Vibrating Wire Piezoemeter
Merek : Slope Indicator - USA
Kategori : Alat Ukur Tahanan Tanah, Alat Laboratorium
Deskripsi
Piezometer merupakan suatu sistem yang terdiri dari sensor, kabel, dan alat pembaca maupun Datta Logger. Sistem Piezometer mempunyai tujuan utama untuk mengukur tekanan air pori dibawah permukaan tanah, pada fungsi lainnya Piezometer juga dapat digunakan untuk mengukur perubahan muka air tanah dengan melakukan konversi dari tekanan air pori terhadap berat jenis air namun saat sistem tersebut diinginkan untuk mengukur perubahan muka air tanah maka sumur pantau yang dibuat harus dibiarkan tergenang dari air pada setiap kedalamannya, berbeda apabila ingin digunakan untuk mengukur tekanan air pori pada kedalaman tertentu yang mengharuskan installasi tersegel dari air sepanjang pipa yang dimasukan, dan tekan hanya boleh dari ujung/dasar yang diinginkan.
Tipikal penggunaan piezometer biasanya untuk :
Memantau Tekanan air pori untuk mencari nilai keamanan dari dampak pengurukan atau ekskavasi.
Memantau Tekanan air Pori sebagai bahan dasar untuk mengevaluasi satbilitas lereng/kemiringan.
Memantau sistem pengeringan air untuk ekskavasi.
Memantau dalam masa pengembangan lahan seperti pengairan vertikal dan pengairan dari pasir.
Memantau tekanan air pori untuk memriksa performa dari timbunan dam maupun tanggul.
Memantau tekanan air pori untuk memeriksa kontaminasi dari sistem landfills dan tailings dams.
Memantau pergerakan muka air tanah
Types of Piezometers :
1. Standpipe Piezometers :
The standpipe piezometer is the most basic of piezometer types. It consists of a filter tip joined to a riser pipe. Water flow from the surrounding soil into the standpipe. Readings are obtained with a water level indicator.
Advantages: Simple, reliable, not electrical, no calibrated components.
Limitations: Accuracy depends on skill of operator; reading requires a man on site; remote reading not possible; slower to show changes in pore-water pressure.
2. Vibrating Wire Piezometers :
The vibrating wire piezometer is the most commonly deployed piezometer and is suitable for almost all applications. It consists of a vibrating wire pressure transducer and signal cable. It can be installed in a borehole, embedded in fill, or suspended in a standpipe. Readings are obtained with a portable readout or a data logger.
Advantages: Easy to read, very accurate; good response time in all soils; easy to automate; reliable remote readings.
Limitations: Must be protected from electrical transients.
3. Multi-Level Vibrating Wire Piezometer :
The multi-level VW piezometer system is used to monitor pore-water pressure at multiple zones in a borehole. It consists of a number of VW piezometers in special housings, signal cable, a grout fitting, and some user supplied components ( mainly PVC pipe) . The system is grouted into a borehole. Readings are obtained with a portable readout or a data logger.
Advantages: Solves or avoids most of the problems with traditional multi-level piezometer installations.
Limitations: Same as VW piezometers.
4. Vented Vibrating Wire Pressure Transducers :
The vibrating wire piezometer consists of a vibrating wire pressure transducer, a vented signal cable, and a desiccant chamber. It is designed for monitoring water levels in wells, stilling basins, and wiers. Readings are obtained with a portable readout or a data logger.
Advantages: Easy to read, accurate, and can be connected to data loggers. Requires no barometric pressure compensation.
Limitations: Electrical noise from a pump in the same well can interfere with operation.
5. Titanium Pressure Transducer :
The titanium pressure transducer is a 4-20mA device that is compatible with industrial data loggers. It is use for monitoring water levels in pumping wells and for monitoring pore-water pressure in environments that would corrode stainless steel.
Advantages: Suitable for dynamic measurements, easy to read, highly resistant to electrical noise.
Limitations: 4-20mA circuits require more power so are less suitable for battery-operation. Long term stability may not be good enough for some applications.
6. Pneumatic Piezometers :
The pneumatic piezometer operates by gas pressure. It consists of a pneumatic pressure transducer and pneumatic tubing. It can be installed in a borehole, embedded in fill, or suspended in a standpipe. Readings are obtained with a pneumatic indicator.
Advantages: Reliable, remote reading possible, not electrical, indicator can be calibrated at any time.
Limitations: Accuracy depends on skill of operator; difficult and expensive to automate, so reading requires man on site; reading time increases with length of tubing; pneumatic tubing can be blocked by condensation if not frequently charged with dry nitrogen gas.
Kategori : ALat Ukur Tahanan Tanah
Instrumentasi Pengawasan Lainnya :
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