The substantiation
of ways of rock consolidation of seam roof with the help of application of a
roof bolting.
Kravchuk R.N. Gr. MUF
- 96"b"
Master: N. Kasyan;
The relevant role
in an increase in the effectiveness of production (cost reduction of
production, growth(increase) of labour productivity, the safety control both
rhythmicities of activity of mines and ore mines) plays a solution of a problem
of rational attachment and reliable roadway maintenance. Used fix, despite of
high specific consumption of materials, do not content(fit) in some cases to
geological conditions, in which one they are applied, and do not respond the
modern requirements of a further increase in the effectiveness of production. Therefore
now for maintenance of the maintenance-free contents of
developments(manufactures) the creation and intrusion of new designs of
supports having large lift capability and smaller metal consumption(power-to-weight
ratio) is conducted. To number of such supports concern also anchor, which one
will be used not only for attachment of underground mine workings, but also for
holding abrupt mining declines in a high ground terrain and sides of opencasts
at the open mining of mineral resources, and also for the different auxiliary
purposes.
The roof bolting
consists of a system of anchor rods (wood, metallical, concrete, plastic etc.)
consolidated in the drilled contoured development(manufacture) wells and lift
capability, intended for increase, of rocks at the expense of binding and
holding of its(her) separate layers or units depending on a structural
constitution of rocks containing development(manufacture).
The anchor in turn
consists of a rod, lock and strainer. The lock of an anchor serves for
fastening of a rod in rock, and strainer (nut, wedge and т. д.) - for creation in a rod of an anchor of
a preliminary tension with the purpose of reduction(decreasing) development of
rock deformation. In anchors, the rods which one are consolidated on all length
of well, latch the device, and also preliminary tension in rods can miss.
The locks of
anchors place or in steady rocks above than contour of natural equilibrium, or
in layers of rocks migrating with safe speed, providing a stable state of mine
workings.
The lift
capability of rocks with a roof bolting reaches such limits, at which one they
are not blasted under effect of a rock pressure for want of in
development(manufacture) of carrier fix, and are capable only continuously(smoothly)
to hog without a gap.
The anchors are
used by a constant and temporary support, and also for the different auxiliary
purposes. As a permanent support they will be used as independently, and in
combination to other kinds(views) of supports. The roof bolting in a speed key
with and concerns to them with bulkhead supports. Defends rocks from access of
air and prevents their eolation and destruction. Besides having high strength,
considerably enhances(strengthens) a design fix. As a whole in a combined
support executes(designs) a role of a fissile tightening.
The temporary roof
bolting on nature of activity is subdivided on bolstering and enclosuring.
The bolstering
temporary roof bolting is intended for an avoidance of a roof fall of rocks before
exponentation of a permanent support.
In an enclosuring
temporary support the anchors serve for the suspension of safety
overlaps(blockings) shadowing people and machine from falling out chunks from a
roof of development(manufacture).
The anchors will
be used also for strengthening of the mine equipment, suspension of cables,
ventilation and water-supply pipes, repair of mine workings and т. Item.
The perennial case record of a roof
bolting has shown, that this support can be applied in a broad band of rocks on
a stability and their structural constitution as independently, and in
combination to supports of a bolstering type, and in-situ concrete.
Depending on a
structural constitution of rocks of a roof of the form(shape) of
section(cross-section) of development(manufacture) distinguish five main
conditions of its(her) application:
· Laminated
rocks direct or the followings are hanged by anchors to a main roof;
· Different
layers, being cemented by anchors, will derivate a split beam protecting roof
from a roof fall (case "of «cross-link");
· About
each anchor the chunks of fitchery ground nestle to one another, derivating the
strong unit. In this case on perimeter of development(manufacture) with the
help of an anchor the ring of such units bolstering one another, as in an
immovable arch is made;
· In
jointed homogeneous high-power rock the roof bolting protects
development(manufacture) from a fall of separate chunks at deployment of
natural cracks under effect of a rock pressure;
· At
realization on a hardly jointed laminated massif with a contour close
conterminous to a dome of natural equilibrium, the roof bolting protects
development(manufacture) from and emptying of rocks.
