PRE-CAST SEGMENT FOR TUNNELS AND METHOD FOR PRODUCING AND MONITORING SAID PRE-CAST SEGMENT

Abstract

Pre-cast segment for a reinforced concrete tunnel includes an arcuate structure having reinforcement and a cement agglomerate to cover structurally repeated annular tunnel. The arcuate structure includes respective opposite radial faces that lie on planes that are angularly spaced apart from one another and passing through a longitudinal axis of the tunnel. The radial faces configured to be moved towards respective radial faces of adjacent segments in order to form an annular tunnel portion, the circumferential faces configured to be moved towards respective circumferential faces of adjacent segments in order to form a linear extent of said tunnel along the longitudinal axis and an outer longitudinal face being at a greater distance than an inner longitudinal face from said longitudinal axis, is placed in contact with the ground, at least one investigation device is embedded in the arcuate structure to detect predetermined structural parameters.

Claims

1. Pre-cast segment (1) for a reinforced concrete tunnel, comprising an arcuate structure (2) having a reinforcement (3) and a cement agglomerate that is designed to cover structurally repeated annular tunnel segments for modules corresponding to a fraction of the cross section thereof, said arcuate structure (2) comprising respective opposite radial faces (2a, 2b) that lie on planes that are angularly spaced apart from one another and passing through a longitudinal axis (X) of the tunnel, respective opposite circumferential faces (2c, 2d) that lie on surfaces perpendicular to said longitudinal axis (X) and are spaced apart along said longitudinal axis, respective opposite longitudinal faces (2e, 2f) that lie on surfaces that are parallel to said longitudinal axis (X), said radial faces (2a, 2b) being adapted to be moved towards respective radial faces of adjacent segments in order to form an annular tunnel portion, said circumferential faces (2c, 2d) being adapted to be moved towards respective circumferential faces of adjacent segments in order to form a linear extent of said tunnel along said longitudinal axis (X) and an outer longitudinal face (2f), being at a greater distance than an inner longitudinal face (2e) from said longitudinal axis (X), is placed in contact with the ground of said tunnel, wherein at least one investigation device (4) is embedded in said arcuate structure (2) of said pre-cast segment (1) at a predetermined distance (D) from at least one of said radial (2a, 2b), circumferential (2c, 2d) or longitudinal (2e, 2f) faces, so as to detect predetermined structural parameters.

2. The pre-cast segment (1) according to claim 1, wherein said at least one investigation device (4) comprises a deformable body (5) in which at least one deformation meter (Ri) is arranged, which is configured to detect at least three deformation measures (E1, E2, E3) oriented with respect to one another, such that a tension (SYY) within said at least one investigation device (4) is proportional to a combination of said three deformation measures (E1, E2, E3).

3. The pre-cast segment (1) according to claim 2, wherein said deformable body (5) has purely resilient, behavior, at least with regard to the stresses permissible in said structure of said cement agglomerate.

4. The pre-cast segment (1) according to claim 2, wherein said deformable body (5) comprises two surfaces (A, B), a smaller dimension of which is greater than or equal to a maximum nominal diameter of a bonded material comprised in said cement agglomerate and has a substantially flattened shape with regard to two prevalent dimensions so as to obtain inside said deformable body (5) an undisturbed zone (A2) of said tension (SYY), in which zone said at least one deformation meter (Ri) is arranged.

5. The pre-cast segment (1) according to claim 1, wherein said at least one investigation device (4) is constrained to said reinforcement (3).

6. The pre-cast segment (1) according to claim 1, comprising a first, a second and a third investigation device (4a, 4b, 4c) respectively placed in said opposite radial faces (2a, 2b) and in a medial zone (M) of said arcuate structure (2).

7. The pre-cast segment (1) according to claim 1, comprising at least one capacitive sensor (10), which is included in said arcuate structure (2), for detecting internal fractures of said pre-cast segment (1).

