Geomechanics and Engineering

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Evaluation of performance of piled-raft foundations on soft clay: A case study

  • Khanmohammadi, Mohammadreza (Department of Civil and Environmental Engineering, Amirkabir University of Technology) ;
  • Fakharian, Kazem (Department of Civil and Environmental Engineering, Amirkabir University of Technology)
  • Received : 2016.12.01
  • Accepted : 2017.06.22
  • Published : 2018.01.20
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Abstract

Applicability of constructing piled raft foundations on soft clay has been given attention in recent years. Lack of sufficient stiffness for soil and thus excessive settlements to allow higher contribution of piles is the major concern in this regard. This paper presents a numerical investigation of performance of piled-raft foundations on soft clay with focusing on a case study. A 3D FEM numerical model is developed using ABAQUS. The model was calibrated by comparing physical and numerical modeling results of other researchers. Then the possibility of using piled-raft system in construction of foundation for a water storage tank in Sarbandar, Iran is assessed. Soil strength parameters in the numerical model were calibrated using the instrumentation data of a heavily instrumented preloading project at the construction site. The results indicate that choosing the proper combination of length and spacing for piles can lead to acceptable differential and total settlements while a high percentage of total bearing capacity of piles can be mobilized, which is an efficient solution for the project. Overall, the construction of piled-rafts on soft clays is promising as long as the total settlement of the structure is not imposing restrictions such as the common 25 mm allowable settlement. But instead, if higher allowable settlements are adopted, for example in the case of rigid steel tanks, the method shall be applicable with considerable cost savings.

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References

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