Marchetti Flat Dilatometer Test (DMT)

Marchetti’s Flat Dilatometer Test (DMT) consists of a steel membrane that is pneumatically expanded against the soil at 0.2-m intervals. During this process, pressure readings are recorded and used to obtain information on soil stiffness and stress history. The pressure readings can be correlated to geotechnical parameters such as:

  • Overconsolidation ratio;

  • Constrained modulus;

  • Undrained shear strength;

  • Soil behaviour type; and

  • Friction angle.

The DMT complements other in-situ geotechnical technologies such as CPT and SCPTu. Compared to these tools, the DMT is particularly sensitive to horizontal stress due to the blade shaped probe.

Furthermore, given the DMT blade robustness, it can be advanced into the ground using static push or hammering. The DMT is applicable in a wide range of geological settings, from ‘semiliquid’ to hard soils.

Samples can be rapidly collected using direct push technology in adjacent locations upon request.

MAJOR BENEFITS OF DMT

  • Standardised operation. Repeatable and reproducible.

  • Higher sensitivity to horizontal stress than other in-situ tests.

  • Faster collection of data at greater resolution than conventional methods such as SPT and sampling.

  • Real-time data collection.

  • Quick dissipation tests able to identify ‘niche’ silts.

  • Dynamic push (hammering) can be used to advance the tool into the ground.

SOME DMT APPLICATIONS

  • Compaction control.

  • Settlement prediction.

  • Liquefaction evaluation.

  • Detecting slip surfaces in clay slopes​.

  • Laterally loaded piles​.

  • Estimation of permeability in clay.

  • Estimation of subgrade modulus for pavements and diaphragm walls.

  • Soil stress history investigation.

FURTHER INFORMATION

Our field technicians will be happy to provide further information and discuss in detail any specific project requirements.

In the meantime, we recommend you consult the following documents: