ES2424396A1 - Device for continuous measurement of convergence in tunnels (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Device for continuous measurement of convergence in tunnels by measuring angles and displacements of a perimeter cable (2) anchored at one end and passing through a series of control points pi. At each control point there is a measurement module (1) consisting of an incremental digital encoder a (5) and two incremental digital encoders b (7) and c (8). The angles measured by them are recorded by an electrical measuring circuit (13) and digitally recorded in an electrical storage circuit (14). From these measurements, the position of the control points in a coordinate system is determined at each instant of time. The invention is applicable in those sectors where tunnels are designed, excavated or used, such as underground mining, civil works, transport, security and underground road control. (Machine-translation by Google Translate, not legally binding)

Description

DEVICE FOR CONTINUOUS MEASUREMENT OF THE CONVERGENCE

IN TUNNELS

The present invention relates to an electromechanical measuring system that detects the movements of the walls of a tunnel by measuring angles and displacements of a perimeter cable that passes through a series of control points anchored in said walls. These measurements are made by incremental digital encoders that are activated by the movement of a perimeter cable that passes through the control points. The measurements taken allow the continuous coordinates of each control point to be calculated in relation to a reference coordinate system. The system allows to determine the convergence of the tunnel from the variation of coordinates of each control point as a function of time.

The invention is applicable in those sectors in which tunnels are designed, excavated or used, such as underground mining, civil works, transportation, security and control of underground roads.

STATE OF THE TECHNIQUE

The measurement of convergences in tunnels is essential to control possible unexpected behavior of the terrain or of the support, providing the technician with a tool to prevent possible accidents. The ideal is to have control systems that allow continuous recording over time, capable of detecting phenomena such as land settlements, effects of blasting or structural failures of support elements. Also, the continued measurement of this convergence is the best way to verify that the tunnel support works correctly.

The convergence measurement is carried out in different sections of the tunnel, conveniently spaced, measuring the position of significant points arranged on the perimeter of the tunnel, called control points. To perform these measurements, mechanical or optical systems can be used to record changes in diametric or perimeter quantities in the tunnel.

Among the most commonly used mechanical methods to control the variation of the perimeter of the tunnel are the distance bands (distometer). They are very precise equipment, with uncertainties between 0.003 mm and 0.1 mm. Examples of these systems can be found in: Kovari K, Arnstad C, Grob H. "Measurement of Displacements and Deformation in Civil Engineering Works by the DistometerISETH Gage". Schweiz Bauztg 1974; 92 (36): 819-825; Martin CD, Chandler NA, Read RS. "The role of convergence measurements in characterizing a rock mass". Canadian Geotechnical Joumal, 1996; 33: (2) 363-370; Martinet A. "Study of and checks on the stability of the underground hydroelectric power station at Le Verney", ISRM Intemational Symposium, Aachen, Germany; 1982, 3p .; or in Simeoni L, Zanei

1. "A methodfor estimating the accuracy of tunnel convergence measurements using tape distometers". Intemational Joumal of Rock Mechanics & Mining Sciences, 2008; 46: 796-802. All of them use invar cables as a deformation transmission element. The main drawback of all these systems is that they only allow displacement between two points, usually located transversely, which prevents the continuous recording of the measurements. Another drawback of these measurement systems is that they partially occupy the tunnel section, interfering with the work of the machinery and the transfer of the operators.

Other mechanical systems for measuring convergence in tunnels, although much less used than distometers, are strain gauges. In reality, these systems are usually used in isolated points of the tunnels as a complement to the measurements made by distometers or other convergence measurement methods. The strain gauges have the disadvantage that their installation offers many difficulties in humid environments, with the presence of dust or air pollution. On the other hand, measurement stops occur as a result of the replacement of the gauges over time, especially when large deformations occur on the ground.

