Abstrict The present invention relates to a tunnel boring machine particularly
a micro-tunnelling machine having a cutting head rotatably mounted
on the end of a housing and being driven by a first motor means
and a rotatable central auger for removal of soil from the cutting
operation mounted in the interior of the housing, the central auger
being driven by a second motor means to allow rotation of the auger
independent of the rotation of the cutting head. The tunnel boring
machine may also be provided with a rock crusher between the cutting
head and the auger to reduce boulders encountered during the tunneling
to a size to be able to be transported by the auger.
Claims The embodiments of the invention in which an exclusive property
or privilege is claimed are as follows:
1. A micro-tunnelling machine comprising a cylindrical housing
having a diameter of about 2 meters or less, the housing having
a cutting head rotatably mounted on the end of the housing and being
driven by a first motor means; a rotatable central auger for removal
of soil from the cutting operation mounted in the interior of the
housing, the central auger being driven by a second motor means
to allow rotation of the auger independent of the rotation of the
cutting head; a rock crusher between the cutting head and the auger
to reduce boulders encountered during the tunneling to a size to
be able to be transported by the auger; and a cone surrounding the
intake end of the central auger, the cone being provided with spaced
apart bars to limit the size of debris capable of entering the central
auger.
2. A micro-tunnelling machine as claimed in claim 1 wherein the
cutting head has crusher bars mounted on an interior surface which
cooperate with the spaced apart bars of the cone to provide a rock
crusher to reduce large rocks to a size capable of entering the
central auger.
3. A tunnel boring machine comprising a cylindrical housing having
a cutting head rotatably mounted on the end of the housing, a rotatable
central auger for removal of soil from the cutting operation mounted
in the interior of the housing, a rock crusher being located between
the cutting head and the auger to reduce boulders encountered during
the tunneling to a size to be able to be transported by the auger
and a cone surrounding the intake end of the central auger, the
cone being provided with spaced apart bars forming part of the rock
crusher to limit the size of debris capable of entering the central
auger.
4. A tunnel boring machine as claimed in claim 3 wherein the cutting
head has crusher bars mounted on an interior surface which cooperate
with the spaced apart bars of the cone to provide the rock crusher
to reduce large rocks to a size capable of entering the central
auger.
Description FIELD OF THE INVENTION
The present invention relates to dry spoil tunnel boring machines
and particularly to dry spoil tunnel boring machines having increased
boring efficiency. The present invention also relates to dry spoil
micro-tunnelling machines having increased efficiency.
BACKGROUND OF THE INVENTION
Various apparatus have been used for removing earth in a tunneling
operation including the use of tunnel boring machines which are
basically augers, to the use of digging machines such as back hoe
type equipment. Tunnel boring machines commonly in use employ a
rotating toothed cutting head at the end of a housing. As the cutting
head rotates, the soil is loosened and passes into the housing where
it is removed. At present there are two commonly employed techniques
for removal of the debris from the tunneling operation, augers for
dry spoil and slurries.
The auger systems use a central auger which rotates with the cutting
head and moves the soil rearwardly and onto a conveyor for removal.
Auger based tunneling machines often use a motor and gear train
in the jacking pit to rotate the auger. Auger systems suffer drawbacks
in some soil types. For example, loose or soft soil may increase
in volume when exposed to air. Thus when drilling in loose soil,
the soil may expand as it enters the cutting head and auger system
and cause flooding of the housing. There have been machines developed
which rely on the use of flood doors or gates to attempt to control
the rate of soil transfer to maintain the pressure balance. Another
problem is encountered in soil containing large rocks, where the
rocks may be too large to enter the auger and may clog the removal
of soil from the cutting head. While some rocks may be able to enter
the auger system, there is still the possibility that they may become
jammed in the auger system.
The other commonly employed method of removing soil involves the
use of slurry systems. In this method the machine uses water to
turn the excavated material into a pumpable fluid. The slurry normally
requires a 15% solid mixture to achieve pumpable characteristics.
