Initial software developments on Z_Soil^®. PC started at Zace Services Ltd, Lausanne, Switzerland in 1982, under the supervision of Thomas Zimmermann, with a team  composed of Carlos Rodriguez, Basile Dendrou, Blaise Rebora, and Françoise Delaraye, with research experience at the Swiss Federal Institute of Technology in Lausanne, U.C.Berkeley, Caltech, and Purdue University.

The original PC version, including essentially single phase media, appeared in 1985 and rapidly raised interest.

Later on, M. Howe(Univ. of Cape Town & Univ. of Texas Austin), J.Diaz( ETS Geneva & EPF Lausanne), E. Seker(Tech.Univ.Istanbul & EPF Lausanne) , E. Davalle (EPF Lausanne & UC Berkeley), A.Truty (Tech.Univ.Cracow) successively joined the development team and contributed to version 2, which appeared in 1990 and already included fully coupled two-phase media. Simultaneously dedicated versions with special capabilities were developed for several major companies.

The early nineties were marked by the start of a 10 years interaction with the Swiss Federal Institute of Technology in Lausanne and several local engineering firms. This collaboration aimed at developing a fully 3D version of Z_Soil^®. PC. Several laboratories of the Swiss Federal Institute of Technology in Lausanne made some contributions to this effort: the Laboratory of Structural and Continuum Mechanics (Prof. F. Frey), the Laboratory of Rock Mechanics (Prof. F. Descoeudres), and the Laboratory of Soil Mechanics (Prof. L. Vulliet). Several new people also joined Zace’s development team: A. Urbanski (Cracow Univ. of Technol.), K. Podles (Cracow Univ. of Technol.), B. Rutscho (ETS Bienne), D. Alvarez (Univ. of Catalunya), A. Wroblewski (Cracow Univ. of Technol.), W. Atamaz Sibai (Univ. of Damas, Univ. of Swansea UK, EPF Lausanne) and later A.Wiktor (Cracow Univ. of Technol.). Several engineering companies supported the development with scientific contributions, validations and financial support : Bonnard & Gardel ingénieurs conseils SA, Lausanne, GEOS ingénieurs conseils SA, Genève, GVH ingénieurs conseils SA, Tramelan, INTRON, Yverdon, KBM, Sion, Schneller-Ritz und Partner AG Ingenieurbüro, Brigue,   Stucky ingénieurs conseils SA, Lausanne, and later Emch + Berger Ing. AG, Berne. Collaborations with P.Roelfstra (Delft Univ. of Technol., EPF Lausanne), Ph. Menétrey (EPF Lausanne, Univ. of Colorado, Boulder) and J.-L. Sarf (EPF Lausanne), in particular, led to significant progress in specific chapters.

First available only to development partners, Z_Soil^®. PC 3D is since 2002 available to all interested companies.

2005 marked the 20^th anniversary of Z_Soil^®. PC, this gave the opportunity to distinguish outstanding contributions with the first Z_Soil awards:

Marina Pelevina of Moscow State University of Civil Engineering received the 2005 Z_SOIL FRESHMAN PRIZE.

Nowadays, Z_Soil^®. PC is present on five continents and used daily in academia and in engineering practice, on small stability calculations as well as on multi-million engineering projects like the Loetschberg tunnel across the Alps, the extension of the Lausanne subway network, and also on dams, tunnels, roadworks, bridges, deep excavations, buildings etc.

Many such projects are documented in publications downloadable from www.zace.com. Worldwide consulting services are available from Zace Services Ltd and partners; training courses are organized monthly and some are available online.

Version 2007 will appear in April 2007. This latest development will introduce a simplified interface, new meshing capabilities, improved performance, new constitutive models, large displacements, pushover and dynamic capabilities .

            Today, Z_Soil^® developments are coordinated by:

Thomas Zimmermann, professor of structural and continuum mechanics at the Swiss Federal Institute of Technology, Lausanne and CEO, Zace Services Ltd., and

Andrzej Truty, professor of geomechanics at Cracow University of Technology, Poland, and Chief developer at  Zace Services Ltd.

            Acknowledgements:

Financial support of the Swiss Commission for Technology and Innovation (CTI) under grants 2672.1, 2387.1 and 2995.1, for version 4, and grant 4182.1, for version 6, is acknowledged. Advice on finite element methodologies provided by T.J.R.Hughes (TICAM, Austin) since the early days has often been crucial, his advices are gratefully acknowledged. The many inspiring discussions with J.P.Wolf (EPFL) throughout the years and with J-H.Prevost (Princeton Univ.) at the early stage of the project are also acknowledged.