Mechanical properties of stabilized dredged sediments : for sustainable geotechnical structures

Abstract: Dredging activities at Ports and Harbors are inevitable for the safe navigation of ships and vessels. Dredged material may range from very fine and contaminated sediments to sand and gravels. While, granular dredged material can be directly utilized in civil engineering applications, fine sediments may require further treatment before use. In geotechnical context, fine sediments are characterized by low shear strength and high compressibility. However, these unfavorable properties do not rule out the suitability of these fine dredged sediments for use in geotechnical construction, such as, road embankment, building foundation or as structural backfill in land reclamation. Mass stabilization solidification provides a comprehensive technology for amending fine sediments at high initial water content, resulting into construction materials of improved strength and reduced compressibility. The ultimate in-situ soil behavior types, stiffness and strength properties of stabilized mass depend on various factors such as binders, mixing equipment, curing temperature, in-situ boundary conditions and mostly important the applied preloading weight during the period of curing. However, despite improved mechanical properties for geotechnical applications, the performance of treated materials becomes susceptible to repeated freeze-thaw cycles. Understanding geotechnical design process, which includes evaluation of material properties, loading condition and selection of appropriate constitutive model, is an important task for settlement and stability analysis of structures founded on stabilized mass. The selection of suitable material model is vital for successful finite element analysis. Nevertheless, among all existing constitutive soil models, none of them can capture all aspects of soil behavior. Therefore, the meaningful and quantifiable predictions of field behaviors are possible only if, undisturbed samples or in-situ tests are used for determination of mechanical properties, and the predictive capacity of selected constitutive model comes from the comparison with field observations In the present research work, utilization of cone penetration test (CPT) data for evaluating the mechanical properties of stabilized dredged sediments for geotechnical design and analysis was presented. A large-scale field test at the Port of Gävle was utilized as a case study, to verify the simulated settlement of preloaded stabilized dredged sediments. The stabilized mass–soil classification behavior type was studied utilizing CPT classification charts. Computation of the primary consolidation settlement due to preloading weight were carried out in PLAXIS 2D geotechnical software and verified against field measurements. A suggestion to protect the stabilized mass against severe weather condition was discussed.