WO2014082105A2

WO2014082105A2 - A rock movement monitoring system

Info

Publication number: WO2014082105A2
Application number: PCT/ZA2013/000089
Authority: WO
Inventors: Ian Gebbie; Christiaan Jozef BOSCH; David Charles Tyrer; Adriaan Jakobus Jacobs
Original assignee: Ncm Innovations (Pty) Ltd
Priority date: 2012-11-20
Filing date: 2013-11-20
Publication date: 2014-05-30
Also published as: ZA201501588B; WO2014082105A3; AU2013101721A4

Abstract

The invention provides a system for monitoring movement of a rock face which includes: - a plurality of sensors, each of which is adapted to detect movement of the rock face and, on detection of rock movement, to generate a signal; - a receiver for receiving signals generated by the sensors; - a communication link which links each of the sensors to the receiver and along which a signal is transmitted to the receiver; and - an warning device which is actuable to generate an alarm response to at least are signal received by the receiver.

Description

A ROCK MOVEMENT MONITORING SYSTEM

BACKGROUND OF THE INVENTION

[0001] This invention relates to a system and method for detecting and monitoring movement of a rock face in an excavation and, more particularly, to detecting rock strata separation in the rock face of the excavation to forewarn workers in the excavation of the possibility of rock fall.

[0002] Although a sidewall is capable of collapse or partial disintegration as a rock strata separation behind the face, the hanging wall potentially poses the most severe danger.

[0003] An excavation, and more particularly an underground tunnel or mine working, can extend for many kilometres and can be convoluted, bending and turning, and therefore not providing a direct line of sight along its length.

[0004] In such an excavation, although there may be a number of rock movement detection indicators, which may be of the type described in the specification to patent application ZA2010/01315 (the specification to which is here incorporated by reference, which is hereinafter referred to as the prior specification), installed along its length in the hanging wall, many of these indicators will be out of the line of sight, or earshot, of a worker who is entering the excavation from a safe area. Thus, the worker does not know if, at any point along the excavation's length, there has been movement of the hanging wall (closure of the excavation) and therefore is unaware of a potential danger. This danger will only present itself when the worker leaves the area of relative safety and enters the excavation. [0005] The present invention at least partially addresses the aforementioned problem.

SUMMARY OF INVENTION

[0006] The invention provides a system for monitoring movement of a rock face which includes:

- a plurality of sensors, each of which is adapted to detect movement of the rock face and, on detection of rock movement, to generate a signal;

- a receiver for receiving signals generated by the sensors;

- a communication link which links each of the sensors to the receiver and along which a signal is transmitted to the receiver; and

- an warning device which is actuable to generate an alarm response to at least are signal received by the receiver.

[0007] Each sensor may generate a signal based on the identity of the sensor or the magnitude of movement of the rock face, or both.

[0008] The sensors may be individually powered, alternatively powered from a remote power source via a power line.

[0009] Each sensor may be engaged with the rock face, for example a hanging wall, and may be part of a rock movement device as described in the prior specification. Alternatively, each sensor may be of a type that has an elongate body that extends between a hanging and an opposed foot wall to detect closure between the hanging and the foot walls. [0010] The system may include a logic device which receives input from the receiver based on signals received by the receiver and generates an output response.

[0011] The output response may be actuation of the warning device to generate the alarm response when the magnitude of rock face movement, at one or more locations, exceeds a predetermined level.

[0012] The logic device may be programmable to identify and communicate the origin of each signal.

[0013] The logic device may be programmable to initiate periodic polling signals addressed to one or more of the sensors and to identify and communicate the origin of a response to these polling signals.

[0014] The communication link may be a serial communication link or a parallel communication link.

[0015] The communication link may be established over a conductive, a fibre-optic or a wireless link.

[0016] The conductive communication link may be the power line.

[0017] The invention extends to a method for detecting movement of a rock face of an excavation which includes the steps of:

(a) providing a plurality of rock movement sensors, each of which is adapted to detect movement of the rock face and, on detection of movement to the rock face, to generate a signal;

(b) engaging the plurality of sensors with the rock face at spaced intervals; (c) providing a central control unit remote from the sensors which includes an alarm device;

(d) linking each sensor to the control unit, by means of a communication link, to provide communication between each sensor and the control unit; (e) sending a signal, generated by a sensor in response to movement of the rock face, along the communication link to the control unit; and

(f) generating an alarm response on receipt of the signal by the control unit.