Among the mechanical methods are also known those that have a perimeter cable anchored by bolts to the perimeter of the tunnel, such as that of the

Patent ES 2380256 (B2), where one end of the cable is fixed and the other is attached to a counterweight that moves and indicates the axial displacement of the cable. However, in this type of systems, only data of the axial displacement of the entire length of the cable can be collected, but information on localized displacements and the relationship between the relative movements at the different cable fixing points to the contour of the cable cannot be extracted tunnel.

Among the optical systems are topographic equipment, primarily robotic total stations (Klopcic J, Ambrozic T, MaIjetic A, Bogatin S, Pulko B, Winery J. "Use of Automatic Target Recognition System for the Displacement Measurements in a Small Diameter Tunnel Ahead of the Face of the Motorway Tunnel During Excavation. "Sensors, 2008; 8: 8139-8155). These devices are installed on one side of the tunnel so as not to interfere with the activity in the tunnel and automatically measure angles and distances. Their main advantage is that they can take measurements automatically over long distances, depending on the geometry of the tunnel. On the contrary, they have the disadvantage that they do not carry out continuous measurements and are less accurate than distometers. In addition, it is necessary to subject them to maintenance operations, given the environmental conditions in the tunnels.

Other optical systems, although less used, are profilometers (Barragan A, Cembrero P, Caceres N, Schubert F. "Automated and Cost Effective Maintenance for Railway. D2.1 Report on railway inspection and monitoring techniques -Analysis of different approaches". Seventh framework program theme sst. 2010.5.2.1. Contract: 265954.), photogrammetric restitution systems (S.Miura, S.Hattori, K. Akimoto and y'Ohnishi, "Tunnel converge ce measurement using vision metrology", Modern Tunneling Science and Technology, Adachi et al., Vol 1, 265-268, Balkema, Kyoto, 2001) or, more recently, laser scanners (Schroedel J. "Engineering and Design Structural Deformation Surveying". US Arrny Corps of Engineers. EM 11102-1009; 2002, 292 p.). These devices are generally more expensive and less accurate than distometers. In addition, in some cases the intervention of one or more operators is necessary, and they do not carry out measurements continuously. On the contrary, with the same equipment you can measure as many sections as you want, although it is necessary to change it according to the variations in the direction in the tunnel.

DESCRIPTION OF THE INVENTION

The present invention relates to an electromechanical device for measuring convergence in tunnels

It is based on the continuous recording of the movement of a perimeter cable that is anchored to the hastia! Es and crown of the tunnel. When there is a movement of the ground and the consequent displacement of the control points where the perimeter cable is anchored, a set of incremental digital sensors of angular measurement (digital eneoders increase!) And the mechanical system devised, allow to determine the angles that each Perimeter cable portion! with the anterior and posterior section, as well as the axial displacement of the perimeter cable! From the measured angles it is possible to determine the position of each control point in the space, and measure the convergence of the tunnel continuously, without having to interrupt the work or traffic of vehicles through the tunnel.

The system is therefore based on the measurement of an open polygonal materialized by a perimeter cable! which is subject to the perimeter of the tunnel at a series of control points.

The object of this invention is a device for continuous measurement of convergence in tunnels comprising:

A perimeter cable! with one end fixed to a patella that maintains its position with respect to one point of the tunnel wall and the other end attached to a dead weight that puts it under tension, which passes through two or more control points Pi fixed to the wall of the tunnel.

A measurement module at each control point Pi comprising an incremental digital eneoder A associated with a glutton pulley on which the perimeter cable passes! and that records the axia displacement! of the perimeter cable at every moment t. The incremental digital eneoder A records the angle Oi that corresponds to! Angle that rotates the guide pulley associated with it when the perimeter cable moves over it! and that translates into the longitudinal displacement of the cable with respect to! check Point. Each measuring module also comprises a probe in contact with the surface of the perimeter cable associated with an incremental digital encoder B and another probe in contact with the surface of the perimeter cable associated with another incremental digital encoder C. Both the incremental digital encoder B and the digital encoder

incremental C record the angles ai and Pi formed by the perimeter wire at each control point Pi at each moment t.

Data acquisition means of the incremental digital encoder A, the incremental digital encoder B and the incremental digital encoder C.

