AGSi Guidance / Model¶
Models showing exploratory holes¶
It is common for models to incorporate representations of exploratory holes and their geological interpretation, typically displayed as cylinders with different segments coloured to represent different geology. These representations may be considered to be 'supporting data' to the model itself. One of the benefits is it provides a visual indication of the data used to generate the model.
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The section discusses how exploratory holes can be handled within AGSi.
The term hole is used in this section in the interests of brevity to represent any type of exploratory hole including boreholes, coreholes, pits, CPT etc.
Modelling exploratory holes - principles¶
AGSi allows the holes to be modelled separately from their geology. These hole objects can be used to indicate the location and extent of the hole as well as hole metadata. How this information is represented in the model will be determined by the software being used for viewing. Modelling the holes themselves in this way is optional in AGSi as the representation of the geology (discussed below) does not rely on it. Users (modellers and specifiers) should determine whether holes are to be represented using this method.
Holes may be grouped in to sets of exploratory holes. The division of holes between sets may be determined by the user. Examples include different sets for holes from different investigations, or for different types of hole. Alternatively there may be no division, in which case all holes belong to the same set. Sets are important for the implementation of the schema as a single model element will reference one set of data (described below).
Note
It is possible for each hole to have its own set and there may be situations where this appropriate. However, it is not recommended for the general case.
To model the geology found within holes, the hole is divided up in to segments which are each assigned some geological (or similar) information. This will commonly include a classification, e.g. geological unit, and possibly a description.
The segments may also be grouped in to sets, with a single model element referencing one set. Most commonly the sets will be aligned to the geological classification. However, if the holes have been divided up into sets then it the sets will typically align with the combination of geological classification and hole.
It will commonly be the case that the geological classification and description will be the same as found in the factual data, i.e. same as on the borehole log. However, this does not need to be the case. For example, the modeller may prefer to include simplified (interpreted) descriptions where full descriptions are long and detailed.
It is possible for individual test results to be reported. This may be done by creating and referencing agsiDataPropertySet objects, generally from the hole object. An example showing how SPT results may be reported is described below.
Note
AGSi is not intended to replace or replicate the AGS format for transfer of factual data. By default, the objects discussed here are only intended to carry limited information, most likely a summary of significant data selected by the creator of the model.
Modelling exploratory holes - use of schema¶
The exploratory hole representations are considered to be part of a model. A model is established by defining an agsiModel object, which will contain general metadata for the model.
If the overall model incorporates, for example, a 3D volume model, then separate agsiModelSubset objects may be defined for the 3D volume model and the exploratory holes. The agsiModelSubset objects are embedded within the applicable agsiModel object under the corresponding attribute.
Note
Use of subsets is not an AGSi requirement. Users and specifiers should determine whether subsets are to be used.
A number of model elements are then defined using agsiModelElement objects.
For the exploratory holes themselves, each model element will comprise a set of holes defined using the agsiGeometryExpHoleSet object. The use of sets is further described above.
Each individual hole is described using an agsiGeometryExpHole object. This includes the geometrical data for the hole as well as some limited metadata. If further data is required to be associated with the hole then this may be achieved populating an agsiDataPropertySet object and referencing it via the propertySetID attribute.
For each set of holes, the relevant agsiGeometryExpHole objects are embedded, as an array, within the agsiGeometryExpHole attribute of the corresponding agsiGeometryExpHoleSet object.
For the segments the process is identical to the above but with each set of segments defined using an agsiGeometryColumnSet object and the individual columns described using agsiGeometryColumn objects, with the latter embedded within the former as an array using agsiGeometryColumn attribute.
A simple example illustrating these concepts is given on the next page.