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WO2017127900A1 - Élément de cadre porteur et agencements de cadre porteur - Google Patents

Élément de cadre porteur et agencements de cadre porteur Download PDF

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Publication number
WO2017127900A1
WO2017127900A1 PCT/AU2017/050076 AU2017050076W WO2017127900A1 WO 2017127900 A1 WO2017127900 A1 WO 2017127900A1 AU 2017050076 W AU2017050076 W AU 2017050076W WO 2017127900 A1 WO2017127900 A1 WO 2017127900A1
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WO
WIPO (PCT)
Prior art keywords
crib
notches
members
layers
elements
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.)
Ceased
Application number
PCT/AU2017/050076
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English (en)
Inventor
Jason HORNE
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.)
Hoan Holdings Pty Ltd
Original Assignee
Hoan Holdings Pty Ltd
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 AU2016900296A external-priority patent/AU2016900296A0/en
Application filed by Hoan Holdings Pty Ltd filed Critical Hoan Holdings Pty Ltd
Priority to AU2017212154A priority Critical patent/AU2017212154A1/en
Publication of WO2017127900A1 publication Critical patent/WO2017127900A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D15/00—Props; Chocks, e.g. made of flexible containers filled with backfilling material
    • E21D15/48—Chocks or the like

Definitions

  • the present invention relates to a crib element and crib arrangements for forming supports in different situations including in underground mines.
  • Cribs are widely used in underground mines to provide yielding support for the hanging wall or roof of mine workings. They are usually constructed from lengths of timber, commonly referred to as chocks.
  • the chocks are arranged in layers, with a series of parallel chocks in each layer and with the chocks in alternate layers being at right angles to the chocks in the layers above and below.
  • the layers are assembled sequentially on the footwall or floor of the mine working, and a sufficient number of layers are assembled for the crib to extend to a level close to the roof. Any gap between the uppermost layer and the roof can be taken up by insertion of timber wedges.
  • each chock in the pack has one or more bricks or blocks, typically cementitious or of timber, fixed to it at a predetermined position along its length.
  • the bricks are positioned between the chock-on-chock bearing points to transfer load to the chocks below.
  • natural sawn lumber is generally cut from different sections of a log in relation to different angles relative to the growth rings. This creates pieces of lumber with different strengths stemming from the different cut sections. Some of the cuts are known as half sawn, back sawn, quarter sawn and the like. These different cut scores substantially different strengths in timber pieces depending on how they are sawn from the natural log. Use of natural sawn lumber in cribbing therefore leads to substantially different strengths in the different cribbing elements depending upon how the grain in each cribbing element lies and to the orientation of the cribbing element.
  • Each outer plate element is attached to a surface of the centre elongate element using one or more fastening means, such as nails, screws, bolts and/or adhesive and the outer plate element wood grain direction is aligned transversely to the grain direction in the centre elongate element.
  • fastening means such as nails, screws, bolts and/or adhesive
  • the wooden support elements of United States Patent No. 7841805 are purported to be lightweight, the wooden support elements are still vulnerable to the
  • the cribs of United States Patent No. 7841805 also rely on the correct arrangement of the centre elongate element and the at least two outer plate elements in each layer. Since the centre elements and the outer elements have different wood grain directions, the centre elements and the outer elements are not interchangeable. Furthermore, the outer elements are required to be attached to the centre elements which adds to the assembly time of the crib.
  • the present invention is directed to a crib element and crib arrangements, which may at least partially overcome at least one of the abovementioned disadvantages and/or provide the consumer with a useful or commercial choice.
  • the present invention in one form, resides broadly in a crib element comprising a unitary engineered wooden member having an upper edge and a lower edge.
  • engineered wood also called composite wood, man-made wood, or manufactured board
  • engineered wood also called composite wood, man-made wood, or manufactured board
  • derivative wood products which are manufactured by binding or fixing the strands, particles, fibres, or veneers or boards of wood, together with adhesives, or other methods of fixation to form composite materials.
  • the present invention resides in a crib element including a unitary engineered wooden member having at least a pair of notches in an upper edge and at least a pair of notches in a lower edge to form a central web therebetween, each notch spaced from an end of the member such that the notches have a portion with a depth sufficient to allow the upper edge of the member to abut a lower edge of a second, parallel member sandwiching the central web of at least a third member in respective, aligned notches of the first and second members.