In a preferred embodiment, the ball joint to which one end of the cable is fixed is the guide pulley of the measuring module located at the first control point P l. Thus, for example, at the first PI control point the perimeter cable is supported on the guide pulley by means of a ring, so that it allows the cable to rotate but not to move.

In another preferred embodiment, the incremental digital encoder A is solid shaft, and the incremental digital encoder B and the incremental digital encoder C are hollow shaft. This allows a more compact design, leaving sufficient freedom of movement of the perimeter cable and the probes, and improving the response of the measurement module to the mechanical stresses made by the perimeter cable in tension on the guide pulley.

In another preferred embodiment, the perimeter wire is made of invar or of a carbon steel alloy.

In another preferred embodiment the dead weight attached to the other end of the cable and which gives it tension is a steel cylinder.

In a specific embodiment, the angle recorded by the digital encoder

incremental ai B and the incremental digital encoder C is the angle formed by the input and output sections of the perimeter cable at each control point Pi.

In another specific embodiment, the angle Pi recorded by the incremental digital encoder C is the angle formed by the vertical and the section of the perimeter wire at each control point Pi.

In another specific embodiment, the probes associated with the digital encoders In the measurement module of the PI control point, since the perimeter cable does not have the

incrementals B and C comprise a rod with an end associated with a pulley that

is in contact with the surface of the perimeter cable and with the other end attached

respectively to incremental digital encoder B or incremental digital encoder C.

s

The perimeter wire is placed along a cross section of the tunnel,

supported on the guide pulley at each control point. At each control point it is placed

a measuring module anchored to the tunnel walls, for example by means of a bolt.

As the terrain moves, each control point moves and this results in a

movement that is transmitted to the guide pulleys on which the perimeter cable rests.

10

The cable is supported on these pulleys, being able to move axially and making

turning said pulley guides an angle ti. In addition, when changing the shape of the polygonal

perimeter that constitutes the cable at one or several control points, the palpated res

located in the measurement modules also transmit angular information to the

incremental digital encoders B and C inside. In any case, the end

lS

initial perimeter cable is considered fixed in displacements, allowing

only the rotation of the perimeter cable by using a ball joint that

It is preferably a guide pulley. At the other end of the perimeter cable a

deadweight whose objective is to gravity tighten the perimeter wire and prevent

exit the pulley guides.

twenty

Each guide pulley is integral with the axis of an incremental digital encoder

A to measure its angle of rotation ti, and from it determine the displacements

axial perimeter wire. In addition, it incorporates two incremental digital encoders

B and C to measure the angle formed by the perimeter wire at each control point of

the polygonal. Each of these two incremental digital encoders B and C is operated

2S

by a probe, preferably mechanical, supported by the perimeter cable so

which allow to control the position of the perimeter cable at the entrance and exit of

Each control point. Preferably, each probe is connected to the digital encoder

respective incremental B or C using a steel rod and rests on the cable

perimeter according to a pulley that rotates freely to ensure correct contact

30

between the probe and the perimeter wire.

input section but only the output, only the incremental digital eneoder e.

In another specific embodiment, each measurement module is protected by a box that has two grooves at its lateral ends through which the perimeter cable enters and exits the guide pulley located in the center of the box, allowing its angle to vary of entry and exit. In addition, the box has a perforated angular plate to allow the passage of an anchor bolt that anchors the measuring module to the tunnel walls.

In a preferred embodiment, the data acquisition means of the incremental digital eneoder A, the incremental digital eneoder B and the incremental digital eneoder comprise a measurement circuit located in the measurement module of each control point Pi and a storage circuit which connects to each measurement circuit.

The angular measurements are transformed analytically to obtain at each moment t the positions of the control points in a system of Cartesian axes (x, y) defined in each section.

The system also has a storage circuit outside the measurement module that reads the measured values at each control point Pi and records them digitally for further processing on an industrial personal computer.

In a more preferred embodiment, the electrical measuring circuit comprises a PIe (Peripheral Interface Control / er) microprocessor that continuously records the movements detected by the incremental digital eneoder A, the incremental digital eneoder B and the incremental digital eneoder e.

