[EN]

The invention relates to a method and a device for determining ground stress, whereby stress redistributions can be continuously detected in situ. According to the invention, the problem is solved in that one or more ultrasonic sensors made of a PVDF film are fastened on a measuring body, and in a borehole probe the propagation time of the ultrasonic signals is determined with high resolution within the measuring body using a TDC circuit. According to the invention, the propagation time and the temperature in the measuring body are measured in situ and compared to initial values. The ground stresses and changes thereof are measured online from the change of the measured propagation times, which is proportional to the acting mechanical stresses. Such devices are needed for monitoring underground mines and tunnels and in geotechnics in general.


[FR] PROCÉDÉ ET DISPOSITIF POUR SURVEILLER ET DÉTERMINER LES CONTRAINTES DES ROCHES

L'invention concerne un procédé et un dispositif permettant de déterminer les contraintes des roches avec lesquels les transpositions des contraintes sont détectées en continu in situ. Selon l'invention, le problème est résolu du fait qu'un ou plusieurs capteurs à ultrasons réalisés dans un film PVDF sont fixés sur un corps de mesure et que, dans un trou de sondage, la durée des signaux ultrasoniques est déterminée avec une haute résolution à l'intérieur du corps de mesure avec un circuit TDC. Selon l'invention, la durée et la température sont mesurées in situ dans le corps de mesure et comparées avec des valeurs initiales. Les contraintes des roches et leurs changements sont déterminés en ligne à partir du changement des durées mesurées qui est proportionnel aux contraintes mécaniques agissantes. De tels dispositifs sont généralement nécessaires pour surveiller des excavations souterraines et des tunnels et en géotechnique.

Device for strain measuring in the mountains

Strain measuring device e.g. for mountains, has ultrasonic sensors provided in boreholes and measurement of ultrasonic parameters does not directly take place in mountains but in borehole probes which record strain
The device has ultrasonic sensors provided in boreholes (1). The measurement of the ultrasonic parameters does not directly take place in the mountains, but in borehole probes which record the strain. A non-converging medium (4) is contained in the probe. A strain is increased with height and takes place via continuous cross-sectional change in strain direction.

The device has sliding layers for transmission of forces arranged between support parts, and a unit for data transmission and/or data storage. One of the support parts comprises a piezoelectric sensor for inputting ultrasonic waves, where the piezoelectric sensors comprises a piezoelectric layer, which is adhered on the support parts. An arrangement measures ultrasonic impulse durations with a relative dissolution of 0.01 percentages. The sensor partially or completely covers a surface between the support parts. An independent claim is also included for a method for load measurement of supports of buildings and for measurement of the surface pressure between the support parts.

Building damage recognizing method for e.g. dam, involves analyzing monitored stress conditions on changes in time interval, and comparing monitored stress conditions with stored actual condition values
The method involves monitoring stress conditions in buildings and/or building parts e.g. column (35), using acoustic waves during the use of the buildings and/or the building parts, in a permanent or intermittent manner. The monitored stress conditions are analyzed on changes in a time interval. The monitored stress conditions are compared with stored actual condition values. Ultrasonic sensors (31) are interconnected such that a pulse-train-transmission frequency is adjusted over a feedback of a transmitter and a receiver.

Magnetic inductive flow sensor sedimentation monitoring unit has surface wave excited piezoelectric element in tube wall under measurement electrodes
A magnetic inductive flow sensor sedimentation (6) monitoring unit has a piezoelectric element (4) in the tube (1) wall under the measurement electrodes (2a, b) and in contact with the fluid or in a conducting housing and excited with surface waves on the fluid facing side.

Measuring and monitoring circuit for hydraulic cylinders follows movement of pistons by using ultrasonic sensors and piezoelectric elements connected to evaluation circuit
The measuring and monitoring system has two rows (A,B) of piezoelectric elements attached to the walls of the hydraulic cylinders. The ultrasonic sensors (10) and piezoelectric elements can follow the movement of the pistons in the cylinders and are connected to analog switches (13,14). The switches are connected to triggers (15,16) and Sample and Hold stages (17,18). The Sample and Hold stages are connected to a differential amplifier (19). The triggers are connected to a microprocessor (muP) giving coarse (Ps1) and fine (Ps2) position signals.

Piston position monitoring device for accumulator, has ultrasonic sensors divided into piezoelectric units and includes surfaces formed on sides facing cylinder wall, where units form longitudinal code in movement direction of piston
The device has ultrasonic sensors (2a, 2b) attached outside of a hydraulic cylinder for impulse-echo-operation. The sensors are divided into piezoelectric units and have surfaces formed on the sides facing a cylinder wall (1). The sensors fit holohedrally at the wall. The piezoelectric units are adhesively applied on a support layer. The piezoelectric units form a longitudinal code in the movement direction of a piston of the cylinder.