WO2021240063A1 - Method, system and computer program product for real-time monitoring of stress changes in an excavation - Google Patents
Method, system and computer program product for real-time monitoring of stress changes in an excavation Download PDFInfo
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- WO2021240063A1 WO2021240063A1 PCT/FI2021/050377 FI2021050377W WO2021240063A1 WO 2021240063 A1 WO2021240063 A1 WO 2021240063A1 FI 2021050377 W FI2021050377 W FI 2021050377W WO 2021240063 A1 WO2021240063 A1 WO 2021240063A1
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- WIPO (PCT)
- Prior art keywords
- strain
- excavation
- stress
- measurement devices
- directions
- Prior art date
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- 238000009412 basement excavation Methods 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title claims abstract description 54
- 238000012544 monitoring process Methods 0.000 title claims abstract description 16
- 238000004590 computer program Methods 0.000 title claims description 10
- 238000005259 measurement Methods 0.000 claims abstract description 59
- 238000012545 processing Methods 0.000 claims abstract description 24
- 238000011068 loading method Methods 0.000 claims description 23
- 239000000306 component Substances 0.000 claims description 22
- 238000012417 linear regression Methods 0.000 claims description 14
- 230000001419 dependent effect Effects 0.000 claims description 4
- ADIMAYPTOBDMTL-UHFFFAOYSA-N oxazepam Chemical compound C12=CC(Cl)=CC=C2NC(=O)C(O)N=C1C1=CC=CC=C1 ADIMAYPTOBDMTL-UHFFFAOYSA-N 0.000 abstract 1
- 239000011435 rock Substances 0.000 description 13
- 239000000243 solution Substances 0.000 description 7
- 238000004364 calculation method Methods 0.000 description 6
- 238000006073 displacement reaction Methods 0.000 description 6
- 230000015654 memory Effects 0.000 description 6
- 238000004891 communication Methods 0.000 description 4
- 230000006854 communication Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000011065 in-situ storage Methods 0.000 description 4
- 238000005065 mining Methods 0.000 description 4
- 230000002787 reinforcement Effects 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 238000011439 discrete element method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000012163 sequencing technique Methods 0.000 description 2
- 230000003313 weakening effect Effects 0.000 description 2
- 208000010392 Bone Fractures Diseases 0.000 description 1
- 206010017076 Fracture Diseases 0.000 description 1
- 238000007476 Maximum Likelihood Methods 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000012804 iterative process Methods 0.000 description 1
- 235000020061 kirsch Nutrition 0.000 description 1
- 238000013488 ordinary least square regression Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- ACWBQPMHZXGDFX-QFIPXVFZSA-N valsartan Chemical class C1=CC(CN(C(=O)CCCC)[C@@H](C(C)C)C(O)=O)=CC=C1C1=CC=CC=C1C1=NN=NN1 ACWBQPMHZXGDFX-QFIPXVFZSA-N 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/26—Indicating devices
- E02F9/264—Sensors and their calibration for indicating the position of the work tool
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- E21B49/006—Measuring wall stresses in the borehole
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
- E21F17/18—Special adaptations of signalling or alarm devices
- E21F17/185—Rock-pressure control devices with or without alarm devices; Alarm devices in case of roof subsidence
Definitions
- the present invention relates in general monitoring of excavations. In particular, however not exclusively, the present invention concerns monitoring stress changes in excavations.
- a rock body is subjected to stress in almost any point.
- the in situ stress depends mostly on kind of loading which the rock mass is subjected to and has been subjected to in prior.
- the most important loads are tectonic processes and load ing by weight of overlying strata.
- stress may be char acterized by a stress tensor. It may be defined in a point of space as a matrix of nine perpendicular stress components.
- a method for real-time monitoring of stress changes in an excavation such as in a mine or a tunnel.
- the method com prises determining strain data of the excavation by at least three strain meas urement devices, such as borehole extensometers, wherein the strain measure ment devices are arranged surrounding the excavation to determine the strain data along different directions with respect to each other, receiving the deter mined strain data on a processing unit arranged in connection with the strain measurement devices, and back-calculating, or inverse calculating, by the pro cessing unit, a stress change based on the received strain data.
- Back-calculation herein refers to a process in which input parameters are ad justed until the calculated result coincides with the actual result found, that is, with the determined strain data and/or a stress change related determined there from.
- strain data may be deter mined in at least three different directions, however, any two of the directions not in opposite directions (having angle of 180 degrees therebetween).
