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US20120230776A1 - Slope of an Open Cut Mine - Google Patents

Slope of an Open Cut Mine Download PDF

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Publication number
US20120230776A1
US20120230776A1 US13/505,647 US201013505647A US2012230776A1 US 20120230776 A1 US20120230776 A1 US 20120230776A1 US 201013505647 A US201013505647 A US 201013505647A US 2012230776 A1 US2012230776 A1 US 2012230776A1
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US
United States
Prior art keywords
borehole
reinforcing member
batter
crest
face
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US13/505,647
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English (en)
Inventor
Andrew Haile
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BHP SSM Indonesia Holdings Pty Ltd
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2009905382A external-priority patent/AU2009905382A0/en
Application filed by Individual filed Critical Individual
Assigned to BHP BILLITON SSM DEVELOPMENT PTY LTD. reassignment BHP BILLITON SSM DEVELOPMENT PTY LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HAILE, ANDREW
Publication of US20120230776A1 publication Critical patent/US20120230776A1/en
Abandoned legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00—Excavations; Bordering of excavations; Making embankments
    • E02D17/18—Making embankments, e.g. dikes, dams
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00—Excavations; Bordering of excavations; Making embankments
    • E02D17/20—Securing of slopes or inclines
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21C—MINING OR QUARRYING
    • E21C41/00—Methods of underground or surface mining; Layouts therefor
    • E21C41/26—Methods of surface mining; Layouts therefor