  • the present invention resides in a crib element including a unitary engineered wooden member having at least a pair of notches in an upper edge and at least a pair of notches in a lower edge to form a central web therebetween, each notch spaced from an end of the member such that the notches have a portion with a depth of at least one quarter of the dimension between the upper edge and the lower edge of the member.
  • the present invention resides in a crib arrangement including a number of unitary engineered wooden chock members, each chock member having at least a pair of notches in an upper edge and at least a pair of notches in a lower edge to form a central web therebetween, each notch spaced from an end of the member, the chock members provided in layers with two chock members to each layer, alternating layers being offset perpendicularly to one another such that the notches of the chock members in a first layer have a portion with a depth sufficient to allow the upper edge of the chock members in the first layer to abut a lower edge of the chock members in a third layer, parallel to the first layer sandwiching the central web of the chock members in a second layer in respective, aligned notches of the chock members of the first and third layers.
  • the present invention will preferably use a unitary, engineered wooden member, preferably a laminated wood.
  • Laminated wood has a variety of different names, but "plywood” is used most frequently.
  • "Plywood” is normally defined as an assemblage of wood veneers bonded together to produce a flat sheet. Typically the veneers in plywood are positioned with the grains of adjoining veneers at right angles to each other although this does not need to be the case.
  • the wood chosen for the manufacture of the laminated wooden member according to a preferred embodiment of the present invention will normally be a softwood as distinguished from a hardwood. However, some hardwoods which are on the soft end of the hardwood scale such as poplar may also be used. Preferred softwoods include conifer species such as fir and pine and radiata pine is particularly preferred.
  • the grade quality of plywood ranges from A to D with A being the highest quality having imperfections removed and D being the lowest quality with defects such as knots and splits being acceptable in any one or more of the layers.
  • gluebonds are defined and specified in Australian Standard AS2754.1 Adhesives for Plywood Manufacture.
  • the bond types are - A, B, C and D, in decreasing order of durability under conditions of full weather exposure.
  • Type A bond is produced from a phenol formaldehyde (PF) resin, which preferably sets permanently under controlled heat and pressure. It forms a permanent bond that will not normally deteriorate under wet conditions, heat or cold. It is readily typically recognisable by its black colour.
  • PF phenol formaldehyde
  • the formaldehyde adhesives typically used in plywood or laminated wood manufacture are thermosetting and will preferably not replasticise under reheating as do thermoplastic adhesives such as elastomeric wall board adhesives and PVA.
  • Phenolic Type A bonds have particularly low formaldehyde emission, of between 0.00 to 0.03 ppm.
  • poplar can be used according to the present invention, the situations in which it is used are less common than those for the use of radiata pine. This is typically because of the particular structure of the wood. Poplar is less likely to form a satisfactory Type-A bond.
  • White poplar can be used but it has a different cell wall structure and using Phenyl Formaldehyde glue typically takes a lot longer under heat and pressure during the curing stage in the manufacturing process to impregnate the veneers used to form the laminated wood member therefore driving up processing costs considerably and being time consuming.
  • Paint or sealing of the laminated wood member can be used to limit or stop emissions but it is preferred that a Type-A bond is formed with its attendant lower emissions.
  • Phenyl Formaldehyde adhesives are standard for exterior bonds, combined with visually inspected and manicured high grade whole veneers used giving the plywood its structural grade category.
  • Type A bonded exterior plywood should be treated against fungal attack and the surface should be finished with paint or water repellents to minimise mechanical surface checking. This is not necessarily a consideration for underground
  • Structural Laminated Veneer Lumber manufactured to AS/NZS 4357.0
  • Structural Laminated Veneer Lumber is an assembly of veneers laminated with a Type A phenolic resin.
  • the grain direction of the veneers is in the longitudinal direction. The process used to manufacture LVL is defined and explained in a number of references including the Australian Standard.
