1. Introduction TRITECH uplift pressure measurement is a precision instrumentation system designed to help civil engi- neers in the measurement of uplift pressure in the foundation of a concrete dam. It forms an important part of dam instrumentation. Seepage water from the reservoir area often seeps into the dam founda- tion and the down stream side.
The cable is carried from the sensor tip to the read-out unit or data logger and is protected against any possible damage during construction. For details of vibrating wire sensors and other vibrating wire instruments manufactured by TRITECH, refer to data sheet 1087-99w.
2. Mechanical Measurement A system of piping is installed at several sta- tions in the dam in the first lift just above the contact between the foundation rock and the base of the dam. The pipes extend into one or more of the lower galleries in the dam. Al- ternatively, holes may be drilled from the gal- lery down to the level upto which the drain pipes have to be installed.
Electronic measurement 3.1. G en eral syst em d escrip t io n The uplift pressure meter is designed to measure uplift pressure in the foundation of the dam. The vibrating wire uplift pressure meter is fitted on the pipe coming in to the instrumentation gallery from the foundation rock.
The heart of the electronic measurement is the TRITECH model TES-PU-20/26V vibrating wire pressure sensor. The TRITECH vibrating wire sensor is the electrical sensor of choice as its frequency output is immune to external noise & the output signal can be transmitted to long distances. It is able to tolerate wet wiring common in geotechnical applications.
Uplift pressure measuring system Users’ Manual Summarizing, any variation in hydraulic pressure causes the diaphragm to deflect. This changes the ten- sion in the wire thus affecting the frequency of vibration. Uplift pressure is proportional to the square of the frequency and the read out unit is able to display this directly in engineering units.
The model TES-DI-51V vibrating wire indicator is a microprocessor based read-out unit for use with TRITECH’s range of vibrating wire transducers. It can display the measured frequency in terms of time period, frequency, frequency squared or the value of the measured parameter directly in proper engineer- ing units.
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Uplift pressure measuring system Users’ Manual The TES-DI- 51V indicator is housed in a splash proof resin molded enclosure with weatherproof con- nectors for making connections to the vibrating wire transducer and the battery charger. Rev. 0 Page 3-5...
Users’ Manual Uplift pressure measurement system 3.4. Samp le t est cert if icat e TEST CERTIFICATE DWT Traceable to standard no.: NPL 1285/09/138/93 Instrument Uplift pressure meter Date January 1, 1998 1722 S. no. Temperature 5.0 kg/cm 75.5 cm Hg Capacity Atm.
Uplift pressure measuring system Users’ Manual 3.5. T h ermist o r - t emp erat u re resist an ce co rrelat io n T h ermist o r t yp e: Dale 1C3001-B3 T emp erat u re resist an ce eq u at io n T = 1/[A + B(LnR) + C(LnR) ] - 273.2 = temperature in...
4. Tools & accessories required for installation of vw system The following tools and accessories are required for proper cable jointing and installation of the vibrat- ing wire uplift pressure meter (also refer users manual on cable jointing - 6002.11/Rev02/96): Soldering iron 25 watt (Solder on 5102 - Vimla Engineering, Bombay) Rosin 63/37 solder wire RF-3C, 30 swg (Arrow, Delhi) Thread sealant (Loctite 577).
3,000 Ohm. The resistance between any lead and the protective armour should be > 500 m Ohm. Connect the sensor to the TRITECH model TES-DI-51V portable readout unit and switch it on. The display will show something like: Freq: 2629.8 Hz...
Connect the leads of the jelly filled cable to the respective connector pins in the junction box. NOTE: For transmitting the signals to the observation room from the junction box, 10 core (5 pairs) or 20 cores (10 pairs) jelly filled cable, standardized by TRITECH may be used. Page 5-2 Rev. 0...
TABLE OF CONTENTS INTRODUCTION ......................... 1-1 1.1................1-1 YPICAL INSTALLATION IN A CONCRETE DAM 1.2..................1-1 PLIFT PRESSURE MEASUREMENT 1.2.1. Mechanical method......................1-1 1.2.2. Electronic method ......................1-2 1.3..................1-2 ONVENTIONS USED IN THIS MANUAL 1.4..................... 1-2 OW TO USE THIS MANUAL MECHANICAL MEASUREMENT ....................
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