We were called to a site near Koombana Bay for a six-storey commercial building where the geotechnical model from SPT alone left too many unknowns for the pile design. The sand layers there are interbedded with stiff clay lenses, and the SPT N-values bounced around so much that the structural engineer could not lock in a reliable shaft capacity. Running a Ménard pressuremeter test (PMT) in those boreholes changed everything. Instead of relying on empirical correlations from a blow count, we obtained direct stress-strain curves at the depths that mattered. The PMT gave us the limit pressure and the Ménard modulus, which fed straight into the pile settlement calculations. For projects where the soil profile is variable, especially in coastal Bunbury, the PMT provides the kind of load-deformation data that a cimentación superficial analysis alone cannot deliver.
The PMT's direct measurement of horizontal stress and modulus is unmatched for designing foundations in Bunbury's interbedded sand and clay profiles.
Methodology and scope
Local considerations
Bunbury's population has grown past 75,000, and with it the number of multi-storey developments on marginal land near the Leschenault Estuary. The risk of differential settlement in these soft estuarine deposits is real — we have seen cases where a building designed with SPT-only parameters settled 40 mm more than predicted. The Ménard pressuremeter test (PMT) reduces that uncertainty by measuring the soil's stiffness in situ, under controlled loading. When you are pouring concrete for a raft slab or a pile cap, a 20 mm difference in settlement can mean cracked partitions and stuck elevator doors. The PMT gives the design team a defensible modulus value, not a guess from a chart. For sites underlain by the Yoganup Formation, where cemented layers can mask the behaviour of the underlying soft clay, the PMT is the only practical way to capture that contrast.
Applicable standards
AS 1726:2017 Geotechnical site investigations, AS 4678:2002 Earth-retaining structures (lateral pressure application), AS 1289 Standard test methods for prebored pressuremeter testing in soils
Associated technical services
Pre-bored PMT in cased boreholes
We install the Menard probe in pre-bored, cased holes to prevent collapse in loose sands or soft clays. This method gives reliable data for deep foundations and retaining walls.
Self-boring PMT (SBPMT)
For undisturbed measurements in sensitive clays, we use the self-boring version that advances with minimal soil disturbance. Ideal for the soft estuarine deposits around Bunbury's waterfront.
Data interpretation and design report
Our deliverables include EM, pl, pf profiles, plus settlement and bearing capacity calculations referenced to AS 1726. We provide graphs and tabulated results for your structural engineer.
Typical parameters
Frequently asked questions
What is the difference between a PMT and an SPT for Bunbury soils?
The SPT measures blow counts in a borehole, which is an index of resistance, but it does not give a direct stress-strain curve. The PMT inflates a flexible membrane against the borehole wall and measures the soil's actual deformation under controlled pressure. For Bunbury's interbedded sands and clays, the PMT provides a modulus value that can be used directly in settlement analysis, while the SPT only gives a correlation. Both tests complement each other, but for final foundation design, the PMT reduces the uncertainty in the settlement prediction.
How much does a Ménard pressuremeter test cost in Bunbury?
A standard pre-bored PMT at one depth in a single borehole, including mobilization within the Bunbury area and a basic interpretation report, typically ranges between AU$1,750 and AU$2,230. The final cost depends on the number of test depths, the total borehole length, and any additional laboratory testing required. We provide a fixed-price quote after reviewing the site conditions and the scope of work.
At what depths can you run a PMT in Bunbury?
We can test from about 1 metre below ground surface down to 30 metres using standard drill rods. The maximum depth is limited by the drilling rig's capacity and the stability of the borehole. In the loose sands near the coast, we often case the hole to prevent collapse before inserting the probe. For deeper testing, we can extend the rods, but the practical limit for most Bunbury projects is around 25 metres, which covers the typical foundation depth for multi-storey buildings.
What parameters do I get from a PMT for my design?
You get three primary parameters: the Ménard modulus (EM), which is the soil's stiffness under horizontal loading; the creep pressure (pf), which indicates the start of plastic deformation; and the limit pressure (pl), which is the ultimate resistance before failure. From these we calculate the bearing capacity for shallow foundations, the settlement under working loads, and the lateral resistance for piles. For Bunbury's variable soil profiles, the EM profile is particularly useful for differentiating between stiff clay lenses and loose sand layers.