Field book



Geotechnical engineering in French Guiana.

In late May 2011, as part of the implementation of a new road bridge on the Cayenne river in French Guiana, the company Jean Lutz SA has assisted the company SAFOR Guiana in charge of the work of geotechnical engineering on behalf of the DEAL (Directorate of Environment, Land and Housing - Guiana).  

The existing bridge, called Larivot Bridge, was designed between 1974 and 1976. It acts as a connection between the city of Cayenne (with Rochambeau airport and the port of freight of Degrad des Cannes) and western Guiana (with for example the Guiana Space Centre in Kourou). 



One pile of this bridge has been damaged in 2009, causing heavy work in late 2009 and early 2010. These repairs has forced the users to bypass for more than 40 kms through roads which were not suited to this type of traffic.  

Following this work and given the strategic importance of this road (road transport, drinking water supply, electricity supply and optic fiber), the DEAL has decided to double the bridge. In this sense a geotechnical study should be done with some penetrometric tests, core samples studies and pressuremeter tests. 



The company SAFOR Guiana was commissioned to carry out the drilling and testing on both shores of the river.  

The company owns two drilling recorders (BAP160) and one pressuremeter instrumentation (PREVO) for making pressuremeter tests. 




The softwares (EXGTE, EXPRS) and the instrumentation of Jean Lutz SA have allowed the qualified personnel of the company SAFOR Guiana to overcome the site specific constraints (sticky gray clay on 35m of ground, close to the mangrove, weather - rainy season...) and to provide to the DEAL all the required studies.

Following these tests on shore, geotechnical surveys will be conducted on a barge before the end of the year (a campaign about a month, including four pressuremeter surveys and 4 core drilling down to 5 m into the sound rock ).