CPT testing in Vietnam using Memocone III

PORTCOAST CONSULTANT, Ho Chi Min City, are now using the Envi Memocone III CPTU system together with the Envi 200 kN pusher. With this lightweight unit they are able to penetrate deep and obtain CPTU results in the highest class of accuracy.

The Memocone III includes the convenience of having both real- time readings at the surface and memory data back-up memory in the cone.

CPTu 35 meters.The above plot shows cone memory data to the left and the acoustical real time data, as seen on the display of the data logger during the penetration, to the right.

In addition, a soil profile interpretation ( Eslami-Fellenius 97) is presented at the extreme right. EF97 uses effective cone resistance (qt - u2) against friction, and gives a better interpretation in this type of soil than for ex. Robertson 86.

The cone memory data is the correct one at all times and should be used for interpretation. The acoustic data is sometimes subject to disturbance in the sound wave transmission, (mostly when changing rods) and should only be used for checking the penetration and also for checking decaying pore pressure when doing dissipation tests. It is of course also very useful to be able to check the inclination in real time.
The diagrams are from left to right:

u/memory
qc/memory
fs/memory
inclination/memory
u/acoustic
qc/acoustic
fs/acoustic
fr calculated
Soil profile showing 1 = sensitive and collapsible silt down to 25 m and 2 = clay and/or silt down to 35 m.

Note: The plot is made using the new freeware "Opensounding ". For more information, please go to NEWS.

High Productivity unit 2 in Kuwait

La'Ala'Al Kuwait, have added another effective PAGANI 20 ton CPT machine and Envi Memocone CPT probe / C -mon rugged data logger to their field department. An Envi- Memovane completes the insitu ability.

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.

The PAGANI CPT machine is a belt driven vehicle and is well suited for operation on the marshland.
It is equipped with an automatic anchoring system that speeds up the anchoring procedure. The machine is also equipped with a rotary unit for augering.

CPT, Cone Penetration Test from a barge

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