  • LVL or plywood formed from a softwood such as radiata pine even though classified as softwood or the less preferred poplar, provide the required strength and toughness characteristics as well as sought after emissions characteristics when a Type-A adhesive is used to make this particular type of LVL or plywood surprisingly useful in crib formation for use in underground mines.
  • the LVL or plywood member of the preferred embodiment will normally be laminated first and then cut or routed to the finished shape.
  • the shape of the crib (chock) elements themselves, there are many different shapes that can be used.
  • the shape of the chock elements will normally be substantially planar and rectangular in cross sectional shape with a number of notches.
  • the notches can have any shape and/or location. It is preferred that a uniform shape is used for all notches. It is further preferred that the location of the notches be symmetrical (both longitudinally about a transverse midline of the member and transversely about a longitudinal midline of the member) and the same on all chock elements for ease of manufacture and assembly of the crib.
  • the joint formed between members in the system of the present invention can have any configuration and may involve the notches formed in one edge of the member differing in configuration from those in another, normally opposite edge. Normally, if provided in a non-uniform configuration, the notches formed in one edge of the member will preferably have notches of a corresponding configuration provided on the opposite edge. Alternatively, there may be two sets of members, each set of members to be used in alternating levels of the crib, one set with notches of a first configuration and the other set with notches of a second configuration corresponding to those of the first configuration to allow offset members to engage with one another.
  • the unitary engineered wooden member of the crib element may further comprise strands, particles, fibres, veneers or layers of one or more of the following amongst the plurality of wood veneers or layers: one or more plants; one or more grasses, such as bamboo; metal, such as aluminium or steel; fibreglass; carbon fibre; other synthetic materials, such as plastics.
  • the crib element may comprise a reinforcing layer on at least one outer surface of the crib element.
  • the reinforcing layer can be selected from the following: fibreglass; carbon fibre; metal, such as aluminium.
  • the reinforcing layer can provide additional strength and can assist in preventing buckling of the crib element.
  • the present invention resides in a kit comprising a plurality of the aforementioned crib elements for coupling together to form the crib arrangement.
  • Figure 1 is an isometric view of a prior art crib arrangement showing the forces on a four-pointer crib.
  • Figure 2 is an isometric view of a chock according to a prior art configuration which may be used according to a preferred embodiment of the present invention.
  • Figure 3 is a front elevation view of the chock illustrated in Figure 2.
  • Figure 4 is an isometric exploded view of a crib arrangement formed using the chocks illustrated in Figures 3 and 4.
  • Figure 5 is an isometric view of a cross lap joint which may be used according to a preferred embodiment of the present invention.
  • Figure 6 is an isometric view of the member designated "Y" in Figure 5.
  • Figure 7 is an isometric view of a cogged joint which may be used according to a preferred embodiment of the present invention.
  • Figure 8A is an elevation view of a chock according to a preferred embodiment of the present invention.
  • Figure 8B is an isometric view of the chock illustrated in Figure 8A.
  • Figure 9 is a photograph of a test rig used to test samples in a test program explained below.
  • Figure 10 is an isometric view from above of 6 test specimens sampled in the test program.
  • Figure 11 is a front elevation view of test sample LVL A after the testing.
  • Figure 12 shows a load displacement curve for test sample LVL A.
  • Figure 13 is a front elevation view of test sample LVL B after the testing.
  • Figure 14 shows a load displacement curve for test sample LVL B.
  • Figure 15 is a front elevation view of test sample LVL C after the testing.
  • Figure 16 shows a load displacement curve for test sample LVL C.
  • Figure 17 is a front elevation view of test sample LVL D after the testing.
  • Figure 18 shows a load displacement curve for test sample LVL D.
  • Figure 19 is a front elevation view of test sample Plywood 1 after the testing.
  • Figure 20 shows a load displacement curve for test sample Plywood 1.
  • Figure 21 is a front elevation view of test sample Plywood 2 after the testing.
  • Figure 22 shows a load displacement curve for test sample Plywood 2.
  • Figure 23 shows a load displacement curve for Test A - a plywood crib arrangement according to a preferred embodiment of the present invention.
  • Figure 24 shows a load displacement curve for Test B - a plywood crib arrangement according to a preferred embodiment of the present invention.
  • a crib element also referred to herein as a chock, or chock member
  • crib arrangement using a plurality of crib elements is provided.
  • the chock of the preferred embodiment comprises a unitary laminated wooden member 10 having at least a pair of notches 11 in an upper edge 12 and at least a pair of notches 13 in a lower edge 14 to form a central web 15 therebetween.
