Many of the large cities in the world are located in coastal plains or deltaic areas, near rivers and other waterways. Although these locations may be favorable from an economic point of view, they are often dominated by poor subsoil conditions. Highly compressible fine grained sediments such as clays, silts and peat, generally have low shear strengths and cause settlement and stability problems when loaded by structures like roads, railways, dikes, fills, etc. Economic incentives nowadays stimulate trends like the reduction of the return-on-investment period and, therefore, the construction time, but encourage also seemingly conflicting construction requirements reducing the maintenance during the operational lifetime of the structures. In addition, growing public awareness in a more and more congested environment urges the construction risks to be reduced. These developments combined with shifting responsibilities as a result of new contract forms (i.e. turn key, etc.) have stimulated the development of new techniques to either accelerate the consolidation process or reduce the absolute settlements in compressible soils without running into risks of failures or long-term maintenance. Systems to accelerate the consolidation process are all based on 2 principles: " Reduction of the length of the drainage path of the pore water and/or the application of a surcharge. A surcharge usually consists of sand, but may also be the atmospheric pressure as result of vacuum consolidation. " Reduction or elimination of settlements is generally achieved by either reducing the compressibility of the cohesive strata by introducing binding agents in the ground (block stabilization) or concentrating the bearing loads onto stiff elements like piles or columns that transfer these loads to underlying, more compete nt strata. Some techniques combine the acceleration of the consolidation with the use of stiff elements. Generally the techniques that reduce or eliminate settlements will be expensive in comparison to those that accelerate consolidation. This paper will focus on a new system called BeauDrain that combines the proven technique of vertical and horizontal drainage and vacuum consolidation with an innovative installation procedure. The soil mechanical principles, the system itself, the design and monitoring and the results of a test site, known as the test site Zevenhuizen, will be discussed. Finally the performance of the system during the construction of the RW 11, a highway between Alphen a/d Rijn and Bodegraven in the Netherlands, will be reviewed by presenting and interpreting monitoring data. For the covering abstract see ITRD E135448.
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