300 types of a
roof bolting fastening, distinguished by a way, stuff and design are known from
above.
The typeselection
of a roof bolting depends on a number(series) of the geologic, mine technical
and technological factors. To these factors concern: a constitution and
physical-mechanical characteristics of rocks, degree of a disturbance and of fields, depth of mining, spacing interval
between seams, configuration, assigning and service life of development(manufacture),
condition of its(her) exploitation, consumption, cost, and strength properties of stuffs of a roof
bolting, manufacturability of manufacturing and support setting.
All diversity of
designs can be systematized as follows. As a stuff for manufacturing fix the
polymers, gum are applied an arbor, metal, reinforced concrete. By the form
distinguish one-latch, two-latch, multilatch and anchors. To fastening of anchors in well apply following ways:
mechanical, chemical, explosive; besides for same purpose will use cement
slurry. The locks of anchors are be wedge,
spreader and screw(propeller). On number of rods distinguish one-beam,
two-beam and multibeam anchors. They can be rigid and nonrigid (cable, wire)
with the periodic, round and corrugated structure(profile). The support members
(spacer) can be spherical, flat and curly. For a preliminary tension of anchors
will use a threaded pair in latch or tailpiece and keyings in an installation
site of support members. Support distinguish rigid and yielding, to its(her)
exponentation apply the engine driven and manual ways.
From reduced it is
visible, that the roof boltings about matching with supports of a bolstering
type have large capabilities from the point of view of mechanization of
processes of attachment and usage of strength properties of stuffs fix. It
provides considerable economies of material and labor costs.
It is necessary to
mark, that each phylum of an anchor does not mate in itself of all advantages
intrinsic to this kind(view) fix, and has definite combination of positive
qualities, which one predetermine his(its) rational field of application. At
installation of a field of application of different phylums of anchors to the
count the following factors were received: strength of fastening, operating
characteristic fix, cost of an anchor, manufacturability of his(its)
manufacturing, simplicity of the installation, capability re-usable and
consumption of a stuff.
The problem of
perfecting and designing of anchors gives large attention, as for us, and
abroad.
The perfect designs
metallical, and cemented roof bolts,
and also anchors from the natural, pressed and plasticized timber are built.
In the metallical and wood anchors of heightened
lift capability are designed, the strength of fastening which one in wells
reaches structural limit of a rod on a gap (60 - 180 кN).
With the purpose
of a strength improvement of fastening in wells of wood anchors it is
recommended to establish(set) them in wells with on a tumulus by the given part, and also to consolidate rods with
application of ampulas with a resin and hardener.
For increase of
lift capability of metallical anchors with the sleeve in USA builds their types with two and three sleeves. The
large attention is given to creation of cemented roof bolts with the
prestressed reinforcement.
Now in domestic
and foreign practice more 600 different designs metallical, concrete, plastic, cable
and other types of anchors are known, which one for the first time are
classified.
The roof bolting
is applied worldwide with a developed mining industry: USA, Canada, Great
Britain, Virginiums, Spain, Australia and т. д.
The roof bolting
will be used in a broad band of attachment as dissecting, preforming and other
mine workings, and at an actual mining of mineral resources. The field of
application her(it) in a speed key with other kinds(views) extends fix
(bulkhead, in-situ concrete), and also for the different auxiliary
purposes.
List of the used literature:
1.
Широков А.П. Теория и практика применения анкерной крепи. – М.,
Недра, 1981, 391 с.
2.
Широков А.П. и др. Расчет анкерной крепи для различных условий
применения. - М., Недра, 1976, 207 с.
3.
Широков А.П., Лидер В.А., Дзауров М.А. и др. Анкерная крепь:
Справочник. - М., Недра, 1990, 205 с.
4.
Ташбет Ю. В. Использование анкерной крепи на сланцевых шахтах. –
Уголь, 1983, № 1, с. 24-25.