Hi,
> 2) With my experience with geology in New Mexico, I would never adopt your
> hypothesis that the profile of the top of bedrock is in any way
congruously
> related to the top of topsoil profile. But your experience with geology
in
> your location may support your hypothesis.
well I definitely agree this is a tough issue to digest, and I am
sure this will be open discussion forever. I exaggerated
my sketch only for the purpose of making point of what
I would like to see available, or know how to accomplish.
I do not claim this is necessarily true. I heard geotechnical
engineers claim geotechnical engineering is more art than
engineering. Why? Because the investigations are done
point wise and then from what was found in discrete points,
educated guesses (or sometimes they may be less educated)
are done for the entire 'halfspace' - surrounding area.
(pretty bold guess I'd say).
Everybody ever been in touch with geotechnical engineering
is aware of that fact. That's why 'art' and that's why enormous
factors of safety as compared to some other civil engineering
disciplines (say structural engineering) - you really do not know
exactly what is going on under the surface.
Just as a comparison I will take Finite Element Analysis
(FEM). When something is modeled as finite element
model, everyone doing it is aware that the smaller the
finite elements are, the greater chances are to get more
accurate analysis results. But then it is costly (time consuming)
Or, you may have large elements and quick analysis.
In geotech engineering there are codes, and they may
require min 1 borehole per 5000 ft2 to 1 boring / 25000 ft2
or there may be some other constraints to require
more borings for the same area. But then it is
costly (money and time consuming) but of course more
accurate.
To conclude, this surface approximation is done anyway
(manually) either because project manager wants to include
that in their report or a client asks for that. To emphasize again,
everybody knows that what is among points is (an educated)
guess, and there is a big note accompanying such drawing
saying "THIS IS ONLY ESTIMATED ROCK SURFACE..."
or something of that kind.
What I am asking for is to have ability to do it quickly
and easily, maybe several versions of such 'educated guesses'
if possible and then let us users, based upon our accumulated
geotechnical/geological engineering experience decide how
accurate that is, and how to present it to a client.
There are such software on the market anyhow,
but I would like to see that option in Civil3D and use
one software rather than buy another too, and in my opinion,
with underlying Civil3D engine, it may not be even that difficult.
Thanks for you input,
--
Strah @ Langan
"Steve Cannon" wrote in message
news:6E3E8148D66BD2CCAD08374DF87A54D8@in.WebX.maYIadrTaRb...
> Hi,
>
> Disclaimer: I know NOTHING about Civil3d, I am just here lurking, learning
> what I can about the product.
>
> However, with LDD you may be able to achieve your goal:
>
> 1) Make a terrain surface representing the Top of Ground elevations (a
point
> in the terrain may be at MSL, e.g. 5280)
>
> 2) Make an LDD terrain surface representing Bore hole depths (a point
would
> be a positive depth, e.g., +10).
>
> 3) Run a composite volume with a stratum for MSL vs. DEPTH, and LDD
creates
> a composite surface. This composite surface represents the difference
> between the two compared surfaces ( a point in the terrain is the
> difference, e.g. 5280 - 10 = 5270).
>
> 4) Convert the composite surface to a terrain surface and you have your
> guesstimated top of rock surface.
>
>
> I wish to make two additional points:
>
> 1) Playing with the triangulation (flipping faces) of the borehole tin may
> give you drastically different rock surfaces (based on limited coverage of
> wide-spaced boreholes). Perhaps this process is easier and more
interactive
> in Civil3d, allowing you to play with alternatives.
>
> 2) With my experience with geology in New Mexico, I would never adopt your
> hypothesis that the profile of the top of bedrock is in any way
congruously
> related to the top of topsoil profile. But your experience with geology
in
> your location may support your hypothesis.
>
> Can this be done easier or differently in CIVIL3D? Maybe others will
> contribute...
>
> sc
>
> Strahimir Antoljak wrote in message
> news:FE2978F1CF422943E2C1CB9F55D5994F@in.WebX.maYIadrTaRb...
> >
> > We are multidiscipline company
> > Civil/Geotech/Environmental/etc
> > and here is the fairly frequent
> > requirement we have with
> > regard to Rock Surface/Contours
> > (but I can envision very similar
> > application/benefit for creating
> > pollutions surface/contours or
> > anything else).
> >
> > We get existing surface data
> > from surveyors. This is always
> > detailed.
> >
> > Then our Geotech/Environmental
> > people go to the site and collect
> > boring/environmental logs. The
> > number of logs may very between
> > say 30 (more often) to 150 or more.
> >
> > In certain cases the geotech people
> > look to encounter rock and they
> > collect rock depths/elevations.
> > (The environmental people collect
> > PID values, etc).
> >
> > So we have very detailed existing
> > surface and only 30+ points to represent
> > rock depth. Often, the geotech people
> > want to see estimated/rough rock surface
> > and contours. Now, 30+ points is too
> > few points, I'd say, even for approximate
> > surface.
> >
> > Is there a way, or can it be built in the
> > future release of Civil3D, to automatically
> > (not manually) generate multiple interpolated
> > points based on 30+ known points and
> > accounting for existing surface - see attached
> > figure.
> >
> > Thanks,
> >
> > --
> > Strah @ Langan
>
>
>
>