[0018] The sensors may be linked to the control unit in series or in parallel.

[0019] The sensors and the control unit may be physically linked or wirelessly linked.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention is further described by way of examples with reference to the accompanying drawings in which:

Figure 1 is a schematic diagram of a first embodiment of a system for detecting and monitoring movement or a rock face according to the invention;

Figure 2 is a block circuit diagram of the system of the first embodiment; and

Figure 3 is a block circuit diagram of a second embodiment of the system of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] In a first embodiment of the invention, a system for monitoring movement of a rock face of an excavation 10A, is described with reference to Figures 1 and 2. In this embodiment a plurality of rock movement sensors, respectively designated 12A, 12B, 12C... 12N, are each of the type described in the prior specification to patent application ZA2010/01315 and are each partially inserted in a respective rock hole, respectively designated 14A, 14B, 14C...14N, which are drilled, in a hanging wall 16 of a mine working excavation, preferably at equidistant intervals.

[0022] The specific details of these rock movement sensors 12 are covered in the prior specification. However, for ease of explanation and with reference to sensor 12A, each rock movement sensor includes a rod 18 which is secured by an anchor 20 at the blind end 22 of the rock hole 14, the rod co-axially extending to protrude from the hanging wall 16. This protruding end is enclosed by an indicator housing 24.

[0023]The indicator housing 24 of each sensor 12 is axially movable relative to the rod 18, the rod being fixed relative to the respective rock hole 14.

[0024] Each sensor housing 24 contains a printed circuit board (PCB) 26. This PCB, as will be more fully described below, receives input when movement of the rock face 16 is detected, which causes electrical current to be diverted from a green LED 28A to a red LED 28B as visual indication that movement of the hanging wall has occurred in the vicinity of that particular rock movement indicator 12.

[0025] The system and method of the invention are not limited by the precise workings of the rock movement sensor as described herein, and it is anticipated within the scope of the invention that the sensor can be of any suitable configuration and design. For example, the invention is equally applicable to a rock movement sensor of the type that has an elongate body which extends between opposed hanging and foot walls of the mine and which detects closure between these two walls by axial compression of the body by the closure. [0026] A central control unit 30 can be positioned at any locality in the vicinity of the mine working excavation. The locality is, preferably, a safe and stable locality. The unit 30, in this particular embodiment, includes a power supply 32, a control PCB 34 and a green and red LED, respectively designated 36A and 36B. The power supply energises a power line 38 which is linked to each of the individual rock movement sensors 12, thereby providing power to the sensors. Alternatively each sensor can have an individual self-contained power supply.

[0027]As illustrated by Figure 2, a signal line 42 links the control PCB 34 to each sensor PCB 26. A switch 44 within the PCB 26 will reroute current, in response to detected rock face movement, from the green LED 28A to the red LED 28B. A voltage pulse will, as a consequence, be generated and transmitted along the signal line 42 to the control PCB 34, as a signal that movement has occurred.

[0028] It is anticipated, as will be described below, that each individual sensor excludes warning means (i.e. the LED's) and that this function is provided solely by the central control unit 30.

[0029] Each rock movement sensor 12 is protected by a casing 47, and the power line 38 and the signal line 42 enter and leave the casing 47 at respective input and output terminals respectively designated 48 and 50, located on opposed ends of the casing. [0030] Each of the rock movement sensors 12 may be linked to one another via the power line 38 and signal line 42, either in series or parallel (the invention is not limited in this regard) depending on which is appropriate for the system's integration into a specific environment. [0031] With specific reference to rock movement sensor 12A, should this sensor detect movement, within its vicinity of the rock face 16, this movement will cause the first housing 24 of the indicator to axially move relative to the rod 18 causing, in this particular example, mechanical actuation of the switch 44 of the PCB 26 to divert electric current, supplied by the power line 38, from the green LED 28A to the red

LED 28B, causing the red LED to emit red light.

[0032] The switch 44 within the PCB 26, also, can be electrically actuable.

[0033]The red LED 28B power circuit is connected in parallel with the signal bridge 46. When the diversion of current occurs, and the red LED is energized, a potential difference occurs across a signal bridge 46, as communication of this occurrence.