In another more preferred embodiment, the electric measuring circuit comprises an alarm system with alarm means indicating the status of the incremental digital eneoder A, the incremental digital eneoder B and the incremental digital eneoder e, as well as the anomalous displacement in the tunnel walls when a certain convergence threshold is exceeded. In an even more preferred embodiment, the alarm means are bright, although other types of alarm means such as acoustic signals with appropriate modifications could also be more generically, if necessary. In an even more preferred embodiment, the light indicating means is LED.

In another more preferred embodiment, the electrical storage circuit comprises a PIe microprocessor and a memory card that allows the values measured at the control points Pi for each measurement module to be recorded in regular periods of time.

The device proposed here is a continuous and autonomous measurement system. It does not require the continuous supervision of an operator to estimate the convergence values, and does not constitute an obstacle that prevents normal movement within the tunnel, favoring both the access of personnel with the transfer of materials within the tunnel, especially in the phase of excavation of it. It also allows to obtain the position of each control point as a function of time and not only measures what a cable is shortened, either perimetral or diametral, as do other mechanical measurement systems. The measurements can be carried out in the presence of water or in heavily polluted atmospheres, not being as affected as with the optical measurement systems, which require a well-defined visibility. The proposed device works better than other systems in tunnels where vibrations derived from explosions, smoke and dust pollution, or large landslides occur. Even large deformations and failures of the tunnel could be recorded, as long as these do not affect the perimeter cable and the anchorage of the measurement units. This is not possible using strain gauges, especially when large deformations occur and the gauges need to be replaced, or when humidity or vibration conditions make their use unfeasible.

The invention is applicable in those sectors where tunnels are designed, excavated, or used, such as underground mining, civil works, transportation, security and control of underground roads.

DESCRIPTION OF THE FIGURES

Fig. 1 represents an elevation view of the measuring device. It clearly shows five control points Pi where the measurement modules (1) are anchored, the perimeter cable! (2), the ball joint located at the control point p¡ (3) and the dead weight (4) for tensioning the perimeter cable (2) located at the control point Ps. In this figure only five control points are considered, although for tunnels with large sections the number of control points Pi can be increased, adding more measurement modules (1) along the tunnel wall.

Fig. 2 shows the basic elements of the measurement module (1) at each control point Pi and the angles a, and p, recorded at each control point Pi. A detail of one of the areas indicated in Fig. 1 in which the basic elements of a measuring module (1) can be seen is shown in Fig. 2A. It consists of an incremental digital eneoder A (5) and two incremental digital eneoders B (7) and C (8), which allow the registration of the angles formed by the perimeter cable at each control point Pi and at each time t. The digital eneoder! incremental A (5) measures the angle 0, of rotation of the guide pulley (6) on which the perimeter cable rests! (2); This angle of rotation makes it possible to determine the axial displacement of the perimeter wire! The incremental digital eneoders B (7) and C (8) are driven by two parents (9) and (10). Depending on the position of these pins (9) and (10), the angles a, Yp, are determined. The angle a, is the angle formed by the input and output sections

of the perimeter cable! (2) at each control point Pi. The angle p, is the angle that forms the vertical and the exit section of the perimeter cable! (2) at each control point Pi. Fig. 2B shows the angles a, and p, which are measured by five measuring modules (1) located at the control points Pi. From the angles at "p, and 0, the lengths of each section of perimeter cable! Li, and the coordinates of

each control point Pi in a Cartesian coordinate system (x, y).

Several detailed dihedral views of each of the elements of the measurement module (1) are shown in Fig. 3. In Fig. 3A the elevation and the plan are shown with the arrangement of each of the elements:

-

Digital eneoder increases! A (5), - incremental digital encoder B (7),

-

incremental digital encoder e (8),

-

guide pulley (6) attached to the axis of the incremental digital encoder A (5),

-

probe (9) of the incremental digital encoder B (7),

-

probe (10) of the incremental digital encoder e (8),

-

angular plate (12) for attachment to the anchor bolt,

-

openings (11) that allow the entry and exit of the perimeter cable (2).

