No abstract

To understand the relationship between microscopic variables and macroscopic engineering properties of kaolinite particles, a molecular dynamics simulation of triaxial shear tests was developed. The calculations were based on a coarse-grained representation of kaolinite particles, considering the action of Derjaguin–Landau–Vervey–Overbeek forces and the granular interactions. The objective of this study was to provide an understanding of the micro- to macro-linkage of mechanical properties through the development of a versatile numerical framework to accurately duplicate the interactions between clay particles and to study the three-dimensional mechanical behaviour of granular matters. To understand the capabilities of the method, several computer simulations of the periodic true triaxial compression and extension tests of both isotropically and one-dimensionally consolidated specimens were carried out.

The soil moisture characteristic (SMC) curve of a soil describes the relationship between the soil suction (tension in the soil pore water) and its water content. The majority of traditional methods used to obtain SMC curves involve gathering individual point measurements of soil water content over a range of applied soil suctions, and then fitting a curve through these points. Each point measurement requires at least a day of testing to gather, leading to a total testing time of weeks to assemble the whole SMC curve. This paper presents a technique to obtain a complete, continuous SMC curve in a total preparation and testing time of 3–5 days. During evaporative drying of the soil specimen under examination, a digital laboratory balance and a high-capacity tensiometer, both connected to a data acquisition system, monitor continuous pore water loss and suction data respectively. The tensiometer is composed of a pressure transducer for suction measurement and an extremely fine porous ceramic that interfaces between the specimen and the transducer. To date, the technique has been successfully applied to resedimented, non-clay soils. Experimental results from the new method are in agreement with results from capillary fall tests. The paper also provides some insight into tensiometer behaviour and features of SMC curves.

The authors discuss some of the challenges encountered in educating the millennial generation of Civil Engineers. This generation, born during the 1990's, may be characterized by their exposure to smart devices and computers connected to the Internet starting from their toddler years. They have developed a natural affinity and curiosity to take advantage of the computers for play and entertainment, reading, studying and especially communicating. Most millennial students are meanwhile proving to be less/or/uninterested in classical math and mechanics, and in group-thinking and groupstudying, and in anything that involves non-virtual media.Alongside with their special skills of naturally interfacing with software that promise instant digital and virtual rewards, there are justified concerns in educating this generation due to their general lack of interest in a physical, conceptual grasping of the real world. Without an interest in observation and exploration outside the virtual world this generation also appears to trust what the virtual world presents to them. These challenges add to the difficulties of the Civil Engineering profession and education that are among the slowest in introducing technology and innovation.

Insufficient information on existing bridge substructures and foundations poses significant challenges for structural condition evaluation and can cause significant uncertainties for the safety and serviceability of bridges. Characterization and condition evaluation of bridges substructure and foundations will not only help to decrease the vulnerability to natural hazards but also provide opportunities for their reuse with considerable benefits. In this paper, the feasibility of leveraging structural identification techniques to characterize bridge substructures and foundations is investigated. A three-span simply supported bridge located in Mossy, West Virginia, USA, is used as a study case. Modal analysis and finite element model updating techniques are used to investigate and estimate the uncertainties and conditions of the substructure. Updated finite element model for this structure provides valuable information for bridge condition assessment and proves how structural identification is a viable tool for the case considered.