An electrical signal or current is prevented from flowing back to the red LED power circuit by a diode 52 on the signal bridge.

[0034] On receipt of the voltage pulse signal along the signal line 42, the red LED 36B is energized. In the absence of a signal along the signal line 42, a green LED 36A remains energized, providing a visual indication that none of the rock movement indicators 12 along the length of the particular excavation has detected movement of the hanging wall within its vicinity.

[0035] Each set of LEDs 28 and 36 are housed in a protective, transparent shield 56 on the respective external faces of the rock movement sensor casing 47 and primary indication unit 30.

[0036] In a second embodiment of the invention, as illustrated in Figure 3, each sensor 60, in this particular example, differs from the sensors 12 of the earlier embodiment in that they are not pre-configured only to generate a signal pulse in response to rock movement of a particular, pre-defined magnitude, but to generate a signal to any rock movement and that signal pulse being proportional, in at least one parameter, to the magnitude of the rock movement. Also, the sensors 60 do not have indicator or warning capacity, that function being provided by the control unit 30.

[0037]The power line 38, in this example, has a twofold function: providing power to the sensors 60 from the power supply 32 and as a conductive serial communication link between each sensor and the control unit 34. However, the invention is not limited in this respect and the communication link can be wireless or fibre-optic.

[0038] Signals, generated by one or more of the serially connected sensors 60, travel along the power line 38 to a receiver 64. A filter 66 is interposed on the power line 38, between a receiver 64 and the plurality of sensors, to filter the signals of electrical noise.

[0039]A micro-controller or processor 62 receives information input from the receiver, based on the quantitative aspect of the signals received.

[0040] The processor, pre-programmed with a logic algorithm, is capable of processing this input and, if the signal exceeds a particular pre-determined level, causing a warning or alarm device 68 to generate an alarm response. The alarm response can be audible or, like with the earlier embodiment, a visual response through the illuminations of an LED or the like.

[0041] Each sensor can also generate a signal that is unique to the particular transmitting sensor. This will enable identification of the precise locality of the movement or, cumulatively generation of, a profile of rock movement. [0042] The central control unit can include a visual output monitor 70, connected to the processor 62, to provide a visual display of the profile of rock movement. Also, the response by the sensors to polling signals, initiated by the processor and addressed to each sensor 60, can also be visually displayed on the monitor to enable an operator to determine which sensors are in working order and which are not and therefore require attendance.

Claims

1. The invention provides a system for monitoring movement of a rock face which includes:

- a receiver for receiving signals generated by the sensors;

- an warning device which is actuable to generate an alarm response to at least one signal received by the receiver.

2. A system according to claim 1 wherein each sensor generates a signal based on the identity of the sensor or the magnitude of movement of the rock face, or both.

3. A system according to any one of claims 1 or 2 wherein each sensor is engaged with the rock face.

4. A system according to any one of claims 1 to 3 which includes a logic device which receives input from the receiver based on signals received by the receiver and generates an output response.

5. A system according to claim 4 wherein the output response is the actuation of the warning device to generate the alarm response when the magnitude of rock face movement, at one or more locations, exceeds a predetermined level.

6. A system according to claim 4 or 5 wherein the logic device is programmable to identify and communicate the origin of each signal.

7. A system according to any one of claims 4 to 6 wherein the logic device is programmable to initiate periodic polling signals addressed to one or more of the sensors and to identify and communicate the origin of a response to these polling signals.

8. A system according to any one of claims 1 to 7 wherein the communication link is a serial communication link or a parallel communication link.

9. A system according to any one of claims 1 to 8 wherein the communication link is established over a conductive, a fibre-optic or a wireless link.

10. A system according to claim 9 wherein the sensors are individually powered or powered from a remote power source via a power line.

11. A system according to claim 10 wherein the conductive communication link is the power line.

12. A method for detecting movement of a rock face of an excavation which includes the steps of:

(d) linking each sensor to the control unit, by means of a communication link, to provide communication between each sensor and the control unit;

(e) sending a signal, generated by a sensor in response to movement of the rock face, along the communication link to the control unit; and

(f) generating an alarm response on receipt of the signal by the control unit.

13. A method according to claim 12 wherein the sensors are linked to the control unit in series or in parallel.

14. A method according to claim 12 or 13 wherein the sensors and the control unit are physically lined or wirelessly linked.