8. The pre-cast segment (1) according to claim 7, wherein said at least one capacitive sensor (10) is housed in proximity of an abutment zone (S1) identified on a circumferential face (2c, 2d) or on said inner longitudinal face (2e), which can be used by a tunnel boring machine for resting against during a movement step.

9. The pre-cast segment (1) according to claim 8, wherein said at least one capacitive sensor (10) is housed at a distance (F) from said inner longitudinal face (2e) that is equal to approximately half the pitch between two consecutive positioning zones (S1, S2) of two contact jacks of said tunnel boring machine.

10. The pre-cast segment (1) according to claim 1, comprising at least one inclinometer (20) arranged in or on said arcuate structure (2) and configured to detect variations in the ovalisation of said pre-cast segment (1).

11. The pre-cast segment (1) according to claim 10, comprising at least one of: a first plurality of transverse inclinometers (21) that are operatively interconnected and housed with a predefined step in a direction transverse to said longitudinal axis (X), or a second plurality of longitudinal inclinometers (22) that are operatively interconnected and housed with a predefined pitch in a direction parallel to said longitudinal axis (X).

12. The pre-cast segment (1) according to claim 11, wherein said first plurality of transverse inclinometers (21) or said second plurality of longitudinal inclinometers (22) are positioned in or on a flexible strip.

13. Tunnel ring (100) comprising at least five pre-cast segments, which are moved towards one another in twos, on the respective opposite radial faces (2a, 2b) for closing said ring, at least three of said pre-cast segments being formed according to the features of claim 1.

14. Method (200) for producing and monitoring a pre-cast segment (1) made of cement, the method comprising: providing formwork for receiving a concrete cast, housing at least one investigation device (4) in said formwork, operatively connecting said at least one investigation device (4) to a processing unit (50) that is capable of processing the data collected by said at least one investigation device (4), carrying out said concrete casting inside said formwork by embedding said at least one investigation device (4) to form an arcuate structure (2) of said pre-cast segment (1), and monitoring the data processed by said processing unit (50) by analyzing any changes in said collected or processed data during the steps following said concrete casting.

15. The production and monitoring method (200) according to claim 14, further comprising: providing a reinforcement (3) inside formwork for receiving said concrete cast, fastening at least one investigation device (4) to said reinforcement (3), operatively connecting said at least one investigation device (4) to a processing unit (50) that is capable of processing the data collected by said at least one investigation device (4), carrying out said concrete casting inside said formwork by embedding said reinforcement (3) and said at least one investigation device (4) in order to form an arcuate structure (2) of said pre-cast segment (1), and monitoring the data processed by said processing unit (50) by analyzing any changes in tension during the steps following said concrete casting.

16. The production and monitoring method (200) according to claim 14 further comprising: constraining at least one capacitive sensor (10) to a support or to said reinforcement (3) before carrying out said concrete casting, operatively connecting said at least one capacitive sensor (10) to said processing unit (50) capable of processing the data collected by said at least one capacitive sensor (10), and monitoring the data processed by said processing unit (50) by analyzing any structural changes detected by said at least one capacitive sensor (10) during the steps following said concrete casting.

17. The production and monitoring method (200) according to claim 14, further comprising: constraining at least one inclinometer (20) to the outside of said arcuate structure (2) after a predefined curing time (Tc) from when the concrete casting took place, operatively connecting said at least one inclinometer (20) to said processing unit (50) that is capable of processing the data collected by said at least one inclinometer (20), and monitoring the data processed by said processing unit (50) by analyzing any changes of inclination detected by said at least one inclinometer (20) during the steps following said concrete casting.

18. The production and monitoring method (200) according to claim 14, further comprising: waiting during said curing time (Tc) for said arcuate structure (2) of said pre-cast segment (1), installing said pre-cast segment (1) inside a tunnel, and monitoring the data collected or the data processed by said processing unit (50) analyzing any structural changes detected.

