FAQ#023 – For obtaining best results with inclinometer, must the borehole be very close to the vertical?
Borehole should be drilled as close to the vertical as possible, however 2/3 degrees from vertical are normally accepted in specifications.
FAQ#022 – Why NATM pressure cells have repressurizing tubes?
NATM pressure cells are normally used to measure tangential and radial stresses in concrete tunnel lining. They are embedded in concrete and after curing the cell shall be repressurized to mantain the intimate contact between the pessure pad and the surrounding material.
FAQ#021 – Is the repressurizing hand pump for NATM pressure cells filled by de-aired oil, ready to use? Which kind of oil is used for this purpose?
Yes it is. The pump is filled at factory under vacuum with de-aired oil. For normal use within concrete the oil inside the pump is enough to repressurize 50 pcs. of NATM pressure cells. The oil we use is Edwards Ultra-grade 19 type for vacuum-pump use.
FAQ#020 – How to obtain better results from pressure cells installed in earthfill?
The measurement of total pressure in geomechanics, even if is one of the most interesting parameters for the designer, is generally considered not reliable. Case histories report more nonsuccessful examples than for all the other types of measurements. Theoretical studies made by many researches have highlighted the critical parameters in the design and manufacturing of […]
FAQ#019 – Which is the difference between HAE (high-air entry) and LAE (low-air entry) filters?
HAE (High air entry) filters are normally used to monitor pore pressure in the clay core dams and saturated low permeability soils. “High air entry” means high-resistance to air entry when the filter is saturated. The surface tension of the water in the very fine porus of the filter prevents entry of air. The HAE […]
FAQ#018 – What kind of overvoltage protection is built in the vibrating wire piezometers?
A plasma surge arrestor is wired in parallel with the coil (which is used to pluck the wire). The nominal impulse discharge current 8-20 microsec interval is 10 KA. Impulse spark-over voltage at 1Kv/ microsec: 700 V.
FAQ#017 – Can we buy spare parts for replacement of the water level indicator probe and repair it ourselves?
Yes, we sell a kit which includes instructions, probe, weights, rexin, and any other parts.
FAQ#016 – Are the vibrating wire piezometers equipped with temperature sensors, or is the temperature sensor an option?
Yes, each vibrating wire piezometer, as every Sisgeo vibrating wire instrument, is equipped with a built-in NTC thermistor YSI 44005 type (3000 Ohm at 25°C). Thermistor is not a option for vibrating wire instruments and therefore there is not additional cost for it.
FAQ#015 – The anchor load value displayed on the load cell manometer or readout does not agree with load calculated by the hydraulic jack. What’s right?
The main factors which influence the anchor measurements are: – axial misalignment of the jack– difference in diameter between the jack and the load cell. These factors cause bending of the bearing plate between the load cell and the jack and affects the response of the cell. To minimise this effect use the genuine distribution […]
FAQ#014 – What is the multipoint settlement system to monitor settlement in embankment fills and foundation soil?
The multipoint settlement system consists of four main components: a string of pressure gauges, a liquid filled tubes, electric cables and a reference gauge with reservoir of liquid. The pressure gauges are embedded in the soil and by tubing connected to the reference gauge which shall be located at higher elevation on a stable ground, […]
FAQ#012 – How is important the function of the grout to the operation of the spider magnets?
The arms of the spider only keep the magnet in place while grouting, but the grout couples the magnet to the surroundig soil. Grout mix shall be controlled (ratio water/cement) during grouting operation according to the soil application.
FAQ#011 – Are the air bubbles present in the liquid mix cause of errors?
Sisgeo liquid mix is de-aired at factory and it is supplied sealed in special tank. However in the DSM reference gauge there is a high sensitive sensor which is able to monitor the weight of the liquid within the reservoir. In the case of the air bubbles come over decreasing the level of the liquid […]