Inferring the Creep Settlement Behavior of Rockfill in Reclaimed Lands by Advanced SAR Interferometry and Numerical Modeling: An Example from Arabian Gulf

Michele Di Lisa,Hossam Eldin A Ali,Serena Moretto,Paolo Mazzanti

doi:10.3390/rs12030527

Abstract

Satellite Advanced Differential Synthetic Aperture Radar Interferometry (A-DInSAR) is becaming a key-technique for monitoring ground deformations. The potential of A-DInSAR for settlement monitoring is exploited in this paper through the investigation of a reclaimed land in Dubai (UAE). Time histories of displacements were obtained from COSMO-SkyMed satellite images over the period between 2011 to 2016, allowing to derive the long-term deformation of the entire artificial island. Special attention was paid on long-term settlement of the hydraulically-placed rockfill of the peripheral rubble-mound revetments. The A-DInSAR results have been compared with results derived from numerical analyses and with field surveys, proving the relation between observed and modeled displacements. The study has also revealed that rockfill long-term settlement (creep) rate is significantly dependent on the aging (time since placement). In the analyzed time-frame (2011–2016) it has been observed that recently placed rockfill experienced creep rate up to ten times higher than the creep rate measured for similar rockfill structures placed 30 years earlier. Furthermore, it has been demonstrated that static compression by preloading and dynamic or impact densification induced by wave forces proved to have also a significant impact on reducing the creep rate of the rockfill.

Highlights

Land reclamation is a common practice in all Gulf Countries, including the coastal area of Dubai (UAE)
The results focus on the creep settlement computed after the removal of the preloading surcharge load
The A-DInSAR results were compared with geotechnical modeling, in order to validate the creep settlements affecting the rockfill part of the artificial island

Summary

Introduction

Land reclamation is a common practice in all Gulf Countries, including the coastal area of Dubai (UAE). It generally includes filling with marine carbonate sand for the main reclamation land body and hydraulically-placed rockfill for seawalls containing the reclamation fill [1,2]. Long-term settlement in reclaimed lands is a critical task to be assessed; it depends primarily on the properties of the fill materials and, secondarily, on additional external factors (i.e., aging, placement methods, compaction techniques, wave forces, and temperature variation) [3]. The focus of this paper is the long-term settlement of rockfills, which is usually neglected or underestimated, it can cause large deformations of this material [5,6]. The most severe impact of this settlement is pronounced when buildings are founded above or behind such rock structures

Methods

Results

Conclusion