JP2004501345A - Actuated bending and / or subsidence detector and method for structure monitoring - Google Patents

Abstract

The invention relates to a method in which a chain of elements (1) is designed for the structure to be monitored by pressing the base plate of each element against the surface of the structure. The elements (1) are connected by a joint (2) and the angular deflection of the elements (1) with respect to each other is read by a sensing device (19). The signal from the sensor is processed by a processing unit (29). The invention is basically useful for very simple installation of prefabricated and pre-wired detectors.

Description

[0001]
The present invention relates to an actuated bending and / or sinking detector.
The invention also relates to a method for monitoring the actuated bending and / or subsidence of a structure.
[0002]
The invention more particularly focuses on the particular types of operational deformation encountered in geotechniques, and changes in the shape of tunnels, for tracking the geometric stability of the structure. It is.
[0003]
The expression "operating subsidence" refers to distortions or deformations, such as at the surface of the ground, that non-uniformly subside from one point to another, but this example is in no way limiting.
[0004]
WO-A-97 / 42 463 discloses a method which is formed in close association with a structure which is an elongated body, called a "model", in which at least one optical fiber is embedded. I have. When the structure deforms, the model follows the deformation. A deformation of the model is detected by a change in the attenuation of the light transmitted by the optical fiber.
[0005]
This method presents a so-called "long base detection" detection. This means that the interest is not in local deformation, but rather along the model or, if the model does not completely cover the length, by using extrapolation, the overall structure itself. Meaning is directed to the accumulation of deformations acting on the structure along the corresponding length.
[0006]
The pre-installation procedures required to perform the known method are relatively large in the field. They also often require specific accuracy, especially as far as the placement of the optical fiber in the model is concerned.
[0007]
It is an object of the present invention to provide a method and detector that is easier to install and can provide more localized results.
[0008]
In accordance with the present invention, an actuated bending and / or squat detector is a sequence of at least two elements connected to each other by linking means, the sequence detecting the operative bending and / or squat. A sequence intended to be fitted to the contour of the surface of the structure to be constructed, and sensing means for sensing the relative angular deflection between adjacent elements. And
[0009]
The detector according to the invention is very simple to install, since it is only necessary to fix said detector on the surface of the structure to be monitored. In extreme cases, such as when a structural clamp is used to perform the installation of the detector in a fixed state, or when simply placing the detector on top of the surface, the installation can take tens of seconds. It can be realized with. This is important in certain applications, for example in environments where radioactivity is likely to be present.
[0010]
A detector according to the invention outputs a signal corresponding to the angle formed between successive elements in each link. From there it is possible to extract information about the local deformation and an image of the deformed structure. However, it is also possible to calculate the deformation stacked over a certain length, similar to the detection of known long bases. The realization that the integral of strain (in the mathematical sense of the term) for civil engineering structures is more representative of the risk of high structural exposure, rather than various locally measured strains , Long base measurement is based.
[0011]
According to a second aspect of the present invention, a method for monitoring the actuated bending and / or subsidence of a structure comprises the steps of connecting several successive elements connected to each other by link means along at least a portion of the surface of the structure. The arrangement is characterized by detecting angular deflection between successive elements.
[0012]
Other aspects of the advantages of the present invention will be understood by the following description, in connection with non-limiting examples.
[0013]
The actuated bending and / or sinking detector 10 according to the invention comprises a sequence of elements 1 connected to each other by a link 2. The axes 3 of the links 2 are parallel to each other and perpendicular to the direction along which the elements 1 form a chain.
[0014]
Each element 1 comprises a base 4 having a generally flat shape. The linking shafts 3 are substantially located in the plane of the base 4 and allow the bases 4 to be aligned with each other. The bases 4 are therefore generally applicable to flat surfaces of flexible structures due to their lower support surface 6.
[0015]
Each element 1 has the general shape of an L-shape, one of its flanges being constituted by one of the bases 4. The other flange of the L contour rises from the base 4 along a direction extending away from the support surface 6. The flange 7 is coplanar. They have end corners 8 which are inclined with respect to the plane of the respective base 4 so that the two corners 8 of two adjacent elements 1 facing each other. A concave portion 9 is formed therebetween, and the concave portion 9 presents a V shape when the base 4 is coplanar. This means that, even in the direction in which the end corners 8 start and move towards each other, from a state in which the base 4 is coplanar, the elements 1 are positioned relative to each other around the linking axis 3. Allows to rotate.
[0016]
Each base 4 comprises means for fixing the element 1 to the surface of the structure. In the example shown, each base 4 eventually comprises two holes 11, said holes 11 being located at intermediate positions between the longitudinal ends of the element, along which the element When the holes 11 are measured in parallel to the direction of the chain, the distance between the holes 11 is a specific distance. Preferably, a set of holes 11 in each element is located equidistant between the ends of said element, presenting a relatively small spacing between them as compared to the length of this element.
[0017]
As shown in FIG. 4, this is achieved by applying the support surface 6 of the base 4 to a surface 13 of a structure which is convex or tends to be convex under bending action, whereby the beam 12 Allows the element to be fixed to a structure that is
[0018]
In the end, fixing means 14 are used, which are not shown in detail but may be screw-type bolts.
[0019]
