STABILISATION SYSTEM FOR SOIL SLOPES

SYSTEME DE STABILISATION DES TALUS DE TERRE

Claims

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CLAIMS
1. A method for stabilising soil within a slope having generally less than 45
degrees of inclination, said method comprising:
penetrating a plurality of soil nails into the soil; and
seeding vegetation on a top surface of the soil, the vegetation being
arranged to generate roots which penetrate through the surface into the soil.
2. The method according to claim 1 comprising placing a fibrous cloth over
the soil surface before seeding such that the vegetation is seeded through the
cloth
for retaining the soil at the surface of the slope.
3. A stabilisation system for stabilising soil within a slope having generally
less than 45 degrees of inclination, said system comprising:
a plurality of soil nails, each having a soil penetrating end for penetrating
into the soil and a surface engaging end for engaging a top surface of the
soil; and
an organic facing arranged to cover the top surface of the soil and the
surface engaging end of each soil nail.
4. The system according to claim 3 wherein the organic facing comprises a
mass of organic fibres having a root structure arranged to penetrate into the
soil.
5. The system according to claim 4 wherein there is provided a cover of
fibrous material arranged to seed the mass of organic fibres thereon.
6. The system according to claim 3 wherein there is provided a retaining
wall structure arranged to be mounted on the slope along a crest of the slope.
7. A stabilisation system for stabilising opposing slopes of an embankment
of soil, said system comprising:
a plurality of soil nails, each having a soil penetrating end for penetrating
into the soil and a surface engaging end for engaging a top surface of the
soil;
an organic facing arranged to cover the top surface of the soil and

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surround the surface engaging end of each soil nail;
a pair of retaining wall structures mounted spaced apart on respective
slopes of the embankment adjacent a crest of the embankment; and
a plurality of cross members, each being connected between the pair of
retaining wall structures.

Description

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CA 02271188 1999-OS-06
STABILISATION SYSTEM FOR SOIL SLOPES
FIELD OF THE INVENTION
This invention relates to a system for stabilising soil slopes.
BACKGROUND
On steep slopes having generally less than 45 degrees of inclination,
the prevention of soil erosion is typically accomplished by planting
vegetation on the
surface of the slope. The roots of the vegetation secure the soil at the
surface.
Vegetation alone however does not prevent large shifts of the soil.
The use of nails and other forms of anchors is known for stabilising soil
on vertical faces. Generally these nails are installed with shotcrete or
precast
concrete facings between the nails during the formation of the faces for
retaining the
soil between the nails. There is no known precedent for utilising nails on
existing
slopes having an inclination of less than 45 degrees.
It is an object of the present invention to provide a stabilisation system
for soil slopes which incorporates internal soil slope stability with the
prevention of
surface soil erosion.
SUM MARY
According to a first aspect of the present invention there is provided a
method for stabilising soil within a slope having generally less than 45
degrees of
inclination, said method comprising:
penetrating a plurality of soil nails into the soil; and
seeding vegetation on a top surface of the soil, the vegetation being
arranged to generate roots which penetrate through the surface into the soil.
Preferably the method includes placing a fibrous cloth over the soil
surface before seeding such that the vegetation is seeded through the cloth
for
retaining the soil at the surface of the slope.

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According to a second aspect of the present invention there is provided
a stabilisation system for stabilising soil within a slope having generally
less than 45
degrees of inclination, said system comprising:
a plurality of soil nails, each having a soil penetrating end for penetrating
into the soil and a surface engaging end for engaging a top surface of the
soil; and
an organic facing arranged to cover the top surface of the soil and the
surface engaging end of each soil nail.
The organic facing preferably comprises a mass of organic fibres having
a root structure arranged to penetrate into the soil.
There may be provided a cover of fibrous material arranged to seed the
mass of organic fibres thereon.
There may additionally be provided a retaining wall structure arranged to
be mounted on the slope along a crest of the slope.
According to a further aspect of the present invention there is provided a
stabilisation system for stabilising opposing slopes of an embankment of soil,
said
system comprising:
a plurality of soil nails, each having a soil penetrating end for penetrating
into the soil and a surface engaging end for engaging a top surtace of the
soil;
an organic facing arranged to cover the top surface of the soil and
surround the surface engaging end of each soil nail;
a pair of retaining wall structures mounted spaced apart on respective
slopes of the embankment adjacent a crest of the embankment; and
a plurality of cross members, each being connected between the pair of
retaining wall structures.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate an exemplary