  • Each notch 11, 13 is spaced from an end 17 of the member 10.
  • the configuration of the embodiment illustrated in Figures 8A and 8B has generally the same shape and configuration as the member illustrated in Figures 2 and 3.
  • the notches 11, 13 comprise curved wall portions 54 between vertical and horizontal wall portions of the notches. Curved wall portions 54 can facilitate interlocking of the unitary laminated wooden members 10 in the crib arrangement.
  • a plurality of chock members 10 are provided in layers with two chock members to each layer to form a crib arrangement. Alternating layers are offset perpendicularly to one another such that the notches 11, 13 of the chock members in a first layer
  • A have a portion with a depth sufficient to allow the upper edge 12 of the chock members in the first layer A to abut a lower edge 14 of the chock members in a third layer C, parallel to the first layer A, sandwiching the central web 15 of the chock members in a second layer B in respective, aligned notches of the chock members of the first layer A and the third layer C.
  • the laminated member 10 is manufactured of wood of the type having scientific name Pinus Radiata (common name radiata pine). Radiata pine is an abundant plantation timber, preferably sourced from sustainably managed forests compatible with Phenyl Formaldehyde adhesive for the creation of a structural plywood member.
  • the adhesive preferred is a Phenyl Formaldehyde adhesive or resin.
  • the common Australian name is Type-A bond permanent glue which is a thermosetting adhesive with an E0 emissions standard.
  • the Phenyl Formaldehyde adhesive or resin is water proof. Once cured, the molecule links cannot be reversed. Heat, water, and chemicals have no effect on the glue.
  • the Phenyl Formaldehyde adhesive or resin is compatible with the radiata pine for the manufacture of engineered wood products.
  • the LVL or plywood member of the preferred embodiment will normally be laminated first and then cut or routed to the finished shape.
  • the shape of the chock elements 10 will normally be substantially planar and rectangular in cross sectional shape with a number of notches.
  • the notches can have any shape and/or location. It is preferred that a uniform shape is used for all notches as illustrated in Figures 2 and 3. It is further preferred that the location of the notches be symmetrical (both longitudinally about a transverse midline of the member and transversely about a longitudinal midline of the member) and the same on all chock elements for ease of manufacture and assembly of the crib.
  • the joint formed between members in the system of the present invention can have any configuration and may involve the notches formed in one edge of the member differing in configuration from those in another, normally opposite edge. Normally, if provided in a non-uniform configuration, the notches formed in one edge of the member will preferably have notches of a corresponding configuration provided on the opposite edge. Alternatively, there may be two sets of members, each set of members to be used in alternating levels of the crib, one set with notches of a first configuration and the other set with notches of a second configuration corresponding to those of the first configuration to allow offset members to engage with one another.
  • Examples of joint configurations that may find use in the present invention are the cross lap joint illustrated in Figures 5 and 6 where the notch 16 is provided in both members X, Y and then positively locates the members X, Y relative to one another when the notches 16 in the respective members are aligned.
  • a cogged joint pattern is another joint configuration, as illustrated in Figure 7, in which the notch 16 in member X is located over the portion identified as 50 in the adjacent member Y. This configuration requires that the notches 16 in the upper edge are either that depicted by reference numeral 16 or that identified by reference numeral 50 and the other of the two is provided on the adjacent member.
  • Different combinations can be used on the chock 10 with the same or different notches used at either end of the member or in the upper and lower edge provided that the pattern is repeatable when assembling the crib.
  • the plies/veneers in the laminated member of the preferred embodiment are orientated so that the grain direction in one ply is rotated 90 degrees relevant to adjacent plies. Solid wood is 20 times stronger along the grain than across and generally breaks easily along the grain. By cross laminating the veneers, this greatly increases the strength, shear resistance and load sharing capabilities in both directions.
  • Solid wood shows significant changes in the transverse direction to grains, but contraction and swelling on the longitudinal plane are usually limited.
  • a well-balanced manufacturing of plywood with direction of the grains of adjacent veneers at a right angle tends to balance tension and increases strength and dimensional stability when more layers are added. This makes the plywood of the present invention virtually split proof and it returns to original dimensions if wetting and drying occurs with no shrinkage.