Definitions

  • This invention relates to an improved slope of an open cut mine and a method of forming a reinforced rock slope in an open cut mine.
  • the invention has been developed for an application in an open cut mine and it will be convenient to hereinafter describe the invention with reference to this particular application. It should be appreciated that the invention may have other applications in an open excavation environment, such as a quarry, and the invention is not to be limited to use only in a mine.
  • Mining companies use various methods of extracting ore from the ground, and an open cut mine is one method that requires the removal of a substantial volume of material.
  • the excavation of the material develops a pit with a floor and a slope extending up from the floor.
  • the slope is formed by a series of batters, with berms spacing the batters and providing rockfall catchment or a ramp for mining traffic accessing the pit floor. It is generally desirable to maximise the angle of the slope as it has the potential to minimise the extraction of waste material and maximise the extraction of ore.
  • a batter is generally excavated to an angle that, having regard to the characteristics of the rock, is naturally stable. This is generally no greater than 70° and normally more in the range of 50° to 70°. Where the berm at the top of the batter is acting as a ramp, or accommodating other critical mine infrastructure such as vent stacks or pumping stations, it is desirable to decrease the angle to account for the additional load and risk.
  • any angle other than 90° will typically result in inefficiencies.
  • a batter of less than 90° will result in ore being left behind to maintain the berm above.
  • a batter of less than 90° may result in waste material being unnecessarily removed, particularly when it is outside the area of the ore deposit.
  • open cut mines still tend to have batter faces at angles less than 70° to ensure natural stability.
  • a safety issue with open cut mines relates to rocks falling from the face of the batter onto traffic or personal on the berm below. This is exacerbated where the batter is of less than 90° as the rocks bounce off the batter face and project out from the toe of the batter onto the berm, or past the berm and into lower working areas of the mine. It has been found that with a batter angle of about 60°, the rocks fall generally between 2 m and 9 m from the toe of the batter but may well exceed this. This is a wide spread particularly given a berm may be generally around 10 m.
  • an improved slope of an open cut mine including a plurality batters with a berm extending from a toe of each batter, each batter having an excavated batter face which is substantially vertical and extends from the toe to a crest of the batter, reinforcing means installed prior to the excavation of the face and spaced from the proposed crest, the reinforcing means including a plurality of reinforcing members each located in a substantially vertical borehole formed at said spacing from the proposed crest, each borehole extends to a depth of at least the distance between the crest and the toe, each reinforcing member extends substantially the depth of the each borehole
  • each borehole exceeds the distance between the crest and the toe by up to 15%. It is further preferred that each borehole is spaced from an adjacent borehole by between 1000 mm and 5000 mm. It is still further preferred that each reinforcing member is a bar or cable of a diameter of between 20 mm and 100 mm. It is preferred that the bar or cable is formed from steel, or alternatively each reinforcing member is formed from fibreglass. It is preferred that the reinforcing member is grouted in position in the borehole. It is preferred that the length of the reinforcing member exceeds the depth of the borehole, and in particular the reinforcing member extends out from the borehole to interact with a safety fence extending between the plurality of boreholes.
  • the length of the reinforcing member is less than the length of the borehole so that the reinforcing member is countersunk in the borehole. It is preferred that the substantially vertical face is within the range of 75° to 90°. It is further preferred that each borehole is spaced from the crest by no less than 800 mm.
  • a method of forming a reinforced rock slope in an open cut mine including drilling a plurality of vertical boreholes to a borehole depth, locating a reinforcing member in each borehole which is substantially the length of the borehole depth, grouting the reinforcing bar in the hole, locating a crest of a batter which is spaced from the boreholes, excavating a face to the batter which is substantially parallel with the boreholes, the height of the batter face from the crest to a toe is no less than the depth of the borehole adjacent the face, wherein the excavation of the face is performed after the reinforcing member has been grouted in place in the borehole.
  • each borehole it is no greater than 300 mm in diameter. It is further preferred to space the crest of the batter from each borehole so that the reinforcing member is behind the crest of the batter by no less than 800 mm. It is still further preferred to space each borehole from its adjacent borehole at no less than 1000 mm centres. It is still further preferred to provide a reinforcing member in the form of a reinforcing bar is no less than 40 mm in diameter. It is still further preferred to drill the borehole depth to exceed the height of the face of the batter by at least 15%. It is still further preferred to provide a length of the reinforcing member that is less than the length of the borehole so that the reinforcing member is countersunk in the borehole. It is still further preferred that the method of excavating the face includes drilling and blasting to produce the substantially vertical face within a range of 75° to 90°.
  • FIG. 1 is a side cross-sectional view of a schematic illustration of an improved slope according to the invention.
  • FIG. 2 illustrates a schematic view of an unimproved slope prior to excavation of the batters.
  • FIG. 3 illustrates an improved slope with the batter excavated.
  • FIG. 1 that illustrates a natural surface level 1 having been excavated to produce an improved slope 2 of an open cut pit.
  • the improved slope 2 includes a plurality of horizontal berms 3 , each spaced by a vertical batter 4 .
  • Each batter has a face 5 which extends from a toe 6 of the batter to a crest 7 .