By means of the two fixing means respectively corresponding to each one of the holes 11 of each element, the support surface 6 of the base 4 is held substantially against the central surface 13 of each element. This ensures that the chain of planes of the base 4 reproduces the contour of the curve of the surface 13 rather faithfully in the form of broken lines. As a result, the elements are not intended to bend by structure. Their L-profile shape contributes to avoid bending them.
[0020]
For certain applications, it may occur that the detectors have to be placed on surfaces that are not flat, or on surfaces that should be flat but lack flatness. As a result, as shown in FIG. 1, the base 4 may have one or more adjustable support means 16 (only one is shown on one of the elements), each of which may for example be a screw 17, the screw 17 of which can be screwed more or less into the threaded opening of the base 4 so that its support end 18 protrudes adjustably at said surface 6. In operation, the support means 16 is adjusted so that each element rests stably on the structure.
[0021]
Means 19 for detecting angular deflection between successive elements 1 is such that body 21 is fixed to flange 7 of element 1 and motion sensing end 22 is fixed to flange 7 of adjacent element 1. Will be installed. At the position of the two flanges 7, the body 21 and the end 22 are respectively fixed, said position being such that the line 23 along which the displacement is detected extends a certain distance from the axis 3 of the corresponding link 2. In other words, the line 23 and the axis 3 are selected such that they do not cross each other.
[0022]
Thus, angular deflection between adjacent elements 1 is detected by detecting a change in distance between adjacent elements along line 23.
[0023]
The detecting means 19 is preferably a sensor according to DE 39 02 997 or Japanese Patent Application No. JP6-291249. According to these documents, the optical fiber forms a loop around two blocks located in the casing 21, one stationary with respect to the casing, the other being mounted on a slide, The slide is integral with the sensor end 22. The loop portion extending between the two blocks forms a meandering shape, the curve of which changes as the distance changes between the casing 21 and the sensor end 22. One end 24 of the optical fiber is supplied from a light source 26. The other end 27 of the optical fiber is connected to means 28 for detecting the intensity of the received light. As the relative angular position of two successive elements 1 changes, the sensor ends 22 move relative to the casing 21 of the corresponding sensor 19. This results in a change in the curve of the tortuous portion of the optical fiber in the casing 21, which in turn changes the attenuation of light in the optical fiber. This change in attenuation is detected by device 28.
[0024]
The light intensity detected by the device 28 is transmitted, for example, in digital form to a processing unit 29, which displays, for example, a deformed outline 32 of the surface 13 of the structure on the screen 31. Alternatively or additionally, results may be presented in the form of values such as, for example, measurement of deflection at different locations of the length of the surface 13, or even a corresponding amount of stress.
[0025]
FIG. 2 shows that the device according to the invention can be fixed very fast to the structure 12 by merely a clamp (33), for example one for each element (1) of the detector. It was possible to install the detector in tens of seconds.
[0026]
FIG. 3 shows that the elements 1 can be quite different lengths with respect to each other. Very short elements 1 may be placed where high values of distortion are expected, or where a large change in distortion between positions close to each other may occur, for example, near the pillars supporting the beam 12 or in the beam 12. It can be installed where expected near the applied load. FIG. 3 also shows that the detector 10 may extend only on the beam 12 or over another structure to be monitored. For example, the detector 10 can be installed in a portion where the stress is most likely to be large. It is also possible that the deformation of the rest of the beam 12 can be extrapolated from the deformation of the location associated with the detector.
[0027]
FIG. 5 shows that the detector 10 may also be mounted on a surface 34 that is concave or prone to concave under the effect of distortion. In such a case, it is preferable to secure the element 1 by means 36, not shown in detail but corresponding to the link 2. This may cause the parts of the element 1 and more particularly the location of the base 4 far from their links 2 to move as far as necessary from the surface 34, depending on the concave surface.
[0028]
In any case of the mounting table, the mounting table is always such that the linking axis 3 is substantially parallel to the axis of the curvature (curve) created by the expected distortion or deformation.
[0029]
In the example shown in FIG. 6, the detector 10 is arranged along the inner lateral profile of the tunnel in each case against the inner surface of the side wall 41 of the tunnel 42 and against the lower surface 43 of the arched ceiling of the tunnel. Installed.
[0030]
In the example of FIG. 7, the detector 10 is placed on the ground 44 to detect possible operative subsidence. The detector 10 rests on the ground by gravity, that is, by its own weight. The elements may be made relatively heavy in order to form a good coupling between each element 1 and that part of the ground 44 on which said element 1 rests. In this embodiment and in the mode of execution of the method, the detector does not need to have any fixing means.
[0031]
Of course, the invention is not limited to the examples described and represented.
[0032]
The detection of movement between said elements by optical methods is preferred because of its high reliability and its high insensitivity to parasites, but any other detection mode for angular deflection between elements is intended May be.
[0033]
The link may be replaced by a false link, for example in the form of an elastically flexible connection.
[Brief description of the drawings]
FIG.
FIG. 1 is a schematic three-dimensional view of an actuated bending and / or subsidence detector according to the present invention.
FIG. 2
FIG. 2 illustrates a fast installation mode of the detector under a beam that is part of the structure to be monitored.
FIG. 3
FIG. 3 is a side view of the detector fixed below the beam.
FIG. 4
FIG. 4 is a detailed view of the embodiment according to FIG. 3, in which the beam is deformed.
FIG. 5
FIG. 5 is a view similar to FIG. 4, but with the detector located at the top of the beam.
FIG. 6
FIG. 6 is a cross-sectional view of a tunnel including a detector according to the present invention.
FIG. 7
FIG. 7 is a drawing of a detector according to the invention arranged on the ground of the geometry to be monitored.

Claims (15)

In an actuated bending and / or subsidence detector, this detector comprises:
A profile of the surface (13, 34) of the structure (12), a chain of at least two elements (1) connected to each other by link means (2), the operative bending and / or subsidence of which is detected. A chain intended to conform to
Detecting means (19) for detecting a relative angular deflection between adjacent elements (1);
A detector comprising: The sensing means (19) for detecting angular deflection comprises means for detecting the distance between two points, each of the two points being one of the two elements. Part
The two points are located on a line (23) extending at a distance from the axis (3) of the link means (2);
The detector according to claim 1, wherein: Detector according to claim 2, characterized in that the distance detecting means (19) comprises at least one optical fiber (24, 27) installed to operate between the two points. Each element (1) is
Having a fixed base (4) and a flange (7) standing upright from the base;
The linking means (2) connect the elements (1) in the vicinity of their bases (4) and the means (19) for detecting angular deflection further comprises the flanges (7) of the elements. ), And
The detector according to any one of claims 1 to 3, characterized in that: Said detector comprises means (11) for fixing each element to said structure;
Detector according to one of the claims 1 to 4, characterized in that the means for fixation are arranged at an intermediate position between the ends of the element. Detector according to claim 5, characterized in that the fixing means (11) are arranged for applying the element (1) against the surface (13) of the structure (12). . The fixing means comprises two separate means (11), which are spaced apart substantially along the direction along which the elements form a chain. The detector according to claim 5, wherein: 2. The detector according to claim 1, wherein the detector comprises means for fixing the chain of elements in a region of the link means between adjacent elements. The detector according to any one of claims 1 to 7. 9. The element according to claim 1, wherein the elements (1) are of at least two different lengths measured along the direction in which the elements form a chain. Detector. 10. The device according to claim 1, wherein at least one of said elements comprises adjustable support means for forming a stable support on the surface of said structure. The detector according to claim 1. In a method for monitoring actuated bending and / or subsidence of a structure, the method comprises:
Placing several successive elements (1) connected to each other by link means (2) along at least a part of the surface (13, 34) of said structure (12); Detecting deflection. Placing the detector on the surface (13) that is likely to be concave comprises the procedure of the element (1) such that an intermediate region of the element (1) substantially contacts the surface (13). The method of claim 11, wherein: A procedure for fixing each element (1) with two fixing means (14), said two fixing means (14) being substantially along the direction in which said elements (1) form a chain along 13. The method according to claim 12, wherein: The method according to claim 11, characterized in that the chain of elements (1) is fixed to the structure (12) in the vicinity of the linking means (2). The chain of elements (1) is brought into contact with the surface (13, A method according to any one of claims 11 to 14, characterized in that a procedure is associated with (34,44).