Numerical analysis of piled embankments on soft soils

The construction of embankments on soft soils is a common problem. Soft soil cannot sustain external loads without having large deformations. Piled embankments system provides a possible solution for the construction of roads and railways over soft soils. Until now, the system behaviour could only be described by analytical models such as those included in British or German codes. This paper describes research undertaken to investigate the effects of pile embankment construction in soft soils. Experimental results are used to help investigate arching effect developed due to differential settlement between pile and surrounding soft soil. A numerical parametric study was carried out to examine the impact of various soil parameters on the pile-embankment system behaviour. The outcome of the parametric study implemented using numerical analysis has been investigated and discussed throughout this paper. Based on the numerical analysis carried out in this research, it was found that the earth pressure coefficient normalized by the passive earth pressure Kp plotted on a vertical profile at the midpoint between piles can give a good illustration of arching behaviour. The findings presented in this paper can be considered as guides for numerical analysis and design criteria of soil arching for embankments constructed over piles

Use of large-diameter, cast-in situ concrete pipe piles for embankment over soft clay

Article originally submitted as "Soil improvement using large diameter, cast-in-situ, thin-wall concrete pipe piles"A new method of using large-diameter, cast–in situ concrete pipe (PCC) piles for embankments over soft clay is introduced in this paper. This PCC pile method offers a relatively quick and cost-effective way for soil improvement as compared with other existing soil improvement methods. The principles and construction techniques involved in this method are described. Full-scale model tests were conducted to evaluate the quality and performance of piles and the responses of the surrounding soils. Methods that can be used to check the quality of the pipe piles are elaborated. A case study that illustrates the application of this method in a piled embankment over soft clay is presented.Han-Long Liu, Jian Chu, and An Den

Nanoparticles for Applications in Cellular Imaging

In the following review we discuss several types of nanoparticles (such as TiO2, quantum dots, and gold nanoparticles) and their impact on the ability to image biological components in fixed cells. The review also discusses factors influencing nanoparticle imaging and uptake in live cells in vitro. Due to their unique size-dependent properties nanoparticles offer numerous advantages over traditional dyes and proteins. For example, the photostability, narrow emission peak, and ability to rationally modify both the size and surface chemistry of Quantum Dots allow for simultaneous analyses of multiple targets within the same cell. On the other hand, the surface characteristics of nanometer sized TiO2allow efficient conjugation to nucleic acids which enables their retention in specific subcellular compartments. We discuss cellular uptake mechanisms for the internalization of nanoparticles and studies showing the influence of nanoparticle size and charge and the cell type targeted on nanoparticle uptake. The predominant nanoparticle uptake mechanisms include clathrin-dependent mechanisms, macropinocytosis, and phagocytosis