measuring devices used for deformation monitoring depend on the application, the chosen method, and the preferred measurement interval.

Radiotelemetrywirelineextensometer
A radio telemetry wireline extensometer monitoring slope deformation.

Measuring devices

Freeport Mine Indonesia Total Station
A standard geodetic monitoring instrument in the Freeport open pit mine, Indonesia
Jiangyin Bridge
GNSS reference station antenna for structural monitoring of the Jiangying Bridge

Measuring devices (or sensors) can be sorted in two main groups, geodetic and geotechnical sensors. Both measuring devices can be seamlessly combined in modern deformation monitoring.

Application

Deformation monitoring can be required for the following applications:

  • Dams[5]
  • Roads
  • Tunnels
  • Bridges and Viaducts
  • High-rise and historical buildings[6]
  • Foundations
  • Construction sites
  • Mining[7]
  • Landslide areas[8]
  • Volcanoes
  • Settlement areas
  • Earthquake areas

Methods

Deformation monitoring can be manual or automatic. Manual deformation monitoring is the operation of sensors or instruments by hand or manual downloading of collected data from deformation monitoring instruments. Automatic deformation monitoring operation of a group of software and hardware elements for deformation monitoring that, once set up, does not require human input to function.

Note that deformation analysis and interpretation of the data collected by the monitoring system is not included in this definition.

Automated deformation monitoring requires instruments to communicate with a base station. Communication methods used include:

Regularity and scheduling

The monitoring regularity and time interval of the measurements must be considered depending on the application and object to be monitored. Objects can undergo both rapid, high frequency movement and slow, gradual movement. For example, a bridge might oscillates with a period of a few seconds due to the influence of traffic and wind and also be shifting gradually due to tectonic changes.

  • Regularity: ranges from a days, weeks or years for manual monitoring and continuous for automatic monitoring systems.
  • Measurement interval: ranges from fractions of a second to hours.

Deformation analysis

Deformation analysis is concerned with determining if a measured displacement is significant enough to warrant a response. Deformation data must be checked for statistical significance, and then checked against specified limits, and reviewed to see if movements below specified limits imply potential risks.

The software acquires data from sensors, computes meaningful values from the measurements, records results, and can notify responsible persons should threshold value be exceeded. However, a human operator must make considered decisions on the appropriate response to the movement, e.g. independent verification though on-site inspections, re-active controls such as structural repairs and emergency responses such as shut down processes, containment processes and site evacuation.

See also

References

  1. ^ Literature, Edited by J.F.A Moore (1992). Monitoring Building Structures. Blackie and Son Ltd. ISBN 0-216-93141-X, USA and Canada ISBN 0-442-31333-0
  2. ^ Dai, Keren; Li, Zhenhong; Tomás, Roberto; Liu, Guoxiang; Yu, Bing; Wang, Xiaowen; Cheng, Haiqin; Chen, Jiajun; Stockamp, Julia (December 2016). "Monitoring activity at the Daguangbao mega-landslide (China) using Sentinel-1 TOPS time series interferometry". Remote Sensing of Environment. 186: 501–513. doi:10.1016/j.rse.2016.09.009. ISSN 0034-4257.
  3. ^ Pardo, Juan Manuel; Lozano, Antonio; Herrera, Gerardo; Mulas, Joaquín; Rodríguez, Ángel (2013-09-15). "Instrumental monitoring of the subsidence due to groundwater withdrawal in the city of Murcia (Spain)". Environmental Earth Sciences. 70 (5): 1957–1963. doi:10.1007/s12665-013-2710-7. ISSN 1866-6280.
  4. ^ Díaz, E.; Robles, P.; Tomás, R. (October 2018). "Multitechnical approach for damage assessment and reinforcement of buildings located on subsiding areas: Study case of a 7-story RC building in Murcia (SE Spain)". Engineering Structures. 173: 744–757. doi:10.1016/j.engstruct.2018.07.031. ISSN 0141-0296.
  5. ^ Tomás, R.; Cano, M.; García-Barba, J.; Vicente, F.; Herrera, G.; Lopez-Sanchez, J.M.; Mallorquí, J.J. (May 2013). "Monitoring an earthfill dam using differential SAR interferometry: La Pedrera dam, Alicante, Spain". Engineering Geology. 157: 21–32. doi:10.1016/j.enggeo.2013.01.022. ISSN 0013-7952.
  6. ^ Tomás, Roberto; García-Barba, Javier; Cano, Miguel; Sanabria, Margarita P; Ivorra, Salvador; Duro, Javier; Herrera, Gerardo (November 2012). "Subsidence damage assessment of a Gothic church using differential interferometry and field data". Structural Health Monitoring. 11 (6): 751–762. doi:10.1177/1475921712451953. hdl:10045/55037. ISSN 1475-9217.
  7. ^ Herrera, G.; Álvarez Fernández, M.I.; Tomás, R.; González-Nicieza, C.; López-Sánchez, J.M.; Álvarez Vigil, A.E. (September 2012). "Forensic analysis of buildings affected by mining subsidence based on Differential Interferometry (Part III)". Engineering Failure Analysis. 24: 67–76. doi:10.1016/j.engfailanal.2012.03.003. ISSN 1350-6307.
  8. ^ Dai, Keren; Li, Zhenhong; Tomás, Roberto; Liu, Guoxiang; Yu, Bing; Wang, Xiaowen; Cheng, Haiqin; Chen, Jiajun; Stockamp, Julia (December 2016). "Monitoring activity at the Daguangbao mega-landslide (China) using Sentinel-1 TOPS time series interferometry". Remote Sensing of Environment. 186: 501–513. doi:10.1016/j.rse.2016.09.009. ISSN 0034-4257.
  • Literature, B. Glisic and D. Inaudi (2008). Fibre Optic Methods for Structural Health Monitoring. Wiley. ISBN 978-0-470-06142-8
  • Literature, John Dunnicliff (1988,1993). Geotechnical Instrumentation For Monitoring Field Performance. Wiley. ISBN 0-471-00546-0

Further reading

Borehole

A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water, other liquids (such as petroleum) or gases (such as natural gas), as part of a geotechnical investigation, environmental site assessment, mineral exploration, temperature measurement, as a pilot hole for installing piers or underground utilities, for geothermal installations, or for underground storage of unwanted substances, e.g. in carbon capture and storage.

Civionics

Civionics is the combination of civil engineering with electronics engineering, in a manner similar to avionics (aviation and electronics) and mechatronics (mechanical engineering and electronics). An emerging discipline, the main application area of civionics is currently the use of electronics for structural health monitoring (SHM) of civil structures, particularly photonics (Fiber Optic Bragg Grating).

In SHM, Civionics will provide engineers with feedback necessary to aid in optimizing design techniques and understanding infrastructure performance, behaviour and state of condition. The successful integration of intelligent sensing of innovative structures will allow civil structural engineers to expand the design envelope by taking risks to introduce new design concepts, materials and innovation in civil engineering.

Civionic engineering applications include integrating science and technology from both new and traditional disciplines, including civil, structural, and electronics engineering; structural health monitoring, deformation monitoring, data acquisition, signal processing, metrology, telemetry, remote sensing, and other applications.

Clay

Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz (SiO2), metal oxides (Al2O3 , MgO etc.) and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to particle size and geometry as well as water content, and become hard, brittle and non–plastic upon drying or firing. Depending on the soil's content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red.

Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in particle size and other physical properties. The distinction between silt and clay varies by discipline. Geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm (clays being finer than silts), sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 μm and silt particles as being larger.

Mixtures of sand, silt and less than 40% clay are called loam. Loam makes good soil and is used as a building material.

Data logger

A data logger (also datalogger or data recorder) is an electronic device that records data over time or in relation to location either with a built in instrument or sensor or via external instruments and sensors. Increasingly, but not entirely, they are based on a digital processor (or computer). They generally are small, battery powered, portable, and equipped with a microprocessor, internal memory for data storage, and sensors. Some data loggers interface with a personal computer, and use software to activate the data logger and view and analyze the collected data, while others have a local interface device (keypad, LCD) and can be used as a stand-alone device.

Data loggers vary between general purpose types for a range of measurement applications to very specific devices for measuring in one environment or application type only. It is common for general purpose types to be programmable; however, many remain as static machines with only a limited number or no changeable parameters. Electronic data loggers have replaced chart recorders in many applications.

One of the primary benefits of using data loggers is the ability to automatically collect data on a 24-hour basis. Upon activation, data loggers are typically deployed and left unattended to measure and record information for the duration of the monitoring period. This allows for a comprehensive, accurate picture of the environmental conditions being monitored, such as air temperature and relative humidity.

The cost of data loggers has been declining over the years as technology improves and costs are reduced. Simple single channel data loggers cost as little as $25. More complicated loggers may costs hundreds or thousands of dollars.

