Publication Abstract

Proceeding of the 2018 DFI-EFFC International Conference on Deep Foundations and Ground Improvement, Rome, Italy, (DFI, EFFC)

Mega Soil Improvement Case Study: Improvement of Soft Soil Using Prefabricated Vertical Drains
Robert Thurner, Technical Director ME and Mohamed Ayeldeen, Senior Engineer

A huge industrial area in Egypt of more than 60 km2 was found to contain very soft clays up to 50 m depth. The ideal solution to achieve the required goals for the soil improvement is to install some hundred million meters of prefabricated vertical drains (PVD) in combination with a surcharge of a height of 6.5 m. One of the biggest challenge was to build up a simple design model throughout this huge area with wide variation in the soil properties/conditions. Next to the locally available experience regarding the soil conditions and the primary soil investigation, a quite intensive soil investigation campaign with more than 150 CPTUs and 600 dissipation tests was going on parallel to the installation to adapt the preliminary design. It was essential to build a trial field including several types of instrumentations for intensive monitoring of the occurred deformation. The collected data was used to predict the soil behavior and the development of the settlement. Simple to sophisticated calculation models have been used to evaluate the effectiveness of the works that were executed. Some standard methods such as Sherif and Asaoka were applied using the settlement measurements, while for the trial field, a combined evaluation and check of the concepts applied has been done using multiple-level piezometers, inclinometers, extensometers and other instrumentation. This has been combined with 3DFEM analyses to understand the behavior of the entire system and to optimize the soil improvement scheme. In the proposed paper an overview and some interesting details will be given about the multiple tasks during the design, evaluation of the trial field and execution of the geotechnical works. Some equations and models have been developed and verified with the measured parameters.

 article #3053; publication #1040 (ROME-2018)