  • the slope extends from the natural surface level 1 to the floor 8 of the pit.
  • FIG. 2 illustrates a portion of the open cut mine prior to excavation.
  • a crest 7 of the proposed batter 4 is selected, and a series of boreholes 9 spaced from that crest 7 are drilled to a borehole depth.
  • This spacing is preferably no less than 800 mm, however this spacing x is merely preferred. Spacings x of other distances are clearly possible, however it is generally desirable that the spacing x be selected to be sufficient so as to reduce the likelihood that the borehole 9 will be exposed when the batter is excavated.
  • the face 5 of the batter is exposed by a technique of drill and blasting which can cause the crest 7 to crumble. Accordingly it is preferable that the borehole 9 be spaced from the crest by 1500 mm to avoid the hole being exposed when blasting.
  • each borehole 9 have a diameter of no greater than 300 mm, however this dimension is merely preferred.
  • the function of the borehole 9 is to accommodate a reinforcing member 10 and therefore the diameter of the borehole 9 is dictated to some extent by the characteristics of the reinforcing member 10 .
  • the reinforcing member 10 be grouted in position in the borehole 9 , and therefore the diameter of the borehole will need to be selected to satisfy minimum cover requirements, particularly where the reinforcing member 10 is a steel bar. Accordingly, it is to be appreciated that the diameter of the borehole 9 may vary, however it is generally preferred that the diameter be less than 300 mm.
  • Each borehole 9 is preferably drilled behind the crest at a spacing y to space it from an adjacent borehole preferably by no less than 2000 mm, where the berm is not supporting critical mine infrastructure. Where the berm is acting as a ramp, or supporting critical mine infrastructure such as pumping stations or ventilation shafts, the spacing of the boreholes may need to be less than 2000 mm. It is more likely that each borehole be spaced y from an adjacent borehole by between 2,000 and 5,000 mm. This spacing y will specifically be dependent on the characteristics of the rock structure being reinforced by the reinforcing member 10 and the desired level of reliability in the slope stability.
  • the rock structure comprises many closely spaced planes of weakness such as a fault, joints or fracture, it may be appropriate to have the spacings y of each adjacent borehole relatively close. In contrast, if the rock structure comprises very few planes of weakness it may be appropriate to have the spacings y relatively further apart. In either case, the spacings y can be set having regard to information revealed in a geological survey and variable between adjacent boreholes 9 .
  • the reinforcing member 10 located in each borehole 9 may take any appropriate form.
  • the preferred form of reinforcing member is a bar or cable formed from steel, however as an alternative it may be formed as a fibreglass rod.
  • the reinforcing member 10 is a bar of steel, it is preferred that the diameter of the bar be between 20 mm and 100 mm. The diameter of the bar will be selected according to the characteristics of the rock, depth of borehole and/or the desired level of reliability in slope stability. The bar is placed in situ and grouted in position.
  • each reinforcing member 10 does not exceed the depth of the borehole 9 . It is generally desirable that the reinforcing member 10 and grout are countersunk so as to reduce the likelihood that the top of the reinforcing member 10 is exposed. The top of the reinforcing member 10 might be exposed if the crest 7 crumbles, say as a result of blasting the batter face 5 . Accordingly countersinking to a depth of 1000 mm or greater is desirable. It may however be appropriate in certain applications that the reinforcing member 10 does exceed the depth of the borehole 9 as this enables the reinforcing member 10 to project from the borehole 9 .
  • the projecting reinforcing member 10 may be used for any suitable purpose, however it is preferred that it interacts with a safety fence 11 extending between the plurality of adjacent boreholes 9 . This alternate embodiment is illustrated in FIGS. 2 and 3 .
  • the material 12 beyond the crest 7 that is to be excavated can be excavated by any suitable means.
  • the preferred means illustrated in FIG. 2 involves drilling a plurality of additional boreholes 13 at the crest 7 of the batter 4 , and beyond the crest 7 . Charges can then be placed in the boreholes 13 and the material be moved using drill and blast techniques understood and known by those people operating in this industry.
  • FIG. 3 illustrates the improved slope with the exposed batter face 5 extending at 90° to the berm 3 below.
  • the batter face 5 according to this invention is substantially vertical, and it is generally preferred that the substantially vertical face 5 be within the range of 75°-90°.
  • the boreholes 9 including the reinforcing member 10 according to the invention extends to a depth at least equal to a distance between the crest 7 and toe 6 of the batter face 5 . It can be seen from FIG. 3 that it is preferred that the borehole depth extend beyond the toe, and it is particularly preferred that it extend beyond the toe by up to 15%. It has been found that by extending the reinforced borehole 9 by this distance reduces the likelihood of shear failure of the batter at the toe of the batter.
  • an improved slope 2 as hereinbefore described reduces the inefficiencies associated with a slope having a batter angle of less than 70°. Furthermore, it will reduce the distance from the toe within which rock fall occurs, providing a safer working environment. Still furthermore, reinforcing the batter 4 before excavating the batter face 5 is considered to be a relatively safe operation.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Remote Sensing (AREA)
  • Geology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Paleontology (AREA)
  • Pit Excavations, Shoring, Fill Or Stabilisation Of Slopes (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
US13/505,647 2009-11-04 2010-11-04 Slope of an Open Cut Mine Abandoned US20120230776A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AU2009905382A AU2009905382A0 (en) 2009-11-04 Improved Slope Of An Open Cut Mine
AU2009905382 2009-11-04
PCT/AU2010/001459 WO2011054035A1 (fr) 2009-11-04 2010-11-04 Pente perfectionnée d'une mine à ciel ouvert