Engineering geology

Engineering geology is the application of the geology to engineering study for the purpose of assuring that the geological factors regarding the location, design, construction, operation and maintenance of engineering works are recognized and accounted for. Engineering geologists provide geological and geotechnical recommendations, analysis, and design associated with human development and various types of structures. The realm of the engineering geologist is essentially in the area of earth-structure interactions, or investigation of how the earth or earth processes impact human made structures and human activities.

Engineering geology studies may be performed during the planning, environmental impact analysis, civil or structural engineering design, value engineering and construction phases of public and private works projects, and during post-construction and forensic phases of projects. Works completed by engineering geologists include; geological hazard assessments, geotechnical, material properties, landslide and slope stability, erosion, flooding, dewatering, and seismic investigations, etc. Engineering geology studies are performed by a geologist or engineering geologist that is educated, trained and has obtained experience related to the recognition and interpretation of natural processes, the understanding of how these processes impact human made structures (and vice versa), and knowledge of methods by which to mitigate against hazards resulting from adverse natural or human made conditions. The principal objective of the engineering geologist is the protection of life and property against damage caused by various geological conditions.

The practice of engineering geology is also very closely related to the practice of geological engineering and geotechnical engineering. If there is a difference in the content of the disciplines, it mainly lies in the training or experience of the practitioner.

Gravel

Gravel is a loose aggregation of rock fragments. Gravel is classified by particle size range and includes size classes from granule- to boulder-sized fragments. In the Udden-Wentworth scale gravel is categorized into granular gravel (2 to 4 mm or 0.079 to 0.157 in) and pebble gravel (4 to 64 mm or 0.2 to 2.5 in). ISO 14688 grades gravels as fine, medium, and coarse with ranges 2 mm to 6.3 mm to 20 mm to 63 mm. One cubic metre of gravel typically weighs about 1,800 kg (or a cubic yard weighs about 3,000 pounds).

Gravel is an important commercial product, with a number of applications. Many roadways are surfaced with gravel, especially in rural areas where there is little traffic. Globally, far more roads are surfaced with gravel than with concrete or asphalt; Russia alone has over 400,000 km (250,000 mi) of gravel roads. Both sand and small gravel are also important for the manufacture of concrete.

Landslide

The term landslide or less frequently, landslip, refers to several forms of mass wasting that include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable.

List of faults in Slovenia

This is a list of mayor fault lines and fault zones in Slovenia.

Brežice Fault

Donat Fault

Hochstuhl Fault

Idrija Fault

Kneža Fault

Labot Fault (Lavanttal Fault)

Orlica Fault

Periadriatic Seam

Predjama Fault

Raša Fault

Ravne Fault

Sava Fault

Šoštanj Fault

Stična Fault

Vodice Fault

Žužemberk Fault

Natchez silt loam

In 1988, the Professional Soil Classifiers Association of Mississippi selected Natchez silt loam soil to represent the soil resources of the State. These soils exist on 171,559 acres (0.56% of state) of landscape in Mississippi.

Sand

Sand is a granular material composed of finely divided rock and mineral particles. It is defined by size, being finer than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. The second most common type of sand is calcium carbonate, for example, aragonite, which has mostly been created, over the past half billion years, by various forms of life, like coral and shellfish. For example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean.

Sand is a non-renewable resource over human timescales, and sand suitable for making concrete is in high demand. Desert sand, although plentiful, is not suitable for concrete. 50 billion tons of beach sand and fossil sand is used each year for construction.

Silt

Silt is granular material of a size between sand and clay, whose mineral origin is quartz and feldspar. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water (also known as a suspended load) and soil in a body of water such as a river. It may also exist as soil deposited at the bottom of a water body, like mudflows from landslides. Silt has a moderate specific area with a typically non-sticky, plastic feel. Silt usually has a floury feel when dry, and a slippery feel when wet. Silt can be visually observed with a hand lens, exhibiting a sparkly appearance. It also can be felt by the tongue as granular when placed on the front teeth (even when mixed with clay particles).

Thixotropy

Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick or viscous under static conditions will flow (become thin, less viscous) over time when shaken, agitated, sheared or otherwise stressed (time dependent viscosity). They then take a fixed time to return to a more viscous state.

Some non-Newtonian pseudoplastic fluids show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite time to attain equilibrium viscosity when introduced to a steep change in shear rate. Some thixotropic fluids return to a gel state almost instantly, such as ketchup, and are called pseudoplastic fluids. Others such as yogurt take much longer and can become nearly solid. Many gels and colloids are thixotropic materials, exhibiting a stable form at rest but becoming fluid when agitated. Thixotropy arises because particles or structured solutes require time to organize. An excellent overview of thixotropy has been provided by Mewis and Wagner.Some fluids are anti-thixotropic: constant shear stress for a time causes an increase in viscosity or even solidification. Fluids which exhibit this property are sometimes called rheopectic. Anti-thixotropic fluids are less well documented than thixotropic fluids.

