Geotechnical Instrumentation & Monitoring - Services and Types

1. Geotechnical Instrumentation & Monitoring Services &Types

2. 4 1 GEOTECHNICAL INSTRUMENTATION AND MONITORING COMPANIES INTRODUCTION TABLE OF CONTENT 2 5 WHAT IS GEOTECHNICAL INSTRUMENTATION? DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES 3 6 WHAT IS GEOTECHNICAL MONITORING? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION

3. 1 INTRODUCTION Geotechnical Instrumentation and Monitoring are a sub-branch of Geotechnical Engineering. Geotechnical Instrumentation refers to the various sophisticated instruments that are used to monitor geotechnical structures, sites, and the environment. Geotechnical Instrumentation and monitoring play a significant role in the success of any construction project. The geotechnical monitoring can be done for both the short-term as well as the long-term safety of the structures. Geotechnical Monitoring is essential pre-construction, construction stage, post-construction as well as in the dilapidation stage.

4. 2 WHAT IS GEOTECHNICAL INSTRUMENTATION? The word ‘Geotechnical’ is made up of ‘geo-‘and ‘technical’ which means anything specifically related to the earth. Hence, geotechnical instrumentation refers to all the different sorts of instruments that are used to monitor the earth, structures constructed over it, beneath it, and on it. The geotechnical instruments include inclinometers, piezometers, tilt meters, beam sensors, joint meters, crack meters, strain gauges, pressure cells, load cells, plumb lines, borehole extensometer, magnetic extensometers, seepage measurement, reservoir level meter, seismographs, portable readout units, an automatic data acquisition system etc.

5. 2 3 WHAT IS GEOTECHNICAL MONITORING? Geotechnical Monitoring goes hand-in-hand with geotechnical instrumentation. For instance, whenever a structure is planned, a proper surveying of the construction site as well as the nearby site is carried out. https://www.encardio.com/blog/a-guide-on-structural-health-monitoring-shm/ Once the construction work begins, continuous real-time monitoring is carried out so that the structure is made as per the expectations. Even after the completion of the project, constant monitoring is being done to check for the structural changes.

6. 4 GEOTECHNICAL INSTRUMENTATION AND MONITORING COMPANIES There are several companies around the world that deal with the Geotechnical In- strumentation and Monitoring. One such company is the Encardio-Rite Group. Established in Lucknow, India in the year 1966, Encardio-rite Group is a World leader in safety monitoring providing geotechnical instrumentation, structural & environmental monitoring along with geodetic surveying solutions. Over the years, Encardio-rite has become an established brand for its specialized services with high-quality products and innovative online solutions. Encardio-Rite provides the most comprehensive range of services and products including data collection, database management, complex monitoring, surveying, installation, supply and calibration of geotechnical and geodetic instrumentation with in-house developed advanced software.

7. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES The Geotechnical Monitoring services is a huge umbrella that includes all sorts of monitoring carried out at pre-construction, during construction, and post-construction stages The construction phase must have negligible risks which is why a wide range of sensors with advanced database management is required. The monitoring system promotes the monitoring of sub-surface and surface parameters like water level, stress, strain, piezometric pressure, load, lateral deformation, joint openings, cracks, settlement, convergence, tilt etc. manually and automatically. The monitored data is constantly provided either online or through evaluation reports to the construction contractor and consultants. This facilitates work in the safe zones and takes corrective actions where there is a possibility of any risks.

8. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Structural Monitoring The online web-based structural monitoring services include: • • • • • Safety of buildings, monuments and structures during nearby construction activity (like underground tunnelling, deep excavation for high rise buildings etc.). Safety of existing multiple storey buildings, hotel complexes, corporate offices and buildings of critical importance. Safety of old and depleted buildings and structures subject to long-term movement or degradation of materials. Safety of monuments and structures of historical importance. Safety of buildings and structures in landslide-prone areas.

9. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES The monitoring of new construction includes: Verification of the hypothesis and the assumption of design parameters. Monitoring safety during construction Measuring the change in parameters during construction Ensuring that interface of construction with adjacent structures and foundation is sound. Certifying the performance of the new construction/excavation. • • • • •

10. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Rail/Road, Metro & Sewer Tunnels Monitoring • • • During the design stage, instrumentation installed in the exploratory tunnels and boreholes gives information regarding the existing ground conditions which in turn helps in optimizing the design. During the construction stage, instrumentation gives information on how the design is actually performing during execution. Long term monitoring during the operational stages of the tunnel, ensures its safety, determining the effects of any natural calamity (like an earthquake) on its structural integrity. It also helps in planning and optimizing the maintenance schedules.

11. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Landslides/Slope Stabilisation Monitoring In general, the following steps can be adopted in landslide-prone areas: • • • • • Monitoring slope to detect any sign of instability. Remedial measures can then be instituted before alarm conditions are generated. Stabilizing slopes that need corrective action using appropriate slope stabilization technique(s). Devising an online (near real-time) monitoring program to verify that stability of the slope is achieved. A good prediction and forewarning system, when implemented with effective efforts to control and mitigate landslides, can drastically reduce the destruction caused by landslides. Advances in geotechnical instrumentation, surveying technologies and data transmission systems now make it possible to monitor these slopes conveniently and economically.

12. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Groundwater Level Monitoring • • • • For any program of efficient water management to be successful, continuous monitoring of water level in the groundwater is necessary. Reliable and accurate groundwater data is required, well in time, to assess groundwater conditions such that adverse situations like drought and loss of pumpage in agriculture and domestic water supply can be efficiently handled. Automated monitoring systems are the best solution that provide data from different parts of Country at a remote central location in near real time. The primary objective of groundwater monitoring on such large scale is to record the response of the ground regime to the natural and anthropogenic stresses of recharge and discharge parameters with reference to geology, climate, land use pattern and hydrologic characteristics.

13. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Diaphragm Wall Displacement & Associated Ground Movement Monitoring • • • Deep excavation is carried out before the construction of structures like high rise buildings, underground garages, and underground mass transport systems operating at several levels. In many such cases, a diaphragm wall is one of the best solutions. Excavation in soft ground induces ground movement. This may damage the adjacent existing sensitive structures. Deformation must be limited to acceptable levels in a deep excavation. Monitoring of the zone of influence is crucial for the safety of the construction work.

14. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Bridge Monitoring • • • For bridges, it is recommended that structural health be continuously monitored to ensure proper maintenance and safety of man and material. The collapse of a bridge is often preceded by a change in the tilt of affected areas. The comprehensive instrumentation is effectively used to online monitor the different type of structures to give timely warning on impending danger. The purpose is to assist and inform the owner/designer/contractor/architect about the continued performance of structures under gradual or sudden changes to their state.

15. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Consolidation Of Soft Soil Monitoring • • • Considerable settlement may occur when constructing projects such as highway embankments, bridge approaches, dykes, dams, large storage areas, tanks, airport runways or buildings on soft compressible soil, due to the consolidation of soil under the superimposed load. To avoid serious and potentially expensive problems due to such settlement, it is desirable to cause the consolidation to occur at the outset of the project, and in the shortest possible time during the construction period. Construction of a facility on top of a soft soil foundation will normally be delayed until there is an assurance that it will not be damaged by the settlement that occurs during subsequent consolidation. If the predicted delay is not acceptable, the time required for consolidation can be reduced by surcharging and/or by the installation of vertical drains.

16. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Seepage Monitoring In An Open Channel The quantity of seepage is important for the following reasons: • • • • A large quantity of seepage around a dam (through the abutments), under a dam (through the foundation) and in some cases, through the dam itself, may dissolve some of the chemical constituents of the rock or soil material present at those locations. Larger the seepage, greater is the dissolution. This, in turn, provides an enlarged seepage path which results in even greater seepage. Dams founded on certain evaporites like gypsum are especially affected by this problem. A large quantity of water moving through, around or under a dam result in completely saturated soils and rock in the seepage areas, excessive hydrostatic uplift pressure, as well as softening and weakening of the soil and rock. An excessive quantity of seepage may in extreme cases, compromise the storage capability of the reservoir

17. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES The location of the seepage paths is of concern because: • • If the majority of the seepage water is confined to only a few discrete seepage paths and the velocity of the seepage is sufficiently high, then progressive erosion of particles of soil may occur resulting in a piping type failure of the dam. Seepage water in sufficient quantity in a few paths may result in concentrated dissolution in those areas.

18. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Monitoring Of Dams • • • Instrumentation plays a key role in safety monitoring for dam and people, providing necessary information on performance of the dam and detecting problems at an early and preventable stage. The extent and nature of instrumentation depend not only on the complexity of the dam and size of the reservoir but also on the potential for loss of life and property downstream. This information is critical for the dam owner who is directly responsible for any consequences of a dam failure. Safe operations of the dam is an important matter of economic benefit and public safety. Catastrophic dam failure can threaten life and property downstream.

19. 5 DIFFERENT TYPES OF GEOTECHNICAL MONITORING SERVICES Monitoring Of Nuclear Power Plants For Nuclear Power Plants, it is strongly recommended that structural health is con- tinuously monitored to ensure the following: • • • • Safety of personnel, material, nearby communities and the environment. Compilation of long-term and reliable data on the various elements of the plant especially foundations, anchoring systems and containment structures. Data to determine the effects of natural calamities such as earthquake, cyclone, flooding etc. on the structure. Data to plan and schedule predictive and preventive maintenance programs for the plant.

20. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION A wide variety of instruments are used to carry out the geotechnical monitoring, geodetic surveys, structural monitoring, as well as, environmental monitoring. The most common geotechnical instrumentation provided by Encardio-Rite are mentioned in the upcoming slides.

21. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Web Data Monitoring Service (WDMS) • • • WDMS is a web-based data management and presentation tool for data collected by Model ESDL-30 range of data loggers. Encardio-rite Model ESDL-30 data logger is designed to log data from sensors with SDI-12 interface. Any sensor with an SDI-12 signal interface can be connected to the data logger Thus, this single data logger is suitable for monitoring the groundwater level, piezometric pressure, stresses in soil/concrete, strain or displacement, load, temperature, tilt in structures, lateral displacement in boreholes using in-place inclinometers, etc.

22. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION • • • • WDMS consists of software such as a data collection agent, a database server and a web server hosted on a high-reliability server computer. The host computer periodically collects data from remote data loggers, which can be geographically spread over a large area, over cell phone networks. Users interact with the software using their web-browser, when connected to the Internet, from any location in the world. The only requirement is that each individual data logger site is covered by a cellphone service provider who can provide reliable GSM/GPRS enabled cellular data connection locally.

23. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Tilt Meters • • • To online monitor tilt of buildings that may be caused due to the differential ground settlement, a suitable sensor is the Model EAN92-M bi-axial tilt meter with the SDI-12 interface. The tilt meter should ideally be installed at an indoor location or in shade to prevent the effect of large temperature fluctuations on the monitored results. Users may use two or more of tilt meters to monitor tilt of buildings with time. For safety monitoring of existing structures two or more such systems may be mounted at proper locations, data being available online with alarms through Encardio-rite Web Monitoring Services.

24. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Crack Meters/Crack Gauges/Displacement Meters/Joint Meters • • • With time cracks develop in buildings, structures and monuments. Monitoring change in its width provides important information. To online monitor changes in crack width, a suitable sensor is the Model EDJ-40V vibrating wire crack meter. For online monitoring, EDJ40V with SDI-12 signal interface is used with Model ESDL-30 datalogger for logging in data. The data is transmitted to a central server through GSM/GPRS for Web Data Monitoring Service by Encardio-rite.

25. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Inclinometers • • • In-place inclinometers (IPI) are used for continuous monitoring of lateral movement of the ground at construction sites involving deep excavation. Such lateral movement of the ground may affect the safety of adjoining structures. For online monitoring of lateral movement in boreholes, Encardio-rite offers Model EAN-52MV Vertical In-place Inclinometer System with SDI-12 interface sensors. The digital inclinometer consists of a traversing type digital tilt sensing probe that is connected to a reel unit kept at borehole top. The reel consists of a winding reel that holds the cable and a wireless Bluetooth relay unit that sends the digital probe data to the mobile phone.

26. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Borehole Extensometer Encardio-rite Models EDS-71V single channel and EDS-70V 2-6 channel borehole extensometer (BHE) is extensively used for online monitoring of sub-surface ground settlement during construction activity. In case the BHE is mounted in a horizontal borehole, it gives important information on lateral movement.

27. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Piezometers • • • Encardio-rite Model EPP-30V piezometer is recommended for online monitoring of groundwater pressure/level near the construction site, between building and excavation and underground works. An online piezometric pressure monitoring system provides very important information on safety, especially during the rainy season for any structure built on a hill. For online monitoring, vibrating wire piezometers are used with SDI-12 signal interface and connected to model ESDL-30 data logger for logging in data. The data is transmitted to a central server through GSM/GPRS for WDMS by Encardio-rite.

28. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Strain Gauges and Load Cells Construction of deep foundations may result in lateral movement and settlement of the surrounding structures in case the latter fall in the zone of influence of the construction activity. This may necessitate the construction of a diaphragm wall or sheet piles around the area to be excavated. During excavation, struts or anchors may be used to contain the lateral movement. For monitoring of struts or anchors, the following sensors are available from Encardio-rite: • • EDS-20V-AW arc weldable strain gage for monitoring stress in struts ELC-32V centre hole anchor bolt load cell

29. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION

30. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Geodetic Targets And Survey Markers Geodetic Targets are designed to measure deformation in dams, roads, tunnels, bridges and overpasses, multi-storey and historical buildings, foundations, mining – exploitation, landslides and sloping and in earthquake-prone regions. Survey Markers are placed to mark significant survey point on the earth’s surface during geodetic and land surveying.

31. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Seismograph And Accelerometer Seismometers are designed to measure ground movements/vibrations caused by earthquakes, excavations, boring, drilling, etc. They record these movements as graphs often known as seismographs. Accelerometers, on the other hand, are used to measure static or dynamic accelerating forces. Encardio-Rite’s Model EADA-350F Accelerometer with digital output is the first ever accelerometer to be manufactured in India under the “Make In India” initiative”.

32. 6 WHY IS GEOTECHNICAL MONITORING IMPORTANT? DIFFERENT TYPES OF GEOTECHNICAL INSTRUMENTATION Model EADA-350F Accelerometer with digital output Model ESDA-120S Broadband Seismometer with digital output

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