  • LVL usually has unidirectional veneers, that is all veneers are parallel to the beam length and there are no cross veneers.
  • Plywood comprising differently oriented grain directions in adjacent veneers
  • LVL aligned grain directions in adjacent veneers
  • the structural plywood lumber for the chock element 10 in under ground mine cribbing manufactured as described above is an engineered alternative to the current natural sawn species used world wide in Longwall and under ground coal mining with particular advantages.
  • the aim of the testing program was to obtain the maximum compression load carrying capacity of six different engineered composite timber specimens provided.
  • the tests provide a comparison of compression load carrying capacity of different engineered composite timber loaded in different orientations of laminations, with or without distortion or deformation.
  • An MTS universal servo-controlled testing machine of 1 MN capacity was used for the compression testing (Figure 9). Load and displacements were measured for each specimen. Maximum displacement was set at 55mm for all the tests except for sample LVL A. The displacement limit for the MTS machine is 60mm. LVL A was the first specimen to be tested, and as the range of displacement was not known, the displacement limit was set to 25mm for LVL A. After testing LVL A, the displacement limit was increased to 55mm for all the remaining tests.
  • Specimen dimensions and mass are given in Table 1. Specimens for testing are shown in Figure 10.
  • the species of the timber is pinus radiata (scientific name) - radiata pine (common name).
  • the timber was grown in the southern hemisphere from sustainably managed plantation forests with Forestry Stewardship Council (FSC certification).
  • FSC certification Forestry Stewardship Council
  • Specimen Plywood 1 started yielding at the load of 48kN and corresponding displacement of 3.3mm. The maximum load attained was 157 kN at corresponding displacement of 55 mm. The loading was stopped at the displacement of 55mm. Specimen after the test is shown in Figure 19 and the load-displacement curve is shown in Figure 20.
  • Tests A and B were subsequently conducted by the National Institute for
  • NIOSH Occupational Safety and Health
  • MRS Mine Roof Simulator
  • Test A was conducted on a crib arrangement comprising preformed plywood crib elements having dimensions 1000mm x 150mm x 75mm and a mass of approximately 5.44kg (121bs).
  • the plywood crib elements comprise notches 11, 13 towards the ends of the crib elements as described herein to allow for full contact between the crib elements in adjacent layers.
  • the notched plywood crib elements improve crib stability by completely interlocking the crib elements and the full contact greatly improves support capacity.
  • the resulting crib arrangement had a height of 2,945 mm.
  • the MRS utilised displacement control with a vertical displacement rate of 12.7-mm/min (0.5-in/min).
  • Test A the plywood crib arrangement is placed in the centre of the MRS.
  • the lower platen is raised to establish a full roof and floor contact creating a uniform loading on the crib arrangement.
  • a controlled vertical displacement at a rate of 0.5-in/min (12.7-mm/min) is applied to the crib arrangement by the MRS to simulate convergence of the mine roof and floor.
  • the applied loading is measured as a function of time and vertical displacement to determine the performance of the crib arrangement. Convergence continues until the crib arrangement becomes unstable, sheds load until the support load is inadequate, or the full 24-in (609.6-mm) stroke of the MRS is reached.
  • a load-displacement curve for Test A is shown in Figure 23.
  • the plywood crib arrangement provided a fairly stiff initial response. After yielding, the plywood crib arrangement continued to increase its support load capacity. There was no significant loss of stability or capacity during the yielding process. Failure mode was due to shear failure of the plywood crib elements. At approximately 16 inches (406mm) of
  • the plywood crib arrangement performed well and the arrangement was able to support a large load for over 16 inches (406mm) of displacement at a high load capacity of over 400kips (18 It).
  • the crib arrangement was observed to have a minor crack in one of the crib elements at 16 inches of displacement, but failed quickly at 17 inches (432mm) of displacement. Nonetheless, the plywood crib arrangement of Test A exceeds industry standards.
  • the yielding of the plywood crib arrangement of Test A also provides a "telltale" sign well in advance of failure of the crib arrangement.
  • Test B was conducted on a crib arrangement comprising the same type of preformed plywood crib elements as used in Test A and having the same dimensions of 1000mm x 150mm x 75mm and the same mass of approximately 5.44kg (121bs).
  • the crib arrangement had a height of 2,941 mm.
  • the same MRS machine was used as in Test A and utilised the same displacement control with a vertical displacement rate of 12.7-rnm/min (0.5-in/min).
  • a 2: 1 verticahhorizontal convergence test was conducted.
  • a load-displacement curve for Test B is shown in Figure 24.