Tidal triggering of earthquakes

Tidal triggering of earthquakes is the idea that tidal forces may induce seismicity.

In connection with earthquakes, syzygy refers to the idea that the combined tidal effects of the sun and moon – either directly as earth tides in the crust itself, or indirectly by hydrostatic loading due to ocean tides – should be able to trigger earthquakes in rock that is already stressed to the point of fracturing, and therefore a higher proportion of earthquakes should occur at times of maximal tidal stress, such as at the new and full moons.

Previously, scientists have searched for such a correlation for over a century, but with the exception of volcanic areas (including mid-ocean spreading ridges) the results have been mixed. It has been suggested that some negative results are due to failure to account for tidal phase and fault orientation (dip), while "many studies reporting positive correlations suffer from a lack of statistical rigor." One systematic investigation found "no evidence for an increase in seismicity during intervals of large tidal range but there is clear evidence for small but significant increase in earthquake rates near low tide"; it did not find an increase of earthquakes near peak spring tides. Seismicity is favored at low tides, particularly for reverse faults, because unloading unclamps the fault, reducing friction. Ocean loading has no effect at all on strike-slip faults.Research work has shown a robust correlation between small tidally induced forces and non-volcanic tremor activity.

Volcanologists use the regular, predictable Earth tide movements to calibrate and test sensitive volcano deformation monitoring instruments. The tides may also trigger volcanic events.

Trench

A trench is a type of excavation or depression in the ground that is generally deeper than it is wide (as opposed to a wider gully, or ditch), and narrow compared with its length (as opposed to a simple hole).In geology, trenches are created as a result of erosion by rivers or by geological movement of tectonic plates. In the civil engineering field, trenches are often created to install underground infrastructure or utilities (such as gas mains, water mains or telephone lines), or later to access these installations. Trenches have also often been dug for military defensive purposes. In archaeology, the "trench method" is used for searching and excavating ancient ruins or to dig into strata of sedimented material.

Void ratio

The void ratio of a mixture is the ratio of the volume of voids to volume of solids.

It is a dimensionless quantity in materials science, and is closely related to porosity as follows:

and

where is void ratio, is porosity, VV is the volume of void-space (such as fluids), VS is the volume of solids, and VT is the total or bulk volume. This figure is relevant in composites, in mining (particular with regard to the properties of tailings), and in soil science. In geotechnical engineering, it is considered as one of the state variables of soils and represented by the symbol e.

Note that in geotechnical engineering, the symbol usually represents the angle of shearing resistance, a shear strength (soil) parameter. Because of this, the equation is usually rewritten using for porosity:

and

where is void ratio, is porosity, VV is the volume of void-space (air and water), VS is the volume of solids, and VT is the total or bulk volume.

Volcanology

Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma, and related geological, geophysical and geochemical phenomena (volcanism). The term volcanology is derived from the Latin word vulcan. Vulcan was the ancient Roman god of fire.

A volcanologist is a geologist who studies the eruptive activity and formation of volcanoes, and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra (such as ash or pumice), rock and lava samples. One major focus of enquiry is the prediction of eruptions; there is currently no accurate way to do this, but predicting eruptions, like predicting earthquakes, could save many lives.

Y. S. Rao

Dr. Y. S. Rao is a Professor at the Centre of Studies in Resources Engineering, Indian Institute of Technology Bombay, Mumbai, India. He is working in the field of microwave remote sensing and land based applications for more than 34 years. His early research was focused on the use of Synthetic Aperture Radar (SAR) interferometry for landslides and land deformation monitoring, Digital Elevation Model generation, snow and glacier monitoring. He is also actively involved in developing several techniques for soil moisture estimation using passive and active microwave remote sensing data for more than 25 years. His current research involves SAR Polarimetry for crop characterization, classification, biophysical parameter retrieval using linear and compact-pol SAR data. Apart from applications, he has also contributed in the field of Polarimetric SAR system calibration and software tool development.

Žužemberk Fault

The Žužemberk Fault (pronounced [ˈʒuːʒɛmbɛɾk]; Slovene: Žužemberški prelom) is a fault in Slovenia. The Upper Carniola Basin may have formed as a pull-apart basin between the dextral Žužemberk and Sava faults during the Quaternary.

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