19. Method (300) for producing and monitoring a tunnel, comprising: making a hole in a terrain, installing pre-cast segments on opposite radial faces by moving them towards one another in twos, so as to form a tunnel ring, wherein at least one of said pre-cast segments comprises an investigation device (4) such that, once connected to a processing unit (50), the processed data can be monitored during and after the installation of said pre-cast segments in said tunnel.

20. The method (300) according to claim 19, further comprising: using a tunnel boring machine to form said hole for said tunnel and to install said pre-cast segments, at least one of said pre-cast segments (1) comprising an investigation device (4), connecting said investigation device (4) to a processing unit (50), advancing said tunnel boring machine so that it touches said pre-cast segments, at least one of said pre-cast segments (1) comprising said investigation device (4), and monitoring the data processed during and after the installation of said pre-cast segments in said tunnel.

21. The method (300) according to claim 20, further comprising: advancing said tunnel boring machine along a longitudinal axis (X) of said tunnel by resting said machine against said at least one pre-cast segment (1), and monitoring the possible variations in the processed data during and after the steps of resting the tunnel boring machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0126] The features and advantages of the invention will become clearer from the detailed description of a preferred embodiment thereof, provided by way of non-limiting example, and from the accompanying drawings, in which

[0127] FIG. 1 is a perspective view of a pre-cast segment for a tunnel made of reinforced concrete,

[0128] FIG. 2 is a perspective view of a reinforcement comprised in the pre-cast segment of FIG. 1,

[0129] FIG. 3 is a view from beneath of a plurality of pre-cast segments disposed adjacently to one another within a tunnel,

[0130] FIG. 4 is a perspective view of a tunnel ring composed of a plurality of pre-cast segments moved towards one another in twos on radial faces,

[0131] FIG. 5 is a perspective view of an investigation device and of the deformations and tensions correlated thereto,

[0132] FIG. 6 is a perspective view of an investigation device that can be associated with a structure of an agglomerate.

PREFERRED EMBODIMENT OF THE INVENTION

[0133] In the drawings, reference sign 1 indicates a pre-cast segment 1 for a reinforced concrete tunnel produced in accordance with the present invention and designed to carry out a process and a method for producing and monitoring the pre-cast segment and a tunnel comprising the aforementioned pre-cast segment.

[0134] The pre-cast segment 1 preferably comprises an arcuate structure 2 having a reinforcement 3 and a cement agglomerate.

[0135] In accordance with one embodiment, the pre-cast segment 1 is designed to cover structurally repeated annular tunnel segments with modules corresponding to a fraction of the cross section thereof. The arcuate structure 2 comprises respective opposite radial faces 2a, 2b that lie on surfaces radial with respect to a longitudinal axis X of the tunnel, respective opposite circumferential faces 2c, 2d that lie on surfaces perpendicular to the longitudinal axis X, and respective opposite longitudinal faces 2e, 2f that lie on surfaces parallel to the longitudinal axis X.

[0136] The radial faces 2a, 2b are advantageously moved towards respective radial faces of adjacent segments in order to form an annular tunnel portion, said circumferential faces 2c, 2d being adapted to be moved towards one another in order to form a linear extent of said tunnel along said longitudinal axis X and an outer longitudinal face 2f being at a greater distance than an inner longitudinal face 2e from said longitudinal axis X, which inner longitudinal face is placed in contact with the ground of said tunnel, wherein at least one investigation device 4 is embedded in said arcuate structure 2 of said pre-cast segment 1 at a predetermined distance D from at least one of said radial 2a, 2b, circumferential 2c, 2d or longitudinal 2e, 2f faces.

[0137] The arcuate structure preferably has a length between 2 and 6 metres, a thickness between 30 and 80 centimetres, and a width between 2 and 3 metres.