- strain data may be determined in at least six different directions, however, any two of the directions not in opposite directions (having angle of 180 degrees therebetween).
- the method may comprise determining a displacement and/or an angular displacement in a direction, or a plurality of displacements in various directions, and calculating a strain change based on the determined displace ments).
- the calculated strain(s) may then be utilized to produce the strain data.
- the stress state or the change of stress state may then be deter mined, such as calculated, based on the strain data.
- the strain measurement devices may be arranged such that the di rections, or imaginary lines extending along the directions, intersect inside the excavation. Flowever, the directions are such that they do not align, such as two directions having 180 degrees with respect to each other.
- the back-calculating may include the use of superpo sition to calculate the strain change based on strain components included the determined strain data.
- the stress change may be determined based on pre-determined unit loads with respect to said different directions and, optionally, corresponding pre-determined loading factors.
- the method may comprise, preferably prior to the deter mination of the strain data, determining unit loads.
- the unit loads may be deter mined with respect to each of the directions related to the strain measurement devices.
- the unit loads are stored in the computing device, such as inside the excavation or outside thereof.
- the stored unit loads may be utilized in the back-calculation to deter mine the stress change.
- the back-calculating may, alternatively or in addition, comprise utilizing multiple linear regression, wherein a dependent variable of the multiple linear regression is the determined strain and explanatory variables of the multiple linear regression are the stress tensor components or loading fac tors.
- the directions of two of the devices are different by an angle in the range of 10 to 45 degrees, optionally, by an angle of 15 or 20 de grees.
- the directions are arranged in 45 degrees with respect to each other.
- the determining may comprise determining strain data of the excavation by at least six strain measurement devices.
- the at least six strain measurement devices may form two sets of three measurement de vices arranged in opposite directions with respect to a longitudinal direction of the excavation.
- the method may comprise determining the initial stress level based on a plurality of stress levels determined during the excavation work.
- the strain measurement devices may be strain gauges, extensometers, such as borehole extensometers, linear variable differential transformers (LVDTs), rebar rock bolts instrumented with strain gauges, incli nometers, or an array of convergence measurement points.
- extensometers such as borehole extensometers, linear variable differential transformers (LVDTs), rebar rock bolts instrumented with strain gauges, incli nometers, or an array of convergence measurement points.
- the borehole extensometers may be at least 10 or 20 meters in length.
- the system may be configured to provide an alert if a stress threshold is exceeded.
- the alert may be issued as a visible and/or audible alert, and/or by a signal transmitted from the processing unit to an external sys tem.
- a computer program product for real-time monitoring of stress changes in an excavation.
- the computer program product comprises program instructions which when executed by a processing unit cause the processing unit to perform the method in accordance with the first aspect.
- the present invention provides a method, a computer program product and a system for remote monitoring of an electronic treatment device for treating a patient, such as a negative pressure treatment device.
- the present invention provides advantages over known solutions in that online and real time access to in situ stress state can be used to optimize the mining sequence, to reduce ore dilution and to limit ore losses. It can also support more precise reinforcement design and give the ability to detect and to react to unexpected changes while maintaining a higher level of safety and avoiding collapses. Stress state change monitoring is able to give feedback about the success of mining sequencing and sufficiency of ground control methods. With the real-time monitoring of the stress state, it is possible to increase the safety of underground mines especially if the stress changes cause significant risks.
- first”, “second”, etc. are herein used to distinguish one element from other element, and not to specially prioritize or order them, if not otherwise ex- pi icitly stated.
- Figure 1 illustrates schematically an excavation according to an embodiment of the present invention.
- Figure 2 illustrates schematically a system according to an embodiment of the present invention.
- FIGS 3A and 3B illustrate schematically a system according to an embodi- ment of the present invention.
- Figure 4 shows a flow diagram of a method in accordance with an embodiment of the present invention.
- Figure 5 shows a flow diagram of a method in accordance with an embodiment of the present invention.
- DETAILED DESCRIPTION OF SOME EMBODIMENTS Figure 1 illustrates schematically an excavation 100 according to an embodi ment of the present invention.
- the dashed lines perpendicular with respect to the longitudinal direction 5 of the excavation 100 illustrate the progress of the excavation activities, such as mining, in the excavation 100.
- At 30 is shown a stress state or level of the excavation 100 in accordance with the progress.