Publications (1)

Publication Number Publication Date
US20120230776A1 true US20120230776A1 (en) 2012-09-13

Family

ID=43969471

Family Applications (1)

Application Number Title Priority Date Filing Date
US13/505,647 Abandoned US20120230776A1 (en) 2009-11-04 2010-11-04 Slope of an Open Cut Mine

Country Status (9)

Country Link
US (1) US20120230776A1 (fr)
EP (1) EP2496773A1 (fr)
JP (1) JP2013509517A (fr)
KR (1) KR20120091288A (fr)
CN (1) CN102597379A (fr)
AU (1) AU2010314803A1 (fr)
CA (1) CA2779674A1 (fr)
RU (1) RU2012122782A (fr)
WO (1) WO2011054035A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103133003A (zh) * 2013-02-25 2013-06-05 中国矿业大学 露天矿端帮靠帮开采方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110924398B (zh) * 2019-10-28 2021-07-23 中交第二航务工程局有限公司 一种保通条件下高强岩质边坡拓宽开挖施工方法
CN113550334A (zh) * 2021-06-30 2021-10-26 中冶成都勘察研究总院有限公司 一种矿山边坡稳定梯级台阶布置方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU735775A1 (ru) * 1973-02-12 1980-05-25 Всесоюзный научно-исследовательский институт горной геомеханики и маркшейдерского дела Способ укреплени уступов
US6299386B1 (en) * 1999-06-09 2001-10-09 R. John Byrne Method and apparatus for a shoring wall
US20020056508A1 (en) * 2000-04-06 2002-05-16 Randel Brandstrom Fiber reinforced rod
US8424852B2 (en) * 2009-01-28 2013-04-23 Benjamin Anson Kit for a barrier system

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2118593B (en) * 1981-12-18 1985-08-29 Sellers G & J Pty Ltd Open cut mining
SU1265331A1 (ru) * 1985-04-23 1986-10-23 Свердловский горный институт им.В.В.Вахрушева Транспортный уступ карьера
JPH0874260A (ja) * 1994-09-05 1996-03-19 Fujita Corp もたれ式擁壁による切土斜面補強法
CN1052525C (zh) * 1997-10-23 2000-05-17 北京矿冶研究总院 一种露天高台阶采矿方法
RU2127809C1 (ru) * 1998-05-12 1999-03-20 Руслан Борисович Юн Способ открытой разработки месторождений р.б.юна
ITMI20032154A1 (it) * 2003-11-07 2005-05-08 Uretek Srl Procedimento per incrementare la resistenza di un volume
CN1217068C (zh) * 2004-02-20 2005-08-31 中国科学院力学研究所 一种边坡加固排桩设计方法
RU2294434C1 (ru) * 2005-09-27 2007-02-27 Акционерная компания "АЛРОСА" (Закрытое акционерное общество) Способ открытой разработки крутопадающих месторождений

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU735775A1 (ru) * 1973-02-12 1980-05-25 Всесоюзный научно-исследовательский институт горной геомеханики и маркшейдерского дела Способ укреплени уступов
US6299386B1 (en) * 1999-06-09 2001-10-09 R. John Byrne Method and apparatus for a shoring wall
US20020056508A1 (en) * 2000-04-06 2002-05-16 Randel Brandstrom Fiber reinforced rod
US8424852B2 (en) * 2009-01-28 2013-04-23 Benjamin Anson Kit for a barrier system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103133003A (zh) * 2013-02-25 2013-06-05 中国矿业大学 露天矿端帮靠帮开采方法

Also Published As

Publication number Publication date
JP2013509517A (ja) 2013-03-14
WO2011054035A1 (fr) 2011-05-12
RU2012122782A (ru) 2013-12-10
KR20120091288A (ko) 2012-08-17
CN102597379A (zh) 2012-07-18
AU2010314803A1 (en) 2012-05-31
EP2496773A1 (fr) 2012-09-12
CA2779674A1 (fr) 2011-05-12

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Date Code Title Description
AS Assignment

Owner name: BHP BILLITON SSM DEVELOPMENT PTY LTD., AUSTRALIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HAILE, ANDREW;REEL/FRAME:028244/0931

Effective date: 20120509

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION