The seismic dilatometer test sdmt in geotechnical inshore and offshore investigation
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The Seismic Dilatometer test (SDMT) in geotechnical inshore and offshore investigation PowerPoint PPT Presentation

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The Seismic Dilatometer test (SDMT) in geotechnical inshore and offshore investigation. Studio Prof Marchetti. Some examples of maritime construction. Mooring. Trench for pipe. Wind generators. Sheet piles. Oil and gas platform.

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The Seismic Dilatometer test (SDMT) in geotechnical inshore and offshore investigation

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The Seismic Dilatometer test (SDMT) in geotechnical inshore and offshore investigation

Studio Prof Marchetti

Some examples of maritime construction


Trench for pipe

Wind generators

Sheet piles

Oil and gas platform

Common tests in offshore investigation

Close water (harbours and bays)

- inshore tests

Open water (sea)

- offshore tests

Shallow water < 30 m

Deep water > 30 m

  • Short test (5 m)

  • cables

  • - pipes

Short test (5 m)

Deep test (30 m)

- foundations

Deep test (30 m)

La Spezia (Italy)Shipyard Beconcini




Harbour: DMT test from pier


  • Make a hole in the deck;

  • Set up the guidepipe;

  • Fix the penetrometer and do the test;

Beam braching

Harbour: DMT test from provisional pier

Salerno harbour (Italy)

Trapezio Deck

DMT test with Floating Wheels Module

Two ton static penetrometer mounted on a floating raft, with screws for anchoring.

Only for very shallow water: 1-2 m;

Short test: 5 m

DMT with SPT hammer for shallow water: Costa Rica

DMT test with Torpedo - layout





Vado Ligure, ItalyNew embankement area

Venice lagoon, Italy (MO.SE.)

DMT test from Jack-up

SDMT tests from a floating barge

SDMT test from a floating barge: layout

Test execution

Barge is free to float.

The upper end of the telescopic pipe is fixed on the pontoon, the lower end is on the seabed. It is a guide for the dilatometer rods.

The operator pushes the rods carefully during floatation.

When the prefixed depth is reached, the operator stops the pushing system, disconnects rods and starts to take the DMT readings.

All the reading are taken when the DMT is fixed, not during penetration.

SDMT from a floating barge: Genova (Italy)

New Terminal Container – Calata Bettolo (Genova Horbour)

DMT from a pontoon: pushing phase

DMT from a pontoon: reading phase

10 days rental ≈ 10.000 €

Jackup vs Floating Barge: cost comparison

10 days rental ≈ 300.000 €

In 10 days you save 290.000 €

DMT from floatinf barge and jackup: Barcelona (ES)

Enlargment Barcelona harbour – collapse of the pier

DMT test with torpedo in deep water: layout

Expensive heave compensated ship for offshore test

DMT test for seabed < 100 m of depth;

Test depth: 30-40 m;

Seafloor DMT for shallow water


Test depth: 5-7 m

Seafloor DMT in deep water

Ok usingany vessel with at least 2 ton crane

Test depth: 5-7 m


Max seabed depth: 100m

(due to DMT cable)

What about DMT tests at depth > 100 m ?

No pneumatic cable between vessel and DMT


Medusa Project

Elettronic Board

Pressure Transducer

Pressure Generator

Designed for seabed up to 2000m

Summary and Conclusions

  • Same blade for offshore and onshore sites

  • No calibration necessary for the (high) pore pressure

  • DMT test is independent from the method and speed of penetration (same high quality data using many different penetration methods)

  • Test is rapid and economical if performed with a penetrometer on a floating barge

  • Today SDMT tests are possible up to 100m (using expensive vessels)

In the near future..

  • The seafloor DMT will allow to perform shallow tests (5-7 m depth) with a seabed up to 100 m. The test will be very economical because it may be performed using a common vessel with a little crane (2 ton)

  • The Medusa DMT will allow to perform DMT tests up to the depth of 2000 m

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