- the initial stress state or level 31 is shown as a horizontal dashed line.
- the in situ stress depends mostly on kind of loading which the rock mass is subjected to and has been subjected to.
- the most important loads are tectonic processes and loading by weight of overlying strata.
- Figure 2 illustrates schematically a system according to an embodiment of the present invention.
- the system comprises at least three strain measurement de vices 15A-15C, or a set 15 of at least three of such devices 15A-15C, for the two-dimensional case or at least six for the three-dimensional case, arranged into the excavation 100, preferably into the surroundings 20 of the excavation 100.
- the strain measurement devices 15A-15C may be arranged to determine the strain data along different directions with respect to each other such as shown in Fig. 2.
- the first strain measurement device 15A has an angle of 60 degrees relative to the horizontal
- the second strain measurement device 15B has an angle of 45 degrees relative to the horizontal
- the third strain measurement device 15C has an angle of 15 degrees rela tive to the horizontal.
- the system may comprise a processing unit 50, such as a computer or computing device, arranged to receive the determined strain data and to back-calculate a stress change based on the received strain data.
- the processing unit 50 is preferably at least in communication con nection with the strain measurement devices 15A-15C.
- the strain measurement devices 15, 15A-15C may be strain gauges, extensometers, such as borehole extensometers, linear variable differential transformers (LVDTs), rebar rock bolts instrumented with strain gauges, inclinometers, or an array of convergence measurement points.
- extensometers such as borehole extensometers, linear variable differential transformers (LVDTs), rebar rock bolts instrumented with strain gauges, inclinometers, or an array of convergence measurement points.
- the strain measurement devices 15A-15C may be multi point borehole extensometers to measure strain in multiple locations.
- the extensometers may be, for example, 20 meters long and installed to angles of 20, 50, and 70 degrees measured from horizontal.
- the extensometers may in clude six anchor points placed in every 3.33 meters. Such devices may give five displacement or strain values, one between each two anchor points.
- the strain measurement devices 15A-15C are bore hole extensometers.
- the borehole extensometers may be at least 10 or 20 me ters in length.
- the borehole extensometers may be such as they are anchored in a plurality of positions of the extensometers, and, optionally, arranged to measure strain at the plurality of positions thereof.
- the directions of two of the devices may be different by an angle in the range of 10 to 45 degrees, optionally, by an angle of 15 or 20 degrees.
- the strain measurement devices 15A- 15C of a set 15 may be arranged such that the directions thereof intersect inside the excavation 100.
- This thus preferably refers to imaginary lines extending from the devices 15A-15C along their directions and thereby the imaginary lines, in fact, may be arranged to intersect in the excavation 100 as shown in Fig. 2 by dashed lines.
- the system may comprise at least six strain measure ment devices. Increasing the number of strain measurement devices reduces the effect of noise of the measurements.
- the strain measurement devices 15; 15A-15C may, preferably, be arranged at least 10 to 100 centimeters away from the wall of the excavation 100 in order to avoid the damage of excavation work, such as damage due to blasts, on the measurements, such as related to excavation damaged zone close to the wall.
- strain measurement devices 15; 15A-15C may, preferably, be arranged close to the excavation 100, such as not farther than two to five times the size, such as width, of the excavation 100, in order to be able to measure the changes in the stress state.
- the strain measurement devices 15; 15A-15C may be arranged not to intersect or pass through rock joints or weak zones in the surrounding rock mass so as to avoid movements therein affecting the devices 15; 15A-15C.
- FIGs 3A and 3B illustrate schematically a system according to an embodi ment of the present invention.
- the system is similar to one shown in Fig. 2, however, it comprises at least six strain measurement devices arranged into two sets 15 and 25 of such devices 15A-15C.
- the at least six strain measurement devices forming the two sets 15, 25 of at least three measurement devices may be arranged in opposite directions with respect to a longitudinal direction 5 of the excavation 100.
- This is illustrated in Fig. 3A in which the sets 15, 25 are in an angle 16, 26 with respect to a perpendicular direction 6 relative to the longitudinal direction 5.
- the angle differs from 0 and 180 degrees and is preferably in the range of 10-75 degrees, more preferably in the range of 15-60 degrees, and most preferably 45 degrees. This allows determining the stress changes in three dimensions.
- Figure 3B further illustrates how to sets 15, 25 may be arranged into the sur roundings 20 of the excavation 100.
