It ought to be pointed out that only the second (variable) method is safe. The
danger of the first method is that you end up providing adequate reinforcement
only for the 'critical' circle - a common mistake. Circles which pass behind
this may not actually have a FoS of under 1, but are likely to have anf FoS
under the design value. Whether or not you get away with it may just be a
matter of luck (not good engineering!). The mistake became common with strong
strip reinforcement which needed long anchorage lengths to mobilise working
load - more 'anchored earth' than 'reinforced soil', and so tended not to throw
up too many problems. With modern sheet and grid materials, anchorage lengths
are rather short, and it is easy to end up with surfaces with F<1 if you use
this approach.
Paul McCombie
Department of Architecture and Civil Engineering
University of Bath
UK
Quoting Paul Bryden <[log in to unmask]>:
> Hello Chibizau,
>
> There is an article posted on our web site which describes the process
> for
> modelling soil nails using SLOPE/W Version 4. You will find Article 201
> and
> it's corresponding SLOPE/W data files available for free download at
> http://www.geo-slope.com/support/articles.asp.
>
> We will be releasing Version 5 of our GEO-SLOPE Office suite of software
> in
> October and we have made significant changes to the way that we
> implement
> structural components such as anchors, nails and geo-fabrics. For
> example,
> you will now be able to choose either a Constant or Variable
> reinforcement.
> With a constant reinforcement the working load you specify will be the
> same
> for all trial slip surfaces, together with the specified bond resistance
> per
> unit length SLOPE/W will compute the required bond length behind the
> critical slip surface.
>
> The variable reinforcement option limits the working load depending on
> the
> reinforcement length behind the slip surface. For each slip surface,
> SLOPE/W
> will first compute the available bond resistance behind the slip surface
> and
> if the total available bond resistance is greater than the working
> load
> specified, the specified working load will be applied. If the total
> available bond resistance is less than the working load specified, the
> specified working load will be reduced to the total available bond
> resistance behind the slip surface. If the slip surface is behind the
> reinforcement, the available bond resistance is zero and the working
> load
> will consequently also be zero. With this option the applied
> reinforcement
> load can potentially vary between zero and the specified working load.
> The
> applied load will never be greater than the specified working load.
>
> More information on the enhancements made to GEO-SLOPE Office are
> available
> from our web site at http://www.geo-slope.com/version5/.
>
> Warm regards,
>
> Paul Bryden
> Marketing Director
> GEO-SLOPE International Ltd.
> http://www.geo-slope.com
>
> -----Original Message-----
> From: shbm msnbsh [mailto:[log in to unmask]]
> Sent: Saturday, August 25, 2001 9:50 AM
> To: [log in to unmask]
> Subject: bond length
>
>
> Hi everyone.
> Can someone please provide on information on the bond
> length when using SLOPE W software.
> I am trying to design soilnails using this software.
> Thanking you in advance.
>
>
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