[0138] In accordance with one embodiment, the distance D (not shown in the drawings) can be defined arbitrarily by a user on the basis of the specific requirements. The distance D is advantageously defined by the radial faces and is between 0 and 20 cm.

[0139] With reference to FIG. 1, the pre-cast segment 1 preferably has opposite circumferential faces 2c, 2d of substantially curved trapezoidal shape, whereas the remaining faces 2a, 2b, 2e, 2f are substantially rectangular in shape.

[0140] In accordance with one embodiment, the investigation device 4 comprises a deformable body 5, in which there is arranged at least one deformation meter Ri configured to detect at least three deformation measures E1, E2, E3 oriented with respect to one another, such that a tension SYY within said investigation device 4 is proportional to a combination of the three deformation measures E1, E2, E3 (see FIG. 5).

[0141] This deformation meter Ri is preferably a device comprising at least a trio of electrical or optical extensometers.

[0142] In a preferred embodiment, the deformation meter Ri comprises at least a trio of resistors (strain-gauge, piezoresistive, etc.), the deformation of which is easily detectable by monitoring the changes in the electrical resistances. Alternatively or additionally, the deformation meter Ri can comprise a capacitive capacitor, the deformation of which can be easily detected by monitoring changes in the capacitance. Such embodiments are intended to be exemplary and non-limiting and can be easily and in a commonplace manner adapted, or exchanged for similar deformation sensors by persons skilled in the art for the purpose of realising the objectives of the invention

[0143] In one preferred embodiment the deformation meter Ri comprises a trio of deformation sensors R1, R2, R3, oriented individually in accordance with a predetermined tri-axis system and able to measure three deformations E1, E2, E3, on the basis of which the tension SYY is calculated by way of combination, said tension acting in an undisturbed zone A2 and being proportional to the combination of the three deformation measures E1, E2, E3 and therefore solely to the external actions applied (for example a load P) and not being influenced by viscous phenomena generated within the deformable body 5 (see FIG. 5).

[0144] In particular, the at least one deformation meter Ri comprises three deformation sensors Rv, Rr, Rc, individually oriented in accordance with a predetermined orthogonal trio and able to measure three deformations oriented orthogonally with respect to one another Ev, Er, Ec contained in the undisturbed zone A2, and the tension SYY is proportional to a combination of said three deformation measures oriented orthogonally with respect to one another Ev, Er, Ec. For example, in the hypothesis of axial-symmetrical form both around a portion of the cement agglomerate surrounding the investigation device, and of the investigation device 4 and with a load P applied along an reference axis, the orthogonal trio defined in accordance with the universal vertical, radial and circumferential cylindrical coordinates v, r, c also defines the orientations of the three sensors of vertical, radial and circumferential deformation Rv, Rr, Rc, of the three co-respective vertical, radial and circumferential deformations Ev, Er, Ec and of the three vertical, radial and circumferential tensions Sv, Sr, Sc respectively (see FIG. 5). In addition, in the axial-symmetrical approximation used, the three vertical, radial and circumferential deformations Ev, Er, Ec are different from zero whereas the cutting deformations Erv, Erc, Evc are zero or negligible. This means that the calculation of the axial tension SYY, coincident with the vertical tension Sv, is simplified by applying the resilient linear constitutive bond of the material from which the deformable body 5 is made, in the hypothesis of an axial-symmetrical state according to the following equation (1):

[00001]$\begin{array}{cc}\left\{\begin{array}{c}\mathrm{SXX}\\ \mathrm{SYY}\\ \mathrm{SZZ}\\ \mathrm{SXY}\end{array}\right\}=C\left[\begin{array}{cccc}1-v& v& v& 0\\ v& 1-v& v& 0\\ v& v& 1-v& 0\\ 0& 0& 0& G/C\end{array}\right].Math.\left\{\begin{array}{c}\mathrm{EXX}\\ \mathrm{EYY}\\ \mathrm{EZZ}\\ \mathrm{EXY}\end{array}\right\}& \left(1\right)\end{array}$

[0145] If it is desired to abandon the hypothesis of axial symmetry, it is necessary to apply the full constitutive relation of the material using the six components of deformation and of tension by using a more complex equation, but yielding substantially identical results (see equation (2)).