- the system may be configured, such as by the pro cessing unit 50, to provide an alert if a stress threshold is exceeded.
- the thresh old may be linked to the stress state or level is illustrated at 30 in Fig. 1 .
- Figure 4 shows a flow diagram of a method in accordance with an embodiment of the present invention.
- Step 400 refers to a start-up phase of the method. Suitable equipment and com ponents and measurement devices are obtained, and systems assembled and configured for operation.
- Step 410 refers to determining strain data of the excavation 100 by at least three strain measurement devices 15; 15A-15C, wherein the strain measurement de vices 15; 15A-15C are arranged surrounding the excavation 100 to determine the strain data along different directions with respect to each other.
- Step 420 refers to receiving the determined strain data on a processing unit 50 arranged in connection with the strain measurement devices 15; 15A-15C.
- Step 430 refers to back-calculating, by the processing unit 50, a stress change based on the received strain data.
- the back-calculating may include the use of superpo sition to calculate the strain change based on strain components included the determined strain data.
- the strain components may be determined based on unit loads and corresponding loading factors.
- the back-calculating may comprise utilizing multiple linear regression, wherein a dependent variable of the multiple linear regression is the determined strain and explanatory variables of the multiple linear regres sion are the stress tensor components or loading factors.
- variables to be solved are at least two principal stresses (e.g. oi and 02) and a first direction (e.g. a), such as related to an angle of or between the two principal stresses.
- variables to be solved may be three principal stresses (e.g. oi , 02 and 03) and a first and a second direction (e.g. a and b), and, prefer ably, in a third direction y, such as related to angles of or between the principal stresses.
- the angles may refer to pitch, yaw and roll, respectively.
- the two other stresses or stress components may be assumed to lie in a horizontal plane.
- the method may further comprise determining the initial stress state or level 31 based on a plurality of stress states or levels 32 deter mined during the excavation work as shown in Fig. 1 .
- the determination of the initial stress state or level 31 may be based on back-calculating from the one of the of plurality of stress states or levels 32 by taking into account the stress changes determined during the excavation work.
- Method execution is stopped at step 499.
- the method may be performed or executed continuously, intermittently, repeatedly, or on demand.
- the processing unit 50 may be arranged to poll the measurement devices 15;
- Figure 5 shows a flow diagram of a method in accordance with an embodiment of the present invention.
- the method may comprise, preferably prior to the determination 410 of the strain data, determining 402 unit loads or stresses.
- the unit loads or stresses may be determined with respect to each of the directions related to the strain measurement devices.
- the unit loads or stresses are stored, at 404, in the computing device 50, such as inside the excavation 100 or outside thereof.
- the stored unit loads or stresses may then be utilized in the back- calculation to determine the stress change. While, the determination of the stress change may be performed substantially continuously or in certain inter vals, such as once in couple of hours or so, the determination of the unit loads or stresses may be performed only once or periodically, such as during consec utive phases of the excavation work.
- numerical modelling methods may be used in the back- calculations for determining the strains around the excavation 100.
- continuum methods are methods like Finite Element Method (FEM), Finite Difference Method (FDM) and Boundary Element Method (BEM).
- discontinuum methods are Dis crete Element Method (DEM) with codes as UDEC and 3DEC and Discrete Frac ture Network (DFN).
- the stress changes may be determined in two or three dimensions, for example, depending on the number and configuration, such as orientations, of the strain measurement devices 15, 25; 15A-15C.
- the stress state change may be back-calculated using linear regression of strain change observations, the elastic constitutive relation and the superposition principle.
- an assumption of continuous, homogene ous, isotropic and linearly elastic rock (CH ILE) conditions may be done.
- the loading stress tensor acting on a rock body of the excavation 100 may be divided to its components and sum up the results of strains or displacements.
- the total strain of selected sections within the medium may be calculated by simple summing up the components.
- the strain may be expressed as strain from unit load multiplied by a load factor.
- a dependent variable of the mul tiple linear regression may be the determined strain and the explanatory varia bles of the multiple linear regression may be the stress tensor components or loading factors.
- Least square estimation and related methods which include Ordinary least square, General ized least square, Percentage least square, Iteratively reweighed last squares, Instrumental variables, Optimal instruments and Total least squares.
- Maximum likelihood estimation methods which includes also Least absolute deviation, Ridge regression and Adaptive estimation method.
- the processing unit 50 may comprise an input for external units which may be connected to a communication interface of the unit 50.
