Geotechnical
map is commonly used to support projects, especially civil engineering projects
and land use planning. It can provide engineers with information regarding soil
types and their bearing capacity. Therefore, geotechnical map helps to figure
out the best location for specific building and the best type of foundation to
be used in order to avoid problems that can be caused by soil such as swelling,
excessive settlement, landsliding, etc.
In
this paper Geographic Information System (GIS) was employed to construct a
knowledge base for geotechnical experts. The procedure based on employing the
ArcGIS software and its extensions: Geo-statistical and Spatial Analyst in
applying interpolation methods and representing results. Soil data for more
than 100 boreholes logs distributed within city of Nablus were manipulated
through ArcGIS software to test its capability for spatially modeling its types
all over the city.
The
interpolation procedures were implemented to display the soil type information
for any point of the whole area. Kriging, Inverse Distance Weighting
(IDW) and Thiessen polygon interpolation procedures were used to
predict soil type’s distribution. The qualitative description of the soil was
turned into quantitative figures that could be interpolated by means of coding.
The results of the study showed non realistic distribution for soil types at
some places when using IDW and kriging methods, the minimum average error in
predicated soil type was achieved when using the Thiessen polygon method.
It can be
concluded that GIS techniques through ArcGIS and its extensions could be
considered as a good base for developing an expert system for geotechnical
investigation for soil types.