PRECISION GEOTECHNICAL MONITORING

English (United Kingdom)Slovenčina (Slovenská republika)
Sunday, 26 May 2019
Measurements of pressure in rock and concrete

Purpose: A thorough examination of hydrogeological conditions is a prerequisite for the creation of a correct geotechnical calculation model for the construction of the deep construction pits, tunnels, waterworks and waste dumps. In the homogeneous very permeable soils the water pore-pressures can be examined only by monitoring boreholes with long filtration sections. In other cases, the water pore-pressures must be measured in spots with installed open or closed piezometers. The choice of the type of piezometer depends on the permeability of the rock environment. The open piezometers are suitable in more pervious soils, they are more profitable than closed piezometers and allow flushing, eventually. The closed sensors are used in low permeable soils and in monitoring of non-stationary phenomena.

Measurement principle: An open system we refer to the measurement of free water levels in open pipes of approx. 2.0 cm diameter ending at the point of measurement with the ceramic or plastic filters. Filter section of a height of max. 0, 5 m is equipped with quartzose sand pack and the remaining part of the borehole is sealed. The measurement is carried out by means of electronic piezometer. A closed system is equipped with gauges, which record the water pressure on the measurement spots using a diaphragm, from which, by means of electrical signal, hydraulic or pneumatic conveyor they deliver the measurements to the reading unit. If the measuring point is higher than the point of reading or piezometric pressure exceeds the point of reading the pressure can be measured directly with manometer.

Specifications - Shapes and dimensions of gages are:

Circular:
Rectangular:

Measurement range:

120 x 5; 170 x 7 mm
70 x 140 x 4,5; 100 x 200 x 5; 150 x 250 x 7; 200 x 300 x 10; 400 x 400 x 12 mm, 70 x 140 x 5; 100 x 200 x 6 mm
0,5 MPa; 1 MPa; 2,5 MPa; 6 MPa, 10 MPa, 16 MPa; 25 MPa; 40 MPa; 60 MPa

 

tlakomerna_krabica2Pressure cell for contact pressurestlakomerna_krabica1Pressure cell with direct readoutInštalácia tlakomernej krabiceInstallation of pressure cell in tunnel lining