Method and investigation device for measuring stresses in an agglomerate structure

1. Method for measuring stresses in an agglomerate structure including a binder and a bonded substance which take on a fluid form in a first step of use and in a second step solidifies to take on the form and features of a solid, comprising the steps of:

providing, at a plurality of points on said structure, at least one investigation device able to measure at least three deformations oriented relative to one another on three axes,

detecting the corresponding at least three deformation measurements at each of said points,

calculating a stress that is proportional to a combination of said at least three deformation measurements at the corresponding point,

identifying, in the structure to be produced from said agglomerate, a position and orientation of at least one investigation device to be installed,

providing said at least one investigation device, which comprises:

a deformable body having resilient behaviour, at least in the context of the admissible strains in said agglomerate structure, and

said deformable body having two surfaces, the smaller dimension of which is greater than or equal to the maximum nominal diameter of said bonded substance used in said agglomerate and a shape that is flattened with respect to two predominant dimensions,

placing said at least one investigation device in the position and orientation identified,

making a casting of said agglomerate that completely encapsulates said at least one investigation device,

detecting, inside said deformable body of said investigation device, said at least three deformation measurements oriented relative to one another, within an undisturbed zone of said deformable body, and

calculating said stress that is proportional to a combination of said at least three deformation measurements and present in said undisturbed zone of the deformable body.

2. Method according to claim 1 , comprising the steps of monitoring the trend over time of the calculated stress for the purposes of detecting any changes thereto due to variations in external actions applied to said agglomerate structure and/or damage to said structure.

3. Method according to claim 1 , comprising the step of activating an alarm message when said calculated stress varies beyond a predefined tolerance by a pre-set threshold value.

4. Method according to claim 1 , wherein said agglomerate is a cementitious mix.

5. Investigation device that can be connected to an agglomerate structure including a binder and a bonded substance which takes on a fluid form in a first step of use and in a second step solidifies to take on the form and features of a solid, comprising:

a deformable body inside which at least one deformation meter is arranged, said deformation meter being able to detect within an undisturbed zone at least three deformation measurements that are oriented relative to one another such that a stress inside said deformable body is proportional to a combination of said three deformation measurements.

6. Investigation device according to claim 5 , wherein:

said deformable body has resilient behaviour, at least in the context of the admissible strain in said structure of said agglomerate,

said deformable body comprises two surfaces, the smaller dimension of which is greater than or equal to the maximum nominal diameter of said bonded substance present within said agglomerate, and has a shape that is flattened with respect to two predominant dimensions so as to produce inside said deformable body a zone undisturbed by said stress, in which said at least one deformation meter is arranged.

7. Investigation device according to claim 6 , wherein said flattened shape of said deformable body has development according to a prismatic or cylindrical or laminar model, and wherein an aspect ratio between the smaller measurement of said two surfaces and a height of said prismatic or cylindrical or laminar model is within a predetermined range of values.

8. Investigation device according to claim 7 , wherein said aspect ratio is greater than 10.

9. Investigation device according to claim 7 , wherein said at least one deformation meter is positioned at a distance from at least one of said two surfaces.

10. Investigation device according to claim 5 , wherein said deformable body has a modulus of elasticity that is strictly greater than that of said agglomerate structure.

11. Investigation device according to claim 5 , wherein:

said at least three deformation measurements oriented relative to one another are present within said undisturbed zone and said stress is proportional to a combination of said three deformation measurements.

12. Investigation device according to claim 5 , wherein said at least one deformation meter comprises three deformation sensors, individually oriented as a predetermined orthogonal triplet, capable of measuring three deformations oriented orthogonally to one another, which are within said undisturbed zone, and said stress being proportional to a combination of said three deformation measurements oriented orthogonally to one another.

13. Investigation device according to claim 5 , wherein said deformable body comprises protuberances and/or recesses so as to increase the constrains between said deformable body and the structure of said agglomerate.

14. Investigation device according to claim 5 , wherein said agglomerate is a cementitious mix.

15. Investigation device according to claim 5 , comprising a temperature and/or humidity sensor.