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embodiment of the present invention:
Figure 1 is a cross sectional view of a soil slope with the stabilisation
system.
Figure 2 is top plan view of the stabilisation system.
Figure 3 is an enlarged view of a portion of Figure 1.
DETAILED DESCRIPTION
Referring to the accompanying drawings, there is illustrated a
stabilisation system generally indicated by reference numeral 10 for
stabilising soil
slopes of a railway embankment. The system 10 is adapted for installation on
existing
slopes 12 of an embankment 14 for stabilising the internal soil of the slopes
and for
preventing erosion of the surface soil. The system is particularly suitable
for use on
slopes having generally less than 45 degrees of inclination.
The system 10 includes a plurality of soil nails 14 which are penetrated
into a top surface 16 of the slope in a staggered pattern. The nails 14 are
elongate
rigid members having any one of numerous different types of cross sections.
The
nails each include a penetrating end 18 arranged to penetrate into the soil
and a
surface engaging end 20 arranged to be secured against the top surface 16 of
the
slope.
The surface engaging end 20 includes a portion of increased diameter
for supporting a washer 22 adjacent the top surface 16 of the soil. The nails
extend
through the soil past an existing or potential failure plane 24 in the soil
for providing
internal soil stability to the slope.
The nails are inserted into the soil by percussion, pushing, turning or
vibrating. Alternatively, the nails may be inserted into pre-made holes. The
nail
strength, length, diameter and spacing are selected based upon the desired
degree of
improvement through an engineering design. Nails are typically 25 to 50
millimetres

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in diameter and 2 to 6 metres long.
A geosynthetic layer 26 is placed across the top surface 16 of the soil
and the surface engaging end of each nail for preventing erosion of surface
soils. The
geosynthetic layer is a cloth of fibrous material having a high tensile
strength. The
use of a geosynthetic layer is a known practice in construction on soft
terrain for
adding structural support to the soil of the terrain.
Vegetation is seeded onto the geosynthetic layer 26 such that an
organic mass of roots extends through the layer and penetrates into the soil.
The
plant root mass is selected based on the desired degree of improvement through
engineering design. The vegetation is typically selected to extend to a depth
of 100 to
400 millimetres into the soil.
A retaining wall structure 28 is mounted on each slope 12 of the
embankment, adjacent a crest 30 of the embankment. Each retaining wall
structure
28 includes an elongate timber 32 extending longitudinally along the
embankment
adjacent the crest.
The timbers 32 are parallel and spaced apart along the crest. A plurality
of concrete anchors 34 are mounted along an outer face 36 of the timbers 32
for
securing the timbers in place. Each anchor is an L-shaped member having an
upright
portion 38 engaging the outer face of the timber and a lateral portion 40
extending
laterally inward adjacent a bottom face of the timber. A pair of the soil
nails 14 are
inserted through respective apertures in each anchor 34 for securing the
anchor to the
embankment at spaced positions along the timber.
Each anchor 34 is secured to a corresponding one of the anchors
adjacent the opposing timber 32 by a rod 42. Each rod 42 is fastened to the
corresponding pair of anchors 34 at respective ends of the rod.
A space 44 defined between the timbers is filled with gravel 46 to allow

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drainage of water and prevent water collection at the crest of the embankment.
The
gravel 46 surrounds the rods 42 extending across the space 44 between
corresponding anchors 34.
A railway 48 is mounted on the crest of the embankment. The railway
48 includes a plurality of rail ties 50 embedded into the gravel. The rail
ties 50 are
parallel and spaced apart along the crest of the embankment. A pair of rails
52 are
mounted on the rail ties 50 parallel and spaced apart.
While one embodiment of the present invention has been described in
the foregoing, it is to be understood that other embodiments are possible
within the
scope of the invention. The invention is to be considered limited solely by
the scope
of the appended claims.

Representative Drawing