Slope failure repair using tyre bales at Interstate Highway
30, Tarrant County, Texas, USA
W. Prikryl1, R. Williammee2 & M.G. Winter3
1TEAM Consultants Inc., 2970 South Walton Walker Boulevard, Dallas, TX 75211, USA
2Fort Worth District, Texas Department of Transportation, P.O. Box 6868, Fort Worth, TX 76115, USA
3TRL Limited, Sighthill Campus, Sighthill Court, Edinburgh, EH11 4BN, UK
The remediation of soil cut slope instability in
Texas has traditionally been achieved using
conventional methods. However, in early 2002
an alternative approach was taken to achieve
the remediation of a failed slope using tyre bales, which
are blocks of compressed whole post-consumer tyres.
This paper describes the construction of the repair, the
comparative retrospective analysis that was carried out
to determine the likely performance of such slope repairs,
and visual observations made around two years after
construction. Specific lessons are drawn from the experience
gained from this work.
Keywords: slope stability, waste management, highways,
remediation
The remediation of soil cut slope instability in Tarrant
County, Texas has conventionally been achieved using
existing or imported soils, with or without modification
by hydraulic binders and often in conjunction with an
‘H’-beam wall, in order to minimize costs and construction
time. More recently consideration has been given to
the use of tyre bales as a partial replacement for soil fill.
This approach is considered likely to significantly improve
the subsequent long-term stability of the repair,
while also providing the benefit of reusing waste tyres.
This is especially significant where the in-situ soils comprise
high plasticity clays, which may be marginally
suitable for such applications, highly moisture sensitive
and inherently unstable. Surface or groundwater seepage
also may be a contributing factor to slope instability as
this region routinely experiences high intensity storms.
In mid-2002 the opportunity was taken to conduct an
informal trial remediation of such a slope failure using
tyre bales as a replacement for the low quality, high
plasticity fill derived from in-situ material. It should be
noted that the precise date of failure is not known, but
the aerial photograph in Figure 1 is dated February 2001
and so failure may be assumed to have occurred at some
time prior to that date.
Tyre bales comprise around 100 or more whole car
tyres (110 to 115 in the UK due to the prevalence of
smaller vehicles and tyres) compressed into a lightweight
block (c. 0.7 Mg/m3), measuring 60$50$30$
(1.52 m1.27 m0.76 m). The completed tyres bales
have a porosity of around 50% or more and a permeability
of approximately 0.4 m/s (Simm et al. 2004)
that makes them ideal for drainage applications and
a bale-to-bale ϕ# of around 36o for dry conditions
(Zornberg 2004). Their drainage properties will thus
make an important contribution to any increases in the
stability of the slope observed.
Failure, remediation and observed
performance
Failure
Interstate Highway 30 (IH30) runs between Dallas and
Fort Worth in Texas and it was a portion of the cut
slope adjacent to the east bound lanes of IH30 west
of Oakland Boulevard that failed. The length of the
failed slope area was approximately 150# (46 m) and the
original slope height reached 20# (6.1 m) at a constant
slope of 1 in 3 (approximately 18o). The failure appears
to have been typical of those experienced in the general
vicinity. Heavy clay soils tend to lose shear strength with
time through weathering and usually, although not
always, fail during or after periods of extended and/or
intense rainfall. Climatic factors are considered severe in
this area and moisture sensitive clay soils may fail at
slope angles as low as 10o (around 1 in 5.7).
Fig. 1. Aerial photograph dated February 2001 showing the
slope failure. The slope faces approximately north (courtesy of
United States Geological Survey, borehole positions added by
authors).
Quarterly Journal of Engineering Geology and Hydrogeology, 38, 377–386 1470-9236/05 $15.00 2005 Geological Society of London