[00002]$\begin{array}{cc}\left\{\begin{array}{c}\mathrm{SXX}\\ \mathrm{SYY}\\ \mathrm{SZZ}\\ \mathrm{SXY}\\ \mathrm{SXZ}\\ \mathrm{SYZ}\end{array}\right\}=C\left[\begin{array}{cccccc}1-v& v& v& 0& 0& 0\\ v& 1-v& v& 0& 0& 0\\ v& v& 1-v& 0& 0& 0\\ 0& 0& 0& G/C& 0& 0\\ 0& 0& 0& 0& G/C& 0\\ 0& 0& 0& 0& 0& G/C\end{array}\right].Math.\left\{\begin{array}{c}\mathrm{EXX}\\ \mathrm{EYY}\\ \mathrm{EZZ}\\ \mathrm{EXY}\\ \mathrm{EXZ}\\ \mathrm{EYZ}\end{array}\right\}& \left(2\right)\\ .Math.\mathrm{where}.Math.\text{:}& \\ .Math.C=\frac{E}{\left(1+v\right).Math.\left(1-2.Math.v\right)}.Math..Math.G=\frac{E}{2.Math.\left(1+v\right)}& \end{array}$

[0146] where is the Poisson's ratio and E is the Young's modulus.

[0147] Both hypotheses give the equation (3):

Sv=SYY=C[EXX+(1)EYY+EZZ] (3)

[0148] Thanks to the investigation device 4 and the above-mentioned features thereof, even in the case in which the model of the device is not axially symmetrical it is possible to define an undisturbed zone A2, within the deformable body 5, in which the tension Sv is proportional solely to the external actions applied and is not influenced by viscous phenomena produced within the deformable body 5 or by deviations of the force lines (see FIGS. 5 and 6).

[0149] In this case the calculations necessary to obtain the value of the tension require the use of the full constitutive bond of the material from which the deformable body 5 is made, as described above.

[0150] In one preferred embodiment, in the case in which the applied external load P is constant, the above-mentioned combination of the equation 3 is constant and this implies that the value of SYY is also constant.

[0151] The investigation device 4 is preferably fastened to the reinforcement 3 (for example by means of bonding, welding, gluing, etc.).

[0152] In accordance with one embodiment, the deformable body 5 has resilient behaviour, at least with regard to the stresses permissible in said structure of said cement agglomerate.

[0153] The deformable body 5 advantageously comprises two surfaces A, B, the smaller dimension of which is greater than, or equal to, the maximum nominal diameter of a bonded material comprised in said cement agglomerate.

[0154] The deformable body 5 preferably has a substantially flattened shape with regard to two prevalent dimensions so as to obtain inside said deformable body 5 an undisturbed zone A2 of said tension SYY, in which zone said at least one deformation meter Ri is arranged.

[0155] With reference to FIGS. 5 and 6 and as a function of the ratio R between the minimum dimension of the surfaces A and B (also called the base surfaces) and a height h1 of the deformable body 5, the disturbed zone is spatially confined to a more or less extensive portion of the surfaces A and B. Such disturbances, however, only concern an outer cylindrical crown, referred to as A1, of the deformable body 5 for an extension equal to a fraction of the radius (in the case of the cylindrical device shown in FIGS. 5 and 6, such extension is approximately of the radius of the deformable body 5).

[0156] It is therefore possible to identify a zone within the deformable body 5, i.e. said undisturbed zone A2, which remains undisturbed by such viscous phenomena of first and second order and which is therefore subject to a tension Sv=SYY orthogonal to the faces A and B and proportional solely to the agents acting from outside (for example the load P as shown in FIG. 5).

[0157] In particular, the tension Sv=SYY orthogonal to the faces A and B is proportional to a combination of a plurality of deformations comprised in the aforementioned undisturbed zone A2.

[0158] With reference to FIG. 5, the undisturbed zone A2 is preferably identifiable with a cylinder within the deformable body 5, having a base of diameter D2 equal to approximately 20 mm.

[0159] Said at least one deformation meter Ri is preferably positioned at a distance h2 from at least one of said two surfaces A, B (see FIG. 5).

[0160] Furthermore preferably, the distance h2 is greater than, or equal to, the dimension of the larger gas bubble possibly present in the agglomerate. In fact, such a positioning of the aforementioned deformation meter R1 allows the material from which the deformable body 5 is made to reduce the local disturbance caused to the measurement by the gas bubbles present in the agglomerate.

[0161] In accordance with one embodiment, the deformation meter Ri is disposed equidistantly between the two faces A and B.

[0162] The deformation meter Ri is alternatively disposed asymmetrically within said deformable body, but maintaining the minimum distance between a part thereof and the face A or B greater than said dimension of the larger gas bubble.

[0163] With reference to FIG. 2 the pre-cast segment 1 preferably comprises a first, a second and a third investigation device 4a, 4b, 4c respectively placed in opposite radial faces 2a, 2b, 2c and in a medial zone M of the arcuate structure 2.

[0164] The first, second and third investigation devices 4a, 4b, 4c are preferably arranged along a radial alignment with the longitudinal axis X of the tunnel, and the first and second device are substantially parallel to the respective radial face in which they are housed.

[0165] The first, second and third investigation devices 4a, 4b, 4c are advantageously pluralities of investigation devices housed respectively in opposite radial faces 2a, 2b and in the medial zone M of the arcuate structure 2.

[0166] In accordance with one embodiment the investigation device 4, the first, the second or the third investigation device 4a, 4b, 4c, are operatively connected to a processing unit 50 that is capable of processing the data collected by said investigation devices. This operative connection can be established by means of cables (preferably equipped with watertight connectors) or by means of wireless data transfer systems.

[0167] Furthermore, the investigation device and/or the processing unit can be powered by means of a battery or by means of an electrical connection to an external power supply line.

[0168] Such connections are established by means of cables and connectors guaranteed in accordance with standard IP68 and satisfying the ATEX parameters.

[0169] The pre-cast segment 1 preferably comprises at least one capacitive sensor 10, included in the arcuate structure 2, for detecting internal fractures of the pre-cast segment 1.

[0170] Persons skilled in the art will be able to identify the type of capacitive sensors available on the market that can be best applied for the needs of the present invention.

[0171] In accordance with one preferred embodiment, the capacitive sensor 10 is operatively connected to the processing unit 50 that is capable of processing the data from said sensor. This operative connection can be established by means of cables (preferably equipped with watertight connectors) or by means of wireless data transfer systems.

[0172] Furthermore, the capacitive sensor and/or the processing unit can be powered by means of a battery or by means of an electrical connection to an external power supply line.

[0173] In accordance with one embodiment, the at least one capacitive sensor 10 is housed in a resting zone S1 identified on a circumferential face 2c, 2d or on the inner longitudinal face 2e usable by a tunnel boring machine to rest against during a movement phase.

[0174] The at least one capacitive sensor 10 is preferably housed within the arcuate structure at a distance F (not shown in the drawings) from the inner longitudinal face 2e equal to approximately half the pitch between two consecutive positioning zones S1, S2 of two contact jacks of said tunnel boring machine.

[0175] The applicant has in fact demonstrated that applications of loads from the tunnel boring machine aimed at producing the movement by means of resting on said surfaces of a circumferential face 2c, 2d or on the inner longitudinal face 2e can induce phenomena of fracturing within the segment itself and in particular at the jacks of the tunnel boring machine used as bearing points. In accordance with one embodiment, the step between the two positioning zones S1, S2 is around 1.20 m, and therefore the distance F is equal to approximately 0.60 m.

[0176] In accordance with one embodiment, the pre-cast segment 1 comprises at least one inclinometer 20 arranged in or on the arcuate structure 2 and configured to detect variations of ovalisation of the pre-cast segment 1.

[0177] The inclinometer 20 preferably comprises a watertight box inside which there is housed an inclination sensor.

[0178] The inclinometer 20 is advantageously fastened from the outside to the arcuate structure 2 by means of a bracket or similar technical solutions advantageously making it possible to fix said inclinometer with a preferred orientation.

[0179] In accordance with one embodiment, the inclinometer 20 is constrained to the inner longitudinal face 2e, which extends towards the interior of the tunnel.

[0180] Persons skilled in the art will be able to identify the type of inclinometer available on the market that can be best applied to the needs of the present invention.

[0181] In accordance with one preferred embodiment, the inclinometer 20 is operatively connected to the processing unit 50 able to process the data received from said inclinometer. This operative connection can be established by means of cables (preferably equipped with watertight connectors) or by means of wireless data transfer systems.

[0182] Furthermore, the inclinometer 20 and/or the processing unit can be powered by means of a battery or by means of an electrical connection to an external power supply line.

[0183] The pre-cast segment 1 preferably comprises a first plurality of transverse inclinometers 21 operatively interconnected and housed with a predefined step along a direction transverse to the longitudinal axis X and/or a second plurality of longitudinal inclinometers 22 operatively interconnected and housed with a predefined step along a direction parallel to said longitudinal axis X.

[0184] In accordance with one embodiment, the first plurality of transverse inclinometers 21 or the second plurality of longitudinal inclinometers 22 are positioned in or on a flexible strip.

[0185] The inventive product produced in accordance with the present invention is a tunnel ring 100 comprising at least five pre-cast segments, which are moved towards one another in twos, on the respective opposite radial faces 2a, 2b for forming a ring, at least three of the pre-cast segments being formed as said pre-cast segment 1 that is designed to cover structurally repeated annular tunnel segments for modules corresponding to a fraction of the cross section thereof. The arcuate structure 2 comprises respective opposite radial faces 2a, 2b that lie on surfaces radial with respect to the longitudinal axis X of the tunnel, respective opposite circumferential faces 2c, 2d that lie on surfaces perpendicular to the longitudinal axis X, and respective opposite longitudinal 2e, 2f faces that lie on surfaces that are parallel to the longitudinal axis X. The radial faces 2a, 2b are advantageously moved towards respective radial faces of adjacent segments in order to form an annular tunnel portion, said circumferential faces 2c, 2d being adapted to be moved towards one another in order to form a linear extent of said tunnel along said longitudinal axis X and an outer longitudinal face 2f being at a greater distance than an inner longitudinal face 2e from said longitudinal axis X, placed in contact with the ground of said tunnel, wherein at least one investigation device 4 is embedded in said arcuate structure 2 of said pre-cast segment 1 at a predetermined distance D from at least one of said radial 2a, 2b, circumferential 2c, 2d or longitudinal 2e, 2f faces.

[0186] The operating modes of the pre-cast segment, defining the process and method of the present invention, comprises the steps described hereinafter.

[0187] The process 200 for producing and monitoring a pre-cast segment 1 made of cement preferably comprises providing formwork for receiving a concrete cast, housing at least one investigation device 4 in said formwork, operatively connecting said at least one investigation device 4 to a processing unit 50 that is capable of processing the data collected by said at least one investigation device 4, carrying out said concrete casting inside said formwork by embedding said at least one investigation device 4 to form an arcuate structure 2 of said pre-cast segment 1, and monitoring the data processed by said processing unit 50 by analysing any changes in said collected or processed data during the steps following said concrete casting.