Slurry-based machines have many drawbacks especially in colder climates
where the slurry may be at risk of freezing during processing and
disposal. In addition, silicifying materials such as clays take
time and a lot of water to form into a slurry, whereas, sand courses
absorb and disburse the water. In some types of soils the high pressure
water may enlarge the diameter of the tunnel beyond the machine
diameter and cause unexpected cave-ins. Since one must dispose of
both a liquid and a solid waste, contaminated soils are an increasing
environmental problem.
One particular group of tunnelling machines are those known as
micro-tunnelling machines, which typically have diameters in the
range of 2 meters or less, more particularly 1 to 1.5 meters in
diameter. As these machines have very small diameters, they are
generally remotely controlled from the jacking pit. These machines
use a single motor and gear train in the jacking pit to rotate both
the cutting head and auger simultaneously. Cutter head mining power
loss on long drives is tremendous which is often the limiting factor
in determining the length of the drive. Rotation of the cutting
head with the auger also means that head rotation cannot be reversed
as the auger will only move the spoil away from the face when rotated
in one direction.
SUMMARY OF THE INVENTION
The present invention in one aspect relates to a micro-tunnelling
machine having a cylindrical housing with a diameter of about 2
meters or less, the housing having a cutting head rotatably mounted
on the end of a housing and being driven by a first motor means
and a rotatable central auger for removal of soil from the cutting
operation mounted in the interior of the housing. The central auger
is driven by a second motor means to allow rotation of the auger
independent of the rotation of the cutting head.
In another aspect of the invention there is provided a tunnel boring
machine comprising a cylindrical housing having a cutting head rotatably
mounted on the end of the housing and a rotatable central auger
for removal of soil from the cutting operation mounted in the interior
of the housing. A rock crusher is located between the cutting head
and the auger to reduce boulders encountered during the tunneling
to a size to be able to be transported by the auger.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the present invention are shown in the
drawings wherein:
FIG. 1 is a perspective view partly in section of a preferred embodiment
of a micro-tunnelling machine according to the present invention;
FIG. 2 is a side elevation view of the micro-tunnelling machine
of FIG. 1;
FIG. 3 is a front elevation view of the micro-tunnelling machine
of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment of a micro-tunnelling machine according
to the present invention is shown in the figures generally at 10.
The machine 10 has a cylinder housing 12 sized based upon the desired
size of the tunnel, typically in the range of 2 meters or less,
more particularly 1 to 1.5 meters in diameter. At the end of the
housing is located the cutting head 14 which generally includes
cutting bars 16 and flood doors or gates 18 to aid in controlling
the flow into the interior of the housing 12 of the material removed
from the tunnel face. Once the material enters the housing 12 it
is carried away by a central auger 20 to be disposed.
As shown in the figures, the cutting head 14 has a face plate 22
to which the cutting bars 16 and flood gates 18 are attached, inversely
conical side walls 24 and a base plate 26. The cutting head 14 of
the machine 10 illustrated in the figures is provided with four
cutting bars 16 and flood gates 18. However, this number may vary
depending upon the size of the machine 10 and the soil conditions
in which the machine is used. In some circumstances cutting heads
having three cutting bars and flood gates may be appropriate while
in other circumstances more than four bars and gates may be appropriate.
The side wall 24 of the cutting head 14 is provided with a series
of radiating crusher bars 28 to form part of the rock crusher system.
Attached to the base plate 26 of the cutting head 14 is a toothed
ring gear 30 which engages a complementary gear 32 driven by a first
motor 34 for rotation of the cutting head 14. The first motor 34
is attached to an annular base plate 36 attached along its periphery
to the housing 12. A bearing ring 38 is also attached to the annular
base plate 36 and cooperates with the ring gear 30 to form a cage
40 for ball bearings on which the cutting head rotates. A plurality
of seals 42 are provided around the cutting head 14 for sealing
the interior of the housing against passage of dirt and debris.
The central auger 20 is contained within an inner cone 44 which
is fixed against rotation to the annular base plate 36. Inner cone
44 forms part of the rock crusher of the boring machine of the present
invention. The wall of the inner cone 44 is constructed of a series
of spaced apart crusher bars 46 the spacing 48 between the bars
46 regulating the size of rocks which will pass through and into
the central auger system 20 as will be explained further below.
