CPTU - "the sound of Music for the Geotechnical Engineer"
a few case stories from the field:

In Iasi, Romania, Eliprom Systems are using the CPTU for chcking the soil before and
after soil improvement.

In HoChiMinh City, Vietnam, ANH VU Geotechnical and Civil Engineering Co.Ltd
( former Portcoast Consultant ) are operating two of our CPTU units since 2006.
This result and pictures are taken from the geotechnical investigation for a new
Highway outside the city. The results show a typical normally consolidated clay
down to 35 meters with sand layers at 30 meters of depth.

In SUDAN, the ESD Geotechnical and Engineering Co. performed a geotechnical survey
for a new Refinery in Port Sudan at the Red Sea coast.
When constructing the pier, some of the bottom material had to be dredged away and
the investigation had to show the extent of the dredging.

A result from CPTU performed at a water depth of 6 meters from a Jack-up Barge.
The sounding starts 1 meter down from the actual sea bed.
1 – 2.3 meters is very soft material and 2.3 to 3 meters, the cone has penetrated a coral reef. At 3 to 5.5 again the soft material and eventually the limestone begins getting successively harder.
It is clear that any building structure must be placed at the hard material at 6 meters and the coral reef must be removed.

Pore pressure Point resistance Friction Friction ratio Soil type

The CPT is an excellent tool for checking soil improvment.
The German company KELLER GRUNDBAU are constantly using the Memocone system
to check the level of soil improvement before and after deep vibration.

LaÁlaÁl, Kuwait, SALT FLAT CITY, on-going project.

SALT FLAT CITY. ( Extracted from Ground Engineering May 2004.)

Land reclamation works have begun to create a "sea city" on the Arabian Gulf at Al Kihiran in southern Kuwait.
It is called Pearl City and is being developed by La'Ala'Al Kuwait Real Estate Company with Buro Happold providing civil and ground engineering design services.
Deep Dynamic Compaction ( DDC ) is used for the reinforcement of the soil and CPTU is the main method for the validation. Sufficient improvement was defined by achieving an average minimum point resistance ( qc) of 7.5 MPa. The friction and pore pressure measurements were mainly used to identify unwanted material such as peat or clay.

Investigate all the canals of Venice with only 3 channels

S.P.G. (Sachetto Perforazione Geotecnia) from Adria in the north of Italy have made a series of CPTu tests in the narrow canals of Venice. They used a modular barge of their own design called MOD-GEO. The MOD-GEO has been made in order to have a small, self-lifting 100kN static penetrometer equipped with ENVI Memocone cpt probe to use in the narrow canals of Venice (called Rii).

In these last years many projects have been promoted about the canal dredging (since they are full of silty mud) and the project of the so called INSULAE ("Islands"). The project of Insulae consists of making some local projects of recovering some defined areas or sites of Venice called Insulae. At every site, the project includes an incorporated wall to protect the Insula from high tide. All the canals must be carefully cleaned from mud before each project. Many Geotechnical tests must be carried out in order to achieve some reliable data to understand what happens when the water is pumped out from the canals and all the old foundations are dried out.

The most reliable, quick and therefore inexpensive test in soft soils like in Venice is found to be CPTu.
MOD-GEO is equipped with four retractable "legs" with platforms. The legs are lifted by hydraulic systems which also operates the penetrometer. When the MOD-GEO is lifted from the water its weight is approximately 3,5 tons, which is enough to make tests down to 20 m in Venice. If more weight is needed, two tanks can be filled with water.

The piezocone used is the Memocone II from ENVI. The high sensitivity of the 50 MPa probe (2kPa) was very useful in the
extremely soft mud layers. This made it possible to detect the level of the required dredging of the canals of Venice.

Massimo Sacchetto
SPG
Adria, Italy

CPTU with RESISTIVITY.

Quick clay.
It is possible to use Memocone with a resistivity module attached in order to indicate the presence of quick clay. The quick clay having a lower salt content than normal clay.
A number of tests over an area can produce a resistivity profile.

Environmental survey.
Some pollutions in the soil will change the resistivity and can tus be screened
by using this module.