Figure 3B shows the main view and profile of the incremental digital encoders A (5) and B (7). The incremental digital encoder e (8) is symmetrical to the incremental digital encoder B (7) represented in this figure. Fig. 3C represents an elevation view and the side view of the guide pulley (6), a view and the cutting of the probes (9), as well as the dihedral views of the angular plate (12) associated with the box for anchor it. The probe (10) is identical to the probe (9) represented in this figure.

Fig. 4 shows the arrangement of the electrical and electronic elements of the device. Data recorded by incremental digital encoders A (5), B (7)

or e (8) at each moment t are controlled by two electrical circuits called electrical measurement circuit (13) and electrical storage circuit (14). The electrical measuring circuit (13) is basically made up of a bakelite plate with the circuit printed with the PIe microprocessor (17) and the wiring that allows connecting the incremental digital encoders A (5), B (7) and e (8 ) to a stabilized power supply (16). This electrical measuring circuit (13) connects the incremental digital encoder A (5), the incremental digital encoder B (7) and the incremental digital encoder e (8), to an alarm system (18) consisting of six LEDs (Light Emitting Diodes) Ll, L2, L3, 14, L5 and L6, which allow to visualize the error and activity conditions of the incremental digital encoder A (5), the incremental digital encoder B (7) and the incremental digital encoder e (8 ). This electrical measuring circuit (13) also has an adapter system for the TTL (Transistor-Transistor Logic) communication signals generated by the processor to signals compatible with the RS485 protocol used to communicate the measurement circuit with the storage circuit. The electrical storage circuit (14) is located outside the measurement module, allows as many inputs as Pi control points have been used and is based on a PIC microprocessor (19) that allows registration in a memory card (20), in regular periods of time, the values measured at the control points Pi before being analyzed, for example, in an industrial personal computer (15).

EXPLANATION OF A PREFERRED EMBODIMENT

For a better understanding of the present invention, the following preferred embodiment example, described in detail, which should be understood without limitation of the scope of the invention is set forth.

The components of the measurement module (1) materialized inside a 200 x 150 x 75 mm box, with two lateral grooves (11) to allow the perimeter cable (2) to pass through. Said box was fixed to the tunnel wall by means of a steel bolt and the angular plate (12).

The perimeter cable (2) that links the control points Pi made of 3 mm diameter invar, although it can be replaced by another type of carbon steel or another material that resists tensile and flexural stresses. The deadweight (4) for tensioning the perimeter wire (2) was formed by a 4 kg steel cylinder.

In each measuring module (1) a steel guide pulley (6) was used, preferably 8 mm in diameter, which operated the incremental digital encoder A (5).

The incremental digital encoder A (5) was solid axis, while the incremental digital encoders B (7) and C (8) were hollow axis.

The rod that joins the probe (9) and the incremental digital encoder A (7) And the rod that joins the probe (10) and the incremental digital encoder C (8) were made of steel, with a variable length depending on the range of angular values that should be measured.

In the electrical measuring circuit (13) JUMPER type connectors were arranged for the connection of the incremental digital encoder A (5), the incremental digital encoder B (7) and the incremental digital encoder e, and an alarm system (18) formed by six LEDs: Ll power indicator, L2 was lit every time it measured the incremental digital encoder A (5), L3 lit every time it measured the incremental digital encoder B (7), L4 lit every time it measured the Incremental digital encoder e (8), L5 was turned on to indicate that the electronic measurement circuit (13) was transmitting data to the electrical storage circuit (14) and L6 to signal possible displacements above a safety threshold.

The electrical measuring circuit (13) was supplied with a voltage between 8V and 24V through an electrical stabilization circuit. It also had a RESET circuit, operated by a button, which initialized the PIe microprocessor (17) if necessary, and an IeSp circuit (In eircuit Serial Prograrnming) that allowed programming the microprocessor already mounted on the board.