The central auger 20 is rotated within the cone by means a second
motor means in a generally conventional manner separate from the
first motor means 34. In this way, the rotation of the central auger
20 can be controlled independent of the rotation of the cutting
head 14.
The micro-tunnelling machine 10 of the present invention is preferably
capable of articulated steering simultaneously in both the vertical
and horizontal directions. The steering is accomplished by providing
the housing 12 in two parts 12A and 12B, which are connected together
through the use of articulation cylinders 50. Preferably the machine
10 is provided with three or four of these articulation cylinders
50 spaced along the interior circumference of the housing 12. One
end of the articulation cylinder 50 is attached to one part of the
housing 12A and a second end of the articulation cylinder 50 is
attached to the second part of the housing 12B. A ring 52 of reduced
diameter is attached to housing 12B and extends into the interior
of housing 12A. Seals 54 are located between the ring 52 and the
interior of housing 12A to seal against ingress of material into
the interior of the housing 12.
In operation, the first motor means 34 drives the cutting head
14 at a suitable speed through the use of the motor gear 32 and
ring gear 30 to effect removal of material from the face of the
tunnel. Simultaneously the second motor means is utilized to drive
the central auger 20 to remove the material entering the interior
of the cutting head 14. Soils and small rocks or pebbles pass directly
through the spacing 48 between the crusher bars 46 of the inner
cone 44 and into the central auger system 20 to be removed. Rocks
and boulders which are larger than the size of the spacing are crushed
by the rotating crusher bars 28 on the cutting head 14 and the stationary
crusher bars 46 on the inner cone 44. This movement of the rock
or boulder between the two bars reduces the rock to a size which
allows it to pass through the spacing 48 and be removed by the central
auger system. Propulsion of the tunnel boring machine 10 is carried
out in a conventional manner by pipe-jacking technology.
By controlling actuation of the articulation cylinder 50 the cutter
head 14 is capable of articulated steering of up to about two to
three degrees in both the vertical and horizontal directions.
An important factor in the efficiency of tunneling operations is
the maintenance of earth pressure balances. Maintaining earth pressure
balance is directly related to the cutting head, propulsion and
conveyor subsystem design and operations. As the soil pressure varies
over the length of the drive, pressure sensors, in the cutter head
near the face, will monitor the pressure. The thrust force of the
propulsion system, auger rate of rotation and cutting head rate
of rotation can be varied independently based on the soil conditions
encountered. By adjusting the rate of auger rotation, cutting head
rotation and jacking force, pressure reduction of the waste may
take place inside the auger conveyor.
The micro-tunnelling machine of the present invention has two independent
drive trains, one controlling the rate of cutter head rotation and
the second controlling the rate of spoil auger rotation. In this
way the earth pressure balance can be maintained without the use
of slurry. The auger can be rotated at a higher rate of rotation
than the cutting head to permit the spoil to expand inside the auger
while maintaining a balanced pressure at the face of the tunnel.
By driving the cutting head independent of the auger conveyor,
the cutting head is also permitted to rotate in both directions
while maintaining the rotation of the auger to remove spoil. This
can be an advantage when trying to maintain roll attitude and for
navigation around certain obstacles. It also provides for an additional
operational mode when encountering non-standard conditions particularly
difficult boulders that require crushing.
The present invention also provides an auger type tunnel boring
machine having a rock crusher to reduce the size of rocks encountered
in the tunneling operation to a size which can be easily managed
by the central auger. While the crusher bars 28 and 46 which form
the rock crusher are shown in the figures as straight radiating
bars, other structures are possible. For example, the bars 28 or
46 could be provided as curved radiating bars or they could be concentric
circles provided along the depth of the side wall 24 or inner cone
44. The rock crusher of the present invention in addition to being
used with micro-tunnelling machines, may also be used with tunnel
boring machines of any size including those larger than the micro-tunnelling
machines. The use of the rock crusher enables the tunnel boring
machine to operate in diverse soil types with reduced possibility
of the machines auger system being clogged with large spoil.
Although various preferred embodiments of the present invention
have been described herein in detail, it will be appreciated by
those skilled in the art, that variations may be made thereto without
departing from the spirit of the invention or the scope of the appended
claims. |