  • the plywood crib arrangement provided a fairly stiff initial response. After yielding, the plywood crib continued to increase its support load capacity. There was no significant loss of stability or capacity during the yielding process. Failure mode was due to shear failure of the plywood crib elements. At approximately 13.6 inches (345mm) of displacement a crack developed on one of the plywood crib elements 1 ⁇ 4 of the distance down the height of the crib arrangement on the rear of the crib arrangement. The crack continued to increase in size until the test was stopped to prevent the crib arrangement from collapsing. This failure behaviour was similar to the failure of the crib arrangement in Test A.
  • the plywood crib arrangement performed well and it was able to support a large load for over 16 inches (406mm) of displacement at a high load capacity of over 394kips (179t).
  • the crib arrangement was observed to have a minor crack in one of the crib elements at 16 inches of displacement but failed quickly at 17 inches (432mm) of displacement. Nonetheless, the plywood crib arrangement of Test B exceeds industry standards and demonstrates the plywood crib arrangement of the present invention can withstand horizontal as well as vertical loads.
  • the yielding of the plywood crib arrangement of Test B also provides a "telltale" sign well in advance of failure of the crib arrangement.
  • the unitary engineered wooden member 10 of the crib element can further comprise strands, particles, fibres, veneers or layers of one or more other materials amongst the plurality of wood veneers or layers.
  • other materials that can be included are one or more other plants, one or more grasses, such as bamboo, due to its high tensile strength, one or more metals, such as aluminium or steel, fibreglass, carbon fibre and/or other synthetic materials, such as plastics.
  • the mode of inclusion of the one or more other materials in the unitary engineered wooden member 10 of the crib element will depend on the type and number of different other materials.
  • the unitary engineered wooden member 10 of crib element can comprise a reinforcing layer 52 on at least one outer surface of the crib element, as shown in Figure 7.
  • the reinforcing layer 52 can be selected from the following: fibreglass; carbon fibre; metal, such as aluminium.
  • the crib elements comprising the at least one reinforcing layer are arranged in the crib arrangement such that the reinforcing layer is on the outside of the crib arrangement.
  • the reinforcing layer can provide additional strength and can assist in preventing buckling and/or shearing of the crib element when under load in the crib arrangement.
  • the crib element can be coated in a layer of fibreglass on one or more outer surfaces.
  • the reinforcing layer 52 can be in the form of a metal sheet affixed by any suitable means to an outer surface of the crib element. In some embodiments of the present invention, the reinforcing layer 52 is provided on more than one outer surface of the crib element.
  • the crib elements and crib arrangements according to embodiments of the present invention address or at least ameliorate one or more of the aforementioned problems of the prior art.
  • the unitary engineered wooden crib elements and crib arrangements constructed therefrom according to embodiments of the present invention are lightweight compared with, for example, natural sawn timber elements and therefore are easier to manoeuvre, thus minimising safety issues when assembling and disassembling the crib, particularly to the heights typically required for crib arrangements.
  • some conventional hardwood crib elements are 30- 40% heavier than the unitary engineered wooden crib elements according to some embodiments of the present invention.
  • the uniformity of shape and composition of the crib elements allows the crib elements to be interchangeable, thus avoiding the need to selectively arrange crib elements having different shapes and/or compositions and thus facilitating the ease and efficiency of construction of crib arrangements according to the present invention.
  • the provision of notches in the crib elements prevents sideways slippage of crib elements in adjacent layers.
  • the provision of notches also avoids the need for the crib elements to be fastened together, which further facilitates the ease and efficiency of assembly and disassembly of crib
  • the unitary engineered wooden crib elements also avoid the aforementioned drawbacks associated with defects in timber and the natural variations and different strengths of natural sawn timber.
  • the crib elements and crib arrangements according to embodiments of the present invention exceed industry standards in terms of the loads that they can support.
  • the yielding of the plywood crib arrangement under load provides an early warning sign well in advance of failure of the crib arrangement thus providing time for personnel to vacate the surrounding area.
  • the inclusion of a reinforcing layer on at least one outer surface of the crib element can further assist in preventing buckling and shearing of the crib element.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)

Abstract

L'invention concerne un élément de cadre porteur comprenant un élément en bois construit unitaire ayant, dans un mode de réalisation préféré, au moins une paire d'encoches dans un bord supérieur et au moins une paire d'encoches dans un bord inférieur pour former une bande centrale entre elles, chaque encoche étant espacée d'une extrémité de l'élément de telle sorte que les encoches ont une partie avec une profondeur suffisante pour permettre au bord supérieur de l'élément de venir en butée contre un bord inférieur d'un deuxième élément parallèle prenant en sandwich la bande centrale d'au moins un troisième élément dans des encoches alignées respectives des premier et deuxième éléments pour former un agencement de cadre porteur.
PCT/AU2017/050076 2016-01-29 2017-01-30 Élément de cadre porteur et agencements de cadre porteur Ceased WO2017127900A1 (fr)

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AU2017212154A AU2017212154A1 (en) 2016-01-29 2017-01-30 A crib element and crib arrangements thereto

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AU2016900296 2016-01-29
AU2016900296A AU2016900296A0 (en) 2016-01-29 A Crib Element and Crib Arrangement Thereto

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
PL448202A1 (pl) * 2024-04-05 2025-10-06 Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie Kaszt górniczy i sposób wytwarzania kasztu górniczego

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5746547A (en) * 1995-10-19 1998-05-05 Strata Products, Inc. Mine support cribs
GB2335678A (en) * 1999-03-09 1999-09-29 George Raymond Sharp Crib member for mine support crib
US6352392B1 (en) * 1999-10-08 2002-03-05 Strata Products (Usa), Inc. Mine roof support crib having only two or three planes, and method
WO2003031773A2 (fr) * 2001-10-10 2003-04-17 Strata Products (Usa), Inc. Cadre de soutenement leger de toit de mine et procede
US7841805B2 (en) * 2007-09-12 2010-11-30 Board Of Trustees Of Southern Illinois University Engineered composite wooden crib for use as a mine support

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US5746547A (en) * 1995-10-19 1998-05-05 Strata Products, Inc. Mine support cribs
GB2335678A (en) * 1999-03-09 1999-09-29 George Raymond Sharp Crib member for mine support crib
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US7841805B2 (en) * 2007-09-12 2010-11-30 Board Of Trustees Of Southern Illinois University Engineered composite wooden crib for use as a mine support

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PL448202A1 (pl) * 2024-04-05 2025-10-06 Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie Kaszt górniczy i sposób wytwarzania kasztu górniczego

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