A PIe microprocessor (17) was responsible for continuously recording and processing the measurements of the incremental digital encoder A (5), the incremental digital encoder B (7) and the incremental digital encoder e (8) within each measurement module ( one). The electrical measuring circuit (13) also had an adapter circuit of the TTL communication signals generated by the processor to signals compatible with the RS485 protocol, used to communicate with the storage circuit (14)

The storage circuit (14) took with a PIe microprocessor (19), at programmed intervals, the reading of the measurement modules (13) and stored the records on a non-volatile memory card (20). It is also responsible for providing such data to an industrial personal computer (15), when connected via an RS485 port.

Claims (13)

1. Device for continuous measurement of convergence in tunnels comprising: a perimeter cable (2) with one end fixed to a kneecap (3) that maintains its position with respect to one point of the tunnel wall and the other attached to a dead weight (4) that puts it under tension, which passes through two or more control points Pi fixed to the tunnel wall; a measuring module (1) at each control point Pi comprising an incremental digital encoder A (5) associated with a guide pulley (6) over which the perimeter cable (2) that registers the axial displacement of the perimeter cable ( 2) at each moment t, a probe (9) in contact with the surface of the perimeter cable (2) associated with an incremental digital encoder B (7) and a probe (10) in contact with the surface of the perimeter cable (2) associated with an incremental digital encoder e (8) that record the angles ai and Pi formed by the perimeter cable (2) in each control point Pi at each instant t; data acquisition means of the incremental digital encoder A (5), the incremental digital encoder B (7) and the incremental digital encoder e (8).

2.

Device according to claim 1, characterized in that the ball joint (3) is the guide pulley (6) of the measuring module (1) located at the first control point PI.

3.

Device according to claim 1 characterized in that the incremental digital encoder A (5) is of solid axis, and the incremental digital encoder B (7) and the incremental digital encoder e (8) are hollow axis.

Four.

Device according to claim 1 characterized in that the perimeter cable

(2) It is from Invar or a carbon steel alloy.

5.

Device according to claim 1 or 4 characterized in that the dead weight

(4) is a steel cylinder.

6.

Device according to claim 1 characterized in that the angle

ai records the incremental digital eneoder B (7) and the incremental digital eneoder e (8) is the angle formed by the input and output sections of the perimeter cable (2) at each control point Pi.

7.

Device according to claim 1 characterized in that the angle Pi that registers the incremental digital eneoder e (8) is the angle formed by the vertical and the output section of the perimeter cable (2) at each control point Pi.

8.

Device according to claim 1 characterized in that the probes (9) and

(10) comprise a rod with one end associated with a pulley that is in contact with the surface of the perimeter cable (2) and with the other end connected respectively to the incremental digital eneoder B (7) or to the incremental digital eneoder e (8) .

9.

Device according to claim 1 characterized in that the data acquisition means of the incremental digital eneoder A (5), of the incremental digital eneoder B (7) and of the incremental digital eneoder e (8) comprise a measuring circuit (13) located in the measurement module (1) of each control point Pi and a storage circuit (14) that is connected to each measurement circuit (13).

10.

Device according to claim 9 characterized in that the electric measuring circuit (13) comprises a microprocessor PIe (17) that continuously records the movements detected by the incremental digital eneoder A (5), the incremental digital eneoder B (7) Y the incremental digital eneoder e (8).

eleven.

Device according to claim 9 or 10, characterized in that the electric measuring circuit (13) comprises an alarm system (18) with alarm means indicating the status of the incremental digital eneoder A, the incremental digital eneoder B and the digital eneoder incremental e as well as the

anomalous displacement in the tunnel walls when a certain convergence threshold is exceeded. 12. Device according to claim II characterized in that the alarm means are luminous. A device according to claim 12 characterized in that the luminous alarm means are LED. 14. Device according to claim 9 characterized in that the electrical storage circuit (14) comprises a PIe microprocessor (19) and a memory card (20) which allows the user to register, at regular periods of time, the 10 values measured at the Pi control points for each measurement module (1).