Experimental Study

Topic 1: Experimental investigation from sedimentation to consolidation of marine deposits during marine reclamation

Introduction: Hong Kong faces the severe scarcity of construction land. Hong Kong government approved a reclamation project namely Lantau Tomorrow vision to meet the increasing demand for housing. To reduce the expense of filling material and the environmental impact, sometimes the marine clays on the neighboring seabed would be used as filling material. However, the marine clay has high water content, low permeability and high compressibility. Another problem is that there are two stages during a whole reclamation process: sedimentation and consolidation. Traditional research focuses on primary consolidation only.

New equipment: Conventional tests use different devices to study sedimentation and consolidation separately. However, the soil formation is a continuous process. To study the continuous process, a segmented united apparatus for sedimentation and consolidation (SUASC) is invented. Some features are:

  • Transparent
  • Monitoring pore pressure and water content
  • Applying surcharge loading, vacuum loading
  • Prefabricated Vertical Drain (PVD)
To some extent, this equipment can simulate the whole reclamation process in the laboratory.

Objectives

  • To study the sedimentation and consolidation in a continuous way;
  • To propose a unifying model for linking sedimentation and consolidation;
  • To find a fast and effective way for soil improvement in reclamation.





Topic 2: Reduced physical modeling of marine reclamation from pumping to consolidation

Introduction: Ground improvement methods are usually introduced to accelerate the consolidation process of the dredged soil. Prefabricated vertical drains (PVDs) with vacuum preloading and surcharge preloading are commonly used in reclamation projects. Considering the problems existed in PVDs method, like time-consuming, limited vacuum pressure, prefabricated horizontal drains (PHDs) with vacuum preloading is jointly studied to increase the efficiency.

Objectives: We will investigate the combined efficiency of PVDs and PHDs, providing a critical support to the application of this proposed new super-fast consolidation method in practical reclamation projects. The application of multiple layers of PHDs, and its effective treating height will be studied. A new theory for the PHDs and PVDs with vacuum preloading in Hong Kong marine deposit will be proposed based on the large-scale physical model test.






Topic 3: Experimental study on effect of sand filling on flexural behaviour of FRP pile

Introduction: Steel is commonly adopted for the pile-wall in reclamation engineering, but its corrosion poses a great challenge to the service life. By contrast, a new type of corrosion-resistant material, Fiber-reinforced Polymer (FRP), is getting increasing attention as an alternative of steel in marine environment. The FRP material directly eliminates the corrosion, thereby bringing sustainability benefits to marine infrastructures. In addition, in reclamation engineering, sand will be filled into the FRP pile to increase its flexural resistance and stability. Therefore, the flexural behaviour of FRP hollow pile and sand-filled FRP pile should be clearly understood.

Conclusion

  • Sand filling in the FRP pile can increase its ductility but cannot increase its stiffness. The failure mode of the pile is changed.
  • Sand filling in the FRP pile can prevent the buckling of the compression zone, but has no effect on the tension zone.

Further investigation: To study the flexural behaviour of FRP pile filled with Fiber-reinforced Cemented Sand.






Topic 4: Experimental study of clay-FRP pile interface behaviour under complex static and cyclic loadings

Introduction: The interface shear behaviour between pile materials (steel, concrete, and wood) and marine clay is not sufficient known. To design reliable and cost-effective pile foundation, it is essential to understand the mechanical behaviour at the interface of the pile-marine clay. Since the studies show that the application of FRP or composites with other construction materials, such as steel, concrete, etc., can sufficiently improve the engineering properties of pile foundation. So, it is crucial to study the marine clay-FRP interface behaviour in details for better engineering designs and applications.

Objectives

  • To design and develop a new physical model for the study of the clay-FRP interface behaviour under complex static and cyclic loadings;
  • To study the variations of interface pore pressure and soil stresses.