[0188] In this context, the term cement means both the structures in reinforced concrete (and therefore equipped with reinforcement) and reinforced concretes (and therefore comprising metal or ceramic fibres therewithin capable of increasing the mechanical characteristics of the concrete itself).

[0189] The process 200 of producing and monitoring a pre-cast segment 1 made of reinforced concrete preferably comprises: providing a reinforcement 3 within formwork for receiving a concrete cast, fastening at least one investigation device 4 to the reinforcement 3, operatively connecting the at least one investigation device 4 to a processing unit 50 that is capable of processing the data collected by the at least one investigation device 4, carrying out said concrete casting inside said formwork by embedding the reinforcement 3 and the at least one investigation device 4 to form an arcuate structure 2 of the pre-cast segment 1, and monitoring the data processed by said processing unit 50 by analysing any tension changes during the steps following said concrete casting.

[0190] The production and monitoring process 200 preferably comprises: constraining at least one capacitive sensor 10 to a support or to the reinforcement 3 before carrying out said concrete casting, operatively connecting the at least one capacitive sensor 10 to the processing unit 50 capable of processing the data collected by said at least one capacitive sensor 10, and monitoring the data processed by said processing unit 50 by analysing any structural changes detected by said at least one capacitive sensor 10 during the steps following said concrete casting.

[0191] In accordance with one embodiment, the production and monitoring process 200 comprises constraining at least one inclinometer 20 to the outside of said arcuate structure 2 after a predefined curing time Tc from when the concrete casting took place, operatively connecting said at least one inclinometer 20 to said processing unit 50 that is capable of processing the data collected by said at least one inclinometer 20, and monitoring the data collected or processed by said processing unit 50 by analysing any changes of inclination detected by said at least one inclinometer 20 during the steps following said concrete casting.

[0192] The curing time Tc is preferably comprised within the period of 8 weeks.

[0193] In accordance with one embodiment, the production and monitoring process 200 comprises: waiting during said curing time Tc of the arcuate structure 2 of the pre-cast segment 1, installing the pre-cast segment 1 inside a tunnel, and monitoring the data processed by said processing unit 50 by analysing any structural changes detected.

[0194] The method 300 for producing and monitoring a tunnel preferably comprises: making a hole in a terrain, installing pre-cast segments on opposite radial faces 2a, 2b by moving them towards one another in twos, so as to form a tunnel ring, at least one of said pre-cast segments comprising an investigation device 4 such that, once connected to a processing unit 50, the processed data can be monitored during and after the installation of said pre-cast segments in said tunnel.

[0195] In accordance with one embodiment, the method 300 comprises using a tunnel boring machine to make the hole for the tunnel and to install the pre-cast segments, at least one of said pre-cast segments 1 comprising an investigation device 4.

[0196] The investigation device 4 is then connected to a processing unit 5 by advancing said tunnel boring machine so that it touches said pre-cast segments, at least one of said pre-cast segments 1 comprising said investigation device 4, and monitoring the data processed during and after the installation of the pre-cast segments in said tunnel. The data operatively transferred from the investigation device 4 and processed by the processing unit 5 is of the ASCII or raw type or the like, allowing said data to be processed and displayed by said processing unit in accordance with force/deformation ratio models or the like, known within the field of study of cement structures.

[0197] In accordance with one embodiment the tunnel boring machine is moved along the tunnel, pushing on a bearing or positioning zone of jacks identified on a circumferential face 2c, 2d or on the inner longitudinal face 2e of the aforementioned pre-cast segment 1.

[0198] The method 300 preferably comprises advancing the tunnel boring machine along a longitudinal axis X of the tunnel by resting it against at least one pre-cast segment 1 and monitoring any changes in the data processed during and after the resting phases of the tunnel boring machine.

[0199] In this way, it is possible to evaluate, in real time, any changes in structural responses provided by the pre-cast segment 1 as a result of the formation of fracturing, cracks or deformations.