Overview

The dilatometer test (DMT), sometimes referred to as the flat dilatometer test, is carried out by pushing a flat plate with a membrane into the ground using a CPT rig. At set depths, the push is stopped, and the membrane inflated against the soil using gas pressure. The resulting measured pressures provide information about the soil’s geotechnical properties. A downhole seismic module can be attached to the DMT blade to undertake seismic dilatometer testing (SDMT).

As the test measures pressures over a known displacement, modulus values are obtained directly. These are correlated to values of Young’s Modulus, E and constrained modulus, M. The test is therefore ideal for settlement and deformation problems. The test is performed in the horizontal direction and so is also excellent for determining at rest horizontal stress ratio, Ko, and for lateral loading problems.

Ground Investigation Ltd introduced this equipment to New Zealand in 2009 and was the first contractor in New Zealand to provide this test. As such, we have over ten years’ experience with this equipment having done thousands of individual DMT tests throughout New Zealand.

We undertake the DMT work in accordance with the international standard, ASTM D6635-01.

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Related Projects

Building Seismic Upgrades | Ghuznee Street, Wellington

We have carried out many investigations using our hand portable pushing equipment under canopies next buildings and inside the confines of existing buildings for seismic upgrade projects. Both SDMT and CPT testing can be undertaken using this equipment.

Wharf and Port Development | Sulphur Point Wharf, Tauranga

We have carried out CPT and SDMT tests for various wharf and port developments, including; Sulphur Point Wharf, Tauranga, Lyttelton Port and Ports of Auckland.

Ground Improvement Projects | Old Taitapu Road, Christchurch

We have carried out CPT and SDMT tests using both our Pagani and Truck CPT rigs on numerous ground improvement projects throughout New Zealand, but mostly in the Christchurch area following the Canterbury earthquake sequence. We have tested for ground improvement methods of deep soil mixing, stone columns, driven piles and mass stabilisation projects.