Geotechnical investigations are performed to obtain information on the properties of soil and rock around a site. A geotechnical investigation involves a desktop search of known mapping data and site characteristics and on-site borehole drilling for acquisition and classification of samples. The data gathered during the geotechnical investigation is used to design earthworks, retaining structures and foundations for proposed structures. The investigation data is also used to perform geotechnical risk assessments and earthworks estimating.
Site inspection and testing
Soil and rock identification
In-situ and laboratory
Invesitgation and assessment
Gabion | Cantilever | Piles
Estimation and Design
Site classifications are requested by councils and developers to determine the suitability of a site for construction and the optimal foundation type. Site classification reports are completed in accordance with AS 2870-2011 Residential slabs and footings. The site classification report consists of three parts, a
Soil and Rock Classification
Soils are classified according to their engineering properties for use as foundation support or building material. Soil is classified into three major classification groups:
- Coarse-grained soils (e.g. sands and gravels)
- Fine-grained soils (e.g. silts and clays)
- Highly organic soils (referred to as "peat")
To learn more about soil and rock classification click here.
Geotechnical Soil Testing
Geotechnical testing involves collecting soil samples in either a "disturbed" or "undisturbed” state. A disturbed sample (e.g. from an auger) will allow classification of grain size, water content and colour but it’s properties will not represent the true in-situ soil properties. Undisturbed samples aim to maintain the in-situ soil state, allowing the soil properties (such as the bearing capacity) to be tested. Broadcrest uses undisturbed thin wall tube sampling to ensure the highest quality soil testing.
Landslide Risk Assessment
Slope instability occurs in many parts of urban and rural Australia and often impacts on housing, roads, railways and other development. Local and state government authorities have recognised this and begun requiring stability assessments prior to allowing building development. Broadcrest’s landslide risk assessments are performed in accordance with local council requirements and the Australian Geomechanical Societies’ Landslide Risk Management (2007).
Retaining walls are designed to bind soils between two different elevations. Retaining walls are used in areas with undesirable slopes or where the landscape needs to be shaped more specific purposes like hillside farming or roadway overpasses. There are a variety of types of retaining walls, including gravity, cantilever, sheet piling, bored piles and anchored walls.
Learn more about the different types of retaining walls and how to choose the right retaining wall for your project here. Basement construction which requires temporary support/propping is discussed here.
Cut and fill
Bulk earthworks use cut and fill to minimise the amount of construction labor, time and cost involved in earth moving. A cut and fill investigation is used to develop a 3D model showing the bulk volumes, levels, layout and planning dimensions.
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