- External unit may comprise wireless connection or a connection by a wired manner.
- the communication interface provides interface for communi cation with external units such as the strain measurement device 15, 25; 15A- 15C and/or external systems for outputting the alert, if any.
- There may also be connecting to the external system, such as a laptop or a handheld device.
- the processing unit 50 may comprise one or more processors, one or more memories being volatile or non-volatile for storing portions of computer program code and any data values and possibly one or more user interface units.
- the mentioned elements may be communicatively coupled to each other with e.g. an internal bus.
- the processor is at least configured to implement at least some method steps as described.
- the implementation of the method may be achieved by arranging the processor to execute at least some portion of computer program code stored in the memory causing the processor, and thus the processing unit 50 and/or the system, to implement one or more method steps as described.
- the proces sor is thus arranged to access the memory and retrieve and store any infor mation therefrom and thereto.
- the processor herein refers to any unit suitable for processing information and control the operation of the pro cessing unit, among other tasks.
- the operations may also be implemented with a microcontroller solution with embedded software.
- the memory is not limited to a certain type of memory only, but any memory type suitable for storing the described pieces of information may be applied in the context of the present invention.
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Abstract
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Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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EP21729910.6A EP4158158A1 (en) | 2020-05-26 | 2021-05-26 | Method, system and computer program product for real-time monitoring of stress changes in an excavation |
CA3180412A CA3180412A1 (en) | 2020-05-26 | 2021-05-26 | Method, system and computer program product for real-time monitoring of stress changes in an excavation |
AU2021279301A AU2021279301A1 (en) | 2020-05-26 | 2021-05-26 | Method, system and computer program product for real-time monitoring of stress changes in an excavation |
Applications Claiming Priority (2)
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FI20205536A FI20205536A1 (en) | 2020-05-26 | 2020-05-26 | Method, system and computer program product for real-time monitoring of stress changes in an excavation |
FI20205536 | 2020-05-26 |
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WO2021240063A1 true WO2021240063A1 (en) | 2021-12-02 |
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PCT/FI2021/050377 WO2021240063A1 (en) | 2020-05-26 | 2021-05-26 | Method, system and computer program product for real-time monitoring of stress changes in an excavation |
Country Status (5)
Country | Link |
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EP (1) | EP4158158A1 (en) |
AU (1) | AU2021279301A1 (en) |
CA (1) | CA3180412A1 (en) |
FI (1) | FI20205536A1 (en) |
WO (1) | WO2021240063A1 (en) |
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CN117167087B (en) * | 2023-08-30 | 2024-07-02 | 中铁四局集团有限公司 | Rock burst prevention and control early warning system and method based on stress change of fault-penetrating anchor cable |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20170091355A1 (en) * | 2015-09-28 | 2017-03-30 | Freeport-Mcmoran Inc. | Ground support design tool |
CN107842394A (en) * | 2017-10-23 | 2018-03-27 | 青岛理工大学 | Dynamic elastic modulus detection method for stability of mining top plate of large-span underground chamber |
-
2020
- 2020-05-26 FI FI20205536A patent/FI20205536A1/en unknown
-
2021
- 2021-05-26 WO PCT/FI2021/050377 patent/WO2021240063A1/en unknown
- 2021-05-26 EP EP21729910.6A patent/EP4158158A1/en active Pending
- 2021-05-26 CA CA3180412A patent/CA3180412A1/en active Pending
- 2021-05-26 AU AU2021279301A patent/AU2021279301A1/en active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20170091355A1 (en) * | 2015-09-28 | 2017-03-30 | Freeport-Mcmoran Inc. | Ground support design tool |
CN107842394A (en) * | 2017-10-23 | 2018-03-27 | 青岛理工大学 | Dynamic elastic modulus detection method for stability of mining top plate of large-span underground chamber |
Non-Patent Citations (1)
Title |
---|
MARTIN C D ET AL: "Stress, instability and design of underground excavations", INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, PERGAMON, UNITED KINGDOM, vol. 40, no. 7, 2 September 2003 (2003-09-02), pages 1027 - 1047, XP085040125, ISSN: 1365-1609, DOI: 10.1016/S1365-1609(03)00110-2 * |
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CA3180412A1 (en) | 2021-12-02 |
AU2021279301A1 (en) | 2023-02-02 |
EP4158158A1 (en) | 2023-04-05 |
FI20205536A1